Suchergebnisse

This thesis is focused on inland sand ecosystems, which are among the most threatened grassland types in Central Europe. These landscapes are highly fragmented and are inhabited by many endangered species in spatially isolated habitats. Recently, populations of the rare site-specific plant species decreased, the vegetation density increased and the typically open habitats became more and more ruderalised. As a reason, an enhanced nitrogen deposition and the abandonment of former extensively used grassland were discussed. Consequently, spontaneous succession can appear. To maintain community structure and population dynamics, different nature conservation management methods were introduced; in particular extensive sheep-grazing regimes became a suitable management tool in dry open habitats. The aim of this thesis was to elucidate the impact of crucial abiotic and biotic factors on succession in threatened inland sand ecosystems in a successional gradient. The main study site was the "Ehemaliger August-Euler-Flugplatz von Darmstadt", a nature protection area in the northern Upper Rhine Valley of Germany. The characteristic plant communities of this site are considered highly threatened types in Central Europe according to the EU Habitats directive. The vegetation complex consists in the eastern part of early-successional stages of a pioneer Koelerion glaucae community, while in the western part mid-successional stages of Armerio-Festucetum trachyphyllae vegetation can be found. The substrates are primarily calcareous sands (Koelerion glaucae) with slight acidification of the topsoil (Armerio-Festucetum). The pre-grazing state in this system was characterised by a mowing regime during the military use and afterwards only by very extensive mowing and mulching. Sheep grazing was established in the area in the years 1999/2000. Nutrient increase, e.g. by atmospheric nitrogen deposition or transfer of soil particles, is a major threat for many types of endangered open vegetation. As a model system we used threatened sandy grassland, where a nutrient addition experiment in a five-fold replicated randomised block design was started in the year 2000. We analysed the whole data set for a nine-year period and ran extended approaches in the years 2007 to 2009. We added nitrogen in low dose (n) to simulate an enhanced atmospheric deposition, nitrogen in high dose (N), nitrogen in high dose in combination with different micro- or macronutrients (NP, NPK, NPKM), phosphorus (P), and a carbon source (C) to immobilise plant-available nitrogen to our experimental plots. Additionally, seed limitation was tested by assessing the local seed rain. The data set was analysed by means of detrended correspondence analysis (DCA) and linear mixed models. The DCA revealed two successional pathways: one line typical for threatened sandy grassland, and another one which was accelerated and clearly separated from the typical one. These separations were only detectable after a "lag phase" of about five years. As a general trend phytodiversity diminished on all plots, but the decrease was significantly stronger on plots with high-dose N, which have also shown higher turnover ratios. Site-specific species from pioneer stages (strategy type "stress-tolerators" and "ruderals") and "Red Data" species decreased with nutrient addition. Additionally, we observed an increase in cover of tall plants, geo- and hemicryptophytes, "competitors/stress-tolerators/ruderals" and competitive grasses on plots with high-dose N. The above-ground phytomass production of phanerogams was up to 3-fold higher following N, NP, NPK or NPKM treatment, but it was significantly lower in the case of cryptogams. In contrast, low-dose nitrogen and phosphorus only had no impact on any species except legumes, which were facilitated predominantly by P. The extended approach has shown that most plants were responsive to nutrient addition and grew taller or set more fruits or seeds. In the local seed rain many autochthonous and allochthonous species were found. Anyhow, most abundant species were non-target species and even Calamagrostis epigejos caryopses were found. It could be shown by a field experiment that floristic structure, successional lines, phytodiversity and plant strategies of the studied system changed after a five-year period and a threatened vegetation type was gradually replaced by one with dominant and/or competitive species. These findings emphasise the importance of long-term observations for the study of effects caused by nutrients. I used a long-term field experiment lasting 10 years for further investigations concerning the effects of sheep grazing as a type of moderate disturbance. As "experiments by nature" happened during this time period, we were also able to study severe biotic (rabbit grazing) and abiotic (drought) disturbances, examining the recovery and resilience of the system after these severe disturbances. Within a six-fold replicated randomised split-plot design, 25-m² plots of Armerio-Festucetum trachyphyllae vegetation were studied from 2000-2009 in the northern upper Rhine valley (Germany). We analysed sheep-grazed and non-grazed plots (both with very low rabbit impact until the first half of 2005). In 2005 we established an additional plot type without rabbit and sheep grazing. Severe rabbit impact was studied in detail from 2006 to 2008 concerning flower resources, seed production, endozoochorous seed dispersal and phytomass extraction. Data were analysed by ordination methods and mixed linear models. Moderate disturbance by sheep grazing maintained species diversity in times of low rabbit densities. Severe drought in 2003 resulted in a marked decrease of species numbers, but the system recovered already in 2004. The subsequently analysed "high rabbit impact" resulted in decreases of species numbers, cover of bryophytes, flower quantities and seed content in faeces. Species numbers also declined on plots without rabbit grazing, but for different reasons. Shifts in phenological phases due to rabbit grazing were not observed, but the sum of flowers and number of flowering species decreased. After the decline of the rabbit population, species numbers slightly increased in 2009. Non-grazed plots showed an increase of litter. Despite severe disturbances by rabbits or drought, the community structure was relatively stable, especially in the case of non-ruderalised plots, and showed only slight changes. We developed a conceptual model showing the high potential of recovery and resilience even in the case of severe disturbances. Besides direct grazing effects like the creation of gaps by extensive livestock grazing, previous studies have shown benefits of seed dispersal (endo-, epizoochory), but little was known about post-dispersal processes such as trampling effects. We investigated the role of sheep trampling for the post-dispersal fate of dung-embedded seeds in sheep and rabbit dung and hypothesised a positive impact for the establishment of seedlings as a consequence of cracking the dung pellets. Sheep and rabbit dung was collected from threatened sandy grassland, and its seed potential was tested in a climate room. In a factorial field experiment we assessed the effects of trampling (using sheep-hoof replicas) and dung type on seedling emergence and fruiting success. For both dung types seedling emergence in the field was only 5 or 7 % of the potential without trampling but 18 or 14 % with trampling. Plots with trampled sheep or rabbit dung both showed significantly more seedlings (3.6- or 2.1-fold), more species (2.4- or 1.9-fold) and more fruiting seedlings (3.9- or 2.6-fold) and fruiting species (2.1- or 1.9-fold) compared to non-trampled dung plots. However, not only target species profited from trampling, but also non-target species. This is disadvantageous regarding nature conservation aims, but the proportion of target species was clearly increased by trampling. Sheep play a multifaceted role in dispersal processes: after endozoochoric transport they act as a sort of "gardener" not only for sheep-dispersed seeds, but also for those dispersed by rabbits.

The term Ambient Intelligence (AmI) refers to a vision on the future of the information society where smart, electronic environment are sensitive and responsive to the presence of people and their activities (Context awareness). In an ambient intelligence world, devices work in concert to support people in carrying out their everyday life activities, tasks and rituals in an easy, natural way using information and intelligence that is hidden in the network connecting these devices. This promotes the creation of pervasive environments improving the quality of life of the occupants and enhancing the human experience. AmI stems from the convergence of three key technologies: ubiquitous computing, ubiquitous communication and natural interfaces. Ambient intelligent systems are heterogeneous and require an excellent cooperation between several hardware/software technologies and disciplines, including signal processing, networking and protocols, embedded systems, information management, and distributed algorithms. Since a large amount of fixed and mobile sensors embedded is deployed into the environment, the Wireless Sensor Networks is one of the most relevant enabling technologies for AmI. WSN are complex systems made up of a number of sensor nodes which can be deployed in a target area to sense physical phenomena and communicate with other nodes and base stations. These simple devices typically embed a low power computational unit (microcontrollers, FPGAs etc.), a wireless communication unit, one or more sensors and a some form of energy supply (either batteries or energy scavenger modules). WNS promises of revolutionizing the interactions between the real physical worlds and human beings. Low-cost, low-computational power, low energy consumption and small size are characteristics that must be taken into consideration when designing and dealing with WSNs. To fully exploit the potential of distributed sensing approaches, a set of challengesmust be addressed. Sensor nodes are inherently resource-constrained systems with very low power consumption and small size requirements which enables than to reduce the interference on the physical phenomena sensed and to allow easy and low-cost deployment. They have limited processing speed,storage capacity and communication bandwidth that must be efficiently used to increase the degree of local "understanding" of the observed phenomena. A particular case of sensor nodes are video sensors. This topic holds strong interest for a wide range of contexts such as military, security, robotics and most recently consumer applications. Vision sensors are extremely effective for medium to long-range sensing because vision provides rich information to human operators. However, image sensors generate a huge amount of data, whichmust be heavily processed before it is transmitted due to the scarce bandwidth capability of radio interfaces. In particular, in video-surveillance, it has been shown that source-side compression is mandatory due to limited bandwidth and delay constraints. Moreover, there is an ample opportunity for performing higher-level processing functions, such as object recognition that has the potential to drastically reduce the required bandwidth (e.g. by transmitting compressed images only when something 'interesting' is detected). The energy cost of image processing must however be carefully minimized. Imaging could play and plays an important role in sensing devices for ambient intelligence. Computer vision can for instance be used for recognising persons and objects and recognising behaviour such as illness and rioting. Having a wireless camera as a camera mote opens the way for distributed scene analysis. More eyes see more than one and a camera system that can observe a scene from multiple directions would be able to overcome occlusion problems and could describe objects in their true 3D appearance. In real-time, these approaches are a recently opened field of research. In this thesis we pay attention to the realities of hardware/software technologies and the design needed to realize systems for distributed monitoring, attempting to propose solutions on open issues and filling the gap between AmI scenarios and hardware reality. The physical implementation of an individual wireless node is constrained by three important metrics which are outlined below. Despite that the design of the sensor network and its sensor nodes is strictly application dependent, a number of constraints should almost always be considered. Among them: • Small form factor to reduce nodes intrusiveness. • Low power consumption to reduce battery size and to extend nodes lifetime. • Low cost for a widespread diffusion. These limitations typically result in the adoption of low power, low cost devices such as low powermicrocontrollers with few kilobytes of RAMand tenth of kilobytes of program memory with whomonly simple data processing algorithms can be implemented. However the overall computational power of the WNS can be very large since the network presents a high degree of parallelism that can be exploited through the adoption of ad-hoc techniques. Furthermore through the fusion of information from the dense mesh of sensors even complex phenomena can be monitored. In this dissertation we present our results in building several AmI applications suitable for a WSN implementation. The work can be divided into two main areas:Low Power Video Sensor Node and Video Processing Alghoritm and Multimodal Surveillance . Low Power Video Sensor Nodes and Video Processing Alghoritms In comparison to scalar sensors, such as temperature, pressure, humidity, velocity, and acceleration sensors, vision sensors generate much higher bandwidth data due to the two-dimensional nature of their pixel array. We have tackled all the constraints listed above and have proposed solutions to overcome the current WSNlimits for Video sensor node. We have designed and developed wireless video sensor nodes focusing on the small size and the flexibility of reuse in different applications. The video nodes target a different design point: the portability (on-board power supply, wireless communication), a scanty power budget (500mW),while still providing a prominent level of intelligence, namely sophisticated classification algorithmand high level of reconfigurability. We developed two different video sensor node: The device architecture of the first one is based on a low-cost low-power FPGA+microcontroller system-on-chip. The second one is based on ARM9 processor. Both systems designed within the above mentioned power envelope could operate in a continuous fashion with Li-Polymer battery pack and solar panel. Novel low power low cost video sensor nodes which, in contrast to sensors that just watch the world, are capable of comprehending the perceived information in order to interpret it locally, are presented. Featuring such intelligence, these nodes would be able to cope with such tasks as recognition of unattended bags in airports, persons carrying potentially dangerous objects, etc.,which normally require a human operator. Vision algorithms for object detection, acquisition like human detection with Support Vector Machine (SVM) classification and abandoned/removed object detection are implemented, described and illustrated on real world data. Multimodal surveillance: In several setup the use of wired video cameras may not be possible. For this reason building an energy efficient wireless vision network for monitoring and surveillance is one of the major efforts in the sensor network community. Energy efficiency for wireless smart camera networks is one of the major efforts in distributed monitoring and surveillance community. For this reason, building an energy efficient wireless vision network for monitoring and surveillance is one of the major efforts in the sensor network community. The Pyroelectric Infra-Red (PIR) sensors have been used to extend the lifetime of a solar-powered video sensor node by providing an energy level dependent trigger to the video camera and the wireless module. Such approach has shown to be able to extend node lifetime and possibly result in continuous operation of the node.Being low-cost, passive (thus low-power) and presenting a limited form factor, PIR sensors are well suited for WSN applications. Moreover techniques to have aggressive power management policies are essential for achieving long-termoperating on standalone distributed cameras needed to improve the power consumption. We have used an adaptive controller like Model Predictive Control (MPC) to help the system to improve the performances outperforming naive power management policies.

The main reason for blaming the EU for not watching the regional reforms more often is based on the idea that the EU has a chance to stimulate and positively influence developments in Central Asia and Kazakhstan and to provide a democratic social model. Many analysts think the EU could use economic relations and business ties in the region for the sake of social development and vice versa arguing that social instability affects the EU business relations forcing Kazakhstani government to finally solve problems and execute necessary democratic reforms. For instance, Sebastien Peyrouse sees the following behavior: "In theory, Europe could make use of its business potential to help spread the social model it incarnates. The EU could thus choose to privilege business relations that commit the participants to ensuring certain legal standards in economic activity and to strengthening the rule of law. This could be done, for instance, by giving preference to Central Asian companies that are committed to respecting the rights of local workers, to fighting corruption, promoting fair competition and good corporate governance, and recognizing the importance of contracts. The long-term objective would be to increase the social responsibility of Central Asian companies – something that has indirect repercussions on the societies" (PEYROUSE 2009, P. 11). Nevertheless, he also doubts that it can be easily done because of possible accusations by using "its own doorstep to tax heavens – particularly in Luxembourg - where Central Asian heads of state, their families and the oligarchs close to them deposit money siphoned off from national wealth" (PEYROUSE 2009, P. 11). However, the history of the EU as a welfare union of states is more powerful than the use of accusations. Therefore, European politicians may successfully use economic ties, contacts, and obligations in long-term trade relations to influence the government to provide better social reforms to secure stability, as well as strengthen the power of the EU as an external player in the region. In this case, the economic topic should serve as a basis for the European strategy in the region. "The EU therefore has every reason to implement forms of development assistance which, by helping European companies to establish themselves in the market, will play a key role in reducing Central Asia's social vulnerability and will contribute to the fight against poverty, which is currently the main issue that needs to be addressed by the international community and by regional governments" (PEYROUSE 2009, P. 11). Continuation of this strategy that will enforce Kazakhstani government to provide the society with necessary reforms will gain a positive image for the union both within the region and globally. This also may help the EU, as an external player, to further obtain influence on governmental decision-making processes. It is obvious that social stability is the key to decrease economical risk factors and to improve the investment climate to benefit the whole development of a country or union. In this case, the EU strategy will profit the EU itself. Chances for a successful realization of such a plan are relatively high. Kazakhstan has been conduction fruitful business with EU Member States. According to the statistics, provided by the German Auswaertiges Amt, Germany takes place number eight in the list of Kazakhstan trading partners with a commodity turnover of EUR 5.7 billion in 2008, and it continues to grow (AUSWAERTIGES AMT 2009). "In this area, Kazakhstan does not hide its ambitions; its "Path to Europe" program clearly states its intention to become one of the main communications hubs between Asia and Europe" (PEYROUSE 2009, P. 9), according to Sebastien Peyrouse, who specialized on Central Asian trade and economic relations. The program called "Path to Europe" was signed by the President in August 2008 and supposed to be implemented during 2009-2011. According to evaluations made by the EU and Kazakhstani political analysts, the program will help to intensify and deepen the political collaboration between Kazakhstan and the EU. The introduction of the program has 3 stages and the basis for implementation of the program was prepared carefully. First of all, the president addressed his hopes for future profitable relations with the EU beforehand, in his annual message to the people of Kazakhstan. This message was used by Kazakhstani officials during political meetings to announce the future document. Finally, the document was signed and came into force in August 2008. The program seemed to be very promising. For instance, in March 2008, during the conference in the Netherlands, organized with the help of the Kazakhstan embassy, the ambassador of the Republic of Kazakhstan, Mainura Murzamadiyeva, familiarized more than 70 representatives of political, informational, and business layers of the Netherlands with the President´s message to the people of Kazakhstan, where he had announced the future program. Many of Dutch political scientists stated that the proposals the president made in his message will definitely intensify political cooperation between Kazakhstan and the EU, attract foreign investments, bring new technologies, and help to bring people of different regions close to each other. Analyzing the program "Path to Europe" that is celebrating its first anniversary this August, since it was signed in 2008, the following objectives are performed by the government of the Republic of Kazakhstan: - Cooperation with the EU countries; - Creation of required conditions for technological cooperation; - Energy cooperation development; - Transport cooperation development; - Technical regulation and metrology cooperation; - Trade-economic relation strengthening and broadening; - Small and medium-sized enterprises development; - Living conditions improvement cooperation; - Humanitarian cooperation; - Kazakhstani legal base improvement and European experience application. Kazakhstan clearly stated that it expects the level of a strategic partnership with leading European countries in political, economic, and humanitarian spheres and a trade commodity turnover increase by 10% per year as well as a high level of exchange visits. The country also expects the EU to help to promote Kazakhstan internationally which will improve the investment climate and, therefore, the economic situation. However, priorities of the country remain unclear showing the country's reluctance to answer the questions on how to establish democracy and solve the following problems "continuation of efforts on creation of conditions for democracy institutions development on the OSCE territory; transport and transit potential development; Eurasian transcontinental transport corridors development; ecological problems solutions; trust measures and regional security strengthening; non-military aspects of safety development under the OSCE activities including terror, extremism, drug trafficking, organized crime, weapons' and people's sale fighting and Afghanistan reconstruction". To reach the declared goals and priorities, Kazakhstan needs the support of the EU and cooperation. Many political and business analysts provide recommendations suggesting to establish trade chambers and delegation sections related to trade and business that will monitor the activities, provide more legal support and consultations for small and medium-sized business in the region. Further, they suggest establishing more exchange programs for Kazakhstani businessmen to bring more business culture and experience. To monitor and evaluate the progress, the EU can establish clear and visible rating systems with distinct conditions and deadlines. In this case, evaluation committees and reports with full transparency are crucial. However, the first step, the EU should fulfill, is to admit that the time of 'soft power' has ended and finally declare a clear political dimension. Without a distinctive view and goal, the EU will not succeed in representing a strong power and will not improve the policy that has been executing in Kazakhstan since signing the Partnership and Cooperation Agreement in 1992.

Munuaisten vajaatoiminta on diabeteksen ja sydän- ja verisuonisairauksien yleistymisen takia maailmassa voimakkaasti lisääntymässä oleva sairaus. Munuaisten tehtävä elimistössä on aineenvaihdunnan tuotteiden poisto ja vesitasapainon säätely, jolloin munuaisen glomeruluksissa eli munuaiskeräsissä verenkierrosta suodattuu virtsatiehyeisiin virtsaa. Munuaiset säätelevät myös kalsiumin, fosfaatin ja D-vitamiinin aineenvaihduntaa ja vaikuttavat punasolutuotantoon tuottamalla erytropoietiinia. Munuaisten vajaatoiminnassa glomerulusfiltraatio (GFR) heikentyy. Tällöin kertyviä haitallisia aineenvaihduntatuotteita voidaan poistaa keinomunuais- eli dialyysihoidolla. Munuaisten vajaatoiminnassa immuunipuolustus on heikentynyt, ja riski infektioille lisääntynyt. Infektiot ovat toiseksi yleisin kuolinsyy dialyysipotilailla sydän- ja verisuonisairauksien jälkeen. Immuniteettiä heikentävät puolustuskykyä tukevien tulehdusvälittäjäaineiden puute, toksiset aineenvaihduntatuotteet, ja verikontakti vieraiden materiaalien kanssa hemodialyysihoidossa. Fosfaatin kertymiseen liittyvä sekundaarinen lisäkilpirauhasen liikatoiminta eli hyperparatyreoosi on immuunisoluille toksista. Kalsitriolin eli aktiivisen D-vitamiinin puute voimistaa hyperparatyreoosia. Terveillä kalsitrioli hillitsee immuunivastetta, ja D-vitamiinipuutokseen liittyy lisääntynyt riski mm. autoimmuunitauteihin ja pahanlaatuisiin sairauksiin. Vaurioitunut munuainen ei kykene muuntamaan kalsitriolin esiastetta kalsitrioliksi, josta seuraa D-vitamiinipuutos. Se ei myöskään kykene tuottamaan riittävästi erytropoietiinia (Epoa), joka johtaa anemiaan. Tässä väitöskirjatyössä tutkittiin soluvälitteistä immuniteettiä ja rokotevastetta munuaisten eriasteista vajaatoimintaa sairastavilla potilailla sekä koe-eläimillä. Influenssarokotevastetta verrattiin normaalin munuaistoiminnan omaavien sydänpotilaiden vasteisiin. Lisäksi tutkittiin potilaiden ja kontrollien seeruminäytteistä, sekä influenssan sairastaneiden varusmiesten näytteistä, säilyykö vaste seuraavien vuosien epidemioista eristettyjä virusantigeenejä kohtaan. Selvitettiin fosfaatinsitojana käytetyn ravinnon kalsiumkarbonaattilisän vaikutusta tetanusrokotevasteeseen rotilla, joille oli tehty munuaisten osapoistoleikkaus. Tutkittiin myös kalsitriolin ja Epo-hoidon aloituksen vaikutuksia soluvälitteiseen immuniteettiin. Munuaisten vajaatoimintaa sairastavien potilaiden influenssarokotevaste oli lähes kontrollien luokkaa, eikä hemodialyysipotilaiden vasta-ainevaste epidemiaviruksia kohtaan ollut kontrolleja huonompi. Suonensisäinen kalsitriolihoito kohensi influenssarokotevastetta hemodialyysipotilailla (lähes merkitsevästi, p=0.06). Rotilla, joilla oli munuaisten vajaatoiminta, todettiin selvästi heikentynyt tetanusrokotevaste, joka korreloi glomerulusfiltraatioon sekä fosfaatti- ja lisäkilpirauhashormonitasoon. Ravinnon kalsiumkarbonaattilisä kohensi tetanusrokotevastetta rotilla. Soluviljelmille annosteltu kalsitrioli hemodialyysipotilailla heikensi lymfosyyttistimulaatiovastetta mutta pulssittain annettuna pikemminkin kohensi sitä (tilastollisesti ei-merkitsevästi). Epo heikensi lymfosyyttiproliferaatiota ja vähensi lymfosyyttien ja niiden alaluokkien määrää. Johtopäätökset: Munuaisten vajaatoiminnassa influenssarokotevaste on kontrollien kaltainen. Vain hemodialyysipotilailla se on osittain heikentynyt. Korkea-annoksinen kalsitrioli koeolosuhteissa ja Epo-hoidon aloitus vaimentavat soluvälitteistä immuniteettiä. Kalsitriolilla ja fosfaatinsitojana käytetyllä kalsiumkarbonaatilla on suotuisa vaikutus rokotevasteeseen. ; Background. Chronic kidney disease (CKD) is a globally increasing condition that almost always finally leads to renal replacement therapy (dialysis treatment). CKD is also a state of immunodeficiency with increased susceptibility to infections that are the second most common cause of death after vascular diseases among dialysis patients (Rocco et al. 2002; Collins et al. 2006; Inaguma et al. 2008). In an earlier Finnish doctoral study in 1985, lymphocyte antigen responses of hemodialysis (HD) patients were only 60% of the controls (Huttunen 1985). The vaccination response is also impaired e.g. against influenza (Beyer et al. 1987; Cavdar et al. 2003). Uremic toxins, lack of supportive cytokines, constructive cellular factors, dialysis modality and the membranes used in HD are all involved in the immune suppression. An important cause of dysfunction in the cells of the immune system is intracellular hypercalcemia related to secondary hyperparathyroidism (SHPT) caused by retention of phosphate in CKD. Patients with advanced CKD also by nature develop hypovitaminosis D, because the kidneys have lost their ability to synthesize calcitriol, which is known to have immunoregulatory actions. This contributes to SHPT and the numerous immune abnormalities. Initiation of erythropoietin (Epo) treatment has also been shown to affect the immune functions. By and large, the effects of the treatments of CKD on immune functions remain to be clarified. Aims. In this series of studies we aimed to study the influenza vaccination response against vaccine antigens in CKD of various degrees (I) and HD-patients cross-reacting antibody responses to wild influenza virus antigens (II). We also aimed to study whether phosphate binding with calcium carbonate could increase the reduced tetanus vaccination response in uremic rats (IV). We aimed to study the immune effects of ancillary treatments in CKD, calcitriol (III) and Epo (V), on lymphocyte functions. Subjects and methods. The groups in the clinical studies consisted of patients with all stages of CKD and controls from Tampere University Hospital. Pre-dialysis (Pre-D), HD, peritoneal dialysis (PD) and cardiac control patients were vaccinated against influenza and their antibody response against the influenza vaccine antigens A/H3N2, A/H1N1 and B was measured. HD patients sera were additionally studied for cross-reactivity against subsequent years virus isolates of A/H3N2 subtype. In vitro calcitriol was added in lymphocyte cultures of HD patients in a lymphocyte antigen response study using tuberculin (PPD) and tetanus toxoid (TT) as antigens. In the experimental study rats underwent a 5/6-nephrectomy or a sham operation, and thereafter they were given a high or control calcium carbonate diet, and their tetanus vaccination response was evaluated. Pre-D patients were tested with 1) antibody tests to Ebstein-Barr virus (EBV) and cytomegalovirus (CMV), 2) lymphocyte subclass analyses and 3) lymphocyte proliferation tests using phytohemagglutinin (PHA), pokeweed mitogen (PWM), PPD and TT as stimulants, before and three months after they begun with Epo treatment. Results. Influenza vaccination of CKD patients resulted in post-vaccination titres that were almost comparable to those of the controls. Against A/H3N2 antigen they were 84%, 84% and 96% of the controls titres (pre-D, HD and PD, respectively). Sixty-one percent of controls and 67% of PD patients reached a protective titre against A/H3N2 but no more than 35% of pre-D and 36% of HD patients. However, the proportion of CKD and control patients that reached protective titres was clearly higher for the two other antigens A/H1N1 and B. Among HD patients, those on intravenous (i.v.) calcitriol seemed to have a better protection than those without i.v. calcitriol (p=0.06, borderline significant). The antibodies efficiently cross-reacted against wild influenza virus A/H3N2 antigens, similarly in HD patients and controls and even in healthy military conscripts who had suffered from an influenza A infection previously. In the lymphocyte proliferation studies, the effect of in vitro pulse (mimicking i.v.) calcitriol therapy among HD patients had a statistically non-significant enhancing effect on lymphocyte antigen stimulation cultures, whereas having calcitriol continuously in the culture medium was even immunosuppressive to TT (p=0.001). High calcium diet was beneficial to the tetanus vaccination response of rats with 5/6-nephrectomy: the response of the Ca-NTX rats with high calcium diet was almost as high as (75% of) that of sham-operated (Sham) rats (p=NS), while the NTX rats with control calcium diet had a reduced response (42%) compared to the Sham rats, p The initiation of Epo treatment in pre-D patients caused lymphopenia and a decrease in lymphocyte proliferation, but no changes in the general antibody production against EBV and CMV. The changes in iron status, reticulocytes, hemoglobin or glomerular filtration rate (GFR) did not explain the decline. Conclusions. The influenza vaccination responses of regularly monitored patients with CKD were comparable to controls. Especially HD patients cross-reactivity against several wild viruses was not inferior to that of the controls. In 5/6-NTX animals, the impaired tetanus vaccination response correlated both to GFR and to the control of hyperphosphatemia and PTH level. Calcitriol in vivo borderline significantly (p=0.06) enhanced the influenza vaccine response and calcitriol in vitro pulse treament slightly (non-significantly) enhanced lymphocyte antigen proliferation of HD patients. Incubation with calcitriol in vitro continuously was immunosuppressive to TT response (p=0.001). Epo had initial immune depressing actions to lymphocyte number and function. There seemed to be clinical benefits of calcitriol and phosphate binding therapies in vaccination response in CKD.

1. May 1983. Rino Valdameri, director of the Accademia di Belle Arti di Brera (the Brera Academy of Fine Arts), and Senator Alessandro Poss, propose to the authorities of the city of Rome a monument in honour of the most celebrated poet of Italians. This project is entrusted to architects Pietro Lingeri and Giuseppe Terragni, and is given the name Danteum. In October 1938, architects and promoters were called on Thursday 10th November, at 5.30pm, at Palazzo Ducale di Venezia (Doge¿s Palace) in order to present their project to Benito Mussolini. In May 1939, a second audience with the Duce had to be cancelled and the possible execution of the project was threatened. On 1st September 1939 Germany invades Poland. Due to constant requests for a second audience, promoters receive the answer of the Segretario particolare di S.E. il Capo del Governo, who announces that better times for the audience are to come. A day later, Terragni is mobilized and assigned to the third regiment of artillery of the army at Cremona. Nevertheless, the project suffered several modifications until spring 1941. By the end of January 1943, Terragni was repatriated and taken to the military hospital in Cesenatico. On 19th July Terragni died suddenly a few meters away from his house. On 25th July, king Victor Emmanuel III of Italy gives the order to arrest Mussolini. During the bombing of the allied troops in 1944, Lingeri saves the original documents of the Danteum project: a series of drawings with mixed technique, watercolour and ink on Fabriano white paper, assembled on rigid panels made to scale 1:100, and a wooden model, scale 1:50. On 28th April 1945, Mussolini was seized and executed by the partisans. In September 1957, the Danteum was published by the first time in a magazine. 2. The project¿s central argument fixes a composite correspondence with Commedia (The Divine Comedy), from the common structures ¿proportions and measures- that the architecture work may take from Dante¿s poem. Such dependence between architecture and literature has consigned the Danteum, from time to time, further than the architecture field, provoking its exile from the inscrutable architectonic specificity, condemned by its involvement against the autonomy of the discipline, and for such a personal and excessive gesture. 3. Why a hybrid object, not very convenient, instead of the major works of its author? The fissure that emanates from the Danteum does not refer to architecture as a stationary, closed and finite product, but to a transition between the univocally formal and the narrative vertigo. Within this process, which unites and separates the arbitrary issues from the strictly disciplinary, is the will of our choice. With its liminal logic, the Danteum spreads like a shadow in times of modern brightness. A kind of non-architecture as an existential point, which may be said to be ¿not totally¿ and which exception makes everything exist. In this landscape of non-arranged notions, the coexistence of architectonic and non-architectonic terms gives rise to paradoxes and antonyms very propitious for the analysis of uncertainties spread under the paradigmatic dominance of modern architecture. 4. The most relevant is not the search of the author, but the process of this search. Lingeri and Terragni are only suspicious and respond only to research interests. The research process has not followed a straight line in the attempt to examine the Danteum project anatomy, which has needed a dramatic and quasi mythological element in order to disguise its modern face. The result is a mosaic of half defined and half blurred, with reflexes, drafts, notes. In this context, history occurs like the movement of a scalpel in the dissection of a corpse. ; 1. Mayo de 1938. Rino Valdameri, presidente de la Academia de Brera, y el senador Alessandro Poss, proponen a las autoridades en Roma un monumento en homenaje al máximo poeta de los italianos. El encargo es encomendado a los arquitectos Pietro Lingeri y Giuseppe Terragni, el nombre del proyecto: el Danteum. En Octubre de 1938, los arquitectos y los promotores son convocados para el jueves 10 de Noviembre, hora 17:30, al Palacio Venecia para presentar el proyecto a Benito Mussolini, Capo de Governo. El proyecto es bien recibido, aprobándose su continuación. En mayo de 1939, es suspendida una segunda audiencia con el Duce, la posible realización del proyecto se ve amenazada. El 1 de septiembre de 1939 Alemania invade Polonia. A los continuos pedidos de esta segunda audiencia, el 4 de septiembre de este mismo año, los promotores reciben la respuesta del Segretario particolare di S.E. il Capo del Governo, anunciando que el actual momento no es el más oportuno. Un día después Terragni es movilizado y asignado al III regimiento de artillería de cuerpo de armada en Cremona; aún así se realizarán algunas modificaciones al proyecto hasta la primavera de 1941. A finales de enero de 1943, Terragni es repatriado e internado en el hospital militar de Cesenático. El 19 de julio, inesperadamente, Terragni muere a pocos metros de su casa. El 25 de julio, el rey Victor Manuel III hace apresar a Mussolini. Durante el bombardeo aliado de 1944, Lingeri salva los originales del proyecto del Danteum de ser destruidos: una serie de dibujos con técnica mixta, acuarela y tinta sobre papel blanco de Fabriano, montados sobre paneles rígidos a escala 1:100, y una maqueta realizada en madera, escala 1:50. El 28 de abril de 1945 Mussolini es capturado y fusilado por los partisanos. En septiembre de 1957, el Danteum es publicado por primera vez en una revista. 2. El argumento central del proyecto establece una correspondencia compositiva con la Divina Commedia, desde las estructuras comunes -proporciones y medidas- que la obra de arquitectura puede sustraer del poema de Dante. Tal dependencia entre arquitectura y literatura ha relegado al Danteum, de tanto en tanto, más allá del confín del territorio arquitectónico, provocando su destierro del centro hermético de la especificidad arquitectónica, condenado por sus implicaciones contra la autonomía de la disciplina, y por esa gesticulación tan suya y excesiva de histrión. 3. ¿Por qué un objeto híbrido, de género incómodo, y no las obras mayores de su autor? El intersticio que se crea con el Danteum no alude a la arquitectura como un producto estacionario, cerrado y finito, sino como una transición entre lo unívocamente formal y el vértigo narrativo. En esta liminidad, que une y separa lo arbitrario de lo estrictamente disciplinar, está la voluntad de nuestra elección. Con su lógica fronteriza el Danteum se despliega como una sombra en tiempos de claridad moderna. Una especie de no-arquitectura como punto existencial del que puede decirse que no es "del todo" y que además hace existir el todo por su excepción. En este paisaje de nociones no concertadas, la coexistencia de términos arquitectónicos y no arquitectónicos da lugar a paradojas y antinomias muy propicias para el análisis de las incertidumbres sembradas en el dominio paradigmático de la arquitectura moderna. 4. Lo importante no es la búsqueda del autor, sino la procesualidad de esa búsqueda, de ese acto. Lingeri y Terragni quedan como meros sospechosos, y a veces respondiendo sólo a intereses narrativos. No hay ninguna dirección lineal en el intento de examinar la anatomía de este acontecimiento fenomenal que ha precisado un elemento dramático y cuasi mitológico para encubrir su vestidura moderna. Lo que queda es un mosaico de figuras medio definidas medio borrosas, de reflejos, de apuntes, de notas. En este apenas, la historia tiene lugar como el movimiento de un bísturi en la disección de un cadáver. ; Postprint (published version)

Inhaltsangabe: Einleitung: Ein Ereignis zu benennen, welches in den Jahren 2007 und 2008 beinahe die gesamte Aufmerksamkeit aller weltweiten Akteure aus Politik, Wirtschaft, Wissenschaft, Medien und Bevölkerung in Anspruch nahm, fällt nicht schwer. Es handelt sich um die amerikanische Immobilienkrise und ihre Folgeerscheinungen. Selten zuvor wurde eine einzelne Angelegenheit zum Objekt der gesamten öffentlichen Aufmerksamkeit. Diese Nachrichtenaktualität zeigt, dass die Krise jeden betrifft, auch wenn sie originär in den USA ihren Ursprung hatte. Durch Finanzmanipulationen konnten sich die Auswirkungen weltweit verbreiten und sind daher auch weltweit spürbar. Selbst kleine Gemeinden in Deutschland berichten aufgrund von Investitionen in amerikanische Immobilienfonds von Wertberichtigungen in ihren Haushaltsbilanzen. Gerade weil die Krise allgegenwärtig scheint, haben viele Menschen weltweit ein Interesse an Hintergrundinformationen über dieses Ereignis. Dafür ist für viele Menschen der Zusammenhang zwischen Immobilienkrise und den nun spürbaren Ereignissen auf dem Finanzmarkt und der Weltwirtschaft nicht offensichtlich. Das erste Ziel dieser Arbeit ist es daher aufzuzeigen, wie sich ein nationaler Immobilienboom in eine nationale Immobilienkrise verwandelt konnte, um dann in Form einer globalen Finanzkrise den gesamten Globus zu erschüttern. Im globalen Finanzsystem, welches bisher von der Krise am stärksten erschüttert wurde, spielt die Stadt New York eine wichtige Rolle. Denkt man an New York City, so hat man automatisch die Hochhäuser der Banken, die Wall Street und den Aktienhandel vor Augen. Doch spätestens durch den Zusammenbruch der Aktienkurse im Jahr 2001 ist der weltweite Einfluss des Finanzplatzes New York City auch in negativer Weise bekannt. Schon damals zweifelte man daran, dass sich die Stadt New York vom Aktiencrash und den anschließenden Terroranschlägen des 11. September 2001 wieder erholen würde. Allen Kritikern zum Trotze, gelang es jedoch der Stadt stärker als jemals zuvor aus der Krise hervorzugehen. So schreibt John Strausbaugh von der New York Times über die Stadt New York: 'Geographically and historically, New York City begins in the small space below Wall Street. And when disaster strikes the area, as it has often done, it can seem as if the city will end there too. But if the nearly four centuries of history there tell anything, it's a story of survival. As it grew from the tiny Dutch outpost of New Amsterdam to today's forest of skyscrapers, Lower Manhattan outlived military occupation, enormous fires, terrorist massacres and a long string of stock-market crises'. Durch die Immobilien- und Finanzkrise ist New York City nun erneut in Gefahr. Mit der Krise kamen wieder viele Fragezeichen auf, inwieweit und ob überhaupt sich New York nach diesem neuerlichen Schicksalsschlag wieder erholen kann, oder ob nach dieser Krise Strausbaughs 'Story of Survival' für New York endgültig zu Ende gehen wird. Auch dieser Aspekt wird in der vorliegenden Arbeit konsequenterweise beleuchtet. Gang der Untersuchung: Im Grundsatz ist die Arbeit so aufgebaut, dass sie von der Breite des Themas auf den Punkt der Aufgabenstellung hinführt. Bereits der Titel lässt erkennen, dass sich die Arbeit mit drei grundsätzlichen Aspekten beschäftigt: Der erste Aspekt handelt von der Immobilienkrise und deren Ausdehnung zur Finanzkrise. Der zweite Gesichtspunkt beschreibt hingegen die Entstehung und die Vorherrschaft des Wirtschaftsstandortes New York City mit der Wall Street als globalem Finanzzentrum. Im dritten Aspekt werden nun die ersten beiden Punkte zusammengeführt und es wird die Korrelation der Variabeln Immobilien- und Finanzkrise auf der einen Seite und dem Weltfinanzzentrum New York City auf der anderen Seite analysiert. Dieser Punkt betrachtet die Folgen der Krise für den Wirtschaftsstandort New York und ist damit, wie der Titel schon verrät, der Hauptbestandteil der Arbeit. Der Aufbau ist zudem so strukturiert, dass er anhand zweier Entwicklungslinien aufgezeigt werden kann. Zum einen gibt es den Aufbau nach geographischem Gesichtspunkt in Form einer umgekehrten Pyramide (Abbildung 1.1). Dazu wird konsequenterweise das Spektrum von der amerikanischen Immobilienkrise auf die Folgen für eine einzige amerikanische Metropole, nämlich den Wirtschaftsstandort New York, verengt. Zusätzlich beinhaltet diese Vorgehensweise auch einen chronologischen Ablauf. Dem Ausbruch der Immobilienkrise in den Jahren 2006 und 2007, folgt der Ausbruch einer Finanzkrise im Jahr 2008. Im Rahmen der Arbeit werden zusätzlich im Kapitel 4 zum einen kurz- und mittelfristige Entwicklungen für die Jahre 2009 bis 2012, sowohl im Kapitel 5 langfristige Szenarien bis 2020 aufgezeigt. Daraus ergibt sich der folgende Aufbau: Nachdem im ersten Kapitel das Ziel und der Aufbau der Diplomarbeit aufgezeigt werden, richtet sich das Augenmerk im zweiten Kapitel auf die Entstehung und die Ursachen der amerikanischen Immobilienkrise. Als wichtigen Hintergrund wird zusätzlich die Ausdehnung zur Finanzkrise erläutert. Dabei spielen die Methoden der Geldbeschaffung und somit der Gestaltung von Subprime-Krediten eine wichtige Rolle. Im dritten Kapitel wird auf die Bedeutung der Wall Street für New York City und damit auf den Finanzsektor als Motor für die New Yorker Wirtschaft eingegangen. Mit dem Aufstieg der Wall Street hat sich auch New York City zum globalen Finanzzentrum herausbilden können. Diese Entwicklung rechtfertigt erst den Blick auf den Zusammenhang zwischen Immobilien- und Finanzkrise und der Finanzmetropole New York. Den Kern der Arbeit bildet das Kapitel vier, welches die Auswirkungen der Immobilien- und Finanzkrise auf den Wirtschaftsstandort New York City beschreibt. Durch den Totalzusammenbruch der Investmentbranche, zeigen sich unmittelbar negative Einflüsse, deren Talsohle erst 2010 durchschritten sein wird. Der Blick in die Jahre 2016 bis 2020 wird im Kapitel fünf beschrieben. In diesem Kapitel wurden drei Szenarien erarbeitet, die jeweils das zukünftige Wirtschaftsleben in New York aufzeigen. Eines dieser Szenarien wird am Ende als wahrscheinlich hervorgehoben.Inhaltsverzeichnis:Inhaltsverzeichnis: 1.Einleitung1 1.1Ziel der Arbeit1 1.2Aufbau der Arbeit2 2.Die amerikanische Immobilienkrise und deren Ausdehnung zu einer weltweiten Finanzkrise5 2.1Die Voraussetzungen für die Immobilienkrise5 2.1.1Die Zinspolitik der amerikanischen Zentralbank als Basis für einen Immobilienboom 5 2.1.2Subprime-Kredite führen zur Entstehung einer Hypothekenblase7 2.1.3Fallende Immobilienpreise11 2.2Wie aus der Immobilienkrise eine Finanzkrise werden konnte14 2.2.1Definitionen und modelltheoretische Überlegungen14 2.2.2Die Verbriefung von Hypothekenkrediten und der Handel an der Wall Street18 2.2.3Die Krise nimmt ihren Lauf25 2.2.4Ausdehnung zur weltweiten Finanzkrise31 3.Die Bedeutung der Wall Street für New York City37 3.1New Yorks Aufstieg zur Wirtschaftsmetropole37 3.2Der Finanzsektor als Motor für die New Yorker Wirtschaft41 3.2.1Die Wall Street als Finanzsektor: Begriffserklärung und Definition41 3.2.2Die Anfänge der Wall Street als Finanz- und Handelsplatz43 3.2.3Der Aufstieg zum Weltfinanzzentrum46 3.3Die Indikatoren der Weltfinanzhauptstadt New York50 3.3.1Die New Yorker Aktienbörsen51 3.3.2Angesiedelte Unternehmen und das New Yorker Gross City Product54 3.3.3Löhne und Beschäftigung in New York City57 3.3.4Central Business Districts, Bürofläche und Mieten in Manhattan59 4.Die Auswirkungen der Immobilien- und Finanzkrise auf den Wirtschaftsstandort New York62 4.1Negativeinflüsse der Finanzkrise63 4.1.1Kursverfall und andere Abwertungen an der Wall Street63 4.1.2Das Ende der Investmentbanken und der Absturz der New Yorker Firmen im Finanzsektor67 4.1.3Massenentlassungen an der Wall Street77 4.1.4Wall Street Bonuszahlungen und Konsum82 4.1.5Auswirkungen auf den Immobilienmarkt in New York City84 4.1.6Steuerausfälle für den New Yorker Haushalt91 4.2Die mittelfristige Wirtschaftsentwicklung von New York City95 4.2.1Der CEI-Index der New Yorker Notenbank95 4.2.2Der modifizierte CEI-Index und die aktuellen Wirtschaftsdaten96 4.2.3Mittelfristiger Ausblick der New Yorker Wirtschaftsentwicklung98 5.Wie ein globales Ungleichgewicht die langfristige Zukunft New Yorks beeinflusst100 5.1Die Rolle der globalen Ungleichgewichte100 5.2Die drei Zukunftsszenarien104 5.2.1Das globale 'Snail Szenario'105 5.2.2Das amerikanische 'Bear-Szenario'107 5.2.3Das New Yorker 'Bull-Szenario'109 5.3Vergleich der Szenarios111 6.Schlussbetrachtung112 Literaturverzeichnis114 Anhang135 Danksagung143Textprobe:Textprobe: Kapitel 4.1.2, Das Ende der Investmentbanken und der Absturz der New Yorker Firmen im Finanzsektor: 'The fiscal challenges facing New York City in the coming years have deepened with every month that the paralysis facing the nation's credit markets continues. Waves of negative economic developments during the City's 2008 fiscal year — including the near-collapse of Bear Steams — swelled into a tsunami in September 2008 as spasms of financial anxiety brought down Lehman Brothers, forced AIG into a federal bailout, caused Merrill Lynch to merge with Bank of America, and led Goldman Sachs and Morgan Stanley to reorganize as bank holding companies.', William C. Thompson, 2008. Wie im Kapitel 3.3 aufgezeigt wurde, befanden sich vor dem Eintritt der Krise die Zentralen der fünf größten Investmentbanken der Welt in New York City. Dabei sind reine lnvestmentbanken eine angelsächsische Spezialität. Sie nehmen in der Regel keine Einlagen der Privatkundschaft entgegen und vergeben weniger Kredite an Unternehmen, sondern konzentrieren sich auf das Wertpapiergeschäft. Durch die Finanzkrise waren im Frühherbst 2008 jedoch nur noch zwei Investmentbanken übrig geblieben. Dabei sagte der frühere Notenbankchef Alan Greenspan im Jahr 2006 noch: 'Not only have individual financial institutions become less vulnerable to shocks from underlying risk factors, but also the financial system as a whole has become more resilient' (zitiert bei Goodman 2008). Damit sollte er jedoch Unrecht behalten. Im Folgenden werden die Entwicklungen der großen New Yorker Banken während der Krise im Einzelnen beschrieben. Bear Stearns: Die kleinste der New Yorker lnvestmentbanken war Bear Stearns. Sie wurde bereits am 17. März 2008 von J.P. Morgan Chase für nur zwei Dollar pro Aktie mit einem Kredit der Notenbank übernommen. Während des vorangegangenen Wochenendes, hatte Bear Stearns 93 Prozent seines Unternehmenswertes an der Börse eingebüßt. Anfang 2007 war die Aktie noch 171 Dollar wert gewesen. Im Laufe des Jahres 2008 kam dann Bear Stearns gleich dreimal in Schwierigkeiten. Bereits am 13. März 2008 waren mit 18 Milliarden Dollar die Kreditreserven der Bank plötzlich vollständig aufgebraucht. Ein Konkursantrag war damals schon in Vorbereitung. Doch in letzter Minute eilte die Großbank J.P. Morgan Chase zu Hilfe. Diese Rettung war aber nur durch Unterstützung der Notenbank möglich, die 29 Milliarden an Einlagen der insolventen Bank garantierte. Diese Intervention wurde damals als Wendepunkt der Finanzkrise angesehen. Allerdings sollte sich in der Woche vom 8. bis zum 14. September 2008 (Anhang 3) die Finanzkrise und damit die wirtschaftliche Lage in New York weiter zuspitzen. Lehman Brothers Nachdem der Vorstandsvorsitzende der New Yorker lnvestmentbank Lehman Brothers (Lehman) am 11 September die Quartalszahlen des Unternehmens und die daraus resultierenden Abschreibungsbeträge verkündete, stürzte der Aktienkurs noch am selben Tag um 46 Prozent ab. Dadurch waren im Verlauf der Krise die Gesamtverluste auf 90 Prozent des Unternehmenswertes bzw. 40 Milliarden Dollar angestiegen. Zusätzlich hatte Lehman rund 600 Milliarden Schulden in den Büchern zu verzeichnen. Das Unternehmen war schlichtweg zahlungsunfähig. Der Aktienkurs stürzte von 47,52 Dollar auf 0,03 Dollar ab. Zwar meldete die britische Bank Barclays zunächst Kaufinteresse an Lehman an, die amerikanische Notenbank verweigerte jedoch überraschend die von den Briten geforderte Beteiligung oder Garantie. Daher meldete Lehman Brothers am 15. September 2008 die Insolvenz an. Dieses Ereignis bedeutete das Ende einer der ältesten und traditionsreichsten Investmentbanken an der Wall Street. Lehmans Wurzeln gehen zurück auf 1850. Während der 158 Jahren dazwischen hatten sich bei der Bank ungefähr 25.000 Arbeitnehmer angesammelt (Anderson, White 2008: Al). Das Problem, das letztendlich zum Konkurs von Lehman führte, war bei allen lnvestmentbanken ähnlich. Die Kapitalausstattung im Verhältnis zu den Risiken, die sie vor allem durch das lnvestment in Wertpapiere aus ABS oder CDS stark erhöhten, war viel zu gering. Beinahe das gesamte Vermögen wurde in Form zweifelhafter Wertpapiere gehalten, für die es zu diesem Zeitpunkt schon über ein Jahr lang keine liquiden Mittel mehr gab. Diese Papiere waren wertlos geworden und mussten verlustbringend abgeschrieben werden. Als darin Anfang September die Rating-Agenturen ankündigten, dass die Kreditwürdigkeit des Unternehmens herabgestuft werden sollte, wurde die Verkaufspanik weiter verstärkt. Die ohnehin schon unsicheren Investoren zogen die letzten liquiden Einlagen aus der Bank.

1. May 1983. Rino Valdameri, director of the Accademia di Belle Arti di Brera (the Brera Academy of Fine Arts), and Senator Alessandro Poss, propose to the authorities of the city of Rome a monument in honour of the most celebrated poet of Italians. This project is entrusted to architects Pietro Lingeri and Giuseppe Terragni, and is given the name Danteum. In October 1938, architects and promoters were called on Thursday 10th November, at 5.30pm, at Palazzo Ducale di Venezia (Doge¿s Palace) in order to present their project to Benito Mussolini. In May 1939, a second audience with the Duce had to be cancelled and the possible execution of the project was threatened. On 1st September 1939 Germany invades Poland. Due to constant requests for a second audience, promoters receive the answer of the Segretario particolare di S.E. il Capo del Governo, who announces that better times for the audience are to come. A day later, Terragni is mobilized and assigned to the third regiment of artillery of the army at Cremona. Nevertheless, the project suffered several modifications until spring 1941. By the end of January 1943, Terragni was repatriated and taken to the military hospital in Cesenatico. On 19th July Terragni died suddenly a few meters away from his house. On 25th July, king Victor Emmanuel III of Italy gives the order to arrest Mussolini. During the bombing of the allied troops in 1944, Lingeri saves the original documents of the Danteum project: a series of drawings with mixed technique, watercolour and ink on Fabriano white paper, assembled on rigid panels made to scale 1:100, and a wooden model, scale 1:50. On 28th April 1945, Mussolini was seized and executed by the partisans. In September 1957, the Danteum was published by the first time in a magazine. 2. The project¿s central argument fixes a composite correspondence with Commedia (The Divine Comedy), from the common structures ¿proportions and measures- that the architecture work may take from Dante¿s poem. Such dependence between architecture and literature has consigned the Danteum, from time to time, further than the architecture field, provoking its exile from the inscrutable architectonic specificity, condemned by its involvement against the autonomy of the discipline, and for such a personal and excessive gesture. 3. Why a hybrid object, not very convenient, instead of the major works of its author? The fissure that emanates from the Danteum does not refer to architecture as a stationary, closed and finite product, but to a transition between the univocally formal and the narrative vertigo. Within this process, which unites and separates the arbitrary issues from the strictly disciplinary, is the will of our choice. With its liminal logic, the Danteum spreads like a shadow in times of modern brightness. A kind of non-architecture as an existential point, which may be said to be ¿not totally¿ and which exception makes everything exist. In this landscape of non-arranged notions, the coexistence of architectonic and non-architectonic terms gives rise to paradoxes and antonyms very propitious for the analysis of uncertainties spread under the paradigmatic dominance of modern architecture. 4. The most relevant is not the search of the author, but the process of this search. Lingeri and Terragni are only suspicious and respond only to research interests. The research process has not followed a straight line in the attempt to examine the Danteum project anatomy, which has needed a dramatic and quasi mythological element in order to disguise its modern face. The result is a mosaic of half defined and half blurred, with reflexes, drafts, notes. In this context, history occurs like the movement of a scalpel in the dissection of a corpse. ; 1. Mayo de 1938. Rino Valdameri, presidente de la Academia de Brera, y el senador Alessandro Poss, proponen a las autoridades en Roma un monumento en homenaje al máximo poeta de los italianos. El encargo es encomendado a los arquitectos Pietro Lingeri y Giuseppe Terragni, el nombre del proyecto: el Danteum. En Octubre de 1938, los arquitectos y los promotores son convocados para el jueves 10 de Noviembre, hora 17:30, al Palacio Venecia para presentar el proyecto a Benito Mussolini, Capo de Governo. El proyecto es bien recibido, aprobándose su continuación. En mayo de 1939, es suspendida una segunda audiencia con el Duce, la posible realización del proyecto se ve amenazada. El 1 de septiembre de 1939 Alemania invade Polonia. A los continuos pedidos de esta segunda audiencia, el 4 de septiembre de este mismo año, los promotores reciben la respuesta del Segretario particolare di S.E. il Capo del Governo, anunciando que el actual momento no es el más oportuno. Un día después Terragni es movilizado y asignado al III regimiento de artillería de cuerpo de armada en Cremona; aún así se realizarán algunas modificaciones al proyecto hasta la primavera de 1941. A finales de enero de 1943, Terragni es repatriado e internado en el hospital militar de Cesenático. El 19 de julio, inesperadamente, Terragni muere a pocos metros de su casa. El 25 de julio, el rey Victor Manuel III hace apresar a Mussolini. Durante el bombardeo aliado de 1944, Lingeri salva los originales del proyecto del Danteum de ser destruidos: una serie de dibujos con técnica mixta, acuarela y tinta sobre papel blanco de Fabriano, montados sobre paneles rígidos a escala 1:100, y una maqueta realizada en madera, escala 1:50. El 28 de abril de 1945 Mussolini es capturado y fusilado por los partisanos. En septiembre de 1957, el Danteum es publicado por primera vez en una revista. 2. El argumento central del proyecto establece una correspondencia compositiva con la Divina Commedia, desde las estructuras comunes -proporciones y medidas- que la obra de arquitectura puede sustraer del poema de Dante. Tal dependencia entre arquitectura y literatura ha relegado al Danteum, de tanto en tanto, más allá del confín del territorio arquitectónico, provocando su destierro del centro hermético de la especificidad arquitectónica, condenado por sus implicaciones contra la autonomía de la disciplina, y por esa gesticulación tan suya y excesiva de histrión. 3. ¿Por qué un objeto híbrido, de género incómodo, y no las obras mayores de su autor? El intersticio que se crea con el Danteum no alude a la arquitectura como un producto estacionario, cerrado y finito, sino como una transición entre lo unívocamente formal y el vértigo narrativo. En esta liminidad, que une y separa lo arbitrario de lo estrictamente disciplinar, está la voluntad de nuestra elección. Con su lógica fronteriza el Danteum se despliega como una sombra en tiempos de claridad moderna. Una especie de no-arquitectura como punto existencial del que puede decirse que no es "del todo" y que además hace existir el todo por su excepción. En este paisaje de nociones no concertadas, la coexistencia de términos arquitectónicos y no arquitectónicos da lugar a paradojas y antinomias muy propicias para el análisis de las incertidumbres sembradas en el dominio paradigmático de la arquitectura moderna. 4. Lo importante no es la búsqueda del autor, sino la procesualidad de esa búsqueda, de ese acto. Lingeri y Terragni quedan como meros sospechosos, y a veces respondiendo sólo a intereses narrativos. No hay ninguna dirección lineal en el intento de examinar la anatomía de este acontecimiento fenomenal que ha precisado un elemento dramático y cuasi mitológico para encubrir su vestidura moderna. Lo que queda es un mosaico de figuras medio definidas medio borrosas, de reflejos, de apuntes, de notas. En este apenas, la historia tiene lugar como el movimiento de un bísturi en la disección de un cadáver. ; Postprint (published version)

Les tècniques computacionals de simulació han permès la introducció de metodologies de modelització per analitzar sistemes complexes a través d'experimentació virtual, i així avaluar l'impacte d'intervencions sobre els serveis sanitaris. La simulació d'esdeveniments discrets és una tècnica ben coneguda en la investigació operativa que s'ha desenvolupat principalment en l'àmbit de la investigació militar i els sistemes de producció industrial. En l'àmbit mèdic, els models de Markov i els arbres de decisió han estat utilitzats de manera extensa a pesar de les seves limitacions per a reproduir els problemes sanitaris acuradament. La simulació d'esdeveniments discrets està guanyant popularitat degut a la seva flexibilitat per a representar sistemes reals tenint en compte les característiques dels pacients i l'escassedat de recursos present en la provisió de serveis sanitaris. Aquesta tècnica s'ha utilitzat per a analitzar problemes relacionats amb la gestió de recursos sanitaris, però les seves possibilitats per a analitzar problemes més amplis relacionats amb la dinàmica de les poblacions s'han explorat poc. Tradicionalment, les necessitats i la demanda de serveis sanitaris s'han analitzat per separat. En l'aplicació que es presenta es va analitzar la resposta del sistema sanitari tant a la població amb necessitat de cirurgia com als pacients inclosos en llistes d'espera. En aquest sentit, la principal contribució d'aquesta tesi és l'aplicació de la simulació d'esdeveniments discrets a la recerca en serveis sanitaris des d'un punt de vista epidemiològic. A més, el model és complexe a nivell estadístic degut a la diversitat de fonts d'informació i de característiques de les dades que defineixen la informació principal d'entrada; les lleis del sistema modelat van requerir una metodologia ad hoc específica per a recollir i processar aquesta informació per tal de generar les dades d'entrada que necessitava el model de simulació. Per tant, una part important d'aquest treball s'ha dedicat a desenvolupar aquesta metodologia d'anàlisi de les dades d'entrada. Es va construir un model de simulació d'esdeveniments discrets per a analitzar les necessitats i la demanda de cirurgia de cataractes en el sector públic de Catalunya. El model reprodueix el procés de la cirurgia de cataractes, des de la incidència de necessitat de cirurgia, passant per la demanda, la inclusió en una llista d'espera i la cirurgia finalment. Es descriu detalladament la metodologia per a analitzar les dades d'entrada del model. Els paràmetres del model es van estimar utilitzant diferents fonts d'informació, tant bases de dades administratives com de recerca. Es descriu detalladament la implementació del model en el software SIMUL8 i com es pot enllaçar amb Excel per a fer el model més amigable per a usuaris no experts en simulació. Es van realitzar diverses anàlisis de sensibilitat per a avaluar l'impacte de la variabilitat de les estimacions dels paràmetres d'entrada (validació), l'impacte de diferents estratègies de gestió de la llista d'espera segons diferents escenaris de temps mitjà d'espera, i per a avaluar la transferibilitat de la metodologia. Per a avaluar la transferibilitat es va aplicar la metodologia per a calcular els paràmetres d'entrada a diferents àmbits (altres Comunitats Autònomes d'Espanya). Els resultats del model es van utilitzar per a analitzar variacions geogràfiques en l'impacte d'introduir un sistema de priorització de llistes d'espera. A més, es va combinar la informació de les Comunitats Autònomes per a utilitzar el model per a avaluar el volum de necessitat de cirurgia de cataractes a Espanya segons diferents criteris d'indicació de cirurgia. La transferibilitat de la metodologia a d'altres cirurgies electives es va avaluar adaptant el model per a analitzar necessitats i demanda de cirurgia de pròtesi de genoll a Espanya. L'estudi de les necessitats i la demanda de serveis sanitaris és rellevant en la mesura que s'observa un volum important de necessitats no ateses. La diferència entre la necessitat i la provisió de serveis pot ser massa gran per poder-la resoldre, però la utilització de models que avaluïn l'impacte de modificacions en la quantitat de recursos utilitzats o l'impacte de polítiques sanitàries en la gestió de la necessitat i la demanda de serveis és útil en la presa de decisions sanitàries. ; Computer simulation techniques have allowed the introduction of modeling methodologies that analyze complex systems through virtual experimentation to assess the potential impact of interventions on health services. Discreteevent simulation is a well-known technique in operations research, and has mainly been developed in the context of military research and manufacturing systems. In the medical setting, Markov models and decision trees have been extensively used despite their limitations in reproducing healthcare problems accurately. Discrete-event simulation is gaining popularity because of its flexibility in representing real systems by taking into account patient characteristics and the scarcity of resources present in health services provision. This technique has been used to analyze problems related to healthcare resource management, but its possibilities to analyze larger problems related to population dynamics have been hardly explored. Traditionally, needs and demand for health services have been analyzed separately. In the present application, the response of the health system to both the population with need for surgery and to the patients included on a waiting list was analyzed. In this sense, the main contribution of this thesis is the application of discrete-event simulation to health services research from an epidemiologic point of view. Moreover, the model was statistically complex because the variety of sources and characteristics of data defining the main inputs and rules of the modeled system asked for a specific ad hoc methodology to collect and process them to generate the inputs that the simulation model needs. Therefore a relevant part of this work has been devoted to develop such input data analysis methodology. A discrete-event simulation model was built for needs and demand for cataract surgery in the Catalan public sector. The model reproduced the process of cataract surgery, from incidence of need for surgery, through demand, inclusion on a waiting list and surgery. The input data analysis methodology was described in detail. The model's parameters were estimated from several sources, including administrative and research databases. The implementation of the model in the software SIMUL8 and its link to Excel to make the model user-friendly for nonexpert users were described in detail. Several sensitivity analyses were performed to assess the impact of the variability of the input estimations (validation), the impact of different waiting list management strategies according to different scenarios of mean waiting time, and to assess the transferability of the methodology. Transferability was evaluated by applying the methodology for calculating the input values to different settings (other regions of Spain). Then, results of the model were used to analyze geographical variations of the impact of introducing a waiting list prioritization system. Moreover, information of the different regions was combined to use the model to assess the volume of need for cataract surgery in Spain according to different indication criteria for surgery. Transferability of the methodology to other elective surgeries was assessed by adapting the model to analyze needs and demand for knee replacement in Spain. Study of needs and demand for health services is important since substantial unmet needs are observed. The gap between needs and services provision may be too great to be resolved, but models that assess the impact of changes on the amount of resources used or the impact of health policies on the management of need and demand are useful in healthcare decision-making. ; Postprint (published version)

Problematización de las áreas grisesLa problematización de algunos aspectos de la teoría de la transición, que permite posteriormente conducir el estudio hacia la reformulación de ciertos supuestos, se estructurará en torno a la segunda variable explicativa: la insatisfacción del estado contendiente con el orden impuesto por el estado dominante.La transición en las capacidades de poder, u oportunidad de cambio, no puede considerarse un área gris. Se han hecho críticas a la metodología utilizada para medir el poder, pero en general se ha concedido que el PNB resulta aceptable a la hora de ubicar estados dominantes, contendientes y señalar los momentos en que efectivamente existe una transición en la distribución de poder. Siendo una variable esencialmente cuantitativa, existe una extensa producción estadística que permite verificarla empíricamente.La voluntad de cambio –según la tipología de Lemke-, o el grado de insatisfacción, es quizá el factor más controvertido de la teoría. Aún así, su relevancia es total. Recuérdese que –junto con la oportunidad- el grado de insatisfacción es una condición sine qua non para la posibilidad de conflicto. No basta con que un estado supere a otro en poder; el contendiente debe tener intenciones revisionistas hacia el status quo. Si se comprueba que existen las dos variables, la posibilidad de un conflicto se vuelve plausible. Según Lemke & Werner: "…a rising state is dissatisfied if the prospective rules of the system that it would like to impose are different 'enough' from those already established by the current dominant country. A dissatisfied challenger presented with the opportunity to wage war with a reasonable chance of winning would do so and thus could not be deterred. A rising state is considered satisfied if its favored rules are similar enough to those of the dominant country that the costs of war are not worth the marginal adjustment to the status quo." Extrañamente, el factor de insatisfacción no ha recibido la atención adecuada en el proceso de desarrollo y complemento teórico iniciado en la década de 1950 con las primeras formulaciones de Organski, abriendo una brecha de inconsistencia importante en la teoría.Aún así, existen algunos intentos de refinar el concepto. Werner & Kugler han encarado el tema a través del establecimiento de un indicador de los desarrollos militares y armamentistas de los contendientes. Cuando el contendiente tiene un desarrollo armamentista más fuerte que el del dominante se podría afirmar que está insatisfecho o comprometido a cambiar el orden establecido, "…an extraordinary military buildup in wich the challenger is enlarging its arsenal at a faster rate than the dominant country indicates that the challenger is committed to changing the relevant status quo". Otros análisis en este misma línea son: el estudio de los portafolios de alianzas estructurado por Kim, las comparaciones de la similitud de las estructuras domésticas de Lemke, entre otros. Ninguno de los anteriores resulta exhaustivo. A su vez, todos suponen intentos para medir la insatisfacción sin ir a la naturaleza del problema. ¿Cómo se puede medir un concepto que aun no ha sido definido y entendido cabalmente? No parece muy redituable desarrollar la metodología para identificar los grados de insatisfacción estatales, si se mantienen importantes agujeros en su concepción más elemental. A continuación se señalarán cuáles son los problemas más notables.En primer lugar, y de manera necesariamente precedente al análisis de la insatisfacción, se debe definir qué se entiende por status quo. La relación entre el orden establecido y el estado dominante y contendiente es esencial. El estado dominante tiene que verse favorecido por el status quo; los beneficios se desprenden de la condición del dominante como creador y –cuando menos- primus inter pares en dicho orden. Según Organski: "a hegemon always benefits disproportionately from any enterprises involving less powerful states, be they friendo or foes". Dos aclaraciones surgen de lo anterior. La primera se desprende automáticamente de la cita de Organski: si el hegemón se va a beneficiar siempre desproporcionadamente, se debe aceptar que el contendiente va a resultar siempre perjudicado en mayor o menor grado. Recuérdese, que como se vio anteriormente, el estado contendiente se siente insatisfecho si las reglas que éste querría imponer –es decir, que mejor encajan con sus objetivos- son diferentes de las que le impone el status quo. Ergo, si el ascendente se verá perjudicado necesariamente, es –cuando menos- complicado afirmar que podría sentirse satisfecho, como avala la teoría.En segundo lugar, existe una evidente falta de claridad sobre cuáles son los beneficios que obtiene el dominante; según Oneal: "The basic problem is that power transition theory does not identify what benefits the international system provides to states and over wich they might fight." Si no se definen cuidadosamente cuáles son estos beneficios, ¿cómo saber si el poder ascendente estará insatisfecho o no con ellos?, más aún ¿cómo saber siquiera si son una variable a considerar por parte del contendiente? Oneal propone –razonablemente- que dichos beneficios aparezcan en el ámbito del poder y la riqueza de un país, estipulación que parece ser aceptada por la literatura. Pero aquí surge otra grieta intelectual. Si efectivamente los beneficios se vuelcan sobre la riqueza y el poder, por qué un estado que está creciendo indefectiblemente a tasas más altas que el dominante, es decir, que está aumentando exitosamente su poder, debería sentirse insatisfecho. Un estado ascendente estaría cumpliendo con sus objetivos nacionales. Esta es una inconsistencia que no ha podido ser refutada, limitando seriamente el poder explicativo de la teoría.Un segundo sector gris es el alcance explicativo de la variable de satisfacción. La condición sine qua non de la insatisfacción del contendiente como causa de la guerra puede ser calificada de reduccionista. Este reduccionismo deriva en dos situaciones comprometedoras. La primera de ellas es que únicamente el contendiente va a ser tenido en cuenta como posible agresor. La insatisfacción sólo puede venir del estado ascendente –el dominante debe estar satisfecho ya que es él quien impone el orden-, ergo, el conflicto depende exclusivamente de las intenciones de aquel. Se ve al hegemónico como una variable dada, que solamente puede reaccionar una vez que el otro hizo estallar el conflicto. Este supuesto teórico no parece muy acertado; dejar por fuera al estado más poderoso del sistema y quién administra el status quo equivale a tapar el sol con la mano. El segundo problema es la monocausalidad de la insatisfacción. En este caso, monocausalidad no supone que exista un solo factor que conduzca a un estado a la insatisfacción, esto sería una falacia; se podrían exponer un sinnúmero de razones que incentivarían una concepción revisionista del sistema. La clave está en la condición de internas de las causas de la insatisfacción. Asumir que la insatisfacción con el status quo –resultado de los perjuicios que le genera- es una consecuencia directa de la forma en que el ascendente entiende el orden resulta complejo. Se realiza un análisis estático de los objetivos del contendiente comparándolos con las reglas del status quo. A su vez, éstos devienen únicamente de prerrogativas internas, no se tiene en cuenta la inevitable interacción del contendiente con el dominante. A modo de ejemplo se podría argumentar que de haber sido otro el estado dominante durante el ascenso del Tercer Reich -un hegemón que no habría aplicado una política de appeasement como lo hizo Gran Bretaña- los objetivos de Hitler podrían haberse tornado limitados, pudiendo llegar a un estado de satisfacción o e su defecto disminuir la agresividad del régimen nazi. En otras palabras, desestimar la interacción entre dominante y contendiente deja a la teoría en una situación de vulnerabilidad considerable.Presentados los problemas del factor de insatisfacción podemos avanzar a la siguiente sección en la que se proponen algunas ideas para reformular y complementar la teoría de la transición *Candidato a la Maestría en Estudios Internacionales,Universidad Torcuato di TellaBuenos Aires, Argentina

Les tècniques computacionals de simulació han permès la introducció de metodologies de modelització per analitzar sistemes complexes a través d'experimentació virtual, i així avaluar l'impacte d'intervencions sobre els serveis sanitaris. La simulació d'esdeveniments discrets és una tècnica ben coneguda en la investigació operativa que s'ha desenvolupat principalment en l'àmbit de la investigació militar i els sistemes de producció industrial. En l'àmbit mèdic, els models de Markov i els arbres de decisió han estat utilitzats de manera extensa a pesar de les seves limitacions per a reproduir els problemes sanitaris acuradament. La simulació d'esdeveniments discrets està guanyant popularitat degut a la seva flexibilitat per a representar sistemes reals tenint en compte les característiques dels pacients i l'escassedat de recursos present en la provisió de serveis sanitaris. Aquesta tècnica s'ha utilitzat per a analitzar problemes relacionats amb la gestió de recursos sanitaris, però les seves possibilitats per a analitzar problemes més amplis relacionats amb la dinàmica de les poblacions s'han explorat poc. Tradicionalment, les necessitats i la demanda de serveis sanitaris s'han analitzat per separat. En l'aplicació que es presenta es va analitzar la resposta del sistema sanitari tant a la població amb necessitat de cirurgia com als pacients inclosos en llistes d'espera. En aquest sentit, la principal contribució d'aquesta tesi és l'aplicació de la simulació d'esdeveniments discrets a la recerca en serveis sanitaris des d'un punt de vista epidemiològic. A més, el model és complexe a nivell estadístic degut a la diversitat de fonts d'informació i de característiques de les dades que defineixen la informació principal d'entrada; les lleis del sistema modelat van requerir una metodologia ad hoc específica per a recollir i processar aquesta informació per tal de generar les dades d'entrada que necessitava el model de simulació. Per tant, una part important d'aquest treball s'ha dedicat a desenvolupar aquesta metodologia d'anàlisi de les dades d'entrada. Es va construir un model de simulació d'esdeveniments discrets per a analitzar les necessitats i la demanda de cirurgia de cataractes en el sector públic de Catalunya. El model reprodueix el procés de la cirurgia de cataractes, des de la incidència de necessitat de cirurgia, passant per la demanda, la inclusió en una llista d'espera i la cirurgia finalment. Es descriu detalladament la metodologia per a analitzar les dades d'entrada del model. Els paràmetres del model es van estimar utilitzant diferents fonts d'informació, tant bases de dades administratives com de recerca. Es descriu detalladament la implementació del model en el software SIMUL8 i com es pot enllaçar amb Excel per a fer el model més amigable per a usuaris no experts en simulació. Es van realitzar diverses anàlisis de sensibilitat per a avaluar l'impacte de la variabilitat de les estimacions dels paràmetres d'entrada (validació), l'impacte de diferents estratègies de gestió de la llista d'espera segons diferents escenaris de temps mitjà d'espera, i per a avaluar la transferibilitat de la metodologia. Per a avaluar la transferibilitat es va aplicar la metodologia per a calcular els paràmetres d'entrada a diferents àmbits (altres Comunitats Autònomes d'Espanya). Els resultats del model es van utilitzar per a analitzar variacions geogràfiques en l'impacte d'introduir un sistema de priorització de llistes d'espera. A més, es va combinar la informació de les Comunitats Autònomes per a utilitzar el model per a avaluar el volum de necessitat de cirurgia de cataractes a Espanya segons diferents criteris d'indicació de cirurgia. La transferibilitat de la metodologia a d'altres cirurgies electives es va avaluar adaptant el model per a analitzar necessitats i demanda de cirurgia de pròtesi de genoll a Espanya. L'estudi de les necessitats i la demanda de serveis sanitaris és rellevant en la mesura que s'observa un volum important de necessitats no ateses. La diferència entre la necessitat i la provisió de serveis pot ser massa gran per poder-la resoldre, però la utilització de models que avaluïn l'impacte de modificacions en la quantitat de recursos utilitzats o l'impacte de polítiques sanitàries en la gestió de la necessitat i la demanda de serveis és útil en la presa de decisions sanitàries. ; Computer simulation techniques have allowed the introduction of modeling methodologies that analyze complex systems through virtual experimentation to assess the potential impact of interventions on health services. Discreteevent simulation is a well-known technique in operations research, and has mainly been developed in the context of military research and manufacturing systems. In the medical setting, Markov models and decision trees have been extensively used despite their limitations in reproducing healthcare problems accurately. Discrete-event simulation is gaining popularity because of its flexibility in representing real systems by taking into account patient characteristics and the scarcity of resources present in health services provision. This technique has been used to analyze problems related to healthcare resource management, but its possibilities to analyze larger problems related to population dynamics have been hardly explored. Traditionally, needs and demand for health services have been analyzed separately. In the present application, the response of the health system to both the population with need for surgery and to the patients included on a waiting list was analyzed. In this sense, the main contribution of this thesis is the application of discrete-event simulation to health services research from an epidemiologic point of view. Moreover, the model was statistically complex because the variety of sources and characteristics of data defining the main inputs and rules of the modeled system asked for a specific ad hoc methodology to collect and process them to generate the inputs that the simulation model needs. Therefore a relevant part of this work has been devoted to develop such input data analysis methodology. A discrete-event simulation model was built for needs and demand for cataract surgery in the Catalan public sector. The model reproduced the process of cataract surgery, from incidence of need for surgery, through demand, inclusion on a waiting list and surgery. The input data analysis methodology was described in detail. The model's parameters were estimated from several sources, including administrative and research databases. The implementation of the model in the software SIMUL8 and its link to Excel to make the model user-friendly for nonexpert users were described in detail. Several sensitivity analyses were performed to assess the impact of the variability of the input estimations (validation), the impact of different waiting list management strategies according to different scenarios of mean waiting time, and to assess the transferability of the methodology. Transferability was evaluated by applying the methodology for calculating the input values to different settings (other regions of Spain). Then, results of the model were used to analyze geographical variations of the impact of introducing a waiting list prioritization system. Moreover, information of the different regions was combined to use the model to assess the volume of need for cataract surgery in Spain according to different indication criteria for surgery. Transferability of the methodology to other elective surgeries was assessed by adapting the model to analyze needs and demand for knee replacement in Spain. Study of needs and demand for health services is important since substantial unmet needs are observed. The gap between needs and services provision may be too great to be resolved, but models that assess the impact of changes on the amount of resources used or the impact of health policies on the management of need and demand are useful in healthcare decision-making. ; Postprint (published version)

Modeling and control of switched-mode dc-dc converters has occupied a center stage in the field of modern power electronics due to their widespread military and industrial applications. Averaged modeling is most commonly applied as an effective tool to analyze dynamic behavior of a converter and to get physical insights into various dynamical phenomena. State-space averaged models are widely accepted in practice mainly because of their simplicity, generality and demonstrated practical utility. Various averaged models have been presented in literature; however, some fundamental questions regarding averaging methodologies still lack satisfactory answers. These unresolved modeling issues are primarily related to their practical validation, inclusion of circuit parasitics and their application to the control-loop design. One of the primary concerns of this thesis is to study and evaluate the performance of averaged modeling of dc-dc converters from control perspective. In particular, the main emphasis is placed on the theoretical and experimental investigation of averaged modeling in discontinuous conduction mode (DCM). Various analytical averaged models of different orders, presented in literature, are reformulated in this thesis by including all appropriate parasitics. Parasitics are introduced to take into account those phenomena which can possibly induce instability. Then, the validities of these averaged models are experimentally examined by comparing analytical results with experimental results measured from a hardware prototype. As far as control is concerned, stability is of prime importance in any dc voltage regulation system. However, closed-loop stability is not guaranteed if a low-pass filter is present at converter-input. The origin of this problem lies in the filter interactions with the negative dynamic resistance behavior of the dc-dc converter input port. Literature provides a gateway to solve this issue and proposes a ?passive? solution to damp the input-filter oscillations. Although exact values of the required damping resistance can be determined using an ideal converter model, this value is not systematically confirmed through experiments. In this thesis small-signal control-to-output transfer functions are used to systematically formulate some design rules to avoid instability. Safe operating regions are identified in terms of damping-circuit parameters and this approach is subsequently extended to the case of cascade converters. Throughout this study the small-signal averaged modeling is used for the stability analysis. Although adding adequate resistance to the filter can solve instability problem, one drawback for which passive damping is commonly criticized is the undesirable power dissipation in the damping resistors. To properly investigate its adverse impact on conversion efficiency, these damping losses are quantified in this thesis. A detailed theoretical power-loss analysis is presented under varying operating conditions followed by its experimental verification. Obtained results are generalized for all fundamental topologies. One of the main themes of this dissertation is the development of a control solution for the stability of dc-dc converter in presence of input filter, hence avoiding the use of dissipative damping. To achieve this objective, this thesis suggests the use of full state-feedback control with pole-placement technique. An augmented state-space averaged model is used to design the controller which combines state-feedback with PI-control loop. First of all a theoretical approach is presented. Then the effectiveness of the proposed control algorithm is demonstrated with simulation studies. It appears that an adequate level of dynamic performance under large perturbations can be achieved by using a varying gain state-feedback. A pseudo large-signal stability analysis is also performed with the help of this technique. Importantly, this control strategy assures stability of the system without using any passive components in the filter circuit and thus avoiding undesirable losses. An alternate control scheme, chosen from the literature, is also discussed for filter-converter system stability. This scheme is based upon sliding-mode control and Lyapunov function approach. Its dynamic performance is compared with that of the full state-feedback controller proposed in this thesis while explaining pros and cons of both control strategies. ; La modélisation et la commande des convertisseurs de type continu/continu occupent une place de plus en plus importante dans le domaine de l'électronique de puissance. La « modélisation moyenne » est la plus courante. C'est un outil efficace permettant d'analyser le comportement dynamique global d'un convertisseur et de dégager les principaux phénomènes physiques intervenant sur ce comportement. Les modèles moyennés en espace d'état sont largement acceptées dans la pratique, principalement de par leur simplicité, leur généralité et leur utilité pratique qui n'est plus à démontrer. Divers modèles moyennés ont été présentés dans la littérature spécialisée. Il subsiste cependant quelques questions fondamentales en ce qui concerne les méthodologies moyennes qui n'apportent pas toujours une réponse satisfaisante. Ces problèmes non résolus de modélisation touchent essentiellement à la validation pratique, à l'intégration des parasites du circuit électrique réel et à l'application à la conception de la boucle de commande. L'une des principales préoccupations de cette thèse est d'étudier et d'évaluer les performances de la modélisation moyenne des convertisseurs dc/dc en vue de leur commande. En particulier, l'accent est mis sur l'étude théorique et expérimentale des modèles moyennés en mode de conduction discontinu (DCM). Divers modèles moyens analytiques de différents ordres, présentés dans la littérature, sont reformulés en incluant les parasites. Leur validité relative est examinée expérimentalement par rapport à un prototype physique. En ce qui concerne la commande, la stabilité est d'une importance capitale dans tout système de régulation de tension. Toutefois, assurer la stabilité en boucle fermée n'est pas évident en présence d'un filtre en entrée du convertisseur. L'origine de ce problème réside dans l'interaction du filtre avec le comportement du convertisseur dc/dc de type « résistance dynamique négative ». La littérature fournit une solution pour résoudre ce problème et propose une solution « passive » pour amortir les oscillations liées au filtre d'entrée. La valeur de la résistance d'amortissement nécessaire peut être déterminée en utilisant un modèle de convertisseur idéal. Toutefois, cette valeur n'est pas systématiquement confirmée par l'expérience. Dans cette thèse, des fonctions de transfert en régime de petits signaux sont utilisés pour formuler systématiquement des règles de dimensionnement pour éviter l'instabilité. Les régions de la stabilité sont déterminées en fonction des paramètres du circuit d'amortissement. Cette approche est étendue au cas de convertisseurs en cascade. Tout au long de cette étude, la modélisation moyenne en petit-signal est utilisée pour l'analyse de la stabilité. Bien que l'ajout d'une résistance suffisante assure la stabilité, l'amortissement passif est critiquable à cause de pertes énergétiques indésirables dans les résistances utilisées. Afin d'en étudier les retombées sur le rendement du convertisseur, les pertes dues à l'amortissement sont quantifiées d'une manière plus systématique dans cette thèse. Une analyse théorique de ces pertes est présentée dans diverses conditions de fonctionnement. La validation expérimentale est toujours présente. Les résultats obtenus sont généralisés à toutes les topologies fondamentales de convertisseurs. L'un des principaux thèmes de cette thèse touche au développement d'une commande assurant la stabilité du convertisseur dc/dc avec son filtre d'entrée sans utiliser d'amortisseur dissipatif. Afin d'atteindre cet objectif, une solution avec commande par retour d'état et placement des pôles est proposée. Un modèle moyen d'ordre élevé est mis en place pour concevoir un correcteur qui combine le retour d'état avec une boucle PI. L'efficacité de l'algorithme de commande proposé est démontrée par des résultats de simulation. Il apparaît que des performances dynamiques intéressantes peuvent être atteintes en présence de grandes perturbations en utilisant un retour d'état avec gains variables. En outre, cette stratégie de commande assure la stabilité du système sans composant passif additionnel dans le filtre d'entrée et sans pertes supplémentaires. Ensuite, dans un deuxième temps, une commande par mode-glissement basée sur l'approche de la fonction de Lyapunov est discutée, laquelle est présentée dans la litérature pour l'ensemble abaisseur-filtre. Nous discutons les performances de la commande par retour d'état, proposée dans cette thèse, comparées à celles d'un contrôleur mode-glissant.

A side-looking sonar was constructed for military purposes during World War II as a development of forward-search sonars used for detection of foe submarines hiding motionless on a seabed. An unexpected career of sidescan sonars began with their implementation in marine geology. A sonar ability to recognise sediment roughness and consequently grain size allowed significant opportunities for sediment mapping, which were spatially more precise than the ones performed by sediment sampling. In addition, an acoustic shadow caused by close-seabed scanning over troughs and ridges allowed easier interpretation of the bottom morphology. These revolutionary features opened new ways of underwater exploration. Some multi-disciplinary applications of sonographs on continental shelves are presented in the introduction of this work after a technical description of a sidescan sonar system, and sonograph processing issues. The main objective of this work is to discuss three case studies on sidescan sonar applications in seabed dynamics research. Each of the study was constructed as a separate research paper qualified for prestigious journals and thus, the introductory part of this work is a descriptive supplement of information enclosed in the presented manuscripts. A case study from the southern Vietnamese shelf is focused on sand dunes mapping on the basis of not mosaicked sonographs. It was the first investigation on bedforms from this area; however it contains data only from the end of the winter monsoon. The shelf area was divided into five zones grouping dunes of similar size, shape and orientation. All located sand dunes higher than 1.5 m were described, summarized in a scatter plot of height/length ratio and thus compared to dunes observed on other shelves. The dunes orientation corresponded to the overall South China Sea circulation pattern during the winter monsoon. Therefore, the possibility of dunes mobilisation was investigated with the help of empirical equations predicting sediment transport. Depth-integrated velocities necessary to put sediment forming dunes in motion were calculated for distinguished zones. The results were discussed with hydrodynamic in-situ measurements of other authors and it was concluded that most of the investigated dunes were likely to migrate actively following the monsoon circulation. A case study from the Baltic Sea is a rare example of an investigation focused on changes in the morphology of pits created by anchor hopper dredging of marine sand and gravel aggregates. By means of sidescan sonar and multi-beam echosounder data, a six-year evolution of four pits was presented. In the case of three pits dredged in a sandy seabed faster smoothing of edges and infilling rates larger than in the case of a pit dredged in gravel were clearly observed. The edges of the gravel pit were expanding due to collapsing of the side-walls. The infilling of the pit was investigated based on approximations of pit depth by single- and multi-beam echosoundings, as well as acoustic shade length in the sonographs. Earlier studies of other authors on this pit allowed plotting a curve of infilling rate over six years of pit evolution. The filling clearly slowed down over time and the reasons for that are discussed in this paper. The sand screened in the dredging process surrounded the investigated pit and its backscatter values in sonographs clearly separate it from the gravel seabed. The area covered by the screened sand fraction was monitored and appeared to be decreasing in time. Hydrological data showed the possibility of frequent mobilisation of this fraction and therefore indicated it as the main source for pit infilling. A case study from the North Sea presents a unique approach of conversion analogue sidescan sonar data into digital, geo-referenced form in order to present morphological stability and birth of sorted bedforms. The analogue mosaic was geo-coded in a DECCA navigation system in 1977. DECCA system technology was described thoroughly and a study of the spatial errors was presented for accurate geo-referencing of the mosaic. Image warping by rubber-sheeting method was performed to compare old sonographs of a sorted bedform with sonographs from 2002. A continuation study of Dr. Markus Diesing et al. additionally contains a multi-beam backscatter mosaic from 2003 as a comparison data-set. The morphological stability of the bedforms over time was discussed in the paper and compared to worldwide examples. Hydrodynamic conditions influencing the bedforms were presented and a significant role of the tidal currents in shaping the sorted bedforms was demonstrated. An asymmetry of a newly appeared sorted bedform, however, was probably related rather to high energy storm events. Even though the sidescan sonar data were collected from three different seas for three different case studies in three different scales, sonographs proved to be a valuable tool in each of the cases. Minor limitations of sidescan sonar systems and options for applying other devices for the same types of investigations are discussed in the end of this work. ; Während des Zweiten Weltkrieges wurde für militärische Zwecke zum Aufspüren feindlicher Unterseeboote, die die sich bewegungslos auf dem Meeresgrund versteckten, ein seitwärts schauendes Sonar als Fortentwicklung des vorwärts schauenden Sonars gebaut. Eine unerwartete Karriere dieses Seitensicht-Sonars begann mit seiner Einführung in der Marinen Geologie. Die Fähigkeit des Sonars, die Sedimentrauhigkeit und infolgedessen die Korngröße zu erkennen, eröffnete bedeutende Möglichkeiten in der Sedimentkartierung mit einer räumlich besseren Auflösung als sie durch Probennahmen zu erreichen ist. Zusätzlich erlaubt ein akustischer Schatten, der durch bodennahes Überfahren von Vertiefungen und Erhebungen verursacht wird, eine einfachere Interpretation der Morphologie des Meeresgrundes. Diese revolutionären Eigenschaften öffneten neue Wege der Unterwassererforschung. Einige multidisziplinäre Anwendungen von Sonographen auf Kontinentalsockeln werden in der Einleitung zu dieser Arbeit neben technischen Besonderheiten des Seitensicht-Sonar-Systems und Implikationen bei der Verarbeitung von Sonographie-Daten beschrieben. Die Hauptzielsetzung dieser Arbeit ist es, drei Fallstudien der Anwendung eines Seitensicht-Sonars in Meeresgrunddynamikstudien darzustellen. Jede der Studien wurde für anerkannte Journale verfasst oder angenommen, der einleitende Teil dieser Arbeit ist eine beschreibende Ergänzung der Informationen in den vorgestellten Veröffentlichungen. Eine Fallstudie am Südvietnamesischen Kontinentalsockel ist auf die Kartierung der Sanddünen auf der Basis nicht zusammengesetzter Sonographie-Daten ausgerichtet. Es ist die erste Untersuchung von Bodenformen in diesem Gebiet, enthält jedoch nur Daten vom Ende des Wintermonsuns. Der Schelfbereich wurde in fünf Zonen eingeteilt, um Dünen ähnlicher Größe, Form und Orientierung zu gruppieren. Alle lokalisierten Sanddünen mit einer Höhe größer als 1.5 m wurden beschrieben und in ihrem höhen/längen Verhältnis in einem Scatterplot dargestellt, und auf diese Weise mit Dünen auf anderen Schelfen verglichen. Die Düneorientierung entspricht dem allgemeinen Zirkulationsschema der Südchinesischen See während des Wintermonsuns. Die Möglichkeit der Dünenmobilisierung wurde mit Hilfe empirischer Sedimenttransportgleichungen untersucht. Tiefengemittelte Strömungs­geschwindigkeiten, notwendig um Sedimente zur Bildung von Dünen in Bewegung zu setzen wurden berechnet. Die errechneten Ergebnisse wurden mit hydrodynamischen In-Situ Messungen anderer Autoren verglichen und es wurde gefolgert, dass die meisten untersuchten Dünen aktiv entsprechend der Monsunzirkulation wandern. Eine Fallstudie in der Ostsee ist ein seltenes Beispiel einer Untersuchung von Änderungen in der Morphologie von Gruben, die durch Nassbaggern von Marinen Sanden und Kiesen entstandenen sind. Mittels Seitensicht-Sonar und Fächerecholot-Daten wurde die Entwicklung von vier Gruben über sechs Jahre dargestellt. Im Falle dreier Gruben in sandigem Untergrund konnte eine deutlich höhere Abrundungsrate der Kanten und Sedimentation in den Gruben beobachtet werden als dies bei der Grube im Kiesbett der Fall war. Die Ränder der Grube im Kies änderten sich durch Abrutschen der Seitenwände. Sedimentation in den Gruben wurde basierend auf Näherungswerten der Grubetiefe durch Single-Beam-Echolot und Fächerecholot-Messungen, sowie akustische Schattenlänge in den Sonographie-Daten untersucht. Frühere Studien anderer Autoren an diesen Gruben ermöglichten es, die Sedimentationsrate über sechs Jahre darzustellen. Die Sedimentationsrate verlangsamte sich mit der Zeit deutlich, die Gründe hierfür werden in diesem Paper dargestellt. Der Sand, der während des Nassbaggerns ausgesiebt wurde, konnte im Umkreis der untersuchten Grube nachgewiesen werden, das Echo in den Sonographie-Daten war deutlich von dem des kiesigen Meeresgrundes zu unterscheiden. Der Bereich, der durch die ausgesiebte Sandfraktion bedeckt wurde, wurde beobachtet und verringerte sich mit der Zeit. Hydrologische Daten zeigen die Möglichkeit einer häufigen Mobilisierung dieser Sandfraktion, wodurch diese als hauptsächliche verantwortliche Quelle für die Sedimentation in den Gruben ausgemacht werden kann. Eine Fallstudie in der Nordsee stellt einen einmaligen Ansatz der Umwandlung von analogen Seitensicht-Sonar-Daten in digitale, georeferenzierte Form dar, um die morphologische Stabilität und die Entstehung von sortierten Bodenformen darzustellen. Das analoge Mosaik wurde 1977 im DECCA Navigationssystem geo-kodiert. Die DECCA System Technologie wurde gänzlich beschrieben und für die genaue Georeferenzierung des Mosaiks wurde eine Studie der räumlichen Fehler präsentiert. Eine Anpassung des Bildes wurde per "rubber – sheeting" Methode durchgeführt um historische Sonographie-Daten sortierter Bodenformen mit neuen Sonographie-Daten von 2002 zu vergleichen. Eine nachfolgende Studie von Dr. Markus Diesing et al. enthält zusätzlich ein "multi-beam backscattering" Mosaik von 2003 als vergleichendes Material. Die morphologische Stabilität der Bodenformen über die Zeit wird in dem Paper besprochen und mit weltweiten Beispielen verglichen. Die hydrodynamischen Umgebungsbedingungen der Bodenformen wurden dargestellt und eine bedeutende Rolle der Gezeiten-Strömungen auf diese festgestellt. Eine Asymmetrie neu entstandener sortierter Bodenformen hing vermutlich mit Sturmereignissen hoher Energie zusammen. Obwohl die Seitensicht-Sonar-Daten in drei unterschiedlichen Meeren für drei unterschiedliche Untersuchungen und in drei unterschiedlichen Maßstäben gesammelt wurden, waren die Sonographie-Daten in jedem der Fälle ein wertvolles Hilfsmittel. Die kleineren Beschränkungen von Seitensicht-Sonar-Systemen und die Möglichkeit der Anwendung anderer Systemen für die gleichen Studien werden im Ende dieser Arbeit diskutiert.

Recently, many new types of wireless networks have emerged for both civil and military applications, such as wireless sensor networks, ad hoc networks, among others. To improve the performance of these wireless networks, many advanced communication techniques have been developed at the physical layer. For both theoretical and practical purposes, it is important for a network researcher to understand the performance limits of these new wireless networks. Such performance limits are important not only for theoretical understanding, but also in that they can be used as benchmarks for the design of distributed algorithms and protocols. However, due to some unique characteristics associated with these networks, existing analytical technologies may not be applied directly. As a result, new theoretical results, along with new mathematical techniques, need to be developed. In this dissertation, we focus on the design of new algorithms and optimization techniques to study theoretical performance limits associated with these new wireless networks. In this dissertation, we mainly focus on sensor networks and ad hoc networks. Wireless sensor networks consist of battery-powered nodes that are endowed with a multitude of sensing modalities. A wireless sensor network can provide in-situ, unattended, high-precision, and real-time observation over a vast area. Wireless ad hoc networks are characterized by the absence of infrastructure support. Nodes in an ad hoc network are able to organize themselves into a multi-hop network. An ad hoc network can operate in a stand-alone fashion or could possibly be connected to a larger network such as the Internet (also known as mesh networks). For these new wireless networks, a number of advanced physical layer techniques, e.g., ultra wideband (UWB), multiple-input and multiple-output (MIMO), and cognitive radio (CR), have been employed. These new physical layer technologies have the potential to improve network performance. However, they also introduce some unique design challenges. For example, CR is capable of reconfiguring RF (on the fly) and switching to newly-selected frequency bands. It is much more advanced than the current multi-channel multi-radio (MC-MR) technology. MC-MR remains hardware-based radio technology: each radio can only operate on a single channel at a time and the number of concurrent channels that can be used at a wireless node is limited by the number of radio interfaces. While a CR can use multiple bands at the same time. In addition, an MC-MR based wireless network typically assumes there is a set of "common channels" available for all nodes in the network. While for CR networks, each node may have a different set of frequency bands based on its particular location. These important differences between MC-MR and CR warrant that the algorithmic design for a CR network is substantially more complex than that under MC-MR. Due to the unique characteristics of these new wireless networks, it is necessary to consider models and constraints at multiple layers (e.g., physical, link, and network) when we explore network performance limits. The formulations of these cross-layer problems are usually in very complex forms and are mathematically challenging. We aim to develop some novel algorithmic design and optimization techniques that provide optimal or near-optimal solutions. The main contributions of this dissertation are summarized as follows. 1. Node lifetime and rate allocation We study the sensor node lifetime problem by considering not only maximizing the time until the first node fails, but also maximizing the lifetimes for all the nodes in the network. For fairness, we maximize node lifetimes under the lexicographic max-min (LMM) criteria. Our contributions are two-fold. First, we develop a polynomial-time algorithm based on a parametric analysis (PA) technique, which has a much lower computational complexity than an existing state-of-the-art approach. We also present a polynomial-time algorithm to calculate the flow routing schedule such that the LMM-optimal node lifetime vector can be achieved. Second, we show that the same approach can be employed to address a different but related problem, called LMM rate allocation problem. More important, we discover an elegant duality relationship between the LMM node lifetime problem and the LMM rate allocation problem. We show that it is sufficient to solve only one of the two problems and that important insights can be obtained by inferring the duality results. 2. Base station placement Base station location has a significant impact on sensor network lifetime. We aim to determine the best location for the base station so as to maximize the network lifetime. For a multi-hop sensor network, this problem is particularly challenging as data routing strategies also affect the network lifetime performance. We present an approximation algorithm that can guarantee (1- )-optimal network lifetime performance with any desired error bound > 0. The key step is to divide the continuous search space into a finite number of subareas and represent each subarea with a "fictitious cost point" (FCP). We prove that the largest network lifetime achieved by one of these FCPs is (1- )-optimal. This approximation algorithm offers a significant reduction in complexity when compared to a state-of-the-art algorithm, and represents the best known result to this problem. 3. Mobile base station The benefits of using a mobile base station to prolong sensor network lifetime have been well recognized. However, due to the complexity of the problem (time-dependent network topology and traffic routing), theoretical performance limits and provably optimal algorithms remain difficult to develop. Our main result hinges upon a novel transformation of the joint base station movement and flow routing problem from the time domain to the space domain. Based on this transformation, we first show that if the base station is allowed to be present only on a set of pre-defined points, then we can find the optimal sojourn time for the base station on each of these points so that the overall network lifetime is maximized. Based on this finding, we show that when the location of the base station is un-constrained (i.e., can move to any point in the two-dimensional plane), we can develop an approximation algorithm for the joint mobile base station and flow routing problem such that the network lifetime is guaranteed to be at least (1- ) of the maximum network lifetime, where can be made arbitrarily small. This is the first theoretical result with performance guarantee on this problem. 4. Spectrum sharing in CR networks Cognitive radio is a revolution in radio technology that promises unprecedented flexibility in radio communications and is viewed as an enabling technology for dynamic spectrum access. We consider a cross-layer design of scheduling and routing with the objective of minimizing the required network-wide radio spectrum usage to support a set of user sessions. Here, scheduling considers how to use a pool of unequal size frequency bands for concurrent transmissions and routing considers how to transmit data for each user session. We develop a near-optimal algorithm based on a sequential fixing (SF) technique, where the determination of scheduling variables is performed iteratively through a sequence of linear programs (LPs). Upon completing the fixing of these scheduling variables, the value of the other variables in the optimization problem can be obtained by solving an LP. 5. Power control in CR networks We further consider the case of variable transmission power in CR networks. Now, our objective is minimizing the total required bandwidth footprint product (BFP) to support a set of user sessions. As a basis, we first develop an interference model for scheduling when power control is performed at each node. This model extends existing so-called protocol models for wireless networks where transmission power is deterministic. As a result, this model can be used for a broad range of problems where power control is part of the optimization space. An efficient solution procedure based on the branch-and-bound framework and convex hull relaxations is proposed to provide (1- )-optimal solutions. This is the first theoretical result on this important problem. ; Ph. D.

A wireless ad hoc network is composed of a decentralized set of mobile and self-organized hosts. Such a network does not rely on any infrastructure, and is thus completely autonomous and dynamic. Based on these concepts, any set of objects equipped with appropriate communication interfaces may spontaneously form such a network. As wireless communications are used, only closest hosts may directly communicate with each other. Long distance communications must be done through a multi-hopping mechanism: this simply means that intermediate objects have to forward the packets until the destination is reached. Wireless sensor networks are similar to ad hoc networks, as they are also decentralized and autonomous. A sensor is a small device with monitoring capabilities, allowing it to gather information on its environment. For instance, typical use case of sensor networks may be the monitoring of military areas (movements detection) or forests (heat detection). Among the common problems studied in these networks is broadcasting. In such communication, a message is sent from a given host to all the other ones in the network. Applications of this process are numerous: route discovery, synchronization\ldots{} As mobile objects rely on a battery, it is mandatory for the broadcast protocol to be energy efficient. This is generally done by reducing the quantity of needed relaying nodes, or by limiting the transmission power at each host. Of course, all these optimizations must preserve the reliability of the protocol. The goal of my work was to study broadcasting in ad hoc and sensor networks, in order to highlight the characteristics and the flaws of existing mechanisms, and to propose new efficient protocols. In all our proposals, we always tried to provide realistic solutions: a lot of previous studies was based on centralized mechanisms, where a global knowledge was needed to perform the broadcasting process. We focused on reliable and localized solutions, using only close information on the neighborhood of each node. This kind of solution is also more scalable, as the quantity of needed information does not grow with the size of the network. Some of our studies, especially in \cite{2005-medhoc}, show that these solutions may be as efficient as centralized ones. As power adjustment is a a mechanism of prime importance for energy preservation, we proposed in \cite{2006-tpds, 2004-medhoc, 2004-icc} an original broadcasting method based on the concept of optimal communication range. The latter is theoretically computed thanks to the considered energy model, and is the best compromise between the spent energy at each node and the quantity of relays. We thus proposed two different protocols based on this concept, each of them being specifically targeted either at ad hoc (TR-LBOP) or sensor networks (TR-DS). To further reduce energy savings, we studied a well-known centralized and very efficient protocol named BIP. Its efficiency is due to its consideration of the coverage obtained thanks to a single omnidirectional transmission, instead of considering all links separately. We proposed in \cite{2007-winet, 2005-iscc} a localized solution based on BIP, in order to incrementally construct a broadcasting structure. We experimentally showed that results are very close to those provided by BIP, especially in highest densities, while only local information is needed at each node. We finally considered the removal of a strong hypothesis, broadly spread in the ad hoc and sensor networks community, referred to as the unit disk graph. The latter defines the communication area of each device to be a perfect circle. In \cite{2006-msn}, we replaced this hypothesis by a more realistic one in order to study a well-known broadcasting mechanism, the multipoint relay protocol (MPR). We showed that MPR does not provide anymore sufficient performance in such a realistic environnement. We also proposed efficient modifications in order to get back efficient results. ; Un réseau ad hoc sans fil est composé d'un ensemble décentralisé d'objets mobiles et auto-organisés. Un tel réseau ne repose sur aucune infrastructure, et est donc complètement autonome et dynamique. Selon ces hypothèses, tout ensemble d'objets équipés d'interfaces de communication adéquates peut spontanément former un tel réseau. Puisque des communications sans fil sont utilisées, seuls les objets suffisamment proches les uns des autres peuvent communiquer ensemble. Les communications de longue portée doivent donc être effectuées via un mécanisme multi-sauts : cela veut simplement dire que les objets intermédiaires doivent faire suivre les messages jusqu'au destinataire. Les réseaux de capteurs sont similaires aux réseaux ad hoc, car ils sont également décentralisés et autonomes. Un capteur est un petit appareil capable de surveiller son environnement. Des cas typiques d'utilisation peuvent être la surveillance de zones militaires (détection de mouvements) ou de forêts (détection d'incendie). Parmi les problèmes communs à ces deux types de réseaux se trouve la diffusion. Dans une telle communication, un message est envoyé depuis un objet donné vers tous les autres du réseau. Les applications de ce processus sont nombreuses : découverte de routes, synchronisation. Comme les objets mobiles utilisent une batterie, il est nécessaire que la diffusion soit la plus économe possible d'un point de vue énergétique. Cela est généralement obtenu en réduisant la quantité de relais nécessaires, ou en limitant la puissance d'émission à chaque relais. Le but de mon travail était d'étudier la diffusion dans les réseaux ad hoc et de capteurs, afin de mettre en lumière les caractéristiques et les défauts des mécanismes existants, puis d'en proposer de nouveaux, plus efficaces. Dans tous ces travaux, nous avons toujours voulu rester dans le domaine des solutions 'réalistes' : beaucoup des précédentes études utilisaient en effet des mécanismes centralisés, où une connaissance globale du réseau est nécessaire pour effectuer la diffusion. Nous nous sommes concentrés sur des solutions fiables et localisés, c'est-à-dire n'utilisant que des informations sur le voisinage de chaque noeud. Ce type de mécanisme permet également un passage à l'échelle simplifié, car la quantité d'informations nécessaire ne varie pas avec la taille du réseau. Nos études montrent de plus que ces solutions peuvent être aussi efficaces que les méthodes centralisées. Puisque l'ajustement de portée est un mécanisme très important dans la conservation de l'énergie, nous avons proposé une méthode de diffusion originale, basée sur le concept de portée optimale de communication. Cette dernière est calculée de manière théorique grâce au modèle énergétique considéré, et représente le meilleur compromis entre l'énergie dépensée à chaque noeud et le nombre de relais nécessaires. Nous avons ainsi proposé deux protocoles différents basés sur ce concept, chacun étant plus spécifiquement adapté soit aux réseaux ad hoc (TR-LBOP), soit aux réseaux de capteurs (TR-DS). Afin de réduire encore plus la consommation énergétique, nous avons étudié le fameux protocole centralisé nommé BIP. Son efficacité est due au fait qu'il considère la couverture obtenue par une seule émission omnidirectionnelle, au lieu de considérer chaque lien séparément. Nous avons proposé une solution localisée basée sur BIP, afin de construire incrémentalement une structure de diffusion. Nous avons montré de manière expérimentale que les résultats ainsi obtenus sont très proches de ceux fournis par BIP, notamment dans les réseaux de forte densité, tout en n'utilisant que des informations locales à chaque noeud. Nous avons finalement considéré la suppression d'une hypothèse forte, largement répandue dans la communauté des réseaux ad hoc et de capteurs : l'utilisation d'un graphe du disque unitaire. Ce dernier définit la zone de communication d'un noeud comme étant un cercle parfait. Nous avons remplacé cette hypothèse par une autre plus réaliste afin d'en étudier les conséquences sur un protocole connu, le protocole de diffusion par relais multipoints (MPR). Nous avons montré que ce dernier ne fournit plus de résultats suffisants dans un tel environnement. Nous avons également proposé quelques modifications afin d'obtenir à nouveau de bons résultats.

Раздел "Международные экономические отношения" ; Внешняя политика КНР направлена на повышение роли Китая в международных вопросах и создание благоприятных условий для развития экономики. Китай неизменно претворяет в жизнь концепцию Дэн Сяопина, придерживается независимой и самостоятельной внешней политики, выступает в защиту территориальной целостности страны и суверенитета. Руководство КНР подчеркивает, что в международной политике Китай направляет усилия на обеспечение мира, не вступает ни в какие союзы и блоки, добивается добрососедских отношений с соседними странами. Между Республикой Беларусь и Китайской Народной Республикой достигнут высокий уровень сотрудничества. КНР является основным политическим и торгово-экономическим партнером Беларуси в Азии. Решающее значение для становления и развития двустороннего политического сотрудничества между Республикой Беларусь и Китайской Народной Республикой сыграло совпадение позиций по широкому кругу международных вопросов и поддержка друг друга в международных организациях. Создана значительная договорно-правовая база двусторонних отношений, охватывающая широкий круг вопросов сотрудничества между Республикой Беларусь и Китайской Народной Республикой. Подписанные договоры, программы и соглашения стали основой для становления, развития и укрепления связей Республики Беларусь и Китайской Народной Республики и обеспечили их стабильное развитие на долгосрочную перспективу. Закрепление в различных документах получило торгово-экономическое, научно-техническое, военное сотрудничество, сотрудничество в сфере образования, культуры. Китай действительно развивается стремительным темпом, что подтверждается различными показателями роста экономики. Характеризуя сложившуюся экономическую ситуацию в Китае, можно выделить следующие моменты: высокий рост инвестиций и экспорта; изменение структуры потребления в сторону строительства жилья, рынка автомобилей, потреблению средств связи; структурные изменения в экономике, связанные с привлечением новейших технологий и улучшение уровня жизни населения. Экономический подъем в Китае из года в год создает реальные предпосылки для успешной работы белорусских субъектов хозяйствования в КНР. Однако сегодня белорусский экспорт практически не заметен на этом перспективном и платежеспособном рынке. Для экспортоориентированной экономики Беларуси подобное состояние дел в торговле с ведущей страной Азии непозволительно. Более того, это происходит на фоне впечатляющих темпов развития Китая. В связи с этим, представляется целесообразным учесть в стратегии сотрудничества с КНР следующие основные моменты: 1) Развитие инфраструктуры торгово-экономических связей: задействования банков и страховых компаний двух стран для совершенствования расчетно-платежных отношений, кредитования поставок сложной машинотехнической продукции и оборудования с длительным циклом изготовления, финансирования инвестиционных проектов; совершенствование структуры транспортных перевозок, внедрение прогрессивных форм таможенного и санитарного контроля; развитие электронной торговли, а также прикладных информационных технологий. 2) Участие Беларуси в программах хозяйственного подъема западных провинций КНР. 3) Развитие прямой торговли с Китаем, без участия посредников, на основе расширения совместной торговой инфраструктуры — выставок, представительств, создания торговых и сервисных сетей. 4) Беларусь и Китай находятся на большом удалении друг от друга, поэтому необходимо развитие электронной торговли. 5) Состояние белорусско-китайской торговли показывает, что необходимо коренное изменение представлений белорусских экспортеров о Китае, как стране производящей высокотехническую продукцию. 6) По-прежнему концентрируя основные усилия на привлечении иностранного капитала, в Китае придают все большее значение инвестированию за рубеж. Правительство разработало специальную стратегию выхода на внешние рынки китайских фирм и предприятий. 7) Для китайских компаний также существуют немалые ниши для укрепления своих позиций на белорусском рынке. В первую очередь, это поставки недорогого и не уступающего западным аналогам оборудования для технической модернизации отечественных производителей, а также бытовой техники и товаров народного потребления в части, дополняющей ассортимент, производимый в Беларуси. В республике разработана стратегическая Программа активизации торгово-экономического сотрудничества с КНР на 2004—2008 гг. В программе отражены мероприятия по увеличению объемов экспорта белорусских предприятий в КНР, развитию товаропроводящей сети, выставочно-ярмарочной деятельности, созданию совместных предприятий (производств) на территории КНР, привлечению китайских инвестиций и финансовой помощи, дальнейшему развитию регионального сотрудничества с провинциями Китая. Реализация Программы позволит выполнить поставленные задачи по увеличению товарооборота между Беларусью и Китаем. = The foreign policy of the People's Republic of China is directed at raising China's role in the international life and creation of favourable conditions for its economic development. China steadily realizes the concept of Deng Xiaoping, adhering to the independent foreign policy policy, advocating territorial integrity and sovereignty. China's leadership emphasizes that in its international politics China supports peace, stays outside all unions and blocs and seeks good neighbourly relations with the bordering countries. The Republic of Belarus and the People's Republic of China can boast a high level of cooperation. China is the main political, trade and economic partner of Belarus in Asia. The decisive role for the formation and evolution of bilateral political cooperation between the Republic of Belarus and the People's Republic of China was played by the agreement in their opinions on a wide range of international issues and mutual support in the international organizations. The countries have established a significant legal treaty base for the bilateral relations involving different aspects of cooperation. The existing treaties, programmes and agreements underlie the formation, development and strengthening of ties between the Republic of Belarus and the People's Republic of China, thus providing their stable development in the long-term. Trade and economic, scientific and engineering, military, educational, cultural cooperation was fixed in various documents. China is indeed developing rapidly and showing various high indeces of economic growth. While characterizing the current economic situation in China, one can point out high investment and export growth, the shift of consumption pattern towards house-building, automobile and communications markets, and structural changes in the economy related to the latest technologies and the growth of standards of living. The economic boom in China from year to year creates real prerequisites for the successful work of Belarusian economic subjects in China. However, Belarusian export is currently almost insignificant on this promising and profitable market. The author states that it is unfitting for Belarus with its export oriented economy to have the existing level of cooperation with this leading Asian state. Moreover, it is happening against the background of impressing economic growth rates in China. In this connection, the author considers it advisable to take into account the following basic aspects when realizing the strategy of cooperation with China: 1) the development of infrastructure of trade and economic relations: involvement of banks and insurance companies of the two countries to improve the relations in the payments sphere, the crediting of deliveries of complex machinery and equipment with a long production cycle, financing of investment projects, the structure of transportation, introduction of new forms of customs and sanitary control, development of e-trade and applied information technologies; 2) participation of Belarus in the programmes of economic upswing of the China western provinces; 3) development of direct trade with China without any mediators on the basis of expansion of joint trade infrastructure: exhibitions, offices, trade and service networks; 4) development of e-trade because of long distance between two states; 5) radical change of awareness of Belarusian exporters about China as a country manufacturing high-tech produce; 6) while focusing its main efforts on attracting foreign capital, China gives ever greater importance to the investment expansion. The government elaborated a special strategy of foreign market entry for the Chinese companies and manufacturers; 7) Chinese companies also enjoy ample opportunities for strengthening their positions on the Belarusian market. Primarily, this is connected with supplying equipment to modernize Belarusian industry, competitive both in prices, which are reasonable, ad quality. Domestic appliances and consumer goods in addition to those produced in Belarus are also sold. The Belarusian strategic Programme of Intensification of Trade and Economic Cooperation with the People's Republic of China in 2004—2008 contains actions to increase the volume of export of Belarusian enterprises to China, to develop commodity distrubution network, exhibitions and fairs, to create of joint ventures on China's territory, to attract Chinese investments and financial aid, and to develop further regional cooperation with Chinese provinces. The Programme implementation will lead to the realization of the tasks on turnover growth between Belarus and China.