Suchergebnisse

Several emerging exotic diseases are currently oscillating on the eastern borders of the European Union (EU) including the bovine pathogen Lumpy skin disease virus (LSDV). Given the recent transboundary spread of LSDV into the EU, assessing the probability of further expansion is an important part of EU surveillance and can inform policy regarding risk mitigation priorities. This qualitative assessment focuses on the probability of introduction and onward transmission of LSDV into the United Kingdom (UK) for the time period June 2017 to June 2018. Overall the probability of introduction was considered, at most, to be very low. The probability of onward transmission was considered highest for vector mediated routes either via contact of an infected vector with susceptible cattle or contact of a competent native vector with an infected cattle. Factors with high uncertainty were identified to emphasise their impact on the assessment conclusions and for future research requirements. Medium to high uncertainty surrounds the probability of introduction to the UK via several of the routes assessed, in particular, the species of vectors involved and the illegal/legal import of meat and milk products; all estimates made consequential to these probabilities are therefore underpinned by high uncertainty. Whilst the assessment was UK centric the knowledge gaps are relevant to the probability of introduction and spread of LSDV in any geographical region. The value of estimating uncertainty lies in the identification of research required to make conclusions more robust.

African swine fever (ASF) is currently spreading westwards throughout Europe and eastwards into China, with cases occurring in both wild boar and domestic pigs. A generic risk assessment framework is used to determine the probability of first infection with ASF virus (ASFV) at a fine spatial scale across European Union Member States. The framework aims to assist risk managers across Europe with their ASF surveillance and intervention activities. Performing the risk assessment at a fine spatial scale allows for hot-spot surveillance, which can aid risk managers by directing surveillance or intervention resources at those areas or pathways deemed most at risk, and hence enables prioritization of limited resources. We use 2018 cases of ASF to estimate prevalence of the disease in both wild boar and pig populations and compute the risk of initial infection for 2019 at a 100 km2 cell resolution via three potential pathways: legal trade in live pigs, natural movement of wild boar, and legal trade in pig meat products. We consider the number of pigs, boar and amount of pig meat entering our area of interest, the prevalence of the disease in the origin country, the probability of exposure of susceptible pigs or boar in the area of interest to introduced infected pigs, boar, or meat from an infected pig, and the probability of transmission to susceptible animals. We provide maps across Europe indicating regions at highest risk of initial infection. Results indicate that the risk of ASF in 2019 was predominantly focused on those regions which already had numerous cases in 2018 (Poland, Lithuania, Hungary, Romania, and Latvia). The riskiest pathway for ASFV transmission to pigs was the movement of wild boar for Eastern European countries and legal trade of pigs for Western European countries. New infections are more likely to occur in wild boar rather than pigs, for both the pig meat and wild boar movement pathways. Our results provide an opportunity to focus surveillance activities and thus increase our ability to detect ...

Sheep pox and goat pox (SPGP) virus and lumpy skin disease (LSD) virus belong to the genus Capripoxvirus and cause disease with economic impacts in sheep/goats and cattle respectively. In 2013/14, outbreaks of SPGP were reported in sheep in Greece and Bulgaria and LSD outbreaks were reported in cattle in Turkey, Egypt and some countries in the Middle East. Clinical signs for both diseases include pox lesions, papules and scabs on the skin which may contain virus. This, together with the fact that Great Britain (GB) currently imports cattle hides, sheep skins and wool from European Union (EU) countries without the requirement for treatment prior to export, raises concern that capripoxviruses could be introduced into GB. A qualitative assessment presented here concluded that the current risk of entry of SPGP virus into GB through the importation of one untreated sheep skin, hide or wool bale from an EU Member State (MS) with similar flock prevalence to that in sheep in Greece in 2013/14 is low. In terms of SPGP virus levels, those infected sheep skins/hides entering GB are more likely to be from infected animals with normal skin (i.e., not showing lesions) and hence carrying lower levels of virus than those from animals showing papules and scabs which contain very high virus levels and are easier to detect. The predicted risk of importation of LSD virus per cattle hide/skin is also low (assuming LSD were to emerge in an EU MS with similar herd prevalence to that reported for SPGP in Greece in 2013/14). The levels of LSD virus on an infected cow's hide, if imported, may be very low. It is recommended that the risks for entry of capripoxviruses are recalculated if outbreaks occur elsewhere within the EU.

Discarding by fisheries is perceived as contrary to responsible harvesting. Legislation seeking to end the practice is being introduced in many jurisdictions. But, discarded fish are food for a range of scavenging species so ending discarding may have ecological consequences. Here we investigate the sensitivity of ecological effects to discarding policies using an ecosystem model of the North Sea - a region where 30-40% of trawled fish catch is currently discarded. We show that landing the entire catch whilst fishing as usual has conservation penalties for seabirds, marine mammals and seabed fauna, and no benefit to fish stocks. However, combining landing obligations with changes in fishing practices to limit the capture of unwanted fish results in trophic cascades that can benefit birds, mammals and most fish stocks. Our results highlight the importance of considering the broader ecosystem consequences of fishery management policy, since species interactions may dissipate or negate intended benefits.

The reduction of riverine nutrients inputs is considered the means of choice to improve the eutrophication status of the southern North Sea. With the European Union's Water Framework Directive (WFD) reduction measures presently under debate, two questions arise: (1) What changes in eutrophication indicators can be expected? (2) How do the reductions by the individual member states contribute to these? We combine an element tracing method (TBNT) with a biogeochemical model to analyze the effects of WFD-compliant nitrogen reductions proposed by OSPAR's North Sea member states. We first analyze changes in selected OSPAR assessment parameters relative to a reference simulation. Second, we quantify the source-specific contributions to total nitrogen (TN) in different regions. An overall nitrogen load reduction of 14 % is achieved. However, the response shows significant spatial variations due to strong differences between the countries' load reductions. TN and dissolved inorganic nitrogen reductions up to 60 % and 35 % are simulated near the Bay of Seine (France) and in the German Bight, respectively. Along the Dutch coast, reductions are below 10 %, and no changes occur along the British coast. Reductions in chlorophyll-a are generally lower. The TBNT analysis for the German Exclusive Economic Zone shows a TN reduction in the coastal region comparable to the N reductions in the German rivers (~25 %). In the offshore region, TN is reduced by only 6 % due to the strong influence of riverine sources with only low reductions and non-riverine sources. Our analysis reveals that non-linear responses in the biogeochemistry cause a faster removal of N from rivers with strong reductions by benthic denitrification, which enhances indirectly the removal of N from less reduced sources. Consequently, reductions in remote sources in non-problem areas can have a relevant positive effect on problem areas. This demonstrates that the TBNT method is an ideal tool to put in practice the "source-oriented approach" advocated by OSPAR, and ...

1 Sufficiency -- 1.1 Introduction -- 1.2 Factorization criterion -- 1.3 Distribution of statistics conditional on a sufficient statistic -- 1.4 Joint sufficiency -- 1.5 Minimal sufficiency -- 2 Unbiased point estimators -- 2.1 Introduction -- 2.2 Rao-Blackwell theorem -- 2.3 The role of sufficient statistics -- 2.4 Completeness -- 2.5 Joint completeness -- 2.6 Sufficiency, completeness and independence -- 2.7 Minimum-variance bounds -- 2.8 Computation of a minimum-variance bound -- 2.9 Minimum attainable variance -- 2.10 Mean square error -- 2.11 Two parameters -- 3 Elementary decision theory and Bayesian methods -- 3.1 Comments on classical techniques -- 3.2 Loss functions -- 3.3 Decision theory -- 3.4 Bayes decisions -- 3.5 Using data -- 3.6 Computing posterior distributions -- 3.7 Conjugate distributions -- 3.8 Distribution of the next observation -- 3.9 More than one parameter -- 3.10 Decision functions -- 3.11 Bayes estimators -- 3.12 Admissibility -- 4 Methods of estimation -- 4.1 Introduction -- 4.2 Maximum likelihood estimation -- 4.3 Locating the maximum likelihood estimator -- 4.4 Estimation of a function of a parameter -- 4.5 Truncation and censoring -- 4.6 Estimation of several parameters -- 4.7 Approximation techniques -- 4.8 Large-sample properties -- 4.9 Method of least squares -- 4.10 Normal equations -- 4.11 Solution of the normal equations (non-singular case) -- 4.12 Use of matrices -- 4.13 Best unbiased linear estimation -- 4.14 Co variance matrix -- 4.15 Relaxation of assumptions -- 5 Hypothesis testing I -- 5.1 Introduction -- 5.2 Statistical hypothesis -- 5.3 Simple null hypothesis against simple alternative -- 5.4 Applications of the Neyman-Pearson theorem -- 5.5 Uniformly most powerful tests for a single parameter -- 5.6 Most powerful randomized tests -- 5.7 Hypothesis testing as a decision process -- 5.8 Minimax and Bayes tests -- 6 Hypothesis testing II -- 6.1 Two-sided tests for a single parameter -- 6.2 Neyman-Pearson theorem extension (nonrandomized version) -- 6.3 Regular exponential family of distributions -- 6.4 Uniformly most powerful unbiased test of ? = ?0 against ? ? ?0 -- 6.5 Nuisance parameters -- 6.6 Similar tests -- 6.7 Composite hypotheses-several parameters -- 6.8 Likelihood ratio tests -- 6.9 Bayes methods -- 6.10 Loss function for one-sided hypotheses -- 6.11 Testing ? = ?0 against ? ? ?0 -- 7 Interval estimation -- 7.1 One parameter, Bayesian confidence intervals -- 7.2 Two parameters, Bayesian confidence regions -- 7.3 Confidence intervals (classical) -- 7.4 Most selective limits -- 7.5 Relationship to best tests -- 7.6 Unbiased confidence intervals -- 7.7 Nuisance parameters -- 7.8 Discrete distributions -- 7.9 Relationship between classical and Bayesian intervals -- 7.10 Large-sample confidence intervals -- Appendix 1 Functions of random variables -- A 1.1 Introduction -- A 1.2 Transformations: discrete distributions -- A1.3 Continuous distributions -- A 1.4 The order statistics -- Appendix 2 The regular exponential family of distributions -- A2.1 Single parameter -- A2.2 Several parameters -- A2.3 The regular exponential family of bivariate distributions -- Further exercises -- Brief solutions to further exercises -- Further reading -- Author index.

Background: Diagnosis is key to control and prevention of livestock diseases. In areas of sub-Saharan Africa where private practitioners rarely replace Government veterinary services reduced in effectiveness by structural adjustment programmes, those who remain lack resources for diagnosis and might benefit from decision support. Methodology/Principal Findings: We evaluated whether a low-cost diagnostic decision support tool would lead to changes in clinical diagnostic practice by fifteen veterinary and animal health officers undertaking primary animal healthcare in Uganda. The eight diseases covered by the tool included 98% of all bovine diagnoses made before or after its introduction. It may therefore inform proportional morbidity in the area; breed, age and geographic location effects were consistent with current epidemiological understanding. Trypanosomosis, theileriosis, anaplasmosis, and parasitic gastroenteritis were the most common conditions among 713 bovine clinical cases diagnosed prior to introduction of the tool. Thereafter, in 747 bovine clinical cases estimated proportional morbidity of fasciolosis doubled, while theileriosis and parasitic gastroenteritis were diagnosed less commonly and the average number of clinical signs increased from 3.5 to 4.9 per case, with 28% of cases reporting six or more signs compared to 3% beforehand. Anaemia/pallor, weakness and staring coat contributed most to this increase, approximately doubling in number and were recorded in over half of all cases. Finally, although lack of a gold standard hindered objective assessment of whether the tool improved the reliability of diagnosis, informative concordance and misclassification matrices yielded useful insights into its role in the diagnostic process. Conclusions/Significance: The diagnostic decision support tool covered the majority of diagnoses made before or after its introduction, leading to a significant increase in the number of clinical signs recorded, suggesting this as a key beneficial consequence of its use. It may also inform approximate proportional morbidity and represent a useful epidemiological tool in poorly resourced areas.

Care should be taken in the writing of papers in mathematical statistics for two reasons. First this enhances a paper's chances to be accepted for publication in a top journal. Second the contributions of a paper will reach a wider audience if the main ideas are easily accessible. This paper gives suggestions for improvement in two directions: presentation of mathematics and organization of papers.

Statistics is the science that focuses on drawing conclusions from data, by modeling and analyzing the data using probabilistic models. In An Introduction to Mathematical Statistics the authors describe key concepts from statistics and give a mathematical basis for important statistical methods. Much attention is paid to the sound application of those methods to data. The three main topics in statistics are estimators, tests, and confidence regions. The authors illustrate these in many examples, with a separate chapter on regression models, including linear regression and analysis of variance. They also discuss the optimality of estimators and tests, as well as the selection of the best-fitting model. Each chapter ends with a case study in which the described statistical methods are applied. This book assumes a basic knowledge of probability theory, calculus, and linear algebra.--

AbstractAsymptotic representations are found for the large deviation probabilities that the nα‐th order statistic exceeds δ, where δ>α. The probabilities are first expressed in terms of the empirical distribution function, and then the 1960 theorem of Bahadur and Ranga Rao is applied. The result is then shown to be more precise than a logarithmic statement in a 1969 paper of Sievers dealing with the asymptotic relative efficiency of the sample median test.