Suchergebnisse

Soluble salts are an important pollutant and the main decay agent of stone in the built environment. While their end erosive effects are well-established, the evolution in time of those erosive effects has been much less studied. This paper presents multivariate analyses of results from salt weathering cycles of three limestone types. ; The experimental data considered in this publication discussed were obtained in the context of the Project PORENET (POCTI/CTA/44940/2002) funded by the FCT—Fundação para a Ciência e Tecnologia (Portugal). The software and informatic equipment used in the preparation of this publication were also supported from funding of the FCT to the Centro de Investigação Geológica, Ordenamento e Valorização de Recursos of the School of Sciences of the University of Minho. ; The Lab2PT, Landscape, Heritage, and Territory Laboratory(UID/ECI/04028/2013) of the University of Minho and the CERENA—Centro de Recursos Naturais e Ambiente (UID/ECI/04028/2013) of the Instituto Superior Técnico, University of Lisbon are supported by the FCT—Fundação para a Ciência e Tecnologia (Portugal), with Portuguese funds and funds from the European Union (FEDER, Programa Operacional Factores de Competitividade—COMPETE 2020—Programa Operacional Competitividade e Internacionalização, POCI, POCI-01-0145-FEDER-007528). Acknowledgments also to Eng. Teresa Luís, Eng. Sónia Pereira, and Enterprise Mármores Galrão for the rock blocks. ...

An extended version of Principal Components Analysis (PCA) of monument stone decay phenomena occurring at "Basilica da Estrela" church, Lisbon, Portugal, is now presented. The PCA rationale and general methodological procedure is presented, as a first step of a stepwise approach to the eigenvector methods of data analysis. PCA, as others "Eigenvector Methods", seeks to reveal the underlying structure that might exist within a set of multivariate observations. Temperature, pH, electrical conductivity and main ionic species were measured on several seepage samples over three years inside the monument. PCA results are discussed in the perspective of a nondestructive tool. ; The authors gratefully acknowledge the support of the CERENA strategic project FCT-UID/ECI/04028/2013) and the LAMPIST of the Instituto Superior Técnico, University of Lisbon, as well as the Lab2PT, Landscape, Heritage and Territory Laboratory (UID/ECI/04028/2013) of the University of Minho supported by the FCT—Fundação para a Ciência e Tecnologia (Portugal), with Portuguese funds and funds from the European Union (FEDER, Programa Operacional Factores de Competitividade—COMPETE 2020—Programa Operacional Competitividade e Internacionalização, POCI, POCI-01-0145-FEDER-007528). ...

Here are discussed results of salt weathering laboratory tests on specimens of three limestones, two grainstones (designated as Semi-rijo and Moca Creme) and a travertine, considering parameters related to an initial ma ss in creasing phase and to mass differences between cycles in the mass decreasing phase. Results show a good ordinal correlation between final mass loss and maximum difference between cycles that differentiates the considered rock types. ; The Lab2PT, Landscape, Heritage and Territory Laboratory (UID/ECI/04028/2013) of the University of Minho and the CERENA - Centro de Recursos Naturais e Ambiente (UID/ECI/04028/2013) of the Instituto Superior Técnico, University of Lisbon are supported by the FCT - Fundação para a Ciência e Tecnologia (Portugal), with Portuguese funds and funds from the European Union (FEDER, Programa Operacional Factores de Competitividade – COMPETE 2020 – Programa Operacional Competitividade e Internacionalização, POCI, POCI-01-0145-FEDER-007528). The experimental data here discussed were obtained in the context of the Project PORENET (POCTI/CTA/44940/2002) also funded by the FCT. Acknowledgments also to Eng. Teresa Luís, Eng. Sónia Pereira, and Enterprise Mármores Galrão for the rock blocks ...

It is presented an overview of observations of features related to water-stone interactions in contemporary works of the built environment at several Portuguese locations, aiming to assess their relative importance and discuss their relation to engineering and architectural options. ; The Fundação para a Ciência e Tecnologia supports the Lab2PT, Landscape, Heritage and Territory Laboratory (UID/ECI/04028/2013, funds from Portuguese Republic and European Union, FEDER, Programa Operacional Factores de Competitividade – COMPETE 2020 – Programa Operacional Competitividade e Internacionalização, POCI, POCI-01-0145-FEDER-007528) and the CERENA - Centro de Recursos Naturais e Ambiente (UID/ECI/04028/2013, Portuguese funds). ...

The Iberian peninsula is a peripheral region of Europe in close proximity to Africa. Its inhabitants have an overall mtDNA genetic landscape typical of European background, although with signs of some African influence, whose features we deemed to disclose by analyzing available mtDNA HVRI distributions and new data. We analyzed 1,045 sequences. The most relevant results are the following: (1) North African sequences (haplogroup U6) present an overall frequency of 2.39%, and sub-Saharan sequences reach 3.83%, values that are, in both cases, much higher than those generally observed in Europe; and (2) there is a substantial geographic heterogeneity in the distribution of these lineages (haplogroup L being the most frequent in the south, whereas haplogroup U6 is generally more common in the north). The analysis of the observed diversity within each haplogroup strongly suggests that both were recently introduced (in historical times). Although for haplogroup U6 the documented event that is demographically compatible is the Islamic period (beginning of the 8th century to the end of the 15th century), for haplogroup L the most probable origin is the modern slave trade (mid 15th century to the end of the 18th century). However, the observed geographic structuring for one of the haplogroups does not fit the expected distribution provided by simplistic historical considerations. In fact, although for haplogroup L the north-south increasing frequency is corroborated by historical data, the opposite trend, observed for haplogroup U6, is more difficult to reconcile with the magnitude and time span of the Islamic political and cultural influence, which lasted longer and was more intense in the south. To clarify this conundrum, we need not only a substantial increase in the amount of mtDNA data (particularly for North Africa) but also new historical data and interpretations. ; This work was partially supported by a research grant to LP (SFRH/BPD/7121/2001) from Fundacao para a Ciencia e a Tecnologia and IPATIMUP by Programa Operacional Ciencia, Tecnologia e Inovacao (POCTI), Quadro Comunitario de Apoio III.

Context. The bright star π Men was chosen as the first target for a radial velocity follow-up to test the performance of ESPRESSO, the new high-resolution spectrograph at the European Southern Observatory's Very Large Telescope. The star hosts a multi-planet system (a transiting 4 M· planet at ∼0.07 au and a sub-stellar companion on a ∼2100-day eccentric orbit), which is particularly suitable for a precise multi-technique characterization. Aims. With the new ESPRESSO observations, which cover a time span of 200 days, we aim to improve the precision and accuracy of the planet parameters and search for additional low-mass companions. We also take advantage of the new photometric transits of π Men c observed by TESS over a time span that overlaps with that of the ESPRESSO follow-up campaign. Methods. We analysed the enlarged spectroscopic and photometric datasets and compared the results to those in the literature. We further characterized the system by means of absolute astrometry with HIPPARCOS and Gaia. We used the high-resolution spectra of ESPRESSO for an independent determination of the stellar fundamental parameters. Results. We present a precise characterization of the planetary system around π Men. The ESPRESSO radial velocities alone (37 nightly binned data with typical uncertainty of 10 cm s-1) allow for a precise retrieval of the Doppler signal induced by π Men c. The residuals show a root mean square of 1.2 m s-1, which is half that of the HARPS data; based on the residuals, we put limits on the presence of additional low-mass planets (e.g. we can exclude companions with a minimum mass less than ∼2 M· within the orbit of π Men c). We improve the ephemeris of π Men c using 18 additional TESS transits, and, in combination with the astrometric measurements, we determine the inclination of the orbital plane of π Men b with high precision (ib =45.8-1.1+1.4 deg). This leads to the precise measurement of its absolute mass mb =14.1-0.4+0.5 MJup, indicating that π Men b can be classified as a brown dwarf. Conclusions. The π Men system represents a nice example of the extreme precision radial velocities that can be obtained with ESPRESSO for bright targets. Our determination of the 3D architecture of the π Men planetary system and the high relative misalignment of the planetary orbital planes put constraints on and challenge the theories of the formation and dynamical evolution of planetary systems. The accurate measurement of the mass of π Men b contributes to make the brown dwarf desert a bit greener. ; With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)