University of Siena

About: University of Siena is a education organization based out in Siena, Italy. It is known for research contribution in the topics: Population & Cancer. The organization has 12179 authors who have published 33334 publications receiving 1008287 citations. The organization is also known as: Università degli studi di Siena & Universita degli studi di Siena.

High resolution satellite imagery for tropical biodiversity studies: the devil is in the detail

Abstract: While high resolution satellite remote sensing has been hailed as a very useful source of data for biodiversity assessment and monitoring, applications have been more developed in temperate areas. The biodiverse tropics offer a challenge of an altogether different magnitude for hyperspatial and hyperspectral remote sensing. This paper examines issues related to hyperspatial and hyperspectral remotely sensed imagery, which constitutes one of the most potentially powerful yet underutilized sources of for tropical research on biodiversity. Hyperspatial data with their increased pixel resolution are possibly best suited at facilitating the accurate location of features such as tree canopies, but less suited to the identification of aspects such as species identity, particularly when spatial resolution becomes too fine and pixels are smaller than the size of the object (e.g., tree canopy) being identified. Hyperspectral data on the other hand, with their high spectral resolution, can be used to record information pertaining to a range of critical plant properties related to species identity, and can be very effective used for discriminating tree species in tropical forests, despite the greater complexity of such environments. There remains a glaring gap in the easy availability of hyperspectral and hyperspatial satellite data in the tropics due to reasons of cost, data coverage, and security restrictions. Stimulating discussion on the applications of this powerful, but underutilized tool by ecologists, is the first step in promoting a more extensive use of such data for ecological studies in tropical biodiversity rich areas.

Real Exchange Rate Dynamics in Transition Economies

Abstract: Real exchange appreciation has been a common feature in transition economies since the launching of stabilization and reform programs at the beginning of the 1990s. Previous literature has described this phenomenon as an equilibrium adjustment that followed a sharp undervaluation at the start of the reforms. This Paper argues that real appreciation had different sources over time and across countries. Building on a simple analytical framework, the Paper disentangles these differences and stresses the role of structural reforms and factor reallocation in determining the behavior of the real exchange rate. The empirical results show that the nature of the real appreciation was significantly different in the countries of the Former Soviet Union (FSU), except for the Baltic countries, and in Central and Eastern Europe. The role of structural change and transitional reallocation of resources across sectors diminishes through time, and stabilizes around the fifth or sixth year into the transition. The dynamics of the real exchange rate in several Central-Eastern European countries (CEE) in the process of accession to the European Union, can be now assimilated to that of previously acceding countries such as Spain, Portugal, and Greece, with the Harrod-Balassa-Samuelson effect playing a dominant role at later stages of transition. The Paper concludes by discussing the implications for exchange rate policy for transition economies and potential drawbacks of the Maastricht criteria once CEEs enter the European Union.

Magnetic classification of stony meteorites: 2. Non-ordinary chondrites

Abstract: A database of magnetic susceptibility (χ) measurements on different non-ordinary chondrites (C, E, R, and ungrouped) populations is presented and compared to our previous similar work on ordinary chondrites. It provides an exhaustive study of the amount of iron-nickel magnetic phases (essentially metal and magnetite) in these meteorites. In contrast with all the other classes, CM and CV show a wide range of magnetic mineral content, with a two orders of magnitude variation of ?. Whether this is due to primary parent body differences, metamorphism or alteration, remains unclear. C34 and C2 yield similar χ values to the ones shown by CK and CM, respectively. By order of increasing χ, the classes with well-grouped χ are: R << CO < CK ≈ CI < Kak < CR < E ≈ CH < CB. Based on magnetism, EH and EL classes have indistinguishable metal content. Outliers that we suggest may need to have their classifications reconsidered are Acfer 202 (CO), Elephant Moraine (EET) 96026 (C45), Meteorite Hills (MET) 01149, and Northwest Africa (NWA) 521 (CK), Asuka (A)-88198, LaPaz Icefield (LAP) 031156, and Sahara 98248 (R). ? values can also be used to define affinities of ungrouped chondrites, and propose pairing, particularly in the case of CM and CV meteorites.

Perinatal exposure to the estrogenic pollutant bisphenol A affects behavior in male and female rats.

Abstract: Bisphenol A (BPA) is an environmental estrogen with potentially aversive effects on public health. In rats, we studied the effects of perinatal exposure to BPA on nonsocial behaviors partly influenced by gonadal hormones. BPA was administered orally to one group of mother rats at a concentration within the range of human exposure from 10 days before mating until the weaning of the pups. In a second group, BPA was given at a higher dosage during a critical period for brain organization, i.e., from day 14 of gestation until day 6 after birth. The offspring of the treated mothers were tested in the holeboard and the elevated plus-maze at 85 days of age. Various aspects of nonsocial behavior were affected by BPA, differently in males and females, confirming that exposure to a weak environmental estrogen in the period of sexual differentiation of the brain can influence adult behavior. However, contrary to our expectation, a clear masculinization of females was not observed. In general, the factor analysis indicated that in treated males both the motivation to explore and anxiety are reduced, while in females, motor activity and motivation to explore are depressed. Because there were no substantial differences between the two modalities of BPA administration, we suggest that the prolonged treatment with the low dosage compensates for the higher dosage given during a shorter steroid-sensitive period. This may be a cause of concern for public health, given the greater incidence of prolonged exposure of humans to low concentrations released into the environment.

Left Atrial Deformation Analysis by Speckle Tracking Echocardiography for Prediction of Cardiovascular Outcomes

Abstract: The incremental value of left atrial (LA) deformation analysis by speckle tracking echocardiography compared with LA volume or LA ejection fraction as a cardiovascular risk marker has not been evaluated prospectively. We sought to compare LA function by speckle tracking echocardiography to other conventional LA parameters for prediction of adverse cardiovascular outcomes. This prospective study included 312 adults (mean age 71 ± 6 years, 56% men) in sinus rhythm who were followed for development of first atrial fibrillation, congestive heart failure, stroke, transient ischemic attack, myocardial infarction, coronary revascularization, and cardiovascular death. Global peak atrial longitudinal strain (PALS) by speckle tracking echocardiography was measured in all subjects by averaging all atrial segments. Left atrium was assessed with biplane LA volume, LA ejection fraction, 4-chamber LA area, and M-mode dimension. Of 312 subjects at baseline, 43 had 61 new events during a mean follow-up of 3.1 ± 1.4 years. All LA parameters, traditional parameters, and parameters derived by speckle tracking echocardiography were independently predictive of combined outcomes (p <0.0001 for all comparisons). Overall performance for prediction of cardiovascular events was greatest for global PALS (area under receiver operator characteristic curve: global PALS 0.83, indexed LA volume 0.71, LA ejection fraction 0.69, LA area 0.64, LA diameter 0.59). A graded association between degree of LA enlargement and risk of cardiovascular events was evident only for global PALS and indexed LA volume. In conclusion, global PALS is a strong and independent predictor of cardiovascular events and appears to be superior to conventional parameters of LA analysis.