Effective transport barriers in nontwist systems

In fluids and plasmas with zonal flow reversed shear, a peculiar kind of transport barrier appears in the shearless region, one that is associated with a proper route of transition to chaos. These barriers have been identified in symplectic nontwist maps that model such zonal flows. We use the so-called standard nontwist map, a paradigmatic example of nontwist systems, to analyze the parameter dependence of the transport through a broken shearless barrier. On varying a proper control parameter, we identify the onset of structures with high stickiness that give rise to an effective barrier near the broken shearless curve. Moreover, we show how these stickiness structures, and the concomitant transport reduction in the shearless region, are determined by a homoclinic tangle of the remaining dominant twin island chains. We use the finite-time rotation number, a recently proposed diagnostic, to identify transport barriers that separate different regions of stickiness. The identified barriers are comparable to those obtained by using finite-time Lyapunov exponents.FAPESPCNPqCAPESMCT/CNEN (Rede Nacional de Fusao)Fundacao AraucariaUS Department of Energy DE-FG05-80ET-53088Physic

The WFCAM Multi-wavelength Variable Star Catalog

Stellar variability in the near-infrared (NIR) remains largely unexplored. The exploitation of public science archives with data-mining methods offers a perspective for the time-domain exploration of the NIR sky. We perform a comprehensive search for stellar variability using the optical-NIR multi-band photometric data in the public Calibration Database of the WFCAM Science Archive (WSA), with the aim of contributing to the general census of variable stars, and to extend the current scarce inventory of accurate NIR light curves for a number of variable star classes. We introduce new variability indices designed for multi-band data with correlated sampling, and apply them for pre-selecting variable star candidates, i.e., light curves that are dominated by correlated variations, from noise-dominated ones. Pre-selection criteria are established by robust numerical tests for evaluating the response of variability indices to colored noise characteristic to the data. We find 275 periodic variable stars and an additional 44 objects with suspected variability with uncertain periods or apparently aperiodic variation. Only 44 of these objects had been previously known, including 11 RR~Lyrae stars in the outskirts of the globular cluster M3 (NGC~5272). We provide a preliminary classification of the new variable stars that have well-measured light curves, but the variability types of a large number of objects remain ambiguous. We classify most of the new variables as contact binary stars, but we also find several pulsating stars, among which 34 are probably new field RR~Lyrae and 3 are likely Cepheids. We also identify 32 highly reddened variable objects close to previously known dark nebulae, suggesting that these are embedded young stellar objects. We publish our results and all light-curve data as the WFCAM Variable Star Catalog.Comment: 21 pages, 11 figure

Sobre o valor relevante das demonstrações financeiras separadas

A promulgação do Regulamento n.º 1606/2002 obrigou a que as entidades com títulos admitidos à cotação em Bolsa, na União Europeia, preparassem as suas demonstrações financeiras consolidadas de acordo com as International Financial Reporting Standards (IFRS) endossadas, mas concede a cada Estado Membro (EM) a escolha sobre o normativo a utilizar na preparação das demonstrações financeiras separadas. Dada a diversidade pelo facto de os Estados Membros poderem obrigar, permitir, ou proibir a aplicação das IFRS na preparação das demonstrações financeiras separadas das entidades que consolidam, este estudo tem como objetivo perceber se as DF separadas são relevantes, e se essa relevância é condicionada pela proibição ou obrigação do uso das IFRS na sua preparação. Este estudo inclui informação de entidades com títulos admitidos à cotação em bolsa em 17 países da EU nos quais a utilização das IFRS é exigida numas jurisdições e proibida em outras. Os resultados sugerem que as demonstrações financeiras separadas são relevantes para explicar o valor de mercado de uma entidade, e que a proibição do uso das IFRS na preparação dessas DF separadas mitiga o valor relevante do seu capital próprio e dos resultados líquidos, ainda que apenas no caso do capital próprio essa atenuação seja estatisticamente significativa.info:eu-repo/semantics/publishedVersio

Active emigration from climate change-caused seawater intrusion into freshwater habitats

Ecological risk assessment associated with seawater intrusions has been supported on the determination of lethal/sublethal effects following standard protocols that force exposure neglecting the ability of mobile organisms to spatially avoid salinized environments. Thus, this work aimed at assessing active emigration from climate change-caused seawater intrusion into freshwater habitats. To specific objectives were delineated: first, to compute median 12-h avoidance conductivities (AC50,12h) for freshwater species, and second, to compare it with literature data (LC50,48 or 96h, EC50,6 or 21d) to assess the relevance of the inclusion of stressor-driven emigration into risk assessment frameworks. Four standard test species, representing a broad range of ecological niches - Daphnia magna, Heterocypris incongruens, Danio rerio and Xenopus laevis - were selected. The salt NaCl was used as a surrogate of natural seawater to create the saline gradient, which was established in a 7-compartment system. At each specific LC50, 48 or 96h, the proportion of avoiders were well above 50%, ranging from 71 to 94%. At each LC50, considering also avoiders, populations would decline by 85-97%. Furthermore, for D. magna and X. laevis it was noticed that at the lowest conductivities eliciting mortality, the avoidance already exceeded 50%. The results showed that the emigration from salinity-disturbed habitats exists and that can even be more sensitive than standard endpoints. Looking solely to standard endpoints involving forced exposure may greatly underestimate the risk of local population extinction, because habitat function can be severely disrupted, with subsequent stressor-driven emigration, before any adverse physiological effects at the organism level. Thus, the present study highlights the need to include non-forced exposure testing into ecological risk assessment, namely of salinity-menaced costal freshwaters.publishe

Social identity and attitudes toward HIV pre-exposure prophylaxis: a structural equation model

This study focuses on the role of social identity and prejudice as causal variables in public attitudes toward pre-exposure prophylaxis (PrEP) in a UK sample. In all, 222 participants participated in an experimental vignette study with a 2 × 2 × 2 design with between-participants factors of ethnicity, sexual orientation and gender, and completed measures of attitudes toward gay men, Black Africans, and PrEP. Kruskal–Wallis tests showed significant effects of gender on attitudes toward gay men and Black Africans; of ethnicity on attitudes toward gay men and PrEP; and of religion on attitudes toward gay men. A univariate analysis of variance (ANOVA) revealed more positive attitudes toward PrEP when it was presented as benefitting men (vs. women). Structural equation modeling showed that the relationship between the independent variables of gender, ethnicity, and religion and the dependent variable of attitudes toward PrEP was mediated by attitudes toward gay men and Black Africans. Individuals must perceive the principal beneficiaries of PrEP (i.e., gay men and Black Africans) positively to endorse PrEP for these groups, and sexism may reduce public acceptability of PrEP for women. Future research should use representative samples and alternative experimental manipulations, and include strength of social identification as an independent variable

Development of liquid xenon detectors for medical imaging

In the present paper, we report on our developments of liquid xenon detectors for medical imaging, positron emission tomography and single photon imaging, in particular. The results of the studies of several photon detectors (photomultiplier tubes and large area avalanche photodiode) suitable for detection of xenon scintillation are also briefly described.Comment: 13 pages, 5 figures, presented on the International Workshop on Techniques and Applications of Xenon Detectors (Xenon01), ICRR, Univ. of Tokyo, Kashiwa, Japan, December 3-4, 2001 (submitted to proceedings

Non-parametric comparison of histogrammed two-dimensional data distributions using the Energy Test

When monitoring complex experiments, comparison is often made between regularly acquired histograms of data and reference histograms which represent the ideal state of the equipment. With the larger HEP experiments now ramping up, there is a need for automation of this task since the volume of comparisons could overwhelm human operators. However, the two-dimensional histogram comparison tools available in ROOT have been noted in the past to exhibit shortcomings. We discuss a newer comparison test for two-dimensional histograms, based on the Energy Test of Aslan and Zech, which provides more conclusive discrimination between histograms of data coming from different distributions than methods provided in a recent ROOT release.The Science and Technology Facilities Council, U

Partition functions and elliptic genera from supergravity

We develop the spacetime aspects of the computation of partition functions for string/M-theory on AdS(3) xM. Subleading corrections to the semi-classical result are included systematically, laying the groundwork for comparison with CFT partition functions via the AdS(3)/CFT(2) correspondence. This leads to a better understanding of the "Farey tail" expansion of Dijkgraaf et. al. from the point of view of bulk physics. Besides clarifying various issues, we also extend the analysis to the N=2 setting with higher derivative effects included.Comment: 34 page