174 research outputs found
A finite volume scheme for nonlinear degenerate parabolic equations
We propose a second order finite volume scheme for nonlinear degenerate
parabolic equations. For some of these models (porous media equation,
drift-diffusion system for semiconductors, ...) it has been proved that the
transient solution converges to a steady-state when time goes to infinity. The
present scheme preserves steady-states and provides a satisfying long-time
behavior. Moreover, it remains valid and second-order accurate in space even in
the degenerate case. After describing the numerical scheme, we present several
numerical results which confirm the high-order accuracy in various regime
degenerate and non degenerate cases and underline the efficiency to preserve
the large-time asymptotic
The psychological effects of terrorism are moderated by cultural worldviews
Terrorism cannot be easily studied experimentally for obvious reasons. We report the results of a laboratory study (N = 149) testing the effect of cultural worldviews on feelings of threat and hostility toward Muslims in France that include in the design the deadly terrorist attack of January 7th 2015 in Paris as a naturally occurring independent variable. The results replicate past research by showing that in a natural context, people felt more threatened and more hostile toward Muslims after the terrorist attack than before. However, the reverse occurred in an experimental condition that made the French cultural worldview of colorblind equality salient: People felt less threatened and less hostile after the terrorist attack than before. These results provide, for the first time in the context of a real terrorist attack, support for Terror Management Theory's proposal that cultural worldviews are an effective buffer against terror
Uncertainty quantification for kinetic models in socio-economic and life sciences
Kinetic equations play a major rule in modeling large systems of interacting
particles. Recently the legacy of classical kinetic theory found novel
applications in socio-economic and life sciences, where processes characterized
by large groups of agents exhibit spontaneous emergence of social structures.
Well-known examples are the formation of clusters in opinion dynamics, the
appearance of inequalities in wealth distributions, flocking and milling
behaviors in swarming models, synchronization phenomena in biological systems
and lane formation in pedestrian traffic. The construction of kinetic models
describing the above processes, however, has to face the difficulty of the lack
of fundamental principles since physical forces are replaced by empirical
social forces. These empirical forces are typically constructed with the aim to
reproduce qualitatively the observed system behaviors, like the emergence of
social structures, and are at best known in terms of statistical information of
the modeling parameters. For this reason the presence of random inputs
characterizing the parameters uncertainty should be considered as an essential
feature in the modeling process. In this survey we introduce several examples
of such kinetic models, that are mathematically described by nonlinear Vlasov
and Fokker--Planck equations, and present different numerical approaches for
uncertainty quantification which preserve the main features of the kinetic
solution.Comment: To appear in "Uncertainty Quantification for Hyperbolic and Kinetic
Equations
Sexualisation's four faces: sexualisation and gender stereotyping in the Bailey Review
This paper explores the considerations of sexualisation and gender stereotyping in the recent UK government report Letting Children be Children. This report, the Bailey Review, claimed to represent the views of parents. However, closer reading reveals that, while the parents who were consulted were concerned about both the sexualisation and the gender stereotyping of products aimed at children, the Bailey Review focuses only on the former and dismisses the latter. âSexualisationâ has four faces in the Bailey Review: it is treated as a process that increases (1) the visibility of sexual content in the public domain, (2) misogyny, (3) the sexuality of children, and (4) the mainstream position of âdeviantâ sexual behaviours and lifestyles. Through this construction of âsexualisationâ, gendered relations of power are not only hidden from view but also buttress a narrative in which young women are situated as children, and their sexuality and desire rendered pathological and morally unacceptable as judged by a conservative standard of decency. Comparison of the treatment of sexualisation and gender stereotyping in the review is revealing of the political motivations behind it, and of wider discourse in these areas
A Lagrangian scheme for the solution of nonlinear diffusion equations using moving simplex meshes
A Lagrangian numerical scheme for solving nonlinear degenerate Fokker{Planck equations in space dimensions d>2 is presented. It applies to a large class of nonlinear diffusion equations, whose dynamics are driven by internal energies and given external potentials, e.g. the porous medium equation and the fast diffusion equation. The key ingredient in our approach is the gradient ow structure of the dynamics. For discretization of the Lagrangian map, we use a finite subspace of linear maps in space and a variational form of the implicit Euler method in time. Thanks to that time discretisation, the fully discrete solution inherits energy estimates from the original gradient ow, and these lead to weak compactness of the trajectories in the continuous limit. Consistency is analyzed in the planar situation, d = 2. A variety of numerical experiments for the porous medium equation indicates that the scheme is well-adapted to track the growth of the solution's support
One hundred years of EEG for brain and behaviour research
On the centenary of the first human EEG recording, more than 500 experts reflect on the impact that this discovery has had on our understanding of the brain and behaviour. We document their priorities and call for collective action focusing on validity, democratization and responsibility to realize the potential of EEG in science and society over the next 100 years
The Psychological Science Accelerator: Advancing Psychology through a Distributed Collaborative Network
Concerns have been growing about the veracity of psychological research. Many findings in psychological science are based on studies with insufficient statistical power and nonrepresentative samples, or may otherwise be limited to specific, ungeneralizable settings or populations. Crowdsourced research, a type of large-scale collaboration in which one or more research projects are conducted across multiple lab sites, offers a pragmatic solution to these and other current methodological challenges. The Psychological Science Accelerator (PSA) is a distributed network of laboratories designed to enable and support crowdsourced research projects. These projects can focus on novel research questions, or attempt to replicate prior research, in large, diverse samples. The PSA\u27s mission is to accelerate the accumulation of reliable and generalizable evidence in psychological science. Here, we describe the background, structure, principles, procedures, benefits, and challenges of the PSA. In contrast to other crowdsourced research networks, the PSA is ongoing (as opposed to time-limited), efficient (in terms of re-using structures and principles for different projects), decentralized, diverse (in terms of participants and researchers), and inclusive (of proposals, contributions, and other relevant input from anyone inside or outside of the network). The PSA and other approaches to crowdsourced psychological science will advance our understanding of mental processes and behaviors by enabling rigorous research and systematically examining its generalizability
Assessment of post-competition peak blood lactate in male and female master swimmers aged 40â79 years and its relationship with swimming performance
The main purpose of this study was to measure the postcompetition blood lactate concentration ([La]b) in master swimmers of both sexes aged between 40 and 79 years in order to relate it to age and swimming performance. One hundred and eight swimmers participating in the World Master Championships were assessed for [La]b and the average rate of lactate accumulation (Laâ;mmol l-1 s-1) was calculated. In addition, 77 of them were also tested for anthropometric measures. When the subjects were divided into 10-year age groups, males exhibited higher [La]b than women (factorial ANOVA, P < 0.01) and a steeper decline with ageing than female subjects. Overall, mean values (SD) of [La]b were 10.8 (2.8), 10.3 (2.0), 10.3 (1.9), 8.9 (3.2) mmol l-1 in women, and 14.2 (2.5), 12.4 (2.5), 11.0 (1.6), 8.2 (2.0) mmol l-1 in men for, respectively, 40â49, 50â59, 60â69, 70â79 yearsâ age groups. When, however, [La]b values were normalised for a ââspeed indexââ, which takes into account swimming speed as a percentage of world record, these sex-related differences, although still present, were considerably attenuated. Furthermore, the differences in Laâ between males and females were larger in the 40â49 age group (0.34 vs 0.20 mmol l-1 s-1 for 50-m distance) than in the 70â79 age group (0.12 vs 0.14 mmol l-1 s-1 for 50-m distance). Different physiological factors, supported by the considered anthropometric measurements, are suggested to explain the results
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Trust in scientific information mediates associations between conservatism and coronavirus responses in the U.S., but few other nations
U.S.-based research suggests conservatism is linked with less concern about contracting coronavirus and less preventative behaviors to avoid infection. Here, we investigate whether these tendencies are partly attributable to distrust in scientific information, and evaluate whether they generalize outside the U.S., using public data and recruited representative samples across three studies (Ntotal = 34,710). In Studies 1 and 2, we examine these relationships in the U.S., yielding converging evidence for a sequential indirect effect of conservatism on compliance through scientific (dis)trust and infection concern. In Study 3, we compare these relationships across 19 distinct countries. Although the relationships between trust in scientific information about the coronavirus, concern about coronavirus infection, and compliance are consistent cross-nationally, the relationships between conservatism and trust in scientific information are not. These relationships are strongest in North America. Consequently, the indirect effects observed in Studies 1â2 only replicate in North America (the U.S. and Canada) and in Indonesia. Study 3 also found parallel direct and indirect effects on support for lockdown restrictions. These associations suggest not only that relationships between conservatism and compliance are not universal, but localized to particular countries where conservatism is more strongly related to trust in scientific information about the coronavirus pandemic
Low loss coatings for the VIRGO large mirrors
présentée par L. PinardThe goal of the VIRGO program is to build a giant Michelson type interferometer (3 kilometer long arms) to detect gravitational waves. Large optical components (350 mm in diameter), having extremely low loss at 1064 nm, are needed. Today, the Ion beam Sputtering is the only deposition technique able to produce optical components with such performances. Consequently, a large ion beam sputtering deposition system was built to coat large optics up to 700 mm in diameter. The performances of this coater are described in term of layer uniformity on large scale and optical losses (absorption and scattering characterization). The VIRGO interferometer needs six main mirrors. The first set was ready in June 2002 and its installation is in progress on the VIRGO site (Italy). The optical performances of this first set are discussed. The requirements at 1064 nm are all satisfied. Indeed, the absorption level is close to 1 ppm (part per million), the scattering is lower than 5 ppm and the R.M.S. wavefront of these optics is lower than 8 nm on 150 mm in diameter. Finally, some solutions are proposed to further improve these performances, especially the absorption level (lower than 0.1 ppm) and the mechanical quality factor Q of the mirrors (thermal noise reduction)
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