848 research outputs found

    Exponential and moment inequalities for U-statistics

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    A Bernstein-type exponential inequality for (generalized) canonical U-statistics of order 2 is obtained and the Rosenthal and Hoffmann-J{\o}rgensen inequalities for sums of independent random variables are extended to (generalized) U-statistics of any order whose kernels are either nonnegative or canonicalComment: 22 page

    Thermoelectric Response of an Interacting Two-Dimensional Electron Gas in Quantizing Magnetic Field

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    We present a discussion of the linear thermoelectric response of an interacting electron gas in a quantizing magnetic field. Boundary currents can carry a significant fraction of the net current passing through the system. We derive general expressions for the bulk and boundary components of the number and energy currents. We show that the local current density may be described in terms of ``transport'' and ``internal magnetization'' contributions. The latter carry no net current and are not observable in standard transport experiments. We show that although Onsager relations cannot be applied to the local current, they are valid for the transport currents and hence for the currents observed in standard transport experiments. We relate three of the four thermoelectric response coefficients of a disorder-free interacting two-dimensional electron gas to equilibrium thermodynamic quantities. In particular, we show that the diffusion thermopower is proportional to the entropy per particle, and we compare this result with recent experimental observations.Comment: 18 pages, 2 postscript figures included. Revtex with epsf.tex and multicol.sty. In the revised version, the comparison with experimental observations at ν=1/2,3/2\nu=1/2, 3/2 is extended to include the possibility of corrections due to weak impurity scattering. The conclusions that we reach regarding the applicability of the composite fermion model at these filling fractions are not affecte

    Towards a Phenomenology of Grief : insights from Merleau-Ponty

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    This paper shows how phenomenological research can enhance our understanding of what it is to experience grief. I focus specifically on themes in the work of Maurice Merleau-Ponty, in order to develop an account that emphasizes two importantly different ways of experiencing indeterminacy. This casts light on features of grief that are disorienting and difficult to describe, while also making explicit an aspect of experience upon which the possibility of phenomenological inquiry itself depends

    Religiosity and corporate financial reporting: evidence from a European country

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    Using a sample of Portuguese privately-held firms, I examine the association between religiosity and financial reporting quality. The results suggest that firms headquartered in Portuguese areas with strong religious adherence and in the core area of the Portuguese religious cult (the district where the Fátima Sanctuary is located) generally experience lower incidence of earnings management. I provide further evidence that the results are robust to alternative measures of religiosity, and that are not driven by firms headquartered in rural areas. I also conclude that religious social norms, together with other forms of external financial monitoring, represent a mechanism for reducing costly agency conflicts. While the religious practice declined in the last decades in Portugal, I provide evidence that, even in a such context, religiosity is associated with reduced acceptance of unethical business practices, in particular, with reduced acceptance of aggressive accounting practices.I thank participants of the Second Paris Financial Management Conference (PFMC, 2014) and the 3RD Workshop on Business Ethics (EIASM, 2015) for their helpful insights.info:eu-repo/semantics/publishedVersio

    Runaway Events Dominate the Heavy Tail of Citation Distributions

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    Statistical distributions with heavy tails are ubiquitous in natural and social phenomena. Since the entries in heavy tail have disproportional significance, the knowledge of its exact shape is very important. Citations of scientific papers form one of the best-known heavy tail distributions. Even in this case there is a considerable debate whether citation distribution follows the log-normal or power-law fit. The goal of our study is to solve this debate by measuring citation distribution for a very large and homogeneous data. We measured citation distribution for 418,438 Physics papers published in 1980-1989 and cited by 2008. While the log-normal fit deviates too strong from the data, the discrete power-law function with the exponent γ=3.15\gamma=3.15 does better and fits 99.955% of the data. However, the extreme tail of the distribution deviates upward even from the power-law fit and exhibits a dramatic "runaway" behavior. The onset of the runaway regime is revealed macroscopically as the paper garners 1000-1500 citations, however the microscopic measurements of autocorrelation in citation rates are able to predict this behavior in advance.Comment: 6 pages, 5 Figure

    Hormonal Signal Amplification Mediates Environmental Conditions during Development and Controls an Irreversible Commitment to Adulthood

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    Many animals can choose between different developmental fates to maximize fitness. Despite the complexity of environmental cues and life history, different developmental fates are executed in a robust fashion. The nematode Caenorhabditis elegans serves as a powerful model to examine this phenomenon because it can adopt one of two developmental fates (adulthood or diapause) depending on environmental conditions. The steroid hormone dafachronic acid (DA) directs development to adulthood by regulating the transcriptional activity of the nuclear hormone receptor DAF-12. The known role of DA suggests that it may be the molecular mediator of environmental condition effects on the developmental fate decision, although the mechanism is yet unknown. We used a combination of physiological and molecular biology techniques to demonstrate that commitment to reproductive adult development occurs when DA levels, produced in the neuroendocrine XXX cells, exceed a threshold. Furthermore, imaging and cell ablation experiments demonstrate that the XXX cells act as a source of DA, which, upon commitment to adult development, is amplified and propagated in the epidermis in a DAF-12 dependent manner. This positive feedback loop increases DA levels and drives adult programs in the gonad and epidermis, thus conferring the irreversibility of the decision. We show that the positive feedback loop canalizes development by ensuring that sufficient amounts of DA are dispersed throughout the body and serves as a robust fate-locking mechanism to enforce an organism-wide binary decision, despite noisy and complex environmental cues. These mechanisms are not only relevant to C. elegans but may be extended to other hormonal-based decision-making mechanisms in insects and mammals

    Stability and change the role of keepsakes and family homes in the lives of parentally bereaved young adults in the Netherlands 1

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    This paper examines the loss of a parent in young adulthood, showing how this emergent and distinctive life stage shapes Dutch young people’s experience of bereavement. Youth material cultures have commonly been analysed in terms of the construction and expression of youth identities, for example, through style, music and leisure. In this research, we highlight three themes in young people’s relationship to material culture as part of their everyday lived experience of parental loss: first, the parental home as a space of departure, memory and return, and the potential for conflict, destabilisation and misunderstanding when the remaining parent transforms the home or embarks on a new relationship; second, the different strategies young adults use to commemorate their parent in their own temporary or shared accommodation and online space; and third, the role of small, portable but effective keepsakes and adornment, such as jewellery or tattoos, that meet their need for the emotional experience of closeness with the memory of their parent. A focus on the material trajectories of grief grants insights into how young adults cope with loss in their everyday life, generating understanding of the ways young people may support themselves and be supported by others in the context of parental bereavement

    A Response to the IPCC Fifth Assessment

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    This collection of essays is the initial product of the second meeting of the Environmental Law Collaborative, a group of environmental law scholars that meet to discuss important and timely environmental issues. Here, the group provides an array of perspectives arising from the Fifth Assessment of the Intergovernmental Panel on Climate Change. Each scholar chose one passage from one of the IPCC’s three Summaries for Policymakers as a jumping-off point for exploring climate change issues and responding directly to the reports. The result is a variety of viewpoints on the future of how law relates to climate change, a result that is the product not only of each scholar’s individual knowledge but also of the group’s robust discussion

    Phenotypic covariance of longevity, immunity and stress resistance in the Caenorhabditis nematodes

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    Background \ud Ageing, immunity and stresstolerance are inherent characteristics of all organisms. In animals, these traits are regulated, at least in part, by forkhead transcription factors in response to upstream signals from the Insulin/Insulin– like growth factor signalling (IIS) pathway. In the nematode Caenorhabditis elegans, these phenotypes are molecularly linked such that activation of the forkhead transcription factor DAF-16 both extends lifespan and simultaneously increases immunity and stress resistance. It is known that lifespan varies significantly among the Caenorhabditis species but, although DAF-16 signalling is highly conserved, it is unclear whether this phenotypic linkage occurs in other species. Here we investigate this phenotypic covariance by comparing longevity, stress resistance and immunity in four \ud Caenorhabditis species. \ud \ud Methodology/Principal Findings \ud We show using phenotypic analysis of DAF-16 influenced phenotypes that among four closely related Caenorhabditis nematodes, the gonochoristic species (Caenorhabditis remanei and Caenorhabditis brenneri) have diverged \ud significantly with a longer lifespan, improved stress resistance and higher immunity than the hermaphroditic species (C. elegans and Caenorhabditis briggsae). Interestingly, we also observe significant differences in expression levels between the daf-16 homologues in these species using Real-Time PCR, which positively correlate with the observed phenotypes. Finally, we provide additional evidence in support of a role for DAF-16 in regulating phenotypic coupling by using a combination of wildtype isolates, constitutively active daf-16 mutants and bioinformatic analysis. \ud \ud Conclusions \ud The gonochoristic species display a significantly longer lifespan (p < 0.0001)and more robust immune and stress response (p<0.0001, thermal stress; p<0.01, heavy metal stress; p<0.0001, pathogenic stress) than the hermaphroditic species. Our data suggests that divergence in DAF-16 mediated phenotypes may underlie many of the differences observed between these four species of Caenorhabditis nematodes. These findings are further supported by the correlative higher daf-16 expression levels among the gonochoristic species and significantly higher lifespan, immunity and stress tolerance in the constitutively active daf-16 hermaphroditic mutants
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