690 research outputs found

    Test of Information Theory on the Boltzmann Equation

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    We examine information theory using the steady-state Boltzmann equation. In a nonequilibrium steady-state system under steady heat conduction, the thermodynamic quantities from information theory are calculated and compared with those from the steady-state Boltzmann equation. We have found that information theory is inconsistent with the steady-state Boltzmann equation.Comment: 12 page

    Some thoughts about nonequilibrium temperature

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    The main objective of this paper is to show that, within the present framework of the kinetic theoretical approach to irreversible thermodynamics, there is no evidence that provides a basis to modify the ordinary Fourier equation relating the heat flux in a non-equilibrium steady state to the gradient of the local equilibrium temperature. This fact is supported, among other arguments, through the kinetic foundations of generalized hydrodynamics. Some attempts have been recently proposed asserting that, in the presence of non-linearities of the state variables, such a temperature should be replaced by the non-equilibrium temperature as defined in Extended Irreversible Thermodynamics. In the approximations used for such a temperature there is so far no evidence that sustains this proposal.Comment: 13 pages, TeX, no figures, to appear in Mol. Phy

    Information theory in the study of anisotropic radiation

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    Information theory is used to perform a thermodynamic study of non equilibrium anisotropic radiation. We limit our analysis to a second-order truncation of the moments, obtaining a distribution function which leads to a natural closure of the hierarchy of radiative transfer equations in the so-called variable Eddington factor scheme. Some Eddington factors appearing in the literature can be recovered as particular cases of our two-parameter Eddington factor. We focus our attention in the study of the thermodynamic properties of such systems and relate it to recent nonequilibrium thermodynamic theories. Finally we comment the possibility of introducing a nonequilibrium chemical potential for photons.Comment: 1 eps figure upon request by e-mail, to appear in Journal of Physics

    Diet Soda Intake and Risk of Incident Metabolic Syndrome and Type 2 Diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA)*

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    Stereo imaging is an important area of image and video processing, with exploding progress in the last decades. An open issue in this field is the understanding of the conditions under which the straightforward application of a given image processing operator to both the left and right image of a stereo pair preserves the stereoscopic perception. In this paper, we explore this problem with application to artistic imaging and we prove that, unlike other methods, artistic operators based on edge preserving smoothing have this desirable property. We also present a novel multiresolution artistic operator, purposely designed for stereo images, which enhances the perception of three-dimensionality by means of a depth driven local scale control.

    Nonequilibrium corrections in the pressure tensor due to an energy flux

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    The physical interpretation of the nonequilibrium corrections in the pressure tensor for radiation submitted to an energy flux obtained in some previous works is revisited. Such pressure tensor is shown to describe a moving equilibrium system but not a real nonequilibrium situation.Comment: 4 pages, REVTeX, Brief Report to appear in PRE Dec 9

    Beings in their own right? Exploring Children and young people's sibling and twin relationships in the Minority World

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    This paper examines the contributions that the sociological study of sibship and twinship in the Minority World can make to childhood studies. It argues that, in providing one forum within which to explore children and young people's social relationships, we can add to our understanding of children and young people's interdependence and develop a more nuanced understanding of agency. As emergent subjects, children, young people and adults are in a process of ‘becoming’. However, this does not mean that they can ‘become’ anything they choose to. The notion of negotiated interdependence (Punch 2002) is useful in helping us to grasp the contingent nature of children and young people's agency

    M-health and health promotion: the digital cyborg and surveillance society

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    The new mobile wireless computer technologies and social media applications using Web 2.0 platforms have recently received attention from those working in health promotion as a promising new way of achieving their goals of preventing ill-health and promoting healthy behaviours at the population level. There is very little critical examination in this literature of how the use of these digital technologies may affect the targeted groups, in terms of the implications for how individuals experience embodiment, selfhood and social relationships. This article addresses these issues, employing a range of social and cultural theories to do so. It is argued that m-health technologies produce a digital cyborg body. They are able to act not only as prostheses but also as interpreters of the body. The subject produced through the use of m-health technologies is constructed as both an object of surveillance and persuasion and as a responsible citizen who is willing and able to act on the health imperatives issuing forth from the technologies and to present their body/self as open to continual measurement and assessment. The implications of this new way of surveilling the body’s health are discussed

    Metabolomics and Incident Hypertension Among Blacks: The Atherosclerosis Risk in Communities Study

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    Development of hypertension is influenced by genes, environmental effects and their interactions, and the human metabolome is a measurable manifestation of gene-environment interaction. We explored the metabolomic antecedents of developing incident hypertension in a sample of African Americans, a population with a high prevalence of hypertension and its comorbidities. We examined 896 (565 females, aged 45–64 years) African American normotensives from the Atherosclerosis Risk in Communities (ARIC) Study, whose metabolome was measured in serum collected at the baseline examination and analyzed by high throughput methods. The analyses presented here focus on 204 stably measured metabolites over a period of 4–6 weeks. Weibull parametric models considering interval censored data were used to assess the hazard ratio for incident hypertension. We used a modified Bonferroni correction accounting for the correlations among metabolites to define a threshold for statistical significance (p<3.9×10−4). During 10-years of follow-up, 38% of baseline normotensives developed hypertension (N=344). With adjustment for traditional risk factors and estimated glomerular filtration rate, each +1-standard deviation difference in baseline 4-hydroxyhippurate, a product of gut microbial fermentation, was associated with 17% higher risk of hypertension (p=2.5×10−4), which remained significant after adjusting for both baseline systolic and diastolic blood pressure (p=3.8×10−4). After principal component analyses, a sex steroids pattern was significantly associated with risk of incident hypertension (highest versus lowest quintile hazard ratio, 1.72; 95% CI, 1.05 to 2.82; p for trend=0.03), and stratified analyses suggested that this association was consistent in both genders. Metabolomic analyses identify novel pathways in the etiology of hypertension

    “A Faustian bargain?” Public voices on forensic DNA technologies and the National DNA Database

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    This article draws on the idea of the ‘forensic imaginary’ (Williams 2010) to explore UK public perspectives on the place, role and significance of forensic DNA technologies, both independent of and in relation to other genetic applications. Using correspondents’ replies to the Spring 2006 Mass Observation Directive ‘Genes, Genetics and Cloning’, the analysis focuses on continuities and tensions in their discursive repertoires. The argument examines (a) the ways in which knowledge is made sense of in these accounts, and (b) the discrepancy between an appreciation of the benefits of using DNA identification techniques in police work and a more critical attitude towards a wider national DNA database. The conclusion reflects on the need for a wider scope in research on public understandings of science, which looks beyond targeted consultations and specific publics, and provides more textured data to document collective views on the development and governance of forensic DNA technologies
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