1,258 research outputs found

    African-Americans in Standard Behavioral Treatment for Obesity, 2001-2015: What have we learned?

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    African Americans (AAs) bear a disproportionate burden of the obesity epidemic, yet have historically been underrepresented in weight loss research. We conducted a narrative review of large (N > 75) randomized prospective clinical trials of standard behavioral treatment for weight loss that reported results in the past 15 years (2001-2015) to (a) determine the rates of inclusion and reported results for AAs and (b) further identify strategies that may result in improved outcomes. Of the 23 trials reviewed, 69.6% of the studies met or exceeded population estimates for AAs in the United States. However, only 10 reported outcomes and/or considered race in the analytic approach. At 6 months, AA participants consistently lost less weight than White participants. The use of culturally tailored intervention materials and monthly personal telephone calls were reported as factors that may have enhanced treatment response. Future behavioral weight loss trials should also increase reporting of outcomes by race

    A scalar-tensor cosmological model with dynamical light velocity

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    The dynamical consequences of a bimetric scalar-tensor theory of gravity with a dynamical light speed are investigated in a cosmological setting. The model consists of a minimally-coupled self-gravitating scalar field coupled to ordinary matter fields in the standard way through the metric: \metric_{\mu\nu}+B\partial_\mu\phi\partial_\nu\phi. We show that in a universe with matter that has a radiation-dominated equation of state, the model allows solutions with a de Sitter phase that provides sufficient inflation to solve the horizon and flatness problems. This behaviour is achieved without the addition of a potential for the scalar field, and is shown to be largely independent of its introduction. We therefore have a model that is fundamentally different than the potential-dominated, slowly-rolling scalar field of the standard models inflationary cosmology. The speed of gravitational wave propagation is predicted to be significantly different from the speed of matter waves and photon propagation in the early universe.Comment: 12 pages, uses amsart and amssymb. Minor corrections, to appear in Phys. Lett.

    Variable-Speed-of-Light Cosmology from Brane World Scenario

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    We argue that the four-dimensional universe on the TeV brane of the Randall-Sundrum scenario takes the bimetric structure of Clayton and Moffat, with gravitons traveling faster than photons instead, while the radion varies with time. We show that such brane world bimetric model can thereby solve the flatness and the cosmological constant problems, provided the speed of a graviton decreases to the present day value rapidly enough. The resolution of other cosmological problems such as the horizon problem and the monopole problem requires supplementation by inflation, which may be achieved by the radion field provided the radion potential satisfies the slow-roll approximation.Comment: 18 pages, LaTeX, revised version to appear in Phys. Rev.

    Distinguishing regional from within-codon rate heterogeneity in DNA sequence alignments

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    We present an improved phylogenetic factorial hidden Markov model (FHMM) for detecting two types of mosaic structures in DNA sequence alignments, related to (1) recombination and (2) rate heterogeneity. The focus of the present work is on improving the modelling of the latter aspect. Earlier papers have modelled different degrees of rate heterogeneity with separate hidden states of the FHMM. This approach fails to appreciate the intrinsic difference between two types of rate heterogeneity: long-range regional effects, which are potentially related to differences in the selective pressure, and the short-term periodic patterns within the codons, which merely capture the signature of the genetic code. We propose an improved model that explicitly distinguishes between these two effects, and we assess its performance on a set of simulated DNA sequence alignments

    A time-space varying speed of light and the Hubble Law in static Universe

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    We consider a hypothetical possibility of the variability of light velocity with time and position in space which is derived from two natural postulates. For the consistent consideration of such variability we generalize translational transformations of the Theory of Relativity. The formulae of transformations between two rest observers within one inertial system are obtained. It is shown that equality of velocities of two particles is as relative a statement as simultaneity of two events is. We obtain the expression for the redshift of radiation of a rest source which formally reproduces the Hubble Law. Possible experimental implications of the theory are discussed.Comment: 7 page

    Perceptions and experiences of appetite awareness training among African-American women who binge eat

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    Introduction: Binge eating may contribute to the prevalence of obesity in African-American women. Yet, there has been scant intervention research on the treatment of binge eating in this population. We tested the feasibility of an appetite awareness training (AAT) intervention in a sample of African-American women with binge and overeating behaviors. Participants who completed AAT were recruited to participate in focus groups to elicit information about their perceptions and experiences with this intervention to inform the design of future interventions to treat binge eating and obesity in African-American women. Methods: African-American women, aged 18–70 years, who had completed an 8-week randomized AAT intervention, were invited to attend a focus group discussion. Session content was recorded and transcribed. Data were analyzed by use of open coding. Themes were identified that described their perceptions and experiences of participating in the intervention. Results: Seventeen women participated in three focus group discussions. Pertinent themes identified included: paying attention to internal cues of hunger and satiety, influence of culture on eating patterns, breaking patterns of disordered eating, and perceptions about weight. Overall, participants were satisfied with their experience of AAT, and reported they found it valuable to learn about listening to biological signals of hunger and satiety and to learn specific strategies to reduce maladaptive eating patterns. Conclusion: AAT was acceptable and provided helpful eating behavior instruction to African-American women with reported binge and overeating behaviors. Future research should examine the potential of AAT to improve weight management in this underserved population. Level of evidence: Level V, qualitative descriptive study

    Neutron Stars in a Varying Speed of Light Theory

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    We study neutron stars in a varying speed of light (VSL) theory of gravity in which the local speed of light depends upon the value of a scalar field ϕ\phi. We find that the masses and radii of the stars are strongly dependent on the strength of the coupling between ϕ\phi and the matter field and that for certain choices of coupling parameters, the maximum neutron star mass can be arbitrarily small. We also discuss the phenomenon of cosmological evolution of VSL stars (analogous to the gravitational evolution in scalar-tensor theories) and we derive a relation showing how the fractional change in the energy of a star is related to the change in the cosmological value of the scalar field.Comment: 15 pages, 2 figures. Added solutions with a more realistic equation of state. To be published in PR

    Dynamical System Approach to Cosmological Models with a Varying Speed of Light

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    Methods of dynamical systems have been used to study homogeneous and isotropic cosmological models with a varying speed of light (VSL). We propose two methods of reduction of dynamics to the form of planar Hamiltonian dynamical systems for models with a time dependent equation of state. The solutions are analyzed on two-dimensional phase space in the variables (x,x˙)(x, \dot{x}) where xx is a function of a scale factor aa. Then we show how the horizon problem may be solved on some evolutional paths. It is shown that the models with negative curvature overcome the horizon and flatness problems. The presented method of reduction can be adopted to the analysis of dynamics of the universe with the general form of the equation of state p=Îł(a)Ï”p=\gamma(a)\epsilon. This is demonstrated using as an example the dynamics of VSL models filled with a non-interacting fluid. We demonstrate a new type of evolution near the initial singularity caused by a varying speed of light. The singularity-free oscillating universes are also admitted for positive cosmological constant. We consider a quantum VSL FRW closed model with radiation and show that the highest tunnelling rate occurs for a constant velocity of light if c(a)∝anc(a) \propto a^n and −1<n≀0-1 < n \le 0. It is also proved that the considered class of models is structurally unstable for the case of n<0n < 0.Comment: 18 pages, 5 figures, RevTeX4; final version to appear in PR
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