263 research outputs found

    Dark Energy or Apparent Acceleration Due to a Relativistic Cosmological Model More Complex than FLRW?

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    We use the Szekeres inhomogeneous relativistic models in order to fit supernova combined data sets. We show that with a choice of the spatial curvature function that is guided by current observations, the models fit the supernova data almost as well as the LCDM model without requiring a dark energy component. The Szekeres models were originally derived as an exact solution to Einstein's equations with a general metric that has no symmetries and are regarded as good candidates to model the true lumpy universe that we observe. The null geodesics in these models are not radial. The best fit model found is also consistent with the requirement of spatial flatness at CMB scales. The first results presented here seem to encourage further investigations of apparent acceleration using various inhomogeneous models and other constraints from CMB and large structure need to be explored next.Comment: 6 pages, 1 figure, matches version published in PR

    Toward a New Technology and Policy Program (TPP) Curriculum

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    The mission of the MIT Technology and Policy Program (TPP) is: “Provide an integrative education to scientists and engineers who wish to lead in the development and implementation of responsible strategies and policies for exploitation of technology for the benefit of their communities” (Hastings, 2000). Embedded in the TPP mission statement are several educational requirements: (1) a comprehensive and diverse set of solid analytical skills needed to develop and assess strategies and policies, (2) the flexibility to manage the conflicting interests and values that are present at all stages of the policy process, and (3) the ability to provide leadership at each stage in the policy process. With these concepts in mind, the TPP Curriculum Development Committee will work to place TPP at the forefront of educating the “leaders (researchers and practitioners) of the fields of technology and policy studies” (Hastings, 2000)

    Effect of formant frequency spacing on perceived gender in pre-pubertal children's voices

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    <div><p>Background</p><p>It is usually possible to identify the sex of a pre-pubertal child from their voice, despite the absence of sex differences in fundamental frequency at these ages. While it has been suggested that the overall spacing between formants (formant frequency spacing - ΔF) is a key component of the expression and perception of sex in children's voices, the effect of its continuous variation on sex and gender attribution has not yet been investigated.</p><p>Methodology/Principal findings</p><p>In the present study we manipulated voice ΔF of eight year olds (two boys and two girls) along continua covering the observed variation of this parameter in pre-pubertal voices, and assessed the effect of this variation on adult ratings of speakers' sex and gender in two separate experiments. In the first experiment (sex identification) adults were asked to categorise the voice as either male or female. The resulting identification function exhibited a gradual slope from male to female voice categories. In the second experiment (gender rating), adults rated the voices on a continuum from “masculine boy” to “feminine girl”, gradually decreasing their masculinity ratings as ΔF increased.</p><p>Conclusions/Significance</p><p>These results indicate that the role of ΔF in voice gender perception, which has been reported in adult voices, extends to pre-pubertal children's voices: variation in ΔF not only affects the perceived sex, but also the perceived masculinity or femininity of the speaker. We discuss the implications of these observations for the expression and perception of gender in children's voices given the absence of anatomical dimorphism in overall vocal tract length before puberty.</p></div

    Tunable inductive coupler for high fidelity gates between fluxonium qubits

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    The fluxonium qubit is a promising candidate for quantum computation due to its long coherence times and large anharmonicity. We present a tunable coupler that realizes strong inductive coupling between two heavy-fluxonium qubits, each with ∌50\sim50MHz frequencies and ∌5\sim5 GHz anharmonicities. The coupler enables the qubits to have a large tuning range of XX\textit{XX} coupling strengths (−35-35 to 7575 MHz). The ZZ\textit{ZZ} coupling strength is <3<3kHz across the entire coupler bias range, and <100<100Hz at the coupler off-position. These qualities lead to fast, high-fidelity single- and two-qubit gates. By driving at the difference frequency of the two qubits, we realize a iSWAP\sqrt{i\mathrm{SWAP}} gate in 258258ns with fidelity 99.72%99.72\%, and by driving at the sum frequency of the two qubits, we achieve a bSWAP\sqrt{b\mathrm{SWAP}} gate in 102102ns with fidelity 99.91%99.91\%. This latter gate is only 5 qubit Larmor periods in length. We run cross-entropy benchmarking for over 2020 consecutive hours and measure stable gate fidelities, with bSWAP\sqrt{b\mathrm{SWAP}} drift (2σ2 \sigma) <0.02%< 0.02\% and iSWAP\sqrt{i\mathrm{SWAP}} drift <0.08%< 0.08\%.Comment: 16 pages, 14 figure

    A translational framework for public health research

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    &lt;p&gt;&lt;b&gt;Background&lt;/b&gt;&lt;/p&gt; &lt;p&gt;The paradigm of translational medicine that underpins frameworks such as the Cooksey report on the funding of health research does not adequately reflect the complex reality of the public health environment. We therefore outline a translational framework for public health research.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Discussion&lt;/b&gt;&lt;/p&gt; &lt;p&gt;Our framework redefines the objective of translation from that of institutionalising effective interventions to that of improving population health by influencing both individual and collective determinants of health. It incorporates epidemiological perspectives with those of the social sciences, recognising that many types of research may contribute to the shaping of policy, practice and future research. It also identifies a pivotal role for evidence synthesis and the importance of non-linear and intersectoral interfaces with the public realm.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Summary&lt;/b&gt;&lt;/p&gt; &lt;p&gt;We propose a research agenda to advance the field and argue that resources for 'applied' or 'translational' public health research should be deployed across the framework, not reserved for 'dissemination' or 'implementation'.&lt;/p&gt

    What is dust? - Physical foundations of the averaging problem in cosmology

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    The problems of coarse-graining and averaging of inhomogeneous cosmologies, and their backreaction on average cosmic evolution, are reviewed from a physical viewpoint. A particular focus is placed on comparing different notions of average spatial homogeneity, and on the interpretation of observational results. Among the physical questions we consider are: the nature of an average Copernican principle, the role of Mach's principle, the issue of quasilocal gravitational energy and the different roles of spacetime, spatial and null cone averages. The observational interpretation of the timescape scenario is compared to other approaches to cosmological averaging, and outstanding questions are discussed.Comment: 39 pages, 3 figures, Invited review accepted by Classical and Quantum Gravity for the special issue "Inhomogeneous Cosmological Models and Averaging in Cosmology

    Natural course of behavioral addictions: A 5-year longitudinal study

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    BACKGROUND: Resolving the theoretical controversy on the labeling of an increasing number of excessive behaviors as behavioral addictions may also be facilitated by more empirical data on these behavioral problems. For instance, an essential issue to the classification of psychiatric disorders is information on their natural course. However, longitudinal research on the chronic vs. episodic nature of behavioral addictions is scarce. The aim of the present study, therefore, was to provide data on prevalence, substance use comorbidity, and five-year trajectories of six excessive behaviors—namely exercising, sexual behavior, shopping, online chatting, video gaming, and eating. METHODS: Analyses were based on the data of the Quinte Longitudinal Study, where a cohort of 4,121 adults from Ontario, Canada was followed for 5 years (2006 to 2011). The response rate was 21.3%, while retention rate was 93.9%. To assess the occurrence of each problem behavior, a single self-diagnostic question asked people whether their over-involvement in the behavior had caused significant problems for them in the past 12 months. To assess the severity of each problem behavior reported, the Behavioral Addiction Measure was administered. A mixed design ANOVA was used to investigate symptom trajectories over time for each problem behavior and whether these symptom trajectories varied as a function of sex. RESULTS: The large majority of people reported having problematic over-involvement for just one of these behaviors and just in a single time period. A main effect of time was found for each problem behavior, indicating a moderately strong decrease in symptom severity across time. The time x sex interaction was insignificant in each model indicating that the decreasing trend is similar for males and females. The data also showed that help seeking was very low in the case of excessive sexual behavior, shopping, online chatting, and video gaming but substantially more prevalent in the case of excessive eating and exercising. CONCLUSIONS: The present results indicate that self-identified excessive exercising, sexual behavior, shopping, online chatting, video gaming, and/or eating tend to be fairly transient for most people. This aspect of the results is inconsistent with conceptualizations of addictions as progressive in nature, unless treated. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12888-015-0383-3) contains supplementary material, which is available to authorized users

    Primary hyperaldosteronism caused by adrenocortical carcinoma

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    Since the syndrome of primary hyperaldosteronism was described by Jerome Conn in 1955, over 300 patients with this disorder have been identified in the medical centers of Vanderbilt University and the University of Michigan. The most frequent cause of this endocrinopathy has been a solitary adenoma of the adrenal cortex (72%); bilateral adrenocortical hyperplasia has been the cause of primary hyperaldosteronism in 27% of cases; less frequently, the cause has been multiple and/or bilateral adenomas (1%). During the last 4 years in these 2 medical centers, we have encountered 3 patients who have had biochemically proven primary hyperaldosteronism due to adrenocortical carcinoma. Each of these unusual cases is summarized with review of the recent literature . Depuis que le syndrome d'hyperaldostĂ©ronisme primitif a Ă©tĂ© dĂ©crit par JerĂŽme Conn en 1955 plus de 300 sujets qui en Ă©taient victimes ont Ă©tĂ© identifiĂ©s Ă  la Vanderbilt University de Nashville et Ă  l'University of Michigan de Ann Arbor. La cause la plus frĂ©quente de cette endocrinopathie rĂ©pond Ă  un adĂ©nome solitaire de la cortico-surrĂ©nale (72%) alors que l'hyperplasie corticale des 2 surrĂ©nales est plus rarement Ă  son origine (27%), les adĂ©nomes multiples et/ou bilatĂ©raux Ă©tant rarissimes (1%). Au cours des 4 derniĂšres annĂ©es 3 cas d'hyperaldosteronisme dĂ» Ă  un cancer de la cortico-surrĂ©nale ont Ă©tĂ© observĂ©s dans les 2 centres. Chacun de ces cas exceptionnels est exposĂ© cependant que la littĂ©rature rĂ©cente concernant l'hyperalderosteronisme est analysĂ©e. Desde la descripciĂłn del sĂ­ndrome de hiperaldosteronismo primario por Jeremo Conn en 1955, mĂĄs de 300 pacientes con esta entidad han sido identificados en nuestros 2 centros mĂ©dicos, la Universidad de Vanderbilt (Nashville) y la Universidad de Michigan (Ann Arbor). La causa mĂĄs frecuente de esta endocrinopatĂ­a ha sido el adenoma solitario de la corteza suprarrenal (72%); la hiperplasia adrenocortical bilateral ha sido la causa del hiperaldosteronismo primario en 27% de los casos; con menor frecuencia se han presentado los adenomas multiples y/o bilaterales (1%). En los 4 Ășltimos años hemos encontrado 3 pacientes con hiperaldosteronismo primario comprobado bioquĂ­micamente producido por carcinoma adrenocortical. Se presenta cada uno de estos casos poco usuales junto con una revisiĂłn de la literatura reciente.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41275/1/268_2005_Article_BF01655546.pd
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