5,583 research outputs found

    Convergence of continuous-time quantum walks on the line

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    The position density of a "particle" performing a continuous-time quantum walk on the integer lattice, viewed on length scales inversely proportional to the time t, converges (as t tends to infinity) to a probability distribution that depends on the initial state of the particle. This convergence behavior has recently been demonstrated for the simplest continuous-time random walk [see quant-ph/0408140]. In this brief report, we use a different technique to establish the same convergence for a very large class of continuous-time quantum walks, and we identify the limit distribution in the general case.Comment: Version to appear in Phys. Rev.

    Uberzeugender Beweis aus der Vernunft von der Unsterblichkeit sowohl der Menschen Seelen insgemein, als besonders der Kinder-Seelen

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    Israel Gottlieb Canz’s Uberzeugender Beweiß, first published in 1741 and reprinted here in its second, expanded edition stands as his most influential discussion of the soul’s immortality, with one contemporary pronouncing it to be “one of the best [treatments of immortality] that we have.” In this text, Canz seeks to augment and supplement traditional Wolffian proofs by considering, first, the grounds for the soul’s immortality that are contained in its own nature and, second, the grounds for the same that are found in God. In addition, Canz extends his treatment to include a detailed discussion of the souls of children and he offers speculations concerning the soul’s condition in the afterlife. On account of its systematic presentation and original argumentation, Canz’s Beweiß represents a key contribution to Leibniz-Wolffian rational psychology, and through the critical reaction it generated it would help shape the debate concerning the soul’s immortality for years after its original publication

    Entropy Change through Rayleigh-B\'enard Convective Transition with Rigid Boundaries

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    The previous investigation on Rayleigh-B\'enard convection of a dilute classical gas [T. Kita: J. Phys. Soc. Jpn. {\bf 75} (2006) 124005] is extended to calculate entropy change of the convective transition with the rigid boundaries. We obtain results qualitatively similar to those of the stress-free boundaries. Above the critical Rayleigh number, the roll convection is realized among possible steady states with periodic structures, carrying the highest entropy as a function of macroscopic mechanical variables.Comment: 5 pages, 4 figure

    Screening for Park Access during a Primary Care Social Determinants Screen.

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    While there is evidence that access to nature and parks benefits pediatric health, it is unclear how low-income families living in an urban center acknowledge or prioritize access to parks.MethodsWe conducted a study about access to parks by pediatric patients in a health system serving low-income families. Adult caregivers of pediatric patients completed a survey to identify and prioritize unmet social and economic needs, including access to parks. Univariate and multivariate analyses were conducted to explore associations between lack of access to parks and sociodemographic variables. We also explored the extent to which access to parks competed with other needs.ResultsThe survey was completed by 890 caregivers; 151 (17%) identified "access to green spaces/parks/playgrounds" as an unmet need, compared to 397 (45%) who endorsed "running out of food before you had money or food stamps to buy more". Being at or below the poverty line doubled the odds ( Odds ratio 1.96, 95% CI 1.16-3.31) of lacking access to a park (reference group: above the poverty line), and lacking a high school degree nearly doubled the odds. Thirty-three of the 151 (22%) caregivers who identified access to parks as an unmet need prioritized it as one of three top unmet needs. Families who faced competing needs of housing, food, and employment insecurity were less likely to prioritize park access (p < 0.001).ConclusionClinical interventions to increase park access would benefit from an understanding of the social and economic adversity faced by patients

    Computational problems in autoregressive moving average (ARMA) models

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    The choice of the sampling interval and the selection of the order of the model in time series analysis are considered. Band limited (up to 15 Hz) random torque perturbations are applied to the human ankle joint. The applied torque input, the angular rotation output, and the electromyographic activity using surface electrodes from the extensor and flexor muscles of the ankle joint are recorded. Autoregressive moving average models are developed. A parameter constraining technique is applied to develop more reliable models. The asymptotic behavior of the system must be taken into account during parameter optimization to develop predictive models

    Two-Flavor Staggered Fermion Thermodynamics at N_t = 12

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    We present results of an ongoing study of the nature of the high temperature crossover in QCD with two light fermion flavors. These results are obtained with the conventional staggered fermion action at the smallest lattice spacing to date---approximately 0.1 fm. Of particular interest are a study of the temperature of the crossover a determination of the induced baryon charge and baryon susceptibility, the scalar susceptibility, and the chiral order parameter, used to test models of critical behavior associated with chiral symmetry restoration. From our new data and published results for N_t = 4, 6, and 8, we determine the QCD magnetic equation of state from the chiral order parameter using O(4) and mean field critical exponents and compare it with the corresponding equation of state obtained from an O(4) spin model and mean field theory. We also present a scaling analysis of the Polyakov loop, suggesting a temperature dependent ``constituent quark free energy.''Comment: LaTeX 25 pages, 15 Postscript figure

    Two Theories of Transparency

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    Perceptual experience is often said to be transparent; that is, when we have a perceptual experience we seem to be aware of properties of the objects around us, and never seem to be aware of properties of the experience itself. This is a introspective fact. It is also often said that we can infer a metaphysical fact from this introspective fact, e.g. a fact about the nature of perceptual experience. A transparency theory fills in the details for these two facts, and bridges the gap between them. We have three aims: to scrutinize Michael Tye’s transparency theory :137–151, 2002; Consciousness revisited: materialism without phenomenal concepts, MIT Press, Cambridge, 2009; Philos Stud 170:39–57, 2014a), introduce a new transparency theory, and advance a meta-theoretical hypothesis about the interest, and import, of transparency theories

    Academic Primer Series: Five Key Papers for Consulting Clinician Educators.

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    INTRODUCTION: Clinician educators are often asked to perform consultations for colleagues. Invitations to consult and advise others on local problems can help foster great collaborations between centers, and allows for an exchange of ideas between programs. In this article, the authors identify and summarize several key papers to assist emerging clinician educators with the consultation process. METHODS: A consensus-building process was used to generate a list of key papers that describe the importance and significance of educational consulting, informed by social media sources. A three-round voting methodology, akin to a Delphi study, determined the most impactful papers from the larger list. RESULTS: Summaries of the five most highly rated papers on education consultation are presented in this paper. These papers were determined by a mixed group of junior and senior faculty members, who have summarized these papers with respect to their relevance for their peer groups. CONCLUSION: Five key papers on the educational consultation process are presented in this paper. These papers offer background and perspective to help junior faculty gain a grasp of consultation processes

    Precise Determination of |V{us}| from Lattice Calculations of Pseudoscalar Decay Constants

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    Combining the ratio of experimental kaon and pion decay widths, Gamma(K to mu antineutrino{mu} (gamma)) / Gamma(pi to mu \antineutrino (gamma)), with a recent lattice gauge theory calculation of f{K}/f{pi} provides a precise value for the CKM quark mixing matrix element |V{us}|=0.2236(30) or if 3 generation unitarity is assumed |V{us}|=0.2238(30). Comparison with other determinations of that fundamental parameter, implications, and an outlook for future improvements are given

    Thermodynamical quantities of lattice full QCD from an efficient method

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    I extend to QCD an efficient method for lattice gauge theory with dynamical fermions. Once the eigenvalues of the Dirac operator and the density of states of pure gluonic configurations at a set of plaquette energies (proportional to the gauge action) are computed, thermodynamical quantities deriving from the partition function can be obtained for arbitrary flavor number, quark masses and wide range of coupling constants, without additional computational cost. Results for the chiral condensate and gauge action are presented on the 10410^4 lattice at flavor number Nf=0N_f=0, 1, 2, 3, 4 and many quark masses and coupling constants. New results in the chiral limit for the gauge action and its correlation with the chiral condensate, which are useful for analyzing the QCD chiral phase structure, are also provided.Comment: Latex, 11 figures, version accepted for publicatio
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