8,299 research outputs found

    Quenched Charmed Meson Spectra using Tadpole Improved Quark Action on Anisotropic Lattices

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    Charmed meson charmonium spectra are studied with improved quark actions on anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion relations for 4 lowest lattice momentum modes with quark mass values ranging from the strange quark to charm quark with 3 different values of gauge coupling β\beta and 4 different values of bare speed of light ν\nu. With the bare speed of light parameter ν\nu tuned in a mass-dependent way, we study the mass spectra of DD, DsD_s, ηc\eta_c, D∗D^{\ast}, Ds∗D_s^{\ast} and J/ψJ/\psi mesons. The results extrapolated to the continuum limit are compared with the experiment and qualitative agreement is found.Comment: 8 pages, 2 figures, latex fil

    Spatiotemporal complexity of a ratio-dependent predator-prey system

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    In this paper, we investigate the emergence of a ratio-dependent predator-prey system with Michaelis-Menten-type functional response and reaction-diffusion. We derive the conditions for Hopf, Turing and Wave bifurcation on a spatial domain. Furthermore, we present a theoretical analysis of evolutionary processes that involves organisms distribution and their interaction of spatially distributed population with local diffusion. The results of numerical simulations reveal that the typical dynamics of population density variation is the formation of isolated groups, i.e., stripelike or spotted or coexistence of both. Our study shows that the spatially extended model has not only more complex dynamic patterns in the space, but also chaos and spiral waves. It may help us better understand the dynamics of an aquatic community in a real marine environment.Comment: 6pages, revtex

    Quantum Thermodynamic Cycles and quantum heat engines

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    In order to describe quantum heat engines, here we systematically study isothermal and isochoric processes for quantum thermodynamic cycles. Based on these results the quantum versions of both the Carnot heat engine and the Otto heat engine are defined without ambiguities. We also study the properties of quantum Carnot and Otto heat engines in comparison with their classical counterparts. Relations and mappings between these two quantum heat engines are also investigated by considering their respective quantum thermodynamic processes. In addition, we discuss the role of Maxwell's demon in quantum thermodynamic cycles. We find that there is no violation of the second law, even in the existence of such a demon, when the demon is included correctly as part of the working substance of the heat engine.Comment: 17 pages, 9 figures, 4 table

    Access to and Use of Technology for Health: Comparisons Between Appalachian Kentuckians and the General U.S. Population

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    Introduction: Technology may increase the availability of health information and enable health promoting behaviors. However, lack of access to and use of technology may also exacerbate disparities, particularly in rural communities with limited Internet access. Purpose: The purpose of this study was to compare Internet access, device ownership, and use of technology for health between Appalachian Kentuckians and the general U.S. population. Methods: Findings from the 2017 Assessing the Health Status of Kentucky (ASK) survey were compared to national estimates from the Health Information National Trends Survey (HINTS) 5, Cycle 1 (2017), with a particular focus on degree of rurality. ASK and HINTS respondent sociodemographics, Internet access, and use of technology for health were assessed using weighted percentages; chi-square P-values were calculated based on weighted counts. Results: Over 80% of both populations reported accessing the Internet. However, Appalachian Kentuckians across all geographic strata were significantly less likely to access the Internet through broadband, cellular networks, and Wi-Fi. The U.S. population reported greater electronic device ownership rates. Appalachian Kentuckians were significantly more likely to search for cancer information online compared to national estimates. The majority of both populations reported not having health apps on their smartphones or tablets. Appalachian Kentuckians reported significantly lower rates of using electronic media to exchange information with health professionals. Implications: Ensuring high-speed Internet access among Appalachian Kentuckians could help this population leverage available technology to overcome barriers to care and reduce health disparities – for example, by enabling the use of health-related apps or electronic means to remotely communicate with providers. Such technologies have the potential to improve the health of medically underserved populations and deserve further attention

    The Zwicky Transient Facility: Surveys and Scheduler

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    We present a novel algorithm for scheduling the observations of time-domain imaging surveys. Our Integer Linear Programming approach optimizes an observing plan for an entire night by assigning targets to temporal blocks, enabling strict control of the number of exposures obtained per field and minimizing filter changes. A subsequent optimization step minimizes slew times between each observation. Our optimization metric self-consistently weights contributions from time-varying airmass, seeing, and sky brightness to maximize the transient discovery rate. We describe the implementation of this algorithm on the surveys of the Zwicky Transient Facility and present its on-sky performance.Comment: Published in PASP Focus Issue on the Zwicky Transient Facility (https://dx.doi.org/10.1088/1538-3873/ab0c2a). 13 Pages, 11 Figure

    Agephagy – Adapting Autophagy for Health During Aging

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    Autophagy is a major cellular recycling process that delivers cellular material and entire organelles to lysosomes for degradation, in a selective or non-selective manner. This process is essential for the maintenance of cellular energy levels, components, and metabolites, as well as the elimination of cellular molecular damage, thereby playing an important role in numerous cellular activities. An important function of autophagy is to enable survival under starvation conditions and other stresses. The majority of factors implicated in aging are modifiable through the process of autophagy, including the accumulation of oxidative damage and loss of proteostasis, genomic instability and epigenetic alteration. These primary causes of damage could lead to mitochondrial dysfunction, deregulation of nutrient sensing pathways and cellular senescence, finally causing a variety of aging phenotypes. Remarkably, advances in the biology of aging have revealed that aging is a malleable process: a mild decrease in signaling through nutrient-sensing pathways can improve health and extend lifespan in all model organisms tested. Consequently, autophagy is implicated in both aging and age-related disease. Enhancement of the autophagy process is a common characteristic of all principal, evolutionary conserved anti-aging interventions, including dietary restriction, as well as inhibition of target of rapamycin (TOR) and insulin/IGF-1 signaling (IIS). As an emerging and critical process in aging, this review will highlight how autophagy can be modulated for health improvement

    Heterotopic and Orthotopic Tracheal Transplantation in Mice used as Models to Study the Development of Obliterative Airway Disease

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    Obliterative airway disease (OAD) is the major complication after lung transplantations that limits long term survival (1-7)

    Entanglement in spin-one Heisenberg chains

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    By using the concept of negativity, we study entanglement in spin-one Heisenberg chains. Both the bilinear chain and the bilinear-biquadratic chain are considered. Due to the SU(2) symmetry, the negativity can be determined by two correlators, which greatly facilitate the study of entanglement properties. Analytical results of negativity are obtained in the bilinear model up to four spins and the two-spin bilinear-biquadratic model, and numerical results of negativity are presented. We determine the threshold temperature before which the thermal state is doomed to be entangled.Comment: 7 pages and 4 figure
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