497 research outputs found

    Spectral Theory for Non-linear Superconducting Microwave Systems: Extracting Relaxation Rates and Mode Hybridization

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    The accurate modeling of mode hybridization and calculation of radiative relaxation rates have been crucial to the design and optimization of superconducting quantum devices. In this work, we introduce a spectral theory for the electrohydrodynamics of superconductors that enables the extraction of the relaxation rates of excitations in a general three-dimensional distribution of superconducting bodies. Our approach addresses the long-standing problem of formulating a modal description of open systems that is both efficient and allows for second quantization of the radiative hybridized fields. This is achieved through the implementation of finite but transparent boundaries through which radiation can propagate into and out of the computational domain. The resulting spectral problem is defined within a coarse-grained formulation of the electrohydrodynamical equations that is suitable for the analysis of the non-equilibrium dynamics of multiscale superconducting quantum systems.Comment: 21 pages, 12 figures, journal pape

    The Prevalence of Wrist Wrap Use in Actively Competing Powerlifters

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    Wrist wraps are often ergogenically employed by competitive powerlifters to improve bench press performance, but several product-specific variations may impact any potential benefits. Moreover, the prevalence of athletic wrist wrap use is hitherto undescribed. PURPOSE: to characterize the pervasiveness of wrist wrap use amongst competitive powerlifters with regards to style (flexible [F] or stiff [S]), length, and tightness amongst competitive powerlifters. METHODS: Powerlifters (n = 70; 27±6y) who competed in the last two years were randomly recruited at sanctioned meets across the USA. After providing consent and following a 5-minute seated rest, participant wrist wrap use descriptive data (wrap style [F or S], wrap length, and events used) were collected. Additionally, wrap tightness was assessed via pulse oximeter-detected oxygen saturation (SpO2). Post-meet bench press one repetition maximum (1RM) was also recorded from the Openpowerlifting.com open database. Wrist wrap use prevalence data (wrap style [F or S], wrap length, and events used) were assessed across Central, West Coast, and East Coast regions via separate Pearson’s Chi-squared tests. Furthermore, the relationships between both region-collapsed wrapped SpO2 and bench press 1RM were assessed using Pearson’s product-moment correlations and all statistical analyses were set at a significance level of pRESULTS: Analyses failed to detect any significant regional differences in wrap style, length, or events used (p\u3e0.05). Furthermore, there was a weak, negative correlation between wrapped SpO2 and bench press 1RM (r = -0.393, p = 0.086). CONCLUSIONS: Although we failed to detect any significant relationships between performance and wrap tightness, actively competing powerlifters nonetheless prominently utilize wraps similarly across the US regions assessed. Therefore, the potential for wrist wraps to augment bench press performance warrants further elucidation in a controlled, standardized investigation

    Bosonizing one-dimensional cold atomic gases

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    We present results for the long-distance asymptotics of correlation functions of mesoscopic one-dimensional systems with periodic and open (Dirichlet) boundary conditions, as well as at finite temperature in the thermodynamic limit. The results are obtained using Haldane's harmonic-fluid approach (also known as ``bosonization''), and are valid for both bosons and fermions, in weakly and strongly interacting regimes. The harmonic-fluid approach and the method to compute the correlation functions using conformal transformations are explained in great detail. As an application relevant to one-dimensional systems of cold atomic gases, we consider the model of bosons interacting with a zero-range potential. The Luttinger-liquid parameters are obtained from the exact solution by solving the Bethe-ansatz equations in finite-size systems. The range of applicability of the approach is discussed, and the prefactor of the one-body density matrix of bosons is fixed by finding an appropriate parametrization of the weak-coupling result. The formula thus obtained is shown to be accurate, when compared with recent diffusion Montecarlo calculations, within less than 10%. The experimental implications of these results for Bragg scattering experiments at low and high momenta are also discussed.Comment: 39 pages + 14 EPS figures; typos corrected, references update

    Microstructural Alterations and Oligodendrocyte Dysmaturation in White Matter After Cardiopulmonary Bypass in a Juvenile Porcine Model.

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    BACKGROUND: Newly developed white matter (WM) injury is common after cardiopulmonary bypass (CPB) in severe/complex congenital heart disease. Fractional anisotropy (FA) allows measurement of macroscopic organization of WM pathology but has rarely been applied after CPB. The aims of our animal study were to define CPB-induced FA alterations and to determine correlations between these changes and cellular events after congenital heart disease surgery. METHODS AND RESULTS: Normal porcine WM development was first assessed between 3 and 7 weeks of age: 3-week-old piglets were randomly assigned to 1 of 3 CPB-induced insults. FA was analyzed in 31 WM structures. WM oligodendrocytes, astrocytes, and microglia were assessed immunohistologically. Normal porcine WM development resembles human WM development in early infancy. We found region-specific WM vulnerability to insults associated with CPB. FA changes after CPB were also insult dependent. Within various WM areas, WM within the frontal cortex was susceptible, suggesting that FA in the frontal cortex should be a biomarker for WM injury after CPB. FA increases occur parallel to cellular processes of WM maturation during normal development; however, they are altered following surgery. CPB-induced oligodendrocyte dysmaturation, astrogliosis, and microglial expansion affect these changes. FA enabled capturing CPB-induced cellular events 4 weeks postoperatively. Regions most resilient to CPB-induced FA reduction were those that maintained mature oligodendrocytes. CONCLUSIONS: Reducing alterations of oligodendrocyte development in the frontal cortex can be both a metric and a goal to improve neurodevelopmental impairment in the congenital heart disease population. Studies using this model can provide important data needed to better interpret human imaging studies

    Early postnatal ozone exposure alters rat nodose and jugular sensory neuron development

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    Sensory neurons originating in nodose and jugular ganglia that innervate airway epithelium (airway neurons) play a role in inflammation observed following exposure to inhaled environmental irritants such as ozone (O3). Airway neurons can mediate airway inflammation through the release of the neuropeptide substance P (SP). While susceptibility to airway irritants is increased in early life, the developmental dynamics of afferent airway neurons are not well characterized. The hypothesis of this study was that airway neuron number might increase with increasing age, and that an acute, early postnatal O3 exposure might increase both the number of sensory airway neurons as well as the number SP-containing airway neurons. Studies using Fischer 344 rat pups were conducted to determine if age or acute O3 exposure might alter airway neuron number. Airway neurons in nodose and jugular ganglia were retrogradely labeled, removed, dissociated, and counted by means of a novel technique employing flow cytometry. In Study 1, neuron counts were conducted on postnatal days (PD) 6, 10, 15, 21, and 28. Numbers of total and airway neurons increased significantly between PD6 and PD10, then generally stabilized. In Study 2, animals were exposed to O3 (2 ppm) or filtered air (FA) on PD5 and neurons were counted on PD10, 15, 21, and 28. O3-exposed animals displayed significantly less total neurons on PD21 than FA controls. This study shows that age-related changes in neuron number occur, and that an acute, early postnatal O3 exposure significantly alters sensory neuron development

    Ecosystem Interactions Underlie the Spread of Avian Influenza A Viruses with Pandemic Potential

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    Despite evidence for avian influenza A virus (AIV) transmission between wild and domestic ecosystems, the roles of bird migration and poultry trade in the spread of viruses remain enigmatic. In this study, we integrate ecosystem interactions into a phylogeographic model to assess the contribution of wild and domestic hosts to AIV distribution and persistence. Analysis of globally sampled AIV datasets shows frequent two-way transmission between wild and domestic ecosystems. In general, viral flow from domestic to wild bird populations was restricted to within a geographic region. In contrast, spillover from wild to domestic populations occurred both within and between regions. Wild birds mediated long-distance dispersal at intercontinental scales whereas viral spread among poultry populations was a major driver of regional spread. Viral spread between poultry flocks frequently originated from persistent lineages circulating in regions of intensive poultry production. Our analysis of long-term surveillance data demonstrates that meaningful insights can be inferred from integrating ecosystem into phylogeographic reconstructions that may be consequential for pandemic preparedness and livestock protection.National Institutes of Health (U.S.) (NIH Centers for Excellence in Influenza Research and Surveillance (CEIRS, contract # HHSN266200700010C))National Institutes of Health (U.S.) (NIH Centers for Excellence in Influenza Research and Surveillance (CEIRS, contract # HHSN272201400008C))National Institutes of Health (U.S.) (NIH Centers for Excellence in Influenza Research and Surveillance (CEIRS, contract # HHSN272201400006C)
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