2,593 research outputs found

    Exploring Lifetime Effects in Femtoscopy

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    We investigate the role of lifetime effects from resonances and emission duration tails in femtoscopy at RHIC in two Blast-Wave models. We find the non-Gaussian components compare well with published source imaged data, but the value of R_out obtained from Gaussian fits is not insensitive to the non-Gaussian contributions when realistic acceptance cuts are applied to models.Comment: 5 pages, 2 figure

    Design and evaluation of fluidized bed heat recovery for diesel engine systems

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    The potential of utilizing fluidized bed heat exchangers in place of conventional counter-flow heat exchangers for heat recovery from adiabatic diesel engine exhaust gas streams was studied. Fluidized bed heat recovery systems were evaluated in three different heavy duty transport applications: (1) heavy duty diesel truck; (2) diesel locomotives; and (3) diesel marine pushboat. The three applications are characterized by differences in overall power output and annual utilization. For each application, the exhaust gas source is a turbocharged-adiabatic diesel core. Representative subposed exhaust gas heat utilization power cycles were selected for conceptual design efforts including design layouts and performance estimates for the fluidized bed heat recovery heat exchangers. The selected power cycles were: organic rankine with RC-1 working fluid, turbocompound power turbine with steam injection, and stirling engine. Fuel economy improvement predictions are used in conjunction with capital cost estimates and fuel price data to determine payback times for the various cases

    Constraining the initial temperature and shear viscosity in a hybrid hydrodynamic model of sNN\sqrt{s_{NN}}=200 GeV Au+Au collisions using pion spectra, elliptic flow, and femtoscopic radii

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    A new framework for evaluating hydrodynamic models of relativistic heavy ion collisions has been developed. This framework, a Comprehesive Heavy Ion Model Evaluation and Reporting Algorithm (CHIMERA) has been implemented by augmenting UVH 2+1D viscous hydrodynamic model with eccentricity fluctuations, pre-equilibrium flow, and the Ultra-relativistic Quantum Molecular Dynamic (UrQMD) hadronic cascade. A range of initial temperatures and shear viscosity to entropy ratios were evaluated for four initial profiles, NpartN_{part} and NcollN_{coll} scaling with and without pre-equilibrium flow. The model results were compared to pion spectra, elliptic flow, and femtoscopic radii from 200 GeV Au+Au collisions for the 0--20% centrality range.Two sets of initial density profiles, NpartN_{part} scaling with pre-equilibrium flow and NcollN_{coll} scaling without were shown to provide a consistent description of all three measurements.Comment: 21 pages, 32 figures, version 3 includes additional text for clarification, division of figures into more manageable units, and placement of chi-squared values in tables for ease of viewin

    Assessing Age Structure, Winter Ticks and Nutritional Condition as Potential Drivers of Fecundity in Montana Moose

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    Fecundity in ungulates is an important component of population dynamics, and itself can be driven by differences in the age and nutritional condition of females.  As one element of a larger research project focused on moose (Alces alces) population dynamics and ecology, we examined nutritional condition, pregnancy rates, and litter sizes for moose in three Montana moose populations.  During the winters of 2013–2015 we captured 100 female moose ? 1 year old and assessed pregnancy status using assays of both serum (pregnancy specific protein B [PSPB]) and feces (fecal progesterone).  After calibrating the relationship between these two assays, we subsequently monitored pregnancy with feces alone for additional winters following capture.  Coincident with captures, animals were aged using tooth extraction and cementum analysis, nutritional condition was assessed using ultrasonography of rump fat thickness, and winter tick loads were estimated by counting ticks along transects of the rump and shoulder.  Additionally, the concentrations of nitrogen and neutral detergent fiber of winter pellets were measured during each winter as indices of dietary quality.  Here, we assess the importance of environmental and demographic factors in limiting moose productivity in Montana by examining the interdependence of forage, parasites, nutritional condition, age structure, and ultimately fecundity for female moose.  We then place these findings in context of fecundity rates observed for moose elsewhere within neighboring US Rocky Mountain populations and across North America

    Calcific Aortic Stenosis A Disease of the Valve and the Myocardium

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    Although aortic stenosis is a common condition associated with major morbidity, mortality, and health economic costs, there are currently no medical interventions capable of delaying or halting its progression. Re-evaluation of the underlying pathophysiology is therefore required so that novel therapeutic strategies can be developed. Aortic stenosis is characterized by progressive aortic valve narrowing and secondary left ventricular hypertrophy. Both processes are important because in combination they drive the development of symptoms and adverse events that characterize the latter stages of the disease. In this review, the authors examine the pathophysiology of aortic stenosis with respect to both the valve and the myocardium. In particular, the authors focus on the role of inflammation, fibrosis, and calcification in progressive valve narrowing and then examine the development of left ventricular hypertrophy, its subsequent decompensation, and the transition to heart failure. Finally the authors discuss potential therapeutic strategies on the basis of similarities aortic stenosis shares with other pathological conditions

    Photoemission evidence for crossover from Peierls-like to Mott-like transition in highly strained VO2_2

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    We present a spectroscopic study that reveals that the metal-insulator transition of strained VO2_2 thin films may be driven towards a purely electronic transition, which does not rely on the Peierls dimerization, by the application of mechanical strain. Comparison with a moderately strained system, which does involve the lattice, demonstrates the crossover from Peierls- to Mott-like transitions

    Maximum entropy deconvolution of resonant inelastic x-ray scattering spectra

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    Resonant inelastic x-ray scattering (RIXS) has become a powerful tool in the study of the electronic structure of condensed matter. Although the linewidths of many RIXS features are narrow, the experimental broadening can often hamper the identification of spectral features. Here, we show that the Maximum Entropy technique can successfully be applied in the deconvolution of RIXS spectra, improving the interpretation of the loss features without a severe increase in the noise ratio
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