942 research outputs found

    The decay of the observed JPC=1−+J^{PC}=1^{-+} (1400) and JPC=1−+J^{PC}=1^{-+}(1600) hybrid candidates

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    We study the possible interpretation of the two exotic resonances JPC=1−+J^{PC}= 1^{-+} at 1400 and 1600 MeV, claimed to be observed by BNL, decaying respectively into ηπ\eta\pi, ηâ€Čπ\eta'\pi, f1πf_{1}\pi and ρπ\rho\pi. These objects are interpreted as hybrid mesons, in the quark-gluon constituent model using a chromoharmonic confining potentiel. The quantum numbers JPCIG=1−+1−J^{PC}I^{G} = 1^{-+} 1^{-} can be considered in a constituent model as an hybrid meson (qqˉgq \bar q g). The lowest JPC=1−+J^{PC}= 1^{-+}states may be built in two ways : lgl_{g}=1 (gluon-excited) corresponding to an angular momentum between the gluon and (qqˉq \bar q) system, while lqqˉ=1l_{q \bar q}=1 (quarks-excited) corresponds to an angular momentum between qq and qˉ\bar q. For the gluon-excited mode 1−+1^{-+} hybrids, we find the decay dominated by the b1πb_{1}\pi channel, and by the ρπ\rho \pi channel for the quark-excited mode. In our model, neither the quark-excited nor the gluon-excited 1−+1^{-+} (1400 MeV) hybrids can decay into ηπ\eta\pi and ηâ€Čπ\eta'\pi, in contradiction with experiment. Hence, the 1400 MeV resonance seems unlikely to be an hybrid state. The 1−+1^{-+} (1600 MeV) gluon-excited hybrid is predicted with too large a total decay width, to be considered as an hybrid candidate. On the contrary the quark-excited mode has a total decay width around 165 MeV, with a ρπ\rho \pi preferred decay channel, in agreement with BNL. Our conclusion is that {\it{this resonance may be considered as a hybrid meson in the quark-excited mode}}Comment: 13 pages, 1 figur

    COVID-19 and liver disease: mechanistic and clinical perspectives

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    Our understanding of the hepatic consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and its resultant coronavirus disease 2019 (COVID-19) has evolved rapidly since the onset of the pandemic. In this Review, we discuss the hepatotropism of SARS-CoV-2, including the differential expression of viral receptors on liver cell types, and we describe the liver histology features present in patients with COVID-19. We also provide an overview of the pattern and relevance of abnormal liver biochemistry during COVID-19 and present the possible underlying direct and indirect mechanisms for liver injury. Furthermore, large international cohorts have been able to characterize the disease course of COVID-19 in patients with pre-existing chronic liver disease. Patients with cirrhosis have particularly high rates of hepatic decompensation and death following SARS-CoV-2 infection and we outline hypotheses to explain these findings, including the possible role of cirrhosis-associated immune dysfunction. This finding contrasts with outcome data in pharmacologically immunosuppressed patients after liver transplantation who seem to have comparatively better outcomes from COVID-19 than those with advanced liver disease. Finally, we discuss the approach to SARS-CoV-2 vaccination in patients with cirrhosis and after liver transplantation and predict how changes in social behaviours and clinical care pathways during the pandemic might lead to increased liver disease incidence and severity. © 2021, Springer Nature Limited

    WIC Recipients in the Retail Environment: A Qualitative Study Assessing Customer Experience and Satisfaction

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    Background: The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) program is an important intervention for prevention and treatment of obesity and food insecurity, but participation has dropped among eligible populations from 2009 to 2015. Program satisfaction is integral to participant retention, and the retail experience is a vital component of program satisfaction. Objective: This article applies behavioral economics principles to explore the retail experience of WIC participants and ways in which it may be improved. Design: The authors designed and conducted semistructured interviews and focus groups with WIC participants. Participants/setting: A convenience sample of WIC participants aged 18 years and older were recruited through WIC clinics in Texas, North Carolina, Oregon, and Illinois (n=55, 27 participants from four focus groups and 28 individual interviews). Statistical analysis conducted: Responses were analyzed qualitatively using principles of content analysis. Results: Challenges in identifying WIC-allowable items throughout the store as well as perceived stigmatization during the checkout process were the chief complaints. Study participants described a learning curve in successful use of WIC in retail environments over time. Study participants also reported acceptance of restrictions, such as a requirement to purchase the least expensive brand. Conclusions: Dissatisfaction with the retail experience may lead to the underutilization of WIC benefits or program exit. Behavioral economics strategies that facilitate a better shopping experience, such as creating a section for WIC items in the store or improving in-store education, may improve the retail experience for WIC customers. Further research is needed to ensure such strategies are effective and do not contribute to stigma

    Determining risk factors for mortality in liver transplant patients with COVID-19

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    We read with great interest the Correspondence from Bhoori and colleagues1 describing the effect of coronavirus disease 2019 (COVID-19) on their centre's adult liver transplant population.1 Within their cohort of over 150 transplant recipients, the authors identified six patients with COVID-19, including three resulting deaths. Each of those who died was transplanted over 10 years previously and were older than 65 years, male, overweight, and had hypertension and diabetes. The authors speculated as to whether these characteristics might be major risk factors for mortality

    Characterizing Flocculated Mineral Sediments with Acoustic Backscatter, Using Solid and Hybrid Scattering Models

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    This study investigated the performance of an acoustic backscatter system (ABS) for the in situ particle characterization of complex wastes. Two sediments were used: a fine, milled calcite that was flocculated with anionic polyacrylamide and naturally flocculated pond sludge. Particles were initially measured independently by light-based techniques to gain size, the coefficient of variation (COV), and fractal dimensions. For acoustic experiments, a bespoke, high-fidelity ABS was employed with 1, 2.25, and 5 MHz probes and a recirculating mixing tank. Initially, the concentration independent attenuation and backscatter coefficients were measured for each system using a robust calibration procedure at multiple concentrations. Comparisons of the total scattering cross-section (χ) and form function (f) were made between the experimental data and two semiempirical models: a Solid Scattering model and a Hybrid model (where the effects of bound fluid are incorporated). Experimental data compared more closely to the Solid Scattering model, as it was assumed scattering was dominated by small, bound “flocculi” rather than the macroscopic structure. However, if the COV was used as a fit parameter, the hybrid model could give equally accurate fits for a range of input aggregate sizes, highlighting that important size and structure information can be gained from the acoustic models if there is some a priori system data. Additionally, dual-frequency inversions were undertaken to measure concentration profiles for various frequency pairs. Here, the lowest frequency pair gave the best performance (with accurate measurements in the range of 2–35 g·L–1) as interparticle scattering was lowest

    Measurements of Scintillation Efficiency and Pulse-Shape for Low Energy Recoils in Liquid Xenon

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    Results of observations of low energy nuclear and electron recoil events in liquid xenon scintillator detectors are given. The relative scintillation efficiency for nuclear recoils is 0.22 +/- 0.01 in the recoil energy range 40 keV - 70 keV. Under the assumption of a single dominant decay component to the scintillation pulse-shape the log-normal mean parameter T0 of the maximum likelihood estimator of the decay time constant for 6 keV < Eee < 30 keV nuclear recoil events is equal to 21.0 ns +/- 0.5 ns. It is observed that for electron recoils T0 rises slowly with energy, having a value ~ 30 ns at Eee ~ 15 keV. Electron and nuclear recoil pulse-shapes are found to be well fitted by single exponential functions although some evidence is found for a double exponential form for the nuclear recoil pulse-shape.Comment: 11 pages, including 5 encapsulated postscript figure

    Study of the Process e+ e- --> omega pi0 --> pi0 pi0 gamma in c.m. Energy Range 920--1380 MeV at CMD-2

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    The cross section of the process e+ e- --> omega pi0 --> pi0 pi0 gamma has been measured in the c.m. energy range 920-1380 MeV with the CMD-2 detector. Its energy dependence is well described by the interference of the rho(770) and rho'(1450) mesons decaying to omega pi0. Upper limits for the cross sections of the direct processes e+ e- --> pi0 pi0 gamma, eta pi0 gamma have been set.Comment: Accepted for publication in PL

    'Caught Between a Rock and a Hard Place': Anti-discrimination Legislation in the Liberal State and the Fate of the Australian Disability Discrimination Act

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    This article offers a critical analysis of some of the practical implications for disabled people of the Disability Discrimination Act of 1992. Specifically, it raises questions about politics and the role of the law as an instrument of social change?taking greater account of the interests of disabled people?on the one hand, and of the reliance of the social model of disability on a strategy based upon legal rights on the other. The article also suggests that the constraining effects of Australia's constitutional protections of rights and its federal system of government hinder the mildly progressive elements of the Disability Discrimination Act. To illustrate this, the paper employs empirical evidence to suggest that these effects have been exacerbated by the passage of the Human Rights Legislation Amendment Act in 1999

    YREC: The Yale Rotating Stellar Evolution Code

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    The stellar evolution code YREC is outlined with emphasis on its applications to helio- and asteroseismology. The procedure for calculating calibrated solar and stellar models is described. Other features of the code such as a non-local treatment of convective core overshoot, and the implementation of a parametrized description of turbulence in stellar models, are considered in some detail. The code has been extensively used for other astrophysical applications, some of which are briefly mentioned at the end of the paper.Comment: 10 pages, 2 figures, ApSS accepte
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