278 research outputs found

    Analytical Investigation of Cycle Characteristics for Advanced Turboelectric Space Power Systems

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    An investigation was made of the relative influence of turbine inlet temperature, radiator temperature, and turbine efficiency on radiator area for Rankine cycles with rubidium, potassium, and sodium as working fluids. It was determined that, whereas turbine inlet temperature and turbine efficiency have gross effects on radiator size for a given inlet temperature a considerable latitude in the selection of radiator temperature may be accepted with only minor effects on required radiator size. Also investigated was the influence on turbine efficiency and design of the factors that distinguish alkali-metal vapor turbines from conventional gas turbines. The turbine configuration was determined to be a function of the involved working fluids and rotor blade speed. For a given blade speed, the number of stages required for high turbine efficiency was found to vary directly with turbine specific work output, and therefore to vary in the ratio 5 to 2.5 to 1 for sodium, potassium, and rubidium, respectively. Lower blade speeds than employed in conventional gas turbines may be required to satisfy critical stress considerations resulting from the elevated temperatures involved and the criterion of long-duration reliability. This will increase the number of turbine stages necessary to obtain high turbine efficiency and consequently increase turbine weight. The question of moisture formation was discussed and a calculation was made to indicate the nature of the aerodynamic losses due to moisture content. Various means of reducing moisture content were considered, including mechanical removal, increased radiator temperature, inefficient expansion, superheat, and reheat. Sample calculations were made in most cases to indicate their comparative effectiveness and resultant penalty in required radiator area

    Beam-Normal Single Spin Asymmetry in Elastic Electron Scattering off 28^{28}Si and 90^{90}Zr

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    We report on a new measurement of the beam-normal single spin asymmetry AnA_{\mathrm{n}} in the elastic scattering of 570 MeV transversely polarized electrons off 28^{28}Si and 90^{90}Zr at Q2=0.04GeV2/c2Q^{2}=0.04\, \mathrm{GeV}^2/c^2. The studied kinematics allow for a comprehensive comparison with former results on 12^{12}C. No significant mass dependence of the beam-normal single spin asymmetry is observed in the mass regime from 12^{12}C to 90^{90}Zr.Comment: Submitted for publication to Physics Letters

    High accuracy synchrotron radiation interferometry with relativistic electrons

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    A high-precision hypernuclear experiment has been performed at the Mainz Microtron (MAMI) to determine the hypertriton {\Lambda} binding energy via decay-pion spectroscopy. A key element of this measurement is an accurate calibration of the magnetic spectrometers with the MAMI beam. For such an absolute calibration with small statistical and systematic uncertainties the undulator light interference method will be applied. In this contribution the basic principle of this method is discussed and the analysis status of the measured synchrotron radiation spectra is presentedComment: The 13th Biennial Conference on Classical and Quantum Relativistic Dynamics of Particles and Fields (IARD22

    Measurement of polarization transfer in the quasi-elastic 40Ca(e,ep)^{40}{\rm Ca}(\vec{e},e' \vec{p}) process

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    Polarization transfer to a bound proton in polarized electron knock-out reactions, A(e,ep)\mathrm{A}(\vec{e},e^{\prime}\vec{p}), is a powerful tool to look for in-medium modification of the bound proton. It requires comparison to calculations which consider the many-body effects accompanying the quasi-free process. We report here measured components PxP_x^{\prime}, PzP_z^{\prime}, and their ratio Px/PzP_x^{\prime}/P_z^{\prime}, of polarization transfer to protons bound in 40Ca^{40}\mathrm{Ca}, which is described well by the shell model and for which reliable calculations are available. While the calculations capture the essence of the data, our statistical precision allows us to observe deviations which cannot be explained by simple scaling, including by varying the proton electromagnetic form factor ratio GE/GMG_E/G_M. We further explore the deviations of the ratio of the polarization transfer components from that of a free proton, (Px/Pz)A/(Px/Pz)H(P_x^{\prime}/P_z^{\prime})_{\rm A}/(P_x^{\prime}/P_z^{\prime})_{\rm H}, and its dependence on the bound-proton virtuality

    ACVIM consensus statement on the diagnosis of immune-mediated hemolytic anemia in dogs and cats

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    Immune-mediated hemolytic anemia (IMHA) is an important cause of morbidity and mortality in dogs. IMHA also occurs in cats, although less commonly. IMHA is considered secondary when it can be attributed to an underlying disease, and as primary (idiopathic) if no cause is found. Eliminating diseases that cause IMHA may attenuate or stop immune-mediated erythrocyte destruction, and adverse consequences of long-term immunosuppressive treatment can be avoided. Infections, cancer, drugs, vaccines, and inflammatory processes may be underlying causes of IMHA. Evidence for these comorbidities has not been systematically evaluated, rendering evidence-based decisions difficult. We identified and extracted data from studies published in the veterinary literature and developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria for IMHA, comorbidities, and causality. Succinct evidence summary statements were written, along with screening recommendations. Statements were refined by conducting 3 iterations of Delphi review with panel and task force members. Commentary was solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted. The resulting document is intended to provide clinical guidelines for diagnosis of, and underlying disease screening for, IMHA in dogs and cats. These should be implemented with consideration of animal, owner, and geographical factors

    High prevalence of chronic kidney disease in Iran: a large population-based study

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    <p>Abstract</p> <p>Background</p> <p>Chronic kidney disease (CKD) is a global public health threat, associated with an alarming increase in morbidity and mortality. The importance is the worldwide increase in its incidence and prevalence.</p> <p>Methods</p> <p>In this cross-sectional study, we estimate the prevalence and determine the associated factors of chronic kidney disease in a representative sample of 10063 participants aged over 20 years, in Tehran, Iran. Chronic kidney disease was defined as estimated glomerular filtration rate less than 60 mL/min/1.73 m2. Glomerular filtration rate was estimated from abbreviated prediction equation provided by the Modification of Diet in Renal Disease study (MDRD).</p> <p>Results</p> <p>Overall prevalence of CKD with the abbreviated MDRD equation was 18.9% (95% confidence interval (CI) 18.2, 20.6). Age adjusted prevalence of CKD was 14.9% (95%CI 14.2, 15.6). Factors associated to CKD include age(years)(odds ratio(OR) 1.1, 95% CI 1.0 to 1.2), female gender (OR 3.1, 95% CI 2.6, 3.7), BMI (BMI 25 to <30 OR 1.5, 95% CI 1.3, 1.8 and BMI ≥ 30 OR 1.6, 95% CI 1.3, 2.0), high waist circumference (OR 1.2, 95% CI 1.1, 1.4), hypertension (OR 1.2, 95% CI 1.1, 1.4), and dyslipidemia (OR 1.3, 95% CI 1.1, 1.5).</p> <p>Conclusion</p> <p>CKD with its high prevalence poses a definite health threat in Iran.</p
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