32 research outputs found

    Reconstruction of annular bi-layered media in cylindrical waveguide section

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    A radial transverse resonance model for two cylindrical concentric layers with different complex dielectric constants is presented. An inverse problem with four unknowns - 3 physical material parameters and one dimensional dielectric layer thickness parameter- is solved by employing TE110 and TE210 modes with different radial field distribution. First a Newton-Raphson algorithm is used to solve a least square problem with a Lorentzian function (as resonance model and "measured" data generator). Then found resonance frequencies and quality factors are used in a second inverse Newton-Raphson algorithm that solves four transverse resonance equations in order to get four unknown parameters. The use of TE110 and TE210 models offers one dimensional radial tomographic capability. An open ended coax quarter-wave resonator is added to the sensor topology, and the effect on the convergence is investigated

    Transverse Momentum Spectra in Au+Au and d+Au Collisions at sNN\sqrt{s_{NN}}=200 GeV and the Pseudorapidity Dependence of High pT_T Suppression

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    We present spectra of charged hadrons from Au+Au and d+Au collisions at sNN=200\sqrt{s_{NN}}=200 GeV measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from p+pˉ{\rm p}+\bar{{\rm p}} collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central Au+Au collisions at η=0\eta=0 and η=2.2\eta=2.2 evidence a strong suppression in the high pTp_{T} region (>>2 GeV/c). In contrast, the d+Au nuclear modification factor (at η=0\eta=0) exhibits an enhancement of the high pTp_T yields. These measurements indicate a high energy loss of the high pTp_T particles in the medium created in the central Au+Au collisions. The lack of suppression in d+Au collisions makes it unlikely that initial state effects can explain the suppression in the central Au+Au collisions.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

    Rapidity Dependence of Charged Antiparticle-to-Particle Ratios in Au+Au Collisions at sNN=200\sqrt{s_{NN}}=200 GeV

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    We present ratios of the numbers of charged antiparticles to particles (pions, kaons and protons) in Au + Au collisions at sNN=200\sqrt{s_{NN}}=200 GeV as a function of rapidity in the range yy=0-3. While the particle ratios at midrapidity are approaching unity, the K/K+K^-/K^+ and pˉ/p\bar{p}/p ratios decrease significantly at forward rapidities. An interpretation of the results within the statistical model indicates a reduction of the baryon chemical potential from μB130\mu_B \approx 130MeV at yy=3 to μB25\mu_B \approx 25MeV at yy=0.Comment: 4 pages, 4 figure

    The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) Study: Protocol for an International Mixed Methods Study

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    BACKGROUND Survivors of childhood cancer represent a growing population with a long life expectancy but high risks of treatment-induced morbidity and premature mortality. Regular physical activity (PA) may improve their long-term health; however, high-quality empirical knowledge is sparse. OBJECTIVE The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) study comprises 4 work packages (WPs) aiming for the objective determination of PA and self-reported health behavior, fatigue, and quality of life (WP 1); physical fitness determination (WP 2); the evaluation of barriers to and facilitators of PA (WP 1 and 3); and the feasibility testing of an intervention to increase PA and physical fitness (WP 4). METHODS The PACCS study will use a mixed methods design, combining patient-reported outcome measures and objective clinical and physiological assessments with qualitative data gathering methods. A total of 500 survivors of childhood cancer aged 9 to 18 years with ≥1 year after treatment completion will be recruited in follow-up care clinics in Norway, Denmark, Finland, Germany, and Switzerland. All participants will participate in WP 1, of which approximately 150, 40, and 30 will be recruited to WP 2, WP3, and WP 4, respectively. The reference material for WP 1 is available from existing studies, whereas WP 2 will recruit healthy controls. PA levels will be measured using ActiGraph accelerometers and self-reports. Validated questionnaires will be used to assess health behaviors, fatigue, and quality of life. Physical fitness will be measured by a cardiopulmonary exercise test, isometric muscle strength tests, and muscle power and endurance tests. Limiting factors will be identified via neurological, pulmonary, and cardiac evaluations and the assessment of body composition and muscle size. Semistructured, qualitative interviews, analyzed using systematic text condensation, will identify the perceived barriers to and facilitators of PA for survivors of childhood cancer. In WP 4, we will evaluate the feasibility of a 6-month personalized PA intervention with the involvement of local structures. RESULTS Ethical approvals have been secured at all participating sites (Norwegian Regional Committee for Medical Research Ethics [2016/953 and 2018/739]; the Oslo University Hospital Data Protection Officer; equivalent institutions in Finland, Denmark [file H-19032270], Germany, and Switzerland [Ethics Committee of Northwestern and Central Switzerland, project ID: 2019-00410]). Data collection for WP 1 to 3 is complete. This will be completed by July 2022 for WP 4. Several publications are already in preparation, and 2 have been published. CONCLUSIONS The PACCS study will generate high-quality knowledge that will contribute to the development of an evidence-based PA intervention for young survivors of childhood cancer to improve their long-term care and health. We will identify physiological, psychological, and social barriers to PA that can be targeted in interventions with immediate benefits for young survivors of childhood cancer in need of rehabilitation. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID) DERR1-10.2196/35838

    Quark Gluon Plasma an Color Glass Condensate at RHIC? The perspective from the BRAHMS experiment

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    We review the main results obtained by the BRAHMS collaboration on the properties of hot and dense hadronic and partonic matter produced in ultrarelativistic heavy ion collisions at RHIC. A particular focus of this paper is to discuss to what extent the results collected so far by BRAHMS, and by the other three experiments at RHIC, can be taken as evidence for the formation of a state of deconfined partonic matter, the so called quark-gluon-plasma (QGP). We also discuss evidence for a possible precursor state to the QGP, i.e. the proposed Color Glass Condensate.Comment: 32 pages, 18 figure

    The acute phase of experimental cardiogenic shock is counteracted by microcirculatory and mitochondrial adaptations

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    The mechanisms contributing to multiorgan dysfunction during cardiogenic shock are poorly understood. Our goal was to characterize the microcirculatory and mitochondrial responses following ≥ 10 hours of severe left ventricular failure and cardiogenic shock. We employed a closed-chest porcine model of cardiogenic shock induced by left coronary microembolization (n = 12) and a time-matched control group (n = 6). Hemodynamics and metabolism were measured hourly by intravascular pressure catheters, thermodilution, arterial and organ specific blood gases. Echocardiography and assessment of the sublingual microcirculation by sidestream darkfield imaging were performed at baseline, 2 ± 1 and 13 ± 3 (mean ± SD) hours after coronary microembolization. Upon hemodynamic decompensation, cardiac, renal and hepatic mitochondria were isolated and evaluated by high-resolution respirometry. Low cardiac output, hypotension, oliguria and severe reductions in mixed-venous and hepatic O2 saturations were evident in cardiogenic shock. The sublingual total and perfused vessel densities were fully preserved throughout the experiments. Cardiac mitochondrial respiration was unaltered, whereas state 2, 3 and 4 respiration of renal and hepatic mitochondria were increased in cardiogenic shock. Mitochondrial viability (RCR; state 3/state 4) and efficiency (ADP/O ratio) were unaffected. Our study demonstrates that the microcirculation is preserved in a porcine model of untreated cardiogenic shock despite vital organ hypoperfusion. Renal and hepatic mitochondrial respiration is upregulated, possibly through demand-related adaptations, and the endogenous shock response is thus compensatory and protective, even after several hours of global hypoperfusion
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