559 research outputs found

    Application of pactiter V3.3 code to the ACPS assessment of ITER neutral beam injectors primary heat transfer system

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    Activated Corrosion Products (ACPs) will be present in the various coolant loops of ITER: in-vessel and vacuum vessel, test blanket modules, auxiliary heating or diagnostic equipments. ACPs impact occupational exposure, routine effluents to the environment, and potential releases during accidents. Hence, the ACP inventory evaluation is an important task for ITER public and occupational safety. PACTITER v3.3 code is a computational tool derived from PACTOLE series of codes, modified in some modeling and computing capabilities. ITER Organization has included it as reference computer code for the ACP assessment. In the framework of its verification and validation activity, PACTITER v3.3 was used to assess the ACP inventory of the ITER Neutral Beam Injectors (NBIs) Primary Heat Transfer System (PHTS). This paper will document the preliminary results of this assessment, focusing on the impact of operation scenarios parameters (i.e. water chemistry, materials corrosion properties, etc.) and piping architecture

    Nonlinear diffusion & thermo-electric coupling in a two-variable model of cardiac action potential

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    This work reports the results of the theoretical investigation of nonlinear dynamics and spiral wave breakup in a generalized two-variable model of cardiac action potential accounting for thermo-electric coupling and diffusion nonlinearities. As customary in excitable media, the common Q10 and Moore factors are used to describe thermo-electric feedback in a 10-degrees range. Motivated by the porous nature of the cardiac tissue, in this study we also propose a nonlinear Fickian flux formulated by Taylor expanding the voltage dependent diffusion coefficient up to quadratic terms. A fine tuning of the diffusive parameters is performed a priori to match the conduction velocity of the equivalent cable model. The resulting combined effects are then studied by numerically simulating different stimulation protocols on a one-dimensional cable. Model features are compared in terms of action potential morphology, restitution curves, frequency spectra and spatio-temporal phase differences. Two-dimensional long-run simulations are finally performed to characterize spiral breakup during sustained fibrillation at different thermal states. Temperature and nonlinear diffusion effects are found to impact the repolarization phase of the action potential wave with non-monotone patterns and to increase the propensity of arrhythmogenesis

    Charge density waves enhance the electronic noise of manganites

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    The transport and noise properties of Pr_{0.7}Ca_{0.3}MnO_{3} epitaxial thin films in the temperature range from room temperature to 160 K are reported. It is shown that both the broadband 1/f noise properties and the dependence of resistance on electric field are consistent with the idea of a collective electrical transport, as in the classical model of sliding charge density waves. On the other hand, the observations cannot be reconciled with standard models of charge ordering and charge melting. Methodologically, it is proposed to consider noise-spectra analysis as a unique tool for the identification of the transport mechanism in such highly correlated systems. On the basis of the results, the electrical transport is envisaged as one of the most effective ways to understand the nature of the insulating, charge-modulated ground states in manganites.Comment: 6 two-column pages, 5 figure

    The FDA “black box” warning on antidepressant suicide risk in young adults: More harm than benefits?

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    The decision made in the year 2004 by the U.S. Food and Drug Administration (FDA) to require a boxed warning on antidepressants regarding the risk of suicidality in young adults still represents a matter of controversy. The FDA warning was grounded on industry-sponsored trials carried one decade ago or earlier. However, within the past decade, an increasing number of reports have questioned the actual validity of the FDA warning, especially considering a decline in the prescription of the antidepressant drugs associated with an increase in the rate of suicidal events among people with severe depression. The present report provides an overview of the FDA black box warning, also documenting two Major Depressive Disorder patients whose refusal to undergo a pharmacological antidepressant treatment possibly led to an increased risk for suicidal behaviors. The concerns raised by the FDA black box warning need to be considered in real-world clinical practice, stating the associated clinical and public health implications

    Polar catastrophe and electronic reconstructions at the LaAlO3/SrTiO3 interface: evidence from optical second harmonic generation

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    The so-called "polar catastrophe", a sudden electronic reconstruction taking place to compensate for the interfacial ionic polar discontinuity, is currently considered as a likely factor to explain the surprising conductivity of the interface between the insulators LaAlO3 and SrTiO3. We applied optical second harmonic generation, a technique that a priori can detect both mobile and localized interfacial electrons, to investigating the electronic polar reconstructions taking place at the interface. As the LaAlO3 film thickness is increased, we identify two abrupt electronic rearrangements: the first takes place at a thickness of 3 unit cells, in the insulating state; the second occurs at a thickness of 4-6 unit cells, i.e., just above the threshold for which the samples become conducting. Two possible physical scenarios behind these observations are proposed. The first is based on an electronic transfer into localized electronic states at the interface that acts as a precursor of the conductivity onset. In the second scenario, the signal variations are attributed to the strong ionic relaxations taking place in the LaAlO3 layer

    Correlation between choriocapillaris density and retinal sensitivity in age-related macular degeneration

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    Purpose: The purpose of this study was to investigate the relationship between perfusion of the choriocapillaris (CC) and retinal sensitivity in eyes with intermediate agerelated macular degeneration (iAMD). Methods: This prospective study included patients with iAMD and healthy controls. All enrolled subjects underwent optical coherence tomography angiography (OCT-A) in order to compute the percent perfused choriocapillaris area (PPCA). In patients with iAMD, microperimetry (MP) testing was performed in order to quantify: mean retinal sensitivity (MRS), over an area of 10 degrees; mean macular sensitivity (MMS), over the macular area scanned with OCT-A; and retinal sensitivity (RS) in each macular point. Results: Eighteen eyes of 13 patients were included in the analysis. In addition, 18 eyes of 12 healthy subjects were enrolled as controls. No statistically significant difference (P value > 0.2) was observed in age between patients (73.9 ± 2.0 years) and controls (70.1 ± 2.8 years). We observed significantly lower values of PPCA between patients with iAMD and healthy controls (42.0% ± 3.8% vs. 66.4% ± 3.0%; -Β = 23.8%; P value < 0.001). Among iAMD eyes, higher values of PPCA were significantly associated with higher values of MRS (P value=0.002) and MMS (P value=0.013). Finally, higher values of RS in eachmacular point analyzedwithMPwere significantly (P value<0.001) associated with higher values of PPCA computed in circular regions of interest (ROIs) centered in each analyzed MP point with radii of 0.5 degrees and 1.0 degree. Conclusions: Using OCT-A, we demonstrated a significant association between CC impairment and macular dysfunction, quantified by MP, in iAMD eyes. Translational Relevance: OCT-A could be a useful tool for detecting CC alterations and to monitor disease progression

    Inflammatory markers and suicidal attempts in depressed patients: A review

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    Major depressive disorder is a chronic and invalidating psychiatric illness and is associated with a greater risk of suicidal behaviors. In recent decades many data have supported a biological link between depressive states and inflammation. Pro-inflammatory cytokines have been found to rise, first of all TNF-α and IL-6. Suicidal behaviors have been consistently associated with increased levels of IL-6 and decreased levels of IL-2. The aim of this review is to investigate the relationship between inflammatory markers in depressed patients with or without suicidal attempts compared to healthy controls

    A flash in the dark: UVES/VLT high resolution spectroscopy of GRB afterglows

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    We present the first high resolution (R=20000--45000, corresponding to 14 km/s at 4200A to 6.6 km/s at 9000A) observations of the optical afterglow of Gamma Ray Bursts. GRB020813 and GRB021004 were observed by UVES@VLT 22.19 hours and 13.52 hours after the trigger, respectively. These spectra show that the inter--stellar matter of the GRB host galaxies is complex, with many components contributing to each main absorption system, and spanning a total velocity range of up to about 3000 km/s. Several narrow components are resolved down to a width of a few tens of km/s. In the case of GRB021004 we detected both low and high ionization lines. Combined with photoionization results obtained with CLOUDY, the ionization parameters of the various systems are consistent with a remarkably narrow range with no clear trend with system velocity. This can be interpreted as due to density fluctuations on top of a regular R^-2 wind density profile.Comment: Most figure improved, a few typos corrected, added a new subsection. ApJ in pres
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