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Magnetized plasma interactions are ubiquitous in astrophysical and laboratory plasmas. Various physical effects have been shown to be important within colliding plasma flows influenced by opposing magnetic fields, however, experimental verification of the mechanisms within the interaction region has remained elusive. Here we discuss a laser-plasma experiment whereby experimental results verify that Biermann battery generated magnetic fields are advected by Nernst flows and anisotropic pressure effects dominate these flows in a reconnection region. These fields are mapped using time-resolved proton probing in multiple directions. Various experimental, modelling and analytical techniques demonstrate the importance of anisotropic pressure in semi-collisional, high-ß plasmas, causing a reduction in the magnitude of the reconnecting fields when compared to resistive processes. Anisotropic pressure dynamics are crucial in collisionless plasmas, but are often neglected in collisional plasmas. We show pressure anisotropy to be essential in maintaining the interaction layer, redistributing magnetic fields even for semi-collisional, high energy density physics (HEDP) regimes.
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Shocks are abundant both in astrophysical and laboratory systems. While the electric fields generated at shock fronts have recently attracted great attention, the associated self-generated magnetic field is rarely studied, despite its ability to significantly affect the shock profile in the nonideal geometry where density and temperature gradients are not parallel. We report here the observation of a magnetic field at the front of a Mach â¼6 shock propagating in a low-density helium gas system. Proton radiography from different projection angles not only confirms the magnetic field's existence, but also provides a quantitative measurement of the field strength in the range â¼5 to 7 T. X-ray spectrometry allowed inference of the density and temperature at the shock front, constraining the plasma conditions under which the magnetic and electric fields are generated. Simulations with the particle-in-cell code lsp attribute the self-generation of the magnetic field to the Biermann battery effect (∇n_{e}×∇T_{e}).
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We present a design for a pixelated scintillator based gamma-ray spectrometer for non-linear inverse Compton scattering experiments. By colliding a laser wakefield accelerated electron beam with a tightly focused, intense laser pulse, gamma-ray photons up to 100 MeV energies and with few femtosecond duration may be produced. To measure the energy spectrum and angular distribution, a 33 × 47 array of cesium-iodide crystals was oriented such that the 47 crystal length axis was parallel to the gamma-ray beam and the 33 crystal length axis was oriented in the vertical direction. Using an iterative deconvolution method similar to the YOGI code, modeling of the scintillator response using GEANT4 and fitting to a quantum Monte Carlo calculated photon spectrum, we are able to extract the gamma ray spectra generated by the inverse Compton interaction.
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We present nanosecond time-scale Vlasov-Fokker-Planck-Maxwell modeling of magnetized plasma transport and dynamics in a hohlraum with an applied external magnetic field, under conditions similar to recent experiments. Self-consistent modeling of the kinetic electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's law, including Nernst advection of magnetic fields. In addition to showing the prevalence of nonlocal behavior, we demonstrate that effects such as anomalous heat flow are induced by inverse bremsstrahlung heating. We show magnetic field amplification up to a factor of 3 from Nernst compression into the hohlraum wall. The magnetic field is also expelled towards the hohlraum axis due to Nernst advection faster than frozen-in flux would suggest. Nonlocality contributes to the heat flow towards the hohlraum axis and results in an augmented Nernst advection mechanism that is included self-consistently through kinetic modeling.
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In the interaction of high-power laser beams with solid density plasma there are a number of mechanisms that generate strong magnetic fields. Such fields subsequently inhibit or redirect electron flows, but can themselves be advected by heat fluxes, resulting in complex interplay between thermal transport and magnetic fields. We show that for heating by multiple laser spots reconnection of magnetic field lines can occur, mediated by these heat fluxes, using a fully implicit 2D Vlasov-Fokker-Planck code. Under such conditions, the reconnection rate is dictated by heat flows rather than Alfvènic flows. We find that this mechanism is only relevant in a high ß plasma. However, the Hall parameter ωcτei can be large so that thermal transport is strongly modified by these magnetic fields, which can impact longer time scale temperature homogeneity and ion dynamics in the system.
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BACKGROUND: In India, most people adhere to a vegetarian diet, which may lead to cobalamin deficiency. OBJECTIVE: The objective was to examine indicators of cobalamin status in Asian Indians. DESIGN: The study population included 204 men and women aged 27-55 y from Pune, Maharashtra, India, categorized into 4 groups: patients with cardiovascular disease (CVD) and diabetes, patients with CVD but no diabetes, patients with diabetes but no CVD, and healthy subjects. Data on medical history, lifestyle, and diet were obtained by interviews and questionnaires. Blood samples were collected for measurement of serum or plasma total cobalamin, holotranscobalamin (holoTC), methylmalonic acid (MMA), and total homocysteine (tHcy) and hemetologic indexes. RESULTS: MMA, tHcy, total cobalamin, and holoTC did not differ significantly among the 4 groups; therefore, the data were pooled. Total cobalamin showed a strong inverse correlation with tHcy (r = -0.59) and MMA (r = -0.54). Forty-seven percent of the subjects had cobalamin deficiency (total cobalamin <150 pmol/L), 73% had low holoTC (<35 pmol/L), 77% had hyperhomocysteinemia (tHcy >15 micromol/L), and 73% had elevated serum MMA (>0.26 micromol/L). These indicators of impaired cobalamin status were observed in both vegetarians and nonvegetarians. Folate deficiency was rare and only 2.5% of the subjects were homozygous for the MTHFR 677C-->T polymorphism. CONCLUSIONS: About 75% of the subjects had metabolic signs of cobalamin deficiency, which was only partly explained by the vegetarian diet. If impaired cobalamin status is confirmed in other parts of India, it may have important health implications.
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Homocisteína/sangre , Hiperhomocisteinemia/sangre , Ácido Metilmalónico/sangre , Deficiencia de Vitamina B 12/diagnóstico , Vitamina B 12/sangre , Adulto , Biomarcadores , Enfermedades Cardiovasculares/sangre , Enfermedades Cardiovasculares/fisiopatología , Diabetes Mellitus/sangre , Diabetes Mellitus/fisiopatología , Dieta Vegetariana , Femenino , Ácido Fólico/sangre , Humanos , India/epidemiología , Masculino , Persona de Mediana Edad , Prevalencia , Encuestas y Cuestionarios , Deficiencia de Vitamina B 12/sangre , Deficiencia de Vitamina B 12/epidemiologíaRESUMEN
SNAP receptor (SNARE) complexes bridge opposing membranes to promote membrane fusion within the secretory and endosomal pathways. Because only the exocytic SNARE complexes have been characterized in detail, the structural features shared by SNARE complexes from different fusion steps are not known. We now describe the subunit structure, assembly, and regulation of a quaternary SNARE complex, which appears to mediate an early step in endoplasmic reticulum (ER) to Golgi transport. Purified recombinant syntaxin 5, membrin, and rbet1, three Q-SNAREs, assemble cooperatively to create a high affinity binding site for sec22b, an R-SNARE. The syntaxin 5 amino-terminal domain potently inhibits SNARE complex assembly. The ER/Golgi quaternary complex is remarkably similar to the synaptic complex, suggesting that a common pattern is followed at all transport steps, where three Q-helices assemble to form a high affinity binding site for a fourth R-helix on an opposing membrane. Interestingly, although sec22b binds to the combination of syntaxin 5, membrin, and rbet1, it can only bind if it is present while the others assemble; sec22b cannot bind to a pre-assembled ternary complex of syntaxin 5, membrin, and rbet1. Finally, we demonstrate that the quaternary complex containing sec22b is not an in vitro entity only, but is a bona fide species in living cells.
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Retículo Endoplásmico/química , Proteínas de la Membrana/química , Proteínas de Transporte Vesicular , Animales , Sitios de Unión , Unión Competitiva , Línea Celular , Membrana Celular/metabolismo , Cromatografía , Relación Dosis-Respuesta a Droga , Escherichia coli/metabolismo , Glutatión Transferasa/metabolismo , Aparato de Golgi/química , Humanos , Cinética , Proteínas de la Membrana/metabolismo , Modelos Biológicos , Pruebas de Precipitina , Unión Proteica , Conformación Proteica , Estructura Terciaria de Proteína , Proteínas Qa-SNARE , Proteínas Qb-SNARE , Proteínas Qc-SNARE , Ratas , Proteínas Recombinantes de Fusión/metabolismo , Proteínas SNARE , TransfecciónRESUMEN
UNLABELLED: A lot of research has pointed to a complex interaction between stressful life events, psychiatric morbidity and the irritable bowel syndrome (IBS). AIM: The present study aimed to determine the: stressful life-events in patients with irritable bowel syndrome patients in comparison to normal controls; effect of these events in causing clinically significant anxiety and depression; and the effect of psychopathology i.e. anxiety and depression on coping skills in these patients. METHODOLOGY: Thirty patients with irritable bowel syndrome were compared with thirty matched normal controls, on the presumptive stressful life events scale and the mechanisms of coping scale. Further, among the irritable bowel syndrome patient group, the anxious and depressed subgroups were separated from the non-anxious and non-depressed subgroups using the hospital anxiety and depression scale. Positive and negative coping mechanisms between these subgroups were compared. RESULTS: Significantly higher stress scores were found in the irritable bowel syndrome patient group than normal controls. Not all, but slightly more than fifty percent of irritable bowel syndrome had definite and clinically significant anxiety and/or depression. Those IBS patients with either definite depression tended to use predominantly negative coping styles as compared to those IBS patients without anxiety or depression. CONCLUSION: Stressful life-event scores are significantly higher in IBS patients than in normal controls. Although not all of these patients have anxiety and/or depression, a significant number of patients show evidence of the same. Presence or absence of anxiety and/or depression influences how the patient with IBS copes with illness. Therefore, though further studies on the issue are required, we suggested that, as a supplement to medical management, recognition and treatment of anxiety and depression in this subgroup of IBS patients with psychotropic drugs and cognitive therapy for gaining more positive coping skills, may require special attention in the management of irritable bowel syndrome.
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Adaptación Psicológica , Ansiedad/psicología , Enfermedades Funcionales del Colon/psicología , Depresión/psicología , Acontecimientos que Cambian la Vida , Trastornos Psicofisiológicos/psicología , Adulto , Femenino , Humanos , Masculino , Determinación de la Personalidad , Rol del EnfermoRESUMEN
AIMS: A study was designed to assess the effects of a standardized instructional videotape on training senior medical students to acceptable levels of reliability in performing several commonly used obsever dependent outcome measures in patients with ankylosing spondylilis (AS). METHODS: During a single day, six third-year medical students independently examined five patients with AvS in predetermined order using a Latin Square design, before and after viewing a standardized videotape demonstrating 14 examination techniques. Reliability coefficients were calculated based on the variance components of the analysis of variance (ANOVA) table. RESULTS: Prestandardization reliability coefficients were < 0.80 for three measures. Following standardization 12 reliability coefficients exceeded 0.80. For the majority of measures prestandardization reliability coefficients were high and no further improvement in reliability could be demonstrated. CONCLUSIONS: High levels of interobserver agreement were noted prior to viewing the instructional videotape. This may represent the success of undergraduate clinical skills training programmes, or it may be the result of having reviewed an illustrated instructional text just prior to the initial patient examinations. With the exception of chest excursion, high levels of prestandardization reliability, by necessity, precluded the demonstration of significant effects from viewing the videotape. Nevertheless, the data indicate that senior medical students arc capable of reliably performing quantitative measurement in AS. Recent surveys in Canada and Australia, showing a general lack of quantitative clinical measurement in the longitudinal follow up of AS outpatients by rheumatologists, suggest that the lack of quantitation is not due to inability to reliably perform the measurements.
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Poor insight in schizophrenia has been recently thought to be a reflection of prominent and enduring neurocognitive impairments. Reports supporting this theory have implicated prefrontal and parietal lobe functions, among other parameters. The results of other studies have negated the role of neuropsychological abnormalities in poor insight. The analogy between poor insight in schizophrenia and anosognosia in neurological illness as proposed by one set of workers has been elucidated in this review and it appears quite promising. However, the drawing of definite conclusions from all this work has been deferred by us, because of the need for more uniform and standardized methodologies for research on the subject. Nevertheless, attempts to improve the cognitive processes, which affect insight in schizophrenia, may be done to gain better treatment outcome in this disorder.
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Concienciación , Esquizofrenia , Psicología del Esquizofrénico , Cognición , Terapia Cognitivo-Conductual , Negación en Psicología , Humanos , Esquizofrenia/terapiaRESUMEN
In search of hypercellulolytic microorganisms, ultraviolet irradiation carried out with Penicillium funiculosum has yielded a superior mutant. The investigations reported in this article are shake flask studies on some important nutritional requirements of the mutant, namely, nitrogen source, carbon source, and inducers. The mutant shows an ability to metabolize inorganic nitrogen sources like urea and sodium nitrate both for growth and enzyme production. A comparison of the long-term saccharification ability and the utilization efficiency of the mutant enzyme with those reported in the literature is also carried out, showing the superior performance of the mutant enzyme.
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Munchausen's syndrome is a chronic condition in which patients with factitious illness present with dramatic and sometimes self-inflicted signs and symptoms. Much investigation is needed to delineate the etiology and psychodynamics of this disorder. After other causes for the patient's condition have been ruled out and a firm diagnosis is made, cautious confrontation with long-term psychotherapy, if the patient is amenable, is thought to be the best approach.