A study of the transition from collisional to collisionless plasma flows has been carried out at the National Ignition Facility using high Mach number (M>4) counterstreaming plasmas. In these ...experiments, CD-CD and CD-CH planar foils separated by 6-10 mm are irradiated with laser energies of 250 kJ per foil, generating ∼1000 km/s plasma flows. Varying the foil separation distance scales the ion density and average bulk velocity and, therefore, the ion-ion Coulomb mean free path, at the interaction region at the midplane. The characteristics of the flow interaction have been inferred from the neutrons and protons generated by deuteron-deuteron interactions and by x-ray emission from the hot, interpenetrating, and interacting plasmas. A localized burst of neutrons and bright x-ray emission near the midpoint of the counterstreaming flows was observed, suggesting strong heating and the initial stages of shock formation. As the separation of the CD-CH foils increases we observe enhanced neutron production compared to particle-in-cell simulations that include Coulomb collisions, but do not include collective collisionless plasma instabilities. The observed plasma heating and enhanced neutron production is consistent with the initial stages of collisionless shock formation, mediated by the Weibel filamentation instability.
The remarkable discovery by the Chandra X-ray observatory that the Crab nebula's jet periodically changes direction provides a challenge to our understanding of astrophysical jet dynamics. It has ...been suggested that this phenomenon may be the consequence of magnetic fields and magnetohydrodynamic instabilities, but experimental demonstration in a controlled laboratory environment has remained elusive. Here we report experiments that use high-power lasers to create a plasma jet that can be directly compared with the Crab jet through well-defined physical scaling laws. The jet generates its own embedded toroidal magnetic fields; as it moves, plasma instabilities result in multiple deflections of the propagation direction, mimicking the kink behaviour of the Crab jet. The experiment is modelled with three-dimensional numerical simulations that show exactly how the instability develops and results in changes of direction of the jet.
A central question in the assessment of benefit/harm of new treatments is: how does the average outcome on the new treatment (the factual) compare to the average outcome had patients received no ...treatment or a different treatment known to be effective (the counterfactual)? Randomized controlled trials (RCTs) are the standard for comparing the factual with the counterfactual. Recent developments necessitate and enable a new way of determining the counterfactual for some new medicines. For select situations, we propose a new framework for evidence generation, which we call “threshold‐crossing.” This framework leverages the wealth of information that is becoming available from completed RCTs and from real world data sources. Relying on formalized procedures, information gleaned from these data is used to estimate the counterfactual, enabling efficacy assessment of new drugs. We propose future (research) activities to enable “threshold‐crossing” for carefully selected products and indications in which RCTs are not feasible.
The objectives of this study were to evamine the prevalence of depression in hospitalized, medically ill, older patients with and without congestive heart failure (CHF), and examine correlates, ...course, predictors of outcome, and treatment of depression in patients with CHF. A consecutive sample of 542 patients age 60 or over admitted to inpatient services of Duke University Medical Center were systematically screened by a psychiatrist for depression using the Dignostic Interview Schedule; 342 depressed cases and nondepressed controls were identified. Of these, 107 had a primary or secondary diagnosis of CHF. Among patients with CHF, major depression was identified in 36.5%, a rate that was significantly higher than for patients without CHF (25.5%); the difference was largely explained by low rates of major depression in cardiac patients without CHF (17.0%) who had less severe physical illness. Minor depression was also present in 21.5% of CHF patients, but was not more prevalent than in patients without CHF (17.0%). Compared with nondepressed CHF patients, those with depression were more likely to have comorbid psychiatric disorder, severe medical illness, and severe functional impairment. Depressed patients used more outpatient and inpatients medical services, although this was largely due to the severity of their health problems. Patients often remained depressed for a prolonged period, and over 40% failed to remit during the year following discharge. Factors predicting slower remission included nonhealth-related, stressful life events and low social support; physical health factors at baseline had effect. The majority of depressed CHF patients did not receive treatment for their depression with either antidepressants or psychotherapy, and did not see mental health specialists any more frequently than did the nondepressed. These findings are of concern and have important implications for the diagnosis and treatment of depression in older patients with heart failure.
Abstract Objective Previous research has uncovered relationships between religion/spirituality and depressive disorders. Proposed mechanisms through which religion may impact depression include ...decreased substance use and enhanced social support. Little investigation of these topics has occurred with adolescent psychiatric patients, among whom depression, substance use, and social dysfunction are common. Method 145 subjects, aged 12–18, from two psychiatric outpatient clinics completed the Beck Depression Inventory-II (BDI-II), the Fetzer multidimensional survey of religion/spirituality, and inventories of substance abuse and perceived social support. Measures were completed again six months later. Longitudinal and cross-sectional relationships between depression and religion were examined, controlling for substance abuse and social support. Results Of thirteen religious/spiritual characteristics assessed, nine showed strong cross-sectional relationships to BDI-II score. When perceived social support and substance abuse were controlled for, forgiveness, negative religious support, loss of faith, and negative religious coping retained significant relationships to BDI-II. In longitudinal analyses, loss of faith predicted less improvement in depression scores over 6 months, controlling for depression at study entry. Limitations Self-report data, clinical sample. Conclusions Several aspects of religiousness/spirituality appear to relate cross-sectionally to depressive symptoms in adolescent psychiatric patients. Findings suggest that perceived social support and substance abuse account for some of these correlations but do not explain relationships to negative religious coping, loss of faith, or forgiveness. Endorsing a loss of faith may be a marker of poor prognosis among depressed youth.
Monoenergetic-proton radiographs of laser-generated, high-Mach-number plasma jets colliding at various angles shed light on the structures and dynamics of these collisions. The observations compare ...favorably with results from 2D hydrodynamic simulations of multistream plasma jets, and also with results from an analytic treatment of electron flow and magnetic field advection. In collisions of two noncollinear jets, the observed flow structure is similar to the analytic model's prediction of a characteristic feature with a narrow structure pointing in one direction and a much thicker one pointing in the opposite direction. Spontaneous magnetic fields, largely azimuthal around the colliding jets and generated by the well-known ∇T(e)×∇n(e) Biermann battery effect near the periphery of the laser spots, are demonstrated to be "frozen in" the plasma (due to high magnetic Reynolds number Re(M)∼5×10(4)) and advected along the jet streamlines of the electron flow. These studies provide novel insight into the interactions and dynamics of colliding plasma jets.
A detailed understanding of surface defects is highly desirable, e.g. to clarify their role as active sites in catalysis. Here localized defects on the surface of MgO films deposited on Ag(001) are ...investigated. Since the electronic structure of color centers depends on their local position, spectroscopic signals are highly convoluted and often difficult to disentangle. In this study we aimed to obtain morphological and spectroscopic information on single color centers at a microscopic level with frequency modulated dynamic force microscopy (FM-DFM) and scanning tunneling microscopy (STM) in an ultrahigh vacuum and at low temperature. Four of the major and in literature mostly discussed defect types on MgO have been characterized by their charge state and finally identified by the complementary application of FM-DFM and STM in combination with density functional theory results.
The synthesis and antiproliferative activity of Mes- and iPr-substituted gold(I) bis(1,2,3-triazol-5-ylidene) complexes in various cancer cell lines are reported, showing nanomolar IC50 values of ...50 nM (lymphoma cells) and 500 nM (leukemia cells), respectively (Mes < iPr). The compounds exclusively induce apoptosis (50 nM to 5 μM) instead of necrosis in common malignant blood cells (leukemia cells) and do not affect non-malignant leucocytes. Remarkably, the complexes not only overcome resistances against the well-established cytostatic etoposide, cytarabine, daunorubicin, and cisplatin but also promote a synergistic effect of up to 182% when used with daunorubicin. The present results demonstrate that gold(I) bis(1,2,3-triazol-5-ylidene) complexes are highly promising and easily modifiable anticancer metallodrugs.
In patients suffering from cerebrovascular diseases and traumatic brain damage, increases in serum levels of protein S100B are positively correlated with the severity of the insult. Since high ...concentrations of S100B have been shown to exert neurotoxic effects, the objective of this study was to characterize the regulatory mechanisms underlying control of S100B release from astrocytes. To that end, we analyzed the kinetics and amount of S100B release in correlation with regulation of S100B gene expression in an in vitro ischemia model. Astrocyte cultures were treated with combined oxygen, serum and glucose deprivation, serum and glucose deprivation or hypoxia alone for 6, 12 and 24 h, respectively. While oxygen, serum and glucose deprivation triggered the most rapid release of S100B, serum and glucose deprivation provoked comparable levels of released S100B at the later time points. In contrast to oxygen, serum and glucose deprivation and serum and glucose deprivation, hypoxia alone elicited only marginal increases in secreted S100B. Parallel analysis of extracellular lactate dehydrogenase and the number of viable cells revealed only moderate cell death in the cultures, indicating that S100B was actively secreted during in vitro ischemia. Interestingly, S100B mRNA expression was potently downregulated after 12 and 24 h of oxygen, serum and glucose deprivation, and prolonged oxygen, serum and glucose deprivation for 48 h was associated with a significant reduction of S100B release at later time intervals, whereas lactate dehydrogenase levels remained constant. Our data suggest that secretion of S100B during the glial response to metabolic injury is an early and active process.
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