212 research outputs found
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Antiproton fast ignition for Inertial Confinement Fusion
With 180MJ/{micro}g, antiprotons offer the highest stored energy per unit mass of any known entity. We investigate the use of antiprotons to promote fast ignition in an ICF capsule and seek high gains with only modest compression of the main fuel. Unlike standard fast ignition where the ignition energy is supplied by an energetic, short pulse laser, the energy here is supplied through the ionization energy deposited when antiprotons annihilate at the center of a compressed fuel capsule. In the first of two candidate fast ignition schemes, the antiproton package is delivered by a low energy external ion beam. In the second, ''autocatalytic'' scheme, the antiprotons are pre-emplaced at the center of the capsule prior to compression. In both schemes, we estimate that {approximately}3x10{sup 13} antiprotons are required to initiate fast ignition in a typical ICF capsule and show that incorporation of a thin, heavy metal shell is desirable to enhance energy deposition in the igniter zone. In addition to obviating the need for a second energetic fast laser and vulnerable final optics, this scheme would achieve central without reliance on laser channeling through halo plasma or houlrahm debris. However, in addition to the unknowns involved in the storage and manipulation of antiprotons at low energy, the other large uncertainty for the practicality of such a scheme is the ultimate efficiency of antiproton production in, an external, optimized facility
Prospective evaluation of quality of life after conventional abdominal aortic aneurysm surgery
Objectives:To evaluate the changes in quality of life following conventional abdominal aortic aneurysm repair.Design:Prospective study.Materials and methods:Fifty-nine consecutive patients (50 men; nine women) in two surgical centres were investigated preoperatively, and at 6 weeks, 3 months and 6 months postoperatively. Quality of life was measured using the Short Form 36 (SF 36) questionnaire and the York Quality of Life questionnaire, from which the Rosser index was calculated.Results:Rosser index assessment showed restoration of quality of life to preoperative levels by 3 months, and significant improvement at 6 months. Changes in the SF 36 revealed significant improvement in mental health, and physical role limitation at all times postoperatively. Social function worsened at 6 weeks but improved to preoperative levels by 3 and 6 months after surgery.Conclusions:Quality of life was improved after open aortic aneurysm repair. The time course of recovery shows a predominant improvement between 6 weeks and 3 months postoperatively
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Direct Drive Heavy-Ion-Beam Inertial Fusion at High Coupling Efficiency
Issues with coupling efficiency, beam illumination symmetry and Rayleigh Taylor (RT) instability are discussed for spherical heavy-ion-beam-driven targets with and without hohlraums. Efficient coupling of heavy ion beams to compress direct-drive inertial fusion targets without hohlraums is found to require ion range increasing several-fold during the drive pulse. One-dimensional implosion calculations using the LASNEX ICF target physics code shows the ion range increasing four-fold during the drive pulse to keep ion energy deposition following closely behind the imploding ablation front, resulting in high coupling efficiencies (shell kinetic energy/incident beam energy of 16 to 18%). Ways to increase beam ion range while mitigating Rayleigh-Taylor instabilities are discussed for future work
MHV-Vertices for Gravity Amplitudes
We obtain a CSW-style formalism for calculating graviton scattering
amplitudes and prove its validity through the use of a special type of
BCFW-like parameter shift. The procedure is illustrated with explicit examples.Comment: 21 pages, minor typos corrected, proof added in section
Latent class cluster analysis of symptom ratings identifies distinct subgroups within the clinical high risk for psychosis syndrome
© 2017 The clinical-high-risk for psychosis (CHR-P) syndrome is heterogeneous in terms of clinical presentation and outcomes. Identifying more homogenous subtypes of the syndrome may help clarify its etiology and improve the prediction of psychotic illness. This study applied latent class cluster analysis (LCCA) to symptom ratings from the North American Prodrome Longitudinal Studies 1 and 2 (NAPLS 1 and 2). These analyses produced evidence for three to five subgroups within the CHR-P syndrome. Differences in negative and disorganized symptoms distinguished among the subgroups. Subgroup membership was found to predict conversion to psychosis. The authors contrast the methods employed within this study with previous attempts to identify more homogenous subgroups of CHR-P individuals and discuss how these results could be tested in future samples of CHR-P individuals
One-Loop NMHV Amplitudes involving Gluinos and Scalars in N=4 Gauge Theory
We use Supersymmetric Ward Identities and quadruple cuts to generate n-pt
NMHV amplitudes involving gluinos and adjoint scalars from purely gluonic
amplitudes. We present a set of factors that can be used to generate one-loop
NMHV amplitudes involving gluinos or adjoint scalars in N=4 Super Yang-Mills
from the corresponding purely gluonic amplitude.Comment: 16 pages, JHEP versio
Networks of blood proteins in the neuroimmunology of schizophrenia.
Levels of certain circulating cytokines and related immune system molecules are consistently altered in schizophrenia and related disorders. In addition to absolute analyte levels, we sought analytes in correlation networks that could be prognostic. We analyzed baseline blood plasma samples with a Luminex platform from 72 subjects meeting criteria for a psychosis clinical high-risk syndrome; 32 subjects converted to a diagnosis of psychotic disorder within two years while 40 other subjects did not. Another comparison group included 35 unaffected subjects. Assays of 141 analytes passed early quality control. We then used an unweighted co-expression network analysis to identify highly correlated modules in each group. Overall, there was a striking loss of network complexity going from unaffected subjects to nonconverters and thence to converters (applying standard, graph-theoretic metrics). Graph differences were largely driven by proteins regulating tissue remodeling (e.g. blood-brain barrier). In more detail, certain sets of antithetical proteins were highly correlated in unaffected subjects (e.g. SERPINE1 vs MMP9), as expected in homeostasis. However, for particular protein pairs this trend was reversed in converters (e.g. SERPINE1 vs TIMP1, being synthetical inhibitors of remodeling of extracellular matrix and vasculature). Thus, some correlation signals strongly predict impending conversion to a psychotic disorder and directly suggest pharmaceutical targets
Common Data Elements for National Institute of Mental Health–Funded Translational Early Psychosis Research
The National Institutes of Health has established the PhenX Toolkit as a web-based resource containing consensus measures freely available to the research community. The National Institute of Mental Health (NIMH) has introduced the Mental Health Research Core Collection as part of the PhenX Toolkit and recently convened the PhenX Early Psychosis Working Group to generate the PhenX Early Psychosis Specialty Collection. The Working Group consisted of two complementary panels for clinical and translational research. We review the process, deliberations, and products of the translational research panel. The Early Psychosis Specialty Collection rationale for measure selection as well as additional information and protocols for obtaining each measure are available on the PhenX website (https://www.phenxtoolkit.org). The NIMH strongly encourages investigators to use instruments from the PhenX Mental Health Research Collections in NIMH-funded studies and discourages use of alternative measures to collect similar data without justification. We also discuss some of the potential advances that can be achieved by collecting common data elements across large-scale longitudinal studies of early psychosis
Psychotropic medication use in youth at high risk for psychosis: Comparison of baseline data from two research cohorts 1998-2005 and 2008-2011
Background: Antipsychotic medication use rates have generally been rising among youth with psychiatric disorders, but little is known about use rates of antipsychotics or other psychotropic medications in patients at high risk for psychosis. Method: Baseline psychotropic medication use rates were compared in two research cohorts of patients at high risk for psychosis that enrolled between 1998-2005 (n. = 391) and 2008-2011 (n. = 346). Treatment durations and antipsychotic doses were described for cohort 2. Results: Median age was 17. years in cohort 1 and 18. years in cohort 2. The rate of prescription of any psychotropic at baseline was roughly 40% for each cohort. Antipsychotic prescription rates were 24% among sites that permitted baseline antipsychotic use in cohort 1 and 18% in the cohort 2; the decline did not quite reach statistical significance (p. = 0.064). In cohort 2 the mean. ±. SD baseline chlorpromazine-equivalent dose was 121. ±. 108. mg/d, and lifetime duration of antipsychotic treatment was 3.8. ±. 5.9. months. Discussion: Although the rate of antipsychotic prescription among high-risk youth may have fallen slightly, the nearly one-in-five rate in the second cohort still constitutes a significant exposure. Mitigating factors were that doses and durations of treatment were low. As for other nonpsychotic conditions, it is incumbent on our field to develop alternative treatments for high-risk patients and to generate additional evidence for or against the efficacy of antipsychotics to help define their appropriate role if alternative treatments fail
Characterizing Covariant Trajectories of Individuals at Clinical High Risk for Psychosis across Symptomatic and Functional Domains
Objective: The authors sought to characterize differences in outcomes among help-seeking individuals at clinical high risk for psychosis by identifying covariant longitudinal patterns of symptoms and functioning. Methods: Group-based multitrajectory modeling was applied to longitudinal ratings of four symptom domains (positive, negative, disorganized, general) and general functioning among clinical high-risk individuals in an initial discovery sample (N=422). An independent sample (N=133) was used to test replicability. Results: Three trajectory groups were identified among clinical high-risk individuals in the discovery sample: group 1 (30%) exhibited substantial improvement across all domains, with half reaching positive outcomes for both functioning and positive symptoms; group 2 (49%) exhibited moderate impairments across domains, with approximately one-quarter meeting criteria for positive outcomes; the remaining participants (group 3; 22%) exhibited consistent levels of severe impairment across domains and did not experience positive outcomes. These trajectory groups and remission patterns were replicated in an independent sample. Conclusions: Replicable subgroups of help-seeking clinical high-risk cases can be ascertained based on distinctive profiles of change over time in symptoms and functioning. Within each of the three identified subgroups, similar patterns of change (i.e., rapid, moderate, or no improvement) were observed across the four symptom domains and functioning. This consistency of change over time across domains within each subgroup is a novel observation supporting the syndrome consistency of clinical high-risk symptoms and signs. The observed trajectory subgroups are suggestive of different degrees of need for clinical interventions, ranging from minimal or supportive for about one-third of cases to increasingly intensive among the remainder
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