221 research outputs found

    Functional approach to the electromagnetic response function: the Longitudinal Channel

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    In this paper we address the (charge) longitudinal electromagnetic response for a homogeneous system of nucleons interacting via meson exchanges in the functional framework. This approach warrants consistency if the calculation is carried on order-by-order in the mesonic loop expansion with RPA-dressed mesonic propagators. At the 1-loop order and considering pion, rho and omega exchanges we obtain a quenching of the response, in line with the experimental results.Comment: RevTeX, 18 figures available upon request - to be published in Physical Review

    Longitudinal and Transverse Quasi-Elastic Response Functions of Light Nuclei

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    The 3^3He and 4^4He longitudinal and transverse response functions are determined from an analysis of the world data on quasi-elastic inclusive electron scattering. The corresponding Euclidean response functions are derived and compared to those calculated with Green's function Monte Carlo methods, using realistic interactions and currents. Large contributions associated with two-body currents are found, particularly in the 4^4He transverse response, in agreement with data. The contributions of two-body charge and current operators in the 3^3He, 4^4He, and 6^6Li response functions are also studied via sum-rule techniques. A semi-quantitative explanation for the observed systematics in the excess of transverse quasi-elastic strength, as function of mass number and momentum transfer, is provided. Finally, a number of model studies with simplified interactions, currents, and wave functions is carried out to elucidate the role played, in the full calculation, by tensor interactions and correlations.Comment: 40 pages, 11 figures, submitted to Phys. Rev.

    Superscaling of Inclusive Electron Scattering from Nuclei

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    We investigate the degree to which the concept of superscaling, initially developed within the framework of the relativistic Fermi gas model, applies to inclusive electron scattering from nuclei. We find that data obtained from the low energy loss side of the quasielastic peak exhibit the superscaling property, i.e., the scaling functions f(\psi') are not only independent of momentum transfer (the usual type of scaling: scaling of the first kind), but coincide for A \geq 4 when plotted versus a dimensionless scaling variable \psi' (scaling of the second kind). We use this behavior to study as yet poorly understood properties of the inclusive response at large electron energy loss.Comment: 33 pages, 12 color EPS figures, LaTeX2e using BoxedEPSF macros; email to [email protected]

    Quasielastic 12C(e,e'p) Reaction at High Momentum Transfer

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    We measured the 12C(e,e'p) cross section as a function of missing energy in parallel kinematics for (q,w) = (970 MeV/c, 330 MeV) and (990 MeV/c, 475 MeV). At w=475 MeV, at the maximum of the quasielastic peak, there is a large continuum (E_m > 50 MeV) cross section extending out to the deepest missing energy measured, amounting to almost 50% of the measured cross section. The ratio of data to DWIA calculation is 0.4 for both the p- and s-shells. At w=330 MeV, well below the maximum of the quasielastic peak, the continuum cross section is much smaller and the ratio of data to DWIA calculation is 0.85 for the p-shell and 1.0 for the s-shell. We infer that one or more mechanisms that increase with ω\omega transform some of the single-nucleon-knockout into multinucleon knockout, decreasing the valence knockout cross section and increasing the continuum cross section.Comment: 14 pages, 7 figures, Revtex (multicol, prc and aps styles), to appear in Phys Rev

    D-cycloserine augmentation of exposure-based cognitive behavior therapy for anxiety, obsessive-compulsive, and posttraumatic stress disorders: a systematic review and meta-analysis of individual participant data

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    Importance: Whether and under which conditions D-cycloserine (DCS) augments the effects of exposure-based cognitive behavior therapy for anxiety, obsessive-compulsive, and posttraumatic stress disorders is unclear. Objective: To clarify whether DCS is superior to placebo in augmenting the effects of cognitive behavior therapy for anxiety, obsessive-compulsive, and posttraumatic stress disorders and to evaluate whether antidepressants interact with DCS and the effect of potential moderating variables. Data Sources: PubMed, EMBASE, and PsycINFO were searched from inception to February 10, 2016. Reference lists of previous reviews and meta-analyses and reports of randomized clinical trials were also checked. Study Selection: Studies were eligible for inclusion if they were (1) double-blind randomized clinical trials of DCS as an augmentation strategy for exposure-based cognitive behavior therapy and (2) conducted in humans diagnosed as having specific phobia, social anxiety disorder, panic disorder with or without agoraphobia, obsessive-compulsive disorder, or posttraumatic stress disorder. Data Extraction and Synthesis: Raw data were obtained from the authors and quality controlled. Data were ranked to ensure a consistent metric across studies (score range, 0-100). We used a 3-level multilevel model nesting repeated measures of outcomes within participants, who were nested within studies. Results: Individual participant data were obtained for 21 of 22 eligible trials, representing 1047 of 1073 eligible participants. When controlling for antidepressant use, participants receiving DCS showed greater improvement from pretreatment to posttreatment (mean difference, -3.62; 95% CI, -0.81 to -6.43; P = .01; d = -0.25) but not from pretreatment to midtreatment (mean difference, -1.66; 95% CI, -4.92 to 1.60; P = .32; d = -0.14) or from pretreatment to follow-up (mean difference, -2.98, 95% CI, -5.99 to 0.03; P = .05; d = -0.19). Additional analyses showed that participants assigned to DCS were associated with lower symptom severity than those assigned to placebo at posttreatment and at follow-up. Antidepressants did not moderate the effects of DCS. None of the prespecified patient-level or study-level moderators was associated with outcomes. Conclusions and Relevance: D-cycloserine is associated with a small augmentation effect on exposure-based therapy. This effect is not moderated by the concurrent use of antidepressants. Further research is needed to identify patient and/or therapy characteristics associated with DCS response.2018-05-0

    Deploying the NASA Valkyrie Humanoid for IED Response: An Initial Approach and Evaluation Summary

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    As part of a feasibility study, this paper shows the NASA Valkyrie humanoid robot performing an end-to-end improvised explosive device (IED) response task. To demonstrate and evaluate robot capabilities, sub-tasks highlight different locomotion, manipulation, and perception requirements: traversing uneven terrain, passing through a narrow passageway, opening a car door, retrieving a suspected IED, and securing the IED in a total containment vessel (TCV). For each sub-task, a description of the technical approach and the hidden challenges that were overcome during development are presented. The discussion of results, which explicitly includes existing limitations, is aimed at motivating continued research and development to enable practical deployment of humanoid robots for IED response. For instance, the data shows that operator pauses contribute to 50\% of the total completion time, which implies that further work is needed on user interfaces for increasing task completion efficiency.Comment: 2019 IEEE-RAS International Conference on Humanoid Robot

    Oral Pirfenidone in patients with chronic fibrosis resulting from radiotherapy: a pilot study

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    <p>Abstract</p> <p>Background</p> <p>Fibrosis is a common side effect after treatment with ionizing radiation. Several methods to ameliorate debilitating fibrosis have been employed but without consistent results. The goal of this pilot study is to determine if Pirfenidone, a novel regulator of cytokine gene expression, has the potential to ameliorate established radiation-induced fibrosis.</p> <p>Methods</p> <p>Open label, prospective pilot study of 800 mg three times/day, orally administered Pirfenidone was administered to enrolled patients who were had completed radiation therapy and who had established radiation-induced fibrosis. Range of motion (ROM) was assessed using standard measures, and subjective measures of pain, fatigue, disability and global health were measured every three months.</p> <p>Results</p> <p>Seven patients were enrolled of whom 3 had ROM assessments of 1 site and 2 had ROM assessments of 2 sites. Of these assessments, 6 revealed increased ROM during drug intervention while 1 revealed a decreased ROM. There was an overall improvement in the mental composite score of the SF36 while physical composite score was decreased and the vitality score was unchanged. Two patients were removed from the study because of syncopal episodes.</p> <p>Conclusion</p> <p>Several patients experienced improved function of at least 25% and reported subjective improvement. Pirfenidone may benefit patients with radiation-induced fibrosis and is worthy of a larger well controlled trial.</p
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