191 research outputs found

    Electrochemical energy storage systems for solar thermal applications

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    Existing and advanced electrochemical storage and inversion/conversion systems that may be used with terrestrial solar-thermal power systems are evaluated. The status, cost and performance of existing storage systems are assessed, and the cost, performance, and availability of advanced systems are projected. A prime consideration is the cost of delivered energy from plants utilizing electrochemical storage. Results indicate that the five most attractive electrochemical storage systems are the: iron-chromium redox (NASA LeRC), zinc-bromine (Exxon), sodium-sulfur (Ford), sodium-sulfur (Dow), and zinc-chlorine (EDA)

    The state-of-the-art of dc power distribution systems/components for space applications

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    This report is a survey of the state of the art of high voltage dc systems and components. This information can be used for consideration of an alternative secondary distribution (120 Vdc) system for the Space Station. All HVdc components have been prototyped or developed for terrestrial, aircraft, and spacecraft applications, and are applicable for general space application with appropriate modification and qualification. HVdc systems offer a safe, reliable, low mass, high efficiency and low EMI alternative for Space Station secondary distribution

    True Fiction: Three Writers\u27 Approaches to Fact and/or Fiction

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    This thesis examines how three writers challenge our understandings of the fiction and non-fiction genres

    Penalized Orthogonal Iteration for Sparse Estimation of Generalized Eigenvalue Problem

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    We propose a new algorithm for sparse estimation of eigenvectors in generalized eigenvalue problems (GEP). The GEP arises in a number of modern data-analytic situations and statistical methods, including principal component analysis (PCA), multiclass linear discriminant analysis (LDA), canonical correlation analysis (CCA), sufficient dimension reduction (SDR) and invariant co-ordinate selection. We propose to modify the standard generalized orthogonal iteration with a sparsity-inducing penalty for the eigenvectors. To achieve this goal, we generalize the equation-solving step of orthogonal iteration to a penalized convex optimization problem. The resulting algorithm, called penalized orthogonal iteration, provides accurate estimation of the true eigenspace, when it is sparse. Also proposed is a computationally more efficient alternative, which works well for PCA and LDA problems. Numerical studies reveal that the proposed algorithms are competitive, and that our tuning procedure works well. We demonstrate applications of the proposed algorithm to obtain sparse estimates for PCA, multiclass LDA, CCA and SDR. Supplementary materials are available online

    Breathing Easy: Lung Health and Associated Conditions in the Day Care Setting

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    Introduction: Air pollutants are associated with many health risks. Children in the day care environment are uniquely suscept-ible to lung damage, infection, systemic illness & pollutant triggered hypersensitivity reactions. The latest public report by the CDC reports Vermont’s (VT) asthma rate is the high-est in the country at 11.1%. This project compared VT’s day care regulations regarding specific environmental factors linked with health risks to regulations in six surrounding New England states. We sought to assess whether VT’s regulations adequately protect children in day carehttps://scholarworks.uvm.edu/comphp_gallery/1064/thumbnail.jp

    A Randomized Controlled Trial: Attachment-Based Family and Nondirective Supportive Treatments for Youth Who Are Suicidal

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    Objective: To evaluate the efficacy of attachment-based family therapy (ABFT) compared with a family-enhanced nondirective supportive therapy (FE-NST) for decreasing adolescents’ suicide ideation and depressive symptoms. Method: A randomized controlled trial of 129 adolescents who are suicidal ages 12- to 18-years-old (49% were African American) were randomized to ABFT (n ¼ 66) or FE-NST (n ¼ 63) for 16 weeks of treatment. Assessments occurred at baseline and 4, 8, 12, and 16 weeks. Trajectory of change and clinical recovery were calculated for suicidal ideation and depressive symptoms. Results: There was no significant between-group difference in the rate of change in self-reported ideation (Suicidal Ideation Questionnaire-Jr; F1,127 ¼ 181, p ¼ .18). Similar results were found for depressive symptoms. However, adolescents receiving ABFT showed a significant decrease in suicide ideation (t127 ¼ 12.61, p \u3c .0001; effect size, d ¼ 2.24). Adolescents receiving FE-NST showed a similar significant decrease (t127 ¼ 10.88, p \u3c .0001; effect size, d ¼ 1.93). Response rates (ie, 50% decrease in suicide ideation symptoms from baseline) at post-treatment were 69.1% for ABFT versus 62.3% for FE-NST. Conclusion: Contrary to expectations, ABFT did not perform better than FE-NST. The 2 treatments produced substantial decreases in suicidal ideation and depressive symptoms that were comparable to or better than those reported in other more intensive, multicomponent treatments. The equivalent outcomes could be attributed to common treatment elements, different active mechanisms, or regression to the mean. Future studies will explore long-term follow up, secondary outcomes, and potential moderators and mediators

    Biomechanical and functional variation in rat sciatic nerve following cuff electrode implantation

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    Nerve cuff electrodes are commonly and successfully used for stimulating peripheral nerves. On the other hand, they occasionally induce functional and morphological changes following chronic implantation, for reasons not always clear. We hypothesize that restriction of nerve mobility due to cuff implantation may alter nerve conduction. We quantified acute changes in nerve-muscle electrophysiology, using electromyography, and nerve kinematics in anesthetized Sprague Dawley rat sciatic nerves during controlled hindlimb joint movement. We compared electrophysiological and biomechanical response in uncuffed nerves and those secured within a cuff electrode using analysis of variance (ANOVA) and regression analysis. Tethering resulting from cuff implantation resulted in altered nerve strain and a complex biomechanical environment during joint movement. Coincident with biomechanical changes, electromyography revealed significantly increased variability in the response of conduction latency and amplitude in cuffed, but not free, nerves following joint movement. Our findings emphasize the importance of the mechanical interface between peripheral nerves and their devices on neurophysiological performance. This work has implications for nerve device design, implantation, and prediction of long-term efficacy.https://doi.org/10.1186/1743-0003-11-7

    Combining attachment-based family therapy and cognitive behavioral therapy to improve outcomes for adolescents with anxiety

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    Increases in adolescent anxiety over the past several years suggest a need for trauma-informed, culturally responsive interventions that help teens cope with environmental stressors like those associated with the COVID-19 pandemic. Although abundant evidence supports the efficacy of cognitive behavioral therapy (CBT) in treating adolescent anxiety, not all teens respond positively to CBT. CBT does not typically include strategies that address important family factors that may be impacting the teen’s functioning, such as the attachment relationship. Attachment-based family therapy (ABFT) addresses the attachment relationship and other factors that contribute to the adolescent’s anxiety and related distress. By enhancing positive parenting behaviors, such as acceptance and validation of the adolescent’s distress and promotion of their autonomy, ABFT sessions may repair the attachment relationship and increase the family’s ability and willingness to engage in CBT tasks aimed at reducing anxiety. This theoretical paper describes the ABFT model and proposes that implementing ABFT sessions prior to CBT could result in better clinical outcomes for adolescents with anxiety disorders by improving the context within which the anxiety symptoms and treatment are experienced. Given that ABFT is sensitive and responsive to family and other contextual factors, adolescents from marginalized communities and those from less individualistic cultures may find the model to be more acceptable and appropriate for addressing factors related to their anxiety. Thus, a combined ABFT+CBT model might result in better outcomes for adolescents who have not historically responded well to CBT alone
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