19 research outputs found

    Continuum Surface Energy from a Lattice Model

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    We investigate connections between the continuum and atomistic descriptions of deformable crystals, using certain interesting results from number theory. The energy of a deformed crystal is calculated in the context of a lattice model with general binary interactions in two dimensions. A new bond counting approach is used, which reduces the problem to the lattice point problem of number theory. The main contribution is an explicit formula for the surface energy density as a function of the deformation gradient and boundary normal. The result is valid for a large class of domains, including faceted (polygonal) shapes and regions with piecewise smooth boundaries.Comment: V. 1: 10 pages, no fig's. V 2: 23 pages, no figures. Misprints corrected. Section 3 added, (new results). Intro expanded, refs added.V 3: 26 pages. Abstract changed. Section 2 split into 2. Section (4) added material. V 4, 28 pages, Intro rewritten. Changes in Sec.5 (presentation only). Refs added.V 5,intro changed V.6 address reviewer's comment

    In Context: Lessons About Adolescent Unipolar Depression From the Improving Mood With Psychoanalytic and Cognitive Therapies Trial

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    This review paper summarizes the results of the Improving Mood with Psychoanalytic and Cognitive Therapies (IMPACT) study and its implications for psychological treatment of adolescents with moderate to severe unipolar major depression. IMPACT was a pragmatic, superiority, randomized controlled trial conducted in the United Kingdom, which compared the clinical and cost-effectiveness of short-term psychoanalytic therapy (STPP), cognitive−behavioral therapy (CBT), and a brief psychosocial intervention (BPI) in reducing depression symptoms in 465 adolescents with unipolar major depression, aged 11 to 17 years. Although this was a clinically heterogeneous group of adolescents, some symptoms (eg, sleep and concentration difficulties, irritability/anger) were common and disabling. The trial reported no significant difference among the 3 treatments in reducing depression symptoms. One year after treatment, 84% of participants showed improvement in depressive symptoms (<50% of baseline symptoms) and improved psychosocial functioning, achieving this through different symptom reduction trajectories. Although participants attended fewer treatment sessions than planned, the 3 treatments were delivered with fidelity to their respective models. Ending treatment without therapist agreement occurred in 37% of cases. This was not associated with outcomes by treatment group. Adolescents emphasized the importance of the therapeutic relationship in all 3 treatments. Results suggest that although most adolescents respond to time-limited, structured psychological therapy, subgroups of depressed adolescents are likely to need additional treatment or support. These include adolescents who live in complex circumstances and/or who believe that their needs are not met in therapy, some who stop treatment early, and the 16% to 18% of adolescents who do not respond to treatment

    Improving the energy performance of UK households: Results from surveys of consumer adoption and use of low- and zero-carbon technologies

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    This paper presents results from a UK Open University project which surveyed consumers' reasons for adoption, and non-adoption, of energy efficiency measures and renewable energy systems–collectively called low- and zero-carbon technologies–and their experiences of using these technologies. Data were gathered during 2006 via an online questionnaire with nearly 400 responses, plus 111 in-depth telephone interviews. The respondents were mainly environmentally concerned, 'green' consumers and therefore these are purposive rather than representative surveys. The paper outlines results for four energy efficiency measures (loft insulation, condensing boilers, heating controls and energy-efficient lighting) and four household renewables (solar thermal water heating, solar photovoltaics, micro-wind turbines and wood-burning stoves). These green consumers typically adopted these technologies to save energy, money and/or the environment, which many considered they achieved despite rebound effects. The reasons for considering but rejecting these technologies include the familiar price barriers, but there were also other obstacles that varied according to the technology concerned. Nearly a third of the surveyed consumers had adopted household renewables, over half of which were wood stoves and 10% solar thermal water heating systems. Most adopters of renewables had previously installed several energy efficiency measures, but only a fifth of those who seriously considered renewables actually installed a system. This suggests sell energy efficiency first, then renewables. There seems to be considerable interest in household renewables in the UK, especially among older, middle-class green consumers, but so far only relatively few pioneers have managed to overcome the barriers to adoption

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

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    INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

    Reduced motor facilitation during action observation in schizophrenia: a mirror neuron deficit?

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    Impairments in social cognitive functioning are well documented in schizophrenia, however the neural basis of these deficits is unclear. A recent explanatory model of social cognition centers upon the activity of mirror neurons, which are cortical brain cells that become active during both the performance and observation of behavior. Here, we test for the first time whether mirror neuron functioning is reduced in schizophrenia. Fifteen individuals with schizophrenia or schizoaffective disorder and fifteen healthy controls completed a transcranial magnetic stimulation (TMS) experiment designed to assess mirror neuron activation. While patients demonstrated no abnormalities in cortical excitability, motor facilitation during action observation, putatively reflecting mirror neuron activity, was reduced in schizophrenia. Dysfunction within the mirror neuron system may contribute to the pathophysiology of schizophrenia

    Mirror neuron activation is associated with facial emotion processing

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    Theoretical accounts suggest that mirror neurons play a crucial role in social cognition. The current study used transcranial-magnetic stimulation (TMS) to investigate the association between mirror neuron activation and facialemotion processing, a fundamental aspect of social cognition, among healthy adults (n = 20). Facial emotion processing of static (but not dynamic) images correlated significantly with an enhanced motor response, proposed to reflect mirror neuron activation. These correlations did not appear to reflect general facial processing or pattern recognition, and provide support to current theoretical accounts linking the mirror neuron system to aspects of social cognition. We discuss the mechanism by which mirror neurons might facilitate facial emotion recognition

    No Consistent Antidepressant Effects of Deep Brain Stimulation of the Bed Nucleus of the Stria Terminalis

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    Background: Applying deep brain stimulation (DBS) to several brain regions has been investigated in attempts to treat highly treatment-resistant depression, with variable results. Our initial pilot data suggested that the bed nucleus of the stria terminalis (BNST) could be a promising therapeutic target. Objective: The aim of this study was to gather blinded data exploring the efficacy of applying DBS to the BNST in patients with highly refractory depression. Method: Eight patients with chronic severe treatment-resistant depression underwent DBS to the BNST. A randomised, double-blind crossover study design with fixed stimulation parameters was followed and followed by a period of open-label stimulation. Results: During the double-blind crossover phase, no consistent antidepressant effects were seen with any of the four stimulation parameters applied, and no patients achieved response or remission criteria during the blinded crossover phase or during a subsequent period of three months of blinded stimulation. Stimulation-related side effects, especially agitation, were reported by a number of patients and were reversible with adjustment of the stimulation parameters. Conclusions: The results of this study do not support the application of DBS to the BNST in patients with highly resistant depression or ongoing research utilising stimulation at this brain site. The blocked randomised study design utilising fixed stimulation parameters was poorly tolerated by the participants and does not appear suitable for assessing the efficacy of DBS at this location
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