406 research outputs found

    Instability of scale-free networks under node-breaking avalanches

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    The instability introduced in a large scale-free network by the triggering of node-breaking avalanches is analyzed using the fiber-bundle model as conceptual framework. We found, by measuring the size of the giant component, the avalanche size distribution and other quantities, the existence of an abrupt transition. This test of strength for complex networks like Internet is more stringent than others recently considered like the random removal of nodes, analyzed within the framework of percolation theory. Finally, we discuss the possible implications of our results and their relevance in forecasting cascading failures in scale-free networks.Comment: 4 pages, 4 figures, final version to be published in Europhys. Let

    Kaon production in heavy-ion collisions and maximum mass of neutron stars

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    We determine an `empirical' kaon dispersion relation by analysing and fitting recent experimental data on kaon production in heavy-ion collisions. We then investigate its effects on hadronic equation of state at high densities and on neutron star properties. We find that the maximum mass of neutron stars can be lowered by about 0.4MM_\odot, once kaon condensation as constrained by our empirical dispersion relation is introduced. We emphasize the growing interplay between hadron physics, relativistic heavy-ion physics and the physics of compact objects in astrophysics.Comment: 6 pages with 3 postscript figures, to appear in Physical Review Letter

    Co-Evolution of quasispecies: B-cell mutation rates maximize viral error catastrophes

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    Co-evolution of two coupled quasispecies is studied, motivated by the competition between viral evolution and adapting immune response. In this co-adaptive model, besides the classical error catastrophe for high virus mutation rates, a second ``adaptation-'' catastrophe occurs, when virus mutation rates are too small to escape immune attack. Maximizing both regimes of viral error catastrophes is a possible strategy for an optimal immune response, reducing the range of allowed viral mutation rates to a minimum. From this requirement one obtains constraints on B-cell mutation rates and receptor lengths, yielding an estimate of somatic hypermutation rates in the germinal center in accordance with observation.Comment: 4 pages RevTeX including 2 figure

    Voltage Regulator Module Noise Analysis for High-Volume Server Applications

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    This paper presents a methodology to analyze voltage regulator module (VRM) noise coupling problems in high-volume server applications. The technique is applied on a real engineering design. The comprehensive model includes irregular power shapes, decoupling capacitors, and dielectric and conductive loss. Irregular shaped power plane modeling is cross-checked with four separate methods to demonstrate accuracy

    Community perspectives of complex trauma assessment for Aboriginal parents: 'Its important, but how these discussions are held is critical'

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    Background and Purpose: Becoming a parent can be an exciting and also challenging transition, particularly for parents who have experienced significant hurt in their own childhoods, and may be experiencing ‘complex trauma.’ Aboriginal and Torres Strait Islander (Aboriginal) people also experience historical trauma. While the parenting transition is an important time to offer support for parents, it is essential to ensure that the benefits of identifying parents experiencing complex trauma outweigh any risks (e.g., stigmatization). This paper describes views of predominantly Aboriginal stakeholders regarding (1) the relative importance of domains proposed for complex trauma assessment, and (2) how to conduct these sensitive discussions with Aboriginal parents. Setting and Methods: A co-design workshop was held in Alice Springs (Central Australia) as part of an Aboriginal-led community-based participatory action research project. Workshop participants were 57 predominantly Aboriginal stakeholders with expertise in community, clinical, policy and academic settings. Twelve domains of complex trauma-related distress had been identified in existing assessment tools and through community consultation. Using story-telling and strategies to create safety for discussing complex and sensitive issues, and delphi-style methods, stakeholders rated the level of importance of the 12 domains; and discussed why, by whom, where and how experiences of complex trauma should be explored. Main Findings: The majority of stakeholders supported the importance of assessing each of the proposed complex trauma domains with Aboriginal parents. However, strong concerns were expressed regarding where, by whom and how this should occur. There was greater emphasis and consistency regarding ‘qualities’ (e.g., caring), rather than specific ‘attributes’ (e.g., clinician). Six critical overarching themes emerged: ensuring emotional and cultural safety; establishing relationships and trust; having capacity to respond appropriately and access support; incorporating less direct cultural communication methods (e.g., yarning, dadirri); using strengths-based approaches and offering choices to empower parents; and showing respect, caring and compassion. Conclusion: Assessments to identify Aboriginal parents experiencing complex trauma should only be considered when the prerequisites of safety, trusting relationships, respect, compassion, adequate care, and capacity to respond are assured. Offering choices and cultural and strengths-based approaches are also critical. Without this assurance, there are serious concerns that harms may outweigh any benefits for Aboriginal parents

    Barriers to Family Caregivers’ Coping With Patients With Severe Mental Illness in Iran

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    The broad spectrum of problems caused by caring for a patient with mental illness imposes a high burden on family caregivers. This can affect how they cope with their mentally ill family members. Identifying caregivers’ experiences of barriers to coping is necessary to develop a program to help them overcome these challenges. This qualitative content analysis study explored barriers impeding family caregivers’ ability to cope with their relatives diagnosed with severe mental illness (defined here as schizophrenia, schizoaffective disorders, and bipolar affective disorders). Sixteen family caregivers were recruited using purposive sampling and interviewed using a semi-structured in-depth interview method. Data were analyzed by a conventional content analytic approach. Findings consisted of four major categories: the patient’s isolation from everyday life, incomplete recovery, lack of support by the mental health care system, and stigmatization. Findings highlight the necessity of providing support for caregivers by the mental health care delivery service system.The study was supported by Grant TBZMED·REC.5825 from the deputy of research in Tabriz University of Medical Sciences

    The association between intimate partner violence, alcohol and depression in family practice

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    Background: Depressive symptoms, intimate partner violence and hazardous drinking are common among patients attending general practice. Despite the high prevalence of these three problems; the relationship between them remains relatively unexplored. Methods: This paper explores the association between depressive symptoms, ever being afraid of a partner and hazardous drinking using cross-sectional screening data from 7667 randomly selected patients from a large primary care cohort study of 30 metropolitan and rural general practices in Victoria, Australia. The screening postal survey included the Center for Epidemiological Studies Depression Scale, the Fast Alcohol Screening Test and a screening question from the Composite Abuse Scale on ever being afraid of any intimate partner. Results: 23.9% met criteria for depressive symptoms. A higher proportion of females than males (20.8% vs. 7.6%) reported ever being afraid of a partner during their lifetime (OR 3.2, 95%CI 2.5 to 4.0) and a lower proportion of females (12%) than males (25%) were hazardous drinkers (OR 0.4; 95%CI 0.4 to 0.5); and a higher proportion of females than males (20.8% vs. 7.6%) reported ever being afraid of a partner during their lifetime (OR 3.2, 95%CI 2.5 to 4.0). Men and women who had ever been afraid of a partner or who were hazardous drinkers had on average higher depressive symptom scores than those who had never been afraid or who were not hazardous drinkers. There was a stronger association between depressive symptoms and ever been afraid of a partner compared to hazardous drinking for both males (ever afraid of partner; Diff 6.87; 95% CI 5.42, 8.33; p < 0.001 vs. hazardous drinking in last year; Diff 1.07, 95% CI 0.21, 1.94; p = 0.015) and females (ever afraid of partner; Diff 5.26; 95% CI 4.55, 5.97; p < 0.001 vs. hazardous drinking in last year; Diff 2.23, 95% CI 1.35, 3.11; p < 0.001), even after adjusting for age group, income, employment status, marital status, living alone and education level. Conclusions: Strategies to assist primary care doctors to recognise and manage intimate partner violence and hazardous drinking in patients with depression may lead to better outcomes from management of depression in primary care
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