1,305 research outputs found

    Physics of Neutron Star Kicks

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    It is no longer necessary to `sell' the idea of pulsar kicks, the notion that neutron stars receive a large velocity (a few hundred to a thousand km s−1^{-1}) at birth. However, the origin of the kicks remains mysterious. We review the physics of different kick mechanisms, including hydrodynamically driven, neutrino and magnetically driven kicks.Comment: 8 pages including 1 figure. To be published in "Stellar Astrophysics" (Pacific Rim Conference Proceedings), (Kluwer Pub.

    Neutrino-driven Explosions

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    The question why and how core-collapse supernovae (SNe) explode is one of the central and most long-standing riddles of stellar astrophysics. A solution is crucial for deciphering the SN phenomenon, for predicting observable signals such as light curves and spectra, nucleosynthesis, neutrinos, and gravitational waves, for defining the role of SNe in the evolution of galaxies, and for explaining the birth conditions and properties of neutron stars (NSs) and stellar-mass black holes. Since the formation of such compact remnants releases over hundred times more energy in neutrinos than the SN in the explosion, neutrinos can be the decisive agents for powering the SN outburst. According to the standard paradigm of the neutrino-driven mechanism, the energy transfer by the intense neutrino flux to the medium behind the stagnating core-bounce shock, assisted by violent hydrodynamic mass motions (sometimes subsumed by the term "turbulence"), revives the outward shock motion and thus initiates the SN blast. Because of the weak coupling of neutrinos in the region of this energy deposition, detailed, multidimensional hydrodynamic models including neutrino transport and a wide variety of physics are needed to assess the viability of the mechanism. Owing to advanced numerical codes and increasing supercomputer power, considerable progress has been achieved in our understanding of the physical processes that have to act in concert for the success of neutrino-driven explosions. First studies begin to reveal observational implications and avenues to test the theoretical picture by data from individual SNe and SN remnants but also from population-integrated observables. While models will be further refined, a real breakthrough is expected through the next Galactic core-collapse SN, when neutrinos and gravitational waves can be used to probe the conditions deep inside the dying star. (abridged)Comment: Author version of chapter for 'Handbook of Supernovae,' edited by A. Alsabti and P. Murdin, Springer. 54 pages, 13 figure

    The meaning of confidence for older people living with frailty

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    © 2017 THE JOANNA BRIGGS INSTITUTE. EXECUTIVE SUMMARYBackground In many countries, the oldest old (those aged 85 years and older) are now the fastest growing proportion of the total population. This oldest population will increasingly be living with the clinical condition of frailty. Frailty syndromes negatively impact on the person as they do the healthcare systems supporting them. Within healthcare literature "loss of confidence" is occasionally connected to older people living with frailty, but ambiguously described. Understanding the concept of confidence within the context of frailty could inform interventions to meet this growing challenge. Objectives The objective of this systematic review was to explore the meaning of confidence from the perspective of older people living with frailty through synthesis of qualitative evidence to inform healthcare practice, research and policy. Inclusion criteria Types of participants Studies that included frail adults, aged over 60 years, experiencing acute hospital and or post-acute care in the last 12 months. Phenomena of interest The concept of "confidence" and its impact on the physical health and mental well-being of older people living with frailty. Context Studies that reported on the older person's descriptions, understanding and meaning of confidence in relation to their frailty or recent healthcare experiences. Types of studies Studies of qualitative design and method. Search strategy A three step search strategy was used. The search strategy explored published studies and gray literature. Publications in English from the last 20 years were considered for inclusion. Methodological quality All included articles were assessed by two independent reviewers using the Joanna Briggs Institute Qualitative Assessment Review Instrument (JBI-QARI). Data extraction Data were extracted from included studies using the data extraction tools developed by the Joanna Briggs Institute. Data synthesis Qualitative research findings were collated using a meta-aggregative approach and JBI-QARI software. Results Synthesized findings of this review were drawn from just four research studies that met the inclusion criteria. Only six findings contributed to the creation of three categories. These informed a single synthesized finding: Vulnerability, described as a fragile state of well-being that is exposed to the conflicting tensions between physical, emotional and social factors. These tensions have the capability to enhance or Erode this state. Conclusions Assertions that an understanding of the concept confidence has been reached cannot be made. The review data offer limited insight into the concept of confidence being described by the cohort of older people living with frailty

    Ecological and methodological drivers of species' distribution and phenology responses to climate change

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    Climate change is shifting species’ distribution and phenology. Ecological traits, such as mobility or reproductive mode, explain variation in observed rates of shift for some taxa. However, estimates of relationships between traits and climate responses could be influenced by how responses are measured. We compiled a global data set of 651 published marine species’ responses to climate change, from 47 papers on distribution shifts and 32 papers on phenology change. We assessed the relative importance of two classes of predictors of the rate of change, ecological traits of the responding taxa and methodological approaches for quantifying biological responses. Methodological differences explained 22% of the variation in range shifts, more than the 7.8% of the variation explained by ecological traits. For phenology change, methodological approaches accounted for 4% of the variation in measurements, whereas 8% of the variation was explained by ecological traits. Our ability to predict responses from traits was hindered by poor representation of species from the tropics, where temperature isotherms are moving most rapidly. Thus, the mean rate of distribution change may be underestimated by this and other global syntheses. Our analyses indicate that methodological approaches should be explicitly considered when designing, analysing and comparing results among studies. To improve climate impact studies, we recommend that (1) reanalyses of existing time series state how the existing data sets may limit the inferences about possible climate responses; (2) qualitative comparisons of species’ responses across different studies be limited to studies with similar methodological approaches; (3) meta-analyses of climate responses include methodological attributes as covariates; and (4) that new time series be designed to include the detection of early warnings of change or ecologically relevant change. Greater consideration of methodological attributes will improve the accuracy of analyses that seek to quantify the role of climate change in species’ distribution and phenology changes

    Strengthening confidence in climate change impact science

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    Aim: To assess confidence in conclusions about climate-driven biological change through time, and identify approaches for strengthening confidence scientific conclusions about ecological impacts of climate change. Location: Global. Methods: We outlined a framework for strengthening confidence in inferences drawn from biological climate impact studies through the systematic integration of prior expectations, long-term data and quantitative statistical procedures. We then developed a numerical confidence index (Cindex) and used it to evaluate current practices in 208 studies of marine climate impacts comprising 1735 biological time series. Results: Confidence scores for inferred climate impacts varied widely from 1 to 16 (very low to high confidence). Approximately 35% of analyses were not associated with clearly stated prior expectations and 65% of analyses did not test putative non-climate drivers of biological change. Among the highest-scoring studies, 91% tested prior expectations, 86% formulated expectations for alternative drivers but only 63% statistically tested them. Higher confidence scores observed in studies that did not detect a change or tracked multiple species suggest publication bias favouring impact studies that are consistent with climate change. The number of time series showing climate impacts was a poor predictor of average confidence scores for a given group, reinforcing that vote-counting methodology is not appropriate for determining overall confidence in inferences. Main conclusions: Climate impacts research is expected to attribute biological change to climate change with measurable confidence. Studies with long-term, high-resolution data, appropriate statistics and tests of alternative drivers earn higher Cindex scores, suggesting these should be given greater weight in impact assessments. Together with our proposed framework, the results of our Cindex analysis indicate how the science of detecting and attributing biological impacts to climate change can be strengthened through the use of evidence-based prior expectations and thorough statistical analyses, even when data are limited, maximizing the impact of the diverse and growing climate change ecology literature

    The web-based ASSO-food frequency questionnaire for adolescents: relative and absolute reproducibility assessment

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    Background: A new food frequency questionnaire (FFQ) has been recently developed within the Italian Adolescents and Surveillance System for the Obesity prevention (ASSO) Project; it was found to be appropriate for ranking adolescents in food and nutrient levels of intake. The aim of this study was to assess the relative and absolute reproducibility of the ASSO-FFQ for 24 food groups, energy and 52 nutrients. Methods: A test-retest study was performed on two ASSO-FFQs administered one month apart of each other to 185 adolescents, aged 14–17 and attending secondary schools in Palermo (Italy). Wilcoxon test assessed differences in median daily intakes between the two FFQs. Agreement was evaluated by quintiles comparison and weighted kappa. Intraclass Correlation Coefficients (ICC) and Bland-Altman method assessed the relative and absolute reliability respectively. Results: Significant difference (p < 0.05) in median intakes was found only for bread substitutes, savoury food, water, soft drinks, carbohydrates and sugar. The subjects classified into the same or adjacent quintiles for food groups ranged from 62% (white bread) to 91% (soft drinks); for energy and nutrients from 64% (polyunsaturated fatty acids) to 90% (ethanol). Mean values of weighted kappa were 0.47 and 0.48, respectively for food groups and nutrients. Fair to good ICC values (>0.40) were assessed for thirteen food groups, energy and forty-three nutrients. Limits of Agreement were narrow for almost all food groups and all nutrients. Conclusions: The ASSO-FFQ is a reliable instrument for estimating food groups, energy and nutrients intake in adolescents

    HABIT-an early phase study to explore an oral health intervention delivered by health visitors to parents with young children aged 9-12 months: study protocol.

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    Background: Parental supervised brushing (PSB) when initiated in infancy can lead to long-term protective home-based oral health habits thereby reducing the risk of dental caries. However, PSB is a complex behaviour with many barriers reported by parents hindering its effective implementation. Within the UK, oral health advice is delivered universally to parents by health visitors and their wider teams when children are aged between 9 and 12 months. Nevertheless, there is no standardised intervention or training upon which health visitors can base this advice, and they often lack the specialised knowledge needed to help parents overcome barriers to performing PSB and limiting sugary foods and drinks.Working with health visitors and parents of children aged 9-24 months, we have co-designed oral health training and resources (Health Visitors delivering Advice in Britain on Infant Toothbrushing (HABIT) intervention) to be used by health visitors and their wider teams when providing parents of children aged 9-12 months with oral health advice.The aim of the study is to explore the acceptability of the HABIT intervention to parents and health visitors, to examine the mechanism of action and develop suitable objective measures of PSB. Methods/design: Six health visitors working in a deprived city in the UK will be provided with training on how to use the HABIT intervention. Health visitors will then each deliver the intervention to five parents of children aged 9-12 months. The research team will collect measures of PSB and dietary behaviours before and at 2 weeks and 3 months after the HABIT intervention. Acceptability of the HABIT intervention to health visitors will be explored through semi-structured diaries completed after each visit and a focus group discussion after delivery to all parents. Acceptability of the HABIT intervention and mechanism of action will be explored briefly during each home visit with parents and in greater details in 20-25 qualitative interviews after the completion of data collection. The utility of three objective measures of PSB will be compared with each other and with parental-self reports. Discussion: This study will provide essential information to inform the design of a definitive cluster randomised controlled trial. Trial registration: There is no database for early phase studies such as ours

    Gastrointestinal stromal tumour and hypoglycemia in a Fjord pony: Case report

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    <p>Abstract</p> <p>Background</p> <p>Neoplasia may cause hypoglycemia in different species including the horse, but hypoglycemia has not previously been reported in the horse associated with gastrointestinal stromal tumours.</p> <p>Case presentation</p> <p>A case of a gastrointestinal stromal tumour in a Fjord pony with severe recurrent hypoglycemia is presented. The mechanism causing the hypoglycemia was not established.</p> <p>Conclusion</p> <p>This case indicates that a gastrointestinal stromal tumour may cause hypoglycemia also in the horse.</p

    Absence of disparities in anthropometric measures among Chilean indigenous and non-indigenous newborns

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    <p>Abstract</p> <p>Background</p> <p>Studies throughout North America and Europe have documented adverse perinatal outcomes for racial/ethnic minorities. Nonetheless, the contrast in newborn characteristics between indigenous and non-indigenous populations in Latin America has been poorly characterized. This is due to many challenges, including a lack of vital registration information on ethnicity. The objective of this study was to analyze trends in anthropometric measures at birth in Chilean indigenous (Mapuche) and non-indigenous children over a 5-year period.</p> <p>Methods</p> <p>We examined weight and length at birth using information available through a national data base of all birth records for the years 2000 through 2004 (n = 1,166.513). Newborns were classified ethnically according to the origins of the parents' last names.</p> <p>Result</p> <p>The average birthweight was stable over the 5 year period with variations of less than 20 g in each group, and with mean values trivially higher in indigenous newborns. The proportion weighing less than 2500 g at birth increased modestly from 5.2% to 5.6% in non-indigenous newborns whereas the indigenous births remained constant at 5.2%. In multiple regression analyses, adjusting flexibly for gestational age and maternal characteristics, the occurrence of an indigenous surname added only 14 g to an average infant's birthweight while holding other factors constant. Results for length at birth were similar, and adjusted time trend variation in both outcomes was trivially small after adjustment. Anthropometric indexes at birth in Chile are quite favorable by international standards.</p> <p>Conclusion</p> <p>There is only a trivial degree of ethnic disparity in these values, in contrast to conditions for ethnic minorities in other countries. Moreover, these values remained roughly constant over the 5 years of observation in this study.</p
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