372 research outputs found

    Evo-devo of human adolescence: beyond disease models of early puberty

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    Despite substantial heritability in pubertal development, much variation remains to be explained, leaving room for the influence of environmental factors to adjust its phenotypic trajectory in the service of fitness goals. Utilizing evolutionary development biology (evo-devo), we examine adolescence as an evolutionary life-history stage in its developmental context. We show that the transition from the preceding stage of juvenility entails adaptive plasticity in response to energy resources, other environmental cues, social needs of adolescence and maturation toward youth and adulthood. Using the evolutionary theory of socialization, we show that familial psychosocial stress fosters a fast life history and reproductive strategy rather than early maturation being just a risk factor for aggression and delinquency. Here we explore implications of an evolutionary-developmental-endocrinological-anthropological framework for theory building, while illuminating new directions for research

    First Neutrino Observations from the Sudbury Neutrino Observatory

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    The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed.Comment: Latex, 7 pages, 10 figures, Invited paper at Neutrino 2000 Conference, Sudbury, Canada, June 16-21, 2000 to be published in the Proceeding

    Search for astronomical neutrinos from blazar TXS 0506+056 in super-kamiokande

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    We report a search for astronomical neutrinos in the energy region from several GeV to TeV in the direction of the blazar TXS 0506+056 using the Super-Kamiokande detector following the detection of a 100 TeV neutrinos from the same location by the IceCube collaboration. Using Super-Kamiokande neutrino data across several data samples observed from 1996 April to 2018 February we have searched for both a total excess above known backgrounds across the entire period as well as localized excesses on smaller timescales in that interval. No significant excess nor significant variation in the observed event rate are found in the blazar direction. Upper limits are placed on the electron- and muon-neutrino fluxes at the 90% confidence level as 6.0 × 10−7 and 4.5 × 10−7–9.3 × 10−10 [erg cm−2 s−1], respectively

    Systematic Development of the YouRAction program, a computer-tailored Physical Activity promotion intervention for Dutch adolescents, targeting personal motivations and environmental opportunities

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    Background. Increasing physical activity (PA) among adolescents is an important health promotion goal. PA has numerous positive health effects, but the majority of Dutch adolescents do not meet PA requirements. The present paper describes the systematic development of a theory-based computer-tailored intervention, YouRAction, which targets individual and environmental factors determining PA among adolescents. Design. The intervention development was guided by the Intervention Mapping protocol, in order to define clear program objectives, theoretical methods and practical strategies, ensure systematic program planning and pilot-testing, and anticipate on implementation and evaluation. Two versions of YouRAction were developed: one that targets individual determinants and an extended version that also provides feedback on opportunities to be active in the neighbourhood. Key determinants that were targeted included: knowledge and awareness, attitudes, self-efficacy and subjective norms. The extended version also addressed perceived availability of neighbourhood PA facilities. Both versions aimed to increase levels of moderate-to-vigorous PA among adolescents. The intervention structure was based on self-regulation theory, comprising of five steps in the process of successful goal pursuit. Monitoring of PA behaviour and behavioural and normative feedback were used to increase awareness of PA behaviour; motivation was enhanced by targeting self-efficacy and attitudes, by means of various interactive strategies, such as web movies; the perceived environment was targeted by visualizing opportunities to be active in an interactive geographical map of the home environment; in the goal setting phase, the adolescents were guided in setting a goal and developing an action plan to achieve this goal; in the phase of active goal pursuit adolescents try to achieve their goal and in the evaluation phase the achievements are evaluated. Based on the results of the evaluation adolescents could revise their goal or choose another behaviour to focus on. The intervention is delivered in a classroom setting in three lessons. YouRAction will be evaluated in a cluster-randomized trial, with classes as unit of randomization. Evaluation will focus on PA outcomes, cognitive mediators/moderators and process measures. Discussion. The planned development of YouRAction resulted in two computer-tailored interventions aimed at the promotion of PA in a Dutch secondary school setting. Trial registration. NTR1923

    University rankings:What do they really show?

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    University rankings as developed by the media are used by many stakeholders in higher education: students looking for university places; academics looking for university jobs; university managers who need to maintain standing in the competitive arena of student recruitment; and governments who want to know that public funds spent on universities are delivering a world class higher education system. Media rankings deliberately draw attention to the performance of each university relative to all others, and as such they are undeniably simple to use and interpret. But one danger is that they are potentially open to manipulation and gaming because many of the measures underlying the rankings are under the control of the institutions themselves. This paper examines media rankings (constructed from an amalgamation of variables representing performance across numerous dimensions) to reveal the problems with using a composite index to reflect overall performance. It ends with a proposal for an alternative methodology which leads to groupings rather than point estimates

    Relacao entre o nivel de atividade fisica estimado pelo Baltimore Activity Scale for Intermittent Claudication e a pedometria em pacientes com claudicacao intermitente

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    CONTEXTO: Os pacientes com claudicação intermitente apresentam nĂ­veis reduzidos de atividade fĂ­sica. A Baltimore Activity Scale for Intermittent Claudication (BASIC) foi validada para quantificar o nĂ­vel de atividade fĂ­sica destes pacientes. No entanto, esta validação se baseou em apenas dois dias de monitoramento com acelerĂŽmetros, de modo que ainda permanece incerto se a BASIC fornece informaçÔes sobre os nĂ­veis de atividade fĂ­sica semanal. OBJETIVO: Analisar a correlação entre o nĂ­vel de atividade fĂ­sica estimada pela BASIC e o nĂ­vel obtido pelo pedĂŽmetro em uma semana, em pacientes com claudicação intermitente. MÉTODOS: Foram estudados 150 pacientes com claudicação intermitente, com idade entre 30 e 80 anos. Foram obtidos os dados sociodemogrĂĄficos e verificada a presença de comorbidades e de fatores de risco cardiovascular, e a BASIC. O pedĂŽmetro foi utilizado por sete dias consecutivos, sendo a anĂĄlise feita em trĂȘs diferentes perĂ­odos de monitorização (todos os dias, dias da semana e do fim de semana). RESULTADOS: Foi observada correlação entre a BASIC e a mĂ©dia de passos de todos os dias (rho=0,343; p<0,001), dos dias de semana (rho=0,336; p<0,001) e dos dias do final de semana (rho=0,317; p<0,001). CONCLUSÃO: Em pacientes com claudicação intermitente, o nĂ­vel de atividade fĂ­sica estimado pela BASIC se correlaciona com o nĂ­vel de atividade fĂ­sica semanal

    Erythropoietin Improves the Survival of Fat Tissue after Its Transplantation in Nude Mice

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    Background: Autologous transplanted fat has a high resorption rate, providing a clinical challenge for the means to reduce it. Erythropoietin (EPO) has non-hematopoietic targets, and we hypothesized that EPO may improve long-term fat graft survival because it has both pro-angiogenic and anti-apoptotic properties. We aimed to determine the effect of EPO on the survival of human fat tissue after its transplantation in nude mice. Methodology/Principal Findings: Human fat tissue was injected subcutaneously into immunologically-compromised nude mice, and the grafts were then treated with either 20 IU or 100 IU EPO. At the end of the 15-week study period, the extent of angiogenesis, apoptosis, and histology were assessed in the fat grafts. The results were compared to vascular endothelial growth factor (VEGF)-treated and phosphate-buffered saline (PBS)-treated fat grafts. The weight and volume of the EPOtreated grafts were higher than those of the PBS-treated grafts, whose weights and volumes were not different from those of the VEGF-treated grafts. EPO treatment also increased the expression of angiogenic factors and microvascular density, and reduced inflammation and apoptosis in a dose-dependent manner in the fat grafts. Conclusions/Significance: Our data suggest that stimulation of angiogenesis by a cluster of angiogenic factors and decreased fat cell apoptosis account for potential mechanisms that underlie the improved long-term survival of fa

    Accurate Encoding and Decoding by Single Cells: Amplitude Versus Frequency Modulation

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    Cells sense external concentrations and, via biochemical signaling, respond by regulating the expression of target proteins. Both in signaling networks and gene regulation there are two main mechanisms by which the concentration can be encoded internally: amplitude modulation (AM), where the absolute concentration of an internal signaling molecule encodes the stimulus, and frequency modulation (FM), where the period between successive bursts represents the stimulus. Although both mechanisms have been observed in biological systems, the question of when it is beneficial for cells to use either AM or FM is largely unanswered. Here, we first consider a simple model for a single receptor (or ion channel), which can either signal continuously whenever a ligand is bound, or produce a burst in signaling molecule upon receptor binding. We find that bursty signaling is more accurate than continuous signaling only for sufficiently fast dynamics. This suggests that modulation based on bursts may be more common in signaling networks than in gene regulation. We then extend our model to multiple receptors, where continuous and bursty signaling are equivalent to AM and FM respectively, finding that AM is always more accurate. This implies that the reason some cells use FM is related to factors other than accuracy, such as the ability to coordinate expression of multiple genes or to implement threshold crossing mechanisms
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