120 research outputs found

    Modeling, Evaluation, and Scale on Artificial Pedestrians: A Literature Review

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    Modeling pedestrian dynamics and their implementation in a computer are challenging and important issues in the knowledge areas of transportation and computer simulation. The aim of this article is to provide a bibliographic outlook so that the reader may have quick access to the most relevant works related to this problem. We have used three main axes to organize the article's contents: pedestrian models, validation techniques, and multiscale approaches. The backbone of this work is the classification of existing pedestrian models; we have organized the works in the literature under five categories, according to the techniques used for implementing the operational level in each pedestrian model. Then the main existing validation methods, oriented to evaluate the behavioral quality of the simulation systems, are reviewed. Furthermore, we review the key issues that arise when facing multiscale pedestrian modeling, where we first focus on the behavioral scale (combinations of micro and macro pedestrian models) and second on the scale size (from individuals to crowds). The article begins by introducing the main characteristics of walking dynamics and its analysis tools and concludes with a discussion about the contributions that different knowledge fields can make in the near future to this exciting area

    Strong one-neutron emission from two-neutron unbound states in β decays of the r -process nuclei Ga 86,87

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    β-delayed one-neutron and two-neutron branching ratios (P1n and P2n) have been measured in the decay of A=84 to 87 Ga isotopes at the Radioactive-Isotope Beam Factory (RIBF) at the RIKEN Nishina Center using a high-efficiency array of He3 neutron counters (BRIKEN). Two-neutron emission was observed in the decay of Ga84,85,87 for the first time and the branching ratios were measured to be P2n=1.6(2)%,1.3(2)%, and 10.2(28)stat(5)sys%, respectively. One-neutron branching ratio of Ga87(P1n=81(9)stat(8)sys%) and half-life of 29(4) ms were measured for the first time. The branching ratios of Ga86 were also measured to be P1n=74(2)stat(8)sys% and 16.2(9)stat(6)sys% with better precision than a previous study. The observation that P1n>P2n for both Ga86,87 was unexpected and is interpreted as a signature of dominating one-neutron emission from the two-neutron unbound excited states in Ge86,87. In order to interpret the experimental results, shell-model and Hauser-Feshbach statistical model calculations of delayed particle and γ-ray emission probabilities were performed. This model framework reproduces the experimental results. The shell model alone predicts P2n significantly larger than P1n for the Ga87 decay, and it is necessary to invoke a statistical description to successfully explain the observation that P1n>P2n. Our new results demonstrate the relevance and importance of a statistical description of neutron emission for the prediction of the decay properties of multineutron emitters and that it must be included in the r-process modeling

    Commissioning of the BRIKEN detector for the measurement of very exotic β-delayed neutron emitters

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    A new detection system has been installed at the RIKEN Nishina Center (Japan) to investigate decay properties of very neutron-rich nuclei. The setup consists of three main parts: a moderated neutron counter, a detection system sensitive to the implantation and decay of radioactive ions, and gamma-ray detectors. We describe here the setup, the commissioning experiment and some selected results demonstrating its performance for the measurement of half-lives and beta-delayed neutron emission probabilities. The methodology followed in the analysis of the data is described in detail. Particular emphasis is placed on the correction of the accidental neutron background

    ß-delayed neutron emission of r-process nuclei at the N=82 shell closure

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    Theoretical models of ß-delayed neutron emission are used as crucial inputs in r-process calculations. Benchmarking the predictions of these models is a challenge due to a lack of currently available experimental data. In this work the ß-delayed neutron emission probabilities of 33 nuclides in the important mass regions south and south-west of 132Sn are presented, 16 for the first time. The measurements were performed at RIKEN using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The values presented constrain the predictions of theoretical models in the region, affecting the final abundance distribution of the second r-process peak at .Peer ReviewedArticle signat per 58 autors/es J. Liu, S. Bae, N.T. Brewer, C.G. Bruno, R. Caballero-Folch, P.J. Coleman-Smith, I. Dillmann, C. Domingo-Pardo, A. Fijalkowska, N. Fukuda, S. Go, C.J. Griffin, R. Grzywacz, J. Ha, L. J. Harkness-Brennan, T. Isobe, D. Kahl, L.H. Khiem, G.G. Kiss, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, P. Morrall, M.R. Mumpower, N. Nepal, R.D. Page, M. Piersa , V.F.E. Pucknell , B.C. Rasco, B. Rubio, K.P. Rykaczewski , H. Sakurai , Y. Shimizu , D.W. Stracener, T. Sumikama , H. Suzuki, J.L. Tain , H. Takeda, A. Tarifeño-Saldivia, A. Tolosa-Delgado , M. Wolinska-Cichocka , R. YokoyamaPostprint (author's final draft

    A comprehensive overview of grain development in Brachypodium distachyon variety Bd21

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    A detailed and comprehensive understanding of seed reserve accumulation is of great importance for agriculture and crop improvement strategies. This work is part of a research programme aimed at using Brachypodium distachyon as a model plant for cereal grain development and filling. The focus was on the Bd21-3 accession, gathering morphological, cytological, and biochemical data, including protein, lipid, sugars, starch, and cell-wall analyses during grain development. This study highlighted the existence of three main developmental phases in Brachypodium caryopsis and provided an extensive description of Brachypodium grain development. In the first phase, namely morphogenesis, the embryo developed rapidly reaching its final morphology about 18 d after fertilization (DAF). Over the same period the endosperm enlarged, finally to occupy 80% of the grain volume. During the maturation phase, carbohydrates were continuously stored, mainly in the endosperm, switching from sucrose to starch accumulation. Large quantities of β-glucans accumulated in the endosperm with local variations in the deposition pattern. Interestingly, new β-glucans were found in Brachypodium compared with other cereals. Proteins (i.e. globulins and prolamins) were found in large quantities from 15 DAF onwards. These proteins were stored in two different sub-cellular structures which are also found in rice, but are unusual for the Pooideae. During the late stage of development, the grain desiccated while the dry matter remained fairly constant. Brachypodium exhibits some significant differences with domesticated cereals. Beta-glucan accumulates during grain development and this cell wall polysaccharide is the main storage carbohydrate at the expense of starch

    Commissioning of the BRIKEN detector for the measurement of very exotic β-delayed neutron emitters

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    A new detection system has been installed at the RIKEN Nishina Center (Japan) to investigate decay properties of very neutron-rich nuclei. The setup consists of three main parts: a moderated neutron counter, a detection system sensitive to the implantation and decay of radioactive ions, and γ-ray detectors. We describe here the setup, the commissioning experiment and some selected results demonstrating its performance for the measurement of half-lives and β-delayed neutron emission probabilities. The methodology followed in the analysis of the data is described in detail. Particular emphasis is placed on the correction of the accidental neutron background

    Is concern about young people's anti-social behaviour associated with poor health? cross-sectional evidence from residents of deprived urban neighbourhoods

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    <p><b>Background:</b> Young people in disadvantaged neighbourhoods are often the focus of concerns about anti-social behaviour (ASB). There is inconsistent evidence to support the hypothesis that perceptions of ASB (PASB) are associated with poor health. We ask whether perceptions of young people's ASB are associated with poor health; and whether health, demographic and (psycho)social characteristics can help explain why PASB varies within disadvantaged neighbourhoods (Glasgow, UK).</p> <p><b>Methods:</b> Regression analysis of survey data exploring associations between perceiving teenagers hanging around to be a serious neighbourhood problem and SF-12v2 mental and physical health scores (higher = better), including adjustment for demographic characteristics. Further analysis explored associations with self-reported measures of health service use, psychosocial characteristics of homes and neighbourhoods and social contacts.</p> <p><b>Results:</b> 6008 adults participated (50% response) and 22% (n = 1,332) said teenagers were a serious neighbourhood problem (the most frequently reported local problem). Demographic characteristics associated with perceiving serious teenager problems included regular health service use, age (inverse relationship), financial problems and living with children. Lower SF-12v2 physical health scores were associated with perceiving teenager problems after adjustment for demographic variables (OR 0.98; 95%CI 0.97,0.99; p = < 0.001), whilst adjusted findings for mental health scores were less conclusive (OR 0.99; 95%CI 0.98,1.00; p = 0.103). Further analysis suggested that perceiving teenager problems was more strongly associated with a number of self-reported psychosocial factors: e.g. lacking social support, < weekly family contacts, poor neighbourhood safety, low trust in neighbours, neighbourhood perceived to be a barrier to self-esteem, and neighbourhood decline.</p> <p><b>Conclusions:</b> Given the evidence we found of weak and small associations between PASB and health, we caution against assuming that tackling concern about teenagers' ASB will lead to substantial public health gains in disadvantaged areas. Although the findings do not present a compelling case for making PASB a public health priority, it is still important to address concerns about young people's ASB. Reasons for doing so may include improving social cohesion, reducing fear and isolation, and improving the general quality of people's lives - particularly in neighbourhoods burdened by multiple disadvantages. Future research should evaluate interventions that attempt to reduce PASB in disadvantaged areas. Findings from this study could help inform the targeting of such interventions.</p&gt

    Reclaiming the humanity in personality Disorder.

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    This paper provides a commentary upon the nursing care of individuals diagnosed with personality disorder and associated education courses. The discussion focuses upon recent policy trends in the UK as a point of departure. This policy discourse is critical of mainstream mental health services in previously operating to exclude such individuals. One of the consequences has been a recent growth in interest in relevant training courses, many of which devote significant attention to staff attitudes regarding this client group. Various previous researchers and commentators have remarked upon the implications for practice of a perceived negative attitude among care staff. We reflect upon our own anecdotal experience of developing and delivering new university-based courses for practitioners working in the field of personality disorder to offer a particular critique of the UK context, in which this policy, training, and practice is framed. Social constructionist theories are drawn on to offer insights into public and practitioner discourse and the possible effects on therapeutic relationships. The available discourse constructs individuals with a diagnosis of personality disorder as essentially different from other people. We argue that staff training and practice development initiatives are likely to be more successful if such discourse is challenged, and attempts are made in therapeutic encounters to recognize shared characteristics and positive attributes as much as perceived difference and negative attributes. We refer to this as a re-engagement with common humanity. Despite the singular national context, the discursive themes explored are not necessarily restricted to the UK

    <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> -delayed neutron emissions from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>&gt;</mml:mo><mml:mn>50</mml:mn></mml:mrow></mml:math> gallium isotopes

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    β-delayed γ-neutron spectroscopy has been performed on the decay of A=84 to 87 gallium isotopes at the RI-beam Factory at the RIKEN Nishina Center using a high-efficiency array of He3 neutron counters (BRIKEN). β-2n-γ events were measured in the decays of all of the four isotopes for the first time, which is direct evidence for populating the excited states of two-neutron daughter nuclei. Detailed decay schemes with the γ branching ratios were obtained for these isotopes, and the neutron emission probabilities (Pxn) were updated from the previous study. Hauser-Feshbach statistical model calculations were performed to understand the experimental branching ratios. We found that the P1n and P2n values are sensitive to the nuclear level densities of 1n daughter nuclei and showed that the statistical model reproduced the P2n/P1n ratio better when experimental levels plus shell-model level densities fit by the Gilbert-Cameron formula were used as the level-density input. We also showed the neutron and γ branching ratios are sensitive to the ground-state spin of the parent nucleus. Our statistical model analysis suggested J≤3 for the unknown ground-state spin of the odd-odd nucleus Ga86, from the Iγ(4+→2+)/Iγ(2+→0+) ratio of Ga84 and the P2n/P1n ratio. These results show the necessity of detailed understanding of the decay scheme, including data from neutron spectroscopy, in addition to γ measurements of the multineutron emitters
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