77 research outputs found

    Nuclear matter at high density: Phase transitions, multiquark states, and supernova outbursts

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    Phase transition from hadronic matter to quark-gluon matter is discussed for various regimes of temperature and baryon number density. For small and medium densities, the phase transition is accurately described in the framework of the Field Correlation Method, whereas at high density predictions are less certain and leave room for the phenomenological models. We study formation of multiquark states (MQS) at zero temperature and high density. Relevant MQS components of the nuclear matter can be described using a previously developed formalism of the quark compound bags (QCB). Partial-wave analysis of nucleon-nucleon scattering indicates the existence of 6QS which manifest themselves as poles of PP-matrix. In the framework of the QCB model, we formulate a self-consistent system of coupled equations for the nucleon and 6QS propagators in nuclear matter and the G-matrix. The approach provides a link between high-density nuclear matter with the MQS components and the cumulative effect observed in reactions on the nuclei, which requires the admixture of MQS in the wave functions of nuclei kinematically. 6QS determine the natural scale of the density for a possible phase transition into the MQS phase of nuclear matter. Such a phase transition can lead to dynamic instability of newly born protoneutron stars and dramatically affect the dynamics of supernovae. Numerical simulations show that the phase transition may be a good remedy for the triggering supernova explosions in the spherically symmetric supernova models. A specific signature of the phase transition is an additional neutrino peak in the neutrino light curve. For a Galactic core-collapse supernova, such a peak could be resolved by the present neutrino detectors. The possibility of extracting the parameters of the phase of transition from observation of the neutrino signal is discussed also.Comment: 57 pages, 22 figures, 7 tables; RevTeX 4; submitted to Phys. Atom. Nuc

    Cenário E Perspectiva Da Produção Científica Sobre Competência Em Informação (coinfo) No Brasil: Estudo Da Produção No âmbito Da Ancib

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    Search highlight in the field of Information Science in Brazil, the importance of the publications generated by scientific events, specifically the scope of information literacy (Competência em Informação - CoInfo, in Portuguese), analyzing the work and the production of its main scientific society, the Associação Nacional de Pesquisa e Pós-Graduação em Ciência da Informação - ANCIB. Presents the results of research that involved the document corpus published in the editions of the Encontro Nacional de Pesquisa e Pós-Graduação em Ciência da Informação - Enancib, annual scientific agenda ANCIB, watching literature produced by scientific work on CoInfo presented in all Anais of the Enancib in the period 1994-2015, identifying theme insertion in all of its major working groups. The research used exploratory and descriptive approach, involving documentary and historical research. The search was carried out in the event portal ANCIB-Enancib, from the selection of the works related to the theme CoInfo and seven related terms: information literacy, competência informacional, alfabetização informacional, aprendizagem informacional, alfabetização em informação, letramento informacional, user education. For measurement data we used the Bardin technique. The results show that as of 2009 there is an increase in the production of work on CoInfo presented in Enancib, indicating that the spaces commonly used for the application of methodologies are libraries. These results also show that the document corpus dealing with the subject and the growing interest of researchers for it, coupled with the possibilities of seminars involving this theme in focus in recent programming Post-Enancib's, provides a very promising future vision for the studies, research and the effective consolidation of CoInfo in the field of Information Science in Brazil, and its visibility. In conclusion, presents the efforts made by various institutions for the development of CoInfo in Brazil in international impact event.26315116

    The Anterior Cingulate Cortex Predicts Future States to Mediate Model-Based Action Selection

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    Behavioral control is not unitary. It comprises parallel systems, model based and model free, that respectively generate flexible and habitual behaviors. Model-based decisions use predictions of the specific consequences of actions, but how these are implemented in the brain is poorly understood. We used calcium imaging and optogenetics in a sequential decision task for mice to show that the anterior cingulate cortex (ACC) predicts the state that actions will lead to, not simply whether they are good or bad, and monitors whether outcomes match these predictions. ACC represents the complete state space of the task, with reward signals that depend strongly on the state where reward is obtained but minimally on the preceding choice. Accordingly, ACC is necessary only for updating model-based strategies, not for basic reward-driven action reinforcement. These results reveal that ACC is a critical node in model-based control, with a specific role in predicting future states given chosen actions.Akam et al. investigate mouse anterior cingulate cortex (ACC) in a sequential decision-making task, finding that ACC predicts future states given chosen actions and indicates when these predictions are violated. Transiently inhibiting ACC prevents mice from using observed state transitions to guide subsequent choices, impairing model-based reinforcement learning

    Motivos da prática de dança de salão nas aulas de educação física escolar

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    O estudo de corte transversal analisou os motivos da prática da dança de salão nas aulas de Educação Física escolar de escolas particulares, relacionando-os com o gênero, seu tempo de prática e participação em eventos de dança de salão. Obteve-se uma amostra de 279 alunos com idade de 15,5 ± 1,0 anos, matriculados nas aulas de dança de salão como Educação Física escolar. Aplicou-se o questionário de motivação para as atividades desportivas - QMAD, adaptado de SERPA e FRIAS (1990) e SERPA (1991). Analisou-se os dados através da estatística descritiva e inferencial, com nível de significância de 95%. Foram encontradas associações significativas entre os motivos e gêneros (r = 0,285; - 0,172); tempo de prática (r = 0,174) e frequência em eventos (r = 0,122; - 0,156). A dança de salão oferece em sua prática uma ferramenta de inúmeras possibilidades, onde cada um de seus praticantes procura preencher as suas próprias necessidades. De acordo com os resultados levantados percebe-se que os alunos estão motivados com a prática de dança de salão na escola havendo diferenças entre o gênero, o tempo de prática e a frequência nos eventos. Diante disto sugere-se a criação de propostas metodológicas condizentes com os principais motivos dos alunos nas aulas de dança de salão dentro do ambiente da Educação Física escolar.The transversal study analyzed the reasons for the practice of ballroom dance in the curricular physical activity in private schools, relating them to the gender, its practice time and participation in ballroom dance events. The study was composed of 279 students at the age of 15.5 ± 1.0, enrolled in ballroom dance as part of regular physical education. The Sport Motivation Questionnaire - SMQ, adapted from SERPA and FRIAS (1990), SERPA (1992) was used. The descriptive and inferential statistics were used with a 95% significance level. Significant associations were found between reasons and the genders (r = 0.285; - 0.172); practice time (r = 0.174) and event frequency (r = 0.122; - 0.156). The ballroom dance offers in its practice a tool of countless possibilities, in which each of its participants search to fulfil their own necessities. According to the risen results it is noticeable that students are motivated with the practice of ballroom dance in schools presenting differences in gender, practice time, and event attendance. Then, it is suggested the creation of methodological proposals coherent to the main goals of the students of ballroom dance within the regular physical education environment in schools

    Atividade da colinesterase plasmática como biomarcador de impacto ambiental em tartarugas verdes (Chelonia mydas) no litoral do Arquipélago de Fernando de Noronha, Pernambuco

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    Biomarcadores podem ser usados de forma preditiva, permitindo que sejam tomadas ações de controle antes que ocorram danos ambientais irreversíveis com consequências ecológicas severas, no entanto, espécies sentinelas são necessárias para avaliação desses marcadores. As tartarugas marinhas são consideradas espécies sentinelas quando acometidas por fibropapilomas, sendo sinalizadora do desequilíbrio ambiental marinho nas suas áreas de ocorrência. Com o objetivo de propor a determinação da atividade da colinesterase plasmática em tartarugas verdes (Chelonia mydas) como biomarcador, procedeu-se a determinação da atividade enzimática em animais saudáveis e em localidade de baixo impacto antrópico (Arquipélago de Fernando de Noronha, Pernambuco, Brasil) para servir como referência para comparação com animais capturados em locais de maior impacto antrópico. Ao todo foram analisadas amostras de plasma heparinizado de 35 animais capturados. Todas as amostras analisadas apresentaram alguma atividade enzimática de colinesterase plasmática. Os valores obtidos de colinesterase variaram de 162 a 379 UI/L, com média e desvio padrão de 216,4 ± 51,4 UI/L. Nos estudos de repetibilidade e reprodutibilidade obtiveram-se coeficientes de variação menor que 5% em todas as análises, portanto a metodologia analítica utilizada se mostrou confiável. A longevidade das tartarugas marinhas da espécie C. mydas, o comportamento alimentar, juntamente com o fato de possuirem atividade enzimática detectável podem indicar essa espécie como bioindicadora de exposição a poluentes que influenciam na atividade da colinesterase plasmátic

    Thematic characterization of research on Information Science in Brazil from 2000-2009

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    Este artículo tiene por objetivo analizar cuáles han sido los principales temas de interés en el campo de la investigación científica dentro del área de la Ciencia de la Información en Brasil a lo largo de la primera década de este siglo (2000-2009). Para ello se ha analizado el contenido de la producción científica publicada en cuatro de las principales revistas nacionales de la disciplina: Ciência da Informação, DataGramaZero, Perspectivas em Ciência da Informação y Transinformação. La metodología aplicada se basa en el análisis de co-ocurrencia de palabras-clave y en la representación e interpretación de los resultados por medio del análisis de redes sociales. Para dotar de un marco de interpretación a los resultados obtenidos se propone una comparación con las áreas temáticas propuestas por la Associação Nacional de Pesquisa e Pós-Graduação em Ciência da Informação en sus Grupos de Trabajo por tratarse de un espacio institucionalizado en donde, por consenso, se debate la investigación en la Ciencia de la Información brasileña. Se concluye en que es el estudio de la propia disciplina la que acapara los mayores esfuerzos de investigación

    The comparative responsiveness of Hospital Universitario Princesa Index and other composite indices for assessing rheumatoid arthritis activity

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    Objective To evaluate the responsiveness in terms of correlation of the Hospital Universitario La Princesa Index (HUPI) comparatively to the traditional composite indices used to assess disease activity in rheumatoid arthritis (RA), and to compare the performance of HUPI-based response criteria with that of the EULAR response criteria. Methods Secondary data analysis from the following studies: ACT-RAY (clinical trial), PROAR (early RA cohort) and EMECAR (pre-biologic era long term RA cohort). Responsiveness was evaluated by: 1) comparing change from baseline (Delta) of HUPI with Delta in other scores by calculating correlation coefficients; 2) calculating standardised effect sizes. The accuracy of response by HUPI and by EULAR criteria was analyzed using linear regressions in which the dependent variable was change in global assessment by physician (Delta GDA-Phy). Results Delta HUPI correlation with change in all other indices ranged from 0.387 to 0.791); HUPI's standardized effect size was larger than those from the other indices in each database used. In ACT-RAY, depending on visit, between 65 and 80% of patients were equally classified by HUPI and EULAR response criteria. However, HUPI criteria were slightly more stringent, with higher percentage of patients classified as non-responder, especially at early visits. HUPI response criteria showed a slightly higher accuracy than EULAR response criteria when using Delta GDA-Phy as gold standard. Conclusion HUPI shows good responsiveness in terms of correlation in each studied scenario (clinical trial, early RA cohort, and established RA cohort). Response criteria by HUPI seem more stringent than EULAR''s
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