55 research outputs found

    Scaling law in the Standard Map critical function. Interpolating hamiltonian and frequency map analysis

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    We study the behaviour of the Standard map critical function in a neighbourhood of a fixed resonance, that is the scaling law at the fixed resonance. We prove that for the fundamental resonance the scaling law is linear. We show numerical evidence that for the other resonances p/qp/q, q2q \geq 2, p0p \neq 0 and pp and qq relatively prime, the scaling law follows a power--law with exponent 1/q1/q.Comment: AMS-LaTeX2e, 29 pages with 8 figures, submitted to Nonlinearit

    Fundamentos teóricos-práticos e protocolos de extração e de amplificação de DNA por meio da técnica de reação em cadeia de polimerase.

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    Caracterização molecular dos ácidos nucléicos; Obtenção de amostras para extração de dna; Cuidados durante e após a extração de dna; Material necessário para extração de dna; Extração de dna de amostras de tecidos de mamíferos; Material; Digestão da amostra; Extração do dna com fenol; Purificação do dna por meio de precipitação com etanol; Protocolos empregados na rotina de extração de dna de amostras de sangue; Extração de dna de amostras de sangue com a utilização de colunas de extração; Protocolo de extração de dna de sangue mediante precipitação com sal; Extração de dna de amostras congeladas de sangue; Protocolos empregados na extração de dna de amostras de artrópodes com utilização de colunas de purificação; Protocolo para extração de dna de amostras de carrapatos com colunas de purificação 11; Protocolo de extração de dna de ovos de carrapatos com a utilização de colunas de purificação; Extração de dna de amostras de sêmen; Extração de dna de plantas; Leitura da concentração de dna nas amostras Introdução à tecnica de pcr; Escolha dos primers ou iniciadores; Pcr "multiplex" ; Nested-pcr; Pcr quantitativa; Eletroforese de ácidos nucléicos; Eletroforese em gel de agarose; Variáveis que afetam a migração do dna através do gel de agarose; Protocolo para análise de produtos de amplificação e fragmentos de digestão em gel de agarose; Eletroforese em sistema capilar; Protocolo para análise de produtos de amplificação em sistema capilar; Protocolos de amplificação de dna parasitário; Pcr para babesia bigemina; Nested-pcr para babesia bigemina; Eletroforese em gel de agarose para visualização dos produtos amplificados

    Pion production in the inner disk around Cygnus X-1

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    Neutron production via ^{4}He breakup and p(p, n{pi}^+)p is considered in the innermost region of an accretion disk surrounding a Kerr Black Hole. These reactions occur in a plasma in Wien equilibrium, where (radiatively produced) pair production equals annihilation. Cooling of the disk is assumed to be due to unsaturated inverse Comptonization of external soft photons and to the energy needed to ignite both nuclear reactions. Assuming matter composition of 90% Hydrogen and 10% He, it is shown that, close to the border of this region, neutron production is essentially from ^{4}He breakup. Close to the horizon, the contribution from p(p, n{pi}^+)p to the neutron production is comparable to that from the breakup. It is shown that the viscosity generated by the collisions of the accreting matter with the neutrons may drive stationary accretion, for accretion rates below a critical value. In this case, solution to the disk equations is double-valued and for both solutions protons overnumber the pairs. It is claimed that these solutions may mimic the states of high and low luminosity observed in Cygnus X-1 and related sources. This would be explained either by the coupling of thermal instability to the peculiar behavior of the viscosity parameter alpha with the ion temperature that may intermittently switch accretion off or by the impossibility of a perfect tuning for both thermal and pair equilibrium in the disk, a fact that forces the system to undergo a kind of limit cycle behavior around the upper solution.Comment: 23 pages, 11 figure

    Casemix, management, and mortality of patients receiving emergency neurosurgery for traumatic brain injury in the Global Neurotrauma Outcomes Study: a prospective observational cohort study

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    Relationships between outdoor time, physical activity, sedentary time, and body mass index in children : a 12-country study

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    Purpose: This study investigated the relationship between outdoor time and physical activity (PA), sedentary time (SED), and body mass index z scores among children from 12 lower-middle-income, upper-middle-income, and high-income countries. Methods: In total, 6478 children (54.4% girls) aged 9-11 years participated. Outdoor time was self-reported, PA and SED were assessed with ActiGraph GT3X+ accelerometers, and height and weight were measured. Data on parental education, neighborhood collective efficacy, and accessibility to neighborhood recreation facilities were collected from parent questionnaires. Country latitude and climate statistics were collected through national weather data sources. Gender-stratified multilevel models with parental education, climate, and neighborhood variables as covariates were used to examine the relationship between outdoor time, accelerometry measures, and body mass index z scores. Results: Each additional hour per day spent outdoors was associated with higher moderate-to vigorous-intensity PA (boys: +2.8 min/d; girls: +1.4 min/d), higher light-intensity PA (boys: +2.0 min/d; girls: +2.3 min/d), and lower SED (boys: -6.3 min/d; girls: -5.1 min/d). Effect sizes were generally weaker in lower-middle-income countries. Outdoor time was not associated with body mass index z scores. Conclusions: Outdoor time was associated with higher PA and lower SED independent of climate, parental education, and neighborhood variables, but effect sizes were small. However, more research is needed in low-and middle-income countries

    Sleep characteristics and health-related quality of life in 9- to 11-year-old children from 12 countries

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    Introduction: Previous studies have linked short sleep duration, poor sleep quality, and late sleep timing with lower health-related quality of life (HRQoL) in children. However, almost all studies relied solely on self-reported sleep information, and most studies were conducted in high-income countries. To address these gaps, we studied both device-measured and self-reported sleep characteristics in relation to HRQoL in a sample of children from 12 countries that vary widely in terms of economic and human development. Methods: The study sample included 6,626 children aged 9-11 years from Australia, Brazil, Canada, China, Colombia, Finland, India, Kenya, Portugal, South Africa, the United Kingdom, and the United States. Waist-worn actigraphy was used to measure total sleep time, bedtime, wake-up time, and sleep efficiency on both weekdays and weekends. Children also reported ratings of sleep quantity and quality. HRQoL was measured by the KIDSCREEN-10 survey. Multilevel regression models were used to determine the relationships between sleep characteristics and HRQoL. Results: Results showed considerable variation in sleep characteristics, particularly duration and timing, across study sites. Overall, we found no association between device-measured total sleep time, sleep timing or sleep efficiency, and HRQoL. In contrast, self-reported ratings of poor sleep quantity and quality were associated with HRQoL. Conclusions: Self-reported, rather than device-based, measures of sleep are related to HRQoL in children. The discrepancy related to sleep assessment methods highlights the importance of considering both device-measured and self-reported measures of sleep in understanding its health effects
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