Cardiovascular risk profile of high school students: A cross-sectional study

INTRODUCTION: Disease prevention should begin in childhood and lifestyles are important risk determinants of cardiovascular disease. Awareness and monitoring of risk is essential in preventive strategies. AIM: To characterize cardiovascular risk and the relationships between certain variables in adolescents. METHODS: In a cross-sectional study, 854 adolescent schoolchildren were surveyed, mean age 16.3±0.9 years. Data collection included questionnaires, physical examination, charts for 10-year relative risk of mortality, and biochemical assays. In the statistical analysis continuous variables were studied by the Student's t test and categorical variables by the chi-square test and Fisher's exact test, and each risk factor was entered as a dependent variable in logistic regression analysis. RESULTS: Physical activity was insufficient in 81% of students. The daily consumption of soup, salad or vegetables, and fruit was, respectively, 37%, 39% and 21%. A minority (6%) took ≤3 and 77% took ≥5 meals a day. The prevalence of each risk factor was as follows: overweight 16%; smoking 13%; hypertension 11%; impaired glucose metabolism 9%; hypertriglyceridemia 9%; and hypercholesterolemia 5%. Out-of-school physical activity, hypertension and overweight were more prevalent in males (p<0.001). Females had higher levels of cholesterol (p<0.005) and triglycerides (p<0.001). A quarter of the adolescents had a relative risk score for 10-year cardiovascular mortality of ≥2. Overweight showed a positive association with blood pressure, changes in glucose metabolism and triglycerides, and a negative association with number of daily meals. CONCLUSIONS: The results demonstrate the need for action in providing and encouraging healthy choices for adolescents, with an emphasis on behavioral and lifestyle changes aimed at individuals, families and communitie

Molecular testing of the São Francisco River as an ecological filter for the Brazilian large-eyed stingray Hypanus marianae (Dasyatidae, Myliobatiformes)

Ecological niche modeling (ENM) provides information on the potential environmental barriers to a species that can be tested in phylogeographic studies. A previous ENM analysis of the benthic coastal stingray Hypanus marianae revealed a low suitability area for its occurrence at the São Francisco River (SFR) mouth, the fourth largest river flowing into Southwestern Atlantic. Hence, phylogeographic analyses were used to test the hypothesis of two populations: one north and another south of SFR outflow. We sampled 109 specimens in six localities throughout the species’ geographic distribution and sequenced mitochondrial (cytb) and nuclear (rag1) markers. Our analyses corroborated the existence of two groups (ΦST = 0.68, P < 0.0001) within H. marianae, partially agreeing with the ENM results. The commonest mitochondrial haplotype (H2) was shared among almost all localities, except Salvador, where all individuals shared the same and unique haplotype. This group is restricted to a shallow bay area close to SFR, as predicted by the ENM. However, its plume was not effective in isolating a continental island 55 km off the Brazilian coast. While the broad north group is protected in a few Marine Protected Areas, our results suggest that the restricted southern one deserves to be managed specifically.Fil: Costa, Tiego L. A.. Universidade Federal do Rio Grande; BrasilFil: de Figueiredo Petean, Flávia. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; Argentina. Universidade Federal do Rio Grande; BrasilFil: Berbel Filho, Waldir M.. Universidade Federal do Rio Grande; BrasilFil: Solé Cava, Antonio M.. Universidade Federal do Rio de Janeiro; BrasilFil: Mendes, Liana F.. Universidade Federal do Rio Grande do Norte; BrasilFil: Lima, Sergio M. Q.. Universidade Federal do Rio Grande; Brasi

Dynamic Phase Transition in a Time-Dependent Ginzburg-Landau Model in an Oscillating Field

The Ginzburg-Landau model below its critical temperature in a temporally oscillating external field is studied both theoretically and numerically. As the frequency or the amplitude of the external force is changed, a nonequilibrium phase transition is observed. This transition separates spatially uniform, symmetry-restoring oscillations from symmetry-breaking oscillations. Near the transition a perturbation theory is developed, and a switching phenomenon is found in the symmetry-broken phase. Our results confirm the equivalence of the present transition to that found in Monte Carlo simulations of kinetic Ising systems in oscillating fields, demonstrating that the nonequilibrium phase transition in both cases belongs to the universality class of the equilibrium Ising model in zero field. This conclusion is in agreement with symmetry arguments [G. Grinstein, C. Jayaprakash, and Y. He, Phys. Rev. Lett. 55, 2527 (1985)] and recent numerical results [G. Korniss, C.J. White, P. A. Rikvold, and M. A. Novotny, Phys. Rev. E (submitted)]. Furthermore, a theoretical result for the structure function of the local magnetization with thermal noise, based on the Ornstein-Zernike approximation, agrees well with numerical results in one dimension.Comment: 16 pp. RevTex, 9 embedded ps figure

Absence of First-order Transition and Tri-critical Point in the Dynamic Phase Diagram of a Spatially Extended Bistable System in an Oscillating Field

It has been well established that spatially extended, bistable systems that are driven by an oscillating field exhibit a nonequilibrium dynamic phase transition (DPT). The DPT occurs when the field frequency is on the order of the inverse of an intrinsic lifetime associated with the transitions between the two stable states in a static field of the same magnitude as the amplitude of the oscillating field. The DPT is continuous and belongs to the same universality class as the equilibrium phase transition of the Ising model in zero field [G. Korniss et al., Phys. Rev. E 63, 016120 (2001); H. Fujisaka et al., Phys. Rev. E 63, 036109 (2001)]. However, it has previously been claimed that the DPT becomes discontinuous at temperatures below a tricritical point [M. Acharyya, Phys. Rev. E 59, 218 (1999)]. This claim was based on observations in dynamic Monte Carlo simulations of a multipeaked probability density for the dynamic order parameter and negative values of the fourth-order cumulant ratio. Both phenomena can be characteristic of discontinuous phase transitions. Here we use classical nucleation theory for the decay of metastable phases, together with data from large-scale dynamic Monte Carlo simulations of a two-dimensional kinetic Ising ferromagnet, to show that these observations in this case are merely finite-size effects. For sufficiently small systems and low temperatures, the continuous DPT is replaced, not by a discontinuous phase transition, but by a crossover to stochastic resonance. In the infinite-system limit the stochastic-resonance regime vanishes, and the continuous DPT should persist for all nonzero temperatures

Wave-packet dynamics in slowly perturbed crystals: Gradient corrections and Berry-phase effects

We present a unified theory for wave-packet dynamics of electrons in crystals subject to perturbations varying slowly in space and time. We derive the wave-packet energy up to the first order gradient correction and obtain all kinds of Berry-phase terms for the semiclassical dynamics and the quantization rule. For electromagnetic perturbations, we recover the orbital magnetization energy and the anomalous velocity purely within a single-band picture without invoking inter-band couplings. For deformations in crystals, besides a deformation potential, we obtain a Berry-phase term in the Lagrangian due to lattice tracking, which gives rise to new terms in the expressions for the wave-packet velocity and the semiclassical force. For multiple-valued displacement fields surrounding dislocations, this term manifests as a Berry phase, which we show to be proportional to the Burgers vector around each dislocation.Comment: 12 pages, RevTe

Chaotic hybrid new inflation in supergravity with a running spectral index

We propose an inflation model in supergravity, in which chaotic and hybrid inflation occurs successively, followed by new inflation. During hybrid inflation, adiabatic fluctuations with a running spectral index with \ns >1 on a large scale and \ns <1 on a smaller scale are generated, as favored by recent results of the first year Wilkinson Microwave Anisotropy Probe. The initial condition of new inflation is also set dynamically during hybrid inflation, and its duration and the amplitude of density fluctuations take appropriate values to help early star formation to realize early reionization.Comment: 15 pages, to appear in Phys. Rev.

“Fantasmas” na mecânica quântica

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCan you pick a complex subject in quantum mechanics and discuss it with a minimum number of equations, in a simplified form that the general scientific public could understand? This was a question presented to graduate students of the one-year Quantum Mechanics course based on the text book Modern Quantum Mechanics by J. J. Sakurai and Jim Napolitano, at the State University of Campinas (UNICAMP), Brazil. The first seven authors of this paper are graduate students (alphabetical order) that accepted to try it. The chosen subject was "delocalized quantum states", and it will be discussed using colloquial terms like quantum ghosts, spooky action, splitting beings and invisibility cloak. © Sociedade Brasileira de Física. Printed in Brazil.Can you pick a complex subject in quantum mechanics and discuss it with a minimum number of equations, in a simplified form that the general scientific public could understand? This was a question presented to graduate students of the one-year Quantum Mechanics course based on the text book Modern Quantum Mechanics by J. J. Sakurai and Jim Napolitano, at the State University of Campinas (UNICAMP), Brazil. The first seven authors of this paper are graduate students (alphabetical order) that accepted to try it. The chosen subject was "delocalized quantum states", and it will be discussed using colloquial terms like quantum ghosts, spooky action, splitting beings and invisibility cloak.383111CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOSem informaçãoSem informaçãoSem informaçãoPode-se escolher um topico complexo em mecanica quantica e discuti-lo com um numero mınimo de equações, e de forma simplificada para que um publico com apenas conhecimento basico em fısica possa entender? Essa foi a pergunta apresentada aos alunos de pos-graduação das disciplinas de um ano de Mecanica Quantica I e II da Universidade Estadual de Campinas (UNICAMP), baseadas no livro “Quantum Mechanics” de J. J. Sakurai e Jim Napolitano. Os primeiros sete autores desse artigosão os alunos de pos-graduação (em ordem alfabetica) que aceitaram o desafio. O topico escolhido foi estados quanticos delocalizados, e sera discutido utilizando termos coloquiais como fantasmas quanticos, ações fantasmagoricas, entidades divididas e capa de invisibilidade.G.M.A., D.T.M, M.M. and M.A.P.L acknowledge support from the Brazilian agency “Conselho Nacional de Desenvolvimento Científico e Tecnológico” (CNPq). D.Q.A., L.F.M.C, and S.I.C.G acknowledge support from the Brazilian agency “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior” (CAPES), and L.F.C.F acknowledges support from the Brazilian state of São Paulo agency “Fundação de Amparo à Pesquisa do Estado de São Paulo” (FAPESP). The authors thank Amanda A. R. Lima for drawing the inspiring figure 2. The authors are grateful to Profs. Michael Brunger, Prof. Amir Caldeira and Prof. José A. Roversi for their critical reading of the manuscript and constructive comments and suggestions. The authors also thank for critical reading of this manuscript, the following group of people of the aimed public target: Paulo S. P. Lima (Mechanical Engineer), Martín E. Navarro Maldonado (Chemical Engineer), and Luis Quesada (Professor of Computer Science and Informatics)

Dynamic Phase Transition, Universality, and Finite-size Scaling in the Two-dimensional Kinetic Ising Model in an Oscillating Field

We study the two-dimensional kinetic Ising model below its equilibrium critical temperature, subject to a square-wave oscillating external field. We focus on the multi-droplet regime where the metastable phase decays through nucleation and growth of many droplets of the stable phase. At a critical frequency, the system undergoes a genuine non-equilibrium phase transition, in which the symmetry-broken phase corresponds to an asymmetric stationary limit cycle for the time-dependent magnetization. We investigate the universal aspects of this dynamic phase transition at various temperatures and field amplitudes via large-scale Monte Carlo simulations, employing finite-size scaling techniques adopted from equilibrium critical phenomena. The critical exponents, the fixed-point value of the fourth-order cumulant, and the critical order-parameter distribution all are consistent with the universality class of the two-dimensional equilibrium Ising model. We also study the cross-over from the multi-droplet to the strong-field regime, where the transition disappears