The effect of phase transitions on the droplet size distribution in homogeneous isotropic turbulence

We investigate the dynamics of an ensemble of discrete aerosol droplets in a homogeneous, isotropic turbulent flow. Our focus is on the stationary distribution of droplet sizes that develops as a result of evaporation and condensation effects. For this purpose we simulate turbulence in a domain with periodic boundary conditions using pseudo-spectral discretization. We solve in addition equations for the temperature and for a scalar field, which represents the background humidity against which the size of the droplets evolves. We apply large-scale forcing of the velocity field to reach a statistically steady state. The droplets are transported by the turbulent field while exchanging heat and mass with the evolving temperature and humidity fields. In this Euler-Lagrange framework, we assume the droplets volume fraction to be sufficiently low to allow one-way coupling of the droplets and turbulence dynamics. The motion of the droplets is time-accurately tracked. The Stokes drag force is included in the equation of motion of the individual droplets. The responsiveness of the droplets to small turbulent scales is directly related to the size of the individual spherical droplets. We perform direct numerical simulation to ultimately obtain the probability density function of the evolving radius of the droplets at different points in time with characteristic heat and mass transfer parameters. We determine the gradual convergence of the distribution function to its statistically stationary state for forced homogeneous, isotropic turbulence

Caracterização bioquímica e molecular de doentes com diagnóstico clínico de Dislipidemia Familiar Combinada

A Dislipidemia Familiar Combinada (FCHL) é uma doença poligénica caracterizada por hiperlipidemia simples ou combinada, variabilidade intra-individual e intra-familiar do perfil lipídico, ApoB elevada (> 120 mg/dL) e risco elevado de doença cardiovascular (DCV). A sua causa é desconhecida mas alterações nos genes LPL, APOAIV, APOAV, APOCIII e USF1 parecem contribuir para o seu fenótipo. O objectivo deste estudo é caracterizar bioquímica e molecularmente doentes com diagnóstico clínico de FCHL. Todos os exões e promotor dos genes LPL, APOAIV, APOAV, APOCIII e regiões do gene USF1 (s1,s2) de 41 doentes foram amplificados por PCR e sequenciados. O colesterol total (CT), c-LDL, c-HDL, sdLDL, trigliceridos (TG), apoB e apoCIII foram determinados num aparelho automatizado. Em alguns doentes as sdLDL foram também analisadas por electroforese de lipoproteínas. A ApoAIV e ApoAV foram quantificadas por ELISA. Foram encontradas alterações genéticas em 37 doentes, 3 não descritas (APOAIV Q359_E362, APOAV D332fsX336 e APOCIII 3269C>A). O índex com a alteração Q359_E362del apresentou valores normais de apo AIV (15.5 mg/dL) e o índex com a alteração D332fsX336 apresentou valores baixos de apo AV (74.5 ng/mL). Os doentes estudados apresentam valores elevados de CT (285 ± 83 mg/dL), c-LDL (189 ± 85 mg/dL), TG (310 ± 253 mg/dL), e apo CIII (15 ± 4 mg/dL) e valores reduzidos de c-HDL (45 ± 11 mg/dL), sem medicação. Os valores de apoAIV (17,5 ± 10,4 mg/dL) e apoAV (150 ± 135 ng/mL) encontram-se, na maioria dos casos, no intervalo normal assim como os valores de sdLDL (35 ± 18 mg/dL), no entanto alguns casos apresentam valores acima do cut-off para DCV (35 mg/dL). A análise de sdLDL por electroforese foi realizada em 11 doentes, 9 dos quais apresentaram um perfil aterogénico. O valor médio de ApoB destes doentes era de 94 ± 43 mg/dL, mas aproximadamente 70% dos doentes estavam medicados com terapêutica hipolimiante (estatinas e/ou fibratos). Cerca de 30% dos doentes apresentavam DCV prematura. Os resultados obtidos parecem indicar que alterações nos genes estudados influenciam o fenótipo da FCHL. Os níveis séricos de apo CIII encontram-se alterados nesta dislipidemia. Doentes com FCHL, apesar de estarem medicados, apresentam valores elevados de sdLDL, evidenciando o seu elevado risco cardiovascular. A caracterização bioquímica complementa a identificação genética e permite uma melhor avaliação do risco cardiovascular do doente bem como a escolha de uma terapêutica adequada

C-axis lattice dynamics in Bi-based cuprate superconductors

We present results of a systematic study of the c axis lattice dynamics in single layer Bi2Sr2CuO6 (Bi2201), bilayer Bi2Sr2CaCu2O8 (Bi2212) and trilayer Bi2Sr2Ca2Cu3O10 (Bi2223) cuprate superconductors. Our study is based on both experimental data obtained by spectral ellipsometry on single crystals and theoretical calculations. The calculations are carried out within the framework of a classical shell model, which includes long-range Coulomb interactions and short-range interactions of the Buckingham form in a system of polarizable ions. Using the same set of the shell model parameters for Bi2201, Bi2212 and Bi2223, we calculate the frequencies of the Brillouin-zone center phonon modes of A2u symmetry and suggest the phonon mode eigenvector patterns. We achieve good agreement between the calculated A2u eigenfrequencies and the experimental values of the c axis TO phonon frequencies which allows us to make a reliable phonon mode assignment for all three Bi-based cuprate superconductors. We also present the results of our shell model calculations for the Gamma-point A1g symmetry modes in Bi2201, Bi2212 and Bi2223 and suggest an assignment that is based on the published experimental Raman spectra. The superconductivity-induced phonon anomalies recently observed in the c axis infrared and resonant Raman scattering spectra in trilayer Bi2223 are consistently explained with the suggested assignment.Comment: 29 pages, 13 figure

Human toxocariasis: contribution by Brazilian researchers

In the present paper the main aspects of the natural history of human infection by Toxocara larvae that occasionally result in the occurrence of visceral and/or ocular larva migrans syndrome were reviewed. The contribution by Brazilian researchers was emphasized, especially the staff of the Tropical Medicine Institute of São Paulo (IMT)