214 research outputs found
On the excitation of PG1159-type pulsations
No full textStability properties are presented of dipole and quadrupole nonradial oscillation modes of model stars that experienced a late helium shell flash on their way to the white-dwarf cooling domain. The computed instability domains are compared with the observed hot variable central stars of planetary nebulae and the GW Vir pulsators.Fil: Gautschy, Alfred. International Astronomical Union; SuizaFil: Althaus, Leandro Gabriel. Universidad Politecnica de Catalunya; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Saio, Hirouki. Tohoku University; Japó
A influência do gênero e ordem de nascimento sobre as práticas educaticas parentais
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-Graduação em Psicologia.A presente pesquisa teve como objetivo levantar dados sobre a influência do gênero e da ordem de nascimento dos filhos sobre as práticas educativas parentais, investigando também a percepção da preferência parental e a autodescrição de adolescentes. O modelo teórico utilizado para avaliar as práticas educativas inclui sete categorias: duas relativas a práticas denominadas positivas (monitoria positiva e comportamento moral); e cinco negativas (punição inconsistente, negligência, disciplina relaxada, monitoria negativa e abuso físico). Participaram da pesquisa 322 adolescentes entre 13 e 17 anos, sendo 59% do sexo feminino. Os resultados indicaram que as filhas avaliaram a figura paterna de forma mais negativa do que os filhos, não havendo diferenças na avaliação materna geral. As filhas primogênitas alegaram sofrer mais as práticas de punição inconsistente e abuso físico por parte das mães e dos pais; enquanto os filhos mais velhos julgaram apanhar mais da figura paterna. As filhas primogênitas obtiveram maiores valores para monitoria negativa paterna. Primogênitos de ambos os sexos diferenciaram-se dos demais grupos por acreditarem que existe preferência parental por um dos filhos, atribuindo-a principalmente aos caçulas. Houve associação entre os índices de estilo parental e a percepção da preferência parental. Com relação à autodescrição, os participantes dividiram-se principalmente segundo conceitos atribuídos ao gênero. Evidencia-se que o gênero e a ordem de nascimento modulam o modo como os pais tratam os filhos e como os próprios filhos avaliam os pais; esse último aspecto sofrendo influência dos irmãos dentro da relação fraternal. This work aimed at searching data about gender and birth order influence on parenting, also investigating perceived parental favoritism and self-description of adolescents. The theoretical model used to assess the parenting practices includes seven categories: two related to positive practices (positive monitoring and moral modeling), and five related to negative practices (inconsistent punishment, negligence, careless discipline, negative monitoring and physical abuse). The participants were 322 adolescents between ages 13 and 17, 59% girls. Results indicated that girl assessed fathers more negatively than boys, which did not happen for mothers in the general score. Firstborn girls believe to suffer more inconsistent punishment and physical abuse from mothers and fathers, while firstborn boys agree to be more spanked by fathers. Firstborn girls also obtained higher scores for paternal negative monitoring. Firstborns of both sexes differed from other groups for the perceived parental favoritism, especially attributed to laterborns. An association between perceived parental favoritism and the parenting style score was found. Relative to self-description, participants were divided following gender social concepts. It seems evident that gender and birth order modulate the way parents raise their offspring and the way children assess them; in this case suffering the influence of brotherhood
Pulsations in white dwarfs: Selected topics
No full textThis paper presents a very brief overview of the observed properties of g-mode pulsations in variable white dwarfs. We then discuss a few selected topics: Excitation mechanisms (kappa- and convection- mechanisms), and briefly the effect of a strong magnetic field (∼ 1 MG) on g-modes as recently found in a hot DQ (carbon-rich atmosphere) white dwarf. In the discussion of excitation mechanisms, a simple interpretation for the convection mechanism is given
Indoxyl Sulfate Induces Renal Fibroblast Activation through a Targetable Heat Shock Protein 90-Dependent Pathway
No full textIndoxyl sulfate (IS) accumulation occurs early during chronic kidney disease (CKD) progression and contributes to renal dysfunction by inducing fibrosis, inflammation, oxidative stress, and tissue remodeling. Renal toxicity of high IS concentrations (250 μM) has been widely explored, particularly in resident tubular and glomerular cells, while the effect of a moderate IS increase on kidneys is still mostly unknown. To define the effects of IS accumulation on renal fibroblasts, we first analyzed kidneys of C57BL/6 mice receiving IS (0.1%) in drinking water for 12 weeks. As a next step, we treated renal fibroblasts (NRK-49F) with IS (20 μM) with or without the HSP90 inhibitor 17-AAG (1 μM). In mouse kidneys, IS increased the collagen deposition and HSP90 and α-SMA expression (immunohistochemistry) in interstitial fibroblasts and caused tubular necrosis (histological H&E and picrosirius red staining). In NRK-49F cells, IS induced MCP1, TGF-β, collagen I, α-SMA, and HSP90 gene/protein expression and Smad2/3 pathway activation. IS had no effects on fibroblast proliferation and ROS production. 17-AAG counteracted IS-induced MCP1, TGF-β, collagen I, and α-SMA expression and Smad2/3 phosphorylation. Our study demonstrates that the IS increase promotes renal fibroblast activation by a HSP90-dependent pathway and indicates HSP90 inhibition as a potential strategy to restrain IS-induced kidney inflammation and fibrosis in CKD
Periodicities in the high-mass X-ray binary system RXJ0146.9+6121/LSI+61 235
No full textThe high-mass X-ray binary RX J0146.9+6121, with optical counterpart LS I+61°235 (V831 Cas), is an intriguing system on the outskirts of the open cluster NGC 663. It contains the slowest Be type X-ray pulsar known with a pulse period of around 1400 s and, primarily from the study of variation in the emission line profile of Hα, it is known to have a Be decretion disc with a one-armed density wave period of approximately 1240 d. Here we present the results of an extensive photometric campaign, supplemented with optical spectroscopy, aimed at measuring short time-scale periodicities. We find three significant periodicities in the photometric data at, in order of statistical significance, 0.34, 0.67 and 0.10 d. We give arguments to support the interpretation that the 0.34 and 0.10 d periods could be due to stellar oscillations of the B-type primary star and that the 0.67 d period is the spin period of the Be star with a spin axis inclination of 23+10−8 degrees. We measured a systemic velocity of −37.0 ± 4.3 km s−1 confirming that LS I+61°235 has a high probability of membership in the young cluster NGC 663 from which the system's age can be estimated as 20–25 Myr. From archival RXTE All Sky Monitor (ASM) data we further find ‘super’ X-ray outbursts roughly every 450 d. If these super outbursts are caused by the alignment of the compact star with the one-armed decretion disc enhancement, then the orbital period is approximately 330 d
Polyethylene glycol promotes autoxidation of cytochrome c
No full textCytochrome c (Cyt c) was rapidly oxidized by molecular oxygen in the presence, but not absence of PEG. The redox potential of heme c was determined by the potentiometric titration to be +236 ± 3 mV in the absence of PEG, which was negatively shifted to +200 ± 4 mV in the presence of PEG. The underlying the rapid oxidation was explored by examining the structural changes in Cyt c in the presence of PEG using UV–visible absorption, circular dichroism, resonance Raman, and fluorescence spectroscopies. These spectroscopic analyses suggested that heme oxidation was induced by a modest tertiary structural change accompanied by a slight shift in the heme position (<1.0 Å) rather than by partial denaturation, as is observed in the presence of cardiolipin. The near-infrared spectra showed that PEG induced dehydration from Cyt c, which triggered heme displacement. The primary dehydration site was estimated to be around surface-exposed hydrophobic residues near the heme center: Ile81 and Val83. These findings and our previous studies, which showed that hydrated water molecules around Ile81 and Val83 are expelled when Cyt c forms a complex with CcO, proposed that dehydration of these residues is functionally significant to electron transfer from Cyt c to CcO
The evolutionary stage of an RRs star SX Phe
No full textThe evolutionary stage for a short period variable SX Phe was investigated. It was assumed that SX Phe is a mixed star with low metal abundance in which the material was mixed after the star evolved off the main sequence, and is in the second hydrogen burning stage. The validity of this hypothesis was examined by constructing two evolutionary sequences with (X,Z,M/solar mass) = (0.5,0.004,0.75) and (0.5,0.001,0.70) in the hydrogen burning phase and computed the pulsation period. Agreement between theoretical results and observational data was sufficient to conclude that the mixed model is actually adequate for SX Phe. The applicability of this model to other RRs stars is briefly discussed
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