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Search Results: 1 - 10 of 311585 matches for " Pedro J Chacon "
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Inhibition of RhoA GTPase and the subsequent activation of PTP1B protects cultured hippocampal neurons against amyloid β toxicity
Pedro J Chacon, Rosa Garcia-Mejias, Alfredo Rodriguez-Tebar
Molecular Neurodegeneration , 2011, DOI: 10.1186/1750-1326-6-14
Abstract: We show here that Aβ activates the RhoA GTPase by binding to p75NTR, thereby preventing the NGF-induced activation of protein tyrosine phosphatase 1B (PTP1B) that is required for neuron survival. We also show that the inactivation of RhoA GTPase and the activation of PTP1B protect cultured hippocampal neurons against the noxious effects of Aβ. Indeed, either pharmacological inhibition of RhoA with C3 ADP ribosyl transferase or the transfection of cultured neurons with a dominant negative form of RhoA protects cultured hippocampal neurons from the effects of Aβ. In addition, over-expression of PTP1B also prevents the deleterious effects of Aβ on cultured hippocampal neurons.Our findings indicate that potentiating the activity of NGF at the level of RhoA inactivation and PTP1B activation may represent a new means to combat the noxious effects of Aβ in Alzheimer's disease.According to the amyloid hypothesis, amyloid beta (Aβ) aggregates form deposits in the brain, the process that precipitates the different manifestations of Alzheimer's disease (AD) [1]. Consequently, most therapeutic approaches to treat AD centre on this peptide: on the one hand attempting to limit the production of Aβ or the formation of fibrils and aggregates [2,3], while on the other hand, favouring its clearance. Therapeutic approaches aimed at clearing Aβ plaques have received special attention, and methods for active or passive immunisation have proven effective in reducing Aβ content in the brain. Nevertheless, these strategies have failed to conclusively ameliorate or retard cognitive deterioration in AD patients [4,5].Another approach that could be considered involves blocking the signals induced by Aβ that provoke neuronal death. However, despite extensive studies into the effects of Aβ on neurons, our understanding of Aβ signalling remains fragmented, and a consistent framework for such processes has yet to be defined. Still, recent publications have reinforced the notion that Aβ interferes
Indicadores cardiovasculares em repouso e durante um teste incremental em jovens do sexo masculino
Rodrigues, Eduardo Quieroti;Sousa, Sergio de;Christofaro, Diego Giulliano Destro;Cardoso, Mauro Leandro;Castoldi, Robson Chacon;Campos, Eduardo Zapaterra;Balikian Júnior, Pedro;Freitas Júnior, Ismael Forte;
Revista Brasileira de Cineantropometria & Desempenho Humano , 2012, DOI: 10.5007/1980-0037.2012v14n1p32
Abstract: the present study compared blood glucose levels, heart rate (hr) at rest and during exercise, besides body composition between hypertensive and normotensive individuals. the sample consisted of 32 young males with an average age of 22.6 years. initially, the blood pressure was measured to split the sample into two groups: hypertensive and normotensive. subsequently, fasting blood glucose, bioelectrical impedance, anthropometry, and resting heart rate, heart rate during maximal effort test and recovery phase were measured. statistical analysis was composed of a student t test and two-way repeated measures analysis. the significance adopted was p = 0.05. the analyzed data showed that hypertensive patients have higher metabolic rates and hemodynamic values than normotensive individuals, which are indicators of cardiovascular risk.
Study of theoretical models for the liquid-vapor and metal-nonmetal transitions of alkali fluids
E. Chacon,J. P. Hernandez,P. Tarazona
Physics , 1995, DOI: 10.1103/PhysRevB.52.9330
Abstract: Theoretical models for the liquid-vapor and metal-nonmetal transitions of alkali fluids are investigated. Mean-field models are considered first but shown to be inadequate. An alternate approach is then studied in which each statistical configuration of the material is treated as inhomogeneous, with the energy of each ion being determined by its local environment. Nonadditive interactions, due to valence electron delocalization, are a crucial feature of the model. This alternate approach is implemented within a lattice-gas approximation which takes into account the observed mode of expansion in the materials of interest and which is able to treat the equilibrium density fluctuations. We have carried out grand canonical Monte Carlo simulations, for this model, which allow a unified, self-consistent, study of the structural, thermodynamic, and electronic properties of alkali fluids. Applications to Cs, Rb, K, and Na yield results in good agreement with observations.
Simple model for the phase coexistence and electrical conductivity of alkali fluids
P. Tarazona,E. Chacon,J. P. Hernandez
Physics , 1994, DOI: 10.1103/PhysRevLett.74.142
Abstract: We report the first theoretical model for the alkali fluids which yields a liquid-vapor phase coexistence with the experimentally observed features and electrical conductivity estimates which are also in accord with observations. We have carried out a Monte Carlo simulation for a lattice gas model which allows an integrated study of the structural, thermodynamic, and electronic properties of metal-atom fluids. Although such a technique is applicable to both metallic and nonmetallic fluids, non-additive interactions due to valence electron delocalization are a crucial feature of the present model.
Numerical modeling of fluid dynamics and heat transfer of glass flow in a short channel
Ovando Chacon, G. E.;Ovando Chacon, S. L.;Prince Avelino, J. C.;
Brazilian Journal of Chemical Engineering , 2010, DOI: 10.1590/S0104-66322010000400018
Abstract: a numerical investigation of laminar flow in a two-dimensional, cartesian flow that exits from a short channel with a backward-facing step is carried out in this work for the reynolds number range of 0.00054 < re < 54. we studied the steady state fluid dynamics, phase change and heat transfer of the flow. we analyzed the flow behavior occurring for different outflow velocities and three different configuration of the step. the incompressible working fluid was glass. the temperature, streamline, phase change and pressure fields are obtained and analyzed as a function of position. in order to obtain a better understanding of the step angle influence on the fluid dynamics, we obtained the heat transfer flux rates and the axial velocity profiles.
Fragmentation vs. functionalization: chemical aging and organic aerosol formation
H. J. Chacon-Madrid ,N. M. Donahue
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2011,
Abstract: The transformation process that a carbon backbone undergoes in the atmosphere is complex and dynamic. Understanding all these changes for all the species in detail is impractical; however, choosing different molecules that resemble progressively higher stages of oxidation or aging and studying them can give us an insight into general characteristics and mechanisms. Here we determine secondary organic aerosol (SOA) mass yields of two sequences of molecules reacting with the OH radical at high NOx. Each sequence consists of species with similar vapor pressures, but a succession of oxidation states. The first sequence consists of n-pentadecane, n-tridecanal, 2-, 7-tridecanone, and pinonaldehyde. The second sequence consists of n-nonadecane, n-heptadecanal and cis-pinonic acid. Oxidized molecules tend to have lower relative SOA mass yields; however, oxidation state alone was not enough to predict how efficiently a molecule forms SOA. Certain functionalities are able to fragment more easily than others, and even the position of these functionalities on a molecule can have an effect. n-Alkanes tend to have the highest yields, and n-aldehydes the lowest. n-Ketones have slightly higher yields when the ketone moiety is located on the side of the molecule and not in the center. In general, oxidation products remain efficient SOA sources, though fragmentation makes them less effective than comparable alkanes.
Terapia cognitivo-comportamental em grupo no transtorno obsessivo-compulsivo: um ensaio clínico
Chacon Priscila de J,Motta Márcia M,Belloto Cristina
Revista Brasileira de Psiquiatria , 2003,
Some ideas on nonlinear musical analysis
R. Colucci,G. R. Chacon,J. S. Leguizamon C.
Applied Mathematical Sciences , 2013,
Abstract: In this article we use time series analysis methods such as recurrencequantification analysis, estimation of the correlation dimensionand Liapunov exponents to study three different musical compositions.The results suggest a different level of complexity and chaoticity withrespect to the degree of freedom of the composition style.
Manifestation of charged and strained graphene layers in the Raman response of graphite intercalation compounds
J. C. Chacon-Torres,L. Wirtz,T. Pichler
Physics , 2013, DOI: 10.1021/nn403885k
Abstract: We present detailed multi frequency resonant Raman measurements of potassium graphite intercalation compounds (GICs). From a well controlled and consecutive in-situ intercalation and high temperature de-intercalation approach the response of each stage up to stage VI is identified. The positions of the G and 2D lines as a function of staging depend on the charge transfer from K to the graphite layers and on the lattice expansion. Ab-initio calculations of the density and the electronic band-structure demonstrate that most (but not all) of the transferred charge remains on the graphene sheets adjacent to the intercalant layers. This leads to an electronic decoupling of these "outer" layers from the ones sandwiched between carbon layers and consequently to a decoupling of the corresponding Raman spectra. Thus higher stage GICs offer the possibility to measure the vibrations of single, double, and multi-layer graphene under conditions of biaxial strain. This strain can additionally be correlated to the in-plane lattice constants of GICs determined by x-ray diffraction. The outcome of this study demonstrates that Raman spectroscopy is a very powerful tool to identify local internal strain in pristine and weakly charged single and few-layer graphene and their composites, yielding even absolute lattice constants.
Mexican-Americans: Population Patterns; Educational Attainment
Yamilette Chacon
Sociation Today , 2005,
Abstract: Hispanics are the fastest growing and largest minority group in the United States. Comparing data from 1994 and 2004, it is shown that 59% of the Hispanic population in the United States is of Mexican origin. Educational attainment of Mexican-Americans is rapidly increasing in the second and third generations.
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