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Search Results: 1 - 10 of 474027 matches for " Marcelo A. Fernandez Vina "
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Psoriasis Patients Are Enriched for Genetic Variants That Protect against HIV-1 Disease
Haoyan Chen,Genki Hayashi,Olivia Y. Lai,Alexander Dilthey,Peter J. Kuebler,Tami V. Wong,Maureen P. Martin,Marcelo A. Fernandez Vina,Gil McVean,Matthias Wabl,Kieron S. Leslie,Toby Maurer,Jeffrey N. Martin,Steven G. Deeks,Mary Carrington,Anne M. Bowcock,Douglas F. Nixon,Wilson Liao
PLOS Genetics , 2012, DOI: 10.1371/journal.pgen.1002514
Abstract: An important paradigm in evolutionary genetics is that of a delicate balance between genetic variants that favorably boost host control of infection but which may unfavorably increase susceptibility to autoimmune disease. Here, we investigated whether patients with psoriasis, a common immune-mediated disease of the skin, are enriched for genetic variants that limit the ability of HIV-1 virus to replicate after infection. We analyzed the HLA class I and class II alleles of 1,727 Caucasian psoriasis cases and 3,581 controls and found that psoriasis patients are significantly more likely than controls to have gene variants that are protective against HIV-1 disease. This includes several HLA class I alleles associated with HIV-1 control; amino acid residues at HLA-B positions 67, 70, and 97 that mediate HIV-1 peptide binding; and the deletion polymorphism rs67384697 associated with high surface expression of HLA-C. We also found that the compound genotype KIR3DS1 plus HLA-B Bw4-80I, which respectively encode a natural killer cell activating receptor and its putative ligand, significantly increased psoriasis susceptibility. This compound genotype has also been associated with delay of progression to AIDS. Together, our results suggest that genetic variants that contribute to anti-viral immunity may predispose to the development of psoriasis.
A survey of freshwater gastropods in the Microrregi o Serrana of the State of Rio de Janeiro, Brazil
Thiengo Silvana C,Fernandez Monica A,Boaventura M Fernanda,Stortti Marcelo A
Memórias do Instituto Oswaldo Cruz , 1998,
A new media optimizer based on the mean-variance model
Fernandez, Pedro Jesus;Lauretto, Marcelo de Souza;Pereira, Carlos Alberto de Bragan?a;Stern, Julio Michael;
Pesquisa Operacional , 2007, DOI: 10.1590/S0101-74382007000300003
Abstract: in the financial markets, there is a well established portfolio optimization model called generalized mean-variance model (or generalized markowitz model). this model considers that a typical investor, while expecting returns to be high, also expects returns to be as certain as possible. in this paper we introduce a new media optimization system based on the mean-variance model, a novel approach in media planning. after presenting the model in its full generality, we discuss possible advantages of the mean-variance paradigm, such as its flexibility in modeling the optimization problem, its ability of dealing with many media performance indices - satisfying most of the media plan needs - and, most important, the property of diversifying the media portfolios in a natural way, without the need to set up ad hoc constraints to enforce diversification.
Structure of chalcogenide glasses by neutron diffraction
Gabriel Cuello,Andrea Piarristeguy,Alejandro Fernandez-Martinez,Marcelo Fontana,A. Pradel
Physics , 2008, DOI: 10.1016/j.jnoncrysol.2006.12.036
Abstract: The purpose of this work is to study the change in the structure of the Ge-Se network upon doping with Ag. The total structure factor S(Q) for two samples has been measured by neutron diffraction using the two-axis diffractometer dedicated to structural studies of amorphous materials, D4, at the Institut Laue Langevin. We have derived the corresponding radial distribution functions for each sample and each temperature, which gives us an insight about the composition and temperature dependence of the correlation distances and coordination numbers in the short-range. Our results are compatible with the presence of both GeSe4/2 tetrahedra and Se-Se bonds. The Ag atoms are linked to Se in a triangular environment. Numerical simulations allowing the identification of the main peaks in the total pair correlation functions have complemented the neutron diffraction measurements.
Fracture Mechanics Modelling of Cracked Aluminium Panel Repaired with Bonded Composite Circular Patch
D. Ouinas,A. Hebbar,J. Vina Olay
Journal of Applied Sciences , 2006,
Abstract: The process of repair of the structures by using bonded composite patch is an effectiveness and economical method to increase the service life of damaged structures. In this study, the finite element method is used to analyze the behaviour of a crack repaired by a patch by computing the stress intensity factor at the crack tip in mode I and mixed mode. The effects of the mechanical and geometrical properties of the patch on the fracture parameters are highlighted. The obtained results show that there is a considerable reduction of the asymptotic value of the stress intensity factor at the crack tip in the case of the use of the double symmetric patch compared with the single patch. Moreover, the good orientation of fibres having the highest mechanical characteristics compared to the crack growth influences considerably the reduction of the stress intensity factor. For the boron/epoxy patch, the orientation of fibres perpendicularly compared to the crack is four times larger than the orientation parallel with the crack. The adhesive properties must be optimized to increase the performance of the repaired structure by the reinforcement.
Time Storage Effect of the Resin on the Toughness of a Unidirectional Carbon Fibre
R. Zenasni,A. Hebbar,J. Vina olay
Journal of Applied Sciences , 2006,
Abstract: In the present study we investigate the effect of the time storage of the epoxy resin on the interlaminar fracture toughness of a three unidirectional carbon fibre. The interlaminar fracture behaviour was studied using the mode I, Double Cantilever Beam (DCB) test, the mode II, End Notched Flexure (ENF) test and a mixed mode bending (I/II) in order to determine the energy required for the initiation and growth of an artificial crack. The materials were made by a 32 stacking of unidirectional prepared carbon fibre. The matrix used was an epoxy of type (TGDMA) without a modification. The delamination energies of these three materials were compared in orders to characterize their mechanical properties.
Collective dynamics of excitons and polaritons in semiconductor nanostructures
A. Amo,D. Sanvitto,L. Vina
Physics , 2009, DOI: 10.1088/0268-1242/25/4/043001
Abstract: Time resolved photoluminescence is a powerful technique to study the collective dynamics of excitons and polaritons in semiconductor nanostructures. We present a two excitation pulses technique to induce the ultrafast and controlled quenching of the exciton emission in a quantum well. The depth of the dip is given by the magnitude of the warming of the carriers induced by the arrival of a laser pulse when an exciton population is already present in the sample. We use this technique to study the relaxation mechanisms of polaritons in semiconductor microcavities, which are of great importance to enhance the conditions for their condensation under non-resonant excitation. We also explore the dynamics of polariton fluids resonantly created in the lower polariton branch in a triggered optical parametric oscillator configuration, showing evidence of polariton superfluidity, and opening up the way to the real-time study of quantum fluids.
A New Approach to the Small Phylogeny Problem
Jakub Ková?,Broňa Brejová,Tomá? Vina
Quantitative Biology , 2010, DOI: 10.1007/978-3-642-23038-7_15
Abstract: In the small phylogeny problem we, are given a phylogenetic tree and gene orders of the extant species and our goal is to reconstruct all of the ancestral genomes so that the number of evolutionary operations is minimized. Algorithms for reconstructing evolutionary history from gene orders are usually based on repeatedly computing medians of genomes at neighbouring vertices of the tree. We propose a new, more general approach, based on an iterative local optimization procedure. In each step, we propose candidates for ancestral genomes and choose the best ones by dynamic programming. We have implemented our method and used it to reconstruct evolutionary history of 16 yeast mtDNAs and 13 Campanulaceae cpDNAs.
Goal-oriented incentive payment in CUDAM institution and variation in medical visit indicators in children under one and pregnant women
Marcelo Morales,Jorge Fernandez
Medwave , 2011,
Abstract: ntroduction: The establishment of National Integrated Health System in Uruguay from 2007 led to changes in the financing of the Collective Health Care Institutions (IAMC). They charge the National Health Fund (FONASA) for their partners from social security (SS) a health fee consists of: a) A risk-adjusted capita (94%)b) A component for compliance with performance (6%), depending on the fulfillment of three goals of care. Goal 1 is a component of the child under 1 year and a component of the pregnant woman. For both components were established institutional baseline (July 2007-September 2008) in the control patients in both age groups. This motif COMPLIANCE quarterly reports with a fee of $48/user FONASA/month for average baseline compliment. Las for children and pregnant women were monitored for IAMC CUDAM 64% and 59% respectively.This institution has 42,000 users, 95% derived from SS, featuring 45 births, 585 children <1 year and 405 pregnant women tested monthly.Objectives: Evaluate two years (July-September 2010):a) The mean percentages of compliance for children and pregnant CUDAM with medical controlb) Relationship between income through the FONASA insitucional for goal 1 and children and pregnant women in medical management during the quarter.Methods: a retrospective study of children and pregnant women with medical control CUDAM. In turn, each target has 6 indicators (N: children, F: females). Child: N1 and N2: derivation and acquisition of the newborn, N3: controls as a guideline, N4: current vaccination, N5: ultrasound hip and pregnant, N6: accreditation in good feeding practices for infants and young children and pregnant women. Pregnant woman: M1 controls as a guideline, M2: leaf perinatal information system, M3: HIV and VDRL performed, M4: uptake in 1 st quarter, M5 and M6: dental checkup during pregnancy and postpartum.Results: The mean percentages of compliance for children and pregnant women increased to 92% (164 additional children) and 88% (117 additional pregnant) respectively. Insitucional monthly income for the goal 1 was $1,915,200 (US$1 = $20).Average income/month was $1,637 and $2,364 per child and pregnant women respectively. We conclude that the target incentive payment of 1 allowed to significantly improve the indicators of child and maternal control of CUDAM.
Spin splitting in a polarized quasi-two-dimensional exciton gas
L. Vina,L. Munoz,E. Perez,J. Fernandez-Rossier,C. Tejedor,K. Ploog
Physics , 1996, DOI: 10.1103/PhysRevB.54.R8317
Abstract: We have observed a large spin splitting between "spin" $+1$ and $-1$ heavy-hole excitons, having unbalanced populations, in undoped GaAs/AlAs quantum wells in the absence of any external magnetic field. Time-resolved photoluminescence spectroscopy, under excitation with circularly polarized light, reveals that, for high excitonic density and short times after the pulsed excitation, the emission from majority excitons lies above that of minority ones. The amount of the splitting, which can be as large as 50% of the binding energy, increases with excitonic density and presents a time evolution closely connected with the degree of polarization of the luminescence. Our results are interpreted on the light of a recently developed model, which shows that, while intra-excitonic exchange interaction is responsible for the spin relaxation processes, exciton-exciton interaction produces a breaking of the spin degeneracy in two-dimensional semiconductors.
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