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Search Results: 1 - 10 of 561760 matches for " Fernández-Pérez M "
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Classification of holomorphic foliations on Hopf manifolds
Maurício Corrêa,Arturo Fernández-Pérez,Antonio M. Ferreira
Mathematics , 2015,
Abstract: We classify nonsingular holomorphic foliations of dimension and codimension one on certain Hopf manifolds. More general, we prove that all nonsingular codimension one distributions on intermediary or generic Hopf manifolds are integrable and has holomorphic integral first. Also, we prove some results about singular holomorphic distributions on Hopf manifolds.
On non-Kupka points of codimension one foliations on $\mathbb{P}^3$
O. Calvo-Andrade,M. Corrêa,A. Fernández-Pérez
Mathematics , 2015,
Abstract: We study the singular set of a codimension one holomorphic foliations on $\mathbb{P}^3$. We find a local normal form of a codimension two component of the singular set that is not of Kupka type. We also determined the number of non-Kupka points immersed in a codimension two component of the singular set of a codimension one foliation on $\mathbb{P}^3$.
Una alterativa a la analgesia epidural en un paciente con vasculopatía periférica severa: catéter ciático proximal An alterative to the epidural analgesia in a patient with severe peripheral vasculopaty: proximal sciatic catheter
F. Mu?oz-González,A. Herrera,R. Gutiérrez-Pérez,M. Fernández-Pérez
Revista de la Sociedad Espa?ola del Dolor , 2008,
Abstract:
On Normal Forms for Levi-flat hypersurfaces with an Isolated Line Singularity
Arturo Fernández-Pérez
Mathematics , 2013, DOI: 10.1007/s11512-014-0198-3
Abstract: We prove the existence of normal forms for some local real-analytic Levi-flat hypersurfaces with an isolated line singularity. We also give sufficient conditions for that a Levi-flat hypersurface with a complex line as singularity to be a pullback of a real-analytic curve in C via a holomorphic function.
On Normal Forms of Singular Levi-Flat Real Analytic Hypersurfaces
Arturo Fernández-Pérez
Mathematics , 2010, DOI: 10.1007/s00574-011-0004-9
Abstract: Let $F(z)=\mathcal{R}e(P(z)) + h.o.t$ be such that $M=(F=0)$ defines a germ of real analytic Levi-flat at $0\in\mathbb{C}^{n}$, $n\geq{2}$, where $P(z)$ is a homogeneous polynomial of degree $k$ with an isolated singularity at $0\in\mathbb{C}^{n}$ and Milnor number $\mu$. We prove that there exists a holomorphic change of coordinate $\phi$ such that $\phi(M)=(\mathcal{R}e(h)=0)$ where $h(z)$ is a polynomial of degree $\mu+1$ and $j^{k}_{0}(h)=P$.
On Levi-flat hypersurfaces tangent to holomorphic webs
Arturo Fernández-Pérez
Mathematics , 2011,
Abstract: We investigate germs of real analytic Levi-flat hypersurfaces tangent to germs of codimension one holomorphic webs. We introduce the notion of first integrals for local webs. In particular, we prove that a $k$-web with finitely many invariant analytic subvarieties through the origin tangent to a Levi-flat hypersurface has a holomorphic first integral.
Genetic Algorithm for Arbitrage with More than Three Currencies  [PDF]
Adrián Fernández-Pérez, Fernando Fernández-Rodríguez, Simón Sosvilla-Rivero
Technology and Investment (TI) , 2012, DOI: 10.4236/ti.2012.33025
Abstract: We develop a genetic algorithm that is able to find the optimal sequence of exchange rates that maximizes arbitrage profits with more than three currencies, being both the triangular arbitrage and the direct exchange rate two special cases of the proposed algorithm. Applying the algorithm to the most traded currencies, we find average profits ranking from 4.5083% to 0.3162% for changing 1 USD for EUR with respect to the direct exchange rate, for different transaction costs, during the period October 2000-April 2012. Our results also suggest that the arbitrage profits increased just after the subprime crisis in summer of 2007 and that they are higher when the market is less liquid.
Influence of Vitamin D-Related Gene Polymorphisms (CYP27B and VDR) on the Response to Interferon/Ribavirin Therapy in Chronic Hepatitis C
Elena García-Martín, José A. G. Agúndez, María L. Maestro, Avelina Suárez, Marta Vidaurreta, Carmen Martínez, Cristina Fernández-Pérez, Luis Ortega, José M. Ladero
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074764
Abstract: Background and Aims Vitamin D exerts immunomodulatory effects on the host response against infection with hepatitis C virus (HCV). This study was performed to assess the putative influence of polymorphisms in vitamin D-related genes on the response to antiviral therapy in patients with chronic hepatitis C (CHC). Methods Single nucleotide polymorphisms (SNPs) in CYP27B-1260 gene promoter (rs10877012AC) and in vitamin D receptor (VDR) gene rs2228570TC, rs1544410CT, rs7975232AC and rs731236AT were analyzed in a cohort of 238 Caucasian CHC patients treated with pegylated interferon (Peg-IFN) plus ribavirin (RBV). Multivariate analyses were performed to exclude confounding effects of well-known baseline predictors of response to therapy (HCV genotype and load, IL28B genotype, age, and GGT and serum cholesterol). Results Three SNPs at the VDR gene (rs1544410, rs7975232 and rs731236) were in strong linkage disequilibrium, with the CCA haplotype predicting therapeutic failure [Odds ratio 2.743; (95% C.I. 1.313–5.731), p = 0.007]. The carrier state of the VDR rs2228570 T allele was inversely related to the probability of therapeutic failure [Odds ratio 0.438; 95 C.I. (0.204–0.882), p = 0.021]. No relation existed between CYP27B-1260 rs10877012 polymorphism and response to therapy. The area under the operating curve (AUROC) based on the model including all variables significantly related to the response to therapy was 0.846 (95% confidence interval = 0.793–0.899). Conclusion VDR gene polymorphisms are independently related to the response to Peg-IFN+RBV therapy in chronic hepatitis C and could be used as complementary biomarkers of response when included in a prediction algorithm in association with demographic, virologic, biochemical and genetic traits.
Exploring hepatic hormone actions using a compilation of gene expression profiles
Nina St?hlberg, Roxana Merino, Luis Hernández, Leandro Fernández-Pérez, Albin Sandelin, P?r Engstr?m, Petra Tollet-Egnell, Boris Lenhard, Amilcar Flores-Morales
BMC Physiology , 2005, DOI: 10.1186/1472-6793-5-8
Abstract: Little similarity exists between liver transcript profiles regulated by 17-α-ethinylestradiol and those induced by the continuos infusion of bGH. On the other hand, strong correlations were found between both profiles and the female enriched transcript profile. Therefore, estrogens have feminizing effects in male rat liver which are different from those induced by GH. The similarity between bGH and T3 were limited to a small group of genes, most of which are involved in lipogenesis. An in silico promoter analysis of genes rapidly regulated by thyroid hormone predicted the activation of SREBPs by short-term treatment in vivo. It was further demonstrated that proteolytic processing of SREBP1 in the endoplasmic reticulum might contribute to the rapid actions of T3 on these genes.This report illustrates how a meta-analysis of multiple transcript profiles can be used to link knowledge concerning endocrine physiology to hormonally induced changes in gene expression. We conclude that both GH and estrogen are important determinants of gender-related differences in hepatic gene expression. Rapid hepatic thyroid hormone effects affect genes involved in lipogenesis possibly through the induction of SREBP1 proteolytic processing.The completion of human and rodent genome sequences [1-3] has brought the post-genomic era to the field of endocrine research. Detailed genetic maps of the main endocrine models can now be used to study the molecular basis of endocrine disease and the molecular mechanisms of hormone actions. The possibility to explore expression data of thousands of genes across multiple experimental paradigms promise to rapidly increase our understanding of biological systems [4,5]. The acquisition of experimental data at a genomic scale requires high throughput technologies such as DNA microarray analysis. Microarrays enable the simultaneous assessment of expression levels of tens of thousands of gene products in an ease to perform assay. Microarrays are especially at
Propiedades físico-mecánicas de algunas maderas nativas chilenas coníferas y latifoliadas por ultrasonido Physical and mechanical properties of some chilean softwoods and hardwoods using ultrasound
Erik Baradit,Peter Niemz,Arturo Fernández-Pérez
MADERAS : Ciencia y Tecnología , 2013,
Abstract: La utilización de técnicas no destructivas juega un papel importante y complementario en los procesos de caracterización de la madera. En este trabajo el objetivo fue evaluar algunas propiedades físico-mecánicas de maderas nativas chilenas por medio de ultrasonido y compararlas con ensayos mecánicos tradicionales de flexión. Las maderas seleccionadas fueron cuatro latifoliadas: tepa (Laureliopsis philipiana), olivillo (Aextoxicon punctatum), laurel (Laurelia sempervirens) y lenga (Nothofagus pumilio), y dos coníferas: alerce (Fitzroya cupressoides) y ma ío (Podocarpus nubigena). Para ésto, se utilizaron los equipos de ultrasonido Steinkamp BP5 y Panametric Epoch XT. Los resultados mostraron mayor anisotropía elástica para las latifoliadas que para las coníferas y una relativa simetría en las velocidades de propagación transversal y los módulos de corte a lo largo de las tres principales direcciones del árbol. También los valores medios de los módulos de elasticidad calculados por ultrasonido resultaron entre 25 y 47 % más altos que los medidos por ensayos mecánicos. The non-destructive techniques are a very important tool in the process of wood characterization and evaluation. In this work, the objective is the evaluation of physical and mechanical properties of some native Chilean wood species by using the ultrasound techniques and their comparision with the results of typical mechanical tests. The selected woods were four hardwoods: tepa (Laureliopsis philipiana), olivillo (Aextoxicon punctatum), laurel (Laurelia sempervirens) and lenga (Nothofagus pumilio) and two softwoods: alerce (Fitzroya cupressoides) and ma ío (Podocarpus nubigena). The equipment used were two types of ultrasound generators: Steinkamp BP5 and Panametric Epoch XT. The results shown a higher anisotropy for hardwoods than for softwoods, and a relatively symmetry for transversal wave propagation velocities and for shear moduli of elasticity, along the principal directions of the tree. At the same time the mean values of Young moduli of elasticity (MOE) obtained by using the ultrasound equipments were a 25-47 % higher than the same moduli measured by mechanical tests.
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