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Search Results: 1 - 10 of 485840 matches for " Irene Hernández-García "
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Dominant transport pathways in an atmospheric blocking event
Enrico Ser-Giacomi,Ruggero Vasile,Irene Recuerda,Emilio Hernández-García,Cristóbal López
Physics , 2015, DOI: 10.1063/1.4928704
Abstract: A Lagrangian flow network is constructed for the atmospheric blocking of eastern Europe and western Russia in summer 2010. We compute the most probable paths followed by fluid particles which reveal the {\it Omega}-block skeleton of the event. A hierarchy of sets of highly probable paths is introduced to describe transport pathways when the most probable path alone is not representative enough. These sets of paths have the shape of narrow coherent tubes flowing close to the most probable one. Thus, even when the most probable path is not very significant in terms of its probability, it still identifies the geometry of the transport pathways.
Quasiperiodic Patterns in Boundary-Modulated Excitable Waves
Irene Sendi?a-Nadal,Vicente Pérez-Mu?uzuri,Víctor M. Eguíluz,Emilio Hernández-García,Oreste Piro
Physics , 2000, DOI: 10.1103/PhysRevE.64.046208
Abstract: We investigate the impact of the domain shape on wave propagation in excitable media. Channelled domains with sinusoidal boundaries are considered. Trains of fronts generated periodically at an extreme of the channel are found to adopt a quasiperiodic spatial configuration stroboscopically frozen in time. The phenomenon is studied in a model for the photo-sensitive Belousov-Zabotinsky reaction, but we give a theoretical derivation of the spatial return maps prescribing the height and position of the successive fronts that is valid for arbitrary excitable reaction-diffusion systems.
Current management of gastric cancer Situación actual en el tratamiento del cáncer gástrico
Antonio Viúdez-Berral,Coro Miranda-Murua,Fernando Arias-de-la-Vega,Irene Hernández-García
Revista Espa?ola de Enfermedades Digestivas , 2012,
Abstract: Gastric cancer is a disease with high incidence and mortality in our population. The prognosis of patients with this disease is closely related to the neoplasm stage at diagnosis, including the following characteristics of the tumor: extension into the gastric wall thickness, spread to locoregional lymph nodes and the ability to generate distant metastases, as described by the TNM classification. For localized tumors characterized only by invasion of mucosa or submucosa at diagnosis, survival at 5 years is between 70 and 95% with exclusive surgical management; however, when extension into the gastric wall is higher and/or there is locoregional nodal involvement, survival decreases to 20-30% at 5 years. Currently, at high-volume centers, the extent of gastrectomy is individualized based on several parameters, which in an increasing number of cases allows a total gastrectomy with D2 lymphadenectomy and preservation of the spleen and pancreas. This improved procedure increases the chance of R0 surgery and improves the relationship between resected and affected lymph nodes, resulting in a decreased risk of the long-term locoregional recurrence. To improve these results, different therapeutic strategies combining chemotherapy or chemoradiotherapy with surgery have been tested. Previously, the Intergroup 0116 clinical trial, published in 2001, which changed clinical practice in the United States, showed that adjuvant chemoradiotherapy improved survival (from 26 to 37 months overall survival) of these patients. In Europe, perioperative chemotherapy has been considered the standard treatment, since the publication of two randomized phase III trials showed an increase at 5 years survival in the group treated with chemotherapy. El cáncer gástrico es un tumor de alta incidencia y mortalidad en nuestro medio, y su pronóstico está íntimamente relacionado con la situación neoplásica al diagnóstico, que incluye su extensión en el grosor de la pared gástrica, sobre los ganglios linfáticos locorregionales y su capacidad de generar metástasis a distancia, extensión basada en la clasificación TNM. En aquellos tumores localizados al diagnóstico, caracterizados por la invasión únicamente de mucosa-submucosa, la supervivencia a 5 a os se establece entre el 70 y el 95% con manejo quirúrgico exclusivo, sin embargo, cuando la extensión en la pared es mayor y/o existe afectación ganglionar locorregional, la supervivencia disminuye al 20-30% a 5 a os. Actualmente en centros con alto volumen de pacientes, la extensión de la gastrectomía se individualiza en función de varios parámet
Current management of gastric cancer
Viúdez-Berral,Antonio; Miranda-Murua,Coro; Arias-de-la-Vega,Fernando; Hernández-García,Irene; Artajona-Rosino,Alicia; Díaz-de-Lia?o,álvaro; Vera-García,Ruth;
Revista Espa?ola de Enfermedades Digestivas , 2012, DOI: 10.4321/S1130-01082012000300006
Abstract: gastric cancer is a disease with high incidence and mortality in our population. the prognosis of patients with this disease is closely related to the neoplasm stage at diagnosis, including the following characteristics of the tumor: extension into the gastric wall thickness, spread to locoregional lymph nodes and the ability to generate distant metastases, as described by the tnm classification. for localized tumors characterized only by invasion of mucosa or submucosa at diagnosis, survival at 5 years is between 70 and 95% with exclusive surgical management; however, when extension into the gastric wall is higher and/or there is locoregional nodal involvement, survival decreases to 20-30% at 5 years. currently, at high-volume centers, the extent of gastrectomy is individualized based on several parameters, which in an increasing number of cases allows a total gastrectomy with d2 lymphadenectomy and preservation of the spleen and pancreas. this improved procedure increases the chance of r0 surgery and improves the relationship between resected and affected lymph nodes, resulting in a decreased risk of the long-term locoregional recurrence. to improve these results, different therapeutic strategies combining chemotherapy or chemoradiotherapy with surgery have been tested. previously, the intergroup 0116 clinical trial, published in 2001, which changed clinical practice in the united states, showed that adjuvant chemoradiotherapy improved survival (from 26 to 37 months overall survival) of these patients. in europe, perioperative chemotherapy has been considered the standard treatment, since the publication of two randomized phase iii trials showed an increase at 5 years survival in the group treated with chemotherapy.
Purification, Immobilization and Characterization of Lipase Isoenzyme from Aspergillus niger with C8 Magnetic Particles  [PDF]
Samanta Hernández-García, María Inmaculada García-García, Francisco García-Carmona
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.57075
Abstract:

The purification of a lipase isoenzyme from an Aspergillus niger lipase A is reported in this manuscript. Purification was carried out in a simple adsorption step, in which the lipase was offered at low ionic strength to the commercially available C8 modified magnetic particles, MaKProt C8. When the isoenzyme was desorbed with a 0.2% solution of Triton X-100, the SDS-PAGE gel showed a single pure band with a molecular weight of 35 KDa. The purified fraction showed 66.75-fold purification compared with the crude extract. The pure fraction was characterized along with the crude extract and the lipase adsorbed on the MaKProt C8. The purified and the adsorbed lipase showed better activity for the tested substrates (p-nitrophenyl acetate, decanoate, myristate and palmitate) than the crude extract, the preferred substrates being myristate (26.7 μmol·min-1·mg-1) and decanoate (17.4 μmol·min-1·mg-1), respectively. The temperature and pH profiles showed no change for the three enzymes, the optimum temperature being 37°C and the best pH 7.0.

Hydrolysis of Trivalent Holmium in Aqueous Solutions of 2 M Ionic Strength by Spectrophotometric and Potentiometric Methods  [PDF]
Miguel Angel Hernández-García, Hilario López-González, Alberto Rojas-Hernández
Advances in Materials Physics and Chemistry (AMPC) , 2015, DOI: 10.4236/ampc.2015.55017
Abstract: The first hydrolysis constants of trivalent holmium in 2 M NaClO4 and 2 M NaCl at 303 K and in CO2 free conditions were determined. The pCH borderlines of precipitation and first hydrolysis were determined by means of a spectrophotometric method and last one with the program SQUAD. Independently, the stability constant for the first hydrolytic species was determined, by means of potentiometric pH titrations whose data were treated with the program SUPERQUAD. The hydrolysis constants obtained were: \"\"?and \"\". These values attained by both methods are the same. The log10β1,Cl constants for the species HoCl2+ was also calculated for 2 M ionic strength and 303 K from the hydrolysis constant obtained in both perchlorate and chloride media. This value was logβ1,Cl = -0.56.
Seasonal and regional characterization of horizontal stirring in the global ocean
I. Hernández-Carrasco,C. López,E. Hernández-García,A. Turiel
Physics , 2011, DOI: 10.1029/2012JC008222
Abstract: Recent work on Lagrangian descriptors has shown that Lyapunov Exponents can be applied to observed or simulated data to characterize the horizontal stirring and transport properties of the oceanic flow. However, a more detailed analysis of regional dependence and seasonal variability was still lacking. In this paper, we analyze the near-surface velocity field obtained from the Ocean general circulation model For the Earth Simulator (OFES) using Finite-Size Lyapunov Exponents (FSLE). We have characterized regional and seasonal variability. Our results show that horizontal stirring, as measured by FSLEs, is seasonally-varying, with maximum values in Summer time. FSLEs also strongly vary depending on the region: we have first characterized the stirring properties of Northern and Southern Hemispheres, then the main oceanic basins and currents. We have finally studied the relation between averages of FSLE and some Eulerian descriptors such as Eddy Kinetic Energy (EKE) and vorticity (w) over the different regions.
Non-Steady wall-bounded flows of viscoelastic fluids under periodic forcing
Anier Hernández-García,Antonio Fernández-Barbero,Oscar Sotolongo-Costa
Physics , 2013, DOI: 10.1007/s13538-014-0211-0
Abstract: The problem of oscillating flows inside pipes under periodic forcing of viscoelastic fluids is addressed here. Starting from the linear Oldroyd-B model, a generalized Darcy's law is obtained in frequency domain and an explicit expression for the dependence of the dynamic permeability on fluid parameters and forcing frequency is derived. Previous results in both viscoelastic and Newtonian fluids are here shown to be particular cases of our results. On the basis of our calculations, a possible explanation for the observed damping of local dynamic response as the forcing frequency increases is given. Good fitting with recent experimental studies of wave propagation in viscoelastic media is here exhibited. Sound wave propagation in viscoelastic media flowing inside straight pipes is investigated. In particular, we obtain the local dynamic response for weakly compressible flows.
Extracting directed information flow networks: an application to genetics and semantics
A. P. Masucci,A. Kalampokis,V. M. Eguíluz,E. Hernández-García
Physics , 2010, DOI: 10.1103/PhysRevE.83.026103
Abstract: We introduce a general method to infer the directional information flow between populations whose elements are described by n-dimensional vectors of symbolic attributes. The method is based on the Jensen-Shannon divergence and on the Shannon entropy and has a wide range of application. We show here the results of two applications: first extracting the network of genetic flow between the meadows of the seagrass Poseidonia Oceanica, where the meadow elements are specified by sets of microsatellite markers, then we extract the semantic flow network from a set of Wikipedia pages, showing the semantic channels between different areas of knowledge.
Diversity and Noise Effects in a Model of Homeostatic Regulation of the Sleep-Wake Cycle
Marco Patriarca ,Svetlana Postnova,Hans A. Braun,Emilio Hernández-García,Raúl Toral
PLOS Computational Biology , 2012, DOI: 10.1371/journal.pcbi.1002650
Abstract: Recent advances in sleep neurobiology have allowed development of physiologically based mathematical models of sleep regulation that account for the neuronal dynamics responsible for the regulation of sleep-wake cycles and allow detailed examination of the underlying mechanisms. Neuronal systems in general, and those involved in sleep regulation in particular, are noisy and heterogeneous by their nature. It has been shown in various systems that certain levels of noise and diversity can significantly improve signal encoding. However, these phenomena, especially the effects of diversity, are rarely considered in the models of sleep regulation. The present paper is focused on a neuron-based physiologically motivated model of sleep-wake cycles that proposes a novel mechanism of the homeostatic regulation of sleep based on the dynamics of a wake-promoting neuropeptide orexin. Here this model is generalized by the introduction of intrinsic diversity and noise in the orexin-producing neurons, in order to study the effect of their presence on the sleep-wake cycle. A simple quantitative measure of the quality of a sleep-wake cycle is introduced and used to systematically study the generalized model for different levels of noise and diversity. The model is shown to exhibit a clear diversity-induced resonance: that is, the best wake-sleep cycle turns out to correspond to an intermediate level of diversity at the synapses of the orexin-producing neurons. On the other hand, only a mild evidence of stochastic resonance is found, when the level of noise is varied. These results show that disorder, especially in the form of quenched diversity, can be a key-element for an efficient or optimal functioning of the homeostatic regulation of the sleep-wake cycle. Furthermore, this study provides an example of a constructive role of diversity in a neuronal system that can be extended beyond the system studied here.
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