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Search Results: 1 - 10 of 223823 matches for " R Murua "
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Ecología y evolución de hantavirus en el Cono Sur de América
Murua,R; Padula,P;
Archivos de medicina veterinaria , 2004, DOI: 10.4067/S0301-732X2004000100001
Abstract: hantavirus are associated with a single primary rodent host of the familiy muridae in three sub families, two of them murinae and arvicolinae distributed in the paleartic region (europa, asia, china) and the sub family sigmodontinae in north, central and south america besides an arvicolinae genus (microtus) in north america. studies on the host and virus phylogeny show close similarities when are compared which implies that hantavirus are very ancient infectious agents which have coevolved with the rodent host. the history of earth, tectonic movements and climatic changes which affected the continents in the past are relevant to understand the host reservoir and its micro parasites current geographic distribution. this review provides historical biogeography of the sigmodontine rodents, phylogentic analyses of hantavirus, its molecular epidemiology and its geographical distribution in south america in order to sustain the proposal that the virus- rodent interaction has coevolved in the neartic before the family muridae was detached in subfamilies and before the sigmodontines rodents spread into the south american continent. it is described the existence of a large number of hantavirus lineages with small differences which make difficult to establish so far, well define species of hantavirus. an analisis between similarities and differences in the ecology and pathogenesis of two virus which have produced an important number of human cases in north america (sin nombre) and in the southern cone of america (virus andes) is discussed.
Ecología y evolución de hantavirus en el Cono Sur de América Ecology and evolution of hantavirus in the Southern Cone of America
R Murua,P Padula
Archivos de medicina veterinaria , 2004,
Abstract: Los hantavirus tienen huéspedes especie específicos pertenecientes a una familia común Muridae con tres sub familias, dos de ellas Murinae y Arvicolinae que se distribuyen en áreas geográficas de Europa Asia y Oceanía con un género Arvicolinae en América del Norte y la Sub familia Sigmodontinae en Centro América y Sudamérica. Estudios de la filogenia del huésped y el virus muestran fuertes similitudes al ser comparados, lo que sugiere una asociación de mucha más larga data con un proceso de coevolución entre el agente infeccioso y sus huéspedes roedores. La historia de la tierra y los procesos tectónicos y climáticos que afectaron al continente en épocas pretéritas son relevantes para comprender la actual distribución de los reservorios huéspedes y sus parásitos. Se entregan antecedentes biogeográficos de los roedores con la distribución geográfica de los hantavirus en Sudamérica, análisis filogenético de los virus, epidemiología molecular que sustentan la propuesta que el virus y el roedor han coevolucionado antes del momento de separarse la Familia Muridae en subfamilias (Murinae, Arvicolinae y Sigmodontinae) y anterior al ingreso de los roedores sigmodontinos al continente sudamericano. Se discute la dificultad en demarcar especie nueva de hantavirus y la existencia de varios linajes con diferencias peque as entre si para ser consideradas como especies virales. Se describen diferencias y similitudes entre las dos especies de hantavirus que más casos han producido en América del Norte (virus Sin Nombre) y en el Cono Sur de de América (Virus Andes). Hantavirus are associated with a single primary rodent host of the familiy Muridae in three sub families, two of them Murinae and Arvicolinae distributed in the Paleartic Region (Europa, Asia, China) and the sub family Sigmodontinae in North, Central and South America besides an Arvicolinae genus (Microtus) in North America. Studies on the host and virus phylogeny show close similarities when are compared which implies that hantavirus are very ancient infectious agents which have coevolved with the rodent host. The history of earth, tectonic movements and climatic changes which affected the continents in the past are relevant to understand the host reservoir and its micro parasites current geographic distribution. This review provides historical biogeography of the sigmodontine rodents, phylogentic analyses of hantavirus, its molecular epidemiology and its geographical distribution in South America in order to sustain the proposal that the virus- rodent interaction has coevolved in the Neartic before the Fa
A new species of whipworm from a south american hystricomorph rodent
Babero, B. B.;Murua, R. B.;
Memórias do Instituto Oswaldo Cruz , 1990, DOI: 10.1590/S0074-02761990000200012
Abstract: a new species of whipworm, trichuris robusti, is described from the cecum and large intestine of rodent, ctnomys robusti, collected in northern chile. the nematode shows close affinityto t. bradleyi and t. chilensis, both having been described from chile but because of the possession of ceertain specific morphological chareacters, particularly the disposition of the proximal cloacal tube, could not be assigned to either of them. a key is presented to some of the trichuris species reported from hystricomorph rodents in chile and the biographical significance of speciation of chilean trichurids is discussed.
El Uso de la Eritropoyetina en el Manejo de la Insuficiencia Cardíaca
Pablo Ryan Murua
Medicrit : Revista de Medicina Crítica , 2004, DOI: 10.5413/mrmc.2004.16.23
Abstract: Casi el 64% de los pacientes que acuden al nefrólogo por insuficiencia renal (IR), presentan además insuficiencia cardiaca (IC), y la mayoría de estos presentan también anemia. A esta conjunción de anemia, insuficiencia cardiaca e insuficiencia renal se le ha llamado síndrome anemia cardiorrenal (SACR), cuyos componentes cierran un circulo vicioso. Cada uno de ellos es capaz de producir o empeorar los otros dos. La anemia se encuentra de un tercio de la mitad de los pacientes con insuficiencia cardiaca y puede producir y/o empeorar a esta, aumentar la mortalidad, hospitalización, y la malnutrición. Además la anemia se asocia con un deterioro de la función renal e insuficiencia renal, causando una progresión más rápida hacia la diálisis en los pacientes con anemia que en los pacientes sin anemia. El control subóptimo de la insuficiencia cardiaca puede llevar a un deterioro de la función renal y a anemia. La insuficiencia renal cronica puede causar anemia y empeorar la insuficiencia cardiaca...
An efficient algorithm for computing the Baker-Campbell-Hausdorff series and some of its applications
Fernando Casas,Ander Murua
Physics , 2008, DOI: 10.1063/1.3078418
Abstract: We provide a new algorithm for generating the Baker--Campbell--Hausdorff (BCH) series $Z = \log(\e^X \e^Y)$ in an arbitrary generalized Hall basis of the free Lie algebra $\mathcal{L}(X,Y)$ generated by $X$ and $Y$. It is based on the close relationship of $\mathcal{L}(X,Y)$ with a Lie algebraic structure of labeled rooted trees. With this algorithm, the computation of the BCH series up to degree 20 (111013 independent elements in $\mathcal{L}(X,Y)$) takes less than 15 minutes on a personal computer and requires 1.5 GBytes of memory. We also address the issue of the convergence of the series, providing an optimal convergence domain when $X$ and $Y$ are real or complex matrices.
Contribution of the Immigrant Population to Demographic and Spatial Dynamics of the Basque Country  [PDF]
Juan Ramón Murua, Bego?a Eguía
Natural Science (NS) , 2015, DOI: 10.4236/ns.2015.77038
Abstract: The twenty-first century begins with a rupture of the migratory pattern in the Basque Country, a region located in the north of Spain, transforming it from a community which exports its population to one which receives it. Despite the current economic crisis, the Basque Country continues to be a destination for foreigners, now in many cases coming from other Spanish regions most affected by this crisis. Given the quantitative and qualitative importance of these migration flows, in this research we analyze the contribution of immigrants to the demographic dynamics of the Basque Country. By also identifying their patterns of spatial localization, we examine their contribution to the correction or accentuation of regional imbalances in the population distribution. The results reveal that the demographic recovery rests primarily on contributions of this immigrant population, a population which also promotes the rejuvenation of an aging society, although it is far from correcting regional imbalances and may contribute to accentuating them.
Habitat utilization of two muroid species in relation to population outbreaks in southern temperate forests of Chile
GONZALEZ,LUZ A; MURUA,ROBERTO; JOFRE,CECILIA;
Revista chilena de historia natural , 2000, DOI: 10.4067/S0716-078X2000000300012
Abstract: large-scale outbreaks of two species of rodents (oligoryzomys longicaudatus and abrothrix olivaceus) in response to a large increase in food resources in san martin experimental preserve and in the peulla area of the vicente perez rosales national park, were observed during fruiting and seedling of arborescent bamboo (chusquea spp.). this unique phenomenon enabled the analysis of the effect of increased density on patterns of habitat use by these rodent species with mark-recapture grids in each area. vegetation analysis was performed at three strata at each capture site. associations between habitat variables and rodents presence or absence was assessed by using a logistic regressions. habitat preference was strongly influenced by population density. vegetation variables were important predictors for the presence of these rodent species only in years of low numbers. the results corroborate the predictions of the fretwell-lucas model of habitat selection
Habitat utilization of two muroid species in relation to population outbreaks in southern temperate forests of Chile Uso del hábitat por dos especies de múridos en respuesta a un aumento poblacional (ratada) en los bosques templados del sur de Chile
LUZ A GONZALEZ,ROBERTO MURUA,CECILIA JOFRE
Revista chilena de historia natural , 2000,
Abstract: Large-scale outbreaks of two species of rodents (Oligoryzomys longicaudatus and Abrothrix olivaceus) in response to a large increase in food resources in San Martin Experimental Preserve and in the Peulla area of the Vicente Perez Rosales National Park, were observed during fruiting and seedling of arborescent bamboo (Chusquea spp.). This unique phenomenon enabled the analysis of the effect of increased density on patterns of habitat use by these rodent species with mark-recapture grids in each area. Vegetation analysis was performed at three strata at each capture site. Associations between habitat variables and rodents presence or absence was assessed by using a logistic regressions. Habitat preference was strongly influenced by population density. Vegetation variables were important predictors for the presence of these rodent species only in years of low numbers. The results corroborate the predictions of the Fretwell-Lucas model of habitat selection
Error analysis of splitting methods for the time dependent Schrodinger equation
Sergio Blanes,Fernando Casas,Ander Murua
Physics , 2010, DOI: 10.1137/100794535
Abstract: A typical procedure to integrate numerically the time dependent Schr\"o\-din\-ger equation involves two stages. In the first one carries out a space discretization of the continuous problem. This results in the linear system of differential equations $i du/dt = H u$, where $H$ is a real symmetric matrix, whose solution with initial value $u(0) = u_0 \in \mathbb{C}^N$ is given by $u(t) = \e^{-i t H} u_0$. Usually, this exponential matrix is expensive to evaluate, so that time stepping methods to construct approximations to $u$ from time $t_n$ to $t_{n+1}$ are considered in the second phase of the procedure. Among them, schemes involving multiplications of the matrix $H$ with vectors, such as Lanczos and Chebyshev methods, are particularly efficient. In this work we consider a particular class of splitting methods which also involves only products $Hu$. We carry out an error analysis of these integrators and propose a strategy which allows us to construct different splitting symplectic methods of different order (even of order zero) possessing a large stability interval that can be adapted to different space regularity conditions and different accuracy ranges of the spatial discretization. The validity of the procedure and the performance of the resulting schemes are illustrated on several numerical examples.
Splitting and composition methods in the numerical integration of differential equations
Sergio Blanes,Fernando Casas,Ander Murua
Mathematics , 2008,
Abstract: We provide a comprehensive survey of splitting and composition methods for the numerical integration of ordinary differential equations (ODEs). Splitting methods constitute an appropriate choice when the vector field associated with the ODE can be decomposed into several pieces and each of them is integrable. This class of integrators are explicit, simple to implement and preserve structural properties of the system. In consequence, they are specially useful in geometric numerical integration. In addition, the numerical solution obtained by splitting schemes can be seen as the exact solution to a perturbed system of ODEs possessing the same geometric properties as the original system. This backward error interpretation has direct implications for the qualitative behavior of the numerical solution as well as for the error propagation along time. Closely connected with splitting integrators are composition methods. We analyze the order conditions required by a method to achieve a given order and summarize the different families of schemes one can find in the literature. Finally, we illustrate the main features of splitting and composition methods on several numerical examples arising from applications.
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