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Search Results: 1 - 10 of 226384 matches for " Rodolfo R; "
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De la "Nación Católica" a la "República Pluricultural" en América Latina. Algunas consideraciones históricas1
de Roux,Rodolfo R.;
Memorias: Revista Digital de Historia y Arqueología desde el Caribe , 2012,
Abstract: his text is a historical analysis of how the "catholic nation" in latin america was the result of a difficult construction process in the nineteenth century and first half of the twentieth century, and on the transition from "catholic nation" to "multicultural republic" in many latin american countries in the last third of the twentieth century.
The Olivo-cerebellar System: A Key to understanding the functional significance of intrinsic oscillatory brain properties
Rodolfo R. Llinas
Frontiers in Neural Circuits , 2013, DOI: 10.3389/fncir.2013.00096
Abstract: The reflexological view of brain function (Sherrington 1906) has played a crucial role in defining both the nature of connectivity and the role of the synaptic interactions among neuronal circuits. One implicit assumption of this view, however, has been that CNS function is fundamentally driven by sensory input. This view was questioned as early as the beginning of the last century when a possible role for intrinsic activity in CNS function was proposed by Thomas Graham Brow (Brown 1911; Brown 1914). However, little progress was made in addressing intrinsic neuronal properties in vertebrates until the discovery of calcium conductances in vertebrate central neurons leading dendritic electroresponsiveness (Llinas and Hess 1976, Llinas and Sugimori 1980a and b) and subthreshold neuronal oscillation in mammalian inferior olive (IO) neurons (Llinas and Yarom 1981; Llinas and Yarom 1981).This happened in parallel with a similar set of findings concerning invertebrate neuronal system (Marder and Bucher 2001). The generalization into a more global view of intrinsic rhythmicity, at forebrain level, occurred initially with the demonstration that the thalamus has similar oscillatory properties (Llinas and Jahnsen 1982) and the ionic properties responsible for some oscillatory activity were, in fact, similar to those in the IO (Jahnsen and Llinas 1984; Llinas 1988). Thus lending support to the view that not only motricity, but cognitive properties, are organized as coherent oscillatory states (Pare, deCurtis et al. 1992; Singer 1993; Hardcastle 1997; Llinas, Ribary et al. 1998; Varela, Lachaux et al. 2001).
Edge Effects of Oil Pipeline Canopy Openings on Tree Community Structure and Dynamics in a Montane Atlantic Forest  [PDF]
Pablo J. F. Pena Rodrigues, Leticia R. Melo, Rodolfo C. R. de Abreu, Mariana A. Iguatemy
Journal of Geoscience and Environment Protection (GEP) , 2016, DOI: 10.4236/gep.2016.47014
Abstract: The Atlantic forest has historically been severely deforested, and only fragments currently remain that are subject to a wide variety of anthropogenic impacts, including edge effects that can cause structural and functional degradation. The Tinguá Biological Reserve-RJ comprises approximately 26,000 hectares of well-preserved Atlantic Forest, but it is subject to impacts caused by two canopy openings along oil pipelines. Comparisons were made between pipeline edges and forest interiors to evaluate edge effects on the structure and dynamics of those tree communities. Tree densities were higher along forest edges, apparently increasing over time. Tree basal areas, on the other hand, have decreased along edges due to higher mortality rates. Linear canopy opening edges showed higher densities of small trees, while the interior had more very large trees, indicating changes in successional processes and community structural patterns due to edge effects.
Palaeopathological Survey of a Population of Mapusaurus (Theropoda: Carcharodontosauridae) from the Late Cretaceous Huincul Formation, Argentina
Phil R. Bell, Rodolfo A. Coria
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0063409
Abstract: Paleoepidemiology (the study of disease and trauma in prehistoric populations) provides insight into the distribution of disease and can have implications for interpreting behavior in extinct organisms. A monospecific bonebed of the giant carcharodontosaurid Mapusaurus (minimum number of individuals = 9) from the Ca?adón del Gato site, Neuquén Province, Argentina (Cenomanian) provides a rare opportunity to investigate disease within a single population of this important apex predator. Visual inspection of 176 skeletal elements belonging to a minimum of nine individuals yielded a small number of abnormalities on a cervical vertebra, two ribs, pedal phalanx, and an ilium. These are attributed to traumatic (two cases), infectious (two cases) and anomalous (one case) conditions in a minimum of one individual. The emerging picture for large theropod (abelisaurids, allosaurids, carcharodontosaurids, tyrannosaurids) populations suggests that 1) osseous abnormalities were relatively rare (7–19% of individuals) but consistently present, and 2) trauma was a leading factor in the frequency of pathological occurrences, evidence of an active, often perilous lifestyle.
Frequency-pattern functional tomography of magnetoencephalography data allows new approach to the study of human brain organization
Rodolfo R. Llinás,Mikhail N. Ustinin
Frontiers in Neural Circuits , 2014, DOI: 10.3389/fncir.2014.00043
Abstract: A method based on a set of new theorems for the analysis of multichannel time series is described, based on precise Fourier transform and coherence analysis of the restored signals from a detailed set of frequency components. Magnetic field recordings of spontaneous and evoked activity by means of magnetic encephalography demonstrated that multichannel precise Fourier spectrum contains a very large set of harmonics with high coherence. The inverse problem can be solved with great precision based on coherent harmonics, so the technique is a promising platform of general analysis in brain imaging. The analysis method makes it possible to reconstruct sites and timing of electrical activity generated by both spontaneous and evoked brain function at different depths in the brain in the millisecond time range.
A model for shock wave chaos
Aslan Kasimov,Luiz Faria,Rodolfo R. Rosales
Physics , 2012, DOI: 10.1103/PhysRevLett.110.104104
Abstract: We propose the following model equation: \[u_{t}+1/2(u^{2}-uu_{s})_{x}=f(x,u_{s}), \] that predicts chaotic shock waves. It is given on the half-line $x<0$ and the shock is located at $x=0$ for any $t\ge0$. Here $u_{s}(t)$ is the shock state and the source term $f$ is assumed to satisfy certain integrability constraints as explained in the main text. We demonstrate that this simple equation reproduces many of the properties of detonations in gaseous mixtures, which one finds by solving the reactive Euler equations: existence of steady traveling-wave solutions and their instability, a cascade of period-doubling bifurcations, onset of chaos, and shock formation in the reaction zone.
Multirate integration of axisymmetric step-flow equations
Pak-Wing Fok,Rodolfo R. Rosales
Mathematics , 2008,
Abstract: We present a multirate method that is particularly suited for integrating the systems of Ordinary Differential Equations (ODEs) that arise in step models of surface evolution. The surface of a crystal lattice, that is slightly miscut from a plane of symmetry, consists of a series of terraces separated by steps. Under the assumption of axisymmetry, the step radii satisfy a system of ODEs that reflects the steps' response to step line tension and step-step interactions. Two main problems arise in the numerical solution of these equations. First, the trajectory of the innermost step can become singular, resulting in a divergent step velocity. Second, when a step bunching instability arises, the motion of steps within a bunch becomes very strongly stable, resulting in "local stiffness". The multirate method introduced in this paper ensures that small time steps are taken for singular and locally stiff components, while larger time steps are taken for the remaining ones. Special consideration is given to the construction of high order interpolants during run time which ensures fourth order accuracy of scheme for components of the solution sufficiently far away from singular trajectories.
Mardones R,Rodolfo; Mondaca A,Roberto; ávila R,Ricardo;
Revista chilena de radiología , 2002, DOI: 10.4067/S0717-93082002000400005
Abstract: we present two documented cases of patients with tyrosinemia type i (hepatorenal tyrosinemia) in infants. the most constant imaging findings in target organs: liver (hepatic cirrhosis), kidneys (nefromegaly) are described and compared with pathological findings in one case. in the presence of confusing clinical manifestations, radiological findings of hepatic cirrhosis in infants associated with renal involvement are almost diagnostic of this entity
Rodolfo Mardones R,Roberto Mondaca A,Ricardo ávila R
Revista Chilena de Radiología , 2002,
Abstract: Se presentan 2 casos documentados de lactantes portadores de Tirosinemia tipo I (Hepatorenal). Se describen los hallazgos imagenológicos principales de ella en los órganos blanco: Hígado (Cirrosis Hepática) y ri ones (Nefromegalia) y se confrontan con los de la anatomía patológica en un caso. En un lactante, con un cuadro clínico poco claro, el hallazgo imagenológico de cirrosis hepática sumado a un compromiso renal, deben hacer plantear el diagnóstico de tirosinemia We present two documented cases of patients with Tyrosinemia type I (Hepatorenal Tyrosinemia) in infants. The most constant imaging findings in target organs: Liver (Hepatic Cirrhosis), Kidneys (Nefromegaly) are described and compared with pathological findings in one case. In the presence of confusing clinical manifestations, radiological findings of hepatic cirrhosis in infants associated with renal involvement are almost diagnostic of this entity
Study of a model equation in detonation theory
Luiz M. Faria,Aslan R. Kasimov,Rodolfo R. Rosales
Physics , 2013,
Abstract: Here we analyze properties of an equation that we previously proposed to model the dynamics of unstable detonation waves [A. R. Kasimov, L. M. Faria, and R. R. Rosales. Model for shock wave chaos. Physical Review Letters, 110(10):104104, 2013]. The equation is \[ u_{t}+\frac{1}{2}\left(u^{2}-uu\left(0_{-},t\right)\right)_{x}=f\left(x,u\left(0_{-},t\right)\right),\quad x\le0,\quad t>0. \] It describes a detonation shock at $x=0$ with the reaction zone in $x<0$. We investigate the nature of the steady-state solutions of this nonlocal hyperbolic balance law, the linear stability of these solutions, and the nonlinear dynamics. We establish the existence of instability followed by a cascade of period-doubling bifurcations leading to chaos.
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