3,110 research outputs found
Industrias del Paleolítico antiguo en el valle medio del Guadalquivir
El trabajo responde al objetivo de participar en la reconstrucción de la secuencia paleolítica y geoarqueológica de la cuenca media y baja del Guadalquivir, tarea iniciada en la Universidad de Sevilla a principios de la década de los ochenta del pasado siglo por los Dres. Vallespí y Díaz del Olmo, y que continúa en la actualidad. El trabajo se ha centrado en el sector en que confluyen Genil y Guadalquivir, en el entorno de la localidad de Palma del Río, provincia de Córdoba (Andalucía, España). Se trata de una zona de vital importancia para el conocimiento de las primeras ocupaciones prehistóricas de nuestra región, pues a los materiales cuarcíticos que, procedentes de Sierra Morena, aporta el gran colector andaluz, utilizados en los modos de talla achelenses de toda la cuenca, se une el sílex que arrastra su principal afluente desde las cordilleras Béticas, empleado en los modos de talla adscritos al Paleolítico Medio
Capacitated Trees, Capacitated Routing, and Associated Polyhedra
We study the polyhedral structure of two related core combinatorial problems: the subtree cardinalityconstrained minimal spanning tree problem and the identical customer vehicle routing problem. For each of these problems, and for a forest relaxation of the minimal spanning tree problem, we introduce a number of new valid inequalities and specify conditions for ensuring when these inequalities are facets for the associated integer polyhedra. The inequalities are defined by one of several underlying support graphs: (i) a multistar, a "star" with a clique replacing the central vertex; (ii) a clique cluster, a collection of cliques intersecting at a single vertex, or more generally at a central" clique; and (iii) a ladybug, consisting of a multistar as a head and a clique as a body. We also consider packing (generalized subtour elimination) constraints, as well as several variants of our basic inequalities, such as partial multistars, whose satellite vertices need not be connected to all of the central vertices. Our development highlights the relationship between the capacitated tree and capacitated forest polytopes and a so-called path-partitioning polytope,and shows how to use monotone polytopes and a set of simple exchange arguments to prove that valid inequalities are facets
Dual-path state reconstruction scheme for propagating quantum microwaves and detector noise tomography
Quantum state reconstruction involves measurement devices that are usually
described by idealized models, but not known in full detail in experiments. For
weak propagating microwaves, the detection process requires linear amplifiers
which obscure the signal with random noise. Here, we introduce a theory which
nevertheless allows one to use these devices for measuring all quadrature
moments of propagating quantum microwaves based on cross-correlations from a
dual-path amplification setup. Simultaneously, the detector noise properties
are determined, allowing for tomography. We demonstrate the feasibility of our
novel concept by proof-of-principle experiments with classical mixtures of weak
coherent microwaves.Comment: 11 pages, 3 figure
Gliotransmitters travel in time and space.
The identification of the presence of active signaling between astrocytes and neurons in a process termed gliotransmission has caused a paradigm shift in our thinking about brain function. However, we are still in the early days of the conceptualization of how astrocytes influence synapses, neurons, networks, and ultimately behavior. In this Perspective, our goal is to identify emerging principles governing gliotransmission and consider the specific properties of this process that endow the astrocyte with unique functions in brain signal integration. We develop and present hypotheses aimed at reconciling confounding reports and define open questions to provide a conceptual framework for future studies. We propose that astrocytes mainly signal through high-affinity slowly desensitizing receptors to modulate neurons and perform integration in spatiotemporal domains complementary to those of neurons
Altitude and COVID-19 in Colombia : an updated analysis accounting for potential confounders
Q4Q2Pacientes con COVID-19We assessed the relationship between the altitude of municipalities and the incidence, mortality, and fatality from COVID-19 and excess of mortality in Colombia between 2020 and 2022. We conducted an ecologic study including all 1122 municipalities in Colombia and used categories of altitude as main independent variable. We fit multivariable regression models for incidence, mortality, fatality rates, and excess of mortality controlling for several variables at municipality level. There was a higher incidence rate, similar mortality rate and lower case-fatality rate for COVID-19 during 2020–2022 in municipalities in the upper category of altitude (>=2500 masl) compared to the lower category (<1000 masl). The excess of mortality was lower but not statistically different in municipalities in the upper category of altitude, and significantly lower in the intermediate altitude category compared to the lowlands. Our findings provide evidence that municipalities with high altitude had similar mortality rate, and lower case-fatality rate and excess of mortality for COVID-19 compared to lowlands in Colombia.https://orcid.org/0000-0002-0100-1940Revista Internacional - IndexadaA2N
Trabajos sobre Paleolítico antiguo en el Valle Medio del Guadalquivir (Prov. de Córdoba)
Analizamos en este trabajo la situación en que se encuentran las tareas de nvestigación del Paleolítico Antiguo en el valle medio del Guadalquivir a su paso por la provincia de Córdoba, concretamente, y sobre todo, en los términos de Palma del Río, Hornachuelos y Posadas. Las prospecciones han revelado, por el momento, la existencia de una cantidad importante de yacimientos en superficie, algunos con muy buenas colecciones líticas, apareciendo en la presente campaña los primeros materiales en conexión estratigráfica
Role of the Fractalkine Receptor in CNS Autoimmune Inflammation: New Approach Utilizing a Mouse Model Expressing the Human CX3CR1
Multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS) is the leading cause of non-traumatic neurological disability in young adults. Immune mediated destruction of myelin and oligodendrocytes is considered the primary pathology of MS, but progressive axonal loss is the major cause of neurological disability. In an effort to understand microglia function during CNS inflammation, our laboratory focuses on the fractalkine/CX3CR1 signaling as a regulator of microglia neurotoxicity in various models of neurodegeneration. Fractalkine (FKN) is a transmembrane chemokine expressed in the CNS by neurons and signals through its unique receptor CX3CR1 present in microglia. During experimental autoimmune encephalomyelitis (EAE), CX3CR1 deficiency confers exacerbated disease defined by severe inflammation and neuronal loss. The CX3CR1 human polymorphism I249/M280 present in ∼20% of the population exhibits reduced adhesion for FKN conferring defective signaling whose role in microglia function and influence on neurons during MS remains unsolved. The aim of this study is to assess the effect of weaker signaling through hCX3CR1I249/M280 during EAE. We hypothesize that dysregulated microglial responses due to impaired CX3CR1 signaling enhance neuronal/axonal damage. We generated an animal model replacing the mouse CX3CR1 locus for the hCX3CR1I249/M280 variant. Upon EAE induction, these mice exhibited exacerbated EAE correlating with severe inflammation and neuronal loss. We also observed that mice with aberrant CX3CR1 signaling are unable to produce FKN and ciliary neurotrophic factor during EAE in contrast to wild type mice. Our results provide validation of defective function of the hCX3CR1I249/M280 variant and the foundation to broaden the understanding of microglia dysfunction during neuroinflammation. © 2018 Cardona et al
Materiales calcolíticos procedentes de "La Longuera" (El Viso, Córdoba)
El norte de la provincia de Córdoba conforma un marco de enorme interés para el análisis de los primeros momentos de la metalurgia en Andalucía Occidental dada la excepcional riqueza en recursos mineros, y muy especialmente cupríferos que encierra su subsuelo. A este hecho viene a sumarse su singularidad geográfica como lugar de interrelación entre los desarrollos culturales coetáneos en el valle del Guadalquivir, Extremadura y zona occidental de la Submeseta sur. Conscientes de estos hechos, nos planteamos hace varios años un programa de investigación que, partiendo de una serie de prospecciones sistemáticas, nos permitiera una primera y sólida aproximación a la dinámica del Calcolítico en estas tierras cordobesas, labor que ya ha dado sus primeros frutos (MURILLO, 1986,1986 b, 1987) y en la que debe inscribirse el presente trabajo
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