562 research outputs found
High-order harmonic generation driven by chirped laser pulses induced by linear and non linear phenomena
We present a theoretical study of high-order harmonic generation (HHG) driven
by ultrashort optical pulses with different kind of chirps. The goal of the
present work is perform a detailed study to clarify the relevant parameters in
the chirped pulses to achieve a noticeable cut-off extensions in HHG. These
chirped pulses are generated using both linear and nonlinear dispersive
media.The description of the origin of the physical mechanisms responsible of
this extension is, however, not usually reported with enough detail in the
literature. The study of the behaviour of the harmonic cut-off with these kind
of pulses is carried out in the classical context, by the integration of the
Newton-Lorentz equation complemented with the quantum approach, based on the
integration of the time dependent Schr\"odinger equation in full dimensions
(TDSE-3D), we are able to understand the underlying physics.Comment: 13 pages, 8 figure
Infrared Observations of AGN
We present results from an imaging and spectroscopic study of the dust
properties of Seyfert galaxies in the 1-10um range. The data are compared to
state of the art models of torus emission to constrain geometrical and physical
properties of the obscuring medium.Comment: 2 pages, to appear in the IAU Symp.No.222 proceedings:"The Interplay
among Black Holes, Stars and ISM in Galactic Nuclei", Gramado, Brazil, March
1-5, 200
Distribución y relaciones sistemáticas entre poblaciones del género Ctenomys (Rodentia, Ctenomydae) de la provincia de Mendoza (Argentina)
Generating Groups of Products Using Graph Mining Techniques
AbstractRetail industry has evolved. Nowadays, companies around the world need a better and deeper understanding of their customers. In order to enhance store layout, generate customers groups, offers and personalized recommendations, among others. To accomplish these objectives, it is very important to know which products are related to each other.Classical approaches for clustering products, such as K-means or SOFM, do not work when exist scattered and large amounts of data. Even association rules give results that are difficult to interpret. These facts motivate us to use a novel approach that generates communities of products. One of the main advantages of these communities is that are meaningful and easily interpretable by retail analysts. This approach allows the processing of billions of transaction records within a reasonable time, according to the needs of companies
Análisis estadístico de los resultados de una investigación de los efectos de la influencia de la contaminación atmosférica sobre indicadores biológicos en escolares de sexo masculino
Con el objeto de buscar indicadores biológicos humanos de los efectos de la contaminación atmosférica se ha ejecutado un proyecto analítico exploratorio con poblaciones escolares en el centro de la ciudad de Santiago y en la comuna rural de María Pinto (Región Metropolitana). Se trabajó con 114 voluntarios escolares varones entre 10 y 14 años en el Instituto Nacional en Santiago y con un grupo de conrtol, similar, de 51 escolares en María Pinto. En sangre venosa y saliva obtenidas de estos voluntarios se hicieron determinaciones de variables inmunológicas, hematológicas y bioquímicas y medición de la actividad fagocítica del macrófago de sangre periférica. Se hicieron igualmente determinaciones antropométricas. Se determinó también factores de contaminación atmosférica por partículas en ambos lugares: se comprobó que la calidad de aire es significativamente diferente en ellos. Se resumen los resultados globales del proyecto y su análisis estadístico: se discuten tres metodologías alternativas que permitirían tomar en cuenta diferencias de estado nutricional entre ambas poblaciones que pudieran afectar los niveles de respuesta en las variables principales. Las concentraciones de imnunoglobulinas y los factores de complementos C3 y C4 no se muestran como indicadores biológicos efectivos de la contaminación por partículas en la atmósfera. Subsiste la posibilidad de que las variables: capacidad antioxidante del plasma, metahemoglobina, hematocrito, concentración de Fe en materia seca de sangre y otras puedan servir como tales indicadores. Las variaciones conjuntas del índice de fagocitosis y del % de killing evidencian un significativo stress oxidativo
Optimal observational scheduling framework for binary and multiple stellar systems
The optimal instant of observation of astrophysical phenomena for objects
that vary on human time-sales is an important problem, as it bears on the
cost-effective use of usually scarce observational facilities. In this paper we
address this problem for the case of tight visual binary systems through a
Bayesian framework based on the maximum entropy sampling principle. Our
proposed information-driven methodology exploits the periodic structure of
binary systems to provide a computationally efficient estimation of the
probability distribution of the optimal observation time. We show the
optimality of the proposed sampling methodology in the Bayes sense and its
effectiveness through direct numerical experiments. We successfully apply our
scheme to the study of two visual-spectroscopic binaries, and one purely
astrometric triple hierarchical system. We note that our methodology can be
applied to any time-evolving phenomena, a particularly interesting application
in the era of dedicated surveys, where a definition of the cadence of
observations can have a crucial impact on achieving the science goals.Comment: Accepted for publication to PASP. 23 pages, 2 Tables, 9 Figures, 2
Appendice
Beta2-glycoprotein I inhibition of mouse Kupffer cells respiratory burst depends on liver architecture
Protective effects of eicosapentaenoic acid plus hydroxytyrosol supplementation against white adipose tissue abnormalities in mice fed a high-fat diet
Objective: Obesity induced by high-fat diet (HFD) elicits white adipose tissue dysfunction. In this study, we have hypothesized that the metabolic modulator eicosapentaenoic acid (EPA) combined with the antioxidant hydroxytyrosol (HT) attenuates HFD-induced white adipose tissue (WAT) alterations. Methods: C57BL/6J mice were administered with a HFD (60% fat, 20% protein, 20% carbohydrates) or control diet (CD; 10% fat, 20% protein, 70% carbohydrates), with or without EPA (50 mg/kg/day), HT (5 mg/kg/day), or both for 12 weeks. Determinations in WAT include morphological parameters, EPA and docosahexaenoic acid content in phospholipids (gas chromatography), lipogenesis, oxidative stress (OS) and inflammation markers, and gene expression and activities of transcription factors, such as sterol regulatory element-binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor-gamma (PPAR-γ), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) (p65 subunit) and nuclear factor erythroid 2-related factor 2 (Nrf2) (quantitative polymerase chain reaction and enzyme linked immunosorbent assay). Results: HFD led to WAT hypertrophy in relation to PPAR-γ downregulation. WAT metabolic dysfunction was characterized by upregulation of lipogenic SREBP-1c system, mitochondrial energy metabolism depression, loss of the antioxidant Nrf2 signaling with OS enhancement, n-3 long-chain polyunsaturated fatty acids depletion and activation of the pro-inflammatory NF-κB system. EPA and HT co-supplementation diminished HFD-dependent effects additively, reaching values close or similar to controls. Conclusion: Data presented strengthen the importance of combined protocols such as EPA plus HT to attenuate metabolic-inflammatory states triggered by obesity
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