1,175 research outputs found
Identification of low energy neutral and charged cosmic ray events in large wide field observatorie
The lower energy thresholds of large wide-field gamma-ray observatories are
often determined by their capability to deal with the very low-energy cosmic
ray background. In fact, in observatories with areas of tens or hundreds of
thousands of square meters, the number of background events generated by the
superposition of random, very low energy cosmic rays is huge and may exceed by
far the possible signal events. In this article, we argue that a trigger
strategy based on pattern recognition of the shower front can significantly
reject the background, keeping a good efficiency and a good angular accuracy
(few square degrees) for gamma rays with energies as low as tens of GeV. In
this way, alerts can be followed or emitted within time lapses of the order of
the second, enabling wide-field gamma-ray observatories to better contribute to
global multi-messenger networks of astrophysical observatories.Comment: 9 pages, 14 figure
Molecular alterations of KIT and PDGFRA in GISTs: evaluation of a Portuguese series
To assess KIT and PDGFRA mutations frequencies in a Portuguese series of gastrointestinal stromal tumours (GISTs)
Estudio de las propiedades de adsorción/desorción de gas en el carbón de la Cuenca de Sabinas en México: Study of gas adsorption/desorption properties in coals of Sabinas Basin on Mexico
http://sherpa.ac.uk/romeo/issn/2007-9753/El objetivo principal de esta investigación, se enfoca en el estudio de las propiedades de adsorción/desorción de CH4 en los yacimientos de gas asociado al carbón, los cuales se ubican en la porción noreste de México, con el fin de comprender su comportamiento desde el punto de vista de los yacimientos no convencionales.
Para continuar con el desarrollo de este proyecto, se llevó a cabo una campaña de muestreo a cargo del Servicio Geológico Mexicano (SGM), el cual nos proporcionó 7 muestras de carbón bituminoso, procedentes de la Cuenca de Sabinas para su caracterización. La caracterización general incluyó: (1) Análisis inmediatos o primarios de humedad y ceniza, (2) Análisis elemental para la determinación de (C, H, O, N, y S), (3) Análisis petrográfico para determinar el tipo de materia orgánica, (4) Pirolisis Rock-Eval®6 para conocer su potencial petrolífero. El conjunto de estos análisis nos permitieron evaluar las muestras para desarrollar mediante “Isotermas de Langmuir” los ensayos de adsorción/desorción de CH4 y la interpretación de los parámetros que influyen en el proceso de adsorción.
Para el desarrollo de las pruebas de adsorción/desorción se utilizó la técnica termo-volumétrica, observando capacidades de almacenamiento de gas metano de 202.11 scf/ton (7.07m3/ton) a 364.76 scf/ton (10.47m3/ton). Estos resultados nos permitieron interpretar las características físicas y químicas que influyen en la capacidad de almacenamiento del gas en el carbón. Anticipando como conclusión general que: la adsorción del gas aumenta con el rango/madurez. También se estudió la influencia de la composición maceral en el proceso de sorción y se verificó que la capacidad de almacenamiento de gas está íntimamente relacionada al contenido de vitrinita. Esto nos condujo a retomar las declaraciones de algunos autores (Chalmers y Bustin, 2008; Zhang et al, 2012) quienes verificaron que la capacidad de adsorción en base al COT aumenta en el siguiente orden: tipo I < tipo II < tipo III. Esto se atribuyó a que la vitrinita tiene una mayor capacidad de adsorción, en comparación con otros tipos de macerales.The main objective of this research was to study the gas adsorption/desorption properties in Coal Bed Methane reservoirs located in the North-eastern Mexico, and to understand the behavior of unconventional reservoirs.
The Servicio Geológico Mexicano (SGM) performed a sampling campaign. For the characterization, the SGM providing us 7 bituminous coal samples from the Sabinas Basin. The general characterization included: (1) immediate or primary moisture and ash analysis (2) elemental analysis for (C, H, O, N, and S) quantification, (3) petrographic analysis for organic matter type determination, (4) Rock-Eval®6 Pyrolysis, for oil potential generation determination. After results evaluation, 7 samples were selected, in order to develop adsorption/desorption CH4 tests by “Langmuir Isotherms” and to understand of parameters affecting the adsorption process.
Using thermo-volumetric technique could be observed storage capacities of methane gas between 202.11 scf/ton (7.07m3/ton) and 364.76 scf/ton (10.47 m3/ton). The adsorption/desorption tests results, let us to identify the physical and chemical characteristics of the samples influencing
the gas storage capacity in the coal. A general conclusion is given; the gas adsorption increases with the rank/maturity. Also, the influence of the maceral composition in the process of sorption is recognized, and the capacity of gas storage is closely related to the vitrinite content.
According to Chalmers y Bustin (2008), and Zhang et al. (2012), the capacity of adsorption as TOC, increases in the next order: type I < type II < type III. This is attributed to high adsorption capacity of vitrinite, compared with other macerals types.info:eu-repo/semantics/publishedVersio
Detection of the Cherenkov light diffused by Sea Water with the ULTRA Experiment
The study of Ultra High Energy Cosmic Rays represents one of the most
challenging topic in the Cosmic Rays and in the Astroparticle Physics fields.
The interaction of primary particles with atmospheric nuclei produces a huge
Extensive Air Shower together with isotropic emission of UV fluorescence light
and highly directional Cherenkov photons, that are reflected/diffused
isotropically by the impact on the Earth's surface or on high optical depth
clouds. For space-based observations, detecting the reflected Cherenkov signal
in a delayed coincidence with the fluorescence light improves the accuracy of
the shower reconstruction in space and in particular the measurement of the
shower maximum, giving a strong signature for discriminating hadrons and
neutrinos, and helping to estimate the primary chemical composition. Since the
Earth's surface is mostly covered by water, the ULTRA (UV Light Transmission
and Reflection in the Atmosphere)experiment has been designed to provide the
diffusing properties of sea water, overcoming the lack of information in this
specific field. A small EAS array, made up of 5 particle detectors, and an UV
optical device, have been coupled to detect in coincidence both electromagnetic
and UV components. The detector was in operation from May to December, 2005, in
a small private harbor in Capo Granitola (Italy); the results of these
measurements in terms of diffusion coefficient and threshold energy are
presented here.Comment: 4 pages, 3 figures, PDF format, Proceedings of 30th ICRC,
International Cosmic Ray Conference 2007, Merida, Yucatan, Mexico, 3-11 July
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Body composition and body fat distribution are related to cardiac autonomic control in non-alcoholic fatty liver disease patients
BACKGROUND/OBJECTIVES: Heart rate recovery (HRR), a cardiac autonomic control marker, was shown to be related to body composition (BC), yet this was not tested in non-alcoholic fatty liver disease (NAFLD) patients. The aim of this study was to determine if, and to what extent, markers of BC and body fat (BF) distribution are related to cardiac autonomic control in NAFLD patients. SUBJECTS/METHODS: BC was assessed with dual-energy X-ray absorptiometry in 28 NAFLD patients (19 men, 51±13 years, and 9 women, 47±13 years). BF depots ratios were calculated to assess BF distribution. Subjects’ HRR was recorded 1 (HRR1) and 2 min (HRR2) immediately after a maximum graded exercise test.
RESULTS: BC and BF distribution were related to HRR; particularly weight, trunk BF and trunk BF-to-appendicular BF ratio showed a negative relation with HRR1 (r 1⁄4 0.613, r 1⁄4 0.597 and r 1⁄4 0.547, respectively, Po0.01) and HRR2 (r 1⁄4 0.484, r 1⁄4 0.446, Po0.05, and r 1⁄4 0.590, Po0.01, respectively). Age seems to be related to both HRR1 and HRR2 except when controlled for BF distribution. The preferred model in multiple regression should include trunk BF-to-appendicular BF ratio and BF to predict HRR1 (r2 1⁄4 0.549; Po0.05), and trunk BF-to-appendicular BF ratio alone to predict HRR2 (r2 1⁄4 0.430; Po0.001).
CONCLUSIONS: BC and BF distribution were related to HRR in NAFLD patients. Trunk BF-to-appendicular BF ratio was the best independent predictor of HRR and therefore may be best related to cardiovascular increased risk, and possibly act as a mediator in age-related cardiac autonomic control variation.info:eu-repo/semantics/publishedVersio
The AMS-RICH velocity and charge reconstruction
The AMS detector, to be installed on the International Space Station,
includes a Ring Imaging Cerenkov detector with two different radiators, silica
aerogel (n=1.05) and sodium fluoride (n=1.334). This detector is designed to
provide very precise measurements of velocity and electric charge in a wide
range of cosmic nuclei energies and atomic numbers. The detector geometry, in
particular the presence of a reflector for acceptance purposes, leads to
complex Cerenkov patterns detected in a pixelized photomultiplier matrix. The
results of different reconstruction methods applied to test beam data as well
as to simulated samples are presented. To ensure nominal performances
throughout the flight, several detector parameters have to be carefully
monitored. The algorithms developed to fulfill these requirements are
presented. The velocity and charge measurements provided by the RICH detector
endow the AMS spectrometer with precise particle identification capabilities in
a wide energy range. The expected performances on light isotope separation are
discussed.Comment: Contribution to the ICRC07, Merida, Mexico (2007); Presenter: F.
Bara
The RICH detector of the AMS-02 experiment: status and physics prospects
The Alpha Magnetic Spectrometer (AMS), whose final version AMS-02 is to be
installed on the International Space Station (ISS) for at least 3 years, is a
detector designed to measure charged cosmic ray spectra with energies up to the
TeV region and with high energy photon detection capability up to a few hundred
GeV. It is equipped with several subsystems, one of which is a proximity
focusing RICH detector with a dual radiator (aerogel+NaF) that provides
reliable measurements for particle velocity and charge. The assembly and
testing of the AMS RICH is currently being finished and the full AMS detector
is expected to be ready by the end of 2008. The RICH detector of AMS-02 is
presented. Physics prospects are briefly discussed.Comment: 5 pages. Contribution to the 10th ICATPP Conference on Astroparticle,
Particle, Space Physics, Detectors and Medical Physics Applications (Como
2007). Presenter: Rui Pereir
Investigação epidemiológica e controle da Esquistossomose e demais parasitoses intestinais na Zona da Mata Mineira
-O presente trabalho avalia a cobertura e a qualidade do cadastro das famílias nos municípios mineiros de Coronel Pacheco, Goianá, e Piau, através
da comparação entre a ficha A aplicada pelo agente comunitário de saúde e os dados obtidos de investigações realizadas diretamente nos
domicílios. Foram entrevistadas, no período de novembro a dezembro de 2006, 192 famílias selecionadas de forma aleatória. A alta cobertura do
cadastro das famílias verificada (97,9%) assim como a fidedignidade para os campos “família corresponde ao endereço” e “família está completa”
(95,7% e 93,1%), observados nos três municípios, indicaram a confiabilidade do cadastro realizado pelo PSF. Os dados referentes à atualização das
gestantes, hipertensos, e crianças menores de um ano, não tiveram a mesma confiabilidade. Quanto ao perfil dos agentes comunitários de saúde,
que atuaram nos três municípios, a maioria dos entrevistados eram mulheres, com menos de 25 anos e estavam estudando ou já haviam completado
o segundo grau. O tempo médio de permanência dos profissionais no PSF foi de 10 meses, sendo que 45% dos agentes foram submetidos a
concurso municipal e os demais contratados. Os autores concluem que o cadastro do PSF (ficha A/SIAB) nos três municípios é confiável como base
populacional para o cálculo amostral, justificando sua utilização como ferramenta legítima para a realização de pesquisas de campo nas áreas
básicas e clínicas
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