73 research outputs found
Un modelo de virtudes relacionales y principios guÃa para una comunidad-empresa basada en el diálogo
El presente artÃculo busca argumentar cómo las virtudes relacionales favorecen el diálogo en una organización. El concepto de virtud se analiza a partir de su perspectiva aristotélica, profundizando en la vertiente personal y relacional de las virtudes. Se entiende que la virtud se encuentra estrechamente vinculada a la idea de comunidad en la vida empresarial y el diálogo es el espacio en donde convergen las virtudes relacionales con los principios empresariales. A partir de las anteriores afirmaciones se plantean estas preguntas de investigación: ¿cuáles son las virtudes que deben dar forma al ethos de la empresa bajo las cuáles encuentra sustento el diálogo? ¿Qué virtudes pueden ser catalizadoras de los principios guÃa de una ética empresarial sustentada en el diálogo? Se propone
un modelo que intenta articular principios guÃa y virtudes relacionales para favorecer la ética del diálogo en las empresas
Lowering the background level and the energy threshold of Micromegas x-ray detectors for axion searches
Axion helioscopes search for solar axions by their conversion in x-rays in
the presence of high magnetic fields. The use of low background x-ray detectors
is an essential component contributing to the sensitivity of these searches. In
this work, we review the recent advances on Micromegas detectors used in the
CERN Axion Solar Telescope (CAST) and proposed for the future International
Axion Observatory (IAXO). The actual setup in CAST has achieved background
levels below 10 keV cm s, a factor 100 lower than
the first generation of Micromegas detectors. This reduction is based on active
and passive shielding techniques, the selection of radiopure materials, offline
discrimination techniques and the high granularity of the readout. We describe
in detail the background model of the detector, based on its operation at CAST
site and at the Canfranc Underground Laboratory (LSC), as well as on Geant4
simulations. The best levels currently achieved at LSC are low than 10
keV cm s and show good prospects for the application of
this technology in IAXO. Finally, we present some ideas and results for
reducing the energy threshold of these detectors below 1 keV, using
high-transparent windows, autotrigger electronics and studying the cluster
shape at different energies. As a high flux of axion-like-particles is expected
in this energy range, a sub-keV threshold detector could enlarge the physics
case of axion helioscopes.Comment: Proceedings of 3rd International Conference on Technology and
Instrumentation in Particle Physics (TIPP 2014
The potential of discrimination methods in a high pressure xenon TPC for the search of the neutrinoless double-beta decay of Xe-136
In the search for the neutrinoless double beta decay of 136Xe, a high pressure xenon time projection chamber (HPXe-TPC) has two advantages over liquid xenon TPCs: a better energy resolution and the access to topological features, which may provide extra discrimination from background events. The PandaX-III experiment has recently proposed a 200 kg HPXe-TPC based on Micromegas readout planes, to be located at the Jinping Underground Laboratory in China. Its detection concept is based on two results obtained within the T-REX project: Micromegas readouts can be built with extremely low levels of radioactivity; and the operation in xenon-trimethylamine at 10 bar in realistic experimental conditions has proven an energy resolution of 3% FWHM at the region of interest. In this work, two discrimination methods are applied to simulated signal and background data in a generic 200 kg HPXe-TPC, based on two well-known algorithms of graph theory: the identification of connections and the search for the longest path. Rejection factors greater than 100 are obtained for small pixel sizes and a signal efficiency of 40%. Moreover, a new observable (the blob charge density) rejects better surface contaminations, which makes the use of a trigger signal (T0) not imperative in this experiment
Real-Time Onboard Global Nonlinear Aerodynamic Modeling from Flight Data
Flight test and modeling techniques were developed to accurately identify global nonlinear aerodynamic models onboard an aircraft. The techniques were developed and demonstrated during piloted flight testing of an Aermacchi MB-326M Impala jet aircraft. Advanced piloting techniques and nonlinear modeling techniques based on fuzzy logic and multivariate orthogonal function methods were implemented with efficient onboard calculations and flight operations to achieve real-time maneuver monitoring and analysis, and near-real-time global nonlinear aerodynamic modeling and prediction validation testing in flight. Results demonstrated that global nonlinear aerodynamic models for a large portion of the flight envelope were identified rapidly and accurately using piloted flight test maneuvers during a single flight, with the final identified and validated models available before the aircraft landed
Low Background Micromegas in CAST
Solar axions could be converted into x-rays inside the strong magnetic field
of an axion helioscope, triggering the detection of this elusive particle. Low
background x-ray detectors are an essential component for the sensitivity of
these searches. We report on the latest developments of the Micromegas
detectors for the CERN Axion Solar Telescope (CAST), including technological
pathfinder activities for the future International Axion Observatory (IAXO).
The use of low background techniques and the application of discrimination
algorithms based on the high granularity of the readout have led to background
levels below 10 counts/keV/cm/s, more than a factor 100 lower than
the first generation of Micromegas detectors. The best levels achieved at the
Canfranc Underground Laboratory (LSC) are as low as 10
counts/keV/cm/s, showing good prospects for the application of this
technology in IAXO. The current background model, based on underground and
surface measurements, is presented, as well as the strategies to further reduce
the background level. Finally, we will describe the R&D paths to achieve
sub-keV energy thresholds, which could broaden the physics case of axion
helioscopes.Comment: 6 pages, 3 figures, Large TPC Conference 2014, Pari
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The Colorado Plateau Coring Project (CPCP): 100 Million Years of Earth System History
Lasting over 100 million years, the early Mesozoic (252 to 145 Ma) is punctuated by two of the five major mass extinctions of the Phanerozoic (Permo-Triassic and Triassic-Jurassic) plus several smaller extinction events. It witnessed the evolutionary appearance of the modem terrestrial biota including frogs, salamanders, turtles, lizards, crocodilians, dinosaurs, birds, and mammals, and spans a time of dramatic climate changes on the continents. What is arguably the richest record of these events lies in the vast (- 2.5 million km2) complex of epicontinental basins in the western part of Pangea, now largely preserved on the Colorado Plateau (Fig.l). Since the mid-19th century, classic studies of these basins, their strata, and their fossils have made this succession instrumental in framing our context of the early Mesozoic Earth system as reflected in the international literature. Despite this long and distinguished history of study of the Colorado Plateau region, striking ambiguities in temporal resolution, major uncertainties in global correlations, and significant doubts about paleolatitudinal position hamper incorporation of the huge amount of information from the region into-tests of major competing climatic, biotic, and tectonic hypotheses and a fundamental understanding of Earth system processes
Micromegas for dark matter searches: CAST/IAXO & TREX-DM experiments
The most compelling candidates for Dark Matter to day are WIMPs and axions. The applicability of gasesous Time Projection Chambers (TPCs) with Micromesh Gas Structures (Micromegas) to the search of these particles is explored within this work. Both particles would produce an extremely low rate at very low energies in particle detectors. Micromegas detectors can provide both low background rates and low energy threshold, due to the high granularity, radiopurity and uniformity of the readout. Small (few cm wide) Micromegas detectors are used to image the ax ion-induced x-ray signal expected in the CERN Axion Solar Telescope (CAST) experiment. We show the background levels obtained in CAST and the prospects to further reduce them to the values required by the Internation Axion Observatory (IAXO). We also present TREX-DM. a scaled-up version of the Micromegas used in axion research, but this time dedicated to the low-mass WIMP detection. TREX-DM is a high-pressure Micromegas-based TPC designed to host a few hundreds of grams of light nuclei (argon or neon) with energy thresholds potentially at the level of 100 eV. The detector is described in detail, as well as the results of the commissioning and characterization phase on surface. Besides, the background model of TREX-DM is presented, along with the anticipated sensitivity of this search, which could go beyond current experimental limits
Performance of micromegas detectors in the CAST Experiment
CERN Axion Solar Telescope (CAST) experiment is searching for axions coming from the Sun. Inside transverse magnetic fields, axions can be converted into X-rays, which can be detected by X-ray detectors. The expected energy of the signal in CAST is in the 1-10 keV range. Low noise and low background detectors are necessary to increase the sensitivity of the experiment. Micro Mesh Gaseous Structure (micromegas) detectors have been used in CAST since the beginning, providing good energy and spatial resolution for CAST's needs. CAST has been intensely studying micromegas detectors to develop new technologies. Initially, CAST detectors consisted of a micromegas, a Time Projection Chamber (TPC) and a Charged Couple Device (CCD), however the improvements in micromegas technologies encouraged CAST to replace the TPC with 2 new micromegas detectors. In some periods during CAST run, ultra low background has been observed in one of the micromegas detectors and it is being investigated through simulations and laboratory tests carried out at Canfranc Underground Laboratory. If this low background is indeed not a systematic effect, it can open new possibilities on rare event searches
Cosmogenic production of tritium in dark matter detectors
The direct detection of dark matter particles requires ultra-low background conditions at energies below a few tens of keV. Radioactive isotopes are produced via cosmogenic activation in detectors and other materials and those isotopes constitute a background source which has to be under control. In particular, tritium is specially relevant due to its decay properties (very low endpoint energy and long half-life) when induced in the detector medium, and because it can be generated in any material as a spallation product. Quantification of cosmogenic production of tritium is not straightforward, neither experimentally nor by calculations. In this work, a method for the calculation of production rates at sea level has been developed and applied to some of the materials typically used as targets in dark matter detectors (germanium, sodium iodide, argon and neon); it is based on a selected description of tritium production cross sections over the entire energy range of cosmic nucleons. Results have been compared to available data in the literature, either based on other calculations or from measurements. The obtained tritium production rates, ranging from a few tens to a few hundreds of nuclei per kg and per day at sea level, point to a significant contribution to the background in dark matter experiments, requiring the application of specific protocols for target material purification, material storing underground and limiting the time the detector is on surface during the building process in order to minimize the exposure to the most dangerous cosmic ray components
Complicaciones de la colocación de malla sintética vaginal para la incontinencia urinaria de esfuerzo
ResumenAntecedentesLas mallas para la incontinencia urinaria (IU) se han utilizado a pesar de la falta de evidencia de nivel i en la literatura para evaluar su seguridad y eficacia a largo plazo. Las complicaciones relacionadas con la malla provocaron una advertencia emitida por la FDA en 2008 y dejaron de ser consideradas eventos raros. Las complicaciones más comunes son la retención aguda de orina, sangrado, recurrencia o persistencia de la IU, erosión de uretra e infección de la malla.ObjetivoConocer cuáles son las complicaciones derivadas del tratamiento quirúrgico de la IU femenina con la colocación de mallas suburetrales.Material y métodoSe analizaron los pacientes con diagnóstico de IU operadas con cirugÃa antiincontinencia y colocación de malla vaginal del año 2007 al 2014. Se analizó las complicaciones derivadas de la colocación de malla y la recuperación de continencia.ResultadosA 58 pacientes se les colocó sling (cabestrillo) con malla sintética; edad promedio de 56 años. El 51% de las pacientes tenÃan IU de esfuerzo y el 49% IU mixta. Las complicaciones tempranas fueron: 4 pacientes con retención aguda de orina. Las complicaciones tardÃas: dolor uretral o vaginal (12.2%), dispareunia (20%) y extrusión de malla (10%) manejado con retiro de la misma, 2 de ellas requiriendo 2 procedimientos quirúrgicos. El 12% presentaron urgencia de novo, el 90.2% evolucionaron sin incontinencia, el 9.7% con IU postoperatoria y 2 pacientes sin mejorÃa.DiscusiónNuestra serie, aunque pequeña, muestra una baja tasa de complicaciones a largo plazo relacionadas con la malla en comparación con la mayorÃa de las series que muestran una tasa de reoperación de hasta>70% y con múltiples casos de retiro de malla, por lo que en nuestra experiencia los slings suburetrales continúan siendo una opción adecuada en el manejo de la IU.ConclusionesLos slings suburetrales son una opción segura y efectiva en el manejo de la IU.AbstractBackgroundSurgical mesh has been used for treating urinary incontinence (UI) despite the lack of level i evidence in the literature evaluating its long-term safety and efficacy. Mesh-related complications were responsible for a warning issued by the FDA in 2008 and they stopped being considered rare events. The most common complications are acute urinary retention, bleeding, recurrence or persistence of UI, erosion of the urethra, and mesh infection.AimsTo determine the complications derived from surgical UI treatment with the placement of suburethral mesh in women.Material and methodPatients diagnosed with UI that underwent anti-incontinence surgery with the placement of vaginal mesh within the time frame of 2007 and 2014 were analyzed. Mesh placement complications and the recovery of continence were evaluated.ResultsA synthetic mesh sling was placed in 58 patients with a mean age of 56 years. A total of 51% of the patients had stress urinary incontinence and 49% had mixed urinary incontinence. Early complications were: 4 patients with acute urine retention. Late complications were: urethral or vaginal pain (12.2%), dyspareunia (20%), and mesh extrusion (10%) that was managed through mesh removal; 2 of those patients required surgical procedures. Twelve percent of the patients presented with de novo urgency, 90.2% progressed with no incontinence, 9.7% presented with postoperative UI, and 2 patients had no improvement.DiscussionAlthough small, our case series showed a low long-term complication rate with the use of surgical mesh, compared with the majority of case series that demonstrate a re-operation rate>70%, as well as numerous cases of mesh removal. Thus, it is our experience that suburethral slings continue to be an adequate UI management option.ConclusionsSuburethral slings are a safe and effective option in UI management
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