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Search Results: 1 - 10 of 583562 matches for " ANDRéS J. HERNáNDEZ "
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NewsPad: Designing for Collaborative Storytelling in Neighborhoods
J. Nathan Matias,Andrés Monroy-Hernández
Computer Science , 2015, DOI: 10.1145/2559206.2581354
Abstract: This paper introduces design explorations in neighborhood collaborative storytelling. We focus on blogs and citizen journalism, which have been celebrated as a means to meet the reporting needs of small local communities. These bloggers have limited capacity and social media feeds seldom have the context or readability of news stories. We present NewsPad, a content editor that helps communities create structured stories, collaborate in real time, recruit contributors, and syndicate the editing process. We evaluate NewsPad in four pilot deployments and find that the design elicits collaborative story creation.
FOTOGRAFIAMOS EL COLOR TAL Y COMO LO PERCIBIMOS?
J. L. Nieves,J. A. García,J. Hernández-Andrés,R. Huertas
Revista Eureka sobre Ense?anza y Divulgación de las Ciencias , 2010,
Abstract: FOTOGRAFIAMOS EL COLOR TAL Y COMO LO PERCIBIMOS?
Análisis de trazos de las especies mexicanas de Rhus subgénero Lobadium (ANGIOSPERMAE: ANACARDIACEAE)
Andrés Hernández,Agustina Rosa; Morrone,Juan J; Terrazas,Teresa; López Mata,Lauro;
Interciencia , 2006,
Abstract: the subgenus lobadium of the genus rhus contains about 25 species, distributed mainly in mexico. the geographic distribution of these species was analyzed through a panbiogeographic approach, based on a parsimony analysis of endemicity. distribution of subgenus lobadium lies principally in the mexican transition zone, constituting a nearctic element. three generalized tracks were identified: 1) california-baja california; 2) mexican pacific coast-sierra madre occidental; and 3) tamaulipas-sierra madre del sur-transmexican vocanic belt- mexican plateau-sierra madre oriental. the first one coincides with the californian dominion, whereas the two others confirm the hipothesis of the mexican transition zone, in the mountain areas of mexico, where nearctic and neotropcial biotic elements overlap.
Technical Note: Characterisation of a DUALER instrument for the airborne measurement of peroxy radicals during AMMA 2006
D. Kartal, M. D. Andrés-Hernández, L. Reichert, H. Schlager,J. P. Burrows
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2010,
Abstract: A DUALER (dual-channel airborne peroxy radical chemical amplifier) instrument has been developed and optimised for the airborne measurement of the total sum of peroxy radicals during the AMMA (African Monsoon Multidisciplinary Analyses) measurement campaign which took place in Burkina Faso in August 2006. The innovative feature of the instrument is that both reactors are sampling simultaneously from a common pre-reactor nozzle while the whole system is kept at a constant pressure to ensure more signal stability and accuracy. Laboratory experiments were conducted to characterise the stability of the NO2 detector signal and the chain length with the pressure. The results show that airborne measurements using chemical amplification require constant pressure at the luminol detector. Wall losses of main peroxy radicals HO2 and CH3O2 were investigated. The chain length was experimentally determined for different ambient mixtures and compared with simulations performed by a chemical box model. The DUALER instrument was successfully mounted within the German DLR-Falcon. The analysis of AMMA data utilises a validation procedure based on the O3 mixing ratios simultaneously measured onboard. The validation and analysis procedure is illustrated by means of the data measured during the AMMA campaign. The detection limit and the accuracy of the ambient measurements are also discussed.
Peroxy radical observations over West Africa during the AMMA 2006 campaign: Photochemical activity in episodes of formation of convective systems on the basis of radical measurements
M. D. Andrés-Hernández,D. Kartal,L. Reichert,J. P. Burrows
Atmospheric Chemistry and Physics Discussions , 2009,
Abstract: Peroxy radical measurements made on board the DLR-Falcon research aircraft over West Africa within the African Monsoon Multidisciplinary Analysis (AMMA) campaign during the 2006 wet monsoon are presented in this study. The analysis of data focuses on the photochemical activity of air masses sampled during episodes of intense convection and biomass burning. Generally, the total sum of peroxy radical mixing ratios, measured in the outflow of convective clouds, are quite variable but occasionally are coupled with the NO variations indicating the coexistence, or simultaneously emission of NOx, with a potential radical precursor (i.e., formaldehyde, acetone or peroxides) which has likely been transported to higher atmospheric layers. Based on the measurements, significant O3 production rates up to 2 ppb/h in the MCS outflow are estimated by using a box model with simplified chemistry. Peroxy radicals having mixing ratios around 20–25 pptv and with peak values of up to 60–70 pptv are measured within biomass burning plumes, detected at the coast in Ghana. Calculations of back-trajectory densities confirm the origin of these air masses being a biomass burning region at southern latitudes and close to the Gulf of Guinea, according to satellite pictures. Measured peroxy radical concentrations agree reasonably with modelled estimations taking into account simple local chemistry. Moreover the vertical profiles taken at the aircraft base in Ouagadougou, Burkina Faso, indicate the common feature of having maximum concentrations between 2 and 4 km, in agreement with other literature values obtained under similar conditions.
Corrigendum to ''Peroxy radical observations over West Africa during AMMA 2006: photochemical activity in the outflow of convective systems
M. D. Andrés-Hernández,D. Kartal,L. Reichert,J. P. Burrows
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2009,
Abstract: No abstract available.
REDUCCIóN DE DIMENSIONES PARA CLASIFICACIóN DE DATOS MULTIDIMENSIONALES USANDO MEDIDAS DE INFORMACIóN
ANDRéS J. HERNáNDEZ,EDILSON DELGADO TREJOS,JORGE RIVERA PIEDRAHITA,GERMáN CASTELLANOS
Scientia Et Technica , 2006,
Abstract: El enorme desarrollo tecnológico ha creado un concepto de información con áreas extensas de aplicación para tareas referentes al entrenamiento de sistemas automáticos. Este trabajo propone una metodología basada en el análisis de componentes independientes (ICA), que incluye el uso de medidas de información, para realizar reducción de dimensiones en conjuntos de datos multidimensionales. La metodología usa un principio de relevancia, con el fin de hallar la representación reducida mientras se conserva la estructura relacionada a la información inicial. La metodología se compara y se conjuga con un sistema básico de selección de características cuya función de evaluación usa la medida de entropía logrando mejores resultados en la clasificación.
Localización de Fallas Monofásicas en Sistemas de Distribución Considerando el Efecto Capacitivo y la No Homogeneidad de las Líneas
Andrés F. Panesso-Hernández,Juan J. Mora-Flórez
Scientia Et Technica , 2012,
Abstract: En el presente artículo se propone una alternativa para la localización de fallas monofásicas paralelas de baja impedancia en sistemas eléctricos de distribución radiales a partir de las mediciones de los fundamentales de tensión y corriente por fase obtenidos en la cabecera del circuito. Esta propuesta se fundamenta en el hecho de que los sistemas dedistribución típicos son de carácter desbalanceado, sus tramos no son homogéneos y mucho menos transpuestos, además el efecto capacitivo puede afectar considerablemente el comportamiento de un método de localización de falla sobre todo si éste contiene tramos subterráneos o si el sistema está ligeramente cargado en el momento de la falla.
Towards Uncertainty Quantification and Inference in the stochastic SIR Epidemic Model
Marcos A. Capistrán,J. Andrés Christen,Jorge X. Velasco-Hernández
Statistics , 2011,
Abstract: In this paper we introduce a novel method to conduct inference with models defined through a continuous-time Markov process, and we apply these results to a classical stochastic SIR model as a case study. Using the inverse-size expansion of van Kampen we obtain approximations for first and second moments for the state variables. These approximate moments are in turn matched to the moments of an inputed generic discrete distribution aimed at generating an approximate likelihood that is valid both for low count or high count data. We conduct a full Bayesian inference to estimate epidemic parameters using informative priors. Excellent estimations and predictions are obtained both in a synthetic data scenario and in two Dengue fever case studies.
Chemical abundances of the secondary star in the Neutron star X-ray binary Cygnus X-2
L. Suárez-Andrés,J. I. González Hernández,G. Israelian,J. Casares,R. Rebolo
Physics , 2014, DOI: 10.1093/mnras/stu2612
Abstract: We present UES@WHT high-resolution spectra of the low-mass X-ray binary (LMXB) Cygnus X-2. We have derived the stellar parameters of the secondary star using $\chi^{2}$ minimisation procedure, and taking into account any possible veiling from the accretion disk. We determine a metallicity higher than solar ([Fe/H]$=0.27\pm0.19$), as seen also in the neutron star X-ray binary Centaurus X-4. The high-quality of the secondary's spectrum allow us to determine the chemical abundances of O, Mg, Si, Ca, S, Ti, Fe and Ni. We found that some $\alpha$-elements (Mg, Si, S, Ti) are enhanced, consistent with a scenario of contamination of the secondary star during the supernova event. Surprisingly oxygen appears to be under-abundant, whereas enhanced abundances of Fe and Ni are measured. Assuming that these abundances come from matter that has been processed in the SN and then captured by the secondary star, we explore different SN explosion scenarios with diverse geometries. A non-spherically symmetric SN explosion, with a low mass cut, seems to reproduce better the observed abundance pattern of the secondary star compared to the spherical case.
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