3,949 research outputs found

    Constant of Motion for several one-dimensional systems and outlining the problem associated with getting their Hamiltonians

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    The constants of motion of the following systems are deduced: a relativistic particle with linear dissipation, a no-relativistic particle with a time explicitly depending force, a no-relativistic particle with a constant force and time depending mass, and a relativistic particle under a conservative force with position depending mass. The problem of getting the Hamiltonian for these systems is determined by getting the velocity as an explicit function of position and generalized linear momentum, and this problem can be solved a first approximation for the first above system.Comment: 15 pages, Te

    Influencia del tiempo de gelificación sobre las propiedades estructurales, vibracionales y eléctricas del compósito PEG0.2/V2O5

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    Se estudiaron las propiedades estructurales, vibracionales y eléctricas de películas V2O5·nH2O y PEG0.2/V2O5 en función del tiempo de gelificación. Las películas fueron sinterizadas por sol-gel mediante la ruta del pentóxido de vanadio sobre sustratos de vidrio previamente tratados. La caracterización se llevo a cabo mediante Difracción de Rayos-X, Espectroscopía Raman y el método de las cuatro puntas convencional de van der Pauw. Los resultados indican que el aumento en el tiempo de gelificación del sol precursor (V2O5.nH2O) incrementa la calidad cristalina, el grado de hidratación, y la concentración de iones V5+ en las películas. En el compósito híbrido (PEG0.2/V2O5) los iones VO2+ actúan como enlazantes entre las cadenas poliméricas haciéndolas más compactas, lo cual facilita la movilidad de los portadores de carga eléctrica entre los iones vanadios. Los resultados mostraron una transición de fase semiconductormetal alrededor de 34°C, una transición óptica del tipo indirecta (para V2O5·nH2O) y una transición vítrea alrededor de Tg=-69°C.Structural, vibrational and electrical properties of V2O5·nH2O and PEG0.2/V2O5 films as a function of gelation time were studied. The films were sintered by sol-gel using vanadium pentoxide route on glass substrates previously treated. Films were characterized by X-Ray Diffraction, Raman Spectroscopy and the four-point van der Pauw conventional method. The results indicated that when the gelation time of the precursor (V2O5·nH2O) is increased, the crystalline quality, the degree of hydration, and V5+ ion concentration are increased. In the hybrid composite (PEG0.2/V2O5), VO2+ ions act as bonding between the polymer chains, making them more compact to facilitate the mobility of electric charge carriers between vanadium ions. The results showed a semiconductor-metal transition about 34°C, an indirect optical transition (V2O5·nH2O) and a vitreous transition around Tg=-69°C.Fil: Londoño Calderon, Cesar Leandro. Universidad Nacional de Colombia; Colombia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Jurado, J. F.. Universidad Nacional de Colombia; ColombiaFil: Vargas Hernández, C.. Universidad Nacional de Colombia; Colombi

    The Effect of Pre-Harvest Application of Pectic Oligosaccharides and Abscisic Acid on Technological Ripening and Anthocyanin Profile of ‘Syrah’ Must and Grapes Grown in a Warm Climate

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    The progressive increase of environmental temperature as a consequence of climate change is a challengefor the wine industry. Elevated temperatures during grape ripening affect the development of grape skincolor by inhibiting the synthesis of pigments and promoting their degradation, which causes an imbalancein the chromatic quality of must and red wine. The application of pectic oligosaccharides (POs) and abscisicacid (ABA) triggers the phenylpropanoid pathway and increases the color index in grapes. Since the atharvestpigments and phenolic compounds are determinant for wine quality, this work addressed the preharvestapplication of POs and ABA as an in-field strategy for improving the quality of Syrah must andgrapes grown in a warm climate. The color development, physicochemical parameters, phenolic content,and pigments in berries and must were evaluated. Results showed POs and ABA improved berry colordevelopment and anthocyanin content during ripening. Musts from POs-treated berries exhibited thehighest phenols concentration and the most intense color, related to higher chroma values and anthocyanincontent, particularly delphinidin, petunidin, and malvidin 3-glucosides, while ABA improved must tonalityby reducing the hue angle. In summary, POs and ABA application at veráison, differentially modulatedthe technological ripening of Syrah grapes and can be an alternative to conventional agrochemicals topreserve the quality of musts elaborated from grapes grown in warm climates, by increasing the content ofphenolic compounds and enhancing berry skin color development through the differential accumulationof anthocyanins

    The DNA methylome of inflammatory bowel disease (IBD) reflects intrinsic and extrinsic factors in intestinal mucosal cells

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    Abnormal DNA methylation has been described in human inflammatory conditions of the gastrointestinal tract, such as inflammatory bowel disease (IBD). As other complex diseases, IBD results from the balance between genetic predisposition and environmental exposures. As such, DNA methylation may be the consequence (and potential effector) of both, genetic susceptibility variants and/or environmental signals such as cytokine exposure. We attempted to discern between these two non-excluding possibilities by performing a combined analysis of published DNA methylation data in intestinal mucosal cells of IBD and control samples. We identified abnormal DNA methylation at different levels: deviation from mean methylation signals at site and region levels, and differential variability. A fraction of such changes is associated with genetic polymorphisms linked to IBD susceptibility. In addition, by comparing with another intestinal inflammatory condition (i.e., coeliac disease) we propose that aberrant DNA methylation can also be the result of unspecific processes such as chronic inflammation. Our characterization suggests that IBD methylomes combine intrinsic and extrinsic responses in intestinal mucosal cells, and could point to knowledge-based biomarkers of IBD detection and progression.This work was supported by the Agence Nationale de Recherches sur le SIDA et les Hépatites Virales [ANRS, Reference No. ECTZ47287 and ECTZ50137]; Institut National du Cancer (FR) [PLBIO 2017] (project: T cell tolerance to microbiota and colorectal cancers), and Ligue Contre le Cancer (FR) [AAP 2018]; NF is partially funded by the Basque Department of Health [project 2018/111086]

    CARACTERIZACIÓN SISMOTECTÓNICA REGIONAL PRELIMINAR DE UN SECTOR DEL PIEDEMONTE LLANERO COLOMBIANO: CORREDOR SAN JUAN DE ARAMA – CUMARAL,META

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      With the regional tectonic scenario determination carried out with remote sensors, secondary information and field observations, be determined that the faults related to the Eastern Frontal Fault System - EFFS, obeys to a geometry of shortcut planes with maximum longitudes of 30 km, these represent thrust faults that limit to the Andean basement with the South American plate. Also with the support of the historical seismicity and instrumental seismicity registration of the RSNC for the period 1993 - 2001, low seismic activity was determined between 3º and 4º N, and moderate seismic activity to the south of this latitude. This sector of EFFS is composed by listric fault type with low dip angle toward depth under compression stress regime and it seismicity obeys to stress release of these planes in the contact area where the basements converge. The maximum magnitude estimated is M ≥ 6,0 with 5 - 30 km depth hypocenters. However the low previous seismological information and few studies in these faults yet hinder the realization of earthquake prediction in probabilistic sense for these.   Key Words: Andean Eastern Cordillera Foothill, Eastern Frontal Fault System, Geotectonics, Seismicity, Seismotectonics    Con la determinación del escenario tectónico regional realizado con sensores remotos, información secundaria y observaciones de campo, se ha encontrado que las fallas relacionadas al Sistema de Fallas de la Falla Frontal de la Cordillera Oriental   - SFFFCO, obedecen a una geometría de planos muy seccionados con longitudes máximas de 30 km que representan fallas de cabalgamiento que limitan al basamento Andino con la placa suramericana. Con el apoyo de la sismicidad histórica y del registro instrumental de la RSNC para el período 1993 - 2001, se determinó igualmente poca actividad sísmica entre los 3º y 4º N, y una actividad moderada al sur de esta latitud. Este sector del SFFFCO se caracteriza por presentar planos de tipo lístrico bajo régimen compresivo cuyo buzamiento decrece en ángulo hacía profundidad y la sismicidad obedece a la liberación de esfuerzos de estos planos en la zona de contacto donde convergen los basamentos. La magnitud máxima posible esperada es M ≥ 6,0, con hipocentros que oscilan entre 5 y 30 km Sin embargo la baja información sismológica y los pocos estudios realizados en estas fallas todavía impiden realizar la estimación en el sentido probabilístico de los periodos intersísmicos en estas.   Palabras Clave: Piedemonte Llanero colombiano, Sistema de Fallas de la Falla Frontal de de la Cordillera Oriental, Geotectónica,  Sismicidad, Sismotectónica.     &nbsp

    CARACTERIZACIÓN SISMOTECTÓNICA REGIONAL PRELIMINAR DE UN SECTOR DEL PIEDEMONTE LLANERO COLOMBIANO: CORREDOR SAN JUAN DE ARAMA – CUMARAL,META

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      With the regional tectonic scenario determination carried out with remote sensors, secondary information and field observations, be determined that the faults related to the Eastern Frontal Fault System - EFFS, obeys to a geometry of shortcut planes with maximum longitudes of 30 km, these represent thrust faults that limit to the Andean basement with the South American plate. Also with the support of the historical seismicity and instrumental seismicity registration of the RSNC for the period 1993 - 2001, low seismic activity was determined between 3º and 4º N, and moderate seismic activity to the south of this latitude. This sector of EFFS is composed by listric fault type with low dip angle toward depth under compression stress regime and it seismicity obeys to stress release of these planes in the contact area where the basements converge. The maximum magnitude estimated is M ≥ 6,0 with 5 - 30 km depth hypocenters. However the low previous seismological information and few studies in these faults yet hinder the realization of earthquake prediction in probabilistic sense for these.   Key Words: Andean Eastern Cordillera Foothill, Eastern Frontal Fault System, Geotectonics, Seismicity, Seismotectonics    Con la determinación del escenario tectónico regional realizado con sensores remotos, información secundaria y observaciones de campo, se ha encontrado que las fallas relacionadas al Sistema de Fallas de la Falla Frontal de la Cordillera Oriental   - SFFFCO, obedecen a una geometría de planos muy seccionados con longitudes máximas de 30 km que representan fallas de cabalgamiento que limitan al basamento Andino con la placa suramericana. Con el apoyo de la sismicidad histórica y del registro instrumental de la RSNC para el período 1993 - 2001, se determinó igualmente poca actividad sísmica entre los 3º y 4º N, y una actividad moderada al sur de esta latitud. Este sector del SFFFCO se caracteriza por presentar planos de tipo lístrico bajo régimen compresivo cuyo buzamiento decrece en ángulo hacía profundidad y la sismicidad obedece a la liberación de esfuerzos de estos planos en la zona de contacto donde convergen los basamentos. La magnitud máxima posible esperada es M ≥ 6,0, con hipocentros que oscilan entre 5 y 30 km Sin embargo la baja información sismológica y los pocos estudios realizados en estas fallas todavía impiden realizar la estimación en el sentido probabilístico de los periodos intersísmicos en estas.   Palabras Clave: Piedemonte Llanero colombiano, Sistema de Fallas de la Falla Frontal de de la Cordillera Oriental, Geotectónica,  Sismicidad, Sismotectónica.     &nbsp

    Machine-learning-corrected quantum dynamics calculations

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    Quantum scattering calculations for all but low-dimensional systems at low energies must rely on approximations. All approximations introduce errors. The impact of these errors is often difficult to assess because they depend on the Hamiltonian parameters and the particular observable under study. Here, we illustrate a general, system and approximation-independent, approach to improve the accuracy of quantum dynamics approximations. The method is based on a Bayesian machine learning (BML) algorithm that is trained by a small number of rigorous results and a large number of approximate calculations, resulting in ML models that accurately capture the dependence of the dynamics results on the quantum dynamics parameters. Most importantly, the present work demonstrates that the BML models can generalize quantum results to different dynamical processes. Thus, a ML model trained by a combination of approximate and rigorous results for a certain inelastic transition can make accurate predictions for different transitions without rigorous calculations. This opens the possibility of improving the accuracy of approximate calculations for quantum transitions that are out of reach of rigorous scattering calculations.Comment: 6 pages, 4 figure

    Chronic lymphocytic leukemia patients with IGH translocations are characterized by a distinct genetic landscape with prognostic implications

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    Chromosome 14q32 rearrangements/translocations involving the immunoglobulin heavy chain (IGH) are rarely detected in chronic lymphocytic leukemia (CLL). The prognostic significance of the IGH translocation is controversial and its mutational profile remains unknown. Here, we present for the first time a comprehensive next-generation sequencing (NGS) analysis of 46 CLL patients with IGH rearrangement (IGHR-CLLs) and we demonstrate that IGHR-CLLs have a distinct mutational profile with recurrent mutations in NOTCH1, IGLL5, POT1, BCL2, FBXW7, ZMYM3, MGA, BRAF and HIST1H1E genes. Interestingly, BCL2 and FBXW7 mutations were significantly associated with this subgroup and almost half of BCL2, IGLL5 and HISTH1E mutations reported were previously identified in non-Hodgkin lymphomas. Notably, IGH/BCL2 rearrangements were associated with a lower mutation frequency and carried BCL2 and IGLL5 mutations, while the other IGHR-CLLs had mutations in genes related to poor prognosis (NOTCH1, SF3B1 and TP53) and shorter time to first treatment (TFT). Moreover, IGHR-CLLs patients showed a shorter TFT than CLL patients carrying 13q-, normal fluorescence in situ hybridization (FISH) and +12 CLL, being this prognosis particularly poor when NOTCH1, SF3B1, TP53, BIRC3 and BRAF were also mutated. The presence of these mutations not only was an independent risk factor within IGHR-CLLs, but also refined the prognosis of low-risk cytogenetic patients (13q-/normal FISH). Hence, our study demonstrates that IGHR-CLLs have a distinct mutational profile from the majority of CLLs and highlights the relevance of incorporating NGS and the status of IGH by FISH analysis to refine the risk-stratification CLL model

    Econometric analysis of the industrial growth determinants in Colombia

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    An econometric study is carried out using a panel data model with fixed effects to identify the industrial development determinants in Colombia during the term 2005–2015. The database used in the study corresponds to World Bank and the Colombian state. The determinants of industrial growth identified at the theoretical level that allow the enhancement of productive capacities to face foreign competition in Colombia are: innovation; networks of innovations and knowledge among companies and organizations; the interest rate; the capital-product ratio, the unit labor cost; and the exchange rate. The amount invested in scientific, technological and innovation activities by industrial group is the only variable that is not significant in the model
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