800 research outputs found

    Aportaciones en Ciencias Agronómicas y Ambientales

    Get PDF
    de investigadores e investigadores independientes. En ese sentido, queremos otorgar un reconocimiento a quienes tuvieron la voluntad y el tino de apoyar esta iniciativa sobre trabajos relacionados con la quimica, biología, agronomía y medio ambiente

    Aportaciones en Matemáticas y Química

    Get PDF
    Presenta una serie de trabajos de investigación sobre el título de este libro: El estudio de fenómenos naturales por medio de datos, trae a colación un conjunto de acciones y procedimientos matemáticos que a veces usamos o abusamos de las restricciones no solo de las técnicas de regresión lineal sino también de las no lineales. para la dieta del mexicano. No obstante, el consumo per cápita se ha reducido de 18 kg a menos de 8.5 kg. Puesto que en las últimas décadas, la producción nacional ha disminuido, entre otras causas debido a la reducción de la superficie agrícola por la urbanización, lo cual margina la producción a regiones con condiciones limitantes para la agricultura; lo no atractivo que ha sido trabajar el campo, los siniestros ocasionados por las condiciones naturales (sequías, inundación, heladas tempranas, etc.) que reducen o hacen nulo el rendimiento. Así como Saber cuánto fertilizante se va a aplicar a un cultivo, ha sido desde la aparición de los fertilizantes artificiales o sales inorgánicas una pregunta que los productores hacen a los técnicos agrícolas. Estos responden usando su experiencia y los resultados de los ya muchísimos experimentos de dosis de nutrimentos de muchos cultivos a la fecha. Se han destacado como importantes para determinar la cantidad de nutrimentos que un cultivo necesita: el tipo de cultivo, las temperaturas, la cantidad de agua disponible (temporal o riego), la textura del suelo y su origen y el contenido de nutrimentos. También otros factores son importantes: la pendiente, la distribución de la precipitación durante el ciclo, la cantidad de luz, etc. Entre otros

    Scalable High-Mobility Graphene/hBN Heterostructures

    Full text link
    Graphene-hexagonal boron nitride (hBN) scalable heterostructures are pivotal for the development of graphene-based high-tech applications. In this work, we demonstrate the realization of high-quality graphene-hBN heterostructures entirely obtained with scalable approaches. hBN continuous films were grown via ion beam-assisted physical vapor deposition directly on commercially available SiO2/SiSiO_2/Si and used as receiving substrates for graphene single-crystal matrixes grown by chemical vapor deposition on copper. The structural, chemical, and electronic properties of the heterostructure were investigated by atomic force microscopy, Raman spectroscopy, and electrical transport measurements. We demonstrate graphene carrier mobilities exceeding 10,000cm2/Vs10,000 cm^2/Vs in ambient conditions, 30% higher than those directly measured on SiO2/SiSiO_{2}/Si. We prove the scalability of our approach by measuring more than 100 transfer length method devices over a centimeter scale, which present an average carrier mobility of 7500±850cm2/Vs7500 \pm 850 cm^{2}/Vs. The reported high-quality all-scalable heterostructures are of relevance for the development of graphene-based high-performing electronic and optoelectronic applications

    Galaxy evolution in compact groups I: Revealing a transitional galaxy population through a multiwavelength approach

    Full text link
    Compact groups of galaxies (CGs) show members with morphological disturbances, mainly products of galaxy-galaxy interactions, thus making them ideal systems to study galaxy evolution, in high-density environment. To understand how this environment affects the properties of galaxies, we select a sample of 340 CGs in the Stripe 82 region, for a total of 1083 galaxies, and a sample of 2281 field galaxies as a control sample. By performing a multi-wavelength morphological fitting process using S-PLUS data, we divide our sample into early-type (ETG), late-type (LTG), and transition galaxies using the r-band S\'ersic index and the colour (u-r). We find a bimodal distribution in the plane of the effective radius-S\'ersic index, where a secondary "peculiar" galaxy population of smaller and more compact galaxies is found in CGs, which is not observed in the control sample. This indicates that galaxies are undergoing a morphological transformation in CGs. In addition, we find significant statistical differences in the distribution of specific Star Formation Rate (sSFR) when we compare both environments for LTGs and ETGs. We also find a higher fraction of quenched galaxies and a lower median sSFR in CGs than in the control sample, suggesting the existence of environmental effects favoring the cessation of star formation, regardless of galaxy type. Our results support the notion that CGs promote morphological and physical transformations, highlighting their potential as ideal systems for galaxy pre-processing.Comment: 17 pages, 15 figures. Accepted for publication in MNRA

    Grupo español de cirugía torácica asistida por videoimagen: método, auditoría y resultados iniciales de una cohorte nacional prospectiva de pacientes tratados con resecciones anatómicas del pulmón

    Full text link
    Introduction: our study sought to know the current implementation of video-assisted thoracoscopic surgery (VATS) for anatomical lung resections in Spain. We present our initial results and describe the auditing systems developed by the Spanish VATS Group (GEVATS). Methods: we conducted a prospective multicentre cohort study that included patients receiving anatomical lung resections between 12/20/2016 and 03/20/2018. The main quality controls consisted of determining the recruitment rate of each centre and the accuracy of the perioperative data collected based on six key variables. The implications of a low recruitment rate were analysed for '90-day mortality' and 'Grade IIIb-V complications'. Results: the series was composed of 3533 cases (1917 VATS; 54.3%) across 33 departments. The centres' median recruitment rate was 99% (25-75th:76-100%), with an overall recruitment rate of 83% and a data accuracy of 98%. We were unable to demonstrate a significant association between the recruitment rate and the risk of morbidity/mortality, but a trend was found in the unadjusted analysis for those centres with recruitment rates lower than 80% (centres with 95-100% rates as reference): grade IIIb-V OR=0.61 (p=0.081), 90-day mortality OR=0.46 (p=0.051). Conclusions: more than half of the anatomical lung resections in Spain are performed via VATS. According to our results, the centre's recruitment rate and its potential implications due to selection bias, should deserve further attention by the main voluntary multicentre studies of our speciality. The high representativeness as well as the reliability of the GEVATS data constitute a fundamental point of departure for this nationwide cohort

    Case-Control Analysis of the Impact of Anemia on Quality of Life in Patients with Cancer: A Qca Study Analysis

    Get PDF
    The impact of anemia on the quality of life (QoL) in cancer patients has been studied previously; however, the cut-off point used to define anemia differed among studies, thus providing inconsistent results. Therefore, we analysed the clinical impact of anemia on QoL using the same cut-off point for hemoglobin level to define anemia as that used in ESMO clinical practice guidelines. This post-hoc analysis aimed to determine the impact of anemia on QoL in cancer patients through the European Organization for Research and Treatment of Cancer Quality of life questionnaire version 3.0 (EORTC QLQ-C30) and Euro QoL 5-dimension 3-level (EQ-5D-3L) questionnaire. We found that cancer patients with anemia had significantly worse QoL in clinical terms. In addition, anemic patients had more pronounced symptoms than those in non-anemic patients. Anemia is a common condition in cancer patients and is associated with a wide variety of symptoms that impair quality of life (QoL). However, exactly how anemia affects QoL in cancer patients is unclear because of the inconsistencies in its definition in previous reports. We aimed to examine the clinical impact of anemia on the QoL of cancer patients using specific questionnaires. We performed a post-hoc analysis of a multicenter, prospective, case-control study. We included patients with cancer with (cases) or without (controls) anemia. Participants completed the European Organization for Research and Treatment of Cancer Quality of Life questionnaire version 3.0 (EORTC QLQ-C30) and Euro QoL 5-dimension 3-level (EQ-5D-3L) questionnaire. Statistically significant and clinically relevant differences in the global health status were examined. From 2015 to 2018, 365 patients were included (90 cases and 275 controls). We found minimally important differences in global health status according to the EORTC QLQ-C30 questionnaire (case vs. controls: 45.6 vs. 58%, respectively; mean difference: -12.4, p < 0.001). Regarding symptoms, cancer patients with anemia had more pronounced symptoms in six out of nine scales in comparison with those without anemia. In conclusion, cancer patients with anemia had a worse QoL both clinically and statistically

    The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

    Get PDF
    The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected
    corecore