639 research outputs found
Tissue-nonspecific alkaline phosphatase promotes axonal growth of hippocampal neurons
Axonal growth is essential for establishing neuronal circuits during brain development and for regenerative processes in the adult brain. Unfortunately, the extracellular signals controlling axonal growth are poorly understood. Here we report that a reduction in extracellular ATP levels by tissue-nonspecific alkaline phosphatase (TNAP) is essential for the development of neuritic processes by cultured hippocampal neurons. Selective blockade of TNAP activity with levamisole or specific TNAP knockdown with short hairpin RNA interference inhibited the growth and branching of principal axons, whereas addition of alkaline phosphatase (ALP) promoted axonal growth. Neither activation nor inhibition of adenosine receptors affected the axonal growth, excluding the contribution of extracellular adenosine as a potential hydrolysis product of extracellular ATP to the TNAP-mediated effects. TNAP was colocalized at axonal growth cones with ionotropic ATP receptors (P2X7 receptor), whose activation inhibited axonal growth. Additional analyses suggested a close functional interrelation of TNAP and P2X7 receptors whereby TNAP prevents P2X7 receptor activation by hydrolyzing ATP in the immediate environment of the receptor. Furthermore inhibition of P2X7 receptor reduced TNAP expression, whereas addition of ALP enhanced P2X7 receptor expression. Our results demonstrate that TNAP, regulating both ligand availability and protein expression of P2X7 receptor, is essential for axonal development
Microstructure Effects on the Machinability of AM-Produced Superalloys
This paper discusses the microstructure effects on the machinability of Inconel 718 by conducting machining tests on an additively manufactured (AM) workpiece with a strongly textured grain structure and a wrought workpiece incorporating a finer and more equiaxed grain structure. The AM workpiece was produced as a thin tube using Laser Melting Powder Bed Fusion and optimal processing conditions for this alloy. A lathe was used to conduct instrumented orthogonal machining tests on the two workpiece materials under dry cut and coolant conditions using a semisynthetic emulsion coolant. The process parameters studied were feed from 0.05 to 0.15 mm/rev and cutting speed from 60 to 120 m/min with a cut time of 2 sec duration for each process condition. Measures for each process condition included cutting forces in the feed and main cut direction, and images of chip forms were obtained. The grain structures of the workpiece materials were characterized using Electron Back Scattered Diffraction (EBSD). New findings suggest that grain structures can significantly affect the machinability of the superalloy at a higher feed for all cutting speeds studied, and insights into the cause are discussed. Other important findings comment on the effectiveness of the coolant as a lubricant for reducing friction in machining
The influence of methodological procedures on hydrological classification performance
ABSTRACT: Hydrological classification has emerged as a suitable procedure to disentangle the inherent hydrological complexity of river networks. This practice has contributed to determining key biophysical relations in fluvial ecosystems and the effects of flow modification. Thus, a plethora of classification approaches, which agreed in general concepts and methods but differed largely in specific procedures, have emerged in the last decades. However, few studies have compared the implication of applying contrasting approaches and specifications over the same hydrological data. In this work, using cluster analysis and modelling approaches, we classify the entire river network covering the northern third of the Iberian Peninsula. Specifically, we developed classifications of increasing level of detail, ranging from 2 to 20 class levels, either based on raw and normalized daily flow series and using two contrasting approaches to determine class membership: classify-then-predict (ClasF) and predict-thenclassify (PredF). Classifications were compared in terms of
their statistical strength, the hydrological interpretation, the ability to reduce the bias associated with underrepresented parts of the hydrological space and their spatial correspondnece. The results highlighted that both the data processing and the classification strategy largely influenced the classification outcomes and properties, although differences among procedures were not always statistically significant. The normalization of flow data removed the influence of flow magnitude and generated more complex classifications in which a wider range of hydrologic characteristics were considered. The application of the PredF strategy produced, in most of the cases, classifications with higher discrimination ability and presented greater ability to deal with the presence of distinctive gauges in the data set than using the ClasF strategy.This study was partly funded by the Spanish
Ministry of Economy and Competitiveness as part of the project
MARCE (Ref: CTM-2009-07447; http://marce.ihcantabria.es/) and
the Ministry of Agriculture, Food and Environment as part of the
project RECORAM (ref: 132/2010). José Barquín is supported
by a Ramon y Cajal grant (ref: RYC-2011-08313) of the Ministry
of Economy and Competitiveness
Energy levels distribution in supersaturated silicon with titanium for photovoltaic applications
In the attempt to form an intermediate band in the bandgap of silicon substrates to give it the capability to absorb infrared radiation, we studied the deep levels in supersaturated silicon with titanium. The technique used to characterize the energy levels was the thermal admittance spectroscopy. Our experimental results showed that in samples with titanium concentration just under Mott limit there was a relationship among the activation energy value and the capture cross section value. This relationship obeys to the well known Meyer-Neldel rule, which typically appears in processes involving multiple excitations, like carrier capture/emission in deep levels, and it is generally observed in disordered systems. The obtained characteristic Meyer-Neldel parameters were Tmn = 176 K and kTmn = 15 meV. The energy value could be associated to the typical energy of the phonons in the substrate. The almost perfect adjust of all experimental data to the same straight line provides further evidence of the validity of the Meyer Neldel rule, and may contribute to obtain a deeper insight on the ultimate meaning of this phenomenon. (C) 2015 AIP Publishing LLC
Gestión investigativo laboral para estudiantes de la carrera de medicina en el consultorio. Estudio preliminar / Working investigative management for medical students at the medical office: a preliminary study
Con el objetivo de identificar las tendencias existentes acerca de cómo se dirige el PDE de los estudiantes de la Carrera de Medicina de todos los años, a nivel del Consultorio Médico en su componente investigativo laboral, se realizó el presente trabajo utilizando métodos teóricos y empíricos de la investigación, donde empleando el análisis de 2 preguntas en un grupo focal organizado, al respecto, se muestran un número de limitaciones que hacen que la gestión de este proceso sea insuficiente a este nivel, no lográndose la necesaria planificación, organización, regulación y control del proceso, lo cual repercute en la adquisición de las habilidades necesarias por los educandos. Palabras clave: recursos humanos en salud, educación médica, consultorios médicos, investigación. ABSTRACT The present work is aimed at identifying the present trends about how to manage the PDE in medical students at medical office using theoretical and empirical methods for the research using the analysis of 2 questions in a group designed for this purpose . Some limitations as planning, organizations and the control of the process are shown which obstruct the management of this process with some grade of repercussion on the necessary skills for the students.Key words: health manpower, medical education, physicians' offices, research
Gestión investigativo laboral para estudiantes de la carrera de medicina en el consultorio. Estudio preliminar / Working investigative management for medical students at the medical office: a preliminary study
Con el objetivo de identificar las tendencias existentes acerca de cómo se dirige el PDE de los estudiantes de la Carrera de Medicina de todos los años, a nivel del Consultorio Médico en su componente investigativo laboral, se realizó el presente trabajo utilizando métodos teóricos y empíricos de la investigación, donde empleando el análisis de 2 preguntas en un grupo focal organizado, al respecto, se muestran un número de limitaciones que hacen que la gestión de este proceso sea insuficiente a este nivel, no lográndose la necesaria planificación, organización, regulación y control del proceso, lo cual repercute en la adquisición de las habilidades necesarias por los educandos. Palabras clave: recursos humanos en salud, educación médica, consultorios médicos, investigación. ABSTRACT The present work is aimed at identifying the present trends about how to manage the PDE in medical students at medical office using theoretical and empirical methods for the research using the analysis of 2 questions in a group designed for this purpose . Some limitations as planning, organizations and the control of the process are shown which obstruct the management of this process with some grade of repercussion on the necessary skills for the students.Key words: health manpower, medical education, physicians' offices, research
Estructura, logros y desafíos del Grupo de Estudios Didácticos de la Educación Superior en Salud / Structure, achievements and challenges of the Didactic Study Group in the High Education in Health
La Universidad Médica Pinareña, inmersa en dar respuesta a las demandas que el proceso formativo requiere, ha precisado lograr un clima institucional Didáctico - Pedagógico que diera respuesta a la formación de su claustro profesoral para enfrentar los retos que las condiciones actuales demandan, lo que hizo necesario proponer una estrategia de desarrollo que permitiese una estructura funcional de un Grupo de Estudios Didáctico para la Educación Médica, determinando su misión, visión y funciones. Para ello se tomaron en consideración los métodos teóricos y empíricos, que permitieron dar sustento a partir de la detección de los problemas didácticos que se presentaban en la Universidad de Ciencias Médicas Dr. Ernesto Che Guevara de la Serna de Pinar del Río. El trabajo demostró los logros alcanzados por el Grupo durante la etapa que se analiza, estableciendo los desafíos, que como retos, culminarán en paso de Grupo a Centro de Estudios Didácticos de la Educación Médica Superior para las Carreras de la Salud. Palabras Clave: educación médica/métodos, universidades.ABSTRACT Pinar del Rio Medical University is concerned about those demands that the educative process requires and it has created a didactic- pedagogical method for the professorial staff in order to face those challenges demanded by the current conditions, so it was necessary to propose an strategy being able to create a functional structure by a didactic study group in the medical education for determining its purpose, its objective and functions. With this purpose, those theoretical and empirical methods capable of allowing the detection of the didactic problems present in Pinar del Rio "Ernesto Che Guevara de la Serna" Medical School were considered. It was demonstrated the achievements obtained by this group of professors and it was established the challenges that will permit the change from a group to a centre of high medica education for health majors. Key words: medical education/methods, universitie
Estructura, logros y desafíos del Grupo de Estudios Didácticos de la Educación Superior en Salud / Structure, achievements and challenges of the Didactic Study Group in the High Education in Health
La Universidad Médica Pinareña, inmersa en dar respuesta a las demandas que el proceso formativo requiere, ha precisado lograr un clima institucional Didáctico - Pedagógico que diera respuesta a la formación de su claustro profesoral para enfrentar los retos que las condiciones actuales demandan, lo que hizo necesario proponer una estrategia de desarrollo que permitiese una estructura funcional de un Grupo de Estudios Didáctico para la Educación Médica, determinando su misión, visión y funciones. Para ello se tomaron en consideración los métodos teóricos y empíricos, que permitieron dar sustento a partir de la detección de los problemas didácticos que se presentaban en la Universidad de Ciencias Médicas Dr. Ernesto Che Guevara de la Serna de Pinar del Río. El trabajo demostró los logros alcanzados por el Grupo durante la etapa que se analiza, estableciendo los desafíos, que como retos, culminarán en paso de Grupo a Centro de Estudios Didácticos de la Educación Médica Superior para las Carreras de la Salud. Palabras Clave: educación médica/métodos, universidades.ABSTRACT Pinar del Rio Medical University is concerned about those demands that the educative process requires and it has created a didactic- pedagogical method for the professorial staff in order to face those challenges demanded by the current conditions, so it was necessary to propose an strategy being able to create a functional structure by a didactic study group in the medical education for determining its purpose, its objective and functions. With this purpose, those theoretical and empirical methods capable of allowing the detection of the didactic problems present in Pinar del Rio "Ernesto Che Guevara de la Serna" Medical School were considered. It was demonstrated the achievements obtained by this group of professors and it was established the challenges that will permit the change from a group to a centre of high medica education for health majors. Key words: medical education/methods, universitie
Molecular characterization of dissolved organic matter linked to microbial (Bacteria and Archaea) diversity in the main water masses of the Eastern North Atlantic Ocean
The microbe-dissolved organic matter (DOM) interactions include microbial uptake and DOM reworking and release, affecting the composition of the heterogeneous DOM pool. In turns, this distinct DOM composition can select for microbial assemblages. We investigated the diversity of microbial (both Bacteria and Archaea) communities (combining Illumina tag sequencing of 16S rRNA gen -amplicon sequencing variants, ASVs- and metagenomics) and the chemodiversity of dissolved organic molecules (extracted by solid phase extraction and analyzed by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, FT-ICR-MS) in the Eastern North Atlantic Ocean off the Galician coast (43oN, 9o-15oW). Sampling ranged from 100 m to 5000 m, thereby encompassing a wide variety of water masses with contrasting origins and different aging. Applying diversity ecological metrics to both organic compounds and ASVs, we found that microbial diversity and richness were negatively correlated with DOM concentration and chemo-diversity. Besides, our results demonstrated the link between this trend and water mass aging, which enhances biosphere taxonomic diversity but reduces molecular variety. DOM diversity, decreasing along the water mass aging gradient, would likely reflect the persistence of the most refractory molecules, generated as by- product of the DOM degradation by microbes. In two PCoAs based on the metagenomic data, combined PCoA axis 1 and PCoA axis 2, explained the 80% and 20% of the microbial gene ́s structural variability among water masses. The oldest water masses, originated at high latitudes, such as NADW and LDW, were associated to higher abundance of genes involved in metabolism of aromatic compound. Intermediate waters such as ENACWst were related to sulphur/iron/phosphorous metabolism related genes. Surface waters were linked to genes involved in photosynthesis, autotrophy and cell division. Taken together, the observed increase of DOM homogenization along water mass aging was associated to differences in the functional diversity of microbial communities
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