Metallic slabs: Perturbative treatments based on jellium

We examine first-order perturbative results based on jellium for the surface energy of slabs of simple metals, using various local pseudopotentials (Ashcroft, Heine-Abarenkov and evanescent core). The difference between the pseudopotential and the jellium potential is averaged along the plane parallel to the surface. We compare these perturbative results with those of the stabilized jellium model (a modification of the regular jellium model in which the perturbation appears in the energy functional right from the outset) and with the output of other perturbative and non-perturbative calculations.Comment: 15 pages, 2 figures, to appear in Prog. Surf. Sc

The M_BH-M_star relation of obscured AGNs at high redshift

We report the detection of broad Halpha emission in three X-ray selected obscured AGNs at z=1-2. By exploiting the Halpha width and the intrinsic X-ray luminosity, we estimate their black hole masses, which are in the range 0.1-3x10^9 Msun. By means of multi-band photometric data, we measure the stellar mass of their host galaxy and, therefore, infer their M_BH/M_star ratio. These are the first obscured AGNs at high-z, selected based on their black hole accretion (i.e. on the basis of their X-ray luminosity), that can be located on the M_BH-M_star relation at high-z. All of these obscured high-z AGNs are fully consistent with the local M_BH-M_star relation. This result conflicts with those for other samples of AGNs in the same redshift range, whose M_BH/M_star ratio departs significantly from the value observed in local galaxies. We suggest that the obscured AGNs in our sample are in an advanced evolutionary stage, have already settled onto the local M_BH-M_star relation, and whose nuclear activity has been temporarily revived by recent galaxy interactions.Comment: 4 pages, 2 figures, accepted for publication in A&A Letters, slightly revised discussion on SMG

Efficiency Centered Maintenance of Preheat Train of a Crude Oil Distillation Unit

Nowadays, maintenance is based on the synergistic integration of operational reliability and timely maintenance, which guarantees the required availability and optimal cost. Operational reliability implies producing more, better performance, longer life, and availability. Timely maintenance involves the least time out of service, fewer maintenance costs, fewer operating costs, and less money. In this work, we study the preheating train of a crude distillation unit of a refinery, which processes 994 m3/h, which presents a formation of a foulinglayer inside it. Among the impacts of fouling is the reduction in the effectiveness of heat transfer, the increase in fuel consumption, the increase in CO2 emissions, the increase in maintenance costs, and the decrease in the profit margin of process. An appropriate cleaning program of the surface of the heat exchanger network is necessary to preserve its key performance parameters, preferably close to design values. This paper presents the maintenance method centered on energy efficiency, to plan the intervention of the preheating train equipment maintenance, which considers the economic energy improvement and the cost of the type of maintenance. The method requires the calculation of the fouling evolution from which the global heat transfer coefficient is obtained, and the heat flux is determined as a function of time. It was observed that, as time passes, the resistance provided by fouling increases and that the overall heat transfer coefficient decreases. The energy efficiency centered maintenance has an indicator of economic justification (factor J) that relates the economic-energy improvement achieved when performing maintenance, taking into account the economic effort invested. Depending on the cost of the type of maintenance to be performed, a threshold should be chosen, from which the maintenance activity is justified. The effectiveness values of the heat exchanger (e) and the J indicator are used to form a criticality matrix, which allows prioritizing maintenance activities in each equipment. The planning of the implementation dates of the maintenance of each heat exchanger, from the maintenance method centered on energy efficiency applied to the crude distillation unit's, preheat train, constitutes a contribution in this specific field. The conceptual design of the maintenance method centered on energy efficiency presented in this work is feasible for other heat transfer equipment used in oil refineries and industry in general. The procedure developed uses real operation values, and with its implementation, a saving of 150000 US dollars was achieved. © 2020 ASME

Longitudinal Remote SBRT/SRS Training in Latin America: A Prospective Cohort Study

BACKGROUND: Continuing medical education in stereotactic technology are scarcely accessible in developing countries. We report the results of upscaling a longitudinal telehealth training course on stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS), after successfully developing a pilot course in Latin America. METHODS: Longitudinal training on SBRT and SRS was provided to radiation oncology practitioners in Peru and Colombia at no cost. The program included sixteen weekly 1-hour live conferencing sessions with interactive didactics and a cloud-based platform for case-based learning. Participant-reported confidence was measured in 16 SBRT/SRS practical domains, based on a 1-to-5 Likert scale. Pre- and post-curriculum exams were required for participation credit. Knowledge-baseline, pre- and post-curriculum surveys, overall and single professional-group confidence changes, and exam results were assessed. RESULTS: One hundred and seventy-three radiotherapy professionals participated. An average of 56 (SD ±18) attendees per session were registered. Fifty (29.7%) participants completed the pre- and post-curriculum surveys, of which 30% were radiation oncologists (RO), 26% radiation therapists (RTT), 20% residents, 18% medical physicists and 6% neurosurgeons. Significant improvements were found across all 16 domains with overall mean +0.55 (SD ±0.17, p\u3c0.001) Likert-scale points. Significant improvements in individual competences were most common among medical physicists, RTT and residents. Pre- and post-curriculum exams yielded a mean 16.15/30 (53.8 ± 20.3%) and 23.6/30 (78.7 ± 19.3%) correct answers (p\u3c0.001). CONCLUSION: Longitudinal telehealth training is an effective method for improving confidence and knowledge on SBRT/SRS amongst professionals. Remote continuing medical education should be widely adopted in lower-middle income countries

Estimación de las relaciones genéticas entre razas caprinas españolas y criollas utilizando microsatélites

We have analyzed three Creole goat populations from Peru, Mexico and Chile using microsatellite markers. We have also analyzed the genetic relationship between them and Murciano-Granadina and Malagueña Spanish goat breeds. The average number of alleles per locus was similar in all populations (7.3) except the Chilean Creole (5.1). This Creole goat population has presented the lowest value of observed (Ho) (0.53) and expected (He) heterozygosis (0.59). The Peruvian Creole has presented the highest values of Ho (0.70) and He (0.71). We have found a scarce level of genetic differentiation between goat populations (FST= 0.069) being more important the individual genetic differences due to crossbreed with several breeds. The Peruvian Creole was closed to analyzed Spanish breeds, followed by Mexican Creole. Finally the Chilean Creole was the most distant to the others populations

Characterization and proposals for the improvement of goat production systems of the Peruvian coast

Perú tiene un importante sector caprino con rebaños de aptitud cárnica o mixta. Sin embargo, en los valles de la costa central hay una mayor tendencia a la orientación lechera, alimentando a los animales en base a rastrojos agrícolas. El objetivo de este estudio fue caracterizar las explotaciones de esta zona, para lo cual se entrevistaron 60 ganaderos y se analizaron 39 variables. Se realizó un análisis multivariante seguido de un ANOVA entre los cuatro grupos resultantes del mismo; obteniéndose dos dimensiones que explican el 69.9 % de la varianza. Ocho variables mostraron diferencias significativas: (i) educación del ganadero, los niveles primario y secundario predominaron respectivamente en los Grupos 2 y 3, P<0.05; (ii) superficie de explotación, menos de 0.50 ha a excepción del Grupo 1, P<0.05; (iii) modo de propiedad de la tierra, la propiedad privada fue menor en el Grupo 1, P<0.01; (iv) importancia de las cabras, la producción caprina es la principal actividad del ganadero en los Grupos 3 y 4, P<0.001; (v) número de caprinos, 97 y 80 respectivamente en los Grupos 1 y 4 y menos en el resto; P<0.001); (vii) número de bovinos, 18 y 16 respectivamente en los Grupos 1 y 2, y menos en el resto, P<0.001; y (viii) suministro de alimentos en la granja, no existiendo éste en los Grupos 1 y 4, P<0.01. Para tener continuidad y mejora, estos sistemas de producción caprina deberían reorganizarse de forma global, incrementar el tamaño de las explotaciones y tratar de comercializar productos diferenciados.Peru has an important goat sector, based mainly on mixed or meat purpose herds. Nevertheless, in Peruvian central coast valleys, goats are more oriented to milk purpose, being the animal feeding based on graze crop stubbles. The objective of this study was to characterize farms of this area. Sixty (60) farmers were interviewed and 39 variables were used in the study. A multivariate analysis followed by an ANOVA among the four obtained clusters was conducted. Two dimensions were obtained explaining 69.9 % of variance. Eight variables showed statistical differences: (i) farmer’s education level, primary and secondary level predominate respectively in Clusters 3 and 2, P<0.05); (ii) farm surface area, less than 0.50 ha except in Cluster 1, P<0.05; (iii) type of land ownership, private was lesser in Cluster 1, P<0.01; (iv) importance of goats, goat production was the main farmer activity in Clusters 3 and 4, P<0.001; (v) number of goats, 97 y 80 respectively in Clusters 1 and 4 and less in the other clusters; P<0.001); (vii) number of bovines, 18 and 16 respectively in Clusters 1 and 2 and less in the other clusters, P<0.001; and (viii) feeding supply in the trough, farmers did not supplied feed in Clusters 1 and 4, P<0.01. These production systems should be improved globally for their continuity. Likewise, the holding size increasing would be appropriate and the trading of singular products should be driving

Modulation of receptor cycling by neuron-enriched endosomal protein of 21 kD

Although correct cycling of neuronal membrane proteins is essential for neurite outgrowth and synaptic plasticity, neuron-specific proteins of the implicated endosomes have not been characterized. Here we show that a previously cloned, developmentally regulated, neuronal protein of unknown function binds to syntaxin 13. We propose to name this protein neuron-enriched endosomal protein of 21 kD (NEEP21), because it is colocalized with transferrin receptors, internalized transferrin (Tf), and Rab4. In PC12 cells, NEEP21 overexpression accelerates Tf internalization and recycling, whereas its down-regulation strongly delays Tf recycling. In primary neurons, NEEP21 is localized to the somatodendritic compartment, and, upon N-methyl-d-aspartate (NMDA) stimulation, the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor subunit GluR2 is internalized into NEEP21-positive endosomes. NEEP21 down-regulation retards recycling of GluR1 to the cell surface after NMDA stimulation of hippocampal neurons. In summary, NEEP21 is a neuronal protein that is localized to the early endosomal pathway and is necessary for correct receptor recycling in neurons

Estimation of genetic relationships between Spanish and Creole goat breeds using microsatellite

Ponencia publicada en ITEA, vol.104Se han analizado genéticamente tres poblaciones caprinas Criollas de Perú, México y Chile utilizando marcadores de ADN de tipo microsatélite y se han comparado con las razas españolas Murciano Granadina y Malagueña. Se ha encontrado un número medio de alelos por locus similar en todas las poblaciones (7,3) excepto la población Criolla Chilena que ha mostrado un valor de 5,1, siendo ésta la que ha presentado el valor inferior tanto de heterocigosidad observada (Ho) (0,53) como de esperada (He) (0,59), habiendo sido la Criolla Peruana la que ha presentado los mayores valores (0,70 y 0,71 respectivamente). Se ha encontrado un escaso nivel de diferenciación genética entre las poblaciones (FST = 0,069) siendo las diferencias encontradas debidas a los individuos como consecuencia al cruzamiento indiscriminado con otras razas. La población caprina Criolla de Perú es la que más se aproxima gené- ticamente a las 2 razas españolas analizadas, seguida de la Criolla Mexicana, por último la población criolla Chilena es la que presenta la mayor lejanía genética con el resto de poblaciones estudiadas.We have analyzed three Creole goat populations from Peru, Mexico and Chile using microsatellite markers. We have also analyzed the genetic relationship between them and Murciano-Granadina and Malagueña Spanish goat breeds. The average number of alleles per locus was similar in all populations (7.3) except the Chilean Creole (5.1). This Creole goat population has presented the lowest value of observed (Ho) (0.53) and expected (He) heterozygosis (0.59). The Peruvian Creole has presented the highest values of Ho (0.70) and He (0.71). We have found a scarce level of genetic differentiation between goat populations (FST= 0.069) being more important the individual genetic differences due to crossbreed with several breeds. The Peruvian Creole was closed to analyzed Spanish breeds, followed by Mexican Creole. Finally the Chilean Creole was the most distant to the others populations