On the X-ray Emission from Massive Star Clusters and their Evolving Superbubbles

The X-ray emission properties from the hot thermalized plasma that results from the collisions of individual stellar winds and supernovae ejecta within rich and compact star clusters are discussed. We propose a simple analytical way of estimating the X-ray emission generated by super star clusters and derive an expression that indicates how this X-ray emission depends on the main cluster parameters. Our model predicts that the X-ray luminosity from the star cluster region is highly dependent on the star cluster wind terminal speed, a quantity related to the temperature of the thermalized ejecta.We have also compared the X-ray luminosity from the SSC plasma with the luminosity of the interstellar bubbles generated from the mechanical interaction of the high velocity star cluster winds with the ISM.We found that the hard (2.0 keV - 8.0 keV) X-ray emission is usually dominated by the hotter SSC plasma whereas the soft (0.3 keV - 2.0 keV) component is dominated by the bubble plasma. This implies that compact and massive star clusters should be detected as point-like hard X-ray sources embedded into extended regions of soft diffuse X-ray emission. We also compared our results with predictions from the population synthesis models that take into consideration binary systems and found that in the case of young,massive and compact super star clusters the X-ray emission from the thermalized star cluster plasma may be comparable or even larger than that expected from the HMXB population.Comment: 24 pages, 8 figures, Accepted for publication in The Astrophysical Journa

Propuesta de criterios de aceptación o rechazo de testigos de hormigón proyectado utilizado en fortificación de túneles mineros y civiles

Tesis (Ingeniero Constructor)El presente trabajo, además de señalar de manera sistemática un marco conceptual y teórico acerca de lo que es el hormigón proyectado y cada uno de los factores que lo marginan debido a la escasa información en Chile, propone criterios de aceptación o rechazo de los testigos de hormigón proyectado utilizados en fortificación de túneles mineros y civiles, considerando que la actual normativa chilena evalúa los testigos a partir de parámetros convenidos específicamente para hormigón estructural. Para esto, se dispuso de un conjunto de muestras de testigos utilizados en minería a los que se evaluó por medio de criterios utilizados en Austria y Noruega; países con alta experiencia en fortificación de túneles y, a partir de dichas evaluaciones, se efectuó la propuesta basada en datos reales de resistencia de testigos. Además, se establece una correlación funcional entre resistencias reales, obtenidas a partir de testigos, y potenciales, obtenidas a través de probetas, con el fin de conocer el comportamiento real de la evolución de las resistencias a compresión a partir de muestras ensayadas en laboratorio. Finalmente, se concluye estableciendo propuestas para distintas cantidades de muestra basados en indicadores estadísticos y empíricos.The present research, is focus on theoretical frame about what shotcrete is and the factors that exclude due to limited information in Chile, propose criteria of acceptance and rejection of shotcrete cores used in mining an civil tunneling, considering Chilean standarization evaluates concrete cores for structural concrete. Aforementioned, taken an amount of core samples using in mining which assessed by Austrian and Norwegian criteria; countries with high experience in fortification tunnels and, from these evaluations, the proposal based on actual data resistance of core of was made. In addition, a functional correlation between actual and potential resistance, obtained from core of and obtained through samples, in order to know the actual behavior of the evolution of compressive strength from samples tested in the laboratory is established. Finally, it is concluded establishing proposals for different amount of sample based on statistical and empirical indicators

Fruit Localization and Environment Perception for Strawberry Harvesting Robots

This work presents a machine vision system for the localization of strawberries and environment perception in a strawberry-harvesting robot for use in table-top strawberry production. A deep convolutional neural network for segmentation is utilized to detect the strawberries. Segmented strawberries are localized through coordinate transformation, density base point clustering and the proposed location approximation method. To avoid collisions between the gripper and fixed obstacles, the safe manipulation region is limited to the space in front of the table and underneath the strap. Therefore, a safe region classification algorithm, based on Hough Transform algorithm, is proposed to segment the strap masks into a belt region in order to identify the pickable strawberries located underneath the strap. Similarly, a safe region classification algorithm is proposed for the table, to calculate its points in 3D and fit the points onto a 3D plane based on the 3D point cloud, so that pickable strawberries in front of the table can be identified. Experimental tests showed that the algorithm could accurately classify ripe and unripe strawberries and could identify whether the strawberries are within the safe region for harvesting. Furthermore, harvester robot’s optimized localization method could accurately locate the strawberry targets with a picking accuracy rate of 74.1% in modified situations

Pentadienyl Complexes of Alkali Metals: Structure and Bonding

A systematic density functional study of the structure and bonding in the alkali-metal pentadienyl complexes C5H7E (E = Li-Cs) and their analogues derived from the 2,4-dimethylpentadienyl ligand is performed. The bonding in these structures has been analyzed in some detail with reference to molecular orbital analysis, and energy partition analysis, obtained by density functional calculations. An energy decomposition analysis indicates that the electrostatic interaction is the main factor to be considered in the stabilization of the gas-phase complexes we have studied. The stability of the U-shaped minimum energy structure decreases (the potential energy surface becomes more shallow) as the metal atom gets larger. We trace this behavior to a weakening of the metal–ligand binding due to the increasing diffuseness of the metal p orbitals on going down group 1. A significant pyramidalization at the terminal carbons in the coordinate U-shaped structure correlates with the strength of the metal–ligand binding. Initial results for the structural preferences of the complexes in solution for the lithium pentadienyl complex are examined in view of contrary experimental data. There still remains plenty of work to be done in modeling metal complexes in solution, and we suggest a way forward

Biosorption kinetics of Cd(II), Cr(III) and Pb(II) in aqueous solutions by olive stone

A by-product from olive oil production, olive stone, was investigated for the removal of Cd (II), Cr (III) and Pb (II) from aqueous solutions. The kinetics of biosorption are studied, analyzing the effect of the initial concentration of metal and temperature. Pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models have been used to represent the kinetics of the process and obtain the main kinetic parameters. The results show that the pseudo-second order model is the one that best describes the biosorption of the three metal ions for all the range of experimental conditions investigated. For the three metal ions, the maximum biosoption capacity and the initial biosorption rate increase when the initial metal concentration rises. However, the kinetic constant decreases when the initial metal concentration increases. The temperature effect on biosorption capacity for Cd (II) and Cr (III) is less significant; however, for Pb (II) the effect of temperature is more important, especially when temperature rises from 25 to 40ºC. The biosorption capacity at mmol/g of olive stone changes in the following order: Cr>Cd>Pb. Thus, for an initial concentration of 220 mg/ℓ, a maximum sorption capacity of 0.079 mmol/g for Cr (III), 0.065 mmol/g for Cd (II) and 0.028 mmol/g for Pb (II) has been obtained.The authors are grateful to the Ministerio de Educación y Ciencia for the financial support received (Projet CTM2005-03957/TECNO) for the realization of this work

Genetic diversity of Bm86 sequences in Rhipicephalus (Boophilus) microplus ticks from Mexico: analysis of haplotype distribution patterns

Artículo científico derivado de Tesis doctoral de Saúl Gabriel Martínez ArzateBackground: Ticks are a problem for cattle production mainly in tropical and subtropical regions, because they generate great economic losses. Acaricides and vaccines have been used to try to keep tick populations under control. This has been proven difficult given the resistance to acaricides and vaccines observed in ticks. Resistance to protein rBm86-based vaccines has been associated with the genetic diversity of Bm86 among the ectoparasite’s populations. So far, neither genetic diversity, nor spatial distribution of circulating Bm86 haplotypes, have been studied within the Mexican territory. Here, we explored the genetic diversity of 125 Bm86 cDNA gene sequences from R. microplus from 10 endemic areas of Mexico by analyzing haplotype distribution patterns to help in understanding the population genetic structure of Mexican ticks. Results: Our results showed an average nucleotide identity among the Mexican isolates of 98.3%, ranging from 91.1 to 100%. Divergence between the Mexican and Yeerongpilly (the Bm86 reference vaccine antigen) sequences ranged from 3.1 to 7.4%. Based on the geographic distribution of Bm86 haplotypes in Mexico, our results suggest gene flow occurrence within different regions of the Mexican territory, and even the USA. Conclusions: The polymorphism of Bm86 found in the populations included in this study, could account for the poor efficacy of the current Bm86 antigen based commercial vaccine in many regions of Mexico. Our data may contribute towards designing new, highly-specific, Bm86 antigen vaccine candidates against R. microplus circulating in Mexico.SIEAE UAEM FES

Afectación del aprendizaje en los alumnos ante el Covid-19

En la actualidad nos encontramos en un momento de “crisis” en el mundo, en todos los aspectos de la vida como lo es la educación, la familia, la economía, el bienestar y la salud. Cualquiera de estas variantes se ha visto afectada por la actual enfermedad Covid-19 de una manera en la que se ha tenido que cambiar la dinámica de las cosas completamente, a los estudiantes les tocó vivir un cambio en la manera de aprendizaje ya que todo ha sido realizado en una modalidad en línea. La presente investigación tiene por objetivo, observar como el alumno ha sido afectado en su aprendizaje y determinar la vulnerabilidad y el sentir emocional del estudiante referente a como se desarrolla en la actualidad su vida académica derivado de la pandemia, la metodología utilizada es de tipo cuantitativo y cualitativo, deductivo, no experimental; aplicando un instrumento tipo encuesta y obteniendo como principales resultados que el encierro y la falta de socialización puede traer serias consecuencias en la salud mental de los estudiantes universitarios

Polymetallic nanoparticles in pyrite from massive and stockwork ores of VMS deposits of the Iberian Pyrite Belt

This paper reports the first-ever study on nanoscale mineralogy in pyrite from the volcanogenic massive sulfide (VMS) deposits of the Iberian Pyrite Belt, southwestern Iberian Peninsula. It targeted colloform-textured grains formed at low temperature in the distal part of a polymetallic (Pb-Zn) massive sulfide lens hosted in felsic volcanoclastic rocks from the Masa Valverde deposit, and euhedral-textured grains (re)-deposited by higher temperature fluids in the Co-Au rich stockwork hosted in black shales of the Filón Norte orebody of the Tharsis deposit. The results acquired by a combination of techniques for mineral microanalysis and characterization (i.e., reflected light, FE-SEM, EPMA, LA-ICP-MS, HRTEM-STEM and TEM-EDS) show that trace amounts of metals (Au, Ag, As, Pb, Sb, Cu, Co) are incorporated as both lattice-bound and into nanoparticles (NPs). The mode of occurrence is strongly related with the evolutionary history of the mineralization. In the colloform pyrite collected from the massive sulfide lens, a rhythmic banding/oscillatory zonation with up to 3 wt% As, 5,000 ppm Pb, 1,070 ppm Sb and 750 ppm Cu is defined by the coexistence of several nano-sized layers (5 to 100 nm) and NPs (<100 nm) containing all these metals. The NPs include galena [PbS], tetrahedrite [(Cu,Fe)12Sb4S13)] and arsenopyrite [FeAsS] that exhibit euhedral and less frequently anhedral (i.e., droplet-like) morphologies being both randomly and preferentially oriented with respect to As-rich pyrite bands they are usually associated with. These features suggest formation of the NPs via direct deposition from the hydrothermal fluid(s) or low-temperature melts entrained in them as well as exsolution of trace elements originally dissolved in the As-rich pyrite structure. Additionally, some of these NPs are connected to late fractures disrupting the chemical zoning in colloform pyrite documenting a third genetic type of NPs related to late infiltration of fluids post-dating pyrite formation. In contrast, euhedral pyrite from the stockwork form well-developed homogeneous grains with discrete porous areas relatively depleted in Fe (45.20 wt%), and As (8,800 ppm) but enriched in Co (5,900 ppm). At the nanoscale, Co-enriched domains show patchy zoning defined by irregular distribution of Co– and As-rich bands of 200–500 nm in thickness. These nanometer Co– and As-rich bands are often disrupted by micron-to-nano-sized polycrystalline Au-Ag-Hg particles that fill voids in porous areas. Contact morphology anatomy between Co-rich pyrite and inclusions suggests that the Au-Ag-Hg particles are negative crystals occupying spaces originated in pyrite by coupled dissolution-reprecipitation reaction. Likewise, HRTEM observations along such pyrite-inclusion contacts show the existence of polycrystalline matrices in both pyrite and Au-Ag-Hg inclusions, the former consisting of nano-sized domains of arsenian pyrite and/or arsenopyrite in As-free pyrite and the Au-Ag-Hg inclusions made up of multiple crystal domains including nano-crystallites of Au0/Ag0 or electrum. Recognition of crystalline nanodomains and NPs in these polycrystalline matrices raises the possibility that Au NPs or nanomelts already present in the hydrothermal fluid catalyzed the formation of these heterogeneous crystals

Nanomineralogía de metales traza en piritas de depósitos VMS de la Faja Pirítica Ibérica

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

GameGround

El presente proyecto reside en plantear una idea de negocio, el cual sea rentable y pueda otorgar beneficios a sus fundadores quienes, dentro de la organización, son los socios encargados del manejo interno. El proyecto recibe el nombre de GameGround, es una academia que brinda el servicio de enseñanza de técnicas de videojuegos con el fin de mejorar las habilidades del público objetivo interesado. Gameground está dirigido a niños y jóvenes entre 13 y 25 años que sientan pasión por ser parte del mundo gaming, ellos recibirán el entrenamiento de un coach especializado. El coach se encargará de evaluar las partidas e indicar los puntos fuertes y débiles de cada uno de sus alumnos dependiendo del tipo de juego, siendo 10 personas la cantidad máxima de alumnos matriculados por horario. Para llevar a cabo el trabajo se ha tenido en cuenta el crecimiento de la industria en Perú ya que según la revista virtual “El mundo empresarial” esta será de un 19.76%, estimando un ingreso de USD 191 millones para el año 2024.This project consists in develop a business idea, which have to be profitable and can provide benefits to its founders who, within the organization, are the partners in charge of internal management. The project is called GameGround, it is an academy that provides the service of teaching videogame techniques in order to improve the skills of the interested target audience. GameGround is aimed at children and young people between 13 and 25 years old who feel a passion to be part of the gaming world, they will receive the training by a specialized coach. The coach will be in charge of evaluating the lessons and indicating the strengths and weaknesses of each of his students according to the type of game, with 10 people being the maximum number of students enrolled per schedule. To carry out the work, the growth of the industry in Peru has been taken into account, because according to the virtual magazine "The business world", this will be 19.76%, estimating an income of USD 191 million for the year 2024.Trabajo de investigació