Few-body decay and recombination in nuclear astrophysics

Three-body continuum problems are investigated for light nuclei of astrophysical relevance. We focus on three-body decays of resonances or recombination via resonances or the continuum background. The concepts of widths, decay mechanisms and dynamic evolution are discussed. We also discuss results for the triple $\alpha$ decay in connection with $2^+$ resonances and density and temperature dependence rates of recombination into light nuclei from $\alpha$-particles and neutrons.Comment: 9 pages, 8 figures. Proceedings of the 21st European Few Body Conference held in Salamanca (Spain) in August-September 201

Direct and sequential radiative three-body reaction rates at low temperatures

We investigate the low-temperature reaction rates for radiative capture processes of three particles. We compare direct and sequential capture mechanisms and rates using realistic phenomenological parametrizations of the corresponding photodissociation cross sections.Energy conservation prohibits sequential capture for energies smaller than that of the intermediate two-body structure. A finite width or a finite temperature allows this capture mechanism. We study generic effects of positions and widths of two- and three-body resonances for very low temperatures. We focus on nuclear reactions relevant for astrophysics, and we illustrate with realistic estimates for the $\alpha$-$\alpha$-$\alpha$ and $\alpha$-$\alpha$-$n$ radiative capture processes. The direct capture mechanism leads to reaction rates which for temperatures smaller than 0.1 GK can be several orders of magnitude larger than those of the NACRE compilation.Comment: To be published in European Physical Journal

Els fars davanters a ull de càmara

La contínua innovació en els sistemes d'il·luminació dels automòbils comporta també una millora en els sistemes d'avaluació. Aquests estan basats en la comparació dinàmica, és a dir, que siguin els propis experts o usuaris qui comprovin la qualitat dels fars durant una sèrie de proves de conducció. L'inconvenient d'aquesta mena d'avaluació és que resulta força costós, i la capacitat de retenció visual a curt termini de les persones no assegura uns resultats definitius. Per això, el departament de Desenvolupament Elèctric, Il·luminació i Senyalització del Centre Tècnic de SEAT, a Martorell, i el Centre de Visió per Computador de la UAB han ideat un sistema de gravació, del que després es podran visionar els fotogrames i fer-ne la comparació. És necessari però, sincronització i alineació espacial entre els fotogrames per ajustar correctament els resultats a la realitat de la conducció.La continua innovación en los sistemas de iluminación de los automóviles comporta también una mejora en los sistemas de evaluación. Éstos están basados en la comparación dinámica, es decir, que sean los propios expertos o usuarios quienes comprueben la calidad de los faros durante una serie de pruebas de conducción. El inconveniente de este tipo de evaluación es que resulta bastante costoso, y la capacidad de retención visual a corto plazo de las personas no asegura unos resultados definitivos. Por eso, el departamento de Desarrollo Eléctrico, Iluminación y Señalización del Centro Técnico de SEAT, en Martorell, i el Centro de Visión por Computador de la UAB han ideado un sistema de grabación, del que después se podrán visionar los videos y realizar la comparación. Es necesario sin embargo, sincronización y alineación espacial entre los fotogramas para ajustar correctamente los resultados a la realidad de la conducción.Continuous innovation in headlamp systems also implies an improvement in how they are assessed. These assessment systems are based on dynamic comparison, i.e., experts or users themselves assess the quality of headlamps by means of different driving tests. The disadvantages of this type of assessment are the elevated cost and the fact that short-term visual retention does not guarantee definitive results. For this reason, the Department of Electrical, Lighting and Signal Development at SEAT's Technical Centre in Martorell, and Computer Vision Centre of UAB have created a recording system. The frames from these recordings will later be viewed and compared. However, first they will have to be spatially synchronised and aligned in order to adjust the results to real driving situations

Experiences Developing Safe and Fault-Tolerant Tele-Operated Service Robots. A Case Study in Shipyards

Human operators use tele-operated service robots for performing more or less hazardous operations (manipulation of heavy and/or dangerous products) in more or less hostile environments (nuclear reactors, space missions, warehouses, etc). Anyway, independently of the operation, the robot has to interact with both the environment it is working on and with human operators. Therefore, it is essential that the design (which include both software and hardware) of the robot involves no risk, or at least an acceptable level of risk, neither for the operators, nor for the environment nor for the robot itself. Nevertheless, it is not always possible to make a system free of failures in its design or operation. Apart from the risk inherent to the use of the mechanisms themselves, these systems work in hazardous environments, where the probability of the risk is higher than normal. Should a failure happen, its consequences could even involve the loss of human lives. (Neumann, 1994) documents many cases of computer-related failures, such as the Therac-25 (a radiation-therapy device), the missiles shield in Saudi Arabia, etc. Nevertheless, safety aspects are seldom included in the early phases of the system design process from the beginning, even though they are a critic aspect. Generally, safety has to conform and adapt to the already designed system and not vice versa, when it is widely known that safety involves not only the design of the software but also the hardware. Even more, a simple hardware solution can eliminate a hazard or simplify the software design in many situations.This research has been funded by the Spanish CICYT project MEDWSA (TIN2006-15175- C05-02) and the Regional Government of Murcia Séneca Program (02998-PI-05)

Role of rare earth elements and entropy on the anatase-to-rutile phase transformation of TiO2thin films deposited by ion beam sputtering

The role played by oxygen vacancies and rare earth (RE) elements in the anatase-to-rutile (A−R) phase transformation of titanium dioxide (TiO2) is still a matter of controversy. Here, we report the A−R transformation of TiO2 thin solid films as obtained by ion beam sputtering a RE-decorated titanium target in an oxygen-rich atmosphere. The samples correspond to undoped, single-doped (Sm, Tm, and Tb), and codoped (Sm:Tb, Sm:Tm, and Sm:Tb:Tm) TiO2 films. In the as-prepared form, the films are amorphous and contain ∼0.5 at. % of each RE. The structural modifications of the TiO2 films due to the RE elements and the annealing treatments in an oxygen atmosphere are described according to the experimental results provided by Raman scattering, X-ray photoelectron spectroscopy, and optical measurements. The A−R transformation depends on both the annealing temperature and the characteristics of the undoped, single-doped, and codoped TiO2 films. As reported in the literature, the A−R transformation can be inhibited or enhanced by the presence of impurities and is mostly related to energetic contributions. The experimental results were analyzed, considering the essential and stabilizing role of the entropy of mixing in the A−R transformation due to the introduction of more and multiple quantum states originated in vacancies and impurities in the anatase phase.Fil: Scoca, Diego L.S.. Universidade Estadual de Campinas; BrasilFil: Cemin, Felipe. Universidade Estadual de Campinas; BrasilFil: Aldabe, Sara Alfonsina. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Figueroa, Carlos A.. Universidade de Caxias Do Sul.; BrasilFil: Zanatta, Antonio R.. Universidade de Sao Paulo; BrasilFil: Alvarez, Fernando. Universidade Estadual de Campinas; Brasi

Los estudios afroamericanos y africanos en América Latina: herencia, presencia y visiones del otro

Este libro se propone reflejar el estado de la cuestión acerca de la enseñanza y la investigación sobre África y su diáspora en América Latina. Producto de un encuentro convocado por el Programa Sur-Sur de CLACSO en Salvador de Bahía en el año 2006, donde académicos de muy diversas áreas y de diferentes países de América Latina debatieron sobre nuevos abordajes y líneas de investigación, y sobre la enseñanza y difusión de estas temáticas. Esta obra nos introduce desde una perspectiva pluralista y multifocal de la realidad en campos no tradicionales de la academia, identificando trayectorias, impulsos renovadores, influencias externas y paradigmas propios.Indice Prefacio Maria José Becerra y Diego Buffa Los estudios sobre África y Afroamérica en América Latina. El estado del arte. Gladis Lechini Parte I Estudios Afroamericanos O racismo brasileiro em questão: temas relevantes no debate recente Paula Cristina da Silva Barreto História e historiografia do trabalhador esclavizado no RS: 1819-2006 Mario Maestri A abolição do Comércio Atlãntico de Escravos e os Africanos Livres no Brasil. Ana Flavio Cicchelli Pires De la desaparición de los negros a la reaparición de los afrodescendientes:comprendiendo las políticas de las identidades negras, las clasificaciones raciales y de su estudio en Argentina. Alejandro Frigerio Estudios sobre esclavitud en Córdoba: análisis y perspectivas. Maria José Becerra La historiografía paraguaya y los afrodescendientes. Ignacio Telesca Las raíces del olvido. Un estado de la cuestión sobre el estudio de las poblaciones de origen africano en México. Salvador Vásquez Fernández El que no tiene de inga tiene de mandinga. Género, Etnicidad y Sexualidad en los Estudios Históricos-Antropológicos Afroperuanos. Fátima Valdivia del Río Música, artes performáticas y el campo de las relaciones raciales. Área de estudios de la presencia africana en América Latina. Luis Ferreira Makl Parte II. Estudios sobre África O Ensino e a Pesquisa sobre África no Brasil e a Lei 10.639 Luena Nascimento Nunes Pereira Os estudos africanos no Brasil Um estudo de caso: o CEAA José María Nunes Pereira La enseñanza de la historia de África en Cuba. Aproximación a sus presupuestos teóricos y metodológicos. M. Elena Álvarez Acosta Estudios africanos en Colombia desde Ciencias Políticas y Sociales. Maguemati Wabgou Pasado y presente en los estudios e investigaciones sobre África en Argentina. Diego Buffa Estudios sobre África desde Argentina. Los aportes de la Universidad de Buenos Aires y de la Universidad Nacional del Luján. Marisa Pineau La enseñanza y la investigación sobre África y Afroamérica de la Universidad Nacional de La Plata-Argentina. Marta Maffia Los estudios sobre el Norte de África en Brasil y Argentina: reflexiones en torno a un espacio residual. Juan José Vagni La perspectiva Iberoamericana Consideraciones sobre estudios afroamericanos y africanos en Iberoamérica. Luis Beltrá

COVID-19, mental health and its relationship with workplace accidents

The general objective of this article is to show the relationship that exists in the COVID-19 pandemic, the mental health of people and the propensity for work-related accidents in companies. Various results are shown that detail how COVID-19 has generated and is generating mental alterations in people such as post-traumatic stress disorder, PTSD for its acronym in English. Likewise, data are presented that report the influence of mental health as a precursor to workplace accidents in different industries, with which it can be concluded that COVID-19 needs a comprehensive approach in companies to prevent it from negatively impacting workers and they end up accident during their daily work. Some concrete actions are proposed to promote and avoid in companies so that workers can be better managed in times of a COVID-19 pandemic.Campus Lima Centr

Testing postcombustion CO2 capture with CaO in a 1.7 MWt pilot facility

AbstractCalcium looping, CaL, is a new and rapidly developing technology that makes use of CaO as a high temperature regenerable sorbent of CO2. Previous theoretical and lab scale studies have shown that this technology could lead to a substantial reduction in the cost of CO2 capture and energy penalties because heat can be effectively recovered from this high temperature solid looping system. We report in this paper on the first results from a pilot plant designed to demonstrate the viability of postcombustion capture of CO2 using CaL under conditions comparable to those expected in a large scale plant. The pilot includes two interconnected circulating fluidized bed reactors of 15 m height: a CO2 absorber (carbonator) able to treat up to 2400kg/h (equivalent to about 1.7 MWth), and an oxy-fired CFB calciner with a firing power between 1-3 MWth. CO2 capture efficiencies over 90% have been experimentally observed, including continuous operation with highly cycled solids in the system (i.e. with modest CO2 carrying capacities). SO2 capture is shown to be extremely high, with concentrations of SO2 well below 10 ppmv at the exit of the carbonator. Closure of carbon and sulfur balances is satisfactory. These results should be valuable base for model validation and scaling up purposes in future stages of the EU FP7 “CaOling” project, under which this investigation has been carried out