First star formation with dark matter annihilation

We include an energy term based on Dark Matter (DM) self-annihilation during the cooling and subsequent collapse of the metal-free gas, in halos hosting the formation of the first stars in the Universe. We have found that the feedback induced on the chemistry of the cloud does modify the properties of the gas throughout the collapse. However, the modifications are not dramatic, and the typical Jeans mass within the halo is conserved throughout the collapse, for all the DM parameters we have considered. This result implies that the presence of Dark Matter annihilations does not substantially modify the Initial Mass Function of the First Stars, with respect to the standard case in which such additional energy term is not taken into account. We have also found that when the rate of energy produced by the DM annihilations and absorbed by the gas equals the chemical cooling (at densities yet far from the actual formation of a proto-stellar core) the structure does not halt its collapse, although that proceeds more slowly by a factor smaller than few per cent of the total collapse time.Comment: 12 pages, 8 figures, 3 tables; replaced with published version after minor change

Event-based MILP models for resource-constrained project scheduling problems

International audienceIn this paper we make a comparative study of several mixed integer linear programming (MILP) formulations for resource-constrained project scheduling problems (RCPSPs). First, we present three discrete and continuous time MILP formulations issued from the literature. Second, instead of relying on the traditional discretization of the time horizon, we propose two original MILP formulations for the RCPSP based on the concept of event : the Start/End formulation and the On/Off formulation. These formulations present the advantage of involving fewer variables than the formulations indexed by time. Because the variables of this type of formulations are not function of the time horizon, we have a better capacity to deal with instances of very large scheduling horizon. We also illustrate our contribution with a series of tests on various types of instances with the three MILP formulations issued from the literature together with our two new formulations, and we draw some conclusions on their use

L'Università dell'innovazione. L'ufficio di trasferimento tecnonolgico dell'Ateneo di Cagliari "Unica Laison Office"

Obiettivi ed organizzazzione dell'ufficio per il trasferimento tecnologico

Evaluation of Performances of Calcined Laterite and Oyster Shell Powder Based Blended Geopolymer Binders

This work consisted in characterizing of calcined laterite and oyster shell powder based blended geopolymer binders. To do this, raw laterite taken from Soa in the city of Yaoundé and oyster shells extracted from Mouanko in the Sanaga-Maritime were initially air-dried, then dried at 105 °C, before being calcined at 500 °C and 200 °C respectively for 2 hours. These samples were subjected to preliminary studies, i.e. determination of their chemical and mineralogical compositions, particle size distributions, densities, as well as thermal analysis for the synthesis of geopolymer binders. X-ray diffractometry, thermal and gravimetric analysis were carried out on the oyster shell powder and laterite, in order to elucidate the time and degree of calcination of the two samples, the evolution of the linear shrinkage, the setting time as well as the compressive and flexural strengths of the geopolymer binders. The results obtained show that oyster shells are rich in CaCO3 and contain crystalline phases, while laterite is rich in silica, iron (FeCO3) and alumina (Al2O3). The geopolymer samples: Lat + 0% oyster shells have a setting time between 125 and 168 min for a compressive strength of about 47 MPa. The peak strength is observed around 15% addition of oyster shell powder, i.e. 53.5 MPa at 28 days with an increased setting time. This strength was decreased from 25 % of addition of oyster shells, despite the increase observed in the setting time. It appears from this study that the addition of 15% oyster shell increases the compressive strength of the geopolymer, but also leads to a considerable decrease in absorption rate. Above this rate, the compressive strength decreases drastically and concomitantly the setting time increases

Comportamiento de los principales indicadores funcionales del área intensiva municipal de Los Palacios

Introduction: the implementation of municipal intensive care areas and their location at the primary health care level has favored the management of critical patients.Objective: to characterize the behavior of the main functional indicators in the municipal intensive care area in Los Palacios during the years 2016 and 2017.Method: a research in health services in a population of 1 422 patients attended in the municipal intensive care area during this period. The summary measures used were qualitative data and odds ratio.Results: male sex predominated (51.5%) and ages from 60 and over (56.9%); cardiovascular diseases were frequent, followed by other diseases, 47.9 % of the patients found good response in the area and only 2.9% died; 88.8% of myocardial infarctions were thrombolyzed, not increasing the risk of death.Conclusions: the municipal intensive area constituted a vital service to care seriously-ill patients, achieving an important response with a decrease of the lethality within the intensive care area.Introducción: la puesta en funcionamiento de las áreas intensivas municipales y su ubicación en el nivel primario de atención ha favorecido el manejo del paciente crítico.Objetivo: caracterizar el comportamiento de los principales indicadores funcionales en el área intensiva municipal de Los Palacios durante los años 2016 y 2017.Método: se trató de una investigación en servicios de salud en una población de 1 422 pacientes atendidos en el área intensiva municipal durante esos años. Se utilizaron medidas de resúmenes para datos cualitativos y Odds ratio.Resultados: predominó el sexo masculino (51,5 %) y las edades 60 y más años (56,9 %); las enfermedades cardiovasculares se presentaron con mayor frecuencia, seguidas de otras enfermedades. El 47,9 % de los pacientes encontró resolutividad en el área y solo el 2,9% falleció. El 88,8 % de los infartados fueron trombolizados y el no serlo no incrementó el riesgo de fallecer.Conclusiones: el área intensiva municipal constituyó un servicio vital para la atención al paciente grave, logrando una resolutividad importante con una disminución de la letalidad dentro del área

Percepción de estudiantes y docentes de la Universidad Autónoma de Bucaramanga (UNAB) sobre el curso en línea de inducción a la modalidad virtual

El presente artículo tiene como objetivo describir y reflexionar sobre la percepción de los estudiantes y docentes del curso en línea: “Inducción a la modalidad virtual”, ofrecido a los nuevos estudiantes de los diferentes programas de UNAB Tecnológica (Colombia). Para ello se realizó un estudio cuantitativo, con un diseño de investigación no experimental transversal que incluyó una muestra de 37 estudiantes y 3 docentes; a quienes se aplicaron diferentes instrumentos de recolección de información diseñados para esta investigación (2 encuestas y 1 guía de análisis del curso). Los resultados indican que la mayoría de estudiantes y docentes encuentran dentro del curso el cumplimiento de aspectos relacionados con los componentes pedagógico, tecnológico y organizativo; y ubican algunos aspectos susceptibles de mejora relacionados con el diseño del curso (componente pedagógico), duración y espacio de tiempo en el que es implementado (componente organizativo) y servicio de consejería (componente tecnológico)

Conservation assessments and Red Listing of the endemic Moroccan flora (monocotyledons)

Morocco constitutes an important centre of plant diversity and speciation in the Mediterranean Basin. However, numerous species are threatened by issues ranging from human activities to global climatic change. In this study, we present the conservation assessments and Red Listing of the endemic Moroccan monocotyledons according to International Union for Conservation of Nature (IUCN) criteria and categories. For each species, we include basic taxonomic information, local names and synonyms, uses, a distribution map, extent of occurrence, area of occupancy, population size and trend, a description of habitats and ecological requirements, and a discussion of the threats affecting the species and habitats. We assessed the threatened status of the endemic Moroccan monocotyledons at the species level (59 species) using the IUCN Red List criteria and categories (Version 3.1). This study shows the high extinction risk to the Moroccan monocotyledon flora, with 95% of threatened species (20% Critically Endangered, 50% Endangered, 25% Vulnerable) and only 5% not threatened (2% Near Threatened and 3% Least Concern). The flora is thus of conservation concern, which is poorly recognized, both nationally and internationally. The study presents the first part and so far the only national IUCN Red Data List for a large group of Moroccan plants, and thus provides an overview of the threatened Moroccan flora. This IUCN Red List is an important first step towards the recognition of the danger to Moroccan biodiversity hotspots, conservation of threatened species and the raising of public awareness at national and international levels