Effect of the spin-orbit interaction on the thermodynamic properties of crystals: The specific heat of bismuth

In recent years, there has been increasing interest in the specific heat $C$ of insulators and semiconductors because of the availability of samples with different isotopic masses and the possibility of performing \textit{ab initio} calculations of its temperature dependence $C(T)$ using as a starting point the electronic band structure. Most of the crystals investigated are elemental (e.g., germanium) or binary (e.g., gallium nitride) semiconductors. The initial electronic calculations were performed in the local density approximation and did not include spin-orbit interaction. Agreement between experimental and calculated results was usually found to be good, except for crystals containing heavy atoms (e.g., PbS) for which discrepancies of the order of 20% existed at the low temperature maximum found for $C/T^3$. It has been conjectured that this discrepancies result from the neglect of spin-orbit interaction which is large for heavy atoms ($\Delta_0\sim$1.3eV for the $p$ valence electrons of atomic lead). Here we discuss measurements and \textit{ab initio} calculations of $C(T)$ for crystalline bismuth ($\Delta_0\sim$1.7 eV), strictly speaking a semimetal but in the temperature region accessible to us ($T >$ 2K) acting as a semiconductor. We extend experimental data available in the literature and notice that the \textit{ab initio} calculations without spin-orbit interaction exhibit a maximum at $\sim$8K, about 20% lower than the measured one. Inclusion of spin-orbit interaction decreases the discrepancy markedly: The maximum of $C(T)$ is now only 7% larger than the measured one. Exact agreement is obtained if the spin-orbit hamiltonian is reduced by a factor of $\sim$0.8.Comment: 4 pages, 3 figure

Influencia del síndrome burnout en el clima organizacional de los gimnasios de entrenamiento funcional del municipio de Cartago Valle del Cauca

El trabajo de investigación planteado fue de tipo descriptivo que utilizo el método cuantitativo correlacional para la recolección de datos, análisis y discusión de resultados, con una población de 50 colaboradores de los gimnasios de entrenamiento funcional del municipio de Cartago Valle, cuyo objetivo principal fue Determinar la influencia del síndrome burnout en el clima organizacional de los mismo, planteando la siguiente hipótesis nula, el síndrome de burnout no afecta al clima organizacional y la hipótesis alternativa, el síndrome de burnout afecta al clima organizacional. Los resultados encontrados muestran que hay una influencia significativa entre el síndrome de burnout y el clima organizacional, puesto que entre más desgaste profesional haya en los entrenadores la percepción de un buen clima disminuirá, además se evidencio que la relación más alta entre las variables de clima organizacional y el síndrome de burnout es empoderamiento, negociación y manejo de conflictos y relaciones

Estudio de los sistemas de puesta a tierra de los edificios de: Medio ambiente, Comunicaciones, Educación, Cafetería Central, Sistemas, y Ciencias Básicas de la Universidad Tecnológica de Pereira

La química del terreno, la cantidad y la calidad de las sales minerales en este pueden influir de modo notable en la resistividad del suelo, por otro lado la humedad y la temperatura afectan la resistividad del terreno, la cual está muy influenciada primordialmente por la humedad y en menor medida no menos importante por su temperatura, son tan significativos estos efectos, que la resistencia del terreno disminuye con el aumento de la humedad y con el incremento de la temperatura. Otro punto que se debe tener en cuenta, es que la varilla o varillas que conforman la puesta a tierra tienden a corroborarse con el tiempo. Considerando lo anterior se desarrolla un estudio de los valores de resistividad y resistencia de las puestas a tierra de algunos edificios de la Universidad Tecnológica de Pereira, para ser comparados con el estudio hecho en el año 2003, en el cual se registraron los valores de resistividad del terreno y de resistencia de las puestas a tierra de los edificios que conforman la Universidad Tecnológica de Pereira, con lo cual se podrá determinar si dichas puestas a tierras a un son eficientes teniendo en cuenta el avance de la Universidad y la evolución del terreno

Applicability Limits of Simplified Human Blockage Models at 5G mm-Wave Frequencies

This paper analyzes the feasibility of using a simple diffraction model to compute the blocking of the human body to millimeter wave radio frequencies in indoor environments. The model makes a set of approximations that are evaluated to determine the applicability limits of such simplified approach, in particular for the human body blockage case. The work presented here: (1) describes briefly the mathematical support that is used to model the concealment using the Knife-Edge model, (2) identifies the potential simplifications applicable to the mathematical model implementation that allow a 3D geometric human body to be modelled with simple 2D shapes, (3) characterizes the polarization influence on the mm-wave blocking for such simplified human body models.This work was supported by the H2020 Marie Curie program, with project grant no: 766231 WAVECOMBEITN-2017Romero-Peña, JS.; Cardona Marcet, N. (2019). Applicability Limits of Simplified Human Blockage Models at 5G mm-Wave Frequencies. IEEE. 1-5. http://hdl.handle.net/10251/1319941

Lattice Properties of PbX (X = S, Se, Te): Experimental Studies and ab initio Calculations Including Spin-Orbit Effects

During the past five years the low temperature heat capacity of simple semiconductors and insulators has received renewed attention. Of particular interest has been its dependence on isotopic masses and the effect of spin- orbit coupling in ab initio calculations. Here we concentrate on the lead chalcogenides PbS, PbSe and PbTe. These materials, with rock salt structure, have different natural isotopes for both cations and anions, a fact that allows a systematic experimental and theoretical study of isotopic effects e.g. on the specific heat. Also, the large spin-orbit splitting of the 6p electrons of Pb and the 5p of Te allows, using a computer code which includes spin-orbit interaction, an investigation of the effect of this interaction on the phonon dispersion relations and the temperature dependence of the specific heat and on the lattice parameter. It is shown that agreement between measurements and calculations significantly improves when spin-orbit interaction is included.Comment: 25 pages, 12 Figures, 1 table, submitted to PR

Vibrational and Thermal Properties of ZnX (X=Se, Te): Density Functional Theory (LDA and GGA) versus Experiment

We calculated the phonon dispersion relations of ZnX (X=Se, Te) employing ab initio techniques. These relations have been used to evaluate the temperature dependence of the respective specific heats of crystals with varied isotopic compositions. These results have been compared with mea- surements performed on crystals down to 2 K. The calculated and measured data are generally in excellent agreement with each other. Trends in the phonon dispersion relations and the correspond- ing densities of states for the zinc chalcogenide series of zincblende-type materials are discussed.Comment: 10 pages, submitted to PR

Aspectos zoonóticos de las especies de fauna silvestre decomisadas por la CAR-DRAM

Este proyecto pretende orientar de manera educativa desde lo ambiental a la población sobre algunos de los conocimientos legales y patológicos, y como, este tipo de aspectos, en lo que se refiere a cada una de las especies descritas en este documento, puede representar algún tipo de afectación a la salud de las personas, teniendo encueta que estos especímenes no son peligrosos para su hábitat, pero, en caso de tomar a la especie animal como doméstico y alterar la zona en la que habita, puede significar un riesgo. Por lo tanto, se debe entender que es una enfermedad zoonótica, “es una enfermedad que puede transmitirse entre animales y seres humanos. “Las enfermedades zoonóticas pueden ser provocadas por virus, bacterias, parásitos y hongos. Algunas de esas enfermedades son muy frecuentes” (Global Health, 2016). Por ello, es importante consolidar un documento que describa algunas características de las especies que son decomisadas por la CAR-DRAM, de tal manera, se evidencie la peligrosidad de tener animales no domésticos como mascotas o en cautiverio. Los animales silvestres llegan a los mercados desde cualquier región y, después de ser capturados, normalmente pasan varias semanas en contacto cercano con personas y otras especies de animales, lo que les proporciona el tiempo suficiente para contagiarse con cualquier agente infeccioso. A esto se le debe añadir el estrés de la captura, el cautiverio, la mala alimentación, el transporte y los cambios de clima a los que se les somete, permitiendo que estos animales comiencen a eliminar agentes que pueden ser patógenos para el humano. (Yarto Jaramillo, 2017). El documento cuenta con (25) veinticinco fichas técnicas que se plantean como una solución para disminuir esta forma de caza y unas posibles causas de salud a raíz de estas tradiciones por parte de la población. Los procesos y trámites que maneja Corporación Autónoma Regional, para incautación o decomiso inmediato a los usuarios sean de una manera más ágil y fácil con un mejor control de la jurisdicción CAR. La base de información estará diseñada por unas fichas técnicas, donde se puede evidenciar las especies que son más frecuentes decomisadas por la CAR-DRAM y sus aspectos patológicos referente en la región y de esta manera tener una herramienta para la población

Urban seismic risk index for Medellín, Colombia, based on probabilistic loss and casualties estimations

The final publication is available at Springer via http://dx.doi.org/10.1007/s11069-015-2056-4Medellín is the second largest city of Colombia with more than 2 million inhabitants according to the latest census and with more than 240,000 public and private buildings. It is located on an intermediate seismic hazard area according to the seismic zonation of Colombia although no destructive earthquakes have occurred having as a consequence low seismic risk awareness among its inhabitants. Using the results of a fully probabilistic risk assessment of the city with a building by building resolution level and considering the dynamic soil response, average annual losses by sectors as well as casualties and other direct effects are obtained and aggregated at county level. Using the holistic evaluation module of the multi-hazard risk assessment CAPRA platform, EvHo, a comprehensive assessment that considered the social fragility and lack or resilience at county level is performed making use of a set of indicators with the objective of capturing the aggravating conditions of the initial physical impact. The urban seismic risk index, USRi, is obtained at county level which is useful to communicate risk to decision-makers and stakeholders besides making easy identifying potential zones that can be problematic in terms of several dimensions of the vulnerability. This case study is an example of how a multidisciplinary research on disaster risk reduction helps to show how risk analysis can be of high relevance for decision-making processes in disaster risk management.Peer ReviewedPostprint (author's final draft

Urban seismic risk index for Medellín, Colombia, based on probabilistic loss and casualties estimations

Medellín is the second largest city of Colombia with more than 2 million inhabitants according to the latest census and with more than 240,000 public and private buildings. It is located on an intermediate seismic hazard area according to the seismic zonation of Colombia although no destructive earthquakes have occurred having as a consequence low seismic risk awareness among its inhabitants. Using the results of a fully probabilistic risk assessment of the city with a building by building resolution level and considering the dynamic soil response, average annual losses by sectors as well as casualties and other direct effects are obtained and aggregated at county level. Using the holistic evaluation module of the multi-hazard risk assessment CAPRA platform, EvHo, a comprehensive assessment that considered the social fragility and lack or resilience at county level is performed making use of a set of indicators with the objective of capturing the aggravating conditions of the initial physical impact. The urban seismic risk index, USRi, is obtained at county level which is useful to communicate risk to decision-makers and stakeholders besides making easy identifying potential zones that can be problematic in terms of several dimensions of the vulnerability. This case study is an example of how a multidisciplinary research on disaster risk reduction helps to show how risk analysis can be of high relevance for decision-making processes in disaster risk management