Electron pairing: from metastable electron pair to bipolaron

Starting from the shell structure in atoms and the significant correlation within electron pairs, we distinguish the exchange-correlation effects between two electrons of opposite spins occupying the same orbital from the average correlation among many electrons in a crystal. In the periodic potential of the crystal with lattice constant larger than the effective Bohr radius of the valence electrons, these correlated electron pairs can form a metastable energy band above the corresponding single-electron band separated by an energy gap. In order to determine if these metastable electron pairs can be stabilized, we calculate the many-electron exchange-correlation renormalization and the polaron correction to the two-band system with single electrons and electron pairs. We find that the electron-phonon interaction is essential to counterbalance the Coulomb repulsion and to stabilize the electron pairs. The interplay of the electron-electron and electron-phonon interactions, manifested in the exchange-correlation energies, polaron effects, and screening, is responsible for the formation of electron pairs (bipolarons) that are located on the Fermi surface of the single-electron band.Comment: 17 pages, 6 figures, Journal of Physics Communications 201

Burnout syndrome prevalence in veterinarians working in Chile

Burnout Syndrome is a psycho-emotional syndrome that affects workers in any activity or profession. In recent years, veterinarians have been described as one of the most affected professionals, which has motivated the development of this research. The primary objective of this work was to determine the prevalence of Burnout Syndrome in veterinarians working in Chile. We evaluated the possible correlation of Burnout Syndrome with socio-demographic variables. The Socio-Demographic Characterization Survey and the Maslach Burnout Syndrome Inventory-General Survey (MBI) were applied to 521 participants, who were contacted through the Veterinary Medical Association of Chile (COLMEVET) and social networks. Fisher and Chi-square statistical tests and correspondence analysis were used to determine the association among variables. The prevalence of Burnout Syndrome in Chilean veterinarians was 24% (124/521). There was statistical significance between Burnout Syndrome and the variables ‘years in employment’ and ‘monthly salary’. There is a high prevalence of Burnout Syndrome in veterinarians working in Chile that was related to the variables ‘years in employment’ and ‘monthly salary’. Prevention using psychological therapy could reduce the incidence of symptoms linked to adaptive difficulties, cognitive discrepancies, psychological discomfort, and emotional regulation, promoting health improvement and resistance to Burnout Syndrome in Chilean veterinarians. This research corresponds to the first exploratory study related to the subject in Chil

An overview of memory: some issues on structures and organization in the legal domain

Lawyers often need to look for previous similar legal cases when analysing new ones. The more previous cases, the more time is spent. Classical search engines execute termbased retrieval, which may miss relevant documents as well as fetch several irrelevant ones, causing lack of useful information and waste of time. Ideally, retrieval should be meaning-based. Humans beings are able to do e cient searches due to their knowledge. Therefore, semantic search requires knowledge. This paper presents a semantic search engine. Along the paper, several issues concerning specially knowledge representation and memory are discussed. A formalism based on models of comprehension is introduced, as well as its motivation. Examples of representation of sentences in natural language from the Legal Domain are provided. The search engine and its architecture, based on domain knowledge, are brie y commented. The main goal is to give legal o ces the opportunity to save time by providing a more suitable document retrieval.Eje: Agentes y Sistemas Inteligentes (ASI)Red de Universidades con Carreras en Informática (RedUNCI

An overview of memory: some issues on structures and organization in the legal domain

Lawyers often need to look for previous similar legal cases when analysing new ones. The more previous cases, the more time is spent. Classical search engines execute termbased retrieval, which may miss relevant documents as well as fetch several irrelevant ones, causing lack of useful information and waste of time. Ideally, retrieval should be meaning-based. Humans beings are able to do e cient searches due to their knowledge. Therefore, semantic search requires knowledge. This paper presents a semantic search engine. Along the paper, several issues concerning specially knowledge representation and memory are discussed. A formalism based on models of comprehension is introduced, as well as its motivation. Examples of representation of sentences in natural language from the Legal Domain are provided. The search engine and its architecture, based on domain knowledge, are brie y commented. The main goal is to give legal o ces the opportunity to save time by providing a more suitable document retrieval.Eje: Agentes y Sistemas Inteligentes (ASI)Red de Universidades con Carreras en Informática (RedUNCI

Query expansion and noise treatment for information retrieval

Most of the search engines available over the Web are based on mathematical approaches | classical techniques in the Information Retrieval area. Thereby, they are suitable for the retrieval of documents containing some or all the terms of a query, though not to retrieve the documents containing the meaning those terms were intended to express. This paper presents some advantages obtained from query expansion with WordNet and noise treatment with knowledge on top of Paraconsistent Logic. Both methods are semantically driven, allowing the retrieval of documents which do not contain any term of the original query. Noise treatment results from the combination of a smooth term comparison with knowledge about term authentication based on behaviors of features in the collection. Although query expansion recurs for every query, noise treatment is part of the indexing mechanism, causing no overhead in queries. The domain is retrieval of ontologies represented in Resource Description Framework.Eje: Agentes y Sistemas Inteligentes (ASI)Red de Universidades con Carreras en Informática (RedUNCI

Nematodos en Suelos Cultivados con Cafeto (Coffea arábica L.) en el Distrito de Marinca (Zona Comprendida entre los 600 a 1200 m. s.n.m.)

El presente trabajo de investigación se realizó en el distrito de Marinca, Sierra Nevada de Santa Marta y comprendió las veredas de Marinca, Mundo nuevo y parte norte de la vereda Oriente, Municipio de Santa Marta, Departamento del Magdalena, con rangos de alturas de 600 a 1200 m.s.n.m. De las 107 fincas existentes en la región se escogieron 48 fincas que están comprendidas en un rango de 10 a 200 hectáreas. De estas 48 fincas se sacó el 30%, que es igual a 15 fincas, las cuales se seleccionaron por el sistema de muestras al azar sistemáticas. o se realizó en dos partes: A: Trabajo de Campo. En esta etapa se tomaron las muestras de suelo de aproximadamente un (1) kilogramo, estas se echaron en una bolsa plástica con su respectiva identificación, colocándola en una caja de icopor con hielo, para conservarlas durante el transporte al laboratorio. B: Trabajo de Laboratorio. En esta fase se procesaron las muestras, se contaron los nematodos, se pescaron e identificaron los géneros de ellos presentes en cada una de las muestras. Para la extracción de los géneros de nematodos, se usó el método tamizado embudo de Bareman modificado. Las mallas de los tamices utilizados eran de 0.063mm, 0.01 mm, 0.25 mm, y 1.00 mm, colocados de mayor a menor, tomando los residuos de los dos últimos tamices y haciendo extracción total a las 72' horas, seguidamente se hizo la fijación del nematodo. Al hacer la identificación de los nematodos, se encontraron doce géneros de nematodos fitopatógenos: Xiphinema spp, Paratylenchus sp, Aphelenchus sp, Helicotylenchus sp, Pratylenchus sp, phelenchoides sp, Tylenchus sp, TrIchodorus sp, Criconemella sp, Ditylenchus sp, Boleodorus sp, Macrophosthonia sp y varios géneros de no fitopatógenos. Los porcentajes de ocurrencia de los nemátodos encontrados fueron: Xiphinema spp 56.28%, Paratylenchus sp 4.07%, Aphelenchus sp 3.64%, Pratylenchus sp 3.01%, Helicotylenchus sp 2.36%, Aphelenchoides sp 2.12%, Tylenchus sp 2.04%, Trichodorus sp 0.04%; Ditylenchus sp 0.05%, Criconemella sp 0.03%, Macrophosthia sp 0.03%. Boleodorus sp 0.02% y no fitopatógenos 26,22%. Se hizo el análisis químico de los suelos de cada una de las muestras (pH, Nitrógeno, Fosforo, Potasio y Textura) y se observó que no hay relación alguna con las poblaciones y porcentajes de ocurrencia de los nematodo

An overview of memory: some issues on structures and organization in the legal domain

Lawyers often need to look for previous similar legal cases when analysing new ones. The more previous cases, the more time is spent. Classical search engines execute termbased retrieval, which may miss relevant documents as well as fetch several irrelevant ones, causing lack of useful information and waste of time. Ideally, retrieval should be meaning-based. Humans beings are able to do e cient searches due to their knowledge. Therefore, semantic search requires knowledge. This paper presents a semantic search engine. Along the paper, several issues concerning specially knowledge representation and memory are discussed. A formalism based on models of comprehension is introduced, as well as its motivation. Examples of representation of sentences in natural language from the Legal Domain are provided. The search engine and its architecture, based on domain knowledge, are brie y commented. The main goal is to give legal o ces the opportunity to save time by providing a more suitable document retrieval.Eje: Agentes y Sistemas Inteligentes (ASI)Red de Universidades con Carreras en Informática (RedUNCI