482 research outputs found
A New Mechanism of Sodium Zirconate Formation
The objective of this study was to synthesize sodium zirconate (Na2ZrO3) from the thermal decomposition of two reactants; sodium acetate (CH3COONa) and Zirconium(IV) acetylacetonate (Zr(C5H7O2)4). The Na2ZrO3 formation mechanism has not been previously reported as it is shown in this work. Also, the reagents are soluble in ethanol; making it possible to apply the mechanism proposed in a spray pyrolysis process. The solid-state reaction was derived from the thermal decomposition of its precursors through the thermogravimetric analysis techniques (TG). The desired product formation was proven by means of an x-ray diffraction technique while the gaseous by-products of the reaction were analyzed using of the IR spectroscopy method (FTIR). Solid-state reaction has three significant weight losses and the TG technique displays these behaviors. The kinetic reaction study was completed using the determination of the activation energy, the pre-exponential factor and the reaction order of such regions. Finally, it was numerically proven that the chemical reaction behavior is well reproduced using the Arrhenius-type kinetic model. Keywords: Sodium zirconate, Arrhenius equation, solid-state reaction, thermal decomposition
A dark energy multiverse
We present cosmic solutions corresponding to universes filled with dark and
phantom energy, all having a negative cosmological constant. All such solutions
contain infinite singularities, successively and equally distributed along
time, which can be either big bang/crunchs or big rips singularities.
Classicaly these solutions can be regarded as associated with multiverse
scenarios, being those corresponding to phantom energy that may describe the
current accelerating universe
Modeling of energy efficiency for residential buildings using artificial neuronal networks
The energy efficiency dataset used to support the findings of this study has been deposited in the GitHub repository https://github.com/mereshow/ann-energy-efficiency.git.[Abstract] Increasing the energy efficiency of buildings is a strategic objective in the European Union, and it is the main reason why numerous studies have been carried out to evaluate and reduce energy consumption in the residential sector. The process of evaluation and qualification of the energy efficiency in existing buildings should contain an analysis of the thermal behavior of the building envelope. To determine this thermal behavior and its representative parameters, we usually have to use destructive auscultation techniques in order to determine the composition of the different layers of the envelope. In this work, we present a nondestructive, fast, and cheap technique based on artificial neural network (ANN) models that predict the energy performance of a house, given some of its characteristics. The models were created using a dataset of buildings of different typologies and uses, located in the northern area of Spain. In this dataset, the models are able to predict the U-opaque value of a building with a correlation coefficient of 0.967 with the real U-opaque measured value for the same building
Permanencia y deserción versus autoeficacia de estudiantes universitarios: Un desafío de la calidad educativa
Introducción. La deserción estudiantil a nivel
universitario sigue siendo un problema vigente que
desencadena pérdidas financieras además de tipo
social y familiar, cuando no se alcanzan las metas de
la formación académica que garantice trabajadores
competentes para el mundo laboral actual. Objetivo.
Analizar la permanencia y deserción versus la
autoeficacia de estudiantes universitarios en el marco
de la calidad educativa. Materiales y métodos. La
población estuvo constituida por los estudiantes
de una universidad de la ciudad de Barranquilla en
Colombia. Se tomó, del registro para el período 2015-
1, una muestra de 322 estudiantes, de los cuales 195
estaban activos y 127 en deserción. El trabajo fue
descriptivo y transaccional de diseño no experimental.
El instrumento de recolección de datos fue la Escala
de Autoeficacia General (EAG), apoyada por el
sistema de información institucional del Departamento
de Admisiones y Registro. Resultados. Se demostró
que no existe una correlación significativa entre
autoeficacia y permanencia, así como tampoco
entre la autoeficacia y la deserción. Sin embargo, un
hallazgo significativo fue demostrar que la media de
autoeficacia en desertores resultó mayor que la de
los estudiantes que permanecieron en la institución.
Conclusiones. Se obtuvo que no se presenta
una correlación significativa entre las variables
autoeficacia, deserción y permanencia.Introdução. A deserção estudantil a nível universitário
segue sendo um problema vigente que desencadeia
perdas financeiras ademais de tipo social e familiar,
quando não se alcançam as metas da formação
acadêmica que garante trabalhadores competentes
para o mundo laboral atual. Objetivo. Analisar a
permanência e deserção versus a auto eficácia de
estudantes universitários no marco da qualidade
educativa. Materiais e métodos. A população foi
constituída pelos estudantes de uma universidade
da cidade de Barranquilla na Colômbia. Se tomou,
do registro para o período 2015-1, uma amostra de
322 estudantes, dos quais 195 estavam ativos e 127
em deserção. O trabalho foi descritivo e transacional
de desenho não experimental. O instrumento de
recolhimento dos dados foi a Escala de Auto eficácia
General (EAG), apoiada pelo sistema de informação
institucional do Departamento de Admissões e
Registro. Resultados. Se demostrou que não existe
uma correlação significativa entre auto eficácia e
permanência, assim como tampouco entre a auto
eficácia e a deserção. Embora, um descobrimento
significativo foi demostrar que a média de auto eficácia
em desertores resultou maior que a dos estudantes que
permaneceram na instituição. Conclusões. Se obteve
que não se apresenta una correlação significativa entre
as variáveis auto eficácia, deserção e permanência.Introduction. the student dropout at university level continues being a current problem that unleashes financial loss besides social and familiar ones, when academic formation goals are not achieved, which assures skillful workers for the current labor world. Objective. To analyze the permanence and dropout versus self-sufficiency of university students in the quality educative framework. Materials and methods. Population was composed by university students in the city of Barranquilla, Colombia. The registry of 2015-1 term, a sample of 322 students, from which 195 were active and 127 on dropout was taken. The work was descriptive and transactional of non-experimental design. Data collection instrument was the General Self-sufficiency scale (GSS), supported by the institutional information system of the Admissions and Registration Department. Results. It was proved that there is not a significant correlation between self-efficiency and permanence, as neither between self-sufficiency or dropout; however, a significant finding was to prove that the average of dropout's self-sufficient students resulted greater than the one of students staying in the institution. Conclusions. It was obtained that there is not a significant correlation among self-efficiency, dropout, and permanence variables
Permanencia y deserción versus autoeficacia de estudiantes universitarios: Un desafío de la calidad educativa
Introduction. the student dropout at university level continues being a current problem that unleashes financial loss besides social and familiar ones, when academic formation goals are not achieved, which assures skillful workers for the current labor world. Objective. To analyze the permanence and dropout versus self-sufficiency of university students in the quality educative framework. Materials and methods. Population was composed by university students in the city of Barranquilla, Colombia. The registry of 2015-1 term, a sample of 322 students, from which 195 were active and 127 on dropout was taken. The work was descriptive and transactional of non-experimental design. Data collection instrument was the General Self-sufficiency scale (GSS), supported by the institutional information system of the Admissions and Registration Department. Results. It was proved that there is not a significant correlation between self-efficiency and permanence, as neither between self-sufficiency or dropout; however, a significant finding was to prove that the average of dropout's self-sufficient students resulted greater than the one of students staying in the institution. Conclusions. It was obtained that there is not a significant correlation among self-efficiency, dropout, and permanence variables.Introducción. La deserción estudiantil a nivel
universitario sigue siendo un problema vigente que
desencadena pérdidas financieras además de tipo
social y familiar, cuando no se alcanzan las metas de
la formación académica que garantice trabajadores
competentes para el mundo laboral actual. Objetivo.
Analizar la permanencia y deserción versus la
autoeficacia de estudiantes universitarios en el marco
de la calidad educativa. Materiales y métodos. La
población estuvo constituida por los estudiantes
de una universidad de la ciudad de Barranquilla en
Colombia. Se tomó, del registro para el período 2015-
1, una muestra de 322 estudiantes, de los cuales 195
estaban activos y 127 en deserción. El trabajo fue
descriptivo y transaccional de diseño no experimental.
El instrumento de recolección de datos fue la Escala
de Autoeficacia General (EAG), apoyada por el
sistema de información institucional del Departamento
de Admisiones y Registro. Resultados. Se demostró
que no existe una correlación significativa entre
autoeficacia y permanencia, así como tampoco
entre la autoeficacia y la deserción. Sin embargo, un
hallazgo significativo fue demostrar que la media de
autoeficacia en desertores resultó mayor que la de
los estudiantes que permanecieron en la institución.
Conclusiones. Se obtuvo que no se presenta
una correlación significativa entre las variables
autoeficacia, deserción y permanencia.Introdução. A deserção estudantil a nível universitário
segue sendo um problema vigente que desencadeia
perdas financeiras ademais de tipo social e familiar,
quando não se alcançam as metas da formação
acadêmica que garante trabalhadores competentes
para o mundo laboral atual. Objetivo. Analisar a
permanência e deserção versus a auto eficácia de
estudantes universitários no marco da qualidade
educativa. Materiais e métodos. A população foi
constituída pelos estudantes de uma universidade
da cidade de Barranquilla na Colômbia. Se tomou,
do registro para o período 2015-1, uma amostra de
322 estudantes, dos quais 195 estavam ativos e 127
em deserção. O trabalho foi descritivo e transacional
de desenho não experimental. O instrumento de
recolhimento dos dados foi a Escala de Auto eficácia
General (EAG), apoiada pelo sistema de informação
institucional do Departamento de Admissões e
Registro. Resultados. Se demostrou que não existe
uma correlação significativa entre auto eficácia e
permanência, assim como tampouco entre a auto
eficácia e a deserção. Embora, um descobrimento
significativo foi demostrar que a média de auto eficácia
em desertores resultou maior que a dos estudantes que
permaneceram na instituição. Conclusões. Se obteve
que não se apresenta una correlação significativa entre
as variáveis auto eficácia, deserção e permanência
A Fungal Effector With Host Nuclear Localization and DNA-Binding Properties Is Required for Maize Anthracnose Development
Plant pathogens have the capacity to manipulate the host immune system through the secretion of effectors. We identified 27 putative effector proteins encoded in the genome of the maize anthracnose pathogen Colletotrichum graminicola that are likely to target the host’s nucleus, as they simultaneously contain sequence signatures for secretion and nuclear localization. We functionally characterized one protein, identified as CgEP1. This protein is synthesized during the early stages of disease development and is necessary for anthracnose development in maize leaves, stems, and roots. Genetic, molecular, and biochemical studies confirmed that this effector targets the host’s nucleus and defines a novel class of double-stranded DNA-binding protein. We show that CgEP1 arose from a gene duplication in an ancestor of a lineage of monocot-infecting Colletotrichum spp. and has undergone an intense evolution process, with evidence for episodes of positive selection. We detected CgEP1 homologs in several species of a grass-infecting lineage of Colletotrichum spp., suggesting that its function may be conserved across a large number of anthracnose pathogens. Our results demonstrate that effectors targeted to the host nucleus may be key elements for disease development and aid in the understanding of the genetic basis of anthracnose development in maize plants.Fil: Vargas, Walter Alberto. Universidad de Salamanca; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sanz Martín, José M.. Universidad de Salamanca; EspañaFil: Rech, Gabriel E.. Universidad de Salamanca; EspañaFil: Armijos Jaramillo, Vinicio D.. Universidad de Salamanca; EspañaFil: Rivera Rodriguez, Lina Patricia. Universidad de Salamanca; EspañaFil: Echeverria, María de Las Mercedes. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Díaz Mínguez, José M.. Universidad de Salamanca; EspañaFil: Thon, Michael R.. Universidad de Salamanca; EspañaFil: Sukno, Serenella A.. Universidad de Salamanca; Españ
The macrofauna associated to the bamboo coral Isidella elongata: to what extent the impact on isideidae affects diversification of deep-sea fauna
Macrofauna associated with the bamboo coral Isidella elongata was analysed in the Balearic Basin at depths of 697–1308 m. The diversity of associated macrofauna and the specific associations identified depended on different morphological characteristics of colonies, such as height or density of rami. Species associated with Isidella consisted mainly of sessile fauna, such as cnidarians (the actinian Amphianthus dornhii and the solitary coral Desmophyllum dianthus) and cirripeds (Gibossaverruca sp.). The strongest relationship (commensalism) occurred for the Pontogeneiidae amphipod Dautzenbergia megacheir, living attached to colonies of Isidella and represented by all population stages from adult (oostegal) females and males to juveniles. Species-coral relationships between Dautzenbergia and bamboo corals (Isididae) are plausible. Dautzenbergia spp. showed morphological differences between Atlantic (described by Walker 1897 as “eyes wanting”) and Mediterranean (with well-developed reddish eyes) specimens. This would suggest diversification of this genus, as has been recently suggested for Pleustidae associated with deep gorgonians. The diversity of the macrofaunal community associated with I. elongata was higher in the most mature (larger colonies with higher density) fields found NW of Mallorca, with higher colonies than in other parts of the Mediterranean. This was the only site where Gibossaverruca sp. (a first Mediterranean faunal record) and D. dianthus were collected. These complex associations between macrofauna and deep-water corals may provide arguments to protect these fragile ecosystems as a source of faunal diversity and diversification.Versión del editor3,87
Quantum cosmic models and thermodynamics
The current accelerating phase of the evolution of the universe is considered
by constructing most economical cosmic models that use just general relativity
and some dominating quantum effects associated with the probabilistic
description of quantum physics. Two of such models are explicitly analyzed.
They are based on the existence of a sub-quantum potential and correspond to a
generalization of the spatially flat exponential model of de Sitter space. The
thermodynamics of these two cosmic solutions is discussed, using the second
principle as a guide to choose which among the two is more feasible. The paper
also discusses the relativistic physics on which the models are based, their
holographic description, some implications from the classical energy
conditions, and an interpretation of dark energy in terms of the entangled
energy of the universe.Comment: 15 pages, 1 figure, accepted for publication in Class. Quantum Gra
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