Crystallographic point group symmetry (CPGS) such as polar and nonpolar crystal classes have long... more Crystallographic point group symmetry (CPGS) such as polar and nonpolar crystal classes have long been known to classify compounds that have spin-orbit-induced spin splitting. While taking a journey through the Brillouin zone (BZ) from one k-point to another for a fixed CPGS, it is expected that the wave vector point group symmetry (WPGS) can change, and consequently, a qualitative change in the texture of the spin polarization can occur [the expectation value of spin operator S nk 0 in Bloch state u(n, k) and the wave vector k 0 ]. However, the nature of the spin texture (ST) change is generally unsuspected. In this paper, we determine a full classification of the linear-ink ST patterns based on the polarity and chirality reflected in the WPGS at k 0. The spin-polarization vector S nk 0 controlling the ST is bound to be parallel to the rotation axis and perpendicular to the mirror planes, and hence, symmetry operation types in WPGSs impose symmetry restriction to the ST. For instance, the ST is always parallel to the wave vector k in nonpolar chiral WPGSs since they contain only rotational symmetries. Some consequences of the ST classification based on the symmetry operations in the WPGS include the observation of ST patterns that are unexpected according to the symmetry of the crystal. For example, it is usually established that spin-momentum locking effect (spin vector always perpendicular to the wave vector) requires the crystal inversion symmetry breaking by an asymmetric electric potential. However, we find that polar WPGS can have this effect even in compounds without electric dipoles or external electric fields. We use the determined relation between WPGS and ST as a design principle to select compounds with multiple STs near band edges at different k valleys. Based on high-throughput calculations for 1481 compounds, we find 37 previously fabricated materials with different STs near band edges. The ST classification as well as the predicted compounds with multiple STs can be a platform for potential application for spin-valleytronics and the control of the ST by accessing different valleys.
Three-dimensional topological insulators protected by both the time reversal (TR) and mirror symm... more Three-dimensional topological insulators protected by both the time reversal (TR) and mirror symmetries were recently predicted and observed. Two-dimensional materials featuring this property and their potential for device applications have been less explored. We find that in these systems, the spin-polarization of edge states can be controlled with an external electric field breaking the mirror symmetry. This symmetry requires that the spin-polarization is perpendicular to the mirror plane, therefore, the electric field induces spin-polarization components parallel to the mirror plane. Since this field preserves the TR topological protection, we propose a transistor model using the spindirection of protected edge states as a switch. In order to illustrate the generality of the proposed phenomena, we consider compounds protected by mirror planes parallel and perpendicular to the structure, e.g., Na3Bi and half-functionalized (HF) hexagonal compounds, respectively. For this purpose, we first construct a tight-binding effective model for the Na3Bi compound and predict that HF-honeycomb lattice materials are also dual topological insulators.
We put forward a tight-binding model for rhombohedral topological insulators materials with the s... more We put forward a tight-binding model for rhombohedral topological insulators materials with the space group D 5 3d (R3m). The model describes the bulk band structure of these materials over the whole Brillouin zone. Within this framework, we also describe the topological nature of surface states, characterized by a Dirac cone-like dispersion and the emergence of surface projected bulk states near to the Dirac-point in energy. We find that the breaking of the R3 symmetry as one moves away from the Γ point has an important role in the hybridization of the px, py, and pz atomic orbitals. In our tight-binding model, the latter leads to a band mixing matrix element ruled by a single parameter. We show that our model gives a good description of the strategies/mechanisms proposed in the literature to eliminate and/or energy shift the bulk states away from the Dirac point, such as stacking faults and the introduction of an external applied electric field.
Entomotropica Revista Internacional Para El Estudio De La Entomologia Tropical, Mar 7, 2008
Glycaspis brimblecombei Moore (Hemiptera:Psyllidae). Red Gum Lerp . Nueva plaga forestal en Venez... more Glycaspis brimblecombei Moore (Hemiptera:Psyllidae). Red Gum Lerp . Nueva plaga forestal en Venezuela.
La justicia transicional debe enfrentar la negación de las atrocidades. A pesar de la sofisticaci... more La justicia transicional debe enfrentar la negación de las atrocidades. A pesar de la sofisticación del marco de derechos humanos presente en el sistema legal colombiano, el campo de la justicia transicional en Colombia adolece de un significativo grado de indeterminación normativa, como si dicho campo aconteciera en un "vacío constitucional". Como consecuencia, ha sido objeto de uso estratégico por parte de distintos actores políticos dotados de intencionalidad en la fijación del sentido del arreglo institucional de la llamada justicia transicional.
El archivo científico del paleontólogo catalán Miquel Crusafont i Pairó, depositado en l'Institut... more El archivo científico del paleontólogo catalán Miquel Crusafont i Pairó, depositado en l'Institut Català de Paleontologia en Sabadell, contiene un valioso material documental que permite conocer y comprender el desarrollo de la paleontología de vertebrados y de la paleoantropología de Cataluña y Europa. La clasificación de estos documentos y el interés personal y científico de los autores ha permitido identificar uno de esos casos en que el patrocinio y el mecenazgo impulsan una actividad paleontológica que no siempre produce resultados en consonancia con la inversión, pero que sienta las bases de desarrollos futuros. Se trata del caso del yacimiento de Can Llobateres (Sabadell), su excavación y protección durante los años 60 gracias al apoyo del paleontólogo Jean Hürzeler, la empresa Sandoz y la Wenner Gren Foundation, una historia que ha continuado hasta la actualidad. Este caso sirve de lente de aumento para historias paralelas, generales, particulares y personales.
ABSTRACT A successful multi-agent system requires the intelligent agents to perform within a dyna... more ABSTRACT A successful multi-agent system requires the intelligent agents to perform within a dynamically complex environment where proper and quick response in a cooperative manner is a primary key to successfully complete a task. This paper proposes a nondeterministic decision making method using electric fields and high-level decision making. Different layers are designed, defined, and implemented for the software architecture with focus on system adaptability, sustainability, and optimization. The proposed decision making approach in this paper is based on layered artificial intelligence implemented using vector-based fuzzy electric fields and a decision tree. Furthermore, an approach to model the world which is, in this paper, called Agent Relative Polar Localization is introduced. This world model is based on fuzzy measurements and polar coordinates. In order to optimize the overall performance of the system learning methods have been introduced to the system. The proposed system in this paper has been implemented on soccer robots to evaluate the performance of the system. The results show that the proposed system implemented on the soccer robots is reliable and robust.
Esta region esta constituida por una serie de grabens y horsts dirigidos SW-NE y por algunos hors... more Esta region esta constituida por una serie de grabens y horsts dirigidos SW-NE y por algunos horsts transversales. Los primeros, numerados de Occidente a Oriente, son los siguientes:
n el ámbito académico, en particular el relacionado con la temática de las organizaciones sociale... more n el ámbito académico, en particular el relacionado con la temática de las organizaciones sociales centradas en la producción, es muy fácil encontrar literatura sobre el tema del cambio. Se habla sobre sus consecuencias, sus causas y mucho sobre los mejores procedimientos para llevarlo a cabo. No obstante, es tangencial la atención al concepto propiamente dicho del cambio organizacional. Se habla de cambio en las empresas pero poco se precisa sobre las dimensiones: del qué, el por qué, el cómo transcurren internamente los cambios. Las propuestas más frecuentes se focalizan en el para qué y en el cómo lograrlo. En tal sentido, aquí se explora el qué es lo que cambia en las organizaciones
Crystallographic point group symmetry (CPGS) such as polar and nonpolar crystal classes have long... more Crystallographic point group symmetry (CPGS) such as polar and nonpolar crystal classes have long been known to classify compounds that have spin-orbit-induced spin splitting. While taking a journey through the Brillouin zone (BZ) from one k-point to another for a fixed CPGS, it is expected that the wave vector point group symmetry (WPGS) can change, and consequently, a qualitative change in the texture of the spin polarization can occur [the expectation value of spin operator S nk 0 in Bloch state u(n, k) and the wave vector k 0 ]. However, the nature of the spin texture (ST) change is generally unsuspected. In this paper, we determine a full classification of the linear-ink ST patterns based on the polarity and chirality reflected in the WPGS at k 0. The spin-polarization vector S nk 0 controlling the ST is bound to be parallel to the rotation axis and perpendicular to the mirror planes, and hence, symmetry operation types in WPGSs impose symmetry restriction to the ST. For instance, the ST is always parallel to the wave vector k in nonpolar chiral WPGSs since they contain only rotational symmetries. Some consequences of the ST classification based on the symmetry operations in the WPGS include the observation of ST patterns that are unexpected according to the symmetry of the crystal. For example, it is usually established that spin-momentum locking effect (spin vector always perpendicular to the wave vector) requires the crystal inversion symmetry breaking by an asymmetric electric potential. However, we find that polar WPGS can have this effect even in compounds without electric dipoles or external electric fields. We use the determined relation between WPGS and ST as a design principle to select compounds with multiple STs near band edges at different k valleys. Based on high-throughput calculations for 1481 compounds, we find 37 previously fabricated materials with different STs near band edges. The ST classification as well as the predicted compounds with multiple STs can be a platform for potential application for spin-valleytronics and the control of the ST by accessing different valleys.
Three-dimensional topological insulators protected by both the time reversal (TR) and mirror symm... more Three-dimensional topological insulators protected by both the time reversal (TR) and mirror symmetries were recently predicted and observed. Two-dimensional materials featuring this property and their potential for device applications have been less explored. We find that in these systems, the spin-polarization of edge states can be controlled with an external electric field breaking the mirror symmetry. This symmetry requires that the spin-polarization is perpendicular to the mirror plane, therefore, the electric field induces spin-polarization components parallel to the mirror plane. Since this field preserves the TR topological protection, we propose a transistor model using the spindirection of protected edge states as a switch. In order to illustrate the generality of the proposed phenomena, we consider compounds protected by mirror planes parallel and perpendicular to the structure, e.g., Na3Bi and half-functionalized (HF) hexagonal compounds, respectively. For this purpose, we first construct a tight-binding effective model for the Na3Bi compound and predict that HF-honeycomb lattice materials are also dual topological insulators.
We put forward a tight-binding model for rhombohedral topological insulators materials with the s... more We put forward a tight-binding model for rhombohedral topological insulators materials with the space group D 5 3d (R3m). The model describes the bulk band structure of these materials over the whole Brillouin zone. Within this framework, we also describe the topological nature of surface states, characterized by a Dirac cone-like dispersion and the emergence of surface projected bulk states near to the Dirac-point in energy. We find that the breaking of the R3 symmetry as one moves away from the Γ point has an important role in the hybridization of the px, py, and pz atomic orbitals. In our tight-binding model, the latter leads to a band mixing matrix element ruled by a single parameter. We show that our model gives a good description of the strategies/mechanisms proposed in the literature to eliminate and/or energy shift the bulk states away from the Dirac point, such as stacking faults and the introduction of an external applied electric field.
Entomotropica Revista Internacional Para El Estudio De La Entomologia Tropical, Mar 7, 2008
Glycaspis brimblecombei Moore (Hemiptera:Psyllidae). Red Gum Lerp . Nueva plaga forestal en Venez... more Glycaspis brimblecombei Moore (Hemiptera:Psyllidae). Red Gum Lerp . Nueva plaga forestal en Venezuela.
La justicia transicional debe enfrentar la negación de las atrocidades. A pesar de la sofisticaci... more La justicia transicional debe enfrentar la negación de las atrocidades. A pesar de la sofisticación del marco de derechos humanos presente en el sistema legal colombiano, el campo de la justicia transicional en Colombia adolece de un significativo grado de indeterminación normativa, como si dicho campo aconteciera en un "vacío constitucional". Como consecuencia, ha sido objeto de uso estratégico por parte de distintos actores políticos dotados de intencionalidad en la fijación del sentido del arreglo institucional de la llamada justicia transicional.
El archivo científico del paleontólogo catalán Miquel Crusafont i Pairó, depositado en l'Institut... more El archivo científico del paleontólogo catalán Miquel Crusafont i Pairó, depositado en l'Institut Català de Paleontologia en Sabadell, contiene un valioso material documental que permite conocer y comprender el desarrollo de la paleontología de vertebrados y de la paleoantropología de Cataluña y Europa. La clasificación de estos documentos y el interés personal y científico de los autores ha permitido identificar uno de esos casos en que el patrocinio y el mecenazgo impulsan una actividad paleontológica que no siempre produce resultados en consonancia con la inversión, pero que sienta las bases de desarrollos futuros. Se trata del caso del yacimiento de Can Llobateres (Sabadell), su excavación y protección durante los años 60 gracias al apoyo del paleontólogo Jean Hürzeler, la empresa Sandoz y la Wenner Gren Foundation, una historia que ha continuado hasta la actualidad. Este caso sirve de lente de aumento para historias paralelas, generales, particulares y personales.
ABSTRACT A successful multi-agent system requires the intelligent agents to perform within a dyna... more ABSTRACT A successful multi-agent system requires the intelligent agents to perform within a dynamically complex environment where proper and quick response in a cooperative manner is a primary key to successfully complete a task. This paper proposes a nondeterministic decision making method using electric fields and high-level decision making. Different layers are designed, defined, and implemented for the software architecture with focus on system adaptability, sustainability, and optimization. The proposed decision making approach in this paper is based on layered artificial intelligence implemented using vector-based fuzzy electric fields and a decision tree. Furthermore, an approach to model the world which is, in this paper, called Agent Relative Polar Localization is introduced. This world model is based on fuzzy measurements and polar coordinates. In order to optimize the overall performance of the system learning methods have been introduced to the system. The proposed system in this paper has been implemented on soccer robots to evaluate the performance of the system. The results show that the proposed system implemented on the soccer robots is reliable and robust.
Esta region esta constituida por una serie de grabens y horsts dirigidos SW-NE y por algunos hors... more Esta region esta constituida por una serie de grabens y horsts dirigidos SW-NE y por algunos horsts transversales. Los primeros, numerados de Occidente a Oriente, son los siguientes:
n el ámbito académico, en particular el relacionado con la temática de las organizaciones sociale... more n el ámbito académico, en particular el relacionado con la temática de las organizaciones sociales centradas en la producción, es muy fácil encontrar literatura sobre el tema del cambio. Se habla sobre sus consecuencias, sus causas y mucho sobre los mejores procedimientos para llevarlo a cabo. No obstante, es tangencial la atención al concepto propiamente dicho del cambio organizacional. Se habla de cambio en las empresas pero poco se precisa sobre las dimensiones: del qué, el por qué, el cómo transcurren internamente los cambios. Las propuestas más frecuentes se focalizan en el para qué y en el cómo lograrlo. En tal sentido, aquí se explora el qué es lo que cambia en las organizaciones
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