Papers by Hector John Silva
Physical Review B
We provide a natural generalization of a Riemannian structure, i.e., a metric, recently introduce... more We provide a natural generalization of a Riemannian structure, i.e., a metric, recently introduced by Sjöqvist [1] for the space of non degenerate density matrices, to the degenerate case, i.e., in which the eigenspaces have dimension greater or equal to one. We present a physical interpretation of the metric in terms of an interferometric measurement. We study this metric, physically interpreted as an interferometric susceptibility, to the study of topological phase transitions at finite temperatures for band insulators. We compare the behaviors of this susceptibility and the one coming from the well-known Bures metric, showing them to be dramatically different. While both infer zero temperature phase transitions, only the former predicts finite temperature phase transitions as well. The difference in behaviours can be traced back to a symmetry breaking mechanism, akin to Landau-Ginzburg theory, by which the Uhlmann gauge group is broken down to a subgroup determined by the type of sytem's density matrix (i.e., the ranks of its spectral projectors).
Conceiving creative behavior as generation of novel criteria that give rise to different continge... more Conceiving creative behavior as generation of novel criteria that give rise to different contingencies (Carpio, 1999; 2005), the effects of two levels of variability in the conditions of training were compared on the effective performance in transference tests and on the generation of matching criteria. 20 university students randomly assigned to 4 experimental groups that distinguished themselves by the level of variability in the problems to solve participated. The results indicate that the variability significantly affects the execution in transference tests and facilitates the generation of matching criteria. Finally, the possibilities that experimental analysis has on the study of creative behavior are discussed.
Suma Psicológica, 2010
En este estudio se evaluan los efectos de variar el tipo de criterio y el tipo de morfologia del ... more En este estudio se evaluan los efectos de variar el tipo de criterio y el tipo de morfologia del hacer estudiantil sobre el porcentaje de respuestas correctas en tareas de ajuste lector. Participaron 20 estudiantes universitarios asignados a uno de cuatro grupos que se distinguian por la constancia - variabilidad del criterio y la constancia - variabilidad de la morfologia de la respuesta para satisfacer el criterio.Se aplico una evaluacion inicial a todos los participantes, un entrenamiento y una evaluacion final, semejante a la primera. Se encontro que, en general, el entrenamiento variable de criterios y morfologia tuvo mayores efectos positivos sobre el desempeno en la segunda evaluacion, en contraste con los grupos expuestos a un solo criterio o a una sola morfologia. Los resultados permiten discutir el papel de la morfologia como estrategia de aprendizaje efectiva al margen del criterio funcional, del dominio y del texto leido.
Revista Mexicana de Biodiversidad, 2011
The primary lowland rainforest around the Mayan ruins of Palenque, in the state of Chiapas, Mexic... more The primary lowland rainforest around the Mayan ruins of Palenque, in the state of Chiapas, Mexico, has been the focus of much study. The second growth and the mosaic of pasture and farmland surrounding the protected area of Palenque National Park also have received some attention by researchers and visitors. Until now though, a complete avifaunal list for this area had not been compiled. In our judgment, 353 species have been recorded reliably, a hundred more than previously reported. An additional 27 species have been reported at the site on multiple occasions but for which we feel there is no definitive evidence. There are 202 regular breeders, most of them resident, and 87 migrants that winter or pass through regularly. Relative capture rates for understorey birds indicate that Phaethornis longirostris and Henicorhina leucosticta are most often caught, and some rarely seen birds, such a Geotrygon montana, are less rare than previously thought. In a state in which habitat destruction is routine, in which national parks are increasingly becoming forested islands, we need baseline data such as these to get a clearer idea of what occurs there if we are to understand anthropogenic effects on forests.
Journal of Behavior, Health & Social Issues, 2010
Se sostiene que los “enigmas” que hasta hoy rodean al concepto “pensamiento” son producto de una ... more Se sostiene que los “enigmas” que hasta hoy rodean al concepto “pensamiento” son producto de una profunda incomprensión conceptual derivada de no distinguir entre preguntas filosóficas y problemas científicos. Se señala que tal incomprensión tiene lugar al no reconocer la naturaleza multívoca y contextual de los términos en el lenguaje ordinario vs. la naturaleza abstracta y precisa de los términos en ciencia. Se argumenta que dadas tales diferencias, el concepto “pensamiento”, y conceptos relacionados, no pueden ser abordados directamente como objeto de estudio en psicología, al menos que, tales conceptos se acoten en conexión con un sistema teórico y con la terminología apropiada. Se señala que una de las vías para elucidar la incomprensión citada, es la identificación de los referentes empíricos de las expresiones a partir del análisis de los usos de los términos. En este contexto, se analiza el uso de las expresiones “pensamiento” y “pensamiento crítico”, se identifican sus refe...
Universitas Psychologica, 2007
How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative
Acta Colombiana De Psicologia, Dec 1, 2008
Se evaluaron los efectos de distintos tipos funcionales de contactos previos con los referentes d... more Se evaluaron los efectos de distintos tipos funcionales de contactos previos con los referentes de un texto (historia de referencialidad e historia situacional efectiva) sobre la ejecución de estudiantes universitarios en una prueba de ajuste lector. Participaron cinco grupos experimentales diferenciados por el tipo de historia de contacto construida mediante un entrenamiento. Cada tipo de historia era progresivamente más complejo: Contextual, Suplementario, Selector, Sustitutivo Referencial y Sustitutivo No Referencial Un sexto grupo (control) no tuvo ningún entrenamiento. Los seis grupos fueron posteriormente expuestos a la prueba de ajuste lector, consistente en preguntas de diferente complejidad funcional. Los resultados revelan una función positiva entre la complejidad de la historia de contacto y el porcentaje total de aciertos en la prueba de ajuste lector (excepto en el grupo con la historia más compleja). Se discuten los resultados enfatizando las funciones disposicionales de los diferentes tipos de historia en el ajuste lector, contrastándolas con la noción tradicional de conocimiento previo.
Based on the model of reading adjustment, the present study evaluated the interaction between the... more Based on the model of reading adjustment, the present study evaluated the interaction between the theoretical content of the text and the type of reading criteria established for performing tasks of reading adjustment. The participants were twenty psychology students assigned to one of four groups, which were differentiated by the type of theo-retical content of the text (mentalist or behavioral) and the variability of the criteria established for reading. The initial evaluation of the participants was followed by the intervention and a second evaluation. The findings show that establishing variable criteria has a positive effect on performance in the second evaluation, independent from the theoretical content of the text read. The results are discussed in terms of the role of the text's theoretical content in the formation of reading skills.
Physical Review D, 2011
We consider a real massless scalar field in 1+1 dimensions satisfying time-dependent Robin bounda... more We consider a real massless scalar field in 1+1 dimensions satisfying time-dependent Robin boundary condition at a static mirror. This condition can simulate moving reflecting mirrors whose motions are determined by the time-dependence of the Robin parameter. We show that particles can be created from vacuum, characterizing in this way a dynamical Casimir effect.
Lecture Notes in Computer Science, 2013
The Next Generation Air Transportation System (NextGen) plans to implement a series of automated ... more The Next Generation Air Transportation System (NextGen) plans to implement a series of automated tools into the National Airspace System to aid air traffic controllers (ATCos) in managing a two to three times increase in air traffic density. However, introducing automated technologies into a system like air traffic management (ATM) changes the responsibilities of the ATCo from an active controller to a passive monitor, which can result in lower levels of situation awareness (SA). To measure SA objectively in such a dynamic task as ATM, the Situation Present Awareness Method (SPAM) is often used. SPAM provides the operator with SA probes while the operator is performing the task. Some studies have shown that the use of SPAM to measure SA is intrusive because it provides the operator with a secondary task. The present study examines whether these intrusive effects of SPAM are present when the operator has achieved a high skill level at the time of test, and whether training operators to rely more or less on NextGen automated tools influence their performance when SPAM queries are presented as a secondary task.
Physical Review D, 2010
We consider a real massless scalar field inside a cavity with a moving mirror in a two-dimensiona... more We consider a real massless scalar field inside a cavity with a moving mirror in a two-dimensional spacetime, satisfying the Dirichlet or Neumann boundary condition at the instantaneous position of the boundaries, for an arbitrary and relativistic law of motion. Considering an arbitrary initial field state, we show that the exact value of the energy density in the cavity can be obtained by tracing back a sequence of null lines, connecting the value of the energy density at the given spacetime point to a certain known value of the energy density at a point in the region where the initial field modes are not affected by the boundary motion. We obtain the particular formulas for the energy density of the field and the quantum force acting on the boundaries for a vacuum, thermal, and a coherent state. We thus generalize a previous result in literature [17], where this problem is approached for only one mirror. For the particular cases of vacuum and Dirichlet boundary condition, nonrelativistic velocities, or in the limit of large length of the cavity, our results coincide with those found in the literature.
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2014
The current study measured driving performance using the Lane Change Test (LCT) and a Peripheral ... more The current study measured driving performance using the Lane Change Test (LCT) and a Peripheral Detection Task (PDT), to determine if stimulus modality (visual and auditory) and stimulus eccentricity would affect performance on the PDT. The peripheral stimuli were either small white circles or broadband noise bursts located either 13o or 19o to the left or right of the center lane. Participants were instructed to respond with left or right key presses to the stimuli’s relative location while performing the LCT. The cognitive load of participants was also varied, either no load, low load or high load, produced by the n-back task (no n-back, 0-back, 1-or 2-back). The results indicate that higher cognitive load leads to poorer driving performance, increased reaction time of PDTs, and higher subjective workload. This study supports previous research indicating driving performance suffers in response to increased cognitive load due to cognitive or attentional tunneling.
Physics Letters A, 2010
We investigate the exact behavior of the energy density of a real massless scalar field inside a ... more We investigate the exact behavior of the energy density of a real massless scalar field inside a cavity with a single moving mirror executing a resonant oscillatory law of motion, satisfying Dirichlet boundary conditions at finite temperature. Our results are compared with those found in literature through analytical approximative methods.
Oikos, 2002
According to the model of ideal free distribution, few or no assemblages will contain unused reso... more According to the model of ideal free distribution, few or no assemblages will contain unused resources as long as species are free to colonize areas where resources are available. Consequently, because several food resources for birds are available throughout Mexico (nectar, seeds and fruits, vertebrates, carrion and different types of invertebrates), we predicted that all assemblages from Mexico contain birds from the corresponding foraging guilds. However, severe climates may prevent colonization by certain birds. Thus, a second prediction was that, if assemblages with unused resources were found, these would be from localities with climates that pose extreme stress (either extremely high temperature and low rainfall, or extremely low temperature). We tested these predictions on bird assemblages from 77 localities that represent the entire range of climatic conditions found in Mexico. Only two assemblages containing unused resources were found. These were from the localities with lowest temperature and lowest rainfall, respectively. We observed that land bird assemblages in Mexico do not contain unused resources, except when climate selectively restricts colonization by species from certain foraging guilds. Therefore, we conclude that even assemblages with almost no species in common have a common guild structure based on food resources. Null models of competition would be more realistic if they were to incorporate such patterns in their regional species pools.
Journal of Physics: Conference Series, 2009
We study the exact solution for the energy density of a real massless scalar field in a twodimens... more We study the exact solution for the energy density of a real massless scalar field in a twodimensional spacetime, inside a non-static cavity with an arbitrary initial field state, taking into account the Neumann and Dirichlet boundary conditions. This work generalizes the exact solution proposed by Cole and Schieve in the context of the Dirichlet boundary condition and vacuum as the initial state. We investigate diagonal states, examining the vacuum and thermal field as particular cases. We also study non-diagonal initial field states, taking as examples the coherent and Schrödinger cat states.
Revista mexicana de …, 2011
... Lista comentada de la avifauna de Palenque, Chiapas. Michael A. Patten* 1, 2 , Héctor Gómez d... more ... Lista comentada de la avifauna de Palenque, Chiapas. Michael A. Patten* 1, 2 , Héctor Gómez de Silva 3 , Ana C. Ibarra 4 and Brenda D. Smith-Patten 1,5. ... Elanoides forficatus (Linnaeus, 1758) – Swallow-tailed Kite, milano tijereta. ...
Acta …, 2007
Se analizan de manera general las ambigüedades en el uso del término creatividad, y se presenta e... more Se analizan de manera general las ambigüedades en el uso del término creatividad, y se presenta el Modelo Interconductual de Comportamiento Creativo (MICC) en el que se propone una continuidad entre el comportamiento inteligente y el creativo, y en el que se reconocen como dimensiones relevantes de la inteligencia la variabilidad y la efectividad, en tanto que la correspondiente dimensión de la creatividad es la originalidad de criterios ante situaciones contingencialmente ambiguas. Se describen los resultados generales de los estudios derivados del MICC y se delinea la forma en que éstos pueden contribuir al replanteamiento de la labor del psicólogo en escenarios educativos.
Conservation Biology, 2008
Studies of species diversity, macroecology, and conservation are usually based on lists of specie... more Studies of species diversity, macroecology, and conservation are usually based on lists of species, but lists found in the scientific literature vary in completeness. The use of such data sets can produce misleading results, making it necessary to test species lists for completeness before undertaking an analysis. Species-richness estimators are useful for judging the completeness of species lists but have limitations. To add rigor to studies based on species lists, we propose that species lists should test for " omnipresent" taxa-species, genera, and families that occur throughout the region concerned-and for a minimum number of species and families. As a case study, we compared species assemblages in diverse habitats in Mexico and found that seven families and two genera of land birds are omnipresent in mainland Mexico (excluding treeless areas) and that the most depauperate assemblage known contains 35 species from 21 families. We concluded that a list of land birds from Mexico that lacks any of these omnipresent taxa or that contains fewer than 35 species or 21 families is incomplete. Similar analyses can be done for other taxa and other parts of the world. Tests for omnipresent taxa and for a minimum number of species and families can be used in combination with other existing criteria, such as species-richness functions, to better evaluate the completeness of species lists. Realistic results may be produced in macroecological and conservation studies only if they are based on reasonably complete species lists. Evaluación para Determinar si las Listas de Especies para Conservación y Macroecología son Completas: Caso de Estudio de Aves Terrestres Mexicanas
Chemosphere, 2010
A method for the determination of all polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinate... more A method for the determination of all polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinated dibenzofurans (PCDFs), and hexachlorobenzene (HCB) contained in production batches of pentachlorophenol (PCP) samples is presented. The method uses two sub-samples of the PCP sample to provide an effective dynamic range of 1:40,000,000. Following extraction of the samples and fractionation of the sample extracts, the extracts are analyzed by HRGC/HRMS, and the resulting data from both sub-samples are combined to generate the final data for each sample. Data from the analysis of 47 samples using this method are presented and show a ratio of concentrations of octachlorinated dibenzofuran (OCDF) to 2,3,7,8-tetrachlorinated dibenzofuran (TCDF) of approximately 4,000,000:1. The results show that four congeners dominate the ITEQ, which has an average value of 634 lg kg À1 (429 lg kg À1 WHO 2005 TEQ) in those samples.
Biodiversity and Conservation, 2009
With increased human populations and subsequent pressure to develop or farm land, the rate of fra... more With increased human populations and subsequent pressure to develop or farm land, the rate of fragmentation of tropical rainforests has accelerated in the past several decades. How native organisms respond to such fragmentation has been the subject of intense study in temperate ecosystems and at several tropical sites in Central and South America, but there has been little study of this phenomenon in Mexico, the country bridging the Neotropics and temperate North America. A reason for this neglect is an apparent lack of long-term data; however, such data can be obtained from ''non-traditional'' sources, such as birders and tour leaders. We make innovative use of such data, combining them with more traditional data (e.g., museum specimens) to create a record of occurrence for Palenque, Mexico, from 1900 to 2009, including a near-continuous presence-absence record since 1970. We analyzed these data using logistic regression and, importantly, recent statistical advances expressly for sighting records. As recently as the 1960s Palenque's forest was contiguous with that of Selva Lacandona to the east, but the protected area surrounding the famous ruins is now a forested island. As a result, various species formerly known from the site have disappeared, including species both large (Crax rubra, Penelope purpurascens, and Ara macao) and small (Notharchus hyperrhynchos, Malacoptila panamensis, Microrhopias quixensis, and Pachyramphus cinnamomeus). By contrast, several species of open areas or second growth have apparently colonized the area
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Papers by Hector John Silva