Thermodynamics of the classical spin-ice model with nearest neighbour interactions using the Wang-Landau algorithm

In this article we study the classical nearest-neighbour spin-ice model (nnSI) by means of Monte Carlo simulations, using the Wang-Landau algorithm. The nnSI describes several of the salient features of the spin-ice materials. Despite its simplicity it exhibits a remarkably rich behaviour. The model has been studied using a variety of techniques, thus it serves as an ideal benchmark to test the capabilities of the Wang Landau algorithm in magnetically frustrated systems. We study in detail the residual entropy of the nnSI and, by introducing an applied magnetic field in two different crystallographic directions ([111] and [100],) we explore the physics of the kagome-ice phase, the transition to full polarisation, and the three dimensional Kasteleyn transition. In the latter case, we discuss how additional constraints can be added to the Hamiltonian, by taking into account a selective choice of states in the partition function and, then, show how this choice leads to the realization of the ideal Kasteleyn transition in the system.Comment: 9 pages, 9 figure

LAS JORNADAS DE INTERCAMBIO ACADÉMICO PÚBLICO-PRIVADO: UN ÁMBITO DE FORMACIÓN, INTERCAMBIO Y VINCULACIÓN

Interdisciplinary and open discussion spaces between public and private research have been produced over the years and today they are presented in different ways and instances. However, the possibility of creating a "safe" space for discussion, for the professional and academic development of professionals related to science and technology, with the possibility of generating work and collaboration links, led us in 2013 a group of researchers with a look beyond the conjuncture to work in a framework of collaborative action and public-private exchange.Los espacios interdisciplinarios y de discusión abiertas entre la investigación pública y privada se han producido a lo largo de los años y hoy en día se presentan de diferente manera e instancias. Sin embargo, la posibilidad de crear un espacio “seguro” de discusión, para el desarrollo profesional y académico de profesionales relacionados con la ciencia y la tecnología, con la posibilidad de generar vínculos de trabajo y colaboración, nos llevó a que en el año 2013 un grupo de investigadores con una mirada más allá de la coyuntura se pusieran a trabajar en un marco de acción colaborativa y de intercambio publico privado

Communicative interaction in natural sciences lessons. A didactic analysis based on discursive circuits

En este trabajo se discute el rol de la comunicación en el aula de ciencias y se delimita una forma de análisis relacionada con circuitos de interacción discursiva. Se comparan tres tipos de circuitos para clases de ciencias experimentales: exposición abierta, diálogo guiado e indagación dialógica problematizadora. Los datos resumen los registros de un grupo de investigaciones interpretativas desarrolladas por el equipo en los últimos diez años, las cuales analizan el diálogo asociado a temas de ciencias y ciclos de actividad. Se presenta la escala de análisis resultante y los tipos de secuencia de intervenciones de docentes y alumnos. Desde las mismas se modelizan circuitos de comunicación que van desde la clase tradicional a una constructivista.Se concluye respecto a la necesidad de incluir la problemática de la comunicación en el aula a lo largo de la práctica educativa y de los procesos de formación docente, haciéndola formar parte tanto del diseño, como del desarrollo y evaluación de la tarea docente.This work argues the role of communication in natural sciences classrooms and delimits a way of analysis in relation to interactive discursive circuits. Three types of circuits for experimental sciences lessons are compared: open exposition, guided dialog and problematic dialogic inquiry. The data summary the records of a group of interpretative research developed by the team in the last years ten years, which analyses the dialogue associated with science topics and cycles of activity. The resulting scale of analysis and types of intervention sequences held by teachers and students are presented. Based on them, communication circuits are modeled ranging from the traditional classroom to a constructivist one. It is concluded in relation to the need of including the problem of communication in the classroom throughout the educational practice and the processes of teacher training, making it part of the design, development and evaluation of the teaching task

Spectral properties of a short-range impurity in a quantum dot

The spectral properties of the quantum mechanical system consisting of a quantum dot with a short-range attractive impurity inside the dot are investigated in the zero-range limit. The Green function of the system is obtained in an explicit form. In the case of a spherically symmetric quantum dot, the dependence of the spectrum on the impurity position and the strength of the impurity potential is analyzed in detail. It is proven that the confinement potential of the dot can be recovered from the spectroscopy data. The consequences of the hidden symmetry breaking by the impurity are considered. The effect of the positional disorder is studied.Comment: 30 pages, 6 figures, Late

La lógica difusa como un medio para identificar y valorar las alteraciones de conducta en niños a nivel de educación básica: primaria y secundaria

Esta investigación toma como referencia la problemática económica, educativa y social de los niños con trastornos de conducta –niños problema- y justifica la aplicación de la lógica difusa como una técnica de ingeniería para optimizar la identificación oportuna y eficaz de los trastornos del comportamiento en niños y adolescentes. Muestra cómo adquirir y analizar datos ambiguos, vagos y llenos de incertidumbre provenientes de las variables de entrada para conseguir resultados de valoración precisos de cada una de las tipologías presentadas por los niños con problemas de conducta. Los trastornos del comportamiento analizados en este trabajo son: Hiperactividad (H), Déficit de Atención con Hiperactividad (DAH), Trastorno de conducta (TC) y Déficit de Atención (DA).Palabra(s) Clave(s): déficit de atención, hiperactividad, lógica difusa, trastorno de conducta

Mating system analysis and genetic diversity of Parkia multijuga Benth. one native tree Species of the Amazon.

The Amazonian native tree species Parkia multijuga has potential silvicultural characteristics that can be utilized to productive plantations. Understanding its mating system is necessary to delineate the methods for the breeding of the species, the collection of seeds for conservation, and the use of seedlings for production plantations. The aim of this study is to evaluate the mating system and population genetic diversity of P. multijuga, using molecular markers

Agrobiodiversidade na região do Rio Amanari, Urucará-AM: suas variedades crioulas.

Sabemos que a região norte do Brasil é rica em fauna e flora e que essa riqueza deve ser protegida e conhecida, além disso, existe uma particularidade de sistemas de produção que são reconhecidos como sustentáveis e permitem a coexistência de espécies, sejam em quintais agroecológicos ou monocultivos. Buscou-se com esse trabalho realizar o levantamento de populações caboclas de milho, mandioca e feijão cultivados pelos agricultores tradicionais da região do rio Amanari, Urucará, na busca de conhecimento e variedades locais para conservação in situ. Em vista da grande erosão genética que é vivida hoje realizar a conservação de materiais vegetais que são pouco utilizados é de fundamental importância para utilização em futuros melhoramentos. Para desenvolver essa pesquisa adotou-se a metodologia do Diagnóstico Rural Participativo, permitindo alcançar o levantamento de 64 espécies vegetais divididas em 33 famílias botânicas em propriedades não maiores que 10 hectares.Título em inglês: Agrobiodiversity in the Rio Amanari Region, Urucará-AM: Its Creole Varieties

Determination of the mating system of tucumã palm using microsatellite markers.

A palmeira Astrocaryum aculeatum produz frutos comestíveis, utilizados na alimentação por populações indígenas, tradicionais e urbanas. Esta espécie é incipientemente domesticada e pouco estudada apesar de sua importância econômica para pequenos produtores e extrativistas. Estudos do sistema reprodutivo são necessários para conservação e uso dos recursos genéticos da espécie. O objetivo foi estimar parâmetros do sistema reprodutivo do tucumã-do-Amazonas usando marcadores microssatélites

Climate change impact on the distribution of forest species in the Brazilian Amazon.

Studies using ecological niche models highlight the vulnerability of forest species to climate change. This work aimed to analyze the distribution of timber species Aspidosperma desmanthum, Cariniana micranta, Clarisia racemosa, Couratari oblongifolia, and Vouchysia guianensis, which are targets of deforestation, to predict the impacts of climate change and identify areas for their conservation in the Amazon. For this purpose, 37 environmental variables were used, including climatic and edaphic factors. The models were fitted using five algorithms, and their performance was evaluated by the metrics Area Under the Curve (AUC), True Skill Statistic, and Sorensen Index. The deforestation analysis was conducted using data accumulated over a period of 14 years. The study indicated that under the most pessimistic predictions, considering continued high emissions of greenhouse gases (GHGs) from the use of fossil fuels, SSP5–8.5, potential habitat loss for the studied species was more significant. Analyses of the species show that the Western Amazon has a greater climatic suitability area for the conservation of its genetic resources. Further study of the accumulated deforestation over 14 years showed a reduction in area for all species. Therefore, in situ conservation policies and deforestation reduction are recommended for the perpetuation of the analyzed forest species