86 research outputs found

    The Use of Multivariate Analysis in Tropical Grass and Legume Seed Production in Cuban Regions

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    Seed production is an important activity in developing countries where pastures are the main source for animal feeding (Febles et al. 2003). Another outstanding aspect is the mathematical analysis used when a large number of species, varieties and ecotypes are used in the same study. The objective of this paper was to examine the use of multivariate analysis in studies on the effects of edaphoclimatic factors on seed production from tropical grasses and legumes

    Rapid test for identification of a highly transmissible Mycobacterium tuberculosis beijing strain of sub-Saharan origin

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    The development of a rapid test to identify Mycobacterium tuberculosis Beijing isolates and specifically strain GC1237, coming from a sub-Saharan country, is needed due to its alarming wide spread on Gran Canaria Island (Spain). A rapid test that detects IS6110 present between dnaA and dnaN in the Beijing strains and in a specific site for GC1237 (Rv2180c) has been developed. This test would be a useful tool in the surveillance of subsequent cases

    Connecting Network Properties of Rapidly Disseminating Epizoonotics

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    To effectively control the geographical dissemination of infectious diseases, their properties need to be determined. To test that rapid microbial dispersal requires not only susceptible hosts but also a pre-existing, connecting network, we explored constructs meant to reveal the network properties associated with disease spread, which included the road structure.Using geo-temporal data collected from epizoonotics in which all hosts were susceptible (mammals infected by Foot-and-mouth disease virus, Uruguay, 2001; birds infected by Avian Influenza virus H5N1, Nigeria, 2006), two models were compared: 1) 'connectivity', a model that integrated bio-physical concepts (the agent's transmission cycle, road topology) into indicators designed to measure networks ('nodes' or infected sites with short- and long-range links), and 2) 'contacts', which focused on infected individuals but did not assess connectivity.THE CONNECTIVITY MODEL SHOWED FIVE NETWORK PROPERTIES: 1) spatial aggregation of cases (disease clusters), 2) links among similar 'nodes' (assortativity), 3) simultaneous activation of similar nodes (synchronicity), 4) disease flows moving from highly to poorly connected nodes (directionality), and 5) a few nodes accounting for most cases (a "20:80" pattern). In both epizoonotics, 1) not all primary cases were connected but at least one primary case was connected, 2) highly connected, small areas (nodes) accounted for most cases, 3) several classes of nodes were distinguished, and 4) the contact model, which assumed all primary cases were identical, captured half the number of cases identified by the connectivity model. When assessed together, the synchronicity and directionality properties explained when and where an infectious disease spreads.Geo-temporal constructs of Network Theory's nodes and links were retrospectively validated in rapidly disseminating infectious diseases. They distinguished classes of cases, nodes, and networks, generating information usable to revise theory and optimize control measures. Prospective studies that consider pre-outbreak predictors, such as connecting networks, are recommended

    La psicología educacional y el sistema de educación en Cuba

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    Tunable Porous Organic Crystals: Structural Scope and Adsorption Properties of Nanoporous Steroidal Ureas

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    Previous work has shown that certain steroidal bis-(N-phenyl)ureas, derived from cholic acid, form crystals in the P61 space group with unusually wide unidimensional pores. A key feature of the nanoporous steroidal urea (NPSU) structure is that groups at either end of the steroid are directed into the channels and may in principle be altered without disturbing the crystal packing. Herein we report an expanded study of this system, which increases the structural variety of NPSUs and also examines their inclusion properties. Nineteen new NPSU crystal structures are described, to add to the six which were previously reported. The materials show wide variations in channel size, shape, and chemical nature. Minimum pore diameters vary from ∼0 up to 13.1 Å, while some of the interior surfaces are markedly corrugated. Several variants possess functional groups positioned in the channels with potential to interact with guest molecules. Inclusion studies were performed using a relatively accessible tris-(N-phenyl)urea. Solvent removal was possible without crystal degradation, and gas adsorption could be demonstrated. Organic molecules ranging from simple aromatics (e.g., aniline and chlorobenzene) to the much larger squalene (Mw = 411) could be adsorbed from the liquid state, while several dyes were taken up from solutions in ether. Some dyes gave dichroic complexes, implying alignment of the chromophores in the NPSU channels. Notably, these complexes were formed by direct adsorption rather than cocrystallization, emphasizing the unusually robust nature of these organic molecular hosts

    Unburying the Mirror: An Autoethnography of a Latino Teacher Who Left the Classroom

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    Despite the expressed need for bicultural teachers, research on teacher attrition has demonstrated that a growing number of bicultural educators are leaving the classroom. Bicultural male teachers, in particular, experience high rates of teacher attrition. Schools, unfortunately, are contexts in which Latino male teachers are constantly experiencing dilemmas related specifically to both their gendered and racialized positionality as males of color. Grounded in Antonia Darder’s critical bicultural framework, this autoethnographic study explored the complex factors that drive Latino male teachers out of the classroom, through an in-depth and grounded examination of a Latino male teacher who left the classroom. The study contributes to the conversation on bicultural teacher attrition, gendered relations, and their relationship to both teacher preparation and the education of bicultural students. Furthermore, the study explored how racism, sexism, classism, trauma, and heteronormativity mitigate the experiences of Latino male teachers, and how these manifest themselves through the hidden curriculum, asymmetrical relations of power, gendered essentialism, policing of behavior, the culture of silence, conditions of isolation, and disabling cultural response patterns. The implications of such factors in the life of one Latino male teacher are carefully analyzed and discussed, in an effort to consider their significance in rethinking teacher preparation programs, with respect to the needs of Latino males. Moreover, the study offers an engagement with critical autoethnography as a significant tool of reflection in the educational process and emancipatory process of bicultural teachers
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