Juan J. Morrone y Jorge Llorente Busquets (eds). 2003. Una perspectiva latinoamericana de la biogeografía. Las prensas de ciencias. Universidad Nacional Autónoma de México. México, D.F. 307pp

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A New Species of \u3ci\u3eAcanthobothrium\u3c/i\u3e Van Beneden, 1849 (Eucestoda: Tetraphyllidea: Onchobothriidae) in \u3ci\u3eDasyatis longus\u3c/i\u3e Garman (Chondrichthyes: Myliobatiformes: Dasyatididae) from Chamela Bay, Jalisco, Mexico

A new species of Acanthobothrium in Dasyatis longus from Chamela Bay, Jalisco, Mexico, is a member of a presumed clade of species diagnosed by being anapolytic or nearly so, having more than 100 testes per proglottis, with immature and mature proglottides wider than long to square, aspinose scolex, muscular bothridia fused to the scolex at their posterior ends, H- to V-shaped ovaries, relatively short symmetrical to asymmetrical ovarian arms that extend anteriorly to, or nearly to, the cirrus sac, and vitellaria arranged in fields rather than a single row of follicles. The new species most closely resembles Acanthobothrium terezae from the freshwater stingray Potamotrygon motoro in the following characters: bothridial hooks longer than 200 μm with inner hooks having bent asymmetrical prongs, an average of 130-140 testes per proglottis, and shallow genital atria located posterior to midline of proglottis. The new species differs from A. terezae by having outer hooks approximately the same size and shape as the inner hooks, inner hooks averaging 230 μm rather than 313 μm in total length, and cirrus sacs averaging 255 μm rather than 450 μm in length. The new species is unique among all described species of Acanthobothrium by having a cleft in the posterior margin of each apical bothridial pad. The apparent close relationship of the new species to one inhabiting a Neotropical freshwater stingray provides support for the hypothesized Pacific marine ancestry of Neotropical freshwater stingrays and raises the possibility that the Neotropical freshwater stingrays may not be monophyletic

Phylogenetic relationships and biogeography of the genus Algansea Girard (Cypriniformes: Cyprinidae) of central Mexico inferred from molecular data

42 pages, 2 additional files, 6 figures, 1 table.[Background] The genus Algansea is one of the most representative freshwater fish groups in central Mexico due to its wide geographic distribution and unusual level of endemicity. Despite the small number of species, this genus has had an unsettled taxonomic history due to high levels of intraspecific morphological variation. Moreover, several phylogenetic hypotheses among congeners have been proposed but have had the following shortcomings: the use of homoplasious morphological characters, the use of character codification and polarisation methods that lacked objectivity, and incomplete taxonomic sampling. In this study, a phylogenetic analysis among species of Algansea is presented. This analysis is based upon two molecular markers, the mitochondrial gene cytochrome b and the first intron of the ribosomal protein S7 gene.[Results] Bayesian analysis based on a combined matrix (cytochrome b and first intron S7) showed that Algansea is a monophyletic group and that Agosia chrysogaster is the sister group. Divergence times dated the origin of the genus around 16.6 MYA, with subsequent cladogenetic events occurring between 6.4 and 2.8 MYA. When mapped onto the molecular phylogenetic hypothesis, the character states of three morphological characters did not support previous hypotheses on the evolution of morphological traits in the genus Algansea, whereas the character states of the remaining six characters partially corroborated those hypotheses.[Conclusions] Monophyly of the genus Algansea was corroborated in this study. Tree topology shows the genus consists of three main lineages: Central-Eastern, Western, and Southern clades. However, the relationships among these clades remained unresolved. Congruence found between the available geological and climatic history and the divergence times made it possible to infer the biogeographical history of Algansea, which suggested that vicariance events were responsible for the evolutionary history of the genus. Interestingly, this pattern was shared with other members of the freshwater fish fauna of central Mexico. In addition, molecular data also show that some morphological traits alleged to represent synapomorphies in previous studies were actually homoplasies. Others traits were corroborated as synapomorphies, particularly in those species of a subgroup corresponding with the Central-Eastern clade within Algansea; this corroboration is interpreted as a result of evolutionary adaptations.This study was partially funded by grants from CGL2006-12325/BOS, the program PAPIIT-UNAM-IN209608, and CONACYT (grant number 83043) to GPPDL. RPR thank the Consejo Nacional de Ciencia y Tecnología for the scholarship.Peer reviewe

Sistema de navegación para vehículos agrícolas autónomos

Este proyecto trata sobre un sistema de navegación aplicado al sector agrícola. Su implantación en vehículos o robots agrícolas podrían dotar a estos de una navegación semiautónoma o autónoma integral. El principio básico de funcionamiento se basa, en primera estancia, en guardar una ruta personalizada y adaptada a cada parcela en la que se vaya a trabajar, estas rutas se denominan "tracks" o "trazadas". Una vez se tenga estas rutas adquiridas, estas se vuelcan al sistema de control del vehículo y utilizando la trazada correspondiente a la parcela en la que se esté trabajando y comparando su posición en tiempo real. Decidirá mediante su programación cual será su rumbo y dirección a tomar, para seguir de forma precisa la trazada, además de hacerlo a una velocidad optima para el laboreo que esté realizando en ese momento. Este sistema de navegación está enfocado a un tipo de cultivo en particular: en concreto a todo aquel que posea una plantación de árboles (ya sean frutales de hueso, frutos secos, plantaciones para madera, etc). Esta parte del sector actualmente no está provista de sistemas de navegación, por su gran dificultad al presentar parcelas repletas de obstáculos: los propios árboles

Lista patrón de los tiburones, rayas y quimeras (Chondrichthyes, Elasmobranchii, Holocephali) de México

Llista patró dels taurons, rajades i quimeres (Chondrichthyes, Elasmobranchii, Holocephali) de Mèxic Es presenta una relació de les espècies de taurons, rajades  i quimeres (condrictis) que han estat registrades a les aigües territorials de Mèxic, basada en revisions de bases de dades, literatura, examen físic dels espècimens de col·leccions científiques i registres d’exemplars recol·lectats en treballs de camp durant els darrers quatre anys i que no han estat publicats. La relació conté informació de 214 espècies de condrictis que, com a mínim, han estat registrades a les aigües marines i salobroses de Mèxic, pertanyents a 84 gèneres, 40 famílies i 14 ordres. S’hi inclouen vuit espècies de quimeres, 95 de batoïdeus i 111 de taurons. La condrictiofauna mexicana és una de les més riques del món, amb el 17,3% o més de les espècies conegudes. A més a més, s’ hi inclouen 16 espècies que és probable que siguin presents a Mèxic atesos els seus patrons de distribució.Checklist of sharks, rays and chimaeras (Chondrichthyes, Elasmobranchii, Holocephali) from Mexico We present an annotated checklist of the species of sharks, rays and chimaeras (chondrichthyan fishes) occurring in Mexican waters, based on a thorough review of the literature and electronic database searches, examination of museum collection specimens, and unpublished records obtained during fieldwork conducted in the last four years. The checklist contains information of at least 214 species of chondrichthyan fishes that occur in Mexican marine and brackish waters, assigned to 84 genera, 40 families and 14 orders. It includes eight species of chimaeras, 95 batoids and 111 sharks. Condrichthyan fauna in Mexico is one of the richest in the world, with almost 17.3% of the known species. An additional  16 species are included  as their occurrence in Mexican marine waters is probable according to distributional patterns.Se presenta un listado anotado de las especies de tiburones, rayas y quimeras (Condrictios) que han sido registrados en las aguas territoriales de México, basado en revisiones de bases de datos, literatura, examinación física de los especímenes de colecciones científicas y de registros de ejemplares recolectados en campo durante los últimos cuatro años y que no han sido publicados. El listado contiene información de al menos 214 especies de condrictios que se han registrado en las aguas marinas y salobres de México, pertenecientes a 84 géneros, 40 familias y 14 órdenes. Se incluyen ocho especies de quimeras, 95 de batoideos y 111 de tiburones. La condrictiofauna mexicana es una de las más ricas a nivel mundial, con al menos 17.3% de las especies conocidas. Adicionalmente, 16 especies, se incluyen como especies probables que ocurran en México debido a sus patrones de distribución.Palabras clave: Condrictios, Elasmobranquios, Batoideos, Quimeras, México

Fluorinated vs Nonfluorinated PR2(biaryl) Ligands and Their [AuCl(L)] Complexes: Synthesis, X-ray Structures, and Computational Study of Weak Interactions. Bond, No Bond, and Beyond

Producción CientíficaSix fluorinated PR2(biaryl) phosphines, Ln, with R = Ph, Cy and biaryl = C6H4–C6F5, C6F4–C6H5, C6F4–C6F5, have been prepared. Their [AuCl(Ln)] complexes and H congeners with PhJohnPhos or CyJohnPhos have been studied in order to examine the interactions that bring the distal aryl close to the Au–Cl bond region. X-ray, DFT structure optimization, QTAIM, and NCI methods allow for some understanding of the forces involved. The “no bond” noncovalent distal-aryl/Au–Cl weak interactions are produced at forced short distances achieved under intramolecular structural ligand pressure. Enhanced vdW distal-aryl/Au interactions at “no bond” distances shorter than the sum of Au and C vdW radii and weaker distal-aryl/Cl interactions at “no bond” distances beyond the sum of Cl and C vdW radii counterbalance the unfavorable structural distortion of the free ligand, providing some extra stability of the molecule on the order of 2–10 kcal mol–1. The F substituents in the distal aryl induce shorter aryl distances to the Au–Cl zone, pointing overall to stronger π-aryl polarization as being mainly responsible for the NCIs with gold. The interactions in the C···Cl zone, where the distances are larger than the sum of vdW radii, contribute only about 5%, according to energy estimations using NBOs.Ministerio de Economía, Industria y Competitividad (Projects CTQ2016-80913-P and CTQ2017-89217-P)Junta de Castilla y León (Projects VA051P17 and VA062G18)Ministerio de Economía, Industria y Competitividad FPI scholarship (BES-2017-080726

NECESIDAD DE PERFECCIONAR EL PROCESO DE ENSEÑANZAAPRENDIZAJE DE LAS CIENCIAS NATURALES EN LA EDUCACIÓN PRIMARIA, EN CORRESPONDENCIA CON EL VERTIGINOSO DESARROLLO CIENTÍFICO ACTUAL

This article accounts for the theoretical assumption based on the need of setting up new relationships between the teaching-learning process of natural sciences and the contemporary research activity contextualized in Elementary Education. It stems from an investigative process that has been accomplished in Calixto García Municipality from Holguín Province. As an outcome of the theoretical linkages proposed, new qualities arise to enrich the existing theoretical construct concerning the research activity in the primary level. It is of utmost importance to highlight that the student´s psychopedagogical features have been highly considered. It can be asserted that this allows the setting out of the chief theoretical principles that support the scientific research in primary students. Furthermore, there is a trend to a new characteristic in the students: their scientific identity which is an effect of the application of the new theoretical relationships in the pedagogical practice. The scientific identity is defined and operationalized that provides a tinge of novelty, currency, pertinence and update to this investigation.  En este artículo se argumenta, tomando en cuenta la tesis que sustentan los autores, la necesidad de aproximar el proceso de enseñanza-aprendizaje de la asignatura Ciencias Naturales, la cual se imparte en el segundo ciclo de la Educación Primaria, a la actividad científico-investigadora contemporánea. Lo anterior es consecuencia de un proceso investigativo, realizado en el ámbito de la referida educación, en el municipio Calixto García de la provincia Holguín, a partir del cual se justifica la relación que se puede establecer entre los rasgos distintivos de la actividad científico-investigadora y la estructura del contenido de la asignatura Ciencias Naturales. De estas relaciones emergen nuevas cualidades, que enriquecen el constructo teórico existente, relacionado con la actividad investigativa del nivel primario. Todo ello, lógicamente, en estrecha correspondencia con las potencialidades psicopedagógicas de los escolares. Estas nuevas relaciones permiten establecer los principales sustentos teóricos de la actividad científica escolarizada. Con la aplicación del nuevo constructo teórico en la práctica educativa se aprecia cierta polaridad positiva hacia la formación de una nueva cualidad en los escolares primarios: la identidad científica, categoría que se define y operacionaliza, dotando el proceso investigativo de novedad científica, pertinencia y actualidad

Las matemáticas como recurso para estimular el desarrollo de la flexibilidad como cualidad de las potencialidades creadoras de los estudiantes en el preuniversitario

Mathematics in Cuban Senior High School require students with capacity to face and solve problems, and they should be relevant and should respond to social needs (learning how to do), (learning to be), (How to Live Together), and (How to Learn). This certainly means developing creativity from school, because the appropriation of knowledge can be useless, if you do not know how to use it in order to grow up as a person and to deal with today and future problems, effectively and creatively. This paper is aimed to stimulate the development of creativity, particularly the flexibility of thought from pre-university students. This epistemological study allowed revealing theoretical and methodological limitations in theoretical assumptions that support the subject of study, and proposing ideas aimed to overcome these limitations. Starting from the analysis of the theoretical foundations of creativity and different approaches for their study, a characterization of the concept of creativity is made and its regularities are determined within a socio-cultural environment in the teaching-learning process of Mathematics in Cuban High School Education. The learning approach theoretically supported, takes as a practical referent the learning process of mathematics in the IPUEC "Ricondo Ismael Fernandez", in the municipality of Sagua de Tánamo Holguin.   Key words: stimulation, creativity, creative potential, creative approach, teaching and learning.  Las Matemáticas en el preuniversitario cubano exigen de los estudiantes la capacidad de enfrentar y resolver problemas, y que los mismos sean pertinentes y respondan a las necesidades sociales (Aprender a Hacer, Aprender a Ser, Aprender a Convivir, y Aprender a Aprender). Esto sin duda alguna, implica desarrollar la creatividad desde la escuela, ya que la apropiación del conocimiento puede resultar inútil si no se sabe emplear este para crecer como persona y hacer frente a los problemas de hoy y del futuro con eficacia y creatividad. Este trabajo tiene como objetivo estimular el desarrollo de la creatividad, en particular la flexibilidad del pensamiento, de los estudiantes del preuniversitario. El estudio epistemológico permitió revelar limitaciones teórico-metodológicas en presupuestos teóricos que sustentan el objeto de estudio y proponer ideas tendentes a la superación de esas limitaciones. Se parte del análisis de los fundamentos teóricos de la creatividad y de los diferentes enfoques para su estudio. Se realiza una caracterización del concepto creatividad y se determinan las regularidades del mismo en un ambiente sociocultural del proceso de enseñanza-aprendizaje de las Matemáticas en la Educación Preuniversitaria Cubana. El enfoque de aprendizaje que se fundamenta teóricamente toma como referente práctico el proceso de aprendizaje de las Matemáticas en el IPUEC “Ismael Ricondo Fernándezˮ, en el municipio Sagua de Tánamo de la provincia de Holguín.   Palabras clave: estimulación, creatividad, potencialidades creadoras, enfoque creativo, enseñanza aprendizaje.   Abstract   Mathematics in Cuban Senior High School require students with capacity to face and solve problems, and they should be relevant and should respond to social needs (learning how to do), (learning to be), (How to Live Together), and (How to Learn). This certainly means developing creativity from school, because the appropriation of knowledge can be useless, if you do not know how to use it in order to grow up as a person and to deal with today and future problems, effectively and creatively. This paper is aimed to stimulate the development of creativity, particularly the flexibility of thought from pre-university students. This epistemological study allowed revealing theoretical and methodological limitations in theoretical assumptions that support the subject of study, and proposing ideas aimed to overcome these limitations. Starting from the analysis of the theoretical foundations of creativity and different approaches for their study, a characterization of the concept of creativity is made and its regularities are determined within a socio-cultural environment in the teaching-learning process of Mathematics in Cuban High School Education. The learning approach theoretically supported, takes as a practical referent the learning process of mathematics in the IPUEC "Ricondo Ismael Fernandez", in the municipality of Sagua de Tánamo Holguin.   Key words: stimulation, creativity, creative potential, creative approach, teaching and learning

Emerging pathogens in the central nervous system: a cerebral abscess by Streptococcus porcinus

Brain abscesses can cause an incapacitating neurological deicit in up to 50% of patients, thus the reduction of these sequelae becomes the main goal of its timely and speciic surgical and medical treatment. With technological advances in bacteriological identiication and diagnostic imaging, the clinical suspicion can be conirmed, and the speciic etiological agent can be identiied in a larger number of cases. New pathogens have emerged through this process, such as Streptococcus porcinus, in which the ability to affect the central nervous system has not been documented. A clinical case is presented of a brain abscess in an immunocompetent patient, and its favorable response to surgical drainage t hrough a skull burr h ole and nee dle aspiration with antibiotic therapy (ceftriaxone, metronidazole and vancomycin) is discussed