Novel intron markers to study the phylogeny of closely related mammalian species

BACKGROUND: Multilocus phylogenies can be used to infer the species tree of a group of closely related species. In species trees, the nodes represent the actual separation between species, thus providing essential information about their evolutionary history. In addition, multilocus phylogenies can help in analyses of species delimitation, gene flow and genetic differentiation within species. However, few adequate markers are available for such studies. RESULTS: In order to develop nuclear markers that can be useful in multilocus studies of mammals, we analyzed the mammalian genomes of human, chimpanzee, macaque, dog and cow. Rodents were excluded due to their unusual genomic features. Introns were extracted from the mammalian genomes because of their greater genetic variability and ease of amplification from the flanking exons. To an initial set of more than 10,000 one-to-one orthologous introns we applied several filters to select introns that belong to single-copy genes, show neutral evolutionary rates and have an adequate length for their amplification. This analysis led to a final list of 224 intron markers randomly distributed along the genome. To experimentally test their validity, we amplified twelve of these introns in a panel of six mammalian species. The result was that seven of these introns gave rise to a PCR band of the expected size in all species. In addition, we sequenced these bands and analyzed the accumulation of substitutions in these introns in five pairs of closely related species. The results showed that the estimated genetic distances in the five species pairs was quite variable among introns and that this divergence cannot be directly predicted from the overall intron divergence in mammals. CONCLUSIONS: We have designed a new set of 224 nuclear introns with optimal features for the phylogeny of closely related mammalian species. A large proportion of the introns tested experimentally showed a perfect amplification and enough variability in most species, indicating that this marker set can be very helpful in multilocus phylogenetics of mammals. Due to the lower variability and stronger stochasticity of nuclear markers with respect to mitochondrial genes, studies should be designed to make use of several markers like the ones designed here

Validación de las alturas de un plan de vuelo

El objetivo de este trabajo consiste en verificar un plan de vuelo de un UAV (Unmanned Aerial Vehicle) contra posibles colisiones que se puedan producir con el nivel del terreno y teniendo en cuenta que no puede entrar en el espacio aéreo controlado. Para poder verificarlo se analizan los diferentes requisitos propuestos por el usuario, e.g: detectar posibles conflictos del plan de vuelo propuesto, la presencia de márgenes de seguridad, el formato de los datos de la altura del cartográfico, etc. También, se informará al usuario de la altura mínima obtenida en un flight plan completo, ya que será la altura más crítica que adquirirá el avión en todo su recorrido. El avión tendrá especificado un flight plan en el cual podrá realizar dos tipos de trayectorias diferentes (LEGs). La primera consiste en una línea recta (Trackto- Fix) y la segunda en un arco de circunferencia (Radius-to-Fix). Los datos de entrada de la aplicación, que verificará el plan de vuelo, estarán compuestos por un conjunto de matrices de alturas (cada matriz corresponde a la elevación del terreno por el que pasa un LEG propuesto) y los datos de cada LEG. En ambos tipos de LEGs será necesario conocer la posición inicial y final, así como la altura en dichas posiciones, y en el caso del Radius-to-Fix, además de los datos anteriores, se necesitará el centro y el sentido de giro (clockwise o anticlockwise). La implementación de las trayectorias anteriores se ha realizado mediante dos algoritmos que identifican las posiciones por las que volará el avión y así comprobar el principal objetivo, es decir, que no se produzca una colisión. La aplicación analizará cada uno de los LEGs y comprobará si es seguro (no hay colisión y no entra en espacio aéreo controlado). Si el flight plan es correcto se informará de la altura mínima obtenida por el avión en todo el trayecto. Si no es correcto se informará que el plan de vuelo es erróneo

Francisco Giner de los Ríos o el arte de forjar almas

Este trabajo tiene por objeto dibujar el perfil educador de Francisco Giner de los Ríos, el hombre más carismático de la Institución Libre de Enseñanza. Apoyándonos sobre todo en el testimonio escrito de algunos de sus discípulos más cualificados, estas páginas reflejan la actividad de un maestro universitario a pie de obra. Giner superó el horizonte de su época porque se opuso al memorismo estéril y construía el saber con sus discípulos, planteando problemas e invitando a encontrar soluciones. Era, en definitiva, un educador moderno, de corte europeo. Y lo era allá donde estuviera; por eso, con su buen hacer pero, sobre todo, con su ser, iluminó una herencia pedagógica de cuatro décadas, ya en el siglo XX. Que a los educadores de hoy, bien entrado el XXI, nos sirva para reforzar nuestra responsabilidad y redoblar esfuerzos en la tarea, seguramente, más comprometida que existe.The aim of these lines is to present the portrait of the most charismatic educator of the Institución Libre de Enseñanza: Francisco Giner de los Ríos. Building our discourse on the written testimony of some of his most qualified disciples, these pages show the activity of a university teacher —not just a professor—. Giner exceeded the horizon of his time because he opposed the sterile memorization and built knowledge with his disciples, not only proposing problems but also inviting them to solve them. In short, he was a modern educator who was aware of the European way of teaching. And he was all these things regardless of the place where he was. Therefore, with his savoir faire, but above all thanks to his great way of being, he lit a pedagogical legacy of four decades within the twentieth century. His life may be a good mirror in which educators could see their duties and efforts reflected

Una estratègia d'atenció a la diversitat : l'aula flexible

Els autors de l'article, components de l'Equip d'Atenció a la Diversitat (EAD) de l'IES de l'Escola Industrial de Sabadell, presenten estratègies d'atenció a la diversitat emprades dins aquest centre durant el curs 1995-1996. S'emfatitza especialment l'aula flexible, com a espai educatiu integrador, obert i interdisciplinari que contribueix a adequar l'oferta formativa del centre a un grup d'alumnes amb problemes greus d'aprenentatge dins de les condicions que ofereix l'aula ordinària.Los autores del artículo, componentes del Equip d'Atenció a la Diversitat (EAD) del IES de la Escola Industrial de Sabadell, presentan estrategias de atención a la diversidad utilizadas dentro de este centro durante el curso 1995-1996. Se da especial atención al aula flexible, como un espacio educativo integrador, abierto e interdisciplinario que contribuye a adecuar la oferta formativa del centro a un grupo de alumnos con problemas graves de aprendizaje dentro de las condiciones que ofrece el aula ordinaria.The authors of the present article, who are all of them members of the EAD in the IES of the Sabadell's Industrial College, show the different strategies that have been used there during the course 1995-96 with the aim of integrating the diversity existing in its classrooms. Particularly, they give emphasis to the Flexible Classroom, being open, interdisciplinary and promoting integration, as well as it matches the educational profile of the school to the special needs of students with learning problems inside the ordinary classroom

Electric charging of dust aggregates and its effect on dust coagulation in protoplanetary disks

Mutual sticking of dust aggregates is the first step toward planetesimal formation in protoplanetary disks. In spite that the electric charging of dust particles is well recognized in some contexts, it has been largely ignored in the current modeling of dust coagulation. In this study, we present a general analysis of the dust charge state in protoplanetary disks, and then demonstrate how the electric charging could dramatically change the currently accepted scenario of dust coagulation. First, we describe a new semianalytical method to calculate the dust charge state and gas ionization state self-consistently. This method is far more efficient than previous numerical methods, and provides a general and clear description of the charge state of gas-dust mixture. Second, we apply this analysis to early evolutionary stages where the dust has been thought to grow into fractal ($D \sim 2$) aggregates with a quasi-monodisperse (i.e., narrow) size distribution. We find that, for a wide range of model parameters, the fractal growth is strongly inhibited by the electric repulsion between colliding aggregates and eventually "freezes out" on its way to the subsequent growth stage involving collisional compression. Strong disk turbulence would help the aggregates to overcome this growth barrier, but then it would cause catastrophic collisional fragmentation in later growth stages. These facts suggest that the combination of electric repulsion and collisional fragmentation would impose a serious limitation on dust growth in protoplanetary disks. We propose a possible scenario of dust evolution after the freeze-out. Finally, we point out that the fractal growth of dust aggregates tends to maintain a low ionization degree and, as a result, a large magnetorotationally stable region in the disk.Comment: 14 pages, 7 figures, the effect of stellar X-ray ionization included, conclusions unchanged, accepted for publication in Ap

Enfoques de aprendizaje y rendimiento académico en Educación Secundaria

[Resumen] El estudio de los factores que infuyen, y en algunos casos determinan, el rendimiento académico de nuestros alumnos es un campo fértil de investigación en el ámbito educativo. En la presente investigación comprobamos la relación que existe, si existe, entre el tipo de enfoque hacia el aprendizaje de los alumnos y su rendimiento académico, distinguiendo entre enfoques profundos y superficiales. La muestra se conforma con alumnos de Educación Secundaria durante el curso académico 2006-2007. Además, se observa la relación que pudiera existir entre el hecho de que un profesor les imparta más de una asignatura y las calificaciones obtenidas.[Abstract] The study of the factors that influence, and in some cases determines, the academic results of our students is a fertile field of research from the educative point of view. In this research we focus on the relation that exists, if any, between the type of approach to learning of the students and the academic results, distinguishing between deep and surface approaches. The sample is formed by students of Secondary Education from the academic course 2006-2007. Moreover, we have also observed the relation that could exist between the fact that a teacher teach them more than one subject and the obtained qualifications