Sex-chromosome evolution of Palearctic tree frogs in space and time

Sexual reproduction is nearly universal in eukaryotes and genetic determination of sex prevails among animals. The astonishing diversity of sex-determining systems and sex chromosomes is yet bewildering. Some taxonomic groups possess conserved and dimorphic sex chromosomes, involving a functional copy (e.g. mammals' X, birds' Z) and a degenerated copy (mammals' Y, birds' W), implying that sex- chromosomes are expected to decay. In contrast, others like amphibians, reptiles and fishes yet maintained undifferentiated sex chromosomes. Why such different evolutionary trajectories? In this thesis, we empirically test and characterize the main hypotheses proposed to prevent the genetic decay of sex chromosomes, namely occasional X-Y recombination and frequent sex-chromosome transitions, using the Palearctic radiation of Hyla tree frogs as a model system. We take a phylogeographic and phylogenetic approach to relate sex-chromosome recombination, differentiation, and transitions in a spatial and temporal framework. By reconstructing the recent evolutionary history of the widespread European tree frog H. arborea, we showed that sex chromosomes can recombine in males, preventing their differentiation, a situation that potentially evolves rapidly. At the scale of the entire radiation, X-Y recombination combines with frequent transitions to prevent sex-chromosome degeneration in Hyla: we traced several turnovers of sex-determining system within the last 10My. These rapid changes seem less random than usually assumed: we gathered evidences that one chromosome pair is a sex expert, carrying genes with key role in animal sex determination, and which probably specialized through frequent reuse as a sex chromosome in Hyla and other amphibians. Finally, we took advantage of secondary contact zones between closely-related Hyla lineages to evaluate the consequences of sex chromosome homomorphy on the genetics of speciation. In comparison with other systems, the evolution of sex chromosomes in Hyla emphasized the existence of consistent evolutionary patterns within the chaotic diversity of flexibility of cold-blooded vertebrates' sex-determining systems, and provides insights into the evolution of recombination. Beyond sex-chromosome evolution, this work also significantly contributed to speciation, phylogeography and applied conservation research. -- La reproduction sexuée est quasi-universelle chez les eucaryotes et le sexe est le plus souvent déterminé génétiquement au sein du règne animal. L'incroyable diversité des systèmes de reproduction et des chromosomes sexuels est particulièrement étonnante. Certains groupes taxonomiques possèdent des chromosomes sexuels dimorphiques et très conservés, avec une copie entièrement fonctionnelle (ex : le X des mammifères, le Z des oiseaux) et une copie dégénérée (ex : le Y des mammifères, le W des oiseaux), suggérant que les chromosomes sexuels sont voués à se détériorer. Cependant les chromosomes sexuels d'autres groupes tels que les amphibiens, les reptiles et les poissons sont pour la plupart indifférenciés. Comment expliquer des trajectoires évolutives si différentes? Au cours de cette thèse, nous avons étudié empiriquement les processus évolutifs pouvant maintenir les chromosomes sexuels intacts, à savoir la recombinaison X-Y occasionnel ainsi que les substitutions fréquentes de chromosomes sexuels, en utilisant les rainettes Paléarctiques du genre Hyla comme modèle d'étude. Nous avons adopté une approche phylogéographique et phylogénétique pour appréhender les événements de recombinaison, de différenciation et de transitions de chromosomes sexuels dans un contexte spatio-temporel. En retraçant l'histoire évolutive récente de la rainette verte H. arborea, nous avons mis en évidence que les chromosomes sexuels pouvaient recombiner chez les mâles, empêchant ainsi leur différenciation, et que ce processus avait le potentiel d'évoluer très rapidement. A l'échelle plus globale de la radiation, il apparait que les phénomènes de recombinaison X-Y soient également accompagnés de substitutions de chromosomes sexuels, et participent de concert au maintien de chromosomes sexuels intacts dans les populations: le système de détermination du sexe des rainettes a changé plusieurs fois au cours des 10 derniers millions d'années. Ces transitions fréquentes ne semblent pas aléatoires: nous avons identifié une paire de chromosomes qui présente des caractéristiques présageant d'une spécialisation dans le déterminisme du sexe (notamment car elle possède des gènes importants pour cette fonction), et qui a été réutilisée plusieurs fois comme tel chez les rainettes ainsi que d'autres amphibiens. Enfin, nous avons étudié l'hybridation entre différentes espèces dans leurs zones de contact, afin d'évaluer si l'absence de différenciation entre X et Y jouaient un rôle dans les processus génétiques de spéciation. Outre son intérêt pour la compréhension de l'évolution des chromosomes sexuels, ce travail contribue de manière significative à d'autres domaines de recherche tels que la spéciation, la phylogéographie, ainsi que la biologie de la conservation.

Risk Factors for Incisional and Organ Space Surgical Site Infections After Liver Resection are Different.

BACKGROUND: Surgical site infection (SSI) is a common cause of major morbidity after liver resection. This study aimed to identify the risk factors for incisional and organ/space SSIs after liver resection. METHODS: Our liver surgery database was retrospectively analyzed for patients treated between January 2009 and November 2012 in a tertiary care Swiss hospital. Univariate and multivariate analyses were conducted on preoperative, intraoperative, and postoperative variables to identify risk factors for incisional and organ/space SSIs. RESULTS: In a total of 226 patients, SSI incidences were 12.8 % (incisional), 4.0 % (organ/space), and 1.8 % (both). Univariate analysis showed that incisional SSIs were associated with high American Society of Anesthesiologists (ASA) scores, preoperative anemia, hypoalbuminemia, low prothrombin time, viral or alcoholic chronic hepatitis, liver cirrhosis, and prolonged operation times. Organ/space SSIs were associated with high rates of red blood cell transfusions, concomitant bowel surgery, and prolonged operation times. Multivariate analysis revealed that risk factors for incisional SSIs were anemia [odds ratio (OR) 2.82], high ASA scores (OR 2.88), presence of hepatitis or cirrhosis (OR 5.07), and prolonged operation times (OR 9.61). The only risk factor for organ/space SSIs was concomitant bowel surgery (OR 5.53). Hospital stays were similar in organ/space and incisional SSI groups, but significantly longer for those with both organ/space and incisional SSIs. CONCLUSIONS: High ASA scores, anemia, chronic hepatitis or liver cirrhosis, and prolonged operations increased the risk of incisional SSIs; concomitant bowel surgery increased the risk of organ/space SSI. Specific precautions to prevent organ/space and incisional SSIs may shorten hospital stays.

Definition of linear color models in the RGB vector color space to detect red peaches in orchard images taken under natural illumination

This work proposes the detection of red peaches in orchard images based on the definition of different linear color models in the RGB vector color space. The classification and segmentation of the pixels of the image is then performed by comparing the color distance from each pixel to the different previously defined linear color models. The methodology proposed has been tested with images obtained in a real orchard under natural light. The peach variety in the orchard was the paraguayo (Prunus persica var. platycarpa) peach with red skin. The segmentation results showed that the area of the red peaches in the images was detected with an average error of 11.6%; 19.7% in the case of bright illumination; 8.2% in the case of low illumination; 8.6% for occlusion up to 33%; 12.2% in the case of occlusion between 34 and 66%; and 23% for occlusion above 66%. Finally, a methodology was proposed to estimate the diameter of the fruits based on an ellipsoidal fitting. A first diameter was obtained by using all the contour pixels and a second diameter was obtained by rejecting some pixels of the contour. This approach enables a rough estimate of the fruit occlusion percentage range by comparing the two diameter estimates.

Wiki-supported collaborative learning in primary education. How a dialogic space is created for thinking together

This paper explores how wikis may be used to support primary education students’ collaborative interaction and how such an interaction process can be characterised. The overall aim of this study is to analyse the collaborative processes of students working together in a wiki environment, in order to see how primary students can actively create a shared context for learning in the wiki. Educational literature has already reported that wikis may support collaborative knowledge-construction processes, but in our study we claim that a dialogic perspective is needed to accomplish this. Students must develop an intersubjective orientation towards each others’ perspectives, to co-construct knowledge about a topic. For this purpose, our project utilised a ‘Thinking Together’ approach to help students develop an intersubjective orientation towards one another and to support the creation of a ‘dialogic space’ to co-construct new understanding in a wiki science project. The students’ asynchronous interaction process in a primary classroom -- which led to the creation of a science text in the wiki -- was analysed and characterised, using a dialogic approach to the study of CSCL practices. Our results illustrate how the Thinking Together approach became embedded within the wiki environment and in the students’ collaborative processes. We argue that a dialogic approach for examining interaction can be used to help design more effective pedagogic approaches related to the use of wikis in education and to equip learners with the competences they need to participate in the global knowledge-construction era.

Utilidad de un fórum virtual para realizar trabajos colaborativos con presentación individual evaluable

Objetivos. Valorar la utilidad de un fórum virtual sobre la discusión de un caso clínico por grupos para la presentación de un trabajo individual. Material y métodos. En uno de los seminarios de la asignatura Enfermedades del Aparato Respiratorio y ORL del grado de Medicina, se creó un fórum virtual para discutir un caso clínico por grupos, antes de presentar un trabajo individual. Se realizaron cuatro grupos (A, B, C y D) y se abrieron cuatro temas. Cada grupo sólo podía participar en uno, pero tenían que observar la evolución de los otros foros. El trabajo individual consistía en contestar a varias preguntas planteadas por el profesor relacionadas con el desarrollo del caso clínico virtual. Para analizar los resultados de la experiencia se valoró: el número de participaciones en el foro, el número de participaciones por grupo, la nota del trabajo individual y la opinión del profesor Resultados. Se realizaron 129 participaciones al foro. El grupo A fue el que más participó (27%). El 78% de los alumnos obtuvo una nota comprendida entre el 7 y el 9. Del análisis cualitativo del trabajo individual se observó que los alumnos contestaban correctamente las preguntas, pero no se basaban en lo que sus compañeros habían desarrollado en el foro. Conclusiones. Los foros virtuales basados en la discusión de casos clínicos pueden facilitar el aprendizaje colaborativo en alumnos del grado de Medicina.

Efectividad del trabajo de doble tarea cognitivo-motora con incorporación de realidad virtual para el tratamiento del equilibrio en pacientes con Traumatismo Craneoencefálico.

Pregunta de revisión: ¿El tratamiento de doble tarea con la incorporación del sistema de realidad virtual BioTrack favorece el equilibrio en los pacientes que han sufrido un traumatismo craneoencefálico? Objetivo: Determinar si el trabajo de doble tarea cognitivo-motor con la incorporación de realidad virtual favorece el equilibrio de los pacientes con traumatismo craneoencefálico. Metodología: se realizará un diseño de tipo experimental, aleatorio controlado y prospectivo. Se planteará un proyecto de 36 sesiones dividido en seis meses basado en trabajo de doble tarea cognitivo-motor con realidad virtual. Consta de un tratamiento combinado de ejercicios para el equilibrio con el soporte de realidad virtual BioTrack. Al mismo tiempo se trabajará la memoria y la atención para el trabajo cognitivo. Se compara con el grupo control que solo realiza ejercicios con BioTrack. La medida principal es el equilibrio medido con la berg balance scale y la influencia del trabajo cognitivo.

El nou web de la Biblioteca Virtual de la UOC: Jornada Tècnica

Presentació del projecte de disseny i desenvolupament del nou web de la Biblioteca Virtual, a la Jornada Tècnica de UOC.

Customization, transparency and proximity: a user- centered content strategy applied to the design of a virtual library website

We present a case study of the redesign of the organizational presentation and content of the Virtual Library website at the Universitat Oberta de Catalunya (Open University of Catalonia, UOC), based on a user-centered design strategy. The aim of the redesign was to provide users with more intuitive, usable and understandable content (textual content, resources and services) by implementing criteria of customization, transparency and proximity. The study also presents a selection of best practices for applying these criteria to the design of other library websites.

How to redesign a virtual library website: a case study

This abstract presents how we redesigned, with user-centred design methods, the way we organize and present the content on the UOC Virtual Library website. The content is now offered in a way that is more intuitive, usable and easy to understand, based on criteria of customization, transparency and proximity.The techniques used to achieve these objectives included benchmarking, interviews and focus groups during the user requirement capture phase and user tests to assess the process and results.

An Analysis of Eye Scanpath Entropy in a Progressively Forming Virtual Environment

A sign of presence in virtual environments is that people respond to situations and events as if they were real, where response may be considered at many different levels, ranging from unconscious physiological responses through to overt behavior,emotions, and thoughts. In this paper we consider two responses that gave different indications of the onset of presence in a gradually forming environment. Two aspects of the response of people to an immersive virtual environment were recorded: their eye scanpath, and their skin conductance response (SCR). The scenario was formed over a period of 2 min, by introducing an increasing number of its polygons in random order in a head-tracked head-mounted display. For one group of experimental participants (n 8) the environment formed into one in which they found themselves standing on top of a 3 m high column. For a second group of participants (n 6) the environment was otherwise the same except that the column was only 1 cm high, so that they would be standing at normal ground level. For a third group of participants (n 14) the polygons never formed into a meaningful environment. The participants who stood on top of the tall column exhibited a significant decrease in entropy of the eye scanpath and an increase in the number of SCR by 99 s into the scenario, at a time when only 65% of the polygons had been displayed. The ground level participants exhibited a similar decrease in scanpath entropy, but not the increase in SCR. The random scenario grouping did not exhibit this decrease in eye scanpath entropy. A drop in scanpath entropy indicates that the environment had cohered into a meaningful perception. An increase in the rate of SCR indicates the perception of an aversive stimulus. These results suggest that on these two dimensions (scanpath entropy and rate of SCR) participants were responding realistically to the scenario shown in the virtual environment. In addition, the response occurred well before the entire scenario had been displayed, suggesting that once a set of minimal cues exists within a scenario,it is enough to form a meaningful perception. Moreover, at the level of the sympathetic nervous system, the participants who were standing on top of the column exhibited arousal as if their experience might be real. This is an important practical aspect of the concept of presence.

Nou web de la Biblioteca Virtual: anàlisi del nou web de la Biblioteca de la UOC

Informe de l'anàlisi realitzat sobre el nou web de la Biblioteca Virtual de la UOC, mitjançant el mètode de test amb usuaris, per tal d'avaluar el grau d'usabilitat de la nova eina. L'anàlisi s'emmarca en el procés de disseny centrat en l'usuari que s'ha utilitzat per al seu disseny.

Nou web de la Biblioteca Virtual: test amb usuaris, desembre 2013

Informe de l'anàlisi realitzat sobre el nou web de la Biblioteca Virtual de la UOC, per tal d'avaluar el grau d'usabilitat de la nova eina. És el segon test amb usuaris que es realitza del nou web i s'han analitzat els següents aspectes: l'accés a la col·lecció digital, les cinc funcionalitats més utilitzades del web i les cinc funcionalitats menys visibles del web.

The Impact of a Character Posture Model on the Communication of Affect in an Immersive Virtual Environment

This paper presents the quantitative and qualitative findings from an experiment designed to evaluate a developing model of affective postures for full-body virtual characters in immersive virtual environments (IVEs). Forty-nine participants were each requested to explore a virtual environment by asking two virtual characters for instructions. The participants used a CAVE-like system to explore the environment. Participant responses and their impression of the virtual characters were evaluated through a wide variety of both quantitative and qualitative methods. Combining a controlled experimental approach with various data-collection methods provided a number of advantages such as providing a reason to the quantitative results. The quantitative results indicate that posture plays an important role in the communication of affect by virtual characters. The qualitative findings indicated that participants attribute a variety of psychological states to the behavioral cues displayed by virtual characters. In addition, participants tended to interpret the social context portrayed by the virtual characters in a holistic manner. This suggests that one aspect of the virtual scene colors the perception of the whole social context portrayed by the virtual characters. We conclude by discussing the importance of designing holistically congruent virtual characters especially in immersive settings.

Diagnosis of the nutrient compositional space of fruit crops

Tissue analysis is a useful tool for the nutrient management of fruit orchards. The mineral composition of diagnostic tissues expressed as nutrient concentration on a dry weight basis has long been used to assess the status of 'pure' nutrients. When nutrients are mixed and interact in plant tissues, their proportions or concentrations change relatively to each other as a result of synergism, antagonism, or neutrality, hence producing resonance within the closed space of tissue composition. Ternary diagrams and nutrient ratios are early representations of interacting nutrients in the compositional space. Dual and multiple interactions were integrated by the Diagnosis and Recommendation Integrated System (DRIS) into nutrient indexes and by Compositional Nutrient Diagnosis into centered log ratios (CND-clr). DRIS has some computational flaws such as using a dry matter index that is not a part as well as nutrient products (e.g. NxCa) instead of ratios. DRIS and CND-clr integrate all possible nutrient interactions without defining an ad hoc interactive model. They diagnose D components while D-1 could be diagnosed in the D-compositional Hilbert space. The isometric log ratio (ilr) coordinates overcome these problems using orthonormal binary nutrient partitions instead of dual ratios. In this study, it is presented a nutrient interactive model as well as computation methods for DRIS and CND-clr and CND-ilr coordinates (CND-ilr) using leaf analytical data from an experimental apple orchard in Southwestern Quebec, Canada. It was computed the Aitchison and Mahalanobis distances across ilr coordinates as measures of nutrient imbalance. The effect of changing nutrient concentrations on ilr coordinates are simulated to identify the ones contributing the most to nutrient imbalance.

From room for books to room for users: an old infantry barrack as an answer to the lack of space

At the beginning of the 21st century, some Catalan university libraries detected a need stemming from the lack of space and the reconversion of physical libraries within the new European educational panorama. With the same cooperative spirit that characterized previous CBUC (Consortium of Academic Libraries of Catalonia) programs and services, the Consortium set in motion a project to address this need. An initial study was commissioned in 2002, and in 2003 a suitable building (old infantry barracks) was found in Lleida. The official opening took place in 2008. GEPA (Guaranteed Space for the Preservation of Access) facility is a cooperative repository, whose objectives are to store and preserve low use documents, ensuring their future access when needed, to convert room for books into room for library users, and doing it saving both space and money. The paper presents a brief historical introduction about the physical management of collections in libraries, and a short overview about high density library repositories all over the world, as an answer to the pressing problem of lack of spaces. The main goals of the communication are to comment the architectural project and its librarian issues, and to show how the GEPA facility allowed to change the spaces in university libraries in Catalonia. On the one hand, the paper deals with the selection of an old building to be renovated, the determination of the librarian needs, the compact shelving system chosen to store the documents in the building, the relation between physical space and information management, and the logistics involved in the load of low use documents from the libraries into the facility. On the other hand, we will show some examples of physical changes in Catalan libraries after large loads of documents to GEPA.