On the exhaustiveness of truncation and dropping strategies in many-to-many matching markets

We consider two–sided many–to–many matching markets in which each worker may work for multiple firms and each firm may hire multiple workers. We study individual and group manipulations in centralized markets that employ (pairwise) stable mechanisms and that require participants to submit rank order lists of agents on the other side of the market. We are interested in simple preference manipulations that have been reported and studied in empirical and theoretical work: truncation strategies, which are the lists obtained by removing a tail of least preferred partners from a preference list, and the more general dropping strategies, which are the lists obtained by only removing partners from a preference list (i.e., no reshuffling). We study when truncation / dropping strategies are exhaustive for a group of agents on the same side of the market, i.e., when each match resulting from preference manipulations can be replicated or improved upon by some truncation / dropping strategies. We prove that for each stable mechanism, truncation strategies are exhaustive for each agent with quota 1 (Theorem 1). We show that this result cannot be extended neither to group manipulations (even when all quotas equal 1 – Example 1), nor to individual manipulations when the agent’s quota is larger than 1 (even when all other agents’ quotas equal 1 – Example 2). Finally, we prove that for each stable mechanism, dropping strategies are exhaustive for each group of agents on the same side of the market (Theorem 2), i.e., independently of the quotas.

Análisis del constructo reflexividad-impulsividad : del Matching Familiar Figures Test (MFFT) al MFFT20.

Resumen tomado de la revista

Las becas y ayudas al estudio como elemento determinante de la continuidad escolar en el nivel secundario post-obligatorio : un análisis de sensibilidad a partir de la aplicación del Propensity Score Matching.

Resumen tomado de la publicación

Tree frogs.

La selva es el hogar de más de la mitad de los animales del mundo desde diminutos insectos a los grandes mamíferos pretende enseñar a los niños el ciclo de vida de las ranas arbóreas y la forma en que interactúan con su entorno, sus hábitos , su estilo de vida y las amenazas a los que se enfrenta por la actuación de los hombres al modificar las condiciones ambientales. La obra contiene un mapa de distribución de su hábitat, glosario y bibliografía.

Tree trogs.

Examina las características distintivas, ciclo de vida, la caza y la conducta de alimentación, hibernación, mecanismos de defensa de diferentes tipos de ranas de árboles. Incluye un glosario.

The dragon tree.

Pertenece a un amplio programa infantil de lectura que abarca distintos niveles de edad y, por tanto, de conocimientos. Se abordan las necesidades de lectura en los niños y la amplia variedad de habilidades que necesitan adquirir para su aprendizaje y, se destaca, también, la importancia de la narración en las historias. Los niños protagonistas viven una aventura fantástica con un dragón que vive en un árbol.

Sorting and matching.

Proporciona oportunidades para que los niños puedan practicar la clasificación y utilicen estas habilidades con una serie de objetos cotidianos, para desarrollar sus facultades de razonamiento y lógica. Las actividades animan a los niños a aprender a clasificar los elementos utilizando sus propios criterios y para investigar el uso dado a otros criterios como el color y tamaño utilizando sus diferentes sentidos.

Oxford reading tree. Teacher's guide 5 : robins and jackdaws stages 6-11.

Guía del profesor con recursos fotocopiables, para proporcionar más posibilidades a los niños con una capacidad por encima de la media y que pueden hacer frente a una mayor complejidad narrativa. Ofrece más de un género literario y un texto más maduro. Nuevas actividades, incluidas la comprensión, gramática, puntuación, y escritura creativa. Lista de libros para la lectura adicional.

Oxford reading tree. Teacher's guide 4 : woodpeckers : stages 3-9.

Da explicaciones detalladas para ayudar a los niños a aprender a leer en las primeras etapas. Facilita al profesor una serie de estrategias para la enseñanza de la lectura y una amplia variedad de recursos y materiales de apoyo linguístico. Contiene actividades de apoyo a una serie de estrategiás de lectura, recursos fotocopiables, actividades transversales de los contenidos curriculares, evaluación con hojas de registro. También incluye material adicional.

Oxford reading tree. Teacher's guide 3 : owls and magpies : stages 6-9.

Da explicaciones detalladas para ayudar a los niños a aprender a leer en las primeras etapas. Facilita al profesor una serie de estrategias para la enseñanza de la lectura y una amplia variedad de recursos y materiales de apoyo linguístico. Contiene actividades de apoyo a una serie de estrategiás de lectura, recursos fotocopiables, actividades transversales de los contenidos curriculares, evaluación con hojas de registro. También incluye material adicional.

Oxford reading tree. Teacher's guide 2 : stages 4-5.

Explicaciones detalladas de cómo sacar el máximo provecho de cada etapa. Las ideas y sugerencias de esta guía mantienen y amplían la filosofía de la lectura, y el programa, según la propuesta de métodos de enseñanza establecidos en la guía del primer nivel, que ayudarán a dar a los niños la confianza, y las habilidades necesarias para hacer frente a historias con textos más extensos y complejos. Contiene actividades de apoyo a una serie de estrategias de lectura, recursos fotocopiables, actividades tranversales de los contenidos curriculares, evaluación con hojas de registro. También incluye material adicional.

Oxford reading tree. Teacher's guide 1 : stages 1-3.

Explicaciones detalladas para ayudar a los niños a aprender a leer en las primeras etapas. Facilita al profesor una serie de estrategias para la enseñanza de la lectura y una amplia variedad de recursos y materiales de apoyo lingüístico. Contiene actividades de apoyo a una serie de estrategias de lectura, recursos fotocopiables, actividades transversales de los contenidos curriculares, evaluación con hojas de registro. También incluye material adicional.

Evaluaci??n del impacto de pol??ticas orientadas a la inserci??n sociolaboral mediante matching

Resumen basado en el de la publicaci??n

Irrigation performance and gross water productivity in furrow-irrigated ornamental tree production

In the ornamental plant production region of Girona (Spain), which is one of the largest of its kind in southern Europe, most of the surface is irrigated using wide blocked-end furrows. The objectives of this paper were: (1) to evaluate the irrigation scheduling methods used by ornamental plant producers; (2) to analyse different scenarios in order to assess how they affect irrigation performance; (3) to evaluate the risk of deep percolation; and (4) to calculate gross water productivity. A two-year study in a representative commercial field, planted with Prunus cerasifera ‘Nigra’, was carried out. The irrigation dose applied by the farmers was slightly smaller than the required water dose estimated by the use of two different methods: the first based on soil water content, and the second based on evapotranspiration. Distribution uniformity and application efficiency were high, with mean values above 87%. Soil water content measurements revealed that even at the end of the furrow, where the infiltrated water depth was greatest, more than 90% of the infiltrated water was retained in the shallowest 40 cm of the soil; accordingly, the risk of water loss due to deep percolation was minimal. Gross water productivity for ornamental tree production was € 11.70 m–3, approximately 20 times higher than that obtained with maize in the same region

Efficient topology estimation for large scale optical mapping

Large scale image mosaicing methods are in great demand among scientists who study different aspects of the seabed, and have been fostered by impressive advances in the capabilities of underwater robots in gathering optical data from the seafloor. Cost and weight constraints mean that lowcost Remotely operated vehicles (ROVs) usually have a very limited number of sensors. When a low-cost robot carries out a seafloor survey using a down-looking camera, it usually follows a predetermined trajectory that provides several non time-consecutive overlapping image pairs. Finding these pairs (a process known as topology estimation) is indispensable to obtaining globally consistent mosaics and accurate trajectory estimates, which are necessary for a global view of the surveyed area, especially when optical sensors are the only data source. This thesis presents a set of consistent methods aimed at creating large area image mosaics from optical data obtained during surveys with low-cost underwater vehicles. First, a global alignment method developed within a Feature-based image mosaicing (FIM) framework, where nonlinear minimisation is substituted by two linear steps, is discussed. Then, a simple four-point mosaic rectifying method is proposed to reduce distortions that might occur due to lens distortions, error accumulation and the difficulties of optical imaging in an underwater medium. The topology estimation problem is addressed by means of an augmented state and extended Kalman filter combined framework, aimed at minimising the total number of matching attempts and simultaneously obtaining the best possible trajectory. Potential image pairs are predicted by taking into account the uncertainty in the trajectory. The contribution of matching an image pair is investigated using information theory principles. Lastly, a different solution to the topology estimation problem is proposed in a bundle adjustment framework. Innovative aspects include the use of fast image similarity criterion combined with a Minimum spanning tree (MST) solution, to obtain a tentative topology. This topology is improved by attempting image matching with the pairs for which there is the most overlap evidence. Unlike previous approaches for large-area mosaicing, our framework is able to deal naturally with cases where time-consecutive images cannot be matched successfully, such as completely unordered sets. Finally, the efficiency of the proposed methods is discussed and a comparison made with other state-of-the-art approaches, using a series of challenging datasets in underwater scenarios