Semistable rank 2 co-Higgs bundles over Hirzebruch surfaces

It has been observed by S. Rayan that the complex projective surfaces that potentially admit non-trivial examples of semistable co-Higgs bundles must be found at the lower end of the Enriques-Kodaira classification. Motivated by this remark, we study the geometry of these objects (in the rank 2 case) over Hirzebruch surfaces, giving special emphasis to P^1 x P^1. Two main topics can be identified throughout the dissertation: non-emptiness of the moduli spaces of rank 2 semistable co-Higgs bundles over Hirzebruch surfaces, and the description of these moduli spaces over P^1 x P^1. The existence problem consists in determining for which pairs of Chern classes (c_1; c_2) there exists a non-trivial semistable rank 2 co-Higgs bundle with Chern classes c_1 and c_2. We approach this problem from two different perspectives. On one hand, we restrict ourselves to certain natural choices of c_1 and give necessary and sufficient conditions on c_2 that guarantee the existence of non-trivial semistable co-Higgs bundles with these Chern classes; we do this for arbitrary polarizations when c_2 ≤ 2. On the other hand, for arbitrary c_1, we also provide necessary and sufficient conditions on c_2 that ensure the existence of nontrivial semistable co-Higgs bundles; however, we only do this for the standard polarization. As for the description of the moduli spaces M(c_1; c_2) of rank 2 semistable co-Higgs bundles over P^1 x P^1, we restrict ourselves to the standard polarization. We then discuss how to use the spectral construction and the Hitchin correspondence to understand generic rank 2 semistable co-Higgs bundles. Furthermore, we give an explicit description of the moduli spaces when c_2 = 0; 1 for certain choices of c_1. Finally, we explore the first order deformations of points in the moduli space M(c_1; c_2)

Dación en pago : análisis actual de la institución y antecedentes romanísticos

Treball Final de Grau en Dret. Codi: DR1052 Curs acadèmic: 2013-201

Addressing a forgotten struggle: Victims of enforced disappearance in Africa

Abstract: Enforced disappearance in Africa occurs on a daily basis and no one is immune from becoming a victim. The practice, which commenced during the colonial times, continues today. Governments routinely use enforced disappearance as a tool to oppress the opposition and instill fear among the population in order to retain power. It is also used in the context of migration, as well as in many other contexts and against a variety of victims. As enforced disappearance is a crime committed by State officials with an interest in concealing it, the statistics on its prevalence are limited and do not show the full extent of the crime in Africa. Further, the lack of political will to acknowledge the use of this practice means that many African States lack policies and laws to prevent, investigate and punish the perpetrators of enforced disappearance. In the last two years, the African Commission on Human and Peoples’ Rights adopted two resolutions raising awareness of the crime and paving the way for drafting and adopting specific guidelines to address this crime, which would be a first step in setting up a holistic framework to eradicate enforced disappearances on the continent

Resistance to the SDHI fungicides boscalid and fluopyram in Podosphaera xanthii from commercial cucurbit fields in Spain

Powdery mildew elicited by Podosphaera xanthii is a devastating disease of cucurbits worldwide and one of the most important diseases affecting these crops in Spain. Application of fungicides is the main control practice for managing P. xanthii; however, isolates resistant to multiple classes of site-specific fungicides have been recently reported in the Spanish cucurbit powdery mildew population. Succinate dehydrogenase inhibitors (SDHIs) constitute a relatively novel class of fungicides registered for powdery mildew control representing new alternatives for cucurbit growers. In the present study, 30 P. xanthii isolates were used to determine the effective concentration that reduces mycelial growth by 50% (EC50) to boscalid and fluopyram. The present study was also conducted to obtain discriminatory doses to monitor SDHI fungicide resistance in 180 P. xanthii isolates collected from several commercial cucurbit fields in Spain during 2017-2018. Three SDHI resistance patterns were observed in our population, which include patterns I (resistance to boscalid), II (resistance to fluopyram), and III (resistance to boscalid and fluopyram). The amino acid changes associated with these resistance patterns in the Sdh protein were also examined. Based on our results, SDHI fungicides are good alternatives for cucurbit powdery mildew control, although they should be applied with caution.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Resistance to SDHI fungicides in Botrytis cinerea from strawberry fields in Spain

Gray mold, caused by Botrytis cinerea Pers., is one of the most economically important diseases of strawberries and its control involves the application of fungicides throughout the strawberry growing season. Succinate dehydrogenase inhibitors (SDHIs) constitute a novel class of fungicides representing new alternatives for strawberry growers. In the present study, B. cinerea isolates were used to determine the effective concentration that reduces mycelial growth by 50% (EC50) and to obtain discriminatory doses to monitor SDHI fungicides over the course of three-year monitoring period. The overall frequencies of resistance to the SDHI fungicides boscalid, fluopyram, fluxapyroxad and penthiopyrad were 56.9, 6.9, 12.9, and 24.6%, respectively. Four SDHI resistance patterns were observed in our population. Patterns I (resistance to boscalid) and II (resistance to boscalid and penthiopyrad) were associated with the amino acid substitutions H272R/Y; pattern III (resistance to boscalid, fluxapyroxad, and penthiopyrad) was associated only with the H272Y mutation; and finally, pattern IV (resistance to boscalid, fluopyram, fluxapyroxad and penthiopyrad) was associated with the N230I allele in the SdhB subunit. For gray mold management, it is suggested that the simultaneous use of boscalid and penthiopyrad should be limited to one application per season. The use of fluxapyroxad and fluopyram could be used as valid SDHI alternatives for our strawberry growers, but they should be applied with caution.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The Limited Effect of Graphic Elements in Video and Augmented Reality on Children’s Listening Comprehension

There is currently significant interest in the use of instructional strategies in learning environments thanks to the emergence of new multimedia systems that combine text, audio, graphics and video, such as augmented reality (AR). In this light, this study compares the effectiveness of AR and video for listening comprehension tasks. The sample consisted of thirty-two elementary school students with different reading comprehension. Firstly, the experience, instructions and objectives were introduced to all the students. Next, they were divided into two groups to perform activities—one group performed an activity involving watching an Educational Video Story of the Laika dog and her Space Journey available by mobile devices app Blue Planet Tales, while the other performed an activity involving the use of AR, whose contents of the same history were visualized by means of the app Augment Sales. Once the activities were completed participants answered a comprehension test. Results (p = 0.180) indicate there are no meaningful differences between the lesson format and test performance. But there are differences between the participants of the AR group according to their reading comprehension level. With respect to the time taken to perform the comprehension test, there is no significant difference between the two groups but there is a difference between participants with a high and low level of comprehension. To conclude SUS (System Usability Scale) questionnaire was used to establish the measure usability for the AR app on a smartphone. An average score of 77.5 out of 100 was obtained in this questionnaire, which indicates that the app has fairly good user-centered design

Adaptación al español del instrumento sobre cultura organizacional de Denison

En este estudio se presentan los resultados de la adaptación a grupos I+D universitarios de habla hispana de la encuesta sobre cultura organizacional de Denison. Este cuestionario, compuesto por 60 ítems que identifican 12 tipos culturales, que a su vez se agrupan en cuatro dimensiones, ha demostrado su influencia para aumentar la efectividad organizacional. La adaptación al castellano que aquí se propone ha sido aplicada a 488 personas pertenecientes a 39 grupos de I+D tecnológicos de la Universidad Politécnica de Valencia. Los resultados obtenidos muestran unas propiedades psicométricas adecuadas para la adaptación realizada en cuanto a validez y fiabilidad, que replican casi en su totalidad la estructura del modelo de la versión original. This article presents a Spanish adaptation of Denison Organizational Culture Survey. This questionnaire consists of 60 items, grouped in 12 sub-scales, which identify 4 cultural dimensions. These dimensions have been widely study and their influence in organizational effectiveness is accepted. The Spanish adaptation proposed here has been applied in 488 participants of 39 I+D technological groups of Polytechnic University of Valencia. Results show adequate psychometric properties, so we can conclude that the Spanish adaptation almost fully replicates the structure of the original version in English

Política ambiental comunitaria en el desarrollo de políticas, planes y programas de infraestructuras de transporte

La política comunitaria se orienta hacia la conservación y mejora de la calidad del medio ambiente mediante una utilización prudente y racional de los recursos naturales, según el principio de cautela y con el objetivo de fomentar un desarrollo sostenible. La Evaluación Ambiental Estratégica (EAE) de Planes y Programas que tienen incidencia en el medio ambiente, constituye una de las herramientas más recientes con que las políticas comunitarias pretenden alcanzar los objetivos ambientales descritos. La Directiva 2001/42/CE precisa aplicar una EAE a los planes y programas de transporte, refrendada tanto por las orientaciones relativas a las Redes Transeuropeas de Transporte adoptadas en 1996, como por la reciente propuesta de modificación del 2001. Por ello, se requiere definir un marco metodológico de evaluación ambiental del Plan de Infraestructuras 2000-2007, que a su vez sirva de base para la EAE de futuros planes de infraestructuras de transporte en el contexto español y europeo

Effective multidimensional crossover behavior in a one-dimensional voter model with long-range probabilistic interactions

A variant of the standard voter model, where a randomly selected site of a one-dimensional lattice (d=1) adopts the state of another site placed at a distance r from the previous one, is proposed and studied by means of numerical simulations that are rationalized with the aid of dynamical and finite-size scaling arguments. The distance between the two sites is also selected randomly with a probability given by P(r)∝r-(d+σ), where σ is a control parameter. In this way one can study how the introduction of these long-range interactions influences the dynamic behavior of the standard voter model with nearest-neighbor interactions. It is found that the dynamics strongly depends on the range of the interactions, which is parameterized by σ, leading to an interesting effective multidimensional crossover behavior, as follows. (a) For σ2, as well as the case of both scale-free and small-world networks. (b) For σ>1, an ordering dynamics is observed, such that ρ(t)∝t-α, where the exponent α increases with σ until it reaches the value α=1/2 for σ⩾5, which corresponds to the behavior of the standard voter model with short-range interactions in d=1. (c) Finally, for σ≈1 we show evidence of a critical-type behavior as in the case of the critical dimension (dc=2) of the standard voter model.Fil: Rodriguez, Diego Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Bab, Marisa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Albano, Ezequiel Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentin