982 resultados para he Johansen Co-integration


Relevância:

30.00% 30.00%

Publicador:

Resumo:

The integration of academic and non-academic knowledge is a key concern for researchers who aim at bridging the gap between research and policy. Researchers involved in the sustainability-oriented NCCR North-South programme have made the experience that linking different types of knowledge requires time and effort, and that methodologies are still lacking. One programme component was created at the inception of this transdisciplinary research programme to support exchange between researchers, development practitioners and policymakers. After 8 years of research, the programme is assessing whether research has indeed enabled a continuous communication across and beyond academic boundaries and has effected changes in the public policies of poor countries. In a first review of the data, we selected two case studies explicitly addressing the lives of women. In both cases – one in Pakistan, the other in Nepal – the dialogue between researchers and development practitioners contributed to important policy changes for female migration. In both countries, outmigration has become an increasingly important livelihood strategy. National migration policies are gendered, limiting the international migration of women. In Nepal, women were not allowed to migrate to specific countries such as the Gulf States or Malaysia. This was done in the name of positive discrimination, to protect women from potential exploitation and harassment in domestic work. However, women continued to migrate in many other and often illegal and more risky ways, increasing their vulnerability. In Pakistan, female labour migration was not allowed at all and male migration increased the vulnerability of the families remaining back home. Researchers and development practitioners in Nepal and Pakistan brought women’s shared experience of and exposure to the mechanisms of male domination into the public debate, and addressed the discriminating laws. Now, for the first time in Pakistan, the new draft policy currently under discussion would enable broadly-based female labour migration. What can we learn from the two case studies with regard to ways of relating experience- and research-based knowledge? The paper offers insights into the sequence of interactions between researchers, local people, development practitioners, and policy-makers, which eventually contributed to the formulation of a rights-based migration policy. The reflection aims at exploring the gendered dimension of ways to co-produce and share knowledge for development across boundaries. Above all, it should help researchers to better tighten the links between the spheres of research and policy in future.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Ausgehend von der typischen IT‐Infrastruktur für E‐Learning an Hochschulen auf der einen Seite sowie vom bisherigen Stand der Forschung zu Personal Learning Environments (PLEs) auf der anderen Seite zeigt dieser Beitrag auf, wie bestehende Werkzeuge bzw. Dienste zusammengeführt und für die Anforderungen der modernen, rechnergestützten Präsenzlehre aufbereitet werden können. Für diesen interdisziplinären Entwicklungsprozess bieten sowohl klassische Softwareentwicklungsverfahren als auch bestehende PLE‐Modelle wenig Hilfestellung an. Der Beitrag beschreibt die in einem campusweiten Projekt an der Universität Potsdam verfolgten Ansätze und die damit erzielten Ergebnisse. Dafür werden zunächst typische Lehr‐/Lern‐bzw. Kommunikations‐Szenarien identifiziert, aus denen Anforderungen an eine unterstützende Plattform abgeleitet werden. Dies führt zu einer umfassenden Sammlung zu berücksichtigender Dienste und deren Funktionen, die gemäß den Spezifika ihrer Nutzung in ein Gesamtsystem zu integrieren sind. Auf dieser Basis werden grundsätzliche Integrationsansätze und technische Details dieses Mash‐Ups in einer Gesamtschau aller relevanten Dienste betrachtet und in eine integrierende Systemarchitektur überführt. Deren konkrete Realisierung mit Hilfe der Portal‐Technologie Liferay wird dargestellt, wobei die eingangs definierten Szenarien aufgegriffen und exemplarisch vorgestellt werden. Ergänzende Anpassungen im Sinne einer personalisierbaren bzw. adaptiven Lern‐(und Arbeits‐)Umgebung werden ebenfalls unterstützt und kurz aufgezeigt.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In Europe and North America, migration and integration has become a busy subfield of political sociology. Of particular interest in this respect is the integration of Muslims and Islam, which has dominated the debate in Europe. Broadly conceived «political opportunity structures» have received much attention in this context. But the role of liberal law in the integration of Islam has been largely ignored, not by lawyers of course, but by political sociologists who have thus delivered far too negative and truncated pictures of Muslims and Islam in Europe. This is the deficit we sought to redress in Legal Integration of Islam; A Transatlantic Comparison (2013) (co-authored with John Torpey). Some of this study’s main ideas and findings are presented in the following.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

BACKGROUND Implementation of user-friendly, real-time, electronic medical records for patient management may lead to improved adherence to clinical guidelines and improved quality of patient care. We detail the systematic, iterative process that implementation partners, Lighthouse clinic and Baobab Health Trust, employed to develop and implement a point-of-care electronic medical records system in an integrated, public clinic in Malawi that serves HIV-infected and tuberculosis (TB) patients. METHODS Baobab Health Trust, the system developers, conducted a series of technical and clinical meetings with Lighthouse and Ministry of Health to determine specifications. Multiple pre-testing sessions assessed patient flow, question clarity, information sequencing, and verified compliance to national guidelines. Final components of the TB/HIV electronic medical records system include: patient demographics; anthropometric measurements; laboratory samples and results; HIV testing; WHO clinical staging; TB diagnosis; family planning; clinical review; and drug dispensing. RESULTS Our experience suggests that an electronic medical records system can improve patient management, enhance integration of TB/HIV services, and improve provider decision-making. However, despite sufficient funding and motivation, several challenges delayed system launch including: expansion of system components to include of HIV testing and counseling services; changes in the national antiretroviral treatment guidelines that required system revision; and low confidence to use the system among new healthcare workers. To ensure a more robust and agile system that met all stakeholder and user needs, our electronic medical records launch was delayed more than a year. Open communication with stakeholders, careful consideration of ongoing provider input, and a well-functioning, backup, paper-based TB registry helped ensure successful implementation and sustainability of the system. Additional, on-site, technical support provided reassurance and swift problem-solving during the extended launch period. CONCLUSION Even when system users are closely involved in the design and development of an electronic medical record system, it is critical to allow sufficient time for software development, solicitation of detailed feedback from both users and stakeholders, and iterative system revisions to successfully transition from paper to point-of-care electronic medical records. For those in low-resource settings, electronic medical records for integrated care is a possible and positive innovation.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Objective: The present study offers a novel methodological contribution to the study of the configuration and dynamics of research groups, through a comparative perspective of the projects funded (inputs) and publication co-authorships (output). Method: A combination of bibliometric techniques and social network analysis was applied to a case study: the Departmento de Bibliotecología (DHUBI), Universidad Nacional de La Plata, Argentina, for the period 2000-2009. The results were interpreted statistically and staff members of the department, were interviewed. Results: The method makes it possible to distinguish groups, identify their members and reflect group make-up through an analytical strategy that involves the categorization of actors and the interdisciplinary and national or international projection of the networks that they configure. The integration of these two aspects (input and output) at different points in time over the analyzed period leads to inferences about group profiles and the roles of actors. Conclusions: The methodology presented is conducive to micro-level interpretations in a given area of study, regarding individual researchers or research groups. Because the comparative input-output analysis broadens the base of information and makes it possible to follow up, over time, individual and group trends, it may prove very useful for the management, promotion and evaluation of science

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Objective: The present study offers a novel methodological contribution to the study of the configuration and dynamics of research groups, through a comparative perspective of the projects funded (inputs) and publication co-authorships (output). Method: A combination of bibliometric techniques and social network analysis was applied to a case study: the Departmento de Bibliotecología (DHUBI), Universidad Nacional de La Plata, Argentina, for the period 2000-2009. The results were interpreted statistically and staff members of the department, were interviewed. Results: The method makes it possible to distinguish groups, identify their members and reflect group make-up through an analytical strategy that involves the categorization of actors and the interdisciplinary and national or international projection of the networks that they configure. The integration of these two aspects (input and output) at different points in time over the analyzed period leads to inferences about group profiles and the roles of actors. Conclusions: The methodology presented is conducive to micro-level interpretations in a given area of study, regarding individual researchers or research groups. Because the comparative input-output analysis broadens the base of information and makes it possible to follow up, over time, individual and group trends, it may prove very useful for the management, promotion and evaluation of science

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Objective: The present study offers a novel methodological contribution to the study of the configuration and dynamics of research groups, through a comparative perspective of the projects funded (inputs) and publication co-authorships (output). Method: A combination of bibliometric techniques and social network analysis was applied to a case study: the Departmento de Bibliotecología (DHUBI), Universidad Nacional de La Plata, Argentina, for the period 2000-2009. The results were interpreted statistically and staff members of the department, were interviewed. Results: The method makes it possible to distinguish groups, identify their members and reflect group make-up through an analytical strategy that involves the categorization of actors and the interdisciplinary and national or international projection of the networks that they configure. The integration of these two aspects (input and output) at different points in time over the analyzed period leads to inferences about group profiles and the roles of actors. Conclusions: The methodology presented is conducive to micro-level interpretations in a given area of study, regarding individual researchers or research groups. Because the comparative input-output analysis broadens the base of information and makes it possible to follow up, over time, individual and group trends, it may prove very useful for the management, promotion and evaluation of science

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Ever since the handover of the territory in 1997, Hong Kong has had its own unique law and its own economic system and international legal personality, and has not been integrated with Mainland China. The Basic Law guarantees the uniqueness of the Hong Kong SAR until 2047. But close economic ties between Hong Kong and the Mainland will promote closer economic integration. The Basic Law limits only a customs union and the introduction of a single currency, but not the formation of a Free Trade Agreement (hereafter FTA) and monetary union. FTA has already been realized in the form of the Closer Economic Partnership Arrangement (hereafter CEPA). The Hong Kong SAR government, including the bureaucrat as well as the Chief Executive Tung Chee Hwa, was opposed to, and hesitant towards, the formation of a regional trade agreement with the Mainland, but the business community made them to adopt a positive attitude towards the CEPA. It is unclear how much integration can been deepened, but it can be argued that the current policy of the Hong Kong SAR is too supportive of business, and an excessive degree of economic integration may threaten the uniqueness of Hong Kong. But if Hong Kong achieves democracy and enjoys complete autonomy, it will be easy for economic integration to co-exist with the 'One Country, Two Systems' approach, in the interests of the business community and of the citizens of the SAR.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Embedded systems are commonly designed by specifying and developing hardware and software systems separately. On the contrary, the hardware/software (HW/SW) co-development exploits the trade-offs between hardware and software in a system through their concurrent design. HW/SW Codevelopment techniques take advantage of the flexibility of system design to create architectures that can meet stringent performance requirements with a shorter design cycle. This paper presents the work done within the scope of ESA HWSWCO (Hardware-Software Co-design) study. The main objective of this study has been to address the HW/SW co-design phase to integrate this engineering task as part of the ASSERT process (refer to [1]) and compatible with the existing ASSERT approach, process and tool, Advances in the automation of the design of HW and SW and the adoption of the Model Driven Architecture (MDA) [9] paradigm make possible the definition of a proper integration substrate and enables the continuous interaction of the HW and SW design paths.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Abstract. The ASSERT project de?ned new software engineering methods and tools for the development of critical embedded real-time systems in the space domain. The ASSERT model-driven engineering process was one of the achievements of the project and is based on the concept of property- preserving model transformations. The key element of this process is that non-functional properties of the software system must be preserved during model transformations. Properties preservation is carried out through model transformations compliant with the Ravenscar Pro?le and provides a formal basis to the process. In this way, the so-called Ravenscar Computational Model is central to the whole ASSERT process. This paper describes the work done in the HWSWCO study, whose main objective has been to address the integration of the Hardware/Software co-design phase in the ASSERT process. In order to do that, non-functional properties of the software system must also be preserved during hardware synthesis. Keywords : Ada 2005, Ravenscar pro?le, Hardware/Software co-design, real- time systems, high-integrity systems, ORK

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Esta tesis doctoral está enmarcada en dos diferentes pero complementarias áreas de investigación: las redes de Publicación/Subscripción y los servicios móviles distribuidos. Con el paso de los años las redes de Publicación/Subscripción han ido ofreciendo el soporte de comunicaciones desacopladas y ligeras que a su vez, han mejorado la distribución de la información en muchos escenarios de aplicación como lo son la ejecución de servicios distribuidos en entornos fijos. Los servicios móviles distribuidos han de ser desplegados en ambientes inalámbricos en donde los dispositivos móviles deben confiar en las mismas características que las redes de Publicación/Subscripción han estado ofreciendo a sus contrapartes fijos. En este contexto, una de las líneas de investigación pendientes consiste en cómo tomar ventaja de estas características, y cómo avanzar hacia nuevas soluciones no existentes con el fin de mejorar la integración entre los dispositivos fijos y móviles, y la ejecución de los servicios móviles distribuidos. En esta tesis doctoral se pretende avanzar en los mecanismos de integración y coordinación de los servicios móviles distribuidos en el contexto de las redes de Publicación/Subscripción. Los objetivos específicos de esta disertación están enfocados en lograr la integración de los sistemas de Publicación/Suscripción fijos y móviles, y la pro-visión de una versión de red de Publicación/Subscripción específica y uniforme que cuente con mecanismos de coordinación que mejoren la ejecución de los servicios móviles distribuidos. Los resultados de esta tesis doctoral están enmarcados en una versión específica de una red de Publicación/Subscripción que integra brokers fijos y móviles, y permite una coordinación totalmente desacoplada y mejorada entre dispositivos móviles que ejecutan fragmentos de servicios. Las contribuciones específicas son las siguientes: una nueva arquitectura de broker móvil que he llamado Rendezvous Mobile broker, un modelo abstracto de servicios móviles distribuidos coordinados sobre una red de Publicación/Subscripción, mejoras en los mecanismos de enrutamiento epidémicos para diseminar eventos de control producidos por fragmentos de servicios, una solución para soportar servicios altamente fragmentados y geográficamente dispersos, y finalmente una solución de interconexión entre dos dominios de red basados en Publicación/Subscripción: una red basada en el protocolo PubSubHubbub y otro en una red basada en el Publish/Subscribe Internet Routing Paradigm (PSIRP). Los experimentos llevados a cabo confirman que la versión específica de red de Pu-blicación/Subscripción propuesta incrementa el rendimiento de la red en términos de tiempo de espera entre nodos finales, permite una coordinación de los servicios móviles distribuidos más resistente a interrupciones y un mejor uso de los recursos de red, y finalmente logra exitosamente, con variaciones mínimas en el rendimiento de las comunicaciones, la interconexión entre estos dominios de Publicación/Subscripción diferentes. ABSTRACT This dissertation is made up of two different but complementary research areas: Publish/Subscribe networks and mobile distributed services. Over the years, Publish/Subscribe networks have been offering the lightweight and decoupled communication characteristics to improve the information distribution in several application domains such as the execution of distributed services. Mobile distributed services are set to be deployed in wireless environments where mobile devices must rely on the same features Publish/Subscribe networks can offer; so one of the pending research directions consists of how to take advantage of these features and further advance to-wards new un-existing solutions that enhance the integration between mobile and fixed systems and the execution of mobile distributed services. This dissertation seeks to advance the integration and coordination mechanisms of mobile distributed services in the context of Publish/Subscribe networks. The specific objectives aim to enable the integration of mobile and fixed Publish/Subscribe systems and provide a uniform and specific version of a Publish/Subscribe network with new coordination mechanisms that improve the execution of mobile distributed services. The results of this dissertation are enclosed in one specific version of a Publish/Subscribe network that integrates mobile and fixed brokers and coordinates the execution of mobile distributed services. These specific contributions are: a new architecture of a mobile broker I called Rendezvous Mobile Broker, an abstract model for coordinating mobile distributed services executions using a Publish/Subscribe net-work, new gossip routing solutions to disseminate events of services, mechanisms to support highly partitioned and geographically dispersed services and finally, an inter-networking solution between two Publish/Subscribe domains: a PubSubHubbub-based network and the Publish/Subscribe Internet Routing Paradigm (PSIRP)-based network. The experimental efforts confirm that the specific version of the Publish/Subscribe proposed in this dissertation improves the performance of the overall network in terms of end-to-end delay, enables a more resilience execution of mobile distributed services, a better usage of the existing network resources, and finally successfully achieves, with minor variations in the network performance, the internetworking between two different Publish/Subscribe domains.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Actualmente, la gestión de sistemas de Manejo Integrado de Plagas (MIP) en cultivos hortícolas tiene por objetivo priorizar los métodos de control no químicos en detrimento del consumo de plaguicidas, según recoge la directiva europea 2009/128/CE ‘Uso Sostenible de Plaguicidas’ (OJEC, 2009). El uso de agentes de biocontrol como alternativa a la aplicación de insecticidas es un elemento clave de los sistemas MIP por sus innegables ventajas ambientales que se utiliza ampliamente en nuestro país (Jacas y Urbaneja, 2008). En la región de Almería, donde se concentra el 65% de cultivo en invernadero de nuestro país (47.367 ha), MIP es la principal estrategia en pimiento (MAGRAMA, 2014), y comienza a serlo en otros cultivos como tomate o pepino. El cultivo de pepino, con 8.902 ha (MAGRAMA, 2013), tiene un protocolo semejante al pimiento (Robledo et al., 2009), donde la única especie de pulgón importante es Aphis gossypii Glover. Sin embargo, pese al continuo incremento de la superficie de cultivo agrícola bajo sistemas MIP, los daños originados por virosis siguen siendo notables. Algunos de los insectos presentes en los cultivos de hortícolas son importantes vectores de virus, como los pulgones, las moscas blancas o los trips, cuyo control resulta problemático debido a su elevada capacidad para transmitir virus vegetales incluso a una baja densidad de plaga (Holt et al., 2008; Jacas y Urbaneja, 2008). Las relaciones que se establecen entre los distintos agentes de un ecosistema son complejas y muy específicas. Se ha comprobado que, pese a que los enemigos naturales reducen de manera beneficiosa los niveles de plaga, su incorporación en los sistemas planta-insecto-virus puede desencadenar complicadas interacciones con efectos no deseables (Dicke y van Loon, 2000; Jeger et al., 2011). Así, los agentes de biocontrol también pueden inducir a que los insectos vectores modifiquen su comportamiento como respuesta al ataque y, con ello, el grado de dispersión y los patrones de distribución de las virosis que transmiten (Bailey et al., 1995; Weber et al., 1996; Hodge y Powell, 2008a; Hodge et al., 2011). Además, en ocasiones el control biológico por sí solo no es suficiente para controlar determinadas plagas (Medina et al., 2008). Entre los métodos que se pueden aplicar bajo sistemas MIP están las barreras físicas que limitan la entrada de plagas al interior de los invernaderos o interfieren con su movimiento, como pueden ser las mallas anti-insecto (Álvarez et al., 2014), las mallas fotoselectivas (Raviv y Antignus, 2004; Weintraub y Berlinger, 2004; Díaz y Fereres, 2007) y las mallas impregnadas en insecticida (Licciardi et al., 2008; Martin et al., 2014). Las mallas fotoselectivas reducen o bloquean casi por completo la transmisión de radiación UV, lo que interfiere con la visión de los insectos y dificulta o impide la localización del cultivo y su establecimiento en el mismo (Raviv y Antignus, 2004; Weintraub, 2009). Se ha comprobado cómo su uso puede controlar los pulgones y las virosis en cultivo de lechuga (Díaz et al., 2006; Legarrea et al., 2012a), así como la mosca blanca, los trips y los ácaros, y los virus que estos transmiten en otros cultivos (Costa y Robb, 1999; Antignus et al., 2001; Kumar y Poehling, 2006; Doukas y Payne, 2007a; Legarrea et al., 2010). Sin embargo, no se conoce perfectamente el modo de acción de estas barreras, puesto que existe un efecto directo sobre la plaga y otro indirecto mediado por la planta, cuya fisiología cambia al desarrollarse en ambientes con falta de radiación UV, y que podría afectar al ciclo biológico de los insectos fitófagos (Vänninen et al., 2010; Johansen et al., 2011). Del mismo modo, es necesario estudiar la compatibilidad de esta estrategia con los enemigos naturales de las plagas. Hasta la fecha, los estudios han evidenciado que los agentes de biocontrol pueden realizar su actividad bajo ambientes pobres en radiación UV (Chyzik et al., 2003; Chiel et al., 2006; Doukas y Payne, 2007b; Legarrea et al., 2012c). Otro método basado en barreras físicas son las mallas impregnadas con insecticidas, que se han usado tradicionalmente en la prevención de enfermedades humanas transmitidas por mosquitos (Martin et al., 2006). Su aplicación se ha ensayado en agricultura en ciertos cultivos al aire libre (Martin et al., 2010; Díaz et al., 2004), pero su utilidad en cultivos protegidos para prevenir la entrada de insectos vectores en invernadero todavía no ha sido investigada. Los aditivos se incorporan al tejido durante el proceso de extrusión de la fibra y se liberan lentamente actuando por contacto en el momento en que el insecto aterriza sobre la malla, con lo cual el riesgo medioambiental y para la salud humana es muy limitado. Los plaguicidas que se emplean habitualmente suelen ser piretroides (deltametrina o bifentrín), aunque también se ha ensayado dicofol (Martin et al., 2010) y alfa-cipermetrina (Martin et al., 2014). Un factor que resulta de vital importancia en este tipo de mallas es el tamaño del poro para facilitar una buena ventilación del cultivo, al tiempo que se evita la entrada de insectos de pequeño tamaño como las moscas blancas (Bethke y Paine, 1991; Muñoz et al., 1999). Asimismo, se plantea la necesidad de estudiar la compatibilidad de estas mallas con los enemigos naturales. Es por ello que en esta Tesis Doctoral se plantea la necesidad de evaluar nuevas mallas impregnadas que impidan el paso de insectos de pequeño tamaño al interior de los invernaderos, pero que a su vez mantengan un buen intercambio y circulación de aire a través del poro de la malla. Así, en la presente Tesis Doctoral, se han planteado los siguientes objetivos generales a desarrollar: 1. Estudiar el impacto de la presencia de parasitoides sobre el grado de dispersión y los patrones de distribución de pulgones y las virosis que éstos transmiten. 2. Conocer el efecto directo de ambientes pobres en radiación UV sobre el comportamiento de vuelo de plagas clave de hortícolas y sus enemigos naturales. 3. Evaluar el efecto directo de la radiación UV-A sobre el crecimiento poblacional de pulgones y mosca blanca, y sobre la fisiología de sus plantas hospederas, así como el efecto indirecto de la radiación UV-A en ambas plagas mediado por el crecimiento de dichas planta hospederas. 4. Caracterización de diversas mallas impregnadas en deltametrina y bifentrín con diferentes propiedades y selección de las óptimas para el control de pulgones, mosca blanca y sus virosis asociadas en condiciones de campo. Estudio de su compatibilidad con parasitoides. ABSTRACT Insect vectors of plant viruses are the main agents causing major economic losses in vegetable crops grown under protected environments. This Thesis focuses on the implementation of new alternatives to chemical control of insect vectors under Integrated Pest Management programs. In Spain, biological control is the main pest control strategy used in a large part of greenhouses where horticultural crops are grown. The first study aimed to increase our knowledge on how the presence of natural enemies such as Aphidius colemani Viereck may alter the dispersal of the aphid vector Aphis gossypii Glover (Chapter 4). In addition, it was investigated if the presence of this parasitoid affected the spread of aphid-transmitted viruses Cucumber mosaic virus (CMV, Cucumovirus) and Cucurbit aphid-borne yellows virus (CABYV, Polerovirus) infecting cucumber (Cucumis sativus L). SADIE methodology was used to study the distribution patterns of both the virus and its vector, and their degree of association. Results suggested that parasitoids promoted aphid dispersal in the short term, which enhanced CMV spread, though consequences of parasitism suggested potential benefits for disease control in the long term. Furthermore, A. colemani significantly limited the spread and incidence of the persistent virus CABYV in the long term. The flight activity of pests Myzus persicae (Sulzer), Bemisia tabaci (Gennadius) and Tuta absoluta (Meyrick), and natural enemies A. colemani and Sphaerophoria rueppellii (Weidemann) under UV-deficient environments was studied under field conditions (Chapter 5). One-chamber tunnels were covered with cladding materials with different UV transmittance properties. Inside each tunnel, insects were released from tubes placed in a platform suspended from the ceiling. Specific targets were located at different distances from the platform. The ability of aphids and whiteflies to reach their targets was diminished under UV-absorbing barriers, suggesting a reduction of vector activity under this type of nets. Fewer aphids reached distant traps under UV-absorbing nets, and significantly more aphids could fly to the end of the tunnels covered with non-UV blocking materials. Unlike aphids, differences in B. tabaci captures were mainly found in the closest targets. The oviposition of lepidopteran T. absoluta was also negatively affected by a UV-absorbing cover. The photoselective barriers were compatible with parasitism and oviposition of biocontrol agents. Apart from the direct response of insects to UV radiation, plant-mediated effects influencing insect performance were investigated (Chapter 6). The impact of UV-A radiation on the performance of aphid M. persicae and whitefly B. tabaci, and growth and leaf physiology of host plants pepper and eggplant was studied under glasshouse conditions. Plants were grown inside cages covered by transparent and UV-A-opaque plastic films. Plant growth and insect fitness were monitored. Leaves were harvested for chemical analysis. Pepper plants responded directly to UV-A by producing shorter stems whilst UV-A did not affect the leaf area of either species. UV-A-treated peppers had higher content of secondary metabolites, soluble carbohydrates, free amino acids and proteins. Such changes in tissue chemistry indirectly promoted aphid performance. For eggplants, chlorophyll and carotenoid levels decreased with supplemental UVA but phenolics were not affected. Exposure to supplemental UV-A had a detrimental effect on whitefly development, fecundity and fertility presumably not mediated by plant cues, as compounds implied in pest nutrition were unaltered. Lastly, the efficacy of a wide range of Long Lasting Insecticide Treated Nets (LLITNs) was studied under laboratory and field conditions. This strategy aimed to prevent aphids and whiteflies to enter the greenhouse by determining the optimum mesh size (Chapter 7). This new approach is based on slow release deltamethrin- and bifenthrin-treated nets with large hole sizes that allow improved ventilation of greenhouses. All LLITNs produced high mortality of M. persicae and A. gossypii although their efficacy decreased over time with sun exposure. It was necessary a net with hole size of 0.29 mm2 to exclude B. tabaci under laboratory conditions. The feasibility of two selected nets was studied in the field under a high insect infestation pressure in the presence of CMV- and CABYV-infected cucumber plants. Besides, the compatibility of parasitoid A. colemani with bifenthrin-treated nets was studied in parallel field experiments. Both nets effectively blocked the invasion of aphids and reduced the incidence of both viruses, however they failed to exclude whiteflies. We found that our LLITNs were compatible with parasitoid A. colemani. As shown, the role of natural enemies has to be taken into account regarding the dispersal of insect vectors and subsequent spread of plant viruses. The additional benefits of novel physicochemical barriers, such as photoselective and insecticide-impregnated nets, need to be considered in Integrated Pest Management programs of vegetable crops grown under protected environments.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

El cerebro humano es probablemente uno de los sistemas más complejos a los que nos enfrentamos en la actualidad, si bien es también uno de los más fascinantes. Sin embargo, la compresión de cómo el cerebro organiza su actividad para llevar a cabo tareas complejas es un problema plagado de restos y obstáculos. En sus inicios la neuroimagen y la electrofisiología tenían como objetivo la identificación de regiones asociadas a activaciones relacionadas con tareas especificas, o con patrones locales que variaban en el tiempo dada cierta actividad. Sin embargo, actualmente existe un consenso acerca de que la actividad cerebral tiene un carácter temporal multiescala y espacialmente extendido, lo que lleva a considerar el cerebro como una gran red de áreas cerebrales coordinadas, cuyas conexiones funcionales son continuamente creadas y destruidas. Hasta hace poco, el énfasis de los estudios de la actividad cerebral funcional se han centrado en la identidad de los nodos particulares que forman estas redes, y en la caracterización de métricas de conectividad entre ellos: la hipótesis subyacente es que cada nodo, que es una representación mas bien aproximada de una región cerebral dada, ofrece a una única contribución al total de la red. Por tanto, la neuroimagen funcional integra los dos ingredientes básicos de la neuropsicología: la localización de la función cognitiva en módulos cerebrales especializados y el rol de las fibras de conexión en la integración de dichos módulos. Sin embargo, recientemente, la estructura y la función cerebral han empezado a ser investigadas mediante la Ciencia de la Redes, una interpretación mecánico-estadística de una antigua rama de las matemáticas: La teoría de grafos. La Ciencia de las Redes permite dotar a las redes funcionales de una gran cantidad de propiedades cuantitativas (robustez, centralidad, eficiencia, ...), y así enriquecer el conjunto de elementos que describen objetivamente la estructura y la función cerebral a disposición de los neurocientíficos. La conexión entre la Ciencia de las Redes y la Neurociencia ha aportado nuevos puntos de vista en la comprensión de la intrincada anatomía del cerebro, y de cómo las patrones de actividad cerebral se pueden sincronizar para generar las denominadas redes funcionales cerebrales, el principal objeto de estudio de esta Tesis Doctoral. Dentro de este contexto, la complejidad emerge como el puente entre las propiedades topológicas y dinámicas de los sistemas biológicos y, específicamente, en la relación entre la organización y la dinámica de las redes funcionales cerebrales. Esta Tesis Doctoral es, en términos generales, un estudio de cómo la actividad cerebral puede ser entendida como el resultado de una red de un sistema dinámico íntimamente relacionado con los procesos que ocurren en el cerebro. Con este fin, he realizado cinco estudios que tienen en cuenta ambos aspectos de dichas redes funcionales: el topológico y el dinámico. De esta manera, la Tesis está dividida en tres grandes partes: Introducción, Resultados y Discusión. En la primera parte, que comprende los Capítulos 1, 2 y 3, se hace un resumen de los conceptos más importantes de la Ciencia de las Redes relacionados al análisis de imágenes cerebrales. Concretamente, el Capitulo 1 está dedicado a introducir al lector en el mundo de la complejidad, en especial, a la complejidad topológica y dinámica de sistemas acoplados en red. El Capítulo 2 tiene como objetivo desarrollar los fundamentos biológicos, estructurales y funcionales del cerebro, cuando éste es interpretado como una red compleja. En el Capítulo 3, se resumen los objetivos esenciales y tareas que serán desarrolladas a lo largo de la segunda parte de la Tesis. La segunda parte es el núcleo de la Tesis, ya que contiene los resultados obtenidos a lo largo de los últimos cuatro años. Esta parte está dividida en cinco Capítulos, que contienen una versión detallada de las publicaciones llevadas a cabo durante esta Tesis. El Capítulo 4 está relacionado con la topología de las redes funcionales y, específicamente, con la detección y cuantificación de los nodos mas importantes: aquellos denominados “hubs” de la red. En el Capítulo 5 se muestra como las redes funcionales cerebrales pueden ser vistas no como una única red, sino más bien como una red-de-redes donde sus componentes tienen que coexistir en una situación de balance funcional. De esta forma, se investiga cómo los hemisferios cerebrales compiten para adquirir centralidad en la red-de-redes, y cómo esta interacción se mantiene (o no) cuando se introducen fallos deliberadamente en la red funcional. El Capítulo 6 va un paso mas allá al considerar las redes funcionales como sistemas vivos. En este Capítulo se muestra cómo al analizar la evolución de la topología de las redes, en vez de tratarlas como si estas fueran un sistema estático, podemos caracterizar mejor su estructura. Este hecho es especialmente relevante cuando se quiere tratar de encontrar diferencias entre grupos que desempeñan una tarea de memoria, en la que las redes funcionales tienen fuertes fluctuaciones. En el Capítulo 7 defino cómo crear redes parenclíticas a partir de bases de datos de actividad cerebral. Este nuevo tipo de redes, recientemente introducido para estudiar las anormalidades entre grupos de control y grupos anómalos, no ha sido implementado nunca en datos cerebrales y, en este Capítulo explico cómo hacerlo cuando se quiere evaluar la consistencia de la dinámica cerebral. Para concluir esta parte de la Tesis, el Capítulo 8 se centra en la relación entre las propiedades topológicas de los nodos dentro de una red y sus características dinámicas. Como mostraré más adelante, existe una relación entre ellas que revela que la posición de un nodo dentro una red está íntimamente correlacionada con sus propiedades dinámicas. Finalmente, la última parte de esta Tesis Doctoral está compuesta únicamente por el Capítulo 9, el cual contiene las conclusiones y perspectivas futuras que pueden surgir de los trabajos expuestos. En vista de todo lo anterior, espero que esta Tesis aporte una perspectiva complementaria sobre uno de los más extraordinarios sistemas complejos frente a los que nos encontramos: El cerebro humano. ABSTRACT The human brain is probably one of the most complex systems we are facing, thus being a timely and fascinating object of study. Characterizing how the brain organizes its activity to carry out complex tasks is highly non-trivial. While early neuroimaging and electrophysiological studies typically aimed at identifying patches of task-specific activations or local time-varying patterns of activity, there has now been consensus that task-related brain activity has a temporally multiscale, spatially extended character, as networks of coordinated brain areas are continuously formed and destroyed. Up until recently, though, the emphasis of functional brain activity studies has been on the identity of the particular nodes forming these networks, and on the characterization of connectivity metrics between them, the underlying covert hypothesis being that each node, constituting a coarse-grained representation of a given brain region, provides a unique contribution to the whole. Thus, functional neuroimaging initially integrated the two basic ingredients of early neuropsychology: localization of cognitive function into specialized brain modules and the role of connection fibres in the integration of various modules. Lately, brain structure and function have started being investigated using Network Science, a statistical mechanics understanding of an old branch of pure mathematics: graph theory. Network Science allows endowing networks with a great number of quantitative properties, thus vastly enriching the set of objective descriptors of brain structure and function at neuroscientists’ disposal. The link between Network Science and Neuroscience has shed light about how the entangled anatomy of the brain is, and how cortical activations may synchronize to generate the so-called functional brain networks, the principal object under study along this PhD Thesis. Within this context, complexity appears to be the bridge between the topological and dynamical properties of biological systems and, more specifically, the interplay between the organization and dynamics of functional brain networks. This PhD Thesis is, in general terms, a study of how cortical activations can be understood as the output of a network of dynamical systems that are intimately related with the processes occurring in the brain. In order to do that, I performed five studies that encompass both the topological and the dynamical aspects of such functional brain networks. In this way, the Thesis is divided into three major parts: Introduction, Results and Discussion. In the first part, comprising Chapters 1, 2 and 3, I make an overview of the main concepts of Network Science related to the analysis of brain imaging. More specifically, Chapter 1 is devoted to introducing the reader to the world of complexity, specially to the topological and dynamical complexity of networked systems. Chapter 2 aims to develop the biological, topological and functional fundamentals of the brain when it is seen as a complex network. Next, Chapter 3 summarizes the main objectives and tasks that will be developed along the forthcoming Chapters. The second part of the Thesis is, in turn, its core, since it contains the results obtained along these last four years. This part is divided into five Chapters, containing a detailed version of the publications carried out during the Thesis. Chapter 4 is related to the topology of functional networks and, more specifically, to the detection and quantification of the leading nodes of the network: the hubs. In Chapter 5 I will show that functional brain networks can be viewed not as a single network, but as a network-of-networks, where its components have to co-exist in a trade-off situation. In this way, I investigate how the brain hemispheres compete for acquiring the centrality of the network-of-networks and how this interplay is maintained (or not) when failures are introduced in the functional network. Chapter 6 goes one step beyond by considering functional networks as living systems. In this Chapter I show how analyzing the evolution of the network topology instead of treating it as a static system allows to better characterize functional networks. This fact is especially relevant when trying to find differences between groups performing certain memory tasks, where functional networks have strong fluctuations. In Chapter 7 I define how to create parenclitic networks from brain imaging datasets. This new kind of networks, recently introduced to study abnormalities between control and anomalous groups, have not been implemented with brain datasets and I explain in this Chapter how to do it when evaluating the consistency of brain dynamics. To conclude with this part of the Thesis, Chapter 8 is devoted to the interplay between the topological properties of the nodes within a network and their dynamical features. As I will show, there is an interplay between them which reveals that the position of a node in a network is intimately related with its dynamical properties. Finally, the last part of this PhD Thesis is composed only by Chapter 9, which contains the conclusions and future perspectives that may arise from the exposed results. In view of all, I hope that reading this Thesis will give a complementary perspective of one of the most extraordinary complex systems: The human brain.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In recent decades, full electric and hybrid electric vehicles have emerged as an alternative to conventional cars due to a range of factors, including environmental and economic aspects. These vehicles are the result of considerable efforts to seek ways of reducing the use of fossil fuel for vehicle propulsion. Sophisticated technologies such as hybrid and electric powertrains require careful study and optimization. Mathematical models play a key role at this point. Currently, many advanced mathematical analysis tools, as well as computer applications have been built for vehicle simulation purposes. Given the great interest of hybrid and electric powertrains, along with the increasing importance of reliable computer-based models, the author decided to integrate both aspects in the research purpose of this work. Furthermore, this is one of the first final degree projects held at the ETSII (Higher Technical School of Industrial Engineers) that covers the study of hybrid and electric propulsion systems. The present project is based on MBS3D 2.0, a specialized software for the dynamic simulation of multibody systems developed at the UPM Institute of Automobile Research (INSIA). Automobiles are a clear example of complex multibody systems, which are present in nearly every field of engineering. The work presented here benefits from the availability of MBS3D software. This program has proven to be a very efficient tool, with a highly developed underlying mathematical formulation. On this basis, the focus of this project is the extension of MBS3D features in order to be able to perform dynamic simulations of hybrid and electric vehicle models. This requires the joint simulation of the mechanical model of the vehicle, together with the model of the hybrid or electric powertrain. These sub-models belong to completely different physical domains. In fact the powertrain consists of energy storage systems, electrical machines and power electronics, connected to purely mechanical components (wheels, suspension, transmission, clutch…). The challenge today is to create a global vehicle model that is valid for computer simulation. Therefore, the main goal of this project is to apply co-simulation methodologies to a comprehensive model of an electric vehicle, where sub-models from different areas of engineering are coupled. The created electric vehicle (EV) model consists of a separately excited DC electric motor, a Li-ion battery pack, a DC/DC chopper converter and a multibody vehicle model. Co-simulation techniques allow car designers to simulate complex vehicle architectures and behaviors, which are usually difficult to implement in a real environment due to safety and/or economic reasons. In addition, multi-domain computational models help to detect the effects of different driving patterns and parameters and improve the models in a fast and effective way. Automotive designers can greatly benefit from a multidisciplinary approach of new hybrid and electric vehicles. In this case, the global electric vehicle model includes an electrical subsystem and a mechanical subsystem. The electrical subsystem consists of three basic components: electric motor, battery pack and power converter. A modular representation is used for building the dynamic model of the vehicle drivetrain. This means that every component of the drivetrain (submodule) is modeled separately and has its own general dynamic model, with clearly defined inputs and outputs. Then, all the particular submodules are assembled according to the drivetrain configuration and, in this way, the power flow across the components is completely determined. Dynamic models of electrical components are often based on equivalent circuits, where Kirchhoff’s voltage and current laws are applied to draw the algebraic and differential equations. Here, Randles circuit is used for dynamic modeling of the battery and the electric motor is modeled through the analysis of the equivalent circuit of a separately excited DC motor, where the power converter is included. The mechanical subsystem is defined by MBS3D equations. These equations consider the position, velocity and acceleration of all the bodies comprising the vehicle multibody system. MBS3D 2.0 is entirely written in MATLAB and the structure of the program has been thoroughly studied and understood by the author. MBS3D software is adapted according to the requirements of the applied co-simulation method. Some of the core functions are modified, such as integrator and graphics, and several auxiliary functions are added in order to compute the mathematical model of the electrical components. By coupling and co-simulating both subsystems, it is possible to evaluate the dynamic interaction among all the components of the drivetrain. ‘Tight-coupling’ method is used to cosimulate the sub-models. This approach integrates all subsystems simultaneously and the results of the integration are exchanged by function-call. This means that the integration is done jointly for the mechanical and the electrical subsystem, under a single integrator and then, the speed of integration is determined by the slower subsystem. Simulations are then used to show the performance of the developed EV model. However, this project focuses more on the validation of the computational and mathematical tool for electric and hybrid vehicle simulation. For this purpose, a detailed study and comparison of different integrators within the MATLAB environment is done. Consequently, the main efforts are directed towards the implementation of co-simulation techniques in MBS3D software. In this regard, it is not intended to create an extremely precise EV model in terms of real vehicle performance, although an acceptable level of accuracy is achieved. The gap between the EV model and the real system is filled, in a way, by introducing the gas and brake pedals input, which reflects the actual driver behavior. This input is included directly in the differential equations of the model, and determines the amount of current provided to the electric motor. For a separately excited DC motor, the rotor current is proportional to the traction torque delivered to the car wheels. Therefore, as it occurs in the case of real vehicle models, the propulsion torque in the mathematical model is controlled through acceleration and brake pedal commands. The designed transmission system also includes a reduction gear that adapts the torque coming for the motor drive and transfers it. The main contribution of this project is, therefore, the implementation of a new calculation path for the wheel torques, based on performance characteristics and outputs of the electric powertrain model. Originally, the wheel traction and braking torques were input to MBS3D through a vector directly computed by the user in a MATLAB script. Now, they are calculated as a function of the motor current which, in turn, depends on the current provided by the battery pack across the DC/DC chopper converter. The motor and battery currents and voltages are the solutions of the electrical ODE (Ordinary Differential Equation) system coupled to the multibody system. Simultaneously, the outputs of MBS3D model are the position, velocity and acceleration of the vehicle at all times. The motor shaft speed is computed from the output vehicle speed considering the wheel radius, the gear reduction ratio and the transmission efficiency. This motor shaft speed, somehow available from MBS3D model, is then introduced in the differential equations corresponding to the electrical subsystem. In this way, MBS3D and the electrical powertrain model are interconnected and both subsystems exchange values resulting as expected with tight-coupling approach.When programming mathematical models of complex systems, code optimization is a key step in the process. A way to improve the overall performance of the integration, making use of C/C++ as an alternative programming language, is described and implemented. Although this entails a higher computational burden, it leads to important advantages regarding cosimulation speed and stability. In order to do this, it is necessary to integrate MATLAB with another integrated development environment (IDE), where C/C++ code can be generated and executed. In this project, C/C++ files are programmed in Microsoft Visual Studio and the interface between both IDEs is created by building C/C++ MEX file functions. These programs contain functions or subroutines that can be dynamically linked and executed from MATLAB. This process achieves reductions in simulation time up to two orders of magnitude. The tests performed with different integrators, also reveal the stiff character of the differential equations corresponding to the electrical subsystem, and allow the improvement of the cosimulation process. When varying the parameters of the integration and/or the initial conditions of the problem, the solutions of the system of equations show better dynamic response and stability, depending on the integrator used. Several integrators, with variable and non-variable step-size, and for stiff and non-stiff problems are applied to the coupled ODE system. Then, the results are analyzed, compared and discussed. From all the above, the project can be divided into four main parts: 1. Creation of the equation-based electric vehicle model; 2. Programming, simulation and adjustment of the electric vehicle model; 3. Application of co-simulation methodologies to MBS3D and the electric powertrain subsystem; and 4. Code optimization and study of different integrators. Additionally, in order to deeply understand the context of the project, the first chapters include an introduction to basic vehicle dynamics, current classification of hybrid and electric vehicles and an explanation of the involved technologies such as brake energy regeneration, electric and non-electric propulsion systems for EVs and HEVs (hybrid electric vehicles) and their control strategies. Later, the problem of dynamic modeling of hybrid and electric vehicles is discussed. The integrated development environment and the simulation tool are also briefly described. The core chapters include an explanation of the major co-simulation methodologies and how they have been programmed and applied to the electric powertrain model together with the multibody system dynamic model. Finally, the last chapters summarize the main results and conclusions of the project and propose further research topics. In conclusion, co-simulation methodologies are applicable within the integrated development environments MATLAB and Visual Studio, and the simulation tool MBS3D 2.0, where equation-based models of multidisciplinary subsystems, consisting of mechanical and electrical components, are coupled and integrated in a very efficient way.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Biological sensing of small molecules such as NO, O2, and CO is an important area of research; however, little is know about how CO is sensed biologically. The photosynthetic bacterium Rhodospirillum rubrum responds to CO by activating transcription of two operons that encode a CO-oxidizing system. A protein, CooA, has been identified as necessary for this response. CooA is a member of a family of transcriptional regulators similar to the cAMP receptor protein and fumavate nitrate reduction from Escherichia coli. In this study we report the purification of wild-type CooA from its native organism, R. rubrum, to greater than 95% purity. The purified protein is active in sequence-specific DNA binding in the presence of CO, but not in the absence of CO. Gel filtration experiments reveal the protein to be a dimer in the absence of CO. Purified CooA contains 1.6 mol heme per mol of dimer. Upon interacting with CO, the electronic spectrum of CooA is perturbed, indicating the direct binding of CO to the heme of CooA. A hypothesis for the mechanism of the protein’s response to CO is proposed.