431 research outputs found
Using Semiochemicals for Coleopterean Pests in Sustainable Plant Protection
Since the early twentieth century, chemical industry provides farmers large amounts of synthetic chemicals used as fertilizers and pest control products. Agriculture became intensive and the crop yields and the profit increased dramatically. Tons of toxic material for crop protection and fertilization were scattered through the gardens, fields, and orchards. But all these chemicals affect the environment, with serious negative consequences for humanity, today and tomorrow. Since 1959 until today many researchers observed and discussed the disadvantages of chemical methods of combating harmful insects and misapplied their disruptive action on cultivated ecosystems. Integrated pest management (IPM) is a process used to solve pest problems with minimum risks to people and environment. The objective of the researches presented in this chapter is to obtain and testing “semiochemicals”—pheromones, involved in intraspecific communication, into environmentally compatible strategies, to reduce pest populations under economic damage thresholds. Insect that are monitored and mass trapped in proposed IPM strategies are potato pest, Colorado potato beetle, Lepidoptera decemlineata Say (Coleoptera, Chrisomelidae); corn pests, West Corn Rootworm Diabrotica virgifera virgifera (Coleoptera, Chrisomelidae); and six-spined bark beetle Pityogenes chalcographus (Coleoptera, Scolitydae) pest in coniferous forests
Emergent topological fields and relativistic phonons within the thermoelectricity in topological insulators
Topological edge states are predicted to be responsible for the high efficient thermoelectric response of topological insulators, currently the best thermoelectric materials. However, to explain their figure of merit the coexistence of topological electrons, entropy and phonons can not be considered independently. In a background that puts together electrodynamics and topology, through an expression for the topological intrinsic field, we treat relativistic phonons within the topological surface showing their ability to modulate the Berry curvature of the bands and then playing a fundamental role in the thermoelectric effect. Finally, we show how the topological insulators under such relativistic thermal excitations keep time reversal symmetry allowing the observation of high figures of merit at high temperatures. The emergence of this new intrinsic topological field and other constraints are suitable to have experimental consequences opening new possibilities of improving the efficiency of this topological effect for their based technologyAuthors acknowledge to CESGA, AEMAT ED431E 2018/08, PID2019-104150RB-I00 and the MAT2016-80762-R project for financial supportS
On Behind the Physics of the Thermoelectricity of Topological Insulators
Topological Insulators are the best thermoelectric materials involving a sophisticated physics beyond their solid state and electronic structure. We show that exists a topological contribution to the thermoelectric effect that arises between topological and thermal quantum field theories applied at very low energies. This formalism provides us with a quantized topological mass proportional to the temperature T leading, through an electric potential V, to a Seebeck coefficient where we identify an anomalous contribution that can be associated to the creation of real electron-hole Schwinger’s pairs close to the topological bands. Finally, we find a general expression for the dimensionless figure of merit of these topological materials, considering only the electronic contribution, getting a value of 2.73 that is applicable to the Bi2Te3, for which it was reported a value of 2.4 after reducing its phononic contribution, using only the most basic topological numbers (0 or 1).Thanks to the CESGA, to AEMAT ED431E 2018/08 and the MAT2016-80762-R project for financial support.S
Anomalous response in the orbital magnetic susceptibility of 2d topological systems
2D compounds with nonzero Berry curvature are ideal systems to study exotic and technologically favorable thermoelectric and magnetoelectric properties. Within this class of materials, the topological trivial and nontrivial regimes have to present very different behaviors, which are encoded for the orbital susceptibility and magnetization. To try to reveal them, it is found that it was necessary to introduce a k-dependent mass term in the relativistic formalism of these materials. Thus, while a topologically trivial insulator is predicted to have a very limited response, in the nontrivial regime, a singular contribution to the orbital magnetic susceptibility, which is inversely proportional to the square of the quantum magnetic flux is unveiled. In this scenario, besides determining the measurement conditions a new route for enhancing the intrinsic orbital magnetism of topological materials widening the range of temperatures and magnetic fields without involving tiny bandgaps is foundThe authors acknowledge PID2019-104150RB-I00, AEMAT ED431E 2018/08 and the MAT2016-80762-R projects for financial support. The authors thank Juan Manuel Faílde for the helpful discussionsS
Comportement des matériaux composites à renforts tricotés élaborés par injection de résine
Les textiles tricotés présentent un grand intérêt pour le renforcement de composites et notamment pour la mise en œuvre de pièces de formes complexes, cependant, l'orientation non alignée des fibres confère au composite des propriétés mécaniques limitées. L'amélioration de ces propriétés nécessite une optimisation de la contexture fibreuse. Dans ce contexte, le travail de thèse vise à étudier le comportement des composites à renforts tricotés et le mettre en relation avec l'architecture du tricot, la nature de la fibre et le comportement du textile sec. Dans un premier temps, le comportement des tricots secs a été étudié en fonction de leur architecture et de la nature de la fibre (verre, basalte et carbone) en se consacrant d'abord aux contextures de référence (cote et jersey), puis en insérant des mèches non tricotés dans la rangée du jersey. Dans une seconde phase, des composites renforcés de ces même contextures ont été élaborés par
injection de résine et soumis à des essais de traction. La stéréo-corrélation d'images a été utilisée pour mettre en évidence l'hétérogénéité des déformations due au renfort fibreux et pour expliquer les différences de comportement en fonction de la direction de sollicitation. L'endommagement a été étudié par l'observation des faciès de rupture. Dans une dernière phase, une modélisation semi-analytique du comportement des tricots jersey secs basée sur la théorie de l'élasticité permet d'obtenir un modèle géométrique de la maille jersey quel que soit l'état de déformation du tricot. L'orientation des fibres calculée est utilisée pour alimenter un modèle d'estimation des propriétés élastiques des composites basé sur le principe d'homogénéisation. Les résultats sont comparés avec l'expérience et montrent une bonne corrélation. Ce modèle permet en outre de prendre en compte la présence des mèches insérées dans la rangée du jersey ainsi qu'une prétension initiale du renfort avant mise en œuvre et ainsi, de définir une architecture du renfort optimisée pour améliorer les propriétés du composite.Knitted fabrics are of great interest for reinforcing composites and particularly for producing complex and 3D shape parts due to their high drapability and their automation capability. Nevertheless the looped structure of the reinforcement confers to the composite poor in plane mechanical properties. Improving these properties requires an optimization of the fabric architecture. The aim of this thesis is to study the mechanical behaviour of weft-knitted reinforced composites and to relate it with the fabric architecture, the fibre type and the dry preform behaviour. In a first step, tensile behaviour of the dry knitted fabrics has been studied according to their architecture and the fibre type (E-glass, basalt and carbon), focusing first on the basic knitted fabrics (1x1 rib and plain), and then by inserting inlay yarns in the course direction of the plain knit fabric. In a second step, composite plates, reinforced by these knitted preforms were
elaborated by resin injection and subjected to tensile tests. Digital Image Correlation has been used to highlight the deformation heterogeneity due to knitted reinforcement and explain the difference of behaviour depending on loading
direction. Damages have been studied by the fracture pattern observation. In a last step, the semi-analytical modeling of
the plain-knit fabric behaviour, based on the theory of elasticity, gives a geometrical model of the plain stitch for any deformed state of the fabric. The fibre orientation calculated has been used in an homogeneization model for estimating the elastic properties of the resulting composite. Theoretical results are in good agreement with those obtained experimentally. This model allows to take into account the presence of the inlay yarns and also an initial extension of the reinforcement before composite elaboration and thus to define an optimized architecture of the knitted fabric to improve the properties of the composite
O impacto da política de cohesión europea na converxencia real rexional O caso de Galicia (1980-2016)
[Resumo]: O obxectivo deste traballo é analiza-lo impacto da política de cohesión da UE na converxencia real a nivel rexional, centrando a análise no caso galego para o período 1980-2016. En primeiro lugar, analizouse a evolución histórica da política de cohesión europea e os seus obxectivos no período 1986-2016, realizouse unha revisión bibliográfica da literatura científica sobre converxencia e identificáronse os factores determinantes do crecemento rexional e a converxencia real (evolución da poboación e movementos migratorios, dotación de infraestruturas, produtividade aparente do traballo, estrutura produtiva –entendida coma especialización sectorial–, capital humano, taxa de ocupación, capital tecnolóxico e investimento en I+D, grao de apertura comercial). Posteriormente, estudouse se a política de cohesión aplicada en Galicia tivo en conta os factores determinantes da converxencia e se incidiu adecuadamente nos mesmos, sendo a resposta afirmativa. Por outro lado, realizouse unha análise empírica da evolución das Comunidades Autónomas españolas no período 1980-2016. Atopando a existencia de concentración espacial da riqueza e da poboación e un proceso de diverxencia entre as Comunidades Autónomas máis ricas, que crecen por riba da media, e as máis pobres, que crecen por debaixo da media. Proceso ocultado, ó realizar unha análise agregada de σ-converxencia, polo proceso de rápida converxencia de Baleares e Estremadura. Ademais, realizouse unha análise empírica detallada de Galicia, na que se descubre que a converxencia en PIBpc coa media española se produce unicamente pola perda de poboación relativa, xa que Galicia perde peso económico dentro do conxunto do Estado de modo continuado, e que a converxencia en termos de IDH foi máis positiva. Tamén se analizou o papel xogado polos factores determinantes da converxencia galega coa media española considerados máis relevantes, sendo a evidencia empírica consistente coa optida ó analiza-la incidencia da política de cohesión aplicada en Galicia nos mesmos (incidencia positiva).[Abstract]: The aim of this paper is to analyze the impact of the cohesion policy of the EU in the real convergence at the regional level, focusing the analysis in the Galician case for the period 1980-2016. In the first place, the historical evolution of the European cohesion policy and its objectives in the period 1986-2016 were analyzed, a bibliographical review of the scientific literacy about convergence was conducted, and the key factors of the regional growth and the real convergence were identified (population evolution and migratory movements, infrastructures endowment, apparent productivity of labour, productive structure –understood as sectoral specialization–, human capital, employment rate, technological capital and R&D investment, and degree of trade openness). Subsequently, it was studied if the cohesion policy deployed in Galicia took into account the key factors of the convergence and if the cohesion policy had a positive impact in those, being the answer affirmative. On the other hand, an empirical analysis of the performance of the Spanish Autonomous Communities in the period 1980-2016 was conducted. We founded spatial concentration of the population and of the wealth and a process of divergence between the wealthier Autonomous Communities –those who grow above the mean– and the poorer Autonomous Communities –those who grow under the mean–. When an aggregate analysis of σ-convergence is conducted, this process is masked because of the fast convergence of the Balearic islands and of Extremadura. Also, a detailed empiric analysis of Galicia was conducted, which showed the fact that the convergence of Galicia with the Spanish mean –in terms of PIBpc– only took placed due to the loss of relative population of Galicia, since Galicia lost economic weight in a continuous basis, and the convergence in terms of HDI was more positive. The role played by the key factors of the convergence of Galicia with the Spanish mean was also studied, being the empirical evidence consistent with the results obtained when the analysis of the incidence of the cohesion policy deployed in Galicia was conducted (i.e. positive incidence).Traballo fin de grao (UDC.ECO). ADE. Curso 2016/201
Responsabilidades penales y concurso de acreedores de Balea, SA
Traballo fin de grao (UDC.DER). Dereito. Curso 2016/201
Neuroprotection and Recovery in Multiple Sclerosis
Multiple sclerosis is a complex and heterogeneous immune-mediated disease that results in the progressive accumulation of mental and physical symptoms. Currently approved disease-modifying drugs (DMDs) are immunomodulatory or immunosuppressive, but these drugs have little effect on disease progression. In addition to studies that have directly targeted inflammation and immune responses, a large number of studies, most of them experimental, have investigated neuroprotective therapies and remyelination strategies. However, to date, attempts to provide neuroprotection have failed not just in multiple sclerosis but in neurological disorders in general; this situation has emphasized the need to revise the old paradigm of a “magic bullet” with a single mechanism of action. Remyelination strategies involve either promoting endogenous remyelination or replacing lost myelinating cells through exogenous sources. However, several puzzle pieces regarding the physiology of remyelination remain unknown, including feasible treatment monitoring methods, the selection of patients, and the optimal time of treatment initiation. This chapter will describe the direct and indirect neuroprotective effects of DMDs, as suggested by basic research studies and confirmed by clinical studies in some cases. Current knowledge of potential neuroprotective therapies and remyelination strategies is also reviewed
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