759 resultados para Calabi-Yau manifold


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In this dissertation I will study the phenomenon of the hipérbole sacroprofana in different Castillian writers of the 15th to the 17th centuries, in order to show in what does this fact consists, and how it has to be sorted out. Thus, I will also show how this tendency unfolds and how the use of either one or another resource leads the hipérbole towards different expressive horizons. Although the hipérbole sacroprofana is usually detected by most of scholars, it has never met proper attention, so that it has turned into a jumble in which the most disparate instances of a lady’s praise. Yet, an accurate analysis of this phenomenon reveals that this is not the case, and that this resource has manifold aspects and varying intentions and expressive ways as well. In this dissertation, where some five thousand hipérboles are analysed, I point out the various kinds of instances, and I classify them according to their expression and their literary-intellectual interweaving. Besides I monitor this fact to explain how hipérbole varies with the passage of times. By so doing a deficiency in the history of literary criticism, which mistook and likened all sorts of hipérboles in poetical texts, is eased. So we can see that, in its origins, hipérbole was confined to using sacred terms in profane poems out of their context (which I call hipérbole léxica o de inserción terminológica). This resource was effectual insofar as the use of words religiously connoted carried along devout attitudes towards poems of earthly love so that the lady and the feeling that the author professed became “adulterated” by Christian attitudes...

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The Eemian (last interglacial, 130-115 ka) was likely the warmest of all interglacials of the last 800 ka, with summer Arctic temperatures 3-5 degrees C above present. Here, we present improved Eemian climate records from central Greenland, reconstructed from the base of the Greenland Ice Sheet Project 2 (GISP2) ice core. Our record comes from clean, stratigraphically disturbed, and isotopically warm ice from 2,750 to 3,040 m depth. The age of this ice is constrained by measuring CH_4 and delta O^18 of O_2, and comparing with the historical record of these properties from the North Greenland Ice Core Project (NGRIP) and North Greenland Eemian Ice Drilling (NEEM) ice cores. The d^18 O_ice, d^15N of N_2, and total air content for samples dating discontinuously from 128 to 115 ka indicate a warming of similar to 6 degrees C between 127-121 ka, and a similar elevation history between GISP2 and NEEM. The reconstructed climate and elevation histories are compared with an ensemble of coupled climate-ice-sheet model simulations of the Greenland ice sheet. Those most consistent with the reconstructed temperatures indicate that the Greenland ice sheet contributed 5.1 m (4.1-6.2 m, 95% credible interval) to global eustatic sea level toward the end of the Eemian. Greenland likely did not contribute to anomalously high sea levels at ~127 ka, or to a rapid jump in sea level at ~120 ka. However, several unexplained discrepancies remain between the inferred and simulated histories of temperature and accumulation rate at GISP2 and NEEM, as well as between the climatic reconstructions themselves.

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It is a widely acknowledged and often unquestioned fact that patriarchy and its modes of behaviour and social organization favour the appearance of trauma on the weakest (and defenceless) members of society: women. In the last decades, trauma seems to have taken the baton of typically female maladies such as 19th c. hysteria or 20th c. madness. Feminists in the 20th c. have long worked to prove the connection between the latter affections (and their reflection in literary texts) and patriarchal oppression or expectations of feminine behaviour and accordance to roles and rules. With Trauma Studies on the rise, the approach to the idea of the untold as related to femininity is manifold: on the one hand, is not trauma, which precludes telling about one’s own experience and keeps it locked not only from the others, but also from ourselves, the ultimate secrecy? On the other hand, when analyzing works that reflect trauma, one is astounded by the high number of them with a female protagonist and an almost all-female cast: in this sense, a ‘feminist’ reading is almost compulsory, in the sense that it is usually the author’s assumption that patriarchal systems of exploitation and expectations favour traumatic events and their outcome (silence and secrets) on the powerless, usually women. Often, traumatic texts combine feminism with other analytical discourses (one of the topics proposed for this panel): Toni Morrison’s study of traumatic responses in The Bluest Eye and Beloved cannot be untangled from her critique of slavery; just as much of Chicana feminism and its representations of rape and abuse (two main agents of trauma) analyze the nexus of patriarchy, new forms of post-colonialism, and the dynamics of power and powerlessness in ethnic contexts. Within this tradition that establishes the secrecies of trauma as an almost exclusively feminine characteristic, one is however faced with texts which have traumatized males as protagonists: curiously enough, most of these characters have suffered trauma through a typically masculine experience: that of war and its aftermath. By analyzing novels dealing with war veterans from Vietnam or the Second World War, the astounding findings are the frequent mixture of masculine or even ‘macho’ values and the denial of any kind of ‘feminine’ characteristics, combined with a very strict set of rules of power and hierarchy that clearly establish who is empowered and who is powerless. It is our argument that this replication of patriarchal modes of domination, which place the lowest ranks of the army in a ‘feminine’ situation, blended with the compulsory ‘macho’ stance soldiers are forced to adopt as army men (as seen, for example, in Philip Caputo’s Indian Country, Larry Heinemann’s Paco’s Story or Ed Dodge’s DAU: A Novel of Vietnam) furthers the onset and seriousness of ulterior trauma. In this sense, we can also analyze this kind of writing from a ‘feminist’ point of view, since the dynamics of über-patriarchal power established at the front at war-time deny any display of elements traditionally viewed as ‘feminine’ (such as grief, guilt or emotions) in soldiers. If trauma is the result of a game of patriarchal empowerment, how can feminist works, not only theoretical, but also fictional, overthrow it? Are ‘feminine’ characteristics necessary to escape trauma, even in male victims? How can feminist readings of trauma enhance our understanding of its dynamics and help produce new modes of interaction that transcend power and gender division as the basis for the organization of society?

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It is well-recognized that exercise improves mental health, e.g., by decreasing depressive behaviors, improving hippocampal-dependent learning and neurogenesis, and increasing dendritic plasticity. Yet how exercise influences the brain at the molecular level is not clearly understood. Yau et al recently reported that the antidepressant effects of physical exercise are mainly mediated by adiponectin, an adipocyte-secreted hormone ('adipocytokine') with neuroprotective effects at the central nervous system level (Yau et al., 2014). This article is protected by copyright. All rights reserved

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The aims of this thesis were to determine the animal health status in organic dairy farms in Europe and to identify drivers for improving the current situation by means of a systemic approach. Prevalences of production diseases were determined in 192 herds in Germany, France, Spain, and Sweden (Paper I), and stakeholder consultations were performed to investigate potential drivers to improve animal health on the sector level (ibid.). Interactions between farm variables were assessed through impact analysis and evaluated to identify general system behaviour and classify components according to their outgoing and incoming impacts (Paper II-III). The mean values and variances of prevalences indicate that the common rules of organic dairy farming in Europe do not result in consistently low levels of production diseases. Stakeholders deemed it necessary to improve the current status and were generally in favour of establishing thresholds for the prevalence of production diseases in organic dairy herds as well as taking actions to improve farms below that threshold. In order to close the gap between the organic principle of health and the organic farming practice, there is the need to formulate a common objective of good animal health and to install instruments to ensure and prove that the aim is followed by all dairy farmers in Europe who sell their products under the organic label. Regular monitoring and evaluation of herd health performance based on reference values are considered preconditions for identifying farms not reaching the target and thus in need of improvement. Graph-based impact analysis was shown to be a suitable method for modeling and evaluating the manifold interactions between farm factors and for identifying the most influential components on the farm level taking into account direct and indirect impacts as well as impact strengths. Variables likely to affect the system as a whole, and the prevalence of production diseases in particular, varied largely between farms despite some general tendencies. This finding reflects the diversity of farm systems and underlines the importance of applying systemic approaches in health management. Reducing the complexity of farm systems and indicating farm-specific drivers, i.e. areas in a farm, where changes will have a large impact, the presented approach has the potential to complement and enrich current advisory practice and to support farmers’ decision-making in terms of animal health.

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Résumé : À l’aube des études humiennes, Norman Kemp Smith appelait à représenter Hume « suivant toutes ses nombreuses activités », comme s’il pressentait que l’étude de la pensée humienne pouvait s’avérer un labyrinthe dans lesquels les commentaires pouvaient s’égarer et se perdre de vue. Ce pressentiment, on peut le dire aujourd’hui, s’est avéré juste, et il porte avec lui une clé de lecture : pour dépasser la représentation parcellaire, fragmentée et ultimement incohérente d’un Hume kaléidoscopique, le mieux est peut-être de s’intéresser à ses activités. La présente thèse vise à circonscrire la pratique humienne de la philosophie, ou, pourrait-on dire, du travail épistémologique et conceptuel, dans l’espace de son magnum opus, et cela à l’aide d’une clé de lecture : celle du réductionnisme. Si le Traité est une oeuvre que l’on peut qualifier d’empiriste, on ne saurait la lire seulement par ce biais ou par celui de questions localisées, et nous montrons que le projet du Traité ne peut se comprendre qu’en voyant comment Hume tente d’y réduire la et les connaissances à des dépendances ou à des parties de sa propre théorie de la nature humaine. Pour cela, nous procédons via quatre chapitres. D’abord, nous tentons de circonscrire les caractéristiques les plus importantes du projet humien, c’est-à-dire de ce que Hume avait l’intention de développer à travers les contenus particuliers du Traité ; ensuite, nous nous concentrons sur la base dont Hume part et dont il se servira pour accomplir des réductions, base que l’on peut appeler une théorie des perceptions doublée d’une théorie de l’esprit (principes, facultés, relations) ; ces deux théories, couplées à un standard strict pour obtenir le statut de « vraie idée » ou d’idée intelligible, semblent amener de par leurs prémisses assez directement au scepticisme, et c’est pourquoi on traitera du scepticisme avant d’évoquer les aspects « naturalistes » du Traité au-delà des éléments de base de la théorie des perceptions et de l’esprit, soit une manoeuvre qui ne suit pas tout à fait l’ordre humien d’exposition mais nous semble suivre un certain ordre des raisons ; enfin, la quatrième partie nous permettra de passer en revue diverses réductions opérées par Hume, celles qui mènent au scepticisme pyrrhonien mises à part, ce qui nous permettra de voir quelles sont les limites et les problèmes afférents à son réductionnisme particulier. Refondateur, systématique et totalisant dans ses intentions, le Traité suit bien plus qu’un projet simplement empiriste, et on verra que dans la démarche humienne l’empirisme apparaît davantage dans les conclusions qu’au point même de départ. En le lisant comme le lieu et la conséquence d’une orientation que l’on peut dire réductionniste, on peut trouver dans le Traité un fil conducteur qui, en dépit de problèmes plus ou moins importants rencontrés en cours de route, ne se rompt pas.

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The idea of spacecraft formations, flying in tight configurations with maximum baselines of a few hundred meters in low-Earth orbits, has generated widespread interest over the last several years. Nevertheless, controlling the movement of spacecraft in formation poses difficulties, such as in-orbit high-computing demand and collision avoidance capabilities, which escalate as the number of units in the formation is increased and complicated nonlinear effects are imposed to the dynamics, together with uncertainty which may arise from the lack of knowledge of system parameters. These requirements have led to the need of reliable linear and nonlinear controllers in terms of relative and absolute dynamics. The objective of this thesis is, therefore, to introduce new control methods to allow spacecraft in formation, with circular/elliptical reference orbits, to efficiently execute safe autonomous manoeuvres. These controllers distinguish from the bulk of literature in that they merge guidance laws never applied before to spacecraft formation flying and collision avoidance capacities into a single control strategy. For this purpose, three control schemes are presented: linear optimal regulation, linear optimal estimation and adaptive nonlinear control. In general terms, the proposed control approaches command the dynamical performance of one or several followers with respect to a leader to asymptotically track a time-varying nominal trajectory (TVNT), while the threat of collision between the followers is reduced by repelling accelerations obtained from the collision avoidance scheme during the periods of closest proximity. Linear optimal regulation is achieved through a Riccati-based tracking controller. Within this control strategy, the controller provides guidance and tracking toward a desired TVNT, optimizing fuel consumption by Riccati procedure using a non-infinite cost function defined in terms of the desired TVNT, while repelling accelerations generated from the CAS will ensure evasive actions between the elements of the formation. The relative dynamics model, suitable for circular and eccentric low-Earth reference orbits, is based on the Tschauner and Hempel equations, and includes a control input and a nonlinear term corresponding to the CAS repelling accelerations. Linear optimal estimation is built on the forward-in-time separation principle. This controller encompasses two stages: regulation and estimation. The first stage requires the design of a full state feedback controller using the state vector reconstructed by means of the estimator. The second stage requires the design of an additional dynamical system, the estimator, to obtain the states which cannot be measured in order to approximately reconstruct the full state vector. Then, the separation principle states that an observer built for a known input can also be used to estimate the state of the system and to generate the control input. This allows the design of the observer and the feedback independently, by exploiting the advantages of linear quadratic regulator theory, in order to estimate the states of a dynamical system with model and sensor uncertainty. The relative dynamics is described with the linear system used in the previous controller, with a control input and nonlinearities entering via the repelling accelerations from the CAS during collision avoidance events. Moreover, sensor uncertainty is added to the control process by considering carrier-phase differential GPS (CDGPS) velocity measurement error. An adaptive control law capable of delivering superior closed-loop performance when compared to the certainty-equivalence (CE) adaptive controllers is finally presented. A novel noncertainty-equivalence controller based on the Immersion and Invariance paradigm for close-manoeuvring spacecraft formation flying in both circular and elliptical low-Earth reference orbits is introduced. The proposed control scheme achieves stabilization by immersing the plant dynamics into a target dynamical system (or manifold) that captures the desired dynamical behaviour. They key feature of this methodology is the addition of a new term to the classical certainty-equivalence control approach that, in conjunction with the parameter update law, is designed to achieve adaptive stabilization. This parameter has the ultimate task of shaping the manifold into which the adaptive system is immersed. The performance of the controller is proven stable via a Lyapunov-based analysis and Barbalat’s lemma. In order to evaluate the design of the controllers, test cases based on the physical and orbital features of the Prototype Research Instruments and Space Mission Technology Advancement (PRISMA) are implemented, extending the number of elements in the formation into scenarios with reconfigurations and on-orbit position switching in elliptical low-Earth reference orbits. An extensive analysis and comparison of the performance of the controllers in terms of total Δv and fuel consumption, with and without the effects of the CAS, is presented. These results show that the three proposed controllers allow the followers to asymptotically track the desired nominal trajectory and, additionally, those simulations including CAS show an effective decrease of collision risk during the performance of the manoeuvre.

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We prove a Theorem on homotheties between two given tangent sphere bundles SrM of a Riemannian manifold (M,g) of dim ≥ 3, assuming different variable radius functions r and weighted Sasaki metrics induced by the conformal class of g. New examples are shown of manifolds with constant positive or with constant negative scalar curvature which are not Einstein. Recalling results on the associated almost complex structure I^G and symplectic structure ω^G on the manifold TM , generalizing the well-known structure of Sasaki by admitting weights and connections with torsion, we compute the Chern and the Stiefel-Whitney characteristic classes of the manifolds TM and SrM.

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Access, participation and exclusion from higher education for marginalized and disadvan-taged sections of the population are an intricate socio-political as well as economic practice that has manifold explanations and outcomes. During the last three decades, the higher education has experienced expansion in both enrolments and institutions. The approaches and means of delivery have changed besides the diversification in provision. The role of the state and mar¬ket has also reformed. This characteristic has also altered the nature of equity in higher edu¬cation across the globe. The chapters of this book on different countries of Asia, Europe and Latin America examine access and describe the several spaces where cohorts of relevant age group are included, excluded, or are at threat of exclusion in higher education. The chapters also narrate the state of affairs in which despite numerous alike structure in the experience and outcomes of social exclusion across disenfranchised groups and regions, how some critical differences have led to different paths of struggles and policy formation to attain the objective of equity in higher education.