The relevance of sport-related behaviour patterns in the family for the sport participation of youth in Switzerland

Despite various efforts to promote sport participation among youth, social inequalities still exist. An explanation for these social inequalities could be traced back to transgenerational transmission of sport-related values and behaviour patterns in a family (Baur, 1989). Therefore, children’s socialisation to sport is strongly influenced by the parents’ sport-related values and sport behaviour (Burrmann, 2005). However, findings of previous studies are inconsistent, and the daily sport-related behaviour patterns of families have often not been taken into account. The paper deals with the question, to what extent sport participation of youth is influenced by factors such as the importance of sport, the self-evidence of regular sport activity, mutual support, shared sport activities, sport-related health-awareness and communication about sport in the family. In order to pursue this research question, socialisation theories were used as theoretical framework (Hurrelmann, 2006). Based on this approach, a quantitative online survey where 4’039 adolescents and young adults from the ages of 15 to 30 (n = 4’039, M = 21.48, SD = 4.64) answered questions according their sport participation and the sport-related patterns of their families. Furthermore, a qualitative study that included guideline-based interviews with adolescents and young adults (n = 13) were undertaken. Content analysis was used to analyse the interviews. Initial findings of the multiple regression analysis reveal that the most important predictors of sport participation of youth are communication about sport (β = .18, p < .001), mutual support (β = .13, p < .001), regular sport activity (β = .10, p < .01) and the importance of sport in the family (β = .10, p < .01). By means of content analysis, more in-depth information could be identified. The promotion of sport through sport-related behaviour patterns in the family appears to be a successful strategy to develop a durable sport commitment in youth. References Baur, J. (1989). Körper- und Bewegungskarrieren [Body and exercise careers]. Schorndorf: Hofmann. Burrmann, U. (2005). Zur Vermittlung und intergenerationalen "Vererbung" von Sport(vereins)engagements in der Herkunftsfamilie [On placing and "inheriting" intergenerational sport(club) commitment in the family of origin]. Sport und Gesellschaft, 2, 125–154. Hurrelmann, K. (2006). Einführung in die Sozialisationstheorie [Introduction to socialisation theory] (9th ed.). Studium Paedagogik. Weinheim: Beltz.

CD4 count at antiretroviral therapy initiation and the risk of loss to follow-up: results from a multicentre cohort study.

BACKGROUND Antiretroviral therapy (ART) initiation is now recommended irrespective of CD4 count. However data on the relationship between CD4 count at ART initiation and loss to follow-up (LTFU) are limited and conflicting. METHODS We conducted a cohort analysis including all adults initiating ART (2008-2012) at three public sector sites in South Africa. LTFU was defined as no visit in the 6 months before database closure. The Kaplan-Meier estimator and Cox's proportional hazards models examined the relationship between CD4 count at ART initiation and 24-month LTFU. Final models were adjusted for demographics, year of ART initiation, programme expansion and corrected for unascertained mortality. RESULTS Among 17 038 patients, the median CD4 at initiation increased from 119 (IQR 54-180) in 2008 to 257 (IQR 175-318) in 2012. In unadjusted models, observed LTFU was associated with both CD4 counts <100 cells/μL and CD4 counts ≥300 cells/μL. After adjustment, patients with CD4 counts ≥300 cells/μL were 1.35 (95% CI 1.12 to 1.63) times as likely to be LTFU after 24 months compared to those with a CD4 150-199 cells/μL. This increased risk for patients with CD4 counts ≥300 cells/μL was largest in the first 3 months on treatment. Correction for unascertained deaths attenuated the association between CD4 counts <100 cells/μL and LTFU while the association between CD4 counts ≥300 cells/μL and LTFU persisted. CONCLUSIONS Patients initiating ART at higher CD4 counts may be at increased risk for LTFU. With programmes initiating patients at higher CD4 counts, models of ART delivery need to be reoriented to support long-term retention.

An Economic Model of Fair Use

The doctrine of fair use allows unauthorized copying of original works of art, music, and literature for limited purposes like criticism, research, and education, based on the rationale that copyright holders would consent to such uses if bargaining were possible. This paper develops the first formal analysis of fair use in an effort to derive the efficient legal standard for applying the doctrine. The model interprets copies and originals as differentiated products and defines fair use as a threshold separating permissible copying from infringement. Application of the analysis to several key cases (including the recent Napster case) shows that this interpretation is consistent with actual legal reasoning. The analysis also underscores the role of technology in shaping the efficient scope of fair use.

Gay Parenthood and the Revolution of the Modern Family: An Examination of the Unique Barriers Confronting Gay Adoptive Parents

Abstract: In recent decades, the structure of the American family has been revolutionized to incorporate families of diverse and unconventional compositions. Gay and lesbian couples have undoubtedly played a crucial role in this revolution by establishing families through the tool of adoption. Eleven adoptive parents from the state of Connecticut were interviewed to better conceptualize the unique barriers gay couples encounter in the process adoption. Both the scholarly research and the interview data illustrate that although gay couples face enormous legal barriers, the majority of their hardship comes through social interactions. As a result, the cultural myths and legal restrictions that create social hardships for gay adoptive parents forge a vicious and discriminatory cycle of marginalization that American legal history illustrates is best remedied through judicial intervention at the Supreme Court level. While judicial intervention, alone, cannot change the reality of gay parenthood, I argue that past judicial precedent illustrates that such change can serve as a tool of individual, political, and legal validation for the gay community for obtaining equal rights.

Una articulación de arte y política : Dislocaciones y rupturas en la poética de Edgardo Antonio Vigo (1968-1975)

Esta tesis, que integra los estudios de la Sociología del Arte, se centra en la vinculación de la poética del artista Edgardo Antonio Vigo (1928 - 1997) con la política y lo político, así como con los procesos sociales más generales entre 1968 y 1975. Vigo ocupó una posición emergente en el desarrollo del arte platense y desplegó producciones que emprendieron una poética rupturista con lo establecido por algunos de los cánones tradicionales del arte y sus instituciones, y elaboró propuestas estéticas innovadoras que abarcaban las artes visuales en sus diversas formas. Se analizan en esta tesis los modos por los que Vigo al mismo tiempo que apunta a cuestionar las estructuras y manifestaciones de las Bellas Artes, lo hace con las formas dominantes de la cultura a través de obras y textos que tendían a desestabilizar los roles de autor, espectador y obra, así como a involucrarse de distintos modos en los acontecimientos políticos de la época. Se estudian, además, las producción de acciones artísticas en el espacio público, que Vigo llamó señalamientos, la utilización y apropiación del discurso y aspectos materiales de lo judicial-administrativo y la edición de la revista ensamblada Hexágono '71 (1971 -1975). En estas zonas de la poética de Vigo se consideran las diversas relaciones entre arte y política, las cuales no han sido lineales ni unidireccionales, sino modos de distorsionar y disentir con las jerarquías, lugares y funciones de los sujetos y objetos del entramado social. Para la realización de la tesis se produjo un diseño metodológico cualitativo, se utilizaron fuentes documentales y entrevistas. Se desarrolla un análisis de las obras del artista, más que remitiéndolas a una corriente artística particular, haciendo foco en su relación con la situación social y política, especialmente en sus vinculaciones con el particular proceso de subjetivación política de la época. Se procuró para ello realizar una investigación que se detenga de manera pormenorizada en el trabajo artístico y sus particularidades (materiales, técnicas, formas, estrategias de intervención), así como en sus discursos escritos, plasmados en ensayos, artículos y otros textos, para avanzar desde allí hacia un análisis interpretativo y comprensivo de las conexiones y de los efectos que perseguía tal trabajo con los procesos políticos. Se presentan en los Anexos matrices de datos de los señalamientos y de Hexágono '71, así como un índice razonado de la misma

A poetics of Marcel Proust's vocation

The view is upheld that it is possible to constitute a conception of artistic vocation from fiction itself with characteristics that may be extended to other vocational fields. "A la Recherche du Temps Perdu" by Marcel Proust is made use of to exemplify how this author reflects critically on his own work and on the artist's conditions. Thus he points out the importance of randomness, childhood, Materializing into a work an adequate conception of his own artistic work, involuntary memory, the life that has been lived, and his own comprehension of art, the force of conviction, Vocation is a call that overcomes the dichotomy between innate gift and social product as it is the result of a genesis of sensory impressions and involuntary memories that, although they are fugacious, they become fixed in the literary work. It is explained how "A la Recherche " both can and cannot be considered the history of a vocation, as literature had not played any role at all in the novelistic hero's life, but, however, it really was a history of a vocation since the work was a consequence of events that had been lived. Notwithstanding, even if vocation had never been deemed so important, he must win a battle against death. Genette sums up "A la Recherche " thus: "Marcel becomes a writer".

Una articulación de arte y política : Dislocaciones y rupturas en la poética de Edgardo Antonio Vigo (1968-1975)

Esta tesis, que integra los estudios de la Sociología del Arte, se centra en la vinculación de la poética del artista Edgardo Antonio Vigo (1928 - 1997) con la política y lo político, así como con los procesos sociales más generales entre 1968 y 1975. Vigo ocupó una posición emergente en el desarrollo del arte platense y desplegó producciones que emprendieron una poética rupturista con lo establecido por algunos de los cánones tradicionales del arte y sus instituciones, y elaboró propuestas estéticas innovadoras que abarcaban las artes visuales en sus diversas formas. Se analizan en esta tesis los modos por los que Vigo al mismo tiempo que apunta a cuestionar las estructuras y manifestaciones de las Bellas Artes, lo hace con las formas dominantes de la cultura a través de obras y textos que tendían a desestabilizar los roles de autor, espectador y obra, así como a involucrarse de distintos modos en los acontecimientos políticos de la época. Se estudian, además, las producción de acciones artísticas en el espacio público, que Vigo llamó señalamientos, la utilización y apropiación del discurso y aspectos materiales de lo judicial-administrativo y la edición de la revista ensamblada Hexágono '71 (1971 -1975). En estas zonas de la poética de Vigo se consideran las diversas relaciones entre arte y política, las cuales no han sido lineales ni unidireccionales, sino modos de distorsionar y disentir con las jerarquías, lugares y funciones de los sujetos y objetos del entramado social. Para la realización de la tesis se produjo un diseño metodológico cualitativo, se utilizaron fuentes documentales y entrevistas. Se desarrolla un análisis de las obras del artista, más que remitiéndolas a una corriente artística particular, haciendo foco en su relación con la situación social y política, especialmente en sus vinculaciones con el particular proceso de subjetivación política de la época. Se procuró para ello realizar una investigación que se detenga de manera pormenorizada en el trabajo artístico y sus particularidades (materiales, técnicas, formas, estrategias de intervención), así como en sus discursos escritos, plasmados en ensayos, artículos y otros textos, para avanzar desde allí hacia un análisis interpretativo y comprensivo de las conexiones y de los efectos que perseguía tal trabajo con los procesos políticos. Se presentan en los Anexos matrices de datos de los señalamientos y de Hexágono '71, así como un índice razonado de la misma

A poetics of Marcel Proust's vocation

The view is upheld that it is possible to constitute a conception of artistic vocation from fiction itself with characteristics that may be extended to other vocational fields. "A la Recherche du Temps Perdu" by Marcel Proust is made use of to exemplify how this author reflects critically on his own work and on the artist's conditions. Thus he points out the importance of randomness, childhood, Materializing into a work an adequate conception of his own artistic work, involuntary memory, the life that has been lived, and his own comprehension of art, the force of conviction, Vocation is a call that overcomes the dichotomy between innate gift and social product as it is the result of a genesis of sensory impressions and involuntary memories that, although they are fugacious, they become fixed in the literary work. It is explained how "A la Recherche " both can and cannot be considered the history of a vocation, as literature had not played any role at all in the novelistic hero's life, but, however, it really was a history of a vocation since the work was a consequence of events that had been lived. Notwithstanding, even if vocation had never been deemed so important, he must win a battle against death. Genette sums up "A la Recherche " thus: "Marcel becomes a writer".

Una articulación de arte y política : Dislocaciones y rupturas en la poética de Edgardo Antonio Vigo (1968-1975)

Esta tesis, que integra los estudios de la Sociología del Arte, se centra en la vinculación de la poética del artista Edgardo Antonio Vigo (1928 - 1997) con la política y lo político, así como con los procesos sociales más generales entre 1968 y 1975. Vigo ocupó una posición emergente en el desarrollo del arte platense y desplegó producciones que emprendieron una poética rupturista con lo establecido por algunos de los cánones tradicionales del arte y sus instituciones, y elaboró propuestas estéticas innovadoras que abarcaban las artes visuales en sus diversas formas. Se analizan en esta tesis los modos por los que Vigo al mismo tiempo que apunta a cuestionar las estructuras y manifestaciones de las Bellas Artes, lo hace con las formas dominantes de la cultura a través de obras y textos que tendían a desestabilizar los roles de autor, espectador y obra, así como a involucrarse de distintos modos en los acontecimientos políticos de la época. Se estudian, además, las producción de acciones artísticas en el espacio público, que Vigo llamó señalamientos, la utilización y apropiación del discurso y aspectos materiales de lo judicial-administrativo y la edición de la revista ensamblada Hexágono '71 (1971 -1975). En estas zonas de la poética de Vigo se consideran las diversas relaciones entre arte y política, las cuales no han sido lineales ni unidireccionales, sino modos de distorsionar y disentir con las jerarquías, lugares y funciones de los sujetos y objetos del entramado social. Para la realización de la tesis se produjo un diseño metodológico cualitativo, se utilizaron fuentes documentales y entrevistas. Se desarrolla un análisis de las obras del artista, más que remitiéndolas a una corriente artística particular, haciendo foco en su relación con la situación social y política, especialmente en sus vinculaciones con el particular proceso de subjetivación política de la época. Se procuró para ello realizar una investigación que se detenga de manera pormenorizada en el trabajo artístico y sus particularidades (materiales, técnicas, formas, estrategias de intervención), así como en sus discursos escritos, plasmados en ensayos, artículos y otros textos, para avanzar desde allí hacia un análisis interpretativo y comprensivo de las conexiones y de los efectos que perseguía tal trabajo con los procesos políticos. Se presentan en los Anexos matrices de datos de los señalamientos y de Hexágono '71, así como un índice razonado de la misma

A poetics of Marcel Proust's vocation

The view is upheld that it is possible to constitute a conception of artistic vocation from fiction itself with characteristics that may be extended to other vocational fields. "A la Recherche du Temps Perdu" by Marcel Proust is made use of to exemplify how this author reflects critically on his own work and on the artist's conditions. Thus he points out the importance of randomness, childhood, Materializing into a work an adequate conception of his own artistic work, involuntary memory, the life that has been lived, and his own comprehension of art, the force of conviction, Vocation is a call that overcomes the dichotomy between innate gift and social product as it is the result of a genesis of sensory impressions and involuntary memories that, although they are fugacious, they become fixed in the literary work. It is explained how "A la Recherche " both can and cannot be considered the history of a vocation, as literature had not played any role at all in the novelistic hero's life, but, however, it really was a history of a vocation since the work was a consequence of events that had been lived. Notwithstanding, even if vocation had never been deemed so important, he must win a battle against death. Genette sums up "A la Recherche " thus: "Marcel becomes a writer".

Contribution to the Analysis, Design and Assessment of Compact Antenna Test Ranges At Millimeter Wavelengths - Contribución al Análisis, Diseño y Caracterización de Sistemas de Medida de Antenas en Rango Compacto para Frecuencias Milimétricas

This Doctoral Thesis entitled Contribution to the analysis, design and assessment of compact antenna test ranges at millimeter wavelengths aims to deepen the knowledge of a particular antenna measurement system: the compact range, operating in the frequency bands of millimeter wavelengths. The thesis has been developed at Radiation Group (GR), an antenna laboratory which belongs to the Signals, Systems and Radiocommunications department (SSR), from Technical University of Madrid (UPM). The Radiation Group owns an extensive experience on antenna measurements, running at present four facilities which operate in different configurations: Gregorian compact antenna test range, spherical near field, planar near field and semianechoic arch system. The research work performed in line with this thesis contributes the knowledge of the first measurement configuration at higher frequencies, beyond the microwaves region where Radiation Group features customer-level performance. To reach this high level purpose, a set of scientific tasks were sequentially carried out. Those are succinctly described in the subsequent paragraphs. A first step dealed with the State of Art review. The study of scientific literature dealed with the analysis of measurement practices in compact antenna test ranges in addition with the particularities of millimeter wavelength technologies. Joint study of both fields of knowledge converged, when this measurement facilities are of interest, in a series of technological challenges which become serious bottlenecks at different stages: analysis, design and assessment. Thirdly after the overview study, focus was set on Electromagnetic analysis algorithms. These formulations allow to approach certain electromagnetic features of interest, such as field distribution phase or stray signal analysis of particular structures when they interact with electromagnetic waves sources. Properly operated, a CATR facility features electromagnetic waves collimation optics which are large, in terms of wavelengths. Accordingly, the electromagnetic analysis tasks introduce an extense number of mathematic unknowns which grow with frequency, following different polynomic order laws depending on the used algorithmia. In particular, the optics configuration which was of our interest consisted on the reflection type serrated edge collimator. The analysis of these devices requires a flexible handling of almost arbitrary scattering geometries, becoming this flexibility the nucleus of the algorithmia’s ability to perform the subsequent design tasks. This thesis’ contribution to this field of knowledge consisted on reaching a formulation which was powerful at the same time when dealing with various analysis geometries and computationally speaking. Two algorithmia were developed. While based on the same principle of hybridization, they reached different order Physics performance at the cost of the computational efficiency. Inter-comparison of their CATR design capabilities was performed, reaching both qualitative as well as quantitative conclusions on their scope. In third place, interest was shifted from analysis - design tasks towards range assessment. Millimetre wavelengths imply strict mechanical tolerances and fine setup adjustment. In addition, the large number of unknowns issue already faced in the analysis stage appears as well in the on chamber field probing stage. Natural decrease of dynamic range available by semiconductor millimeter waves sources requires in addition larger integration times at each probing point. These peculiarities increase exponentially the difficulty of performing assessment processes in CATR facilities beyond microwaves. The bottleneck becomes so tight that it compromises the range characterization beyond a certain limit frequency which typically lies on the lowest segment of millimeter wavelength frequencies. However the value of range assessment moves, on the contrary, towards the highest segment. This thesis contributes this technological scenario developing quiet zone probing techniques which achieves substantial data reduction ratii. Collaterally, it increases the robustness of the results to noise, which is a virtual rise of the setup’s available dynamic range. In fourth place, the environmental sensitivity of millimeter wavelengths issue was approached. It is well known the drifts of electromagnetic experiments due to the dependance of the re sults with respect to the surrounding environment. This feature relegates many industrial practices of microwave frequencies to the experimental stage, at millimeter wavelengths. In particular, evolution of the atmosphere within acceptable conditioning bounds redounds in drift phenomena which completely mask the experimental results. The contribution of this thesis on this aspect consists on modeling electrically the indoor atmosphere existing in a CATR, as a function of environmental variables which affect the range’s performance. A simple model was developed, being able to handle high level phenomena, such as feed - probe phase drift as a function of low level magnitudes easy to be sampled: relative humidity and temperature. With this model, environmental compensation can be performed and chamber conditioning is automatically extended towards higher frequencies. Therefore, the purpose of this thesis is to go further into the knowledge of millimetre wavelengths involving compact antenna test ranges. This knowledge is dosified through the sequential stages of a CATR conception, form early low level electromagnetic analysis towards the assessment of an operative facility, stages for each one of which nowadays bottleneck phenomena exist and seriously compromise the antenna measurement practices at millimeter wavelengths.

Proposal of a three level complexity model for office automation

Office automation is one of the fields where the complexity related with technologies and working environments can be best shown. This is the starting point we have chosen to build up a theoretical model that shows us a scene quite different from the one traditionally considered. Through the development of the model, the levels of complexity associated with office automation and office environments have been identified, establishing a relationship between them. Thus, the model allows to state a general principle for sociotechnical design of office automation systems, comprising the ontological distinctions needed to properly evaluate each particular technology and its virtual contribution to office automation. From this fact comes the model's taxonomic ability to draw a global perspective of the state-of-art in office automation technologies.

Development of a Uniform Theory of Diffraction for Scattered and Surface Electromagnetic Field Analysis on a Cylinder

Con esta tesis ”Desarrollo de una Teoría Uniforme de la Difracción para el Análisis de los Campos Electromagnéticos Dispersados y Superficiales sobre un Cilindro” hemos iniciado una nueva línea de investigación que trata de responder a la siguiente pregunta: ¿cuál es la impedancia de superficie que describe una estructura de conductor eléctrico perfecto (PEC) convexa recubierta por un material no conductor? Este tipo de estudios tienen interés hoy en día porque ayudan a predecir el campo electromagnético incidente, radiado o que se propaga sobre estructuras metálicas y localmente convexas que se encuentran recubiertas de algún material dieléctrico, o sobre estructuras metálicas con pérdidas, como por ejemplo se necesita en determinadas aplicaciones aeroespaciales, marítimas o automovilísticas. Además, desde un punto de vista teórico, la caracterización de la impedancia de superficie de una estructura PEC recubierta o no por un dieléctrico es una generalización de varias soluciones que tratan ambos tipos de problemas por separado. En esta tesis se desarrolla una teoría uniforme de la difracción (UTD) para analizar el problema canónico del campo electromagnético dispersado y superficial en un cilindro circular eléctricamente grande con una condición de contorno de impedancia (IBC) para frecuencias altas. Construir una solución basada en UTD para este problema canónico es crucial en el desarrollo de un método UTD para el caso más general de una superficie arbitrariamente convexa, mediante el uso del principio de localización de los campos electromagnéticos a altas frecuencias. Esta tesis doctoral se ha llevado a cabo a través de una serie de hitos que se enumeran a continuación, enfatizando las contribuciones a las que ha dado lugar. Inicialmente se realiza una revisión en profundidad del estado del arte de los métodos asintóticos con numerosas referencias. As í, cualquier lector novel puede llegar a conocer la historia de la óptica geométrica (GO) y la teoría geométrica de la difracción (GTD), que dieron lugar al desarrollo de la UTD. Después, se investiga ampliamente la UTD y los trabajos más importantes que pueden encontrarse en la literatura. As í, este capítulo, nos coloca en la posición de afirmar que, hasta donde nosotros conocemos, nadie ha intentado antes llevar a cabo una investigación rigurosa sobre la caracterización de la impedancia de superficie de una estructura PEC recubierta por un material dieléctrico, utilizando para ello la UTD. Primero, se desarrolla una UTD para el problema canónico de la dispersión electromagnética de un cilindro circular eléctricamente grande con una IBC uniforme, cuando es iluminado por una onda plana con incidencia oblicua a frecuencias altas. La solución a este problema canónico se construye a partir de una solución exacta mediante una expansión de autofunciones de propagación radial. Entonces, ésta se convierte en una nueva expansión de autofunciones de propagación circunferencial muy apropiada para cilindros grandes, a través de la transformación de Watson. De esta forma, la expresión del campo se reduce a una integral que se evalúa asintóticamente, para altas frecuencias, de manera uniforme. El resultado se expresa según el trazado de rayos descrito en la UTD. La solución es uniforme porque tiene la importante propiedad de mantenerse continua a lo largo de la región de transición, a ambos lados de la superficie del contorno de sombra. Fuera de la región de transición la solución se reduce al campo incidente y reflejado puramente ópticos en la región iluminada del cilindro, y al campo superficial difractado en la región de sombra. Debido a la IBC el campo dispersado contiene una componente contrapolar a causa de un acoplamiento entre las ondas TEz y TMz (donde z es el eje del cilindro). Esta componente contrapolar desaparece cuando la incidencia es normal al cilindro, y también en la región iluminada cuando la incidencia es oblicua donde el campo se reduce a la solución de GO. La solución UTD presenta una muy buena exactitud cuando se compara numéricamente con una solución de referencia exacta. A continuación, se desarrolla una IBC efectiva para el cálculo del campo electromagnético dispersado en un cilindro circular PEC recubierto por un dieléctrico e iluminado por una onda plana incidiendo oblicuamente. Para ello se derivan dos impedancias de superficie en relación directa con las ondas creeping y de superficie TM y TE que se excitan en un cilindro recubierto por un material no conductor. Las impedancias de superficie TM y TE están acopladas cuando la incidencia es oblicua, y dependen de la geometría del problema y de los números de onda. Además, se ha derivado una impedancia de superficie constante, aunque con diferente valor cuando el observador se encuentra en la zona iluminada o en la zona de sombra. Después, se presenta una solución UTD para el cálculo de la dispersión de una onda plana con incidencia oblicua sobre un cilindro eléctricamente grande y convexo, mediante la generalización del problema canónico correspondiente al cilindro circular. La solución asintótica es uniforme porque se mantiene continua a lo largo de la región de transición, en las inmediaciones del contorno de sombra, y se reduce a la solución de rayos ópticos en la zona iluminada y a la contribución de las ondas de superficie dentro de la zona de sombra, lejos de la región de transición. Cuando se usa cualquier material no conductor se excita una componente contrapolar que tiende a desaparecer cuando la incidencia es normal al cilindro y en la región iluminada. Se discuten ampliamente las limitaciones de las fórmulas para la impedancia de superficie efectiva, y se compara la solución UTD con otras soluciones de referencia, donde se observa una muy buena concordancia. Y en tercer lugar, se presenta una aproximación para una impedancia de superficie efectiva para el cálculo de los campos superficiales en un cilindro circular conductor recubierto por un dieléctrico. Se discuten las principales diferencias que existen entre un cilindro PEC recubierto por un dieléctrico desde un punto de vista riguroso y un cilindro con una IBC. Mientras para un cilindro de impedancia se considera una impedancia de superficie constante o uniforme, para un cilindro conductor recubierto por un dieléctrico se derivan dos impedancias de superficie. Estas impedancias de superficie están asociadas a los modos de ondas creeping TM y TE excitadas en un cilindro, y dependen de la posición y de la orientación del observador y de la fuente. Con esto en mente, se deriva una solución UTD con IBC para los campos superficiales teniendo en cuenta las dependencias de la impedancia de superficie. La expansión asintótica se realiza, mediante la transformación de Watson, sobre la representación en serie de las funciones de Green correspondientes, evitando as í calcular las derivadas de orden superior de las integrales de tipo Fock, y dando lugar a una solución rápida y precisa. En los ejemplos numéricos realizados se observa una muy buena precisión cuando el cilindro y la separación entre el observador y la fuente son grandes. Esta solución, junto con el método de los momentos (MoM), se puede aplicar para el cálculo eficiente del acoplamiento mutuo de grandes arrays conformados de antenas de parches. Los métodos propuestos basados en UTD para el cálculo del campo electromagnético dispersado y superficial sobre un cilindro PEC recubierto de dieléctrico con una IBC efectiva suponen un primer paso hacia la generalización de una solución UTD para superficies metálicas convexas arbitrarias cubiertas por un material no conductor e iluminadas por una fuente electromagnética arbitraria. ABSTRACT With this thesis ”Development of a Uniform Theory of Diffraction for Scattered and Surface Electromagnetic Field Analysis on a Cylinder” we have initiated a line of investigation whose goal is to answer the following question: what is the surface impedance which describes a perfect electric conductor (PEC) convex structure covered by a material coating? These studies are of current and future interest for predicting the electromagnetic (EM) fields incident, radiating or propagating on locally smooth convex parts of highly metallic structures with a material coating, or by a lossy metallic surfaces, as for example in aerospace, maritime and automotive applications. Moreover, from a theoretical point of view, the surface impedance characterization of PEC surfaces with or without a material coating represents a generalization of independent solutions for both type of problems. A uniform geometrical theory of diffraction (UTD) is developed in this thesis for analyzing the canonical problem of EM scattered and surface field by an electrically large circular cylinder with an impedance boundary condition (IBC) in the high frequency regime, by means of a surface impedance characterization. The construction of a UTD solution for this canonical problem is crucial for the development of the corresponding UTD solution for the more general case of an arbitrary smooth convex surface, via the principle of the localization of high frequency EM fields. The development of the present doctoral thesis has been carried out through a series of landmarks that are enumerated as follows, emphasizing the main contributions that this work has given rise to. Initially, a profound revision is made in the state of art of asymptotic methods where numerous references are given. Thus, any reader may know the history of geometrical optics (GO) and geometrical theory of diffraction (GTD), which led to the development of UTD. Then, the UTD is deeply investigated and the main studies which are found in the literature are shown. This chapter situates us in the position to state that, as far as we know, nobody has attempted before to perform a rigorous research about the surface impedance characterization for material-coated PEC convex structures via UTD. First, a UTD solution is developed for the canonical problem of the EM scattering by an electrically large circular cylinder with a uniform IBC, when it is illuminated by an obliquely incident high frequency plane wave. A solution to this canonical problem is first constructed in terms of an exact formulation involving a radially propagating eigenfunction expansion. The latter is converted into a circumferentially propagating eigenfunction expansion suited for large cylinders, via the Watson transformation, which is expressed as an integral that is subsequently evaluated asymptotically, for high frequencies, in a uniform manner. The resulting solution is then expressed in the desired UTD ray form. This solution is uniform in the sense that it has the important property that it remains continuous across the transition region on either side of the surface shadow boundary. Outside the shadow boundary transition region it recovers the purely ray optical incident and reflected ray fields on the deep lit side of the shadow boundary and to the modal surface diffracted ray fields on the deep shadow side. The scattered field is seen to have a cross-polarized component due to the coupling between the TEz and TMz waves (where z is the cylinder axis) resulting from the IBC. Such cross-polarization vanishes for normal incidence on the cylinder, and also in the deep lit region for oblique incidence where it properly reduces to the GO or ray optical solution. This UTD solution is shown to be very accurate by a numerical comparison with an exact reference solution. Then, an effective IBC is developed for the EM scattered field on a coated PEC circular cylinder illuminated by an obliquely incident plane wave. Two surface impedances are derived in a direct relation with the TM and TE surface and creeping wave modes excited on a coated cylinder. The TM and TE surface impedances are coupled at oblique incidence, and depend on the geometry of the problem and the wave numbers. Nevertheless, a constant surface impedance is found, although with a different value when the observation point lays in the lit or in the shadow region. Then, a UTD solution for the scattering of an obliquely incident plane wave on an electrically large smooth convex coated PEC cylinder is introduced, via a generalization of the canonical circular cylinder problem. The asymptotic solution is uniform because it remains continuous across the transition region, in the vicinity of the shadow boundary, and it recovers the ray optical solution in the deep lit region and the creeping wave formulation within the deep shadow region. When a coating is present a cross-polar field term is excited, which vanishes at normal incidence and in the deep lit region. The limitations of the effective surface impedance formulas are discussed, and the UTD solution is compared with some reference solutions where a very good agreement is met. And in third place, an effective surface impedance approach is introduced for determining surface fields on an electrically large coated metallic circular cylinder. Differences in analysis of rigorouslytreated coated metallic cylinders and cylinders with an IBC are discussed. While for the impedance cylinder case a single constant or uniform surface impedance is considered, for the coated metallic cylinder case two surface impedances are derived. These are associated with the TM and TE creeping wave modes excited on a cylinder and depend on observation and source positions and orientations. With this in mind, a UTD based method with IBC is derived for the surface fields by taking into account the surface impedance variation. The asymptotic expansion is performed, via the Watson transformation, over the appropriate series representation of the Green’s functions, thus avoiding higher-order derivatives of Fock-type integrals, and yielding a fast and an accurate solution. Numerical examples reveal a very good accuracy for large cylinders when the separation between the observation and the source point is large. Thus, this solution could be efficiently applied in mutual coupling analysis, along with the method of moments (MoM), of large conformal microstrip array antennas. The proposed UTD methods for scattered and surface EM field analysis on a coated PEC cylinder with an effective IBC are considered the first steps toward the generalization of a UTD solution for large arbitrarily convex smooth metallic surfaces covered by a material coating and illuminated by an arbitrary EM source.

Urbanism and dictatorship: perspectives of the field of urban studies

In 1933 public letter to Wilhelm Furtwängler, Joseph Goebbels synthesized the official understanding of the link between politics, art and society in the early steps of the Third Reich. By assuming the ethos of art, politics acquired a plastic agency to mold its objects —population and the state— as a unified entity in the form of a ‘national-popular community’ (Volksgemeinschaft); in turn, by infusing art with a political valence, it became part of a wider governmental apparatus that reshaped aesthetic discourses and practices. Similar remarks could be made about the ordering of cities and territories in this period. Dictatorial imaginations mobilized urbanism —including urban theory, urban design and planning— as a fundamental tool for social organization. Under their aegis the production of space became a moment in a wider production of society. Many authors suggest that this political-spatial nexus is intrinsic to modernity itself, beyond dictatorial regimes. In this light, I propose to use dictatorial urbanisms as an analytical opportunity to delve into some concealed features of modern urban design and planning. This chapter explores some of these aspects from a theoretical standpoint, focusing on the development of dictatorial planning mentalities and spatial rationalities and drawing links to other historical episodes in order to inscribe the former in a broader genealogy of urbanism. Needless to say, I don’t suggest that we use dictatorships as mere templates to understand modern productions of space. Instead, these cases provide a crude version of some fundamental drives in the operationalization of urbanism as an instrument of social regulation, showing how far the modern imagination of sociospatial orderings can go. Dictatorial urbanisms constituted a set of experiences where many dreams and aspirations of modern planning went to die. But not, as the conventional account would have it, because the former were the antithesis of the latter, but rather because they worked as the excess of a particular orientation of modern spatial governmentalities — namely, their focus on calculation, social engineering and disciplinary spatialities, and their attempt to subsume a wide range of everyday practices under institutional structuration by means of spatial mediations. In my opinion the interest of dictatorial urbanisms lies in their role as key regulatory episodes in a longer history of our urban present. They stand as a threshold between the advent of planning in the late 19th and early 20th century, and its final consolidation as a crucial state instrument after World War II. We need, therefore, to pay attention to these experiences vis-à-vis the alleged ‘normal’ development of the field in contemporary democratic countries in order to develop a full comprehension thereof.