Segregation unter Stagnationsbedingungen

Anlass der Untersuchung sind Verstärkungen von strukturwandel- und globalisierungsbedingten Wandlungen unter Schrumpfungs- und Stagnationsbedingungen. Denn Stagnations- und Schrumpfungstendenzen in einer Region sind selektiv, sie begünstigen über verschiedene Mechanismen Polarisierungen und Marginalisierungen: Die allgemeine Entspannung am Wohnungsmarkt hat erhöhte Mobilität und damit sozialräumliche Segregierungen und Polarisierungen der Wohnungsversorgung zur Folge. Leerstände und ausbleibende Investitionen begünstigen Polarisierungen von baulich-räumlichen Qualitäten. Diese beiden Entwicklungen überlagern sich im Stadtraum und verstärken sich gegenseitig. Dabei verbessert sich die Wohnungsversorgung in den benachteiligten Quartieren kaum, so die Ausgangshypothesen. Die Untersuchung fragt nach den Wirkungen des Nebeneinanders von Wachstums-, Stagnations- und Schrumpfungserscheinungen auf unterschiedlichen Maßstabsebenen, dem Zusammenspiel von sozialstrukturellen und qualitativen Veränderungen der baulich-räumlichen Gegebenheiten in den Quartieren sowie in innerstädtischer Differenzierung. Dabei interessieren besonders die Einflüsse eines regional entspannten Wohnungsmarktes und dessen Folgen für die Verwertungsstrategien im Wohnungsbestand auf Segregationsprozesse und die Wohnungsversorgung. Als Fallbeispiel der Untersuchung dient die Stadt Kassel. Der sozialräumliche Fokus liegt auf drei Typen benachteiligter Quartiere: Neben den in der aktuellen Diskussion zumeist betrachteten gründerzeitlichen Arbeiterquartieren und den Großsiedlungen der 1960/70er Jahre wurden auch die peripheren Geschosswohnungsbausiedlungen der 1950er/60er Jahre in die Untersuchung einbezogen, um den unterschiedlichen Rahmenbedingungen und Wirkungen in den Quartierstypen auf die Spur zu kommen und damit letztlich Grundlagen für stadtentwicklungspolitische Strategien zu erarbeiten. Die kleinräumigen Analysen von sozialräumlicher und baulich-räumlicher Struktur sowie zur Wohnungsversorgung deckten Parallelen und gegenläufige Entwicklungen zwischen den unterschiedlichen Quartierstypen auf; es ergaben sich verschiedene Anhaltspunkte zur Erhärtung der Ausgangsthesen. So wurde z.B. deutlich, dass sich unter den Marktbedingungen stagnierender Städte die Wohnflächenversorgung in den benachteiligten Quartieren kaum verbessert. Hierin zeigt sich ein entscheidender Unterschied zu stark schrumpfenden Städten, in denen sich die Versorgungslage (fast) durchgängig verbessert. Wohnungsmarktbarrieren wirken offensichtlich unter Stagnationsbedingungen für bestimmte Bevölkerungsgruppen weiter. Da sich ihre Wirkung aber für weitere Kreise der Bevölkerung abschwächt, verschärfen sich sozialräumliche Konzentrationen. Vor allem aber wurden Überlagerung und gegenseitige Verstärkung dieser sozialräumlichen mit baulich-räumlichen Polarisierungen deutlich, die vor allem aus stadträumlich konzentrierten Investitionen in den Gebäude- und Wohnungsbestand resultieren. Letztlich zeigt sich damit, dass regulierende Eingriffe nicht nur im Rahmen des Umbaus und der Erneuerung der Quartiere erforderlich sind, sondern insbesondere auch in den Wohnungsmarkt und dies auch bei entspannter regionaler Marktlage. Andernfalls ist weder eine angemessene Wohnungsversorgung aller Bevölkerungsgruppen noch der Zusammenhalt der Stadt(Gesellschaft) zu gewährleisten. Dabei ist die Stadtpolitik permanent mit der Gleichzeitigkeit von (wirtschaftlicher) Standortpolitik und sozialer Stadtentwicklung konfrontiert, die sie im Sinne einer nachhaltigen Entwicklung gegeneinander und miteinander abwägen muss.

Preparation and applications of periodical gold nanoparticle arrays

Diese Arbeit beschäftigt sich mit der Herstellung und Anwendungen von periodischen Goldnanopartikel-Arrays (PPAs), die mit Hilfe von Nanosphären-Lithografie hergestellt wurden. In Abhängigkeit der verwendeten Nanosphären-Größe wurden dabei entweder kleine dreieckige Nanopartikel (NP) (bei Verwendung von Nanosphären mit einem Durchmesser von 330 nm) oder große dreieckige NPD sowie leicht gestreckte NP (bei Verwendung von Nanosphären mit einem Durchmesser von 1390 nm) hergestellt. Die Charakterisierung der PPAs erfolgte mit Hilfe von Rasterkraftmikroskopie, Rasterelektronenmikroskopie und optischer Spektroskopie. Die kleinen NP besitzen ein Achsverhältnis (AV) von 2,47 (Kantenlänge des NPs: (74+/-6) nm, Höhe: (30+/-4) nm. Die großen dreieckigen NP haben ein AV von 3 (Kantenlänge des NPs:(465+/-27) nm, Höhe: (1530+/-10) nm) und die leicht gestreckten NP (die aufgrund der Ausbildung von Doppelschichten ebenfalls auf der gleichen Probe erzeugt wurden) haben eine Länge von (364+/-16)nm, eine Breite von (150+/-20) nm und eine Höhe von (150+/-10)nm. Die optischen Eigenschaften dieser NP werden durch lokalisierte Oberflächenplasmon-Polariton Resonanzen (LPPRs) dominiert, d.h. von einem eingestrahlten elektromagnetischen Feld angeregte kollektive Schwingungen der Leitungsbandelektronen. In dieser Arbeit wurden drei signifikante Herausforderungen für Plasmonik-Anwendungen bearbeitet, welche die einzigartigen optischen Eigenschaften dieser NP ausnutzen. Erstens wurden Ergebnisse der selektiven und präzisen Größenmanipulation und damit einer Kontrolle der interpartikulären Abstände von den dreieckigen Goldnanopartikel mit Hilfe von ns-gepulstem Laserlicht präsentiert. Die verwendete Methode basiert hierbei auf der Größen- und Formabhängigkeit der LPPRs der NP. Zweitens wurde die sensorischen Fähigkeiten von Gold-NP ausgenutzt, um die Bildung von molekularen Drähten auf den PPAs durch schrittweise Zugabe von unterschiedlichen molekularen Spezies zu untersuchen. Hierbei wurde die Verschiebung der LSPPR in den optischen Spektren dazu ausgenutzt, die Bildung der Nanodrähte zu überwachen. Drittens wurden Experimente vorgestellt, die sich die lokale Feldverstärkung von NP zu nutze machen, um eine hochgeordnete Nanostrukturierung von Oberflächen mittels fs-gepulstem Laserlicht zu bewerkstelligen. Dabei zeigt sich, dass neben der verwendeten Fluenz die Polarisationsrichtung des eingestrahlten Laserlichts in Bezug zu der NP-Orientierung sowie die Größe der NP äußerst wichtige Parameter für die Nanostrukturierung darstellen. So konnten z.B. Nanolöcher erzeugt werden, die bei höheren Fluenzen zu Nanogräben und Nanokanälen zusammen wuchsen. Zusammengefasst lässt sich sagen, dass die in dieser Arbeit gewonnen Ergebnisse von enormer Wichtigkeit für weitere Anwendungen sind.

Magnetic interactions between transition metal impurities and clusters mediated by low-dimensional metallic hosts: A first principles theoretical investigation

The magnetic properties and interactions between transition metal (TM) impurities and clusters in low-dimensional metallic hosts are studied using a first principles theoretical method. In the first part of this work, the effect of magnetic order in 3d-5d systems is addressed from the perspective of its influence on the enhancement of the magnetic anisotropy energy (MAE). In the second part, the possibility of using external electric fields (EFs) to control the magnetic properties and interactions between nanoparticles deposited at noble metal surfaces is investigated. The influence of 3d composition and magnetic order on the spin polarization of the substrate and its consequences on the MAE are analyzed for the case of 3d impurities in one- and two-dimensional polarizable hosts. It is shown that the MAE and easy- axis of monoatomic free standing 3d-Pt wires is mainly determined by the atomic spin-orbit (SO) coupling contributions. The competition between ferromagnetic (FM) and antiferromagnetic (AF) order in FePtn wires is studied in detail for n=1-4 as a function of the relative position between Fe atoms. Our results show an oscillatory behavior of the magnetic polarization of Pt atoms as a function of their distance from the magnetic impurities, which can be correlated to a long-ranged magnetic coupling of the Fe atoms. Exceptionally large variations of the induced spin and orbital moments at the Pt atoms are found as a function of concentration and magnetic order. Along with a violation of the third Hund’s rule at the Fe sites, these variations result in a non trivial behavior of the MAE. In the case of TM impurities and dimers at the Cu(111), the effects of surface charging and applied EFs on the magnetic properties and substrate-mediated magnetic interactions have been investigated. The modifications of the surface electronic structure, impurity local moments and magnetic exchange coupling as a result of the EF-induced metallic screening and charge rearrangements are analysed. In a first study, the properties of surface substitutional Co and Fe impurities are investigated as a function of the external charge per surface atom q. At large inter-impurity distances the effective magnetic exchange coupling ∆E between impurities shows RKKY-like oscillations as a function of the distance which are not significantly affected by the considered values of q. For distances r < 10 Å, important modifications in the magnitude of ∆E, involving changes from FM to AF coupling, are found depending non-monotonously on the value and polarity of q. The interaction energies are analysed from a local perspective. In a second study, the interplay between external EF effects, internal magnetic order and substrate-mediated magnetic coupling has been investigated for Mn dimers on Cu(111). Our calculations show that EF (∼ 1eV/Å) can induce a switching from AF to FM ground-state magnetic order within single Mn dimers. The relative coupling between a pair of dimers also shows RKKY-like oscillations as a function of the inter-dimer distance. Their effective magnetic exchange interaction is found to depend significantly on the magnetic order within the Mn dimers and on their relative orientation on the surface. The dependence of the substrate-mediated interaction on the magnetic state of the dimers is qualitatively explained in terms of the differences in the scattering of surface electrons. At short inter-dimer distances, the ground-state configuration is determined by an interplay between exchange interactions and EF effects. These results demonstrate that external surface charging and applied EFs offer remarkable possibilities of manipulating the sign and strength of the magnetic coupling of surface supported nanoparticles.

Femtosecond wavepacket interferometry using the rotational dynamics of a trapped cold molecular ion

A Ramsey-type interferometer is suggested, employing a cold trapped ion and two time-delayed offresonant femtosecond laser pulses. The laser light couples to the molecular polarization anisotropy, inducing rotational wavepacket dynamics. An interferogram is obtained from the delay dependent populations of the final field-free rotational states. Current experimental capabilities for cooling and preparation of the initial state are found to yield an interferogram visibility of more than 80%. The interferograms can be used to determine the polarizability anisotropy with an accuracy of about ±2%, respectively ±5%, provided the uncertainty in the initial populations and measurement errors are confined to within the same limits.

A Vector Signal Processing Approach to Color

Surface (Lambertain) color is a useful visual cue for analyzing material composition of scenes. This thesis adopts a signal processing approach to color vision. It represents color images as fields of 3D vectors, from which we extract region and boundary information. The first problem we face is one of secondary imaging effects that makes image color different from surface color. We demonstrate a simple but effective polarization based technique that corrects for these effects. We then propose a systematic approach of scalarizing color, that allows us to augment classical image processing tools and concepts for multi-dimensional color signals.

Review of bio-particle manipulation using dielectrophoresis

During the last decade, large and costly instruments are being replaced by system based on microfluidic devices. Microfluidic devices hold the promise of combining a small analytical laboratory onto a chip-sized substrate to identify, immobilize, separate, and purify cells, bio-molecules, toxins, and other chemical and biological materials. Compared to conventional instruments, microfluidic devices would perform these tasks faster with higher sensitivity and efficiency, and greater affordability. Dielectrophoresis is one of the enabling technologies for these devices. It exploits the differences in particle dielectric properties to allow manipulation and characterization of particles suspended in a fluidic medium. Particles can be trapped or moved between regions of high or low electric fields due to the polarization effects in non-uniform electric fields. By varying the applied electric field frequency, the magnitude and direction of the dielectrophoretic force on the particle can be controlled. Dielectrophoresis has been successfully demonstrated in the separation, transportation, trapping, and sorting of various biological particles.

A Modest Proposal to Clarify the Status of Coca in the United Nations Conventions

The implementation of anti-drug policies that focus on illicit crops in the Andean countries faces many significant obstacles, one of which is the cultural clash it generates between the main stakeholders. On the one hand one finds the governments and agencies that attempt to implement crop substitution and eradication policies and on the other the peasant and natives communities that have traditionally grown and used coca or those peasants who have found in coca an instrument of power and political leverage that they never had before. The confrontation about coca eradication, alternative development and other anti-drug policies in coca growing areas transcends drug related issues and is part of a wider and deeper confrontation that reflects the long-term unsolved conflicts of the Andean societies. All Andean countries have stratified and fragmented societies in which peasants and Indians have been excluded from power. In Bolivia, Ecuador and Peru most peasants belong to native communities many of which have remained segregated from “white” society. The mixing of the races (mestizaje) in Colombia occurred early during the Conquest and Colony. Those of Indian descent became subservient to the Spanish and Creoles. The society that evolved was (and still is) highly hierarchical, authoritarian, and has subjacent racist values. The resulting political system has been exclusionary of large portions of the population. Among Indian communities coca has been used for millennia and its use has become an identity symbol of their resistance against what may be looked at as foreign invasion. “The Andean Indian chews coca because that way he affirms his identity as son and owner of the land that yesterday the Spaniard took away and today the landowner keeps away from him. To chew coca is to be Indian...and to quietly and obstinately challenge the contemporary lords that descend from the old encomenderos and the older conquistadors” (Vidart, 1991: 61, author’s translation). In Andean literature on illegal drugs as well as in seminars, colloquia and other meetings where drug policies are debated, complaints are frequently expressed about the treatment of coca in the same category as cocaine, heroin, morphine amphetamines and other “hard” drugs. The complainants assert that “coca is not cocaine” and that it is unfair to classify coca, a nature given plant which has been used for millennia in the Andes without significant negative effects on users, in the same category as man made psychotropic drugs. They also argue that coca has manifold social and religious meanings in indigenous cultures, that coca is sacred and that the requirement of the1961 Single Convention demanding that Bolivia and Peru completely eradicate coca within 25 years is limiting Indigenous communities in their freedom to practice their religions. In most debates about drug interdiction, the views of those who oppose that approach are not accepted as legitimate. Indeed, “prohibitionists” demonize drugs and those who oppose drug policies in Latin America frequently demonize the United States as the imperialist power that imposes them. This dual polarization is a main obstacle to establish a meaningful policy debate aimed at broadening the policy consensus necessary for successful policy implementation. This essay surveys the status of coca in the United Nations Conventions, explains why it is confusing, and how a few changes would eliminate some of the sources of conflict and help organize and control licit coca markets in the Andes. The current disorganized and weakly controlled legal coca market in Peru has been analyzed to demonstrate its deficiencies and to illustrate possible improvements in international drug control policies.

El cierre del Canal Nacional Radio Caracas Televisión (RCTV) durante el segundo periodo de Hugo Chávez Frías, periodo 2001- 2007, como injerencia política hacia los medio audiovisuales masivos.

El estudio responde las preguntas sobre injerencia política hacia medios radioeléctricos por parte del gobierno chavecista con el cierre de RCTV; con la identificación de instrumentos jurídicos hacia los medias y la examinación en que el gobierno manejó estos instrumentos de regulación.

Análisis de la política petrolera venezolana durante el gobierno de Hugo Chávez como factor determinante de la Revolución Bolivariana (período 1999-2012)

Desde 1999, la política petrolera se constituyó como base del proyecto político chavista conocido como la Revolución Bolivariana, e incluso se convirtió en el eje de la participación, polarización y de las relaciones entre los principales actores del oficialismo y de la oposición venezolana.

La revolución como metáfora política: para una comprensión de la revolución fascista de Benito Mussolini

Asumiendo que existe una tendencia de la opinión pública y académica por relacionar la idea de revolución con procesos netamente de izquierda, se propone comprender el término como concepto y como metáfora con el fin de alejarlo de la polarización ideológica. En esta investigación se abordan los conceptos políticos y su relación con las metáforas a partir de unos principios teóricos básicos: la idea de Koselleck de que los conceptos tienen historia, y la idea de Blumenberg de que muchos conceptos fundamentales son potentes porque en el fondo son metáforas. Posteriormente se observa cómo las diferentes posturas políticas han adoptado o rechazado la idea de revolución como parte de sus proyectos políticos. Finalmente, el caso del fascismo se presenta como un escenario clave para comprobar la trascendencia del concepto y las implicaciones de su uso en términos discursivos y prácticos

The project of land restitution in Colombia: an illustration of the civilizing force of hypocrisy?

This article offers a theoretical interpretation of the dispositions on land restitution contained in the famous “Victims’ Bill”, which was debated in the Colombian Congress during the year 2008. The bill included specific mechanisms aimed at guaranteeing the restitution of land to victims of the Colombian armed conflict. At the time, the bill was endorsed by all the main political actors in the country –notably the government and the elites that support it, on the one hand, and victims’ and human rights organizations and other opposition groups, on the other–. The fact that the restitution of land to victims of the Colombian armed conflict was being considered as a serious possibility by all political actors in the country seemed to indicate the existence of a consensus among actors whose positions are ordinarily opposed, on an issue that has traditionally led to high levels of polarization. This consensus is quite puzzling, because it seems to be at odds with the interests and/or the conceptions of justice advocated by these political actors, and because the restitution of land faces enormous difficulties both from a factual and a normative point of view, which indicates that it may not necessarily be the best alternative for dealing with the issue of land distribution in Colombia. This article offers an interpretation of said consensus, arguing that it is only an apparent consensus in which the actors are actually misrepresenting their interests and conceptions of justice, while at the same time adopting divergent strategies of implementation aimed at fulfilling their true interests. Nevertheless, the article concludes that the common adherence by all actors to the principle of restorative justice might bring about its actual realization, and thus produce an outcome that, in spite (and perhaps even because) of being unintended, might substantively contribute to solving the problem of unequal land distribution in Colombia. Even though the article focuses in some detail on the specificities of the 2008 Bill, it attempts to make a general argument about the state of the discussion on how to deal with the issue of land distribution in the country. Consequently, it may still be relevant today, especially considering that a new Bill on land restitution is currently being discussed in Congress, which includes the same restitution goals as the Victims’ Bill and many of its procedural and substantive details, and which therefore seems to reflect a similar consensus to the one analyzed in the article.

Análisis del cubrimiento del periódico El Tiempo sobre la imagen de Juan Manuel Santos y Antanas Mockus en el proceso electoral colombiano llevado a cabo en el año 2010

En las noticias publicadas del 26 de febrero al 20 de junio del 2010 en el periódico El Tiempo durante la campaña electoral del año 2010, se puede ver la influencia que ejercen los medios de comunicación en las decisiones electorales de los ciudadanos. Para esto, no solo fue necesario el análisis de las noticias publicadas sino también el análisis de las encuestas y por supuesto el resultado final de la elección. Por medio de la teoría de la agenda setting se fundamenta teóricamente lo anteriormente expuesto, para poder llegar a afirmar que por diversos factores se ve una influencia en este caso del periódico El tiempo sobre un candidato especifico, Juan Manuel Santos, analizando como un medio de comunicación llega a tener cierto grado de polarización y politización donde se llega a ver un mayor cubrimiento y mejor contenido de las noticias publicadas.

Uso de la matriz extracelular como material para ingeniería de tejidos

Introducción: La evaluación de injertos vasculares de submucosa de intestino delgado para la regeneración de vasos sanguíneos ha producido una permeabilidad variable (0-100%) que ha sido concurrente con la variabilidad en las técnicas de fabricación. Metodología: Investigamos los efectos de fabricación en permeabilidad y regeneración en un diseño experimental de 22factorial que combino: 1) preservación (P) o remoción (R) de la capa estratum compactum del intestino, y 2) deshidratada (D) o hidratada (H), dentro de cuatro grupos de estudio (PD, RD, PH, RH). Los injertos fueron implantados en las Arterias Carótidas de porcinos (ID 4.5mm, N=4, 7d). Permeabilidad, trombogenicidad, reacción inflamatoria, vascularización, infiltración de fibroblastos, perfil de polarización de macrófagos y fuerza tensil biaxial fueron evaluadas. Resultados: Todos los injertos PD permanecieron permeables (4/4), pero tuvieron escasa vascularización e infiltración de fibroblastos. El grupo RD permaneció permeable (4/4), presentó una extensa vascularización e infiltración de fibroblastos, y el mayor número del fenotipo de macrófagos (M2) asociado a regeneración. El grupo RH presentó menor permeabilidad (3/4), una extensa vascularización e infiltración de fibroblastos, y un perfil dominante de M2. El grupo PH presentó el menor grado de permeabilidad, y a pesar de mayor infiltración celular que PD, exhibió un fenotipo de macrófagos dominante adverso. La elasticidad de los injertos R evolucionó de una manera similar a las Carótidas nativas (particularmente RD, mientras que los injertos P mantuvieron su rigidez inicial. Discusión: Concluimos que los parámetros de fabricación afectan drásticamente los resultados, siendo los injertos RD los que arrojaron mejores resultados.

Desigualdad y polarización del PIB por habitante en Colombia

El concepto y la medición de la polarización de una distribución han atraído la atención de los economistas en los últimos años. De manera independiente, Esteban-Ray y Wolfson han conceptualizado la noción de polarización y propuesto índices para medirla. De igual manera, Lasso de la Vega desarrolla una extensión del indicador propuesto por Esteban-Ray.Los índices de polarización tratan de estimar, dada una distribución de renta, en qué medida la población está agrupada en torno a un número de polos. Esta noción está ligada al concepto de desigualdad y surge como resultado de la deficiencia de las medidas tradicionales de desigualdad de distinguir adecuadamente entre convergencia a una media global o agrupamiento en torno a medias locales.Con este conjunto de indicadores se desarrolla una aplicación para el caso de los departamentos colombianos durante el período 1984-2004 con base en la información del PIB publicada por el Departamento Nacional de Estadística (DANE). De aquí se concluye que el proceso de desigualdad inter-regional en Colombia ha estado acompañado por una disminución de la polarización.-----The concept and measurement of the distribution polarization have appealed the economists’ attention in the past few years. Independently, Esteban- Ray and Wolfson have conceptualized the polarization notion and proposed the indices for its measurement. Similarly, Lasso de la Vega developed an extension to the indicator proposed by Esteban-Ray.Polarization indices are intended to estimate, given an income distribution, how much the population is grouped around a number of poles. This notion is linked to the concept of inequality and arises out of the traditional inequality measurements inability to properly distinguish between convergence to a global average or grouping around local averages.This suite of indicators is used on an application developed for the case of the Colombian departments in the 1984-2004 period based on the GDP data published by the Departamento Nacional de Estadística (Colombian statistics agency, DANE). The conclusion is that the cross-region inequality in Colombia has been accompanied by a polarization reduction.

The Proliferation of Paramilitary Groups in Southern Mexico: State Strategy or Struggle between Local Political Elites?

This study traces the origins of Mexican paramilitary groups and argues that, contrary to what most of the literature on the subject implies, they do not represent a state strategy to thwart leftist groups seeking social change. Rather, they represent battles between groups of national and local-level elites with different visions of democracy and of what constitutes good governance. The polarization inherent in this type of conflict leads local actors to have to side with one faction of elites or the other. The presence of radical leftist groups in recently colonized indigenous areas with scant state presence gives rise to a process of radicalization among local elites. There are multiple factors that explain the emergence of paramilitary groups. Aside from the post Cold War international context, there were national factors like a shift in its focus away from security matters between 1989 and 1993, and presidential policies between 1968 and 1993, that planted the seeds of leftist radicalism in a context of id modernization