Micro-mechanical modelling of lenght distributions in short fibre reinforced composites

The material behaviour of short fibre reinforced composites is dependent on several micro-structural properties, such as the fibre orientation distribution and the geometrical fibre properties. Hence, in order to accurately predict the mechanical response of these materials, micro-mechanical models are used. Those models estimate a homogenised material response for these rather heterogeneous materials. The length of the short fibres inside the composite is not uniform due to the manufacturing process of these materials. Hence, it is necessary to represent the distribution of fibre lengths inside a composite within the micro-mechanical model. In this work, a two-step Orientation Averaging model is extended to account for fibre length distributions for the linear elastic and elasto-plastic material behaviour. Three different methods for modelling the fibre length distributions are investigated and compared. Two of them are then implemented for further investigations. The first method uses Unit Cell simulations for different fibre length classes, which are combined to a composite behaviour in an additional averaging scheme. For the second method, a single representative fibre length is obtained from the fibre length distribution, and the two-step Orientation Averaging is applied with this single fibre length. For that, a novel method for a representative fibre length is presented with the stiffness-averaged fibre length. The predictions obtained with the models show good agreement with the experimental results as well as in comparison to each other. Due to the better computational performance, the method using a single representative fibre length is preferred and recommended for the ongoing investigations

What Drives Fiscal Multipliers? The Role of Private Wealth and Debt

We show that fiscal multiplier estimations may be biased by movements in asset and credit markets, as they facilitate spurious correlations of changes in cyclically adjusted revenues and spending with GDP growth via wrong identifications and an omitted variable bias, thus overstating episodes of expansionary consolidations and downplaying contractionary consolidations. When controlling for asset and credit market movements in otherwise standard approaches to identification, we find multipliers to increase on average by 0.3 to 0.6 units. Consolidations are thus more likely to be contractionary and more harmful to growth than expected by some strands of the existing literature

Vertikale und horizontale Ungleichheiten am Übergang in die tertiäre Bildung - Unterschiede nach dem Migrationshintergrund und der sozialen Herkunft -

Social and migration-specific differences at the transition from school to higher education or vocational training as well as within post-school educational pathways form the starting point of this publication-based dissertation. Using data from DZHW Panel Study of School Leavers with a Higher Education Entrance Qualification, four articles examine how group-specific differences in the decision for or against studying occur and can be explained by performance-based as well as decision-based effects (Boudon 1974). Both, the choice of vocational training considering occupational segmentation according to school education, and migration-specific differences in the choice of field of study are subjected to initial empirical tests. The first article addresses the question how differences at the transition to tertiary education due to social origin can be explained. Employing logistic regression and decomposition analysis, it investigates the explanatory contribution of the various mechanisms identified at the theoretical level to the social differences in the likelihood of studying. The results show that the differences are mainly mediated by different decision-making behavior – almost a quarter is due to socially divergent cost estimates. Taking into account all theoretically derived mechanisms, the social differences can be completely "explained away". Since not all students take up studies, the second article considers the aspect of the choice of vocational training. It examines which factors play a role in the aspiration for an occupation that is atypical for those with university entrance qualifications. Using logistic regression analyses, the significance of the students' self-assessed strengths and career goals is highlighted. Contrary to theoretical considerations, female students with an academic background more often pursue occupations that are atypical for their school-leaving qualifications than female students without an academic background. The third article is centred around migration-specific differences at the transition to higher education. It represents a replication and analytical extension of the findings of Kristen, Reimer, and Kogan (2008). The logistic regression analyses show that the findings of Kristen et al. (2008) can be confirmed with more recent data and an appropriate operationalization of the migration background. On average, students with a migration background more often decide to take up studies compared to students without a migration background. However, even when controlling for all theoretically derived factors, the question of how these differences can be explained remains unresolved. The fourth and final article focuses on the choice of a field of study. It questions whether the high educational aspirations of students with a migration background carries on in this decision. The multinomial logistic regressions show that low-prestige subject groups are chosen less often by students with a migration background compared to students without a migration background. Moreover, students of Turkish origin are more likely than others to study a prestigious subject. The latter can be partly explained by the immigrant-optimism-hypothesis.Den Ausgangspunkt der vorliegenden publikationsbasierten Dissertation bilden soziale und migrationsspezifische Unterschiede am Übergang von der Schule in Studium oder Berufsausbildung sowie innerhalb der nachschulischen Bildungswege. In vier Beiträgen wird mit Daten des Studienberechtigtenpanels des Deutschen Zentrums für Hochschul- und Wissenschaftsforschung untersucht, wie sich die gruppenspezifischen Unterschiede bei der Entscheidung für oder gegen das Studium abzeichnen und durch leistungs- sowie entscheidungsbasierte Effekte (Boudon 1974) erklären lassen. Die Berufsausbildungwahl unter Berücksichtigung der Berufssegmentation nach schulischer Bildung und migrationsspezifische Unterschiede bei der Studienfachwahl werden hierbei ersten empirischen Tests unterzogen. Der erste Beitrag geht der Frage nach, wie sich die sozialen Herkunftsunterschiede am Übergang in die tertiäre Bildung erklären lassen. Mittels logistischer Regression und Dekompositionsanalyse wird hierbei untersucht, welchen Erklärungsbeitrag die verschiedenen auf theoretischer Ebene identifizierten Wirkmechanismen zur sozial unterschiedlichen Studierwahrscheinlichkeit beitragen. Die Ergebnisse zeigen, dass die Unterschiede vor allem über ein unterschiedliches Entscheidungsverhalten vermittelt werden – fast ein Viertel ist auf sozial divergierende Kosteneinschätzungen zurückzuführen. Unter Berücksichtigung aller theoretisch hergeleiteten Mechanismen lassen sich die sozialen Unterschiede komplett „wegerklären“. In Anbetracht der Tatsache, dass nicht alle Studienberechtigte ein Studium aufnehmen, beleuchtet der zweite Beitrag den Aspekt der Berufsausbildungswahl. Dabei wird untersucht, welche Faktoren bei der Aspiration eines für Studienberechtigte untypischen Ausbildungsberufs eine Rolle spielen. Mithilfe logistischer Regressionsanalysen kann hierbei die Bedeutung der selbsteingeschätzten Stärken und Berufsziele der Schüler*innen herausgestellt werden. Entgegen theoretischen Überlegungen streben zudem Schülerinnen mit akademischem Hintergrund häufiger als Schülerinnen ohne akademischen Hintergrund Ausbildungsberufe an, die untypisch für ihren Schulabschluss sind. Der dritte Beitrag beschäftigt sich mit migrationsspezifischen Unterschieden am Übergang in die tertiäre Bildung. Er stellt eine Replikation und analytische Erweiterung der Ergebnisse von Kristen, Reimer und Kogan (2008) dar. Die logistischen Regressionsanalysen zeigen, dass sich die Befunde von Kristen et al. (2008) mit aktuelleren Daten und angemessener Operationalisierung des Migrationshintergrunds bestätigen lassen. Studienberechtigte mit Migrationshintergrund entscheiden sich im Schnitt häufiger für ein Studium als Studienberechtigte ohne Migrationshintergrund. Die Frage nach der Erklärung dieser Unterschiede bleibt jedoch auch bei Kontrolle aller theoretisch hergeleiteter Faktoren offen. Der vierte und letzte Beitrag wendet sich der Studienfachwahl zu und hinterfragt, ob sich die hohe Bildungsaspiration der Studienberechtigten mit Migrationshintergrund bei dieser Entscheidung fortsetzt. Die multinomialen logistischen Regressionen veranschaulichen, dass prestigearme Studienfachgruppen von Studienberechtigten mit Migrationshintergrund seltener gewählt werden als von Studienberechtigten ohne Migrationshintergrund. Türkeistämmige Studienberechtigte nehmen zudem häufiger als andere das Studium eines prestigereichen Fachs auf. Letzteres lässt sich teilweise durch die Immigrant-Optimism-Hypothese erklären

Molding Minds: The Roman Use of the Cuirassed Statue in Defining Empire

Though a Roman emperor possessed a wide variety of media on which he could address his subjects- coins, arches, decrees- one of the most presently understudied is that of the cuirassed statue. In this artistic genre, the emperor was portrayed in the guise of a triumphant general while performing an adlocutio or simply holding a spear or globe to signify imperial global hegemony. Though the gesture of the ruler is certainly important, in the present study I am examining the function of the face of the breastplate as it concerns imperial propaganda. On this stone canvass the artist carved messages that enabled an emperor to advertise his latest military victory while subtly directing the thoughts of his subjects in regards to how they viewed both their own unique place within the empire and the barbaric "others" outside of it. In particular, the image of the demoralized and defeated barbarian was an especially popular and potent device utilized by many emperors to commemorate a specific victory. Through the agency of the cuirass, for example, citizens in Gaul learned of the subjugation of Judea; a land that was far removed geographically and likely not a part of their conception of the world; that is, until the emperor brought both knowledge of his victory and images of this alien people to their collective psyches. Thus, the narrative on the cuirass shaped how the Gauls viewed the emperor, the empire, and the distant peoples who challenged Rome. By examining important works within the genre and with a keen eye towards historical contexts and modern theoretical approaches, I hope to come to a fuller understanding of the ways in which a ruler strived to construct the opinions and memories of his subjects.No embarg

Beeinflusst die Qualität der Lokalen Infiltrationsanästhesie (LIA) den Behandlungsverlauf und das Behandlungsergebnis nach Kniegelenksendoprothese?

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Doctor Honoris Causa Póstuma para o Irmão Marino Latore Ariño

La solemnidad de la más alta distinción que otorga una Universidad a una autoridad académica en reconocimiento a sus méritos, en sí misma, es un hecho histórico. Sin embargo, este acto adquiere un significado aún mayor dadas las circunstancias: un homenaje póstumo, en memoria de nuestro estimado Hermano, el Dr. Marino. El Hermano Marino combinó las cualidades de docente, investigador, gran líder y educador marista, reconocido por sus competencias profesionales y socioemocionales y por su constante presencia en foros internacionales en el campo de la Educación Superior. ¡Sin duda, fue una inspiración para muchas personas! Un hombre que siempre supo compartir conocimientos; al fin y al cabo, ¿de qué serviría el conocimiento acumulado sin estar al servicio de los demás? Este es el factor distintivo de nuestro homenajeado. Que su legado nos fortalezca para ser una verdadera comunidad: una experiencia de pertenencia, como somos en comunidad cada vez que nos encontramos en un lugar al que pertenecemos. Es ese sentimiento de que somos parte de algo que es más grande que nosotros. Es la actitud de estar presente y encontrar el propósito más profundo en todo lo que hacemos. Es la sensación de seguridad que proviene de un lugar donde nos sentimos completos emocional, espiritual y psicologicamente. Fue alrededor de la comunidad académica que el Hno. Marino construyó su história y nos deja un gran y significativo legado.A solenidade para aquela que é a máxima distinção concedida por uma Universidade a uma autoridade acadêmica como reconhecimento de seus méritos, por si só, trata-se de um acontecimento histórico. Porém, este ato se reveste de um sentido ainda maior dada a circunstância: uma homenagem póstuma, em memória do nosso estimado Irmão, Dr. Marino. Ir. Marino reuniu as qualidades de professor, investigador, grande líder e educador marista, reconhecido por suas competências profissionais e socioemocionais e por sua presença constante em fóruns internacionais no âmbito da Educação Superior. Sem dúvida, foi inspiração para muitas pessoas! Um homem que sempre soube compartilhar o conhecimento; afinal, de que adiantaria o conhecimento acumulado sem que estivesse a serviço do próximo? Eis o fator distintivo do nosso homenageado. Que o seu legado nos fortaleça, para sermos uma verdadeira comunidade: uma experiência de pertença, pois estamos em comunidade cada vez que nos encontramos num lugar ao qual pertencemos. É aquele sentimento de que fazemos parte de algo que é maior do que nós. É a atitude de estar presente e encontrar o propósito mais profundo em tudo o que fazemos. É a sensação de segurança que surge de um lugar no qual nos sentimos emocionalmente, espiritualmente e psicologicamente inteiros. Foi em torno da comunidade acadêmica que o Ir. Marino construiu sua história e nos deixa um grande e significativo legado

O Simples comparado aos outros métodos tributários para uma microempresa comercial

O Simples Nacional é um sistema tributário que foi criado em 2006 através da Lei complementar nº 123 e seu objetivo é atender as micro e pequenas empresas no Brasil com uma tributação reduzida e simplificada. Este trabalho objetiva verificar se o Simples Nacional se constitui na melhor escolha tributaria para uma empresa do ramo do varejo calçadista, comparando este as outras formas de tributação aplicáveis as empresas neste ramo de negócio. O trabalho quanto aos objetivos segue os moldes de pesquisa exploratória e quanto aos procedimentos, segue os moldes de um estudo de caso.The “Simples Nacional” is a tax system that was created in 2006 by Complementary Law No. 123 and its purpose is to serve micro and small enterprises in Brazil with a reduced and simplified taxation. This Course completion assignment works on the issue as far as these assumptions are actually analyzing if “Simples Nacional” would be the best tributary choice for a shoe shop comparing this to other forms of taxation applicable to companies on this trade. This work on the objectives is patterned exploratory research and regarding procedures, work material by following the lines of a case study

Micromechanical modelling of short fibre composites considering fibre length distributions

Mechanical response of short fibre composites is varying locally with respect to the microstructural constitution of the material, which in turn is a consequence of flow conditions during manufacturing. This local constitution is described by local fibre volume content, local fibre orientation distribution and local fibre length distribution. For short fibre reinforced plastics, both distributions are affected by flow conditions during an injection moulding process. Current material models for predicting the homogenised material response account for the local volume fraction and local fibre orientation distribution. Fibre length distribution, however, is usually approximated with a single average fibre length. To investigate the effects of fibre length distribution on the elasto-plastic response of short fibre composites, a micromechanical Orientation Averaging model has been extended. Two methods are presented in this work. In the first method, an additional averaging scheme over the fibre length distribution is included. In the second method, a novel representative fibre length is presented based on a stiffness-weighted average. The predictionsobtained from these methods are then compared and evaluated against experimental results of uniaxial tensile tests taken from literature. Good agreements are found using both methods. However, for the investigated behaviour, using a representative fibre length is still beneficial due to the superior computational performance

Effects of site‐selection bias on estimates of biodiversity change

Estimates of biodiversity change are essential for the management and conservation of ecosystems. Accurate estimates rely on selecting representative sites, but monitoring often focuses on sites of special interest. How such site‐selection biases influence estimates of biodiversity change is largely unknown. Site‐selection bias potentially occurs across four major sources of biodiversity data, decreasing in likelihood from citizen science, museums, national park monitoring, and academic research. We defined site‐selection bias as a preference for sites that are either densely populated (i.e., abundance bias) or species rich (i.e., richness bias). We simulated biodiversity change in a virtual landscape and tracked the observed biodiversity at a sampled site. The site was selected either randomly or with a site‐selection bias. We used a simple spatially resolved, individual‐based model to predict the movement or dispersal of individuals in and out of the chosen sampling site. Site‐selection bias exaggerated estimates of biodiversity loss in sites selected with a bias by on average 300–400% compared with randomly selected sites. Based on our simulations, site‐selection bias resulted in positive trends being estimated as negative trends: richness increase was estimated as 0.1 in randomly selected sites, whereas sites selected with a bias showed a richness change of −0.1 to −0.2 on average. Thus, site‐selection bias may falsely indicate decreases in biodiversity. We varied sampling design and characteristics of the species and found that site‐selection biases were strongest in short time series, for small grains, organisms with low dispersal ability, large regional species pools, and strong spatial aggregation. Based on these findings, to minimize site‐selection bias, we recommend use of systematic site‐selection schemes; maximizing sampling area; calculating biodiversity measures cumulatively across plots; and use of biodiversity measures that are less sensitive to rare species, such as the effective number of species. Awareness of the potential impact of site‐selection bias is needed for biodiversity monitoring, the design of new studies on biodiversity change, and the interpretation of existing data

Overexpression of human DKK1 via rAAV vector-mediated gene transfer stimulates chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells

Enhancing the chondroregenerative activities of mesenchymal stem cells via therapeutic gene transfer as reinforced sources of implantable cells in sites of cartilage injury is a promising tool to improve the natural processes of cartilage repair. In the present study, we show that overexpression of the Dickkopf-related protein 1 (DKK1) via clinically adapted recombinant adeno-associated viral (rAAV) vectors is capable of significantly stimulating proliferative, anabolic, and chondrodifferentiation events in primary human mesenchymal stem cells compared with control (reporter rAAV lacZ) transduction over an extended period of time in vitro (21 days). Strikingly, administration of the rAAV DKK1 candidate vector concomitantly restrained unwanted osteogenic and hypertrophic differentiation outcomes in these cells. These findings reveal the possible future benefits of such an approach to treat articular cartilage lesions in relevant experimental models in vivo