A modular docking mechanism for in-orbit assembly and spacecraft servicing

A Docking Mechanism concept is described which is suitable for use with autonomous docking systems. The central feature of using simple cylindrical handles on one side and a type of prism seating on the other is offered as a practical method of achieving a standardized structural interface without freezing continued development of the latches, either technically or commercially. The main emphasis in docking mechanism concepts is in two directions: (1) a very simple docking mechanism, involving mainly the latch mechanism to achieve a structural link; and (2) a sophisticated Docking Mechanism, where the latch mechanism is designed for nonrigid spacecraft and the achievement of very low dynamic interactions between spacecraft during the docking process

The case for negative senescence

Negative senescence is characterized by a decline in mortality with age after reproductive maturity, generally accompanied by an increase in fecundity. Hamilton (1966) ruled out negative senescence: we adumbrate the deficiencies of his model. We review empirical studies of various plants and some kinds of animals that may experience negative senescence and conclude that negative senescence may be widespread, especially in indeterminate-growth species for which size and fertility increase with age. We develop optimization models of life-history strategies that demonstrate that negative senescence is theoretically possible. More generally, our models contribute to understanding of the evolutionary and demographic forces that mold the agetrajectories of mortality, fertility and growth.

Der Einfluss des Gens Disrupted-in-Schizophrenia 1 (DISC1) auf den Mechanismus der tangentialen Migration cortikaler Interneurone

Das Gen Disrupted-in-Schizophrenia 1 (DISC1) wurde in einer schottischen Familie entdeckt, deren Familienmitglieder eine erhöhte Prävalenz für Schizophrenie aufweisen. Aufgrund einer chromosomalen Translokation kommt es zu einer Verkürzung des Gens und damit zu einem eingeschränkt funktionsfähigen Protein. Mittlerweile gilt DISC1 als Risikogen für verschiedene psychische Erkrankungen, wie Schizophrenie oder Depression. Als ein sogenanntes Gerüstprotein zur zellulären Vermittlung von Proteinkomplexen ist es an diversen Entwicklungsprozessen, wie beispielsweise Proliferation und Migration neuronaler Zellen, im embryonalen sowie adulten Gehirn beteiligt. In dieser Arbeit wird die Rolle von DISC1 bei der tangentialen Migration cortikaler GABAerger Interneurone dargelegt. Diese Zellen werden im basalen Telencephalon geboren und wandern anschließend in den sich entwickelnden Cortex ein. Obwohl sie nur etwa 20% der neuronalen Zellen im Cortex ausmachen, stellen sie eine immense Vielfalt an physiologisch, morphologisch sowie genetisch unterschiedlichen Zellen dar und sind entscheidend an der Funktionalität des Gehirn beteiligt. Es konnte gezeigt werden, dass migrierende Interneurone DISC1 exprimieren und ein Mangel an DISC1 sowohl in vitro als auch in vivo zu Defekten bei der tangentialen Migration führt. Weitere Untersuchungen konzentrierten sich auf das Cytoskelett, durch welches die Migration realisiert wird. Während kaum ein Einfluss auf das Mikrotubuli-Cytoskelett belegt werden konnte, führt ein Mangel an DISC1 zu Veränderungen bei der Aktin-Reorganisation. Damit zeigt die vorliegende Arbeit einen möglichen Mechanismus auf, wie DISC1 auf die tangentiale Migration cortikaler Interneurone Einfluss nimmt. Diese Ergebnisse stärken die Annahme, dass Schizophrenie mit Störungen des GABAergen Systems einhergeht, und weisen darauf hin, dass es sich um eine entwicklungsbiologische Erkrankung handelt, deren Grundstein bereits während der Embryonalentwicklung gelegt wird.The gene Disrupted-in-Schizophrenia 1 (DISC1) was found in a Scottish pedigree with an increased prevalence for schizophrenia. In this family a chromosomal translocation resulted in a shortened version of the DISC1 gene and led to a limited functional protein. Today, DISC1 is an accepted risk gene for several psychiatric diseases like schizophrenia or depression. To understand the pathogenesis of these diseases and to discover new therapeutic approaches numerous studies focused on the function of DISC1 in the brain. As a scaffold protein that mediates the formation of protein complexes in the cell it is involved in various developmental processes, such as proliferation, migration, and differentiation of neuronal cells. The present study provides new insights into the role of DISC1 during tangential migration of GABAergic cortical interneurons. These inhibitory cells are born in the basal telencephalon and migrate into the developing cortex. Although they only account for approximately 20% of the neuronal cells in the cortex, they are composed of a variety of physiologically, morphologically, and genetically diverse cells that are crucial for the correct functionality of the brain. It has been shown that migrating interneurons express DISC1 and the loss of DISC1 leads to migration defects during tangential migration in vitro and in vivo. Further experiments focused on the cytoskeleton which accomplishes cell migration. Whereas a deficit of DISC1 rarely evokes effects on the microtubule cytoskeleton, the actin reorganisation is altered. Thereby this study depicts a possible mechanism how DISC1 exerts influence on the tangential migration of cortical interneurons. These results lead to the assumption that schizophrenia could be associated with disturbances in the GABAergic system and indicate a developmental background within psychiatric diseases that originates from defects during embryonic development

Modelling trends in digit preference patterns

Digit preference is the habit of reporting certain end digits more often than others. If such a misreporting pattern is a concern, then measures to reduce digit preference can be taken and monitoring changes in digit preference becomes important. We propose a two-dimensional penalized composite link model to estimate the true distributions unaffected by misreporting, the digit preference pattern and a trend in the preference pattern simultaneously. A transfer pattern is superimposed on a series of smooth latent distributions and is modulated along a second dimension. Smoothness of the latent distributions is enforced by a roughness penalty. Ridge regression with an L1-penalty is used to extract the misreporting pattern, and an additional weighted least squares regression estimates the modulating trend vector. Smoothing parameters are selected by the Akaike information criterion. We present a simulation study and apply the model to data on birth weight and on self-reported weight of adults

Do you understand what I want to tell you? Early sensitivity in bilinguals' iconic gesture perception and production

Previous research has shown differences in monolingual and bilingual communication. We explored whether monolingual and bilingual pre‐schoolers (N = 80) differ in their ability to understand others' iconic gestures (gesture perception) and produce intelligible iconic gestures themselves (gesture production) and how these two abilities are related to differences in parental iconic gesture frequency. In a gesture perception task, the experimenter replaced the last word of every sentence with an iconic gesture. The child was then asked to choose one of four pictures that matched the gesture as well as the sentence. In a gesture production task, children were asked to indicate ‘with their hands’ to a deaf puppet which objects to select. Finally, parental gesture frequency was measured while parents answered three different questions. In the iconic gesture perception task, monolingual and bilingual children did not differ. In contrast, bilinguals produced more intelligible gestures than their monolingual peers. Finally, bilingual children's parents gestured more while they spoke than monolingual children's parents. We suggest that bilinguals' heightened sensitivity to their interaction partner supports their ability to produce intelligible gestures and results in a bilingual advantage in iconic gesture production

Limitations to the cultural ratchet effect in young children

Although many animal species show at least some evidence of cultural transmission, broadly defined, only humans show clear evidence of cumulative culture. In the current study, we investigated whether young children show the “ratchet effect,” an important component of cumulative culture—the ability to accumulate efficient modifications across generations. We tested 16 diffusion chains—altogether consisting of 80 children—to see how they solved an instrumental task (i.e., carrying something from one location to another). We found that when the chain was seeded with an inefficient way of solving the task, 4-year-olds were able to innovate and transmit these innovations so as to reach a more efficient solution. However, when it started out with relatively efficient solutions already (i.e., the ones that children in a control condition discovered for themselves), there were no further techniques invented and/or transmitted beyond that. Thus, young children showed the ratchet effect to a limited extent, accumulating efficient modifications but not going beyond the inventive level of the individual.PostprintPeer reviewe

Beiträge zur Chemie der Azaacene

Die vorliegende Arbeit behandelt die Synthese und Charakterisierung von neuartigen organischen Farbstoffmolekülen. Vor allem die Synthese von höheren Azaacenen gestaltet sich, aufgrund der beschränkten Zugänglichkeit und Instabilität der Ausgangsmaterialien, noch immer schwierig. Der erste Teil dieser Arbeit erläutert neue Synthesestrategien über stabile Vorstufen zu solchen Azaacenderivaten. Die hohe Elektronegativität dieser Substanzklasse ist bekannt. Da solche Materialien jedoch noch nicht als Akzeptoreinheiten in Donor-Akzeptor-Molekülen getestet wurden, werden im zweiten Abschnitt genau diese erstmaligen Untersuchungen vorgestellt. Durch die Kombination der stark elektronenarmen Tetraazaanthracene mit Diarylamin-Donoren können sehr schmale Bandlücken (energetischer Abstand zwischen höchsten besetzten und niedrigsten unbesetzten Molekülorbital) von 0,7 eV generiert werden. Die Verbindung der Azaacene mit 4-Alkoxythiazolen führt zu Farbstoffen mit NIR-Absorption und niedrigen LUMO-Energien von bis zu -4,8 eV. Im abschließenden dritten Part werden die Untersuchungen zur pH-Sensibilität von N-funktionalisierten Dihydro-Azaacenen, im Speziellen den Fluorubinen, präsentiert. Über simples Ändern des pH-Wertes und den damit einhergehenden Eigenschaftsänderungen ist es möglich, mit Hilfe eines Moleküls ein breites Eigenschaftsspektrum abzudecken. So kann von einem hoch-fluoreszenten elektronenreichen System bis zu einem starken Elektronenakzeptor gewechselt werden

Fast calculation of real fluid properties for steam turbine CFD analysis with the new IAPWS standard on the spline-based table look-Up method (SBTL)

Workshop byl částečně podpořen projektem CZ.1.07/2.3.00/20.0139. Tento projekt je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky