135 research outputs found
Establishing of ES cell lines for a predictable autoregulated expression of transgenes in mice
No full textDie meisten derzeit angewandten Verfahren zur Etablierung transgener Mäuse erfordern ein weitläufiges Screening von Tieren, da die zufällige Integration eines Transgens zu einer, vom Integrationsort abhängigen und daher nicht vorhersagbaren Transgen-Expression führt. Die Wiederverwendung von geeigneten Genorten in ES-Zellen zur Etablierung transgener Mäuse scheint daher sinnvoll. Zu diesem Zweck wurden autoregulierte Expressionskassetten, basierend auf dem TetOff-, TetOn-, E.REXOff- und PIPOff-System, konstruiert, die eine Identifizierung regulierbarer Genorte im Mausgenom und deren Wiederverwendung für eine vorhersagbare, regulierte Expression eines beliebigen Transgens ermöglichen sollten. Die Expressionskapazitäten der Systeme wurden in verschiedenen ES-Zelllinien analysiert. Dabei zeigte sich, dass das TetOn-System ein sehr hohes, das TetOff-System jedoch nur ein niedriges Expressionspotential besitzt. In NIH3T3- und in in vitro differenzierten Zellen wurden jedoch hohe Expressionen mit dem TetOff-System erzielt. Auf der Basis Flp-vermittelter Rekombination wurde eine Kassettenaustauschstrategie entwickelt, die eine Integration eines Transgen-exprimierenden Konstruktes in bereits charakterisierte Genorte, die mit heterospezifischen FRT-Sites markiert sind, erlauben sollte. Diese Strategie wurde in NIH3T3-Zellen getestet und führte zu Zelllinien mit homogener, vorhersagbarer Transgen-Expression.Most of the current procedures for generating transgenic mice require a large scale screening of animals, since random integration of the transgene into the mouse genome results in integration site specific and thus unpredictable transgene expression. The reuse of appropriate integration sites in mouse ES cells for creation of transgenic mice seems to overcome these problems. For this purpose, autoregulated expression cassettes, based on the TetOff, TetOn, E.REXOff and PIPOff system, were designed for screening the mouse genome for inducible chromosomal sites and subsequent reuse of these sites by Flp-mediated recombination for a predictable and regulatable expression of any gene. The expression capacities of these systems were analyzed in different ES cell lines resulting in the observation that the TetOn systems has a very high and the TetOff system only a poor expression potential. However, with the TetOff system high expressions were realized in NIH3T3 cells and in in vitro differentiated cells. For the reuse of transgenic cells a cassette exchange strategy was evolved which should allow the efficient integration of a target construct in a precharacterized locus tagged with heterospecific FRT sites. This strategy was testet in NIH3T3 cells leading to cell lines with homogenous, predictable transgene expression
Nephrocystin-1 Forms a Complex with Polycystin-1 via a Polyproline Motif/SH3 Domain Interaction and Regulates the Apoptotic Response in Mammals
No full textMutations in PKD1, the gene encoding for the receptor Polycystin-1 (PC-1), cause autosomal dominant polycystic kidney disease (ADPKD). The cytoplasmic C-terminus of PC-1 contains a coiled-coil domain that mediates an interaction with the PKD2 gene product, Polycystin-2 (PC-2). Here we identify a novel domain in the PC-1 C-terminal tail, a polyproline motif mediating an interaction with Src homology domain 3 (SH3). A screen for interactions using the PC-1 C-terminal tail identified the SH3 domain of nephrocystin-1 (NPHP1) as a potential binding partner of PC-1. NPHP1 is the product of a gene that is mutated in a different form of renal cystic disease, nephronophthisis (NPHP). We show that in vitro pull-down assays and NMR structural studies confirmed the interaction between the PC-1 polyproline motif and the NPHP1 SH3 domain. Furthermore, the two full-length proteins interact through these domains; using a recently generated model system allowing us to track endogenous PC-1, we confirm the interaction between the endogenous proteins. Finally, we show that NPHP1 trafficking to cilia does not require PC-1 and that PC-1 may require NPHP1 to regulate resistance to apoptosis, but not to regulate cell cycle progression. In line with this, we find high levels of apoptosis in renal specimens of NPHP patients. Our data uncover a link between two different ciliopathies, ADPKD and NPHP, supporting the notion that common pathogenetic defects, possibly involving de-regulated apoptosis, underlie renal cyst formation. © 2010 Wodarczyk et al
Author Correction: Cytosolic actin isoforms form networks with different rheological properties that indicate specific biological function
No full textThe Claas Relotius case: media reflections of selected national German newspapers
No full textThis bachelor thesis explores the media reflection of the case of Claas Relotius, a former reporter for Der Spiegel, who was exposed by his colleague Juan Moreno as the author of serious manipulations and fabrications in his reports. The aim of the thesis is to analyze how five major national German newspapers Die Welt, Frankfurter Allgemeine Zeitung, Die Tageszeitung, Süddeutsche Zeitung and the weekly Die Zeit reported on the affair to what extent they acknowledged their own collaboration with Relotius. The methodological basis is a qualitative content analysis of selected articles, complemented by the study of archival materials and the findings of the investigative commission that Der Spiegel established immediately after the scandal was uncovered. The results show that all the media emphasized the impact of Relotius's actions on the credibility of journalism, highlighting various themes - from personal responsibility and the responsibility of Der Spiegel itself to criticism of the literary style of reportage, as well as systemic shortcomings of the profession, the pressure to evoke emotions and the role of journalism awards. Although the editorial boards openly admitted that they had also published Relotius's articles in the past, most avoided deeper self- criticism and framed the case..
Identifying critical service issues in the service encounter – a first step in the development of a conceptual model for the shipping industry
No full textTitle Identifying critical service issues in the service encounter – a first step in the development of a conceptual for the shipping industry Author Claas Boomgaarden Key Words Service Quality, Service Encounter, SERVQUAL, INDSERV, PDSQ, LSQM, Shipping Industry, Service Science, Service Dominant Logic, Relationship Marketing Purpose The purpose of this research is to provide a first step in the development of a conceptual model for service quality in the shipping industry. Theoretical Perspectives This study is embedded in the theoretical field of service quality. Due to the lack of applicable models for the shipping industry, the existing literature of service quality for the business-to-consumer as well as business-to-business sector where combined to provide the theoretical framework for this study. Even though other models were analysed and considered in the theoretical background, eventually models like the SERVQUAL model, the INDSERV model, as well as the Physical Distribution Service Quality (PDSQ) model and the Logistics Service Quality (LSQ) model built the guideline for the data collection process. Methodology In accordance with the explorative purpose of this research, a qualitative case study, with German freight forwarders as the unit of interest, was set up. The collection of empirical data and their analysis followed the abductive hermeneutic approach. Empirical Data The empirical data for this study was derived from eight semi-structured interviews with industry experts, which lasted between twenty minutes and one hour. Conclusion The study has shown that critical service issues are depending on the value and the implied requirements of the shipped product. Nevertheless, availability, time and price as well as a flawless and fast service and good contact to contact personnel were identified as critical service issues. In order to provide a first step in the development of a conceptual model for service quality in the shipping industry, the dimensions of responsiveness, reliability/discrepancy handling, flexibility and contact to contact personnel are proposed. Further, the study shows the interconnectivity of these dimensions and proposes enabler dimensions in the form of contact person quality and process quality. By identifying these critical service issues as well as the service dimensions and their interconnectivity, the partial adaptation of established service quality measurement systems is confirmed. However, also their shortcomings are presented and this gap is closed through modification or adaptation of new dimensions
Estimation and tests for power-transformed and threshold GARCH models
No full textConsider a class of power transformed and threshold GARCH(p,q) (PTTGRACH(p,q)) model, which is a natural generalization of power-transformed and threshold GARCH(1,1) model in Hwang and Basawa (2004) and includes the standard GARCH model and many other models as special cases. We ¯rst establish the asymptotic normality for quasi-maximum likelihood estimators (QMLE) of the parameters under the condition that the error distribution has ¯nite fourth moment. For the case of heavy-tailed errors, we propose a least absolute deviations estimation (LADE) for PTTGARCH(p,q) model, and prove that the LADE is asymptotically normally distributed under very weak moment conditions. This paves the way for a statistical inference based on asymptotic normality for heavy-tailed PTTGARCH(p,q) models. As a consequence, we can construct the Wald test for GARCH structure and discuss the order selection problem in heavy-tailed cases. Numerical results show that LADE is more accurate than QMLE for heavy tailed errors. Furthermore the theory is applied to the daily returns of the Hong Kong Hang Seng Index, which suggests that asymmetry and nonlinearity could be present in the ¯nancial time series and the PTTGARCH model is capable of capturing these characteristics. As for the probabilistic structure of PTTGARCH(p,q), we give in the appendix a necessary and su±cient condition for the existence of a strictly stationary solution of the model, the existence of the moments and the tail behavior of the strictly stationary solution
The Claas Relotius case: media reflections of selected national German newspapers
No full textThis bachelor thesis explores the media reflection of the case of Claas Relotius, a former reporter for Der Spiegel, who was exposed by his colleague Juan Moreno as the author of serious manipulations and fabrications in his reports. The aim of the thesis is to analyze how five major national German newspapers Die Welt, Frankfurter Allgemeine Zeitung, Die Tageszeitung, Süddeutsche Zeitung and the weekly Die Zeit reported on the affair to what extent they acknowledged their own collaboration with Relotius. The methodological basis is a qualitative content analysis of selected articles, complemented by the study of archival materials and the findings of the investigative commission that Der Spiegel established immediately after the scandal was uncovered. The results show that all the media emphasized the impact of Relotius's actions on the credibility of journalism, highlighting various themes - from personal responsibility and the responsibility of Der Spiegel itself to criticism of the literary style of reportage, as well as systemic shortcomings of the profession, the pressure to evoke emotions and the role of journalism awards. Although the editorial boards openly admitted that they had also published Relotius's articles in the past, most avoided deeper self- criticism and framed the case...Tato bakalářská práce se zabývá mediální reflexí případu Claase Relotiuse, bývalého reportéra časopisu Der Spiegel, který byl kolegou Juanem Morenem odhalen jako autor závažných manipulací a falšování ve svých reportážích. Cílem práce je analyzovat, jakým způsobem pět významných celoněmeckých deníků Die Welt, Frankfurter Allgemeine Zeitung, Die Tageszeitung, Süddeutsche Zeitung a týdeník Die Zeit informovaly o této aféře a do jaké míry zohlednily vlastní spolupráci s Relotiusem. Metodologickým základem je kvalitativní obsahová analýza vybraných článků, doplněná o studium archivních materiálů a závěrů vyšetřovací komise, kterou Spiegel zřídil bezprostředně po odhalení skandálu. Výsledky ukazují, že všechna média zdůrazňovala dopad Relotiusova jednání na důvěryhodnost žurnalistiky, přičemž vyzdvihovala různá témata - od osobní odpovědnosti a odpovědnosti samotného magazínu, přes kritiku literárního stylu reportáže, až po systémové nedostatky profese, tlak na emoce a roli novinářských ocenění. Přestože redakce otevřeně přiznaly, že Relotiusovy texty v minulosti také publikovaly, většina se vyhýbala hlubší sebekritice a rámovala kauzu především jako selhání Spiegelu či širšího mediálního systému. Práce tak dokládá, že případ Relotius mohl být pro média příležitostí k sebekritickému zamyšlení a změně,...Katedra německých a rakouských studiíDepartment of German and Austrian StudiesFaculty of Social SciencesFakulta sociálních vě
Methodology for estimating offshore wind turbine fatigue life under combined loads of wind, waves and ice at sub-zero temperatures
No full textDue to increasing trend of building offshore wind turbines (OWTs) in seas at high latitudes where seasonal sea ice occurs, novel methods for design of such structures are needed. Specifically, the effect of ice-induced vibrations (IIVs) on fatigue life of the structures is currently poorly understood. Therefore, the goal of this paper is to analyze the current state-of-the-art approach for estimating the ice loads contribution to the fatigue life of OWTs and identify the current knowledge gaps. Moreover, the paper proposes a methodology for developing a combined load spectrum of wind, waves and ice using numerical simulations, with an ultimate goal to develop applicable Gaßner curves characterizing the variable-amplitude nature of the loading pattern. Finally, the use of small-scale fatigue tests under sub-zero temperatures in order to develop the appropriate S-N and Gaßner curves is discussed.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Offshore Engineerin
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