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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Instructions matter: a comparison of baseline conditions for cognitive emotion regulation paradigms

Diers, Kersten, Weber, Fanny, Brocke, Burkhard, Strobel, Alexander, Schönfeld, Sabine 15 July 2014 (has links) (PDF)
The choice of a meaningful baseline condition is a crucial issue for each experimental design. In the case of cognitive emotion regulation, it is common to either let participants passively view emotional stimuli without any further specific instructions or to instruct them to actively attend to and permit any arising emotions, and to contrast one of these baseline conditions with a regulation condition. While the “view” strategy can be assumed to allow for a more spontaneous emotional response, the “permit” strategy may result in a more pronounced affective and cognitive response. As these conceptual differences may be associated with differences both in subjective emotional experience and neural activation, we compared these two common control conditions within a single functional magnetic resonance imaging (fMRI) experiment, during which participants were instructed to either passively view a set of unpleasant and neutral pictures or to actively permit any emotions arising in response to the unpleasant pictures. Trial-by-trial ratings confirmed that participants perceived the unpleasant pictures as more arousing than the neutral pictures, but also indicated higher subjective arousal during the “permit negative” as compared to the “view negative” and “view neutral” conditions. While both the “permit negative” and “view negative” conditions led to increased activation of the bilateral amygdala when contrasted with the passive viewing of neutral pictures, activation in the left amygdala was increased in response to the “permit” instruction as compared to the “view” instruction for unpleasant pictures. The increase in amygdala activation in both the “permit” and “view” conditions renders both strategies as suitable baseline conditions for studies of cognitive emotion regulation. Conceptual and activation differences, however, indicate that these two variants are not exchangeable and should be chosen depending on the experimental context.
72

Readily available phosphorous and nitrogen counteract for arsenic uptake and distribution in wheat (Triticum aestivum L.)

Brackhage, Carsten, Huang, Jen-How, Schaller, Jörg, Elzinga, Evert J., Dudel, E. Gert 21 July 2014 (has links) (PDF)
Elevated arsenic content in food crops pose a serious human health risk. Apart from rice wheat being another main food crop is possibly cultivated on contaminated sites. But for wheat uptake mechanisms are not entirely understood especially with regard to nutrient fertilization and different moisture regimes taking into account heavy rainfall events due to climate change. Here we show that especially higher P-fertilization under changing redox conditions may enhance arsenic uptake. This counteracts with higher N-fertilization reducing arsenic transfer and translocation into aboveground plant parts for both higher P-fertilization and reducing soil conditions. Arsenic speciation did not change in grain but for leaves P-fertilization together with reducing conditions increased the As(V) content compared to other arsenic species. Our results indicate important dependencies of nutrient fertilization, moisture conditions and substrate type on As accumulation of wheat as one of the most important crop plants worldwide with implications for agricultural practices.
73

Built-in voltage of organic bulk heterojuction p-i-n solar cells measured by electroabsorption spectroscopy

Siebert-Henze, Ellen, Lyssenko, Vadim G., Fischer, Janine, Tietze, Max, Brueckner, Robert, Schwarze, Martin, Vandewal, Koen, Ray, Debes, Riede, Moritz, Leo, Karl 17 July 2014 (has links) (PDF)
We investigate the influence of the built-in voltage on the performance of organic bulk heterojuction solar cells that are based on a p-i-n structure. Electrical doping in the hole and the electron transport layer allows to tune their work function and hence to adjust the built-in voltage: Changing the doping concentration from 0.5 to 32 wt% induces a shift of the work function towards the transport levels and increases the built-in voltage. To determine the built-in voltage, we use electroabsorption spectroscopy which is based on an evaluation of the spectra caused by a change in absorption due to an electric field (Stark effect). For a model system with a bulk heterojunction of BF-DPB and C60, we show that higher doping concentrations in both the electron and the hole transport layer increase the built-in voltage, leading to an enhanced short circuit current and solar cell performance.
74

Gaining information about home visits in primary care: methodological issues from a feasibility study

Voigt, Karen, Taché, Stephanie, Klement, Andreas, Fankhaenel, Thomas, Bojanowski, Stefan, Bergmann, Antje 21 July 2014 (has links) (PDF)
Background: Home visits are part of general practice work in Germany. Within the context of an expanding elderly population and a decreasing number of general practitioner (GPs), open questions regarding the organisation and adequacy of GPs’ care in immobile patients remain. To answer these questions, we will conduct a representative primary data collection concerning contents and organisation of GPs’ home visits in 2014. Because this study will require considerable efforts for documentation and thus substantial involvement by participating GPs, we conducted a pilot study to see whether such a study design was feasible. Methods: We used a mixed methods design with two study arms in a sample of teaching GPs of the University Halle. The quantitative arm evaluates participating GPs and documentation of home visits. The qualitative arm focuses on reasons for non-participation for GPs who declined to take part in the pilot study. Results: Our study confirms previously observed reasons for non-response of GPs in the particular setting of home visits including lack of time and/or interest. In contrast to previous findings, monetary incentives were not crucial for GPs participation. Several factors influenced the documentation rate of home visits and resulted in a discrepancy between the numbers of home visits documented versus those actually conducted. The most frequently reported problem was related to obtaining patient consent, especially when patients were unable to provide informed consent due to cognitive deficits. Conclusions: The results of our feasibility study provide evidence for improvement of the study design and study instruments to effectively conduct a documentation-intensive study of GPs doing home visits. Improvement of instructions and questionnaire regarding time variables and assessment of the need for home visits will be carried out to increase the reliability of future data. One particularly important methodological issue yet to be resolved is how to increase the representativeness of home visit care by including the homebound patient population that is unable to provide informed consent.
75

Wirtschaftswissenschaften in Dresden

Olbrich, Michael 06 May 2011 (has links) (PDF)
Die Fakultät Wirtschaftswissenschaften der Technischen Universität reicht mit ihren Vorläufereinrichtungen bis in die Gründungsphase der Technischen Bildungsanstalt und späteren Technischen Universität Dresden im Jahr 1828. In ihrer Geschichte spiegelt sich wie kaum bei einer anderen Fakultät dieser Universität die deutsche Geschichte der vergangenen knapp 200 Jahre mit allen ihren Höhen und Tiefen, Brüchen und Neuanläufen wider. (... aus dem Vorwort)
76

Formalizing biomedical concepts from textual definitions

Tsatsaronis, George, Ma, Yue, Petrova, Alina, Kissa, Maria, Distel, Felix, Baader , Franz, Schroeder, Michael 04 January 2016 (has links) (PDF)
Background Ontologies play a major role in life sciences, enabling a number of applications, from new data integration to knowledge verification. SNOMED CT is a large medical ontology that is formally defined so that it ensures global consistency and support of complex reasoning tasks. Most biomedical ontologies and taxonomies on the other hand define concepts only textually, without the use of logic. Here, we investigate how to automatically generate formal concept definitions from textual ones. We develop a method that uses machine learning in combination with several types of lexical and semantic features and outputs formal definitions that follow the structure of SNOMED CT concept definitions. Results We evaluate our method on three benchmarks and test both the underlying relation extraction component as well as the overall quality of output concept definitions. In addition, we provide an analysis on the following aspects: (1) How do definitions mined from the Web and literature differ from the ones mined from manually created definitions, e.g., MeSH? (2) How do different feature representations, e.g., the restrictions of relations’ domain and range, impact on the generated definition quality?, (3) How do different machine learning algorithms compare to each other for the task of formal definition generation?, and, (4) What is the influence of the learning data size to the task? We discuss all of these settings in detail and show that the suggested approach can achieve success rates of over 90%. In addition, the results show that the choice of corpora, lexical features, learning algorithm and data size do not impact the performance as strongly as semantic types do. Semantic types limit the domain and range of a predicted relation, and as long as relations’ domain and range pairs do not overlap, this information is most valuable in formalizing textual definitions. Conclusions The analysis presented in this manuscript implies that automated methods can provide a valuable contribution to the formalization of biomedical knowledge, thus paving the way for future applications that go beyond retrieval and into complex reasoning. The method is implemented and accessible to the public from: https://github.com/alifahsyamsiyah/learningDL.
77

Thunderbolt in biogeochemistry: galvanic effects of lightning as another source for metal remobilization

Schaller, Jörg, Weiske, Arndt, Berger, Frank 06 February 2014 (has links) (PDF)
Iron and manganese are relevant constituents of the earth's crust and both show increasing mobility when reduced by free electrons. This reduction is known to be controlled by microbial dissimilation processes. Alternative sources of free electrons in nature are cloud-to-ground lightning events with thermal and galvanic effects. Where thermal effects of lightning events are well described, less is known about the impact of galvanic lightning effects on metal mobilization. Here we show that a significant mobilization of manganese occurs due to galvanic effects of both positive and negative lightning, where iron seems to be unaffected with manganese being abundant in oxic forms in soils/sediments. A mean of 0.025 mmol manganese (negative lightning) or 0.08 mmol manganese (positive lightning) mobilization may occur. We suggest that lightning possibly influences biogeochemical cycles of redox sensitive elements in continental parts of the tropics/subtropics on a regional/local scale.
78

Current Aspects in the Pathophysiology and Treatment of Chronic Wounds in Diabetes Mellitus

Tsourdi, Elena, Barthel, Andreas, Rietzsch, Hannes, Reichel, Andreas, Bornstein, Stefan R. 28 November 2013 (has links)
Impaired wound healing is a frequent and very severe problem in patients with diabetes mellitus, yet little is known about the underlying pathomechanisms. In this paper we review the biology of wound healing with particular attention to the pathophysiology of chronic wounds in diabetic patients. The standard treatment of diabetic ulcers includes measures to optimize glycemic control as well as extensive debridement, infection elimination by antibiotic therapy based on wound pathogen cultures, the use of moisture dressings, and offloading high pressure from the wound bed. In this paper we discuss novel adjuvant therapies with particular reference to the use of autologous skin transplants for the treatment of diabetic foot ulcers which do not respond to standard care.
79

Early Events in Foamy Virus - Host Interaction and Intracellular Trafficking

Berka, Ursula, Hamann, Martin Volker, Lindemann, Dirk 28 November 2013 (has links)
Here we review viral and cellular requirements for entry and intracellular trafficking of foamy viruses (FVs) resulting in integration of viral sequences into the host cell genome. The virus encoded glycoprotein harbors all essential viral determinants, which are involved in absorption to the host membrane and triggering the uptake of virus particles. However, only recently light was shed on some details of FV’s interaction with its host cell receptor(s). Latest studies indicate glycosaminoglycans of cellular proteoglycans, particularly heparan sulfate, to be of utmost importance. In a species-specific manner FVs encounter endogenous machineries of the target cell, which are in some cases exploited for fusion and further egress into the cytosol. Mostly triggered by pH-dependent endocytosis, viral and cellular membranes fuse and release naked FV capsids into the cytoplasm. Intact FV capsids are then shuttled along microtubules and are found to accumulate nearby the centrosome where they can remain in a latent state for extended time periods. Depending on the host cell cycle status, FV capsids finally disassemble and, by still poorly characterized mechanisms, the preintegration complex gets access to the host cell chromatin. Host cell mitosis finally allows for viral genome integration, ultimately starting a new round of viral replication.
80

Representation of water abstraction from a karst conduit with numerical discrete-continuum models

Reimann, Thomas, Giese, Markus, Geyer, Tobias, Liedl, Rudolf, Maréchal, Jean-Christophe, Shoemaker, W. Barcley 28 November 2013 (has links)
Karst aquifers are characterized by highly conductive conduit flow paths embedded in a less conductive fissured and fractured matrix resulting in strong permeability contrasts with structured heterogeneity and anisotropy. Groundwater storage occurs predominantly in the fissured matrix. Hence, most karst models assume quasi steady-state flow in conduits neglecting conduit associated drainable storage (CADS). The concept of CADS considers storage volumes, where karst water is not part of the active flow system but rather hydraulically connected to conduits (for example karstic voids and large fractures). The disregard of conduit storage can be inappropriate when direct water abstraction from karst conduits occurs, e.g. large scale pumping. In such cases, CADS may be relevant. Furthermore, the typical fixed head boundary condition at the karst outlet can be inadequate for water abstraction scenarios because unhampered water inflow is possible. The objective of this paper is to analyze the significance of CADS and flow-limited boundary conditions on the hydraulic behavior of karst aquifers in water abstraction scenarios. To this end, the numerical hybrid model MODFLOW-2005 Conduit Flow Process Mode 1 (CFPM1) is enhanced to account for CADS. Additionally, a fixed-head limited-flow (FHLQ) boundary condition is added that limits inflow from constant head boundaries to a user-defined threshold. The affect and proper functioning of these modifications is demonstrated by simplified model studies. Both enhancements, CAD storage and the FHLQ boundary, are shown to be useful for water abstraction scenarios within karst aquifers. An idealized representation of a large-scale pumping test in a karst conduit is used to demonstrate that the enhanced CFPM1 is potentially able to adequately represent water abstraction processes in both the conduits and the matrix of real karst systems.

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