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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.
201

Temporal and Spatial Properties of a Yeast Multi-Cellular Amplification System Based on Signal Molecule Diffusion

Jahn, Michael, Mölle, Annett, Rödel, Gerhard, Ostermann, Kai 06 February 2014 (has links) (PDF)
We report on the spatial and temporal signaling properties of a yeast pheromone-based cell communication and amplifier system. It utilizes the Saccharomyces cerevisiae mating response pathway and relies on diffusion of the pheromone α–factor as key signaling molecule between two cell types. One cell type represents the α–factor secreting sensor part and the other the reporter part emitting fluorescence upon activation. Although multi-cellular signaling systems promise higher specificity and modularity, the complex interaction of the cells makes prediction of sensor performance difficult. To test the maximum distance and response time between sensor and reporter cells, the two cell types were spatially separated in defined compartments of agarose hydrogel (5 ´ 5 mm) and reconnected by diffusion of the yeast pheromone. Different ratios of sensor to reporter cells were tested to evaluate the minimum amount of sensor cells required for signal transduction. Even the smallest ratio, one α–factor-secreting cell to twenty reporter cells, generated a distinct fluorescence signal. When using a 1:1 ratio, the secreted pheromone induced fluorescence in a distance of up to four millimeters after six hours. We conclude from both our experimental results and a mathematical diffusion model that in our approach: (1) the maximum dimension of separated compartments should not exceed five millimeters in gradient direction; and (2) the time-limiting step is not diffusion of the signaling molecule but production of the reporter protein.
202

Intention Retrieval and Deactivation Following an Acute Psychosocial Stressor

Walser, Moritz, Fischer, Rico, Goschke, Thomas, Kirschbaum, Clemens, Plessow, Franziska 07 February 2014 (has links) (PDF)
We often form intentions but have to postpone them until the appropriate situation for retrieval and execution has come, an ability also referred to as event-based prospective memory. After intention completion, our cognitive system has to deactivate no-more-relevant intention representations from memory to avoid interference with subsequent tasks. In everyday life, we frequently rely on these abilities also in stressful situations. Surprisingly, little is known about potential stress effects on these functions. Therefore, the present study aimed to examine the reliability of event-based prospective memory and of intention deactivation in conditions of acute psychosocial stress. To this aim, eighty-two participants underwent the Trier Social Stress Test, a standardized stress protocol, or a standardized control situation. Following this treatment, participants performed a computerized event-based prospective memory task with non-salient and focal prospective memory cues in order to assess prospective memory performance and deactivation of completed intentions. Although the stress group showed elevated levels of salivary cortisol as marker of a stress-related increase in hypothalamus-pituitary-adrenal axis activity throughout the cognitive testing period compared to the no-stress group, prospective memory performance and deactivation of completed intentions did not differ between groups. Findings indicate that cognitive control processes subserving intention retrieval and deactivation after completion may be mostly preserved even under conditions of acute stress.
203

Be smart against cancer! A school-based program covering cancer-related risk behavior

Stölzel, Friederike, Seidel, Nadja, Uhmann, Stefan, Baumann, Michael, Berth, Hendrik, Hoyer, Jürgen, Ehninger, Gerhard 15 July 2014 (has links) (PDF)
Background: Several studies suggest that most school-age children are poorly informed about cancer risk factors. This study examines the effectiveness of the ‘Be smart against cancer’ (BSAC) program in promoting cancer awareness and intentions to engage in health-promoting behavior. Methods: 235 seventh-grade students were randomized to either the intervention (N = 152) or the wait-control group (N = 83). The intervention included the modules: “What is cancer?,” “Sun protection,” “Non smoking,” and “Physical activity, Healthy nutrition, and Limited alcohol consumption.” Outcomes measured at baseline and at the end of the one week BSAC program included knowledge of cancer and its behavioral risk factors, health-promoting intentions, and reported risk behavior. Results: BSAC was effective in increasing knowledge about cancer and risk factors for cancer (p < .001), as well as in increasing intentions to engage in health-promoting behavior (p < .001), independent of a student’s risk profile. Knowledge did not serve as a mediator for intention building. Conclusions: The BSAC is an effective school-based program for raising awareness of cancer, associated risk factors and intentions to engage in cancer-preventive behavior. The results indicate that the effectiveness of BSAC is independent of a student’s risk profile. Therefore, it holds considerable promise as a broadly applicable program to raise cancer awareness and promote healthy behavior intentions.
204

Striatal disorders dissociate mechanisms of enhanced and impaired response selection — Evidence from cognitive neurophysiology and computational modelling

Beste, Christian, Humphries, Mark, Saft, Carsten 15 July 2014 (has links) (PDF)
Paradoxically enhanced cognitive processes in neurological disorders provide vital clues to understanding neural function. However, what determines whether the neurological damage is impairing or enhancing is unclear. Here we use the performance of patients with two disorders of the striatum to dissociate mechanisms underlying cognitive enhancement and impairment resulting from damage to the same system. In a two-choice decision task, Huntington\'s disease patients were faster and less error prone than controls, yet a patient with the rare condition of benign hereditary chorea (BHC) was both slower and more error prone. EEG recordings confirmed significant differences in neural processing between the groups. Analysis of a computational model revealed that the common loss of connectivity between striatal neurons in BHC and Huntington\'s disease impairs response selection, but the increased sensitivity of NMDA receptors in Huntington\'s disease potentially enhances response selection. Crucially the model shows that there is a critical threshold for increased sensitivity: below that threshold, impaired response selection results. Our data and model thus predict that specific striatal malfunctions can contribute to either impaired or enhanced selection, and provide clues to solving the paradox of how Huntington\'s disease can lead to both impaired and enhanced cognitive processes.
205

MEMENTA—‘Mental healthcare provision for adults with intellectual disability and a mental disorder’. A cross-sectional epidemiological multisite study assessing prevalence of psychiatric symptomatology, needs for care and quality of healthcare provision for adults with intellectual disability in Germany: a study protocol

Koch, Andrea, Vogel, Anke, Holzmann, Marco, Pfennig, Andrea, Salize, Hans Joachim, Puschner, Bernd, Schützwohl, Matthias 21 July 2014 (has links) (PDF)
Introduction: The study ‘Mental healthcare provision for adults with intellectual disability and a mental disorder’ (MEMENTA) is a cross-sectional epidemiological study carried out in three different regions of Germany. Its main aim is to assess the prevalence of mental disorders in adults with intellectual disability (ID) as well as quality of mental healthcare for this population. Methods and analysis: The target population are persons aged between 18 and 65 years with a mild or moderate ID. The study population will be recruited through service providers. A representative sample is realised by two-stage sampling. First, institutions providing services for people with ID (sheltered workshops) are selected in a stratified cluster sampling, with strata being (1) types of service-providing non-governmental organisations and (2) sizes of their sheltered workshops. Then persons working in selected sheltered workshops are selected by simple random sampling. An estimated number of 600 adults with ID will be included. Information will be obtained from the group leaders in the sheltered workshops, informal carers or staff members in sheltered housing institutions and the person with ID. Besides the main outcome parameter of psychiatric symptomatology and problem behaviour, other outcome parameters such as needs for care, quality of life, caregiver burden, health services utilisation and costs for care are assessed using well-established standardised instruments. If a comorbid mental disorder is diagnosed, quality of mental healthcare will be assessed with open questions to all interview partners and, in addition, problem-focused interviews with a small subgroup. Analyses will be carried out using quantitative and qualitative methods. Ethics and dissemination: Approval of all three local ethics committees was obtained. Research findings will add much needed empirical information in order to improve services provided to this vulnerable group of patients.
206

Early specific cognitive-behavioural psychotherapy in subjects at high risk for bipolar disorders: study protocol for a randomised controlled trial

Pfennig, Andrea, Leopold, Karolina, Bechdolf, Andreas, Correll, Christoph U., Holtmann, Martin, Lambert, Martin, Marx, Carolin, Meyer, Thomas D., Pfeiffer, Steffi, Reif, Andreas, Rottmann-Wolf, Maren, Schmitt, Natalie M., Stamm, Thomas, Juckel, Georg, Bauer, Michael 21 July 2014 (has links) (PDF)
Background: Bipolar disorders (BD) are among the most severe mental disorders with first clinical signs and symptoms frequently appearing in adolescence and early adulthood. The long latency in clinical diagnosis (and subsequent adequate treatment) adversely affects the course of disease, effectiveness of interventions and health-related quality of life, and increases the economic burden of BD. Despite uncertainties about risk constellations and symptomatology in the early stages of potentially developing BD, many adolescents and young adults seek help, and most of them suffer substantially from symptoms already leading to impairments in psychosocial functioning in school, training, at work and in their social relationships. We aimed to identify subjects at risk of developing BD and investigate the efficacy and safety of early specific cognitive-behavioural psychotherapy (CBT) in this subpopulation. Methods/Design: EarlyCBT is a randomised controlled multi-centre clinical trial to evaluate the efficacy and safety of early specific CBT, including stress management and problem solving strategies, with elements of mindfulness-based therapy (MBT) versus unstructured group meetings for 14 weeks each and follow-up until week 78. Participants are recruited at seven university hospitals throughout Germany, which provide in- and outpatient care (including early recognition centres) for psychiatric patients. Subjects at high risk must be 15 to 30 years old and meet the combination of specified affective symptomatology, reduction of psychosocial functioning, and family history for (schizo)affective disorders. Primary efficacy endpoints are differences in psychosocial functioning and defined affective symptomatology at 14 weeks between groups. Secondary endpoints include the above mentioned endpoints at 7, 24, 52 and 78 weeks and the change within groups compared to baseline; perception of, reaction to and coping with stress; and conversion to full BD. Discussion: To our knowledge, this is the first study to evaluate early specific CBT in subjects at high risk for BD. Structured diagnostic interviews are used to map the risk status and development of disease. With our study, the level of evidence for the treatment of those young patients will be significantly raised.
207

Contribution of Small-Scale Gum and Resin Commercialization to Local Livelihood and Rural Economic Development in the Drylands of Eastern Africa

Abtew, Asmamaw Alemu, Pretzsch, Jürgen, Secco, Laura, Mohamod, Tarig Elshikh 21 July 2014 (has links) (PDF)
This paper examines the extent to which the economic gains derived from gum and resin commercialization impact rural livelihood improvement under different resource management regimes in the drylands of Ethiopia and Sudan. Primary data were collected through semi-structured interviews with 240 randomly selected small-scale producers in four regions with gradients of resource management regimes. The survey was supplemented by secondary data, group discussions and key informant interviews. In the four regions, gum and resin income contributes to 14%–23% of the small-scale producers’ household income. Absolute income was positively correlated with resource management regime and commercialization level. It was higher from cultivated resources on private lands, followed by regulated access to wild resources. In open-access resources, the producers’ income was the lowest, although accessed by the poor and women. However, dependence on gum and resin was higher in open-access resource areas. Households’ socioeconomic characteristics, resource access, production and marketing variables determining income from gum and resin were identified and their variation across the cases is discussed. Overall, gum and resin commercialization in the study areas play a potential poverty alleviation role as a source of regular income, a safety net, and a means of helping producers move out of poverty.
208

Monitoring hillslope moisture dynamics with surface ERT and hydrometric point measurement: a case study from Ore Mountains, Germany

Hübner, Rico, Heller, Katja, Günther, Thomas, Kleber, Arno 21 July 2014 (has links) (PDF)
Hillslopes are one of the basic units that mainly control water movement and flow pathways within catchments. The structure of their shallow subsurface affects water balance, e.g. infiltration, retention, and runoff. Nevertheless, there is still a gap of knowledge of the hydrological dynamics on hillslopes, notably due to the lack of generalization and transferability. To improve the knowledge of hydrological responses on hillslopes with periglacial cover beds, hydrometrical measurements have been carried out on a small spring catchment in the eastern Ore Mountains since November 2007. In addition, surface ERT measurements of several profiles were applied to enhance resolution of punctual hydrometric data. From May to December 2008 geoelectrical monitoring in nearly weekly intervals was implemented to trace seasonal moisture dynamics on the hillslope scale. To obtain the link between water content and resistivity, the parameters of Archie's law were determined using different core samples. To optimize inversion parameters and methods, the derived spatial and temporal water content distribution was compared to tensiometer data and resulting in remarkable coincidence. The measured resistivity shows a close correlation with precipitation. Depending on the amount and intensity of rain, different depths were affected by seepage water. Three different types of response to different amounts of precipitation (small, medium, high), could be differentiated. A period with a small amount causes a short interruption of the drying pattern at the surface in summer, whereas a medium amount induces a distinctive reaction at shallow depth (<0.9 m), and a high amount results in a strong response reaching down to 2 m.
209

How Well Can Saliency Models Predict Fixation Selection in Scenes Beyond Central Bias? A New Approach to Model Evaluation Using Generalized Linear Mixed Models

Nuthmann, Antje, Einhäuser, Wolfgang, Schütz, Immo 22 January 2018 (has links) (PDF)
Since the turn of the millennium, a large number of computational models of visual salience have been put forward. How best to evaluate a given model's ability to predict where human observers fixate in images of real-world scenes remains an open research question. Assessing the role of spatial biases is a challenging issue; this is particularly true when we consider the tendency for high-salience items to appear in the image center, combined with a tendency to look straight ahead (“central bias”). This problem is further exacerbated in the context of model comparisons, because some—but not all—models implicitly or explicitly incorporate a center preference to improve performance. To address this and other issues, we propose to combine a-priori parcellation of scenes with generalized linear mixed models (GLMM), building upon previous work. With this method, we can explicitly model the central bias of fixation by including a central-bias predictor in the GLMM. A second predictor captures how well the saliency model predicts human fixations, above and beyond the central bias. By-subject and by-item random effects account for individual differences and differences across scene items, respectively. Moreover, we can directly assess whether a given saliency model performs significantly better than others. In this article, we describe the data processing steps required by our analysis approach. In addition, we demonstrate the GLMM analyses by evaluating the performance of different saliency models on a new eye-tracking corpus. To facilitate the application of our method, we make the open-source Python toolbox “GridFix” available.
210

The Effect of the Accelerometer Operating Range on Biomechanical Parameters: Stride Length, Velocity, and Peak Tibial Acceleration during Running

Mitschke, Christian, Kiesewetter, Pierre, Milani, Thomas L. 22 January 2018 (has links) (PDF)
Previous studies have used accelerometers with various operating ranges (ORs) when measuring biomechanical parameters. However, it is still unclear whether ORs influence the accuracy of running parameters, and whether the different stiffnesses of footwear midsoles influence this accuracy. The purpose of the present study was to systematically investigate the influence of OR on the accuracy of stride length, running velocity, and on peak tibial acceleration. Twenty-one recreational heel strike runners ran on a 15-m indoor track at self-selected running speeds in three footwear conditions (low to high midsole stiffness). Runners were equipped with an inertial measurement unit (IMU) affixed to the heel cup of the right shoe and with a uniaxial accelerometer at the right tibia. Accelerometers (at the tibia and included in the IMU) with a high OR of ±70 g were used as the reference and the data were cut at ±32, ±16, and at ±8 g in post-processing, before calculating parameters. The results show that the OR influenced the outcomes of all investigated parameters, which were not influenced by tested footwear conditions. The lower ORs were associated with an underestimation error for all biomechanical parameters, which increased noticeably with a decreasing OR. It can be concluded that accelerometers with a minimum OR of ±32 g should be used to avoid inaccurate measurements.

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