146 research outputs found

    Multicolour STED nanoscopy with hyperspectral detection

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    Within the scope of this thesis, a new multicolour STED microscope with a hyperspectral detection was designed and built. The challenges regarding the limitation of usable fluorophores as well as the stability of the optical set-up were overcome. Different existing spectral unmixing methods were compared to a self-implemented algorithm, both in simulations and using experimental data. A detailed study of the best separation conditions for several dye combinations was carried out for each of the methods. During the experiments, a spectral blue shift of several dyes was observed and its mechanisms were investigated. The optical resolution of the set-up was dye dependent and better than 80nm for all dyes. Moreover, an excellent separation for three fluorescent bead species and good a separation for a four-colour fixed-cell sample was achieved. This was done for the first time by purely distinguishing the different emission spectra using only one wavelength for excitation and a single STED beam for depletion

    Politische und sozioökonomische Rahmenbedingungen der landwirtschaftlichen Ressourcennutzung in Sapecho, Bolivien: Forschungsbericht der Arbeitsgruppe IV zur sozioökonomischen Haushaltsbefragung

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    Ziel dieses Forschungsseminars war es, im Rahmen einer empirischen, sozialgeographischen sowie landschaftsökologischen Untersuchung in Sapecho, im Alto Beni Boliviens, die Probleme landwirtschaftlicher Ressourcennutzung in einem tropischen Entwicklungsland nachzuvollziehen. Der Schwerpunkt des Forschungsseminars lag auf der Analyse der Umstellung von konventionellen auf ökologische Landnutzungsformen, um langfristig die nachhaltige Ressourcennutzung zu verbessern und somit die lĂ€ndliche Armut zu verringern. HierfĂŒr wurden politische, sozioökonomische und geoökologische Faktoren identifiziert sowie interdisziplinĂ€r verknĂŒpft. In diesem Teilbereich der Forschung wurde der Einfluss der sozialen, politischen und ökonomischen Rahmenbedingungen auf die Landnutzungsentscheidungen der einzelnen Haushalte fokussiert. Dabei stellten Experteninterviews und teilnehmende Beobachtung unsere Untersuchungsmethoden dar

    Development of Single- and Double-sided Ladders for the ILD Vertex Detectors

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    We discuss two projects exploring the integration of thin CMOS pixel sensors in order to prototype ladders matching the geometry needed for the ILD vertex detector. The PLUME project has designed and fabricated full-size and fully functional double- sided layers which currently reach 0.6 % X0 and aim for 0.3 % X0 in mid-2012. Another approach, SERNWIETE, consists in wrapping the sensors in a polyimide-based micro-cable to obtain a supportless single-sided ladder with a material budget around 0.15 % X0. First promising samples have been produced and the full-size prototype is expected in spring 2012.Comment: International Workshop on Future Linear Colliders, LCWS 2011, Granada, Spain, 2011, 26-30 Septembe

    Recurrent stress across life may improve cognitive performance in individual rats, suggesting the induction of resilience

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    Depressive symptoms are often accompanied by cognitive impairments and recurrent depressive episodes are discussed as a potential risk for dementia. Especially, stressful life events are considered a potent risk factor for depression. Here, we induced recurrent stress-induced depressive episodes over the life span of rats, followed by cognitive assessment in the symptom-free period. Rats exposed to stress-induced depressive episodes learned faster than control rats. A high degree of stress-induced depressive-like behavior early in the paradigm was a predictor of improved cognitive performance, suggesting induction of resilience. Subsequently, exposure to lorazepam prior to stress-induced depressive episodes and cognitive testing in a nonaversive environment prevented the positive effect. This indicates a beneficial effect of the stress-associated situation, with the existence of individual coping abilities. Altogether, stress may in some have a beneficial effect, yet for those individuals unable to tackle these aversive events, consecutive unpleasant episodes may lead to worse cognitive performance later in life

    Rats overexpressing the dopamine transporter display behavioral and neurobiological abnormalities with relevance to repetitive disorders

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    The dopamine transporter (DAT) plays a pivotal role in maintaining optimal dopamine signaling. DAT-overactivity has been linked to various neuropsychiatric disorders yet so far the direct pathological consequences of it has not been fully assessed. We here generated a transgenic rat model that via pronuclear microinjection overexpresses the DAT gene. Our results demonstrate that DAT-overexpression induces multiple neurobiological effects that exceeded the expected alterations in the corticostriatal dopamine system. Furthermore, transgenic rats specifically exhibited behavioral and pharmaco-therapeutic profiles phenotypic of repetitive disorders. Together our findings suggest that the DAT rat model will constitute a valuable tool for further investigations into the pathological influence of DAT overexpression on neural systems relevant to neuropsychiatric disorders

    Defining Treatment‐Related Adverse Effects in Patients with Glioma: Distinctive Features of Pseudoprogression and Treatment‐Induced Necrosis

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    Background: Pseudoprogression (PP) and treatment‐induced brain tissue necrosis (TN) are challenging cancer treatment–related effects. Both phenomena remain insufficiently defined; differentiation from recurrent disease frequently necessitates tissue biopsy. We here characterize distinctive features of PP and TN to facilitate noninvasive diagnosis and clinical management. Materials and Methods: Patients with glioma and confirmed PP (defined as appearance 5 months after RT) were retrospectively compared using clinical, radiographic, and histopathological data. Each imaging event/lesion (region of interest [ROI]) diagnosed as PP or TN was longitudinally evaluated by serial imaging. Results: We identified 64 cases of mostly (80%) biopsy‐confirmed PP (n = 27) and TN (n = 37), comprising 137 ROIs in total. Median time of onset for PP and TN was 1 and 11 months after RT, respectively. Clinically, PP occurred more frequently during active antineoplastic treatment, necessitated more steroid‐based interventions, and was associated with glioblastoma (81 vs. 40%), fewer IDH1 mutations, and shorter median overall survival. Radiographically, TN lesions often initially manifested periventricularly (n = 22/37; 60%), were more numerous (median, 2 vs. 1 ROIs), and contained fewer malignant elements upon biopsy. By contrast, PP predominantly developed around the tumor resection cavity as a non‐nodular, ring‐like enhancing structure. Both PP and TN lesions almost exclusively developed in the main prior radiation field. Presence of either condition appeared to be associated with above‐average overall survival. Conclusion: PP and TN occur in clinically distinct patient populations and exhibit differences in spatial radiographic pattern. Increased familiarity with both conditions and their unique features will improve patient management and may avoid unnecessary surgical procedures. Implications for Practice: Pseudoprogression (PP) and treatment‐induced brain tissue necrosis (TN) are challenging treatment‐related effects mimicking tumor progression in patients with brain cancer. Affected patients frequently require surgery to guide management. PP and TN remain arbitrarily defined and insufficiently characterized. Lack of clear diagnostic criteria compromises treatment and may adversely affect outcome interpretation in clinical trials. The present findings in a cohort of patients with glioma with PP/TN suggest that both phenomena exhibit unique clinical and imaging characteristics, manifest in different patient populations, and should be classified as distinct clinical conditions. Increased familiarity with PP and TN key features may guide clinicians toward timely noninvasive diagnosis, circumvent potentially unnecessary surgical procedures, and improve response assessment in neuro‐oncology
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