Fast Variations of Gamma-Ray Emission in Blazars

The largest group of sources identified by EGRET are Blazars. This sub-class of AGN is well known to vary in flux in all energy bands on time-scales ranging from a few minutes (in the optical and X-ray bands) up to decades (radio and optical regimes). In addition to variations of the gamma-ray flux between different viewing periods, the brightest of these sources showed a few remarkable gamma-ray flares on time-scales of about one day, confirming the extension of the ``Intraday-Variability (IDV)'' phenomenon into the GeV range. We present first results of a systematic approach to study fast variability with EGRET data. This statistical approach confirms the existence of IDV even during epochs when no strong flares are detected. This provides additional constraints on the site of the gamma-ray emission and allows cross-correlation analyses with light curves obtained at other frequencies even during periods of low flux. We also find that some stronger sources have fluxes systematically above threshold even during quiescent states. Despite the low count rates this allows explicit comparisons of flare amplitudes with other energy bands.Comment: 5 pages including figures, LaTex, uses aipproc.sty, to appear in the proceedings of the 4th Compton Symposium at Williamsburg, V

Study of the effect of matting agents on the measurability of geometrical objects

Optical metrology has witnessed remarkable advancements over the past few years and increased its applications in many different fields. This study focuses on the effects while using a form of matting to reduce reflective effects to improve the measurements. However, challenges such as surface reflections and illumination issues must be addressed to ensure errorfree measurements. Both the effectiveness of these surface treatments and the associated deviation of the values get investigated. In addition, data from three measurement devices are used to obtain the required values with state-of-the-art accuracy. The experimental analysis of the effectiveness of the different matting methods takes at least 13 distinct methods and products into account

Characterizing mitochondrial function and structure – Mitochondrial regulation of apoptosis and visualization of mitochondria - endoplasmic reticulum interactions

Mitochondria are the powerhouse of the cell generating most of the energy for cellular mechanisms in form of ATP (adenosine triphosphate). Another important role of mitochondria is the regulation of programmed cell death, apoptosis. Apoptosis, in turn, is regulated by a complex protein network, the Bcl-2 protein family. There is a fine balance within the about 25 Bcl-2 proteins between pro- and antiapoptotic proteins. If control gets lost, cells may gain resistance to apoptosis, they can divide in an uncontrolled manner resulting in tumors and diseases like cancer may develop. The second leading cause of cancer deaths in women is cervical cancer. For proving that human papillomaviruses (HPV) are the causative agents of cervical cancer, Harald zur Hausen, a scientist of the German Cancer Research Center, Heidelberg, was awarded the Nobel Prize in 2008. In this study, one aim is to find out which antiapoptotic proteins are responsible for cervical cancer cells to become resistant to apoptosis. Using a specific method called BH3 profiling, Bcl-xL upregulation in cervical cancer cells is suggested to be responsible for apoptosis resistance. This data is supported by knock-down of Bcl-xL in cervical cancer cells finding them to regain apoptosis sensitivity. Furthermore, Bcl-2 proteins have been shown to control Ca2+ influx from ER (endoplasmic reticulum) into mitochondria and thus regulate apoptosis since high mitochondrial Ca2+ levels lead to the induction of apoptosis. Ca2+ transfer takes place at very tight interaction sites between mitochondria and ER called ER-mitochondria contact sites or mitochondria associated membranes (MAMs). More and more proteins are becoming evident to play a role in keeping those two organelles in close contact. However, the structural organization of those proteins is unknown. Since the distance between mitochondria and ER at their contact sites is only between 10 and 25 nm, it is impossible to resolve those structures with conventional confocal microscopy. This is why in this study the high resolution microscopy technique STED (stimulated emission depletion) is used to visualize MAMs. Thus, the second aim of this thesis is to image ER-mitochondria contact sites via STED microscopy to gain a deeper structural insight of these sites. A labeling strategy was established for the used STED microscopy setup to image ER, mitochondria and, as an example for a MAM protein of interest, Grp78. High resolution images could be obtained for mitochondria and Grp78 and the distribution of Grp78 with respect to the ER could be visualized. Using the here established MAM labeling strategy for STED microscopy and studying further MAM proteins in the future will enable the structural analysis of ER-mitochondria contact sites in more detail. In summary, this study provides insights into mitochondrial function and structure. 1) apoptosis regulation in cancer cells via the Bcl-2 protein network is studied, and 2) the interaction of mitochondria and the ER is visualized via high resolution STED microscopy to gain a deeper insight into the structural organization of the MAMs

Comprehensive Flow Cytometric Characterization of Bronchoalveolar Lavage Cells Indicates Comparable Phenotypes Between Asthmatic and Healthy Horses But Functional Lymphocyte Differences

Equine asthma (EA) is a highly relevant disease, estimated to affect up to 20% of all horses, and compares to human asthma. The pathogenesis of EA is most likely immune-mediated, yet incompletely understood. To study the immune response in the affected lower airways, mixed leukocytes were acquired through bronchoalveolar lavage (BAL) and the cell populations were analyzed on a single-cell basis by flow cytometry (FC). Samples of 38 horses grouped as respiratory healthy or affected by mild to moderate (mEA) or severe EA (sEA) according to their history, clinical signs, and BAL cytology were analyzed. Using FC, BAL cells and PBMC were comprehensively characterized by cell surface markers ex vivo. An increased percentage of DH24A+ polymorphonuclear cells, and decreased percentages of CD14+ macrophages were detected in BAL from horses with sEA compared to healthy horses or horses with mEA, while lymphocyte proportions were similar between all groups. Independently of EA, macrophages in BAL were CD14+CD16+, which contrasts the majority of CD14+CD16- classical monocytes in PBMC. Percentages of CD16-expressing BAL macrophages were reduced in BAL from horses with sEA compared to healthy horses. While PBMC lymphocytes predominantly contain CD4+ T cells, B cells and few CD8+ T cells, BAL lymphocytes comprised mainly CD8+ T cells, fewer CD4+ T cells and hardly any B cells. These lymphocyte subsets' distributions were similar between all groups. After PMA/ionomycin stimulation in vitro, lymphocyte activation (CD154 and T helper cell cytokine expression) was analyzed in BAL cells of 26 of the horses and group differences were observed (p=0.01-0.11). Compared to healthy horses' BAL, CD154+ lymphocytes from horses with mEA, and CD4+IL-17A+ lymphocytes from horses with sEA were increased in frequency. Activated CD4+ T helper cells were more frequent in asthmatics' (mEA, sEA) compared to healthy horses' PBMC lymphocytes. In summary, FC analysis of BAL cells identified increased polymorphonuclear cells frequencies in sEA as established, while macrophage percentages were mildly reduced, and lymphocyte populations remained unaffected by EA. Cytokine production differences of BAL lymphocytes from horses with sEA compared to healthy horses' cells point towards a functional difference, namely increased local type 3 responses in sEA

Regionalisierung meteorologischer Größen

In dem Teilprojekt von KliWES – Klimawandel und Wasserhaushalt wurden die wasserhaushaltsrelevanten Klimaelemente aus Stationsdaten in die Fläche übertragen. Regionalisiert wurden die Beobachtungsdaten der sachsenweit verfügbaren Klima- und Niederschlagsstationen von 1961 bis 2010 sowie die projizierten Stationsdaten des Regionalmodells WETTREG2010 von 1961 bis 2100. Die Übertragung erfolgte mit Hilfe von geostatistischen Verfahren. Im Ergebnis liegen flächendeckende meteorologische Daten für den Beobachtungszeitraum 1961 bis 2010 und für den Projektionszeitraum 1961 bis 2100 als Rasterdaten mit einer Auflösung von 1 km x 1 km vor. Die berechneten flächendeckenden Klimadaten bilden eine belastbare Datengrundlage für die Wasserhaushaltsmodellierungen im Projekt KliWES

Learning from arts and humanities approaches for building climate resilience in the UK

Summary:•This chapter shares insights from five arts and humanities-led UK Climate Resilience Programme projects, presenting key learnings and pathways for future research and policy interventions. •We highlight the significant potential of place-based arts and humanities approaches for working with and engaging communities in building climate resilience and driving climate action.•We underline the importance of generating genuine two-way dialogue, knowledge exchange and co-creation between academics, practitioners, and community members. •We point to the importance of robustly and reflexively assessing the effectiveness of arts and humanities-led engagement.•We argue that working collectively to develop more integrated climate and arts/cultural policy is imperative in supporting future long-term climate resilience

Kommunikation in Krisen

Das Projekt "Kommunikation in Krisen" analysiert kommunikative Prozesse in Krisen. Diese werden verstanden als eine ereignisbezogene gesellschaftliche Verunsicherung, in deren Folge sich ein temporärer, dynamischer sozialer Zusammenhang zur Bewältigung dieser Verunsicherung herausbildet. Auf der Basis von systematischen Literaturrecherchen und Gesprächen mit ausgewählten Expert*innen aus verschiedenen Akteursbereichen werden kommunikative Prozesse in der aktuell herrschenden COVID-19-Krise aufgezeigt. Um Kommunikation in Krisen systematisch zu beschreiben, wird ein figurationstheoretischer Ansatz verfolgt, der Kommunikation in Krisen als ein Interdependenzgeflecht versteht und die an der Kommunikation beteiligten Akteure, deren jeweiligen handlungsleitenden Orientierungen und kommunikativen Praktiken in den Blick nimmt. Im Zentrum stehen die bereichsspezifischen Handlungslogiken von Akteuren aus den Bereichen: Öffentliche Gesundheit und Sicherheit, Wissenschaft und Forschung, Öffentlichkeit und Journalismus, gruppenspezifische Interessen, Lebenswelt der einzelnen Mitglieder der Gesellschaft. Auf der Basis vorliegender Befunde aus der Forschung und ergänzender Expert*innengespräche werden die Wahrnehmung der Kommunikation in der Krise sowie die verschiedenen handlungsleitenden Orientierungen untersucht. Geleitet vom figurationstheoretischen Ansatz werden erstens der prozesshafte Charakter von Krisen und ihrer kommunikativen Bewältigung herausgearbeitet, zweitens die Vielfalt der an der kommunikativen Aushandlung ihrer Bewältigung beteiligten Akteure sowie drittens die Herausforderungen, die sich aus den vielfältigen rollen- und lebensweltbezogenen Ansprüchen, Erwartungen und Handlungsorientierungen ergeben. Auf dieser Grundlage werden verschiedene bereichsübergreifende Herausforderungen für die Kommunikation in Krisen identifiziert. Diese werden in Form von Spannungsfeldern beschrieben, in denen die Kommunikation in Krise verlaufen kann, etwa zwischen Konsonanz und Vielstimmigkeit, Warnung und Beruhigung, Vereinfachung und Differenzierung, Umfassende Information und Orientierungshilfe, Eigenverantwortung und Regulierung

Learning from organisational embedding for climate resilience

The term ‘resilience’, which is integral to the UK Climate Resilience Programme (UKCR), has been used increasingly in academic, practice and public discourse around climate change, and crises more generally. The term’s appeal comes from its ability to frame crises not as uncontrollable and uncertain phenomena to be feared, but as challenges over which one can triumph, with the potential for improving society

Wirkungsanalyse bestehender Klimaschutzmaßnahmen und -programme sowie Identifizierung möglicher weiterer Maßnahmen eines Energie- und Klimaschutzprogramms der Bundesregierung

Eine Analyse der deutschen Energie- und Klimapolitik hat ergeben: Nur im Maßnahmenfeld "Ausbau der Erneuerbaren Energien im Strombereich" wird voraussichtlich das Ziel ereicht. Dagegen wird in allen anderen Maßnahmenfeldern das Ziel verfehlt oder es bestehen Wirkungsdefizite der eingesetzten Politikinstrumente. Das betrifft insbesondere die Energieeffizienz auf der Nachfrageseite, aber auch die Kraft-Wärme-Kopplung und Erneuerbare Energien-Wärme. Für die Maßnahmenfelder "Fluorierte Treibhausgase", "Industrieprozesse" und "Landwirtschaft" müssen überhaupt erst verbindliche Reduktionsziele festgelegt und Politikinstrumente eingeführt werden