Efficient Point Clustering for Visualization

The visualization of large spatial point data sets constitutes a problem with respect to runtime and quality. A visualization of raw data often leads to occlusion and clutter and thus a loss of information. Furthermore, particularly mobile devices have problems in displaying millions of data items. Often, thinning via sampling is not the optimal choice because users want to see distributional patterns, cardinalities and outliers. In particular for visual analytics, an aggregation of this type of data is very valuable for providing an interactive user experience. This thesis defines the problem of visual point clustering that leads to proportional circle maps. It furthermore introduces a set of quality measures that assess different aspects of resulting circle representations. The Circle Merging Quadtree constitutes a novel and efficient method to produce visual point clusterings via aggregation. It is able to outperform comparable methods in terms of runtime and also by evaluating it with the aforementioned quality measures. Moreover, the introduction of a preprocessing step leads to further substantial performance improvements and a guaranteed stability of the Circle Merging Quadtree. This thesis furthermore addresses the incorporation of miscellaneous attributes into the aggregation. It discusses means to provide statistical values for numerical and textual attributes that are suitable for side-views such as plots and data tables. The incorporation of multiple data sets or data sets that contain class attributes poses another problem for aggregation and visualization. This thesis provides methods for extending the Circle Merging Quadtree to output pie chart maps or maps that contain circle packings. For the latter variant, this thesis provides results of a user study that investigates the methods and the introduced quality criteria. In the context of providing methods for interactive data visualization, this thesis finally presents the VAT System, where VAT stands for visualization, analysis and transformation. This system constitutes an exploratory geographical information system that implements principles of visual analytics for working with spatio-temporal data. This thesis details on the user interface concept for facilitating exploratory analysis and provides the results of two user studies that assess the approach

THE USE OF NICOTINIC ACETYLCHOLINE RECEPTOR ANTAGONISTS TO TARGET BREAST TUMOR-INITIATING CELLS

The high rate of relapse often seen in breast cancer patients has been suggested to be the result of a small subset of chemotherapy-resistant cancer stem cells (CSCs), believed to be responsible for initiating tumor formation. These CSCs possess the capability to self-renew and give rise to a hierarchy of cells which makes up the bulk of a tumor. Neurotransmitters have been suggested to influence CSC self-renewal and proliferation capabilities, and antagonists of neurotransmission pathways have been implicated as possible treatment methods for chemo-resistant tumors. Using nicotinic acetylcholine receptor (nAChR) antagonists in sphere-forming assays, we have identified a very promising candidate compound: MG624. We found this compound to have a high selectivity for sphere-forming cells over non-sphere-forming cells in vitro, in a dose-dependent relationship, across a panel of cell lines as well as in patient-derived xenograft cells. This was validated in two ex vivo assays, where tumor formation was significantly delayed in mice injected with MG624-treated HCC1954 cells at both the IC50 and IC90 of the compound, indicating that MG624 does indeed target functional BTICs. MG624 was also found to synergize with both taxotere and doxorubicin chemotherapies in vitro, and shrink tumors in NOD/SCID mice when combined with taxotere in vivo. MG624 in combination with taxotere was found to induce apoptosis, and prevent cells from entering into the M-phase of the cell cycle. Interestingly, MG624 was found to eliminate intratumoral fibroblasts in combination with taxotere, despite taxotere being found to recruit fibroblasts to the tumor site when used on its own. Most importantly, the combination of MG624 and taxotere was found to significantly delay tumor progression/relapse in mice, indicating that MG624 may be an excellent candidate compound to one day be combined with chemotherapy to provide durable remission to breast cancer patients.ThesisMaster of Science (MSc

On the Design and Implementation of Easy Access to External Spatiotemporal Datasets in NFDI

Across many scientific domains, the ability to process large amounts of heterogeneous spatiotemporal data from various sources is crucial for solving challenging research questions. For example, in NFDI4Biodiversity, researchers need to combine observation data with satellite images to correlate the loss of biodiversity with climate change variables. In general, large data sets are not available on the system (called consumer) where the processing is performed, but first have to be retrieved from one or multiple external systems (called providers) that offer a corresponding service. Moreover, a consumer is often unaware of the datasets the providers offer. Ideally, a provider follows FAIR principles and thus supports mechanisms to greatly simplify the data exchange. However, in practice, there are multiple providers with valuable datasets that are not as FAIR as desired or lack spatiotemporal-specific support for data exchange. Instead of improving each potential provider at the source, we propose an intermediary spatiotemporal data exchange layer (SDExL) that helps simplify data exchange so that domain experts easily gain access to valuable data with little technical know-how

Towards an EBV Analyzer based on VAT

The Essential Biodiversity Variables (EBVs) proposed by GEO BON offer great benefits for decision makers and scientists if they are made readily available. Currently, the usage of EBVs is, however, still a challenge. The required data sets are very large, heterogeneous and temporal. This makes the usage in common tools like GIS very cumbersome. We propose the VAT system, a web-based processing engine for spatio-temporal data, as an ideal tool for EBV visualization and analysis. VAT is being developed as part of GFBio, but was designed to work independently from the start. Here, users can access a rich set of environmental layers and combine them with their own, private data. So-called exploratory workflows allow users to process data in an interactive fashion while guaranteeing reproducibility of the result. In cooperation with GEO BON we are working towards using VAT as the future EBV Browser & Analyzer. In our first use case we considered the global forest change EBV that measures the yearly global loss and gain of tree cover. In particular we wanted to investigate the change over time for a given region of interest. This information is highly relevant for decision makers as well as scientists. In our application users can choose between forest loss and forest gain and then specify their region of interest. This is either done by selecting a country from a list, or by drawing a custom polygon on the map. The relevant part of the EBV data set is added to the map as a new layer. In addition, a plot visualizes the aggregated changes over time. On the technical side this requires intersecting the raster data from the EBV with the user-defined polygon. The size of the raster makes it necessary to work with overviews in order to achieve a low-latency computation. For plotting the temporal development, we make use of our interface to R which allows us exploiting its powerful plotting functionality. In our ongoing work we will implement a public EBV catalogue that allows users to search and submit EBVs. Quality indicators will assist users to decide on the suitability of the data for their given use case. The data from the EBV catalogue will be available in the VAT system for scientists. In addition, VAT also offers simplified report views that hide the complexity of the actual computations and are thus suitable for decision makers and even the general public

Strength of Light‐Alloy Components

A FEATURE of many of the light alloys now in common use is that the stress and strain curve often does not evidence any well defined region in which the elastic strain becomes plastic strain, and a linear portion of the diagram from the origin, which in the case of so many metals represents a region of proportionality, is sometimes almost non‐existent, the diagram being curved right from the origin so that it is not possible to define any region or limit of proportionality, and the proof stress; by standard definition, has accordingly a relatively low value compared with the ultimate tensile stress of the alloy concerned. (Fig. 1).</jats:p

Imams as Bridge Builders for the Integration

Der in Osnabrück lehrende Religionswissenschaftler Rauf Ceylan präsentiert in seinem 2010 erschienenen Buch Die Prediger des Islam. Imame - wer sie sind und was sie wirklich wollen Ergebnisse seiner langjährigen Feldstudien. Es ist eine der ersten umfassenden Studien, die sich mit der Funktion der Imame an türkischen Moscheen in Deutschland befasst und durch zahlreiche Interviews eine Innensicht in die Thematik der Imame und ihrer Rolle für die Integration von muslimischen Einwanderern bietet. Das populärwissenschaftlich gehaltene Buch enthält genaue Typologien der in Deutschland predigenden Imame und betont ihre Brückenfunktion zwischen Moscheegemeindemitgliedern und der deutschen Mehrheitsgesellschaft. Ceylan möchte eine Diskussion in der Gesellschaft initiieren und schreibt deshalb bewusst populärwissenschaftlich. Allerdings bieten seine Lösungsvorschläge angesichts der neuesten Entwicklungen trotz schlagkräftiger Argumente wie etwa, dass an deutschen Universitäten ausgebildete Imame für die Etablierung des Islams in Deutschland unerlässlich sind, keine neuen Handlungsanweisungen für die deutsche Islampolitik. Nichtsdestoweniger bleibt das Buch ein wichtiger Beitrag zur aktuellen Integrations- und Islamdebatte.In his book Die Prediger des Islam (Preachers of Islam: Imams&nbsp; – who they are and what they really want), Rauf Ceylan, lecturer of Religious Studies at Osnabrück University, presents the results of many years of field study. It is one of the first comprehensive look dealing with the function imams fulfil at Turkish mosques in Germany. By means of numerous interviews it offers an insight into the topic of imams and their role for the integration of Muslim immigrants. The book contains exact typologies of the imams preaching in Germany and emphasises their function as an important link between mosque community members and the German majority society. Ceylan wants to initiate a discussion in society and therefore consciously writes in the style of popular science. However, in the light of the recent developments his proposals for solutions do not offer any new guidelines for the German politics on Islam, in spite of powerful arguments, like the one that imams who were educated at German universities are essential for the establishment of Islam in Germany. Nevertheless, the book remains an important contribution to the current debate on integration and Islam