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The Health Care System in Latvia
No full textThis country report provides a description of the emergence of a health care system under public responsibility in Latvia. The inception of the health care system refers to the first legislation stipulating entitlements to medical care. The report also includes a brief description of major health care reforms, and the current organization of the health care system in Latvia. This report is part of the CRC 1342 Social Policy Country Briefs Series.Deutsche Forschungsgemeinschaft (DFG)3
Segmentation-enhanced registration methods to support image-guided treatments of brain tumors
No full textThis thesis presents segmentation-enhanced registration methods to support image-guided treatments of brain tumors. The solutions are proposed for magnetic resonance imaging (MRI) and ultrasound acquisitions.
Multiparametric MRI data are acquired before and after neurosurgery. To accurately detect any pathological remnants or regrowth, a comparison of successive acquisitions is often performed, which can be further improved by the application of automatic registration methods. Such solutions are required to address the lack of one-to-one correspondence between pre- and post-operative acquisitions, which is often caused by the presence of pathology, and the need to identify the optimal MRI sequence to guide the registration process. This thesis proposes two automatic solutions for registering pre- and post-operative volumes, an iterative method and a deep learning-based approach. In both algorithms, segmentation masks can be used to select the voxels of non-corresponding pathological tissues, whose contribution is discarded from the registration process. A quantitative analysis of the impact of pathology exclusion on the registration methods is conducted. Furthermore, an evaluation of the influence of multiple MRI sequences on the registration result is presented. In addition, a deep learning method for the segmentation of resection cavities in multi-parametric MRI volumes is proposed. The influence of different MRI sequences on the segmentation of these structures is evaluated. The masks generated by the segmentation method are used in the aforementioned registration solutions.
During tumor resection procedures, multiple intraoperative ultrasound volumes are acquired at different stages to provide continuous imaging of the ongoing surgery. However, due to the brain shift, which is a displacement of brain tissue from its preoperative position, there is a need to compare successive acquisitions to track the changes during the surgery. Automatic registration methods can be employed to facilitate this task, but they have to account for the lack of correspondence between successive acquisitions. Therefore, this thesis proposes two iterative segmentation-enhanced registration methods to compensate for the brain shift in intra-patient ultrasound volumes. The first method involves automatically segmenting masks of corresponding healthy structures, which are then used to guide the registration of successive acquisitions. In the second method, masks of non-corresponding resection cavities are segmented, and subsequent ultrasound volumes are registered by excluding the contribution of the segmented structures from the search for correspondences
Causal discovery of Atlantic-Pacific interactions in observations and CMIP6 models
No full textIn a world of rapid climate change, a deeper comprehension of the Earth’s climate system is central to accurate climate projections. In this regard, understanding the dynamics governing the climate system is important. The changing climate processes are influenced by a variety of factors including both natural and anthropogenic forcings, which modulate the interactions between major modes of climate variability. These
interactions, particularly the teleconnections between the Atlantic and Pacific oceans, have a profound impact on global and regional climate patterns, necessitating a detailed exploration to grasp the complex networks of interrelated impacts. In this thesis, causal discovery approaches are applied to unravel the causal relationships for these interactions, aiming to enhance the understanding of the processes governing the climate system.
The first part of this Ph.D. thesis delves into this complex system by applying an algorithm for causal discovery to analyze observational and reanalysis datasets, in addition to large ensemble simulations from a collection of models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP). Dependent on the phases of the Pacific Decadal Variability (PDV) and the Atlantic Multidecadal Variability (AMV), different regimes with characteristic causal relationships (fingerprints) are identified in observations (and reanalyses) as well as in CMIP6. A regime-oriented causal model evaluation is then performed to assess the capability of CMIP6 models in representing observed changing interactions between PDV, AMV, and their extratropical teleconnections. Causal networks from observations show both opposite-sign and same-sign responses between AMV and PDV under specific conditions. Historical CMIP6 simulations exhibit varying skill in simulating the observed causal patterns but overall perform better when PDV and AMV are out of phase. Additionally, the two largest ensembles, (in terms of number of realizations) were found to contain realizations with most similar causal fingerprints to observations. For most regimes, these same models also showed higher network similarity when compared to each other.
In the second part of this thesis, the focus is on examining the tropical and extra-tropical routes connecting Pacific and Atlantic modes of variability on seasonal to interannual timescales. Following up on recent studies, this analysis characterizes two distinctive phases: the Pacificdriven
regime (1950-1983) and theAtlantic-driven regime (1985-2014), spotlighting the varying
role of El Niño-Southern Oscillation (ENSO) in shaping sea surface temperature variability in the tropical Atlantic. Guided by the results of the first study, the use of large ensemble simulations in this second study intends to separate the contributions of external forcings from natural internal variability. A comparative analysis examines results from observations (and reanalysis) in contrast to those from Pacific pacemaker simulations, unveiling effects of anthropogenic external forcing, especially in the most recent decades. Specifically, the 1985-2014 results suggest that human-induced anomalous tropical north Atlantic warming greatly contributed to La Niña-like cooling over the tropical Pacific through the strengthening of the Pacific Walker circulation. On the other hand, the causal analysis of the pre-industrial control run emphasizes the importance of natural internal variability on decadal timescales in modulating the interplay between interannual climate variability modes over the two basins.
Generally, the results presented in this thesis demonstrate the large potential of causal discovery for process-oriented model evaluation that can substantially enhance our understanding of climate variability and provide robust diagnostics for refining climate models. Furthermore, this thesis underscores the role of the intricate interplay between natural variability and external forcings in shaping climate patterns, and advocates for further research to precisely attribute the observed changes in the climate system. The insights gained are hence significant for formulating more accurate and informed climate projections as well as adaptation and mitigation strategies
Mitigating dark patterns through responsible design - ethical design considerations for user-centred technologies
No full textEvery digital interface is the result of intentions, incentives, and design philosophies. They can lead to user-friendly and empowering technologies or exploiting and manipulative ones that persuade users into engaging in actions they may regret later. The past decade of HCI research has explored the latter phenomenon, describing them as deceptive design strategies or "dark patterns". In this vein, studies have fostered a growing taxonomy of related instances in various domains.
These existing findings offer space for synthesised frameworks and open avenues for transdisciplinary work. Moreover, underlying mechanisms of dark patterns have yet to be studied to grasp their implications on users. Extracted knowledge can lead to the development of tools to understand dark patterns better and mitigate their effects.
Addressing these gaps and drawing from a series of qualitative and quantitative research studies, included in this cumulative thesis, its contributions are threefold: It explores dark patterns in SNS and adds domain-specific types to the related scholarship. It describes users' perception of dark patterns and spotlights difficulties in protecting themselves from nefarious SNS and CUI interfaces. Lastly, it contributes to design theory by revealing where dark patterns manifest and how responsible design can be used to mitigate them. Together, the contributions span the three angles – design, users, and guidelines – of the Responsible Design Triangle. This model reflects the interrelationships and dependencies between the angles
Entwicklung drahtloser Sensorknoten für Integration in Faser-Kunststoff-Verbundmaterialien
No full textRising importance of energy-efficient technology increasingly gives rise to usage of Fibe-Reinforced Polymers (FRP) due to the huge potentials offered for lightweight, durable structures.
In order to achieve the desired material properties and subsequent behavior, FRP production has to be carefully monitored and controlled.
This thesis presents a collection of novel approaches for monitoring FRP fabrication processes and subsequent structural health monitoring applications, by developing flexible, wireless sensors for integration into FRP.
To facilitate industrial application, the overall sensor concept explicitly focuses on simple and cost-efficient producibility, and intentionally targets automated sensor placement in an automated FRP production context.
In order to minimize impact on FRP material integrity, and ease vacuum setup and part handling, the sensors need neither wires nor battery for operation, by making use of Radio Frequency Identification (RFID) technology.
Two sensor types have been designed, individually targeting the two main applications with a different focus.
Both sensors are able to precisely measure local material temperature.
This gives insights into FRP fabrication processes, e.g.resin presence and curing temperatures, and later on into FRP operation conditions.
Additionally, the first sensor presented is able to measure bi-axial mechanical strain of the finished FRP material by using a temperature-compensated full bridge strain gauge.
The second sensor uses a structure of substrate-integrated, interdigital electrodes to give real-time insights into polymer curing behavior by measuring the changing capacitance between the electrode fingers, similar to a common dielectric sensor.
To support electrode design for usage with the sensors, a thorough investigation is conducted regarding basic properties of interdigital electrodes, that have been fabricated on flexible polyimide foil via common PCB production technology.
This thesis elaborates on development, characterization and limitations of the sensors, and it is shown how they can be used to monitor FRP production and mechanical strain of sensor-integrated specimens
Political action and news use of the Fridays for Future Movement in Germany
No full textDer Titel der Dissertation lautet „Political action and news use of the Fridays for Future Movement in Germany“ und beschäftigt sich mit der politischen Nachrichtennutzung von Fridays for Future-Unterstützer:innen unter Einsatz neuester Smartphone-Tracking-Verfahren. Dabei kombinierte Patrick Zerrer ein aufwendiges Forschungsdesign mit innovativen Methoden der Datenerhebung, die neue Möglichkeiten eröffnen, kleinteiliges Nutzungsverhalten auf dem Smartphone, wie das Lesen politischer Posts in Social Media oder die politische Konversation via WhatsApp, zu untersuchen, ohne die Privatsphäre der Teilnehmer:innen zu verletzen. Die so erhobenen Daten zeichnen ein umfassendes Bild der Informationsnutzung junger und politisch aktiver Menschen in einer digitalen und mobilen Medienumgebung
The role of sea ice in the surface freshwater flux of the southern Weddell Sea: Insights from sea ice–ice shelf–ocean model simulations
No full textThe strongest sea ice growth rates are found in coastal polynyas, where steady offshore winds promote divergent ice movement during the freezing season. The strong sea ice production on the southern Weddell Sea continental shelf leads to the densification of the near-surface waters, resulting in the formation of High Salinity Shelf Water (HSSW) that feeds the global overturning circulation and fuels the basal melt of vast Filchner-Ronne Ice Shelf (FRIS). The Finite Element Sea ice–ice shelf–Ocean Model (FESOM) forced by output from the regional atmospheric model COSMO-CLM (CCLM) with 14 km horizontal resolution is used in this thesis to investigate the role of sea ice for the surface freshwater flux of the southern Weddell Sea, with a particular focus on coastal polynyas. The presence of stationary icescape features (i.e. fast-ice areas and grounded icebergs) can influence the formation of polynyas and, therefore, impact sea ice production. The representation of the icescape in the model is included by prescribing the position, shape, and temporal evolution of a largely immobile ice mélange that was forming between FRIS and the grounded iceberg A23-A based on satellite data
Characterization of the interactions between molecular chaperones and the amyloid protein Huntingtin throughout its aggregation pathway
No full textProtein misfolding and subsequent aggregation characterize most neurodegenerative diseases and are associated with impaired protein homeostasis (proteostasis). As prominent components of the proteostasis network, molecular chaperones have been
identified as modulators of protein aggregation. Understanding their mechanisms of
action paves the way for their use as a therapeutic strategy against neurodegenerative
diseases.
Huntington's disease (HD) is an inherited neurodegenerative disease caused by the abnormal expansion of CAG repeats in the first exon of the Huntingtin protein.
Aggregation of the pathogenic HTTExon1 is suggested as the primary cause of
neuronal deterioration.
Previously, it was shown that a trimeric chaperone complex composed of Hsc70,
DNAJB1, and Apg2 can inhibit pathogenic HTTExon1 aggregation and disaggregate
preformed HTTExon1 fibrils. As a member of the J-domain protein (JDP) family, and a
co-chaperone of Hsc70, DNAJB1 is known to recognize protein substrates, to transfer
them to Hsc70, and stimulate the ATPase activity of Hsc70. Recently, a binding
interface between DNAJB1 and HTTExon1 has been identified and this work has
contributed to the analysis of the effect of this binding site in HTTExon1 suppression
and disaggregation activities by the trimeric chaperone complex. In vitro analyses
showed that this binding site and unique features of DNAJB1 conferred specificity and
functionality, distinguishing it from other JDPs.
Furthermore, association between the trimeric chaperones and HTTExon1 along its
aggregation pathway was investigated. The data revealed that DNAJB1 and Hsc70
associate with aggregating HTTExon1 only in the presence of each other and an intact
ATPase cycle, suggesting a cooperative association of these chaperones with
HTTExon1 during aggregation. This association was found to be stable to detergent,
suggesting that irreversible sequestration of chaperones in HTTExon1 aggregates is
associated with the eventual failure of the trimeric chaperone complex in suppressing
HTTExon1 aggregation
Long-term vegetation change in semi-natural grasslands – disentangling trends from pseudo-turnover
No full textGrasslands cover a significant part of the Earth’s surface and support a large proportion of its biodiversity. Despite their importance, species-rich grasslands have been severely decimated and degraded over the past century. Resurvey studies can provide the necessary knowledge of current developments in grasslands to enable effective conservative action. Many insightful resurveys have been conducted in recent decades, however, grassland ecosystems have been under-represented in these studies.
Data collected during fieldwork often contains a significant amount of noise due to inaccuracies in the data collection, inappropriate study design, and random variation in species composition. In the methodological part of this thesis, we aim to contribute to disentangling signal from noise in resurvey studies. Specific resurvey studies in Nardus grasslands and calcareous grasslands were conducted.
We introduced the concept of “baseline turnover” to measure the extent of vegetation changes that occur regularly due to stochastic fluctuations in species composition. It is an important factor to consider when attempting to distinguish signal from noise in studies of vegetation change.
With an article on the statistical phenomenon of “regression to the mean”, we aimed to raise awareness of this potential pitfall in the statistical analysis of resurveys and longitudinal experiments.
A resurvey of Nardus grasslands in western Germany confirmed the trend of soil pH increase in acidic soils. However, the widespread eutrophication of Nardus grasslands was only weakly pronounced. We believe that this is due to the exceptionally consistent management of annual mowing over the previous 30 years.
The initial survey of calcareous grasslands in Lower Saxony, Germany, confirmed that particularly warm and dry microclimates have had a positive effect on the characteristic species in the past. In the resurvey, the vegetation showed clear signs of the severe drought that had occurred. This can be interpreted as a warning that sites that previously favoured typical calcareous grassland species may develop conditions that are too extreme in the future