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  • Open Access German
    Authors: 
    Schmidt, Ines;
    Country: Germany
  • Open Access German
    Authors: 
    Klein, Konstantin;
    Country: Germany

    Our knowledge regarding the history of mankind and the way that led us from Africa to Europe shows gaps in time and space, despite intensive research. Archaeological discoveries, genetic analyzes or dating provide novel results, which, however, do not always fit into the assumed migration process and cause controversy.To estimate the settlement in regions and time periods without archaeological information or to test hypotheses, numerical human dispersal models can provide answers. The expansion of the Paleolithic hunter-gatherers is a complex and non-linear process influenced by many factors, such as environmental conditions, resource occurrences, population sizes, social components like conflict or exchange, or the presence of other species. One crucial factor for the dispersal is the climate, which determines the living conditions of humans as well as food and water resources. For the quantitative evaluation of the settlement and spread of Paleolithic hunter-gatherers, two numerical models are developed, the Human Existence Potential (HEP) and the Constrained Random Walk Model (CRWM). The HEP allows a static analysis of the habitats of a human culture under climatic and environmental conditions. By using logistic regression, archaeological and climatic data are combined in order to determine a spatial potential for settlement. The HEP is then adjusted by the environmental conditions, such as the topography, glaciers or water bodies, which influence the accessibility of the resources. In addition to the spread, the HEP is used to determine contact probabilities and regionalizations, and the influence of climate changes. The CRWM is a dynamic model that simulates the dispersal of populations through the individual movement of humans. The human movement is described by a stochastic differential equation, i.e. it consists of a deterministic drift and a stochastic component. The direction of the drift is determined by the HEP and other humans, whose presence has both positive effects, since they ensure survival, and negative effects, since they consume the available resources. The stochastic movement reflects the individuality and unpredictability of human behavior. In addition, births and deaths are integrated in the CRWM. The likelihood of both depends on the size of the population and the resources available. Both models are calibrated, validated, tested and then applied to case studies. In a first case study, it is shown that the Solutrean in western Europe were cut off by an environmental barrier from the Epigravettian in eastern Europe during the Last Glacial Maximum. The expansion and contact within the Solutrean took place along the coast of Iberia, with corridors opening up inland in times of favorable climate. Another case study shows that the first phase of immigration into Europe of the modern humans of the Aurignacian came to an end in northern Iberia. The environmental conditions prevented them from spreading further south. The Neanderthals, who populated the Iberian Peninsula at the time, were well adapted to the environmental conditions there and colonized large areas of Iberia. Due to the climate change caused by an Heinrich event, Neanderthal social networks collapsed. This particularly affected the north and south of Iberia. Assuming the Neanderthals lived in significantly lower population densities than modern humans, the Heinrich event presumably led to a complete extinction of the Neanderthals on the Iberian peninsula. Overall, it can be concluded that the extinction of the Neanderthals in Iberia can be attributed more likely to the effects of an Heinrich event than to the appearance of modern humans.

  • Open Access German
    Authors: 
    Simbikangwa, Modeste;
    Country: Germany

    This study compares German and Kinyarwanda (JD60), a Bantu language spoken in Rwanda and neighboring countries (Burundi, Democratic Republic of Congo, Tanzania, and Uganda). By analyzing the linguistic levels of Kinyarwanda phonology, morphology, and syntax, the study provides an insight into the structure of Kinyarwanda, discusses and compares the salient structural differences and similarities between German and standard Kinyarwanda. The study should be understood as a contribution to comparative and contrastive linguistic research, which on the one hand will serve to improve language teaching, especially Kinyarwanda teaching and on the other hand will continue comparative linguistic research. Language comparison and contrastive analysis are very effective for this purpose, so that native German-speaking learners can acquire a deeper insight into the structure of Kinyarwanda as well as a better understanding of this language.

  • Open Access German
    Authors: 
    Wirnsberger, Maximilian;
    Publisher: Julius Klinkhardt
    Country: Germany
  • Open Access German
    Authors: 
    Franzen, Lukas;
    Country: Germany

    Eine empirisch informierte Analyse normativer Argumente aus einer liberalen Perspektive im Kontext von Volkssouveränität, Demokratie und Migration.

  • Open Access German
    Authors: 
    Paraschos, Georgios Filippos;
    Country: Germany

    Jets powered by active galactic nuclei (AGN) are some of most powerful phenomena of the cosmos. Understanding the underlying physical mechanisms is necessary to enhance our knowledge of the universe. The focus of this thesis lies on the innermost region of the radio source 3C 84, harboured in the radio galaxy NGC 1275, which exhibits such energetic jets. Perhaps connected to this jet activity is a perpendicularly to the bulk jet flow oriented structure, which was recently revealed in a RadioAstron space very-long-baseline interferometry (VLBI) image. Interpreting this structure and its implications to jet physics is one of the main motivations of this thesis. It is accomplished by utilising millimetre-VLBI observations of 3C 84 at the highest resolution, with the available data covering a period of more than twenty years and at different frequencies. The thesis is organised as follows: in Sect. 1 an overview of the astrophysical background required to interpret the data is introduced. This includes brief descriptions of the radiation received by the telescopes, of black holes and AGN, as well as of astrophysical jets. AGN classification schemes and the relevant details of jet physics are also discussed. Section 2 offers a review of the technical background, including the basics of the technique of interferometry and VLBI arrays, calibrating a VLBI data set and imaging it. In Sect. 3 we utilise quasi-simultaneous observations at 15, 43, and 86 GHz and create the highest resolution spectral index images of 3C 84 to date. Our analysis reveals the existence of a spectral index gradient in the north-south direction, with values between $\alpha_{43−86} \sim 2$ upstream of the 86 GHz VLBI core and $\alpha_{43−86} \sim -2$ downstream. In this context, we discuss the spectral index distribution. We determine the location of the jet apex to be 400 − 1500 Rs (Schwarzschild radii) upstream of the 86 GHz VLBI core, by means of two-dimensional cross-correlation analysis. In that region, the magnetic field appears to be a mix between poloidal and toroidal, with a strength of 2 − 4 G. Section 4 presents an alternative approach for pinpointing the jet apex of 3C 84, by directly imaging the core region. The temporal stacking of a number of 86 GHz data sets at different epochs confirms the existence of a double component structure present in the core region, concurring the RadioAstron result. Both a conical and a parabolic jet expansion profile are then fit to the data to determine the shape of the expansion. This constrains the position of the jet apex to 200 − 3000 Rs upstream of the 86 GHz VLBI core. Our analysis also reveals a possible change of viewing angle along the jet flow (perhaps indicative of jet bending) and sets an upper limit for the viewing angle of 35 degrees for the inner jet. Section 5 showcases a comprehensive study of the evolution and jet kinematics of 3C 84 over more than twenty years. Our analysis reveals the ejection of numerous components from the core region, which seem to move at subluminal speeds, with newer components being faster. We also checked for possible differences between the velocities of the 43 and 86 GHz components individually but only found marginal evidence of faster motion at 86 GHz. The jet width appears frequency dependent, with the jet width decreasing with in- creasing frequency, which might be explained by stratification in the context of the spine-sheath jet stratification scenario. We also produced spectral in- dex maps at 43 − 86 GHz, which show that the orientation of the spectral index gradient position angle is time variable. This further indicates that the black hole is positioned off-centred from the total intensity maximum and that the jet axis is changing with time. Finally, in Sect. 6 our analysis and results are summarised and in Sect. 7 an outlook for the future is provided.

  • Open Access German
    Authors: 
    Wiesing, Michael;
    Country: Germany

    Modern virtual reality (VR) technology has the promise to enable neuroscientists and psychologists to conduct ecologically valid experiments, while maintaining precise experimental control. However, in recent studies, game engines like Unreal Engine or Unity, are used for stimulus creation and data collection. Yet game engines do not provide the underlying architecture to measure the time of stimulus events and behavioral input with the accuracy or precision required by many experiments. Furthermore, it is currently not well understood, if VR and the underlying technology engages the same cognitive processes as a comparable real-world situation. Similarly, not much is known, if experimental findings obtained in a standard monitor-based experiment, are comparable to those obtained in VR by using a head-mounted display (HMD) or if the different stimulus devices also engage different cognitive processes. The aim of my thesis was to investigate if modern HMDs affect the early processing of basic visual features differently than a standard computer monitor. In the first project (chapter 1), I developed a new behavioral paradigm, to investigate how prediction errors of basic object features are processed. In a series of four experiments, the results consistently indicated that simultaneous prediction errors for unexpected colors and orientations are processed independently on an early level of processing, before object binding comes into play. My second project (chapter 2) examined the accuracy and precision of stimulus timing and reaction time measurements, when using Unreal Engine 4 (UE4) in combination with a modern HMD system. My results demonstrate that stimulus durations can be defined and controlled with high precision and accuracy. However, reaction time measurements turned out to be highly imprecise and inaccurate, when using UE4’s standard application programming interface (API). Instead, I proposed a new software-based approach to circumvent these limitations. Timings benchmarks confirmed that the method can measure reaction times with a precision and accuracy in the millisecond range. In the third project (chapter 3), I directly compared the task performance in the paradigm developed in chapter 1 between the original experimental setup and a virtual reality simulation of this experiment. To establish two identical experimental setups, I recreated the entire physical environment in which the experiments took place within VR and blended the virtual replica over the physical lab. As a result, the virtual environment (VE) corresponded not only visually with the physical laboratory but also provided accurate sensory properties of other modalities, such as haptic or acoustic feedback. The results showed a comparable task performance in both the non-VR and the VR experiments, suggesting that modern HMDs do not affect early processing of basic visual features differently than a typical computer monitor.

  • Open Access German
    Authors: 
    Youn, Nayoung;
    Country: Germany

    The space industry is considered a manifestation of the ‘NewSpace’ trend. Traditionally, investors have viewed the commercial opportunities of space as ‘high risk, high cost, and lengthy payment periods’ with high entry barriers. Though the commercial sector of space remains risky and expensive in comparison to other infrastructure sectors, several significant changes such as gradual improvements in managerial practices and the cost have dramatically reduced entry barriers and increased private interest in space. In addition, there are already a few cases using project finance, notably PPP, in the space industry. The change has already sparked various legal issues and may face more future challenges that require harmonized space law regulation. That is why this study examined the international legal regimes of other industries in order to advocate for the development of a more stable and efficient project finance framework for the space industry. This thesis discovered that each infrastructure industry has its own unique international legal regime along with multiple successful instances. Because there were only fundamental policies unrelated to finance at the beginning of the fundraising from private and/ or new participants, each industry organized its own legal framework. Numerous successful cases have arisen as a result of having individual legal frameworks that contain each distinctive characteristic based on necessary provisions for trustworthy project financing. A new uniform legal framework for the space industry can be envisioned from comparisons to other legal regimes for project financing. When an industry has clear and comprehensive provisions and provides broad legal guidance on industry-specific hot issues, project finance can be easily achieved. Whichever of the two ideal legal frameworks is formed, it will certainly benefit all participants in the space industry for those who employ project financing schemes. The new uniform legal framework is to promote international cooperation, encourage developing countries to develop their own infrastructures, and ensure equitable access by all participants in outer space activities.

  • Publication . Part of book or chapter of book . 2022
    Open Access German
    Authors: 
    Jędrzejowski, Łukasz;
    Publisher: Universitäts- und Stadtbibliothek Köln
    Country: Germany
  • Open Access German
    Authors: 
    Weber, Jean-Philip Daniel;
    Country: Germany

    Ziel dieser Studie war die Evaluation der Zuverlässigkeit der DCE-MR-Bildgebung in Bronchialkarzinomen. In dieser vom IRB (Institutional review board) genehmigten monozentrischen Studie wurden 40 Patienten mit NSCLC mit bis zu 5 aufeinanderfolgenden DCE-MRT-Untersuchungen eingeschlossen. Alle DCE-MRT-Untersuchungen wurden mit einem 3.0T-MRT-System durchgeführt. Die Volumen-Transfer-Konstante Ktrans wurde von 3 Untersuchern unterschiedlicher Erfahrung unter Verwendung des Zwei-Kompartiment-Tofts-Modells bewertet. Die Inter- und Intrareader-Reliabilität wurde mittels wCV, ICC und deren 95%-Konfidenzintervallen berechnet. Insgesamt wurden 107 thorakale Läsionen analysiert, einschließlich vom primären Lungenkarzinom, intrapulmonalen Metastasen (n = 91) und extrapulmonalen Metastasen (n = 16). Ktrans zeigte im Gesamtdurchschnitt eine mäßige bis gute Interrater-Reliabilität (ICC 0,716-0.841; CV 30,3-38,4%). Ktrans in Lungenläsionen ≥3 cm zeigte eine gute bis ausgezeichnete Reliabilität (ICC 0,773-0,907; CV 23,0-29,4%) im Vergleich zu Lungenläsionen <3 cm mit einer mäßigen bis guten Reliabilität (ICC 0.710-0.889; CV 31.6-48.7%). Ktrans in intrapulmonalen Läsionen zeigte eine gute Reliabilität (ICC 0,761-0,873; CV 28,9-37,5%) im Vergleich zu extrapulmonalen Läsionen mit einer schlechten bis mäßigen Reliabilität (ICC 0,018-0,680; CV 28,1-51,8%). Analog zur Interrater-Reliabilität war die Intrarater-Übereinstimmung im Gesamtdurchschnitt moderat bis gut (ICC 0,607-0,795; CV 24,6-30,4%). Die Test-Retest-Reliabilität, gemessen in einem Patienten wies einen variablen ICC auf von schlecht bis exzellent reichend (ICC 0,271-0,989; wCV 8,5-10,2%) Die DCE-MRT bietet mit der Volumen-Transfer-Konstante Ktrans einen zuverlässigen quantitativen Biomarker für ein frühes Therapie-Monitoring in Lungentumoren, jedoch mit etwas erhöhten Variabilitätskoeffizienten von 48,7% über dem von der QIBA empfohlenen Höchstwert von 20%.

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