4242 research outputs found
Sort by
The role of the atmosphere on Northern Hemisphere ice sheet evolution during the late Pleistocene
Full text linkDuring the late Pleistocene, the Northern Hemisphere ice sheets waxed and waned with a periodicity of around 100 kyr. They are among the largest topographic features that can amplify, pace or drive global climate change on different time scales. Studying ice sheet-climate feedback through numerical modelling is necessary for understanding the physical mechanisms of the Earth system. As mainly land-based ice sheets, the role of the atmosphere on Northern Hemisphere ice sheet evolution during the late Pleistocene is investigated. The evolution of Northern Hemisphere ice sheets through the last glacial cycle is simulated with the glacial index method by using the climate forcing from a general circulation model, COSMOS. By comparing the simulated results to geological reconstructions, we first show that the modelled climate is capable of capturing the main features of the ice-sheet evolution. However, large deviations exist, likely due to the absence of nonlinear interactions between ice sheet and other climate components. The model uncertainties of the climate forcing are examined using the output from nine climate models from the Paleoclimate Modelling Intercomparison Project Phase III. The results show a large variability in simulated ice sheets between the different models. We find that the ice sheet extent pattern resembles summer surface air temperature pattern at the Last Glacial Maximum, confirming the dominant role of surface ablation process for high-latitude Northern Hemisphere ice sheets. This study shows the importance of the upper boundary condition for ice sheet modelling, and implies that careful constraints on climate output is essential for simulating realistic glacial Northern Hemisphere ice sheets. Evidence from proxy records indicates that millenniala scale abrupt climate shifts, called Dansgaard-Oeschger events, happened during past glacial cycles. We show that the Dansgaard-Oeschger events can regulate the mean state of the Northern Hemisphere ice sheets. Sensitivity experiments show that the simulated mean state is influenced by the amplitude of the climatic noise. The most likely cause of this phenomenon is the nonlinear response of the surface mass balance to temperature. It could also cause the retreat processes to be faster than the buildup processes within a glacial cycle. We propose that the climate variability hindered ice sheet development and prevented the Earth system from entering a full glacial state from Marine Isotope Stage 4 to Marine Isotope Stage 3 about 60,000 years ago. Antarctic ice core and deep ocean sediment core records imply that the interglacial climate during Marine Isotope Stage 13 is relatively cold, and ice sheets were likely larger. From perspective of equilibrium simulations, we modelled the MIS 13 climate with a coupled climate-ice sheet model AWI-CM-PISM under different orbital configurations at 495, 506 and 517 kyr BP. Summer insolation at 65 N at 495 kyr BP is similar to the preindustrial, but with lower greenhouse gas values. It leads to more ice sheet buildup than present-day. Boreal summer at perihelion at 506 kyr BP causes a warmer summer over Northern Hemisphere continents. This could inhibit the development of Northern Hemisphere ice sheets. Lower obliquity induces cooling over the polar regions and is favorable for the ice sheet buildup. Besides polar regions, mountains with high elevations are also favourable for ice sheet buildup. The Cordilleran Ice Sheet is likely more sensitive and has faster response to boreal summer insolation change than the other large scale Northern Hemisphere ice sheets
Benthic communities of the Weddell Sea : Past, present and future
Full text linkThe present thesis tackles different aspects of the past, present and future of high Antarctic benthic communities of the Weddell Sea. It first compares methodological approaches to sample benthos, showing the complementarity of two quantitative techniques. Then reviews knowledge on bentho-pelagic coupling on Antarctic shelves, showing that bentho-pelagic coupling differs considerably based on local characteristics. This methodological and conceptual knowledge is uses to study the benthic communities in the hard to access Filchner Region (southern Weddell Sea), describing two novel communities, and shows the influence of environmental drivers over benthic distribution. The final topic is the temporal dynamics of benthos. For this, a long-term study which considers a unique 26-year time series of benthic data from the southeastern Weddell Sea is used. Here, benthic communities appear severely affected by a decrease of productivity, and increase of scouring potential, especially after the year 2000
Scanning und Monitoring von Technologiebewegungen : Explorative Untersuchungen mittels semantischer Patentanalysen
Full text linkTechnology movements present companies with different challenges, whether it is new competitors as a result of new markets or the risk of the disappearance of existing markets. On the other hand, technology movements lead to opportunities for companies, as new business fields can develop which open up the possibility for further growth. In order to identify the challenges and opportunities associated with technology movements at an early stage, methods of strategic early detection are required. This is where this work starts and uses scanning and monitoring as a search process for the continuous observation of technology movements. The work addresses the question of how the semantic anchor point method based on unstructured patent data has to be implemented in order to be able to detect technology movements early on in different constellations
Climatic and environmental changes during Marine Isotope Stages 3, 2 and 1 in southern Patagonia : Evidences from Laguna Potrok Aike (Argentina)
Full text linkSince the year 2001 paleolimnological studies at the maar Laguna Potrok Aike (LPA) in southern Patagonia extend our knowledge about the past regional environment conditions and about the climatically important southern hemispheric westerlies (SHW). In the frame of the ICDP (International Continental Scientific Drilling Program) project PASADO (Potrok Aike Maar Lake Sediment Archive Drilling Project) the paleolimnological research at LPA intensi-fied in 2008. After positive experiences of previous projects different research disciplines were brought together in a multi-proxy approach. The data basis was established by extensive drilling on lake sediments and field work in the catchment of the lake. The focus was represented by about 100 m deep core drillings in the lake sediment. The lithological, chronological and frequency analytical examination of the 106.09 m long composite profile 5022-2CP drilled in the southern profundal of the lake was the focus of this PhD thesis. Furthermore, results of geomorphological and sedimentological field work in the realm of the lake surrounding basin as well as in the proximate catchment were analyzed. Pelagic deposits, lake internal mass movements and tephra were identified at composite profile 5022-2CP. Striking, the amount of lake internal mass movements represented more than 50 % of the composite profile. The with lower core depths reducing ratio of mass movement deposits was interpreted as decreasing relief energy, slope consolidation and a less inclined slope angle during proceeding sediment filling of the basin. Furthermore, the intensity of lake level changes might have enforced the collapse of slopes which increased the amount of mass movement deposits. Regarding structure and compounds pelagic sediments deposited during the interglacial times distinctly differentiate from sediments deposited during glacial times. Laminated silt with carbonate crystals dominated in Holocene sediments. Laminated silt with intercalations of fine sand and coarse silt dominated in sediments of the glacial period. Lake internal mass movements and tephra layers were the only hiatus in the continuous sedimentary sequence. After radiocarbon-based age-depths-modeling 5022-2CP represents the time window of the past ca. 51.200 years. Based on sedimentary, seismic and geomorphological evidences the magnitude, geomorphological response and climate links of LPA lake level oscillation were examined. Five distinct major treads between 136 and 85 m a.s.l were identified and reflect abrasion and lake level oscillations of at least the past 51.200 years. This process expanded the lake basin from originally 2.2 km to 3.8 km
Untersuchung zur Wirksamkeit von Gruppenreflexionen auf das Wissenschaftsverständnis im Schülerlabor Backstage Science
Full text linkTo have an appropriate understanding of the nature of sciences and of their processes (Nature of Science (NOS), Nature of Scientific Inquiry (NOSI)) affords citizens the opportunity to cultivate well-funded views on science. This is fundamental to enable informed participation. The development of concepts of NOS/I (CON) proceeds implicitly. Explicating the underlying connotations via reflective actions facilitates the CON development. Visitors of the BaSci outreach lab investigate scientific issues in mediated groups. For the reflection, a Reflective Reviewing Cafe (RC) is conducted. At three tables the students can reflect and interrelate the reasons of their actions. To determine the efficacy of the RC, 16 secondary level classes visit the BaSci lab. The CONs are determined with Pre-Post surveys and the RC dialogues. The results of the surveys reveal a positive effect of the RCs on several CON aspects if the lab was visited more than once. Also the RC dialogues show an increase in appropriate CON expressions. The discursivity of the RC seems to be a cause for the positive effect observed. Future research can enable the identification of additional mechanisms
Women's Political Participation in Bangladesh Parliament : a Case Study Analysis of Women's Substantive Representation
Full text linkThis dissertation examines the case of women legislators in Bangladesh parliament (Jatiya Sangsad).It seeks to develop a deeper understanding of the relationship between descriptive representation of women and their ability to represent on behalf of women (substantive representation of women). In this dissertation, a novel approach to categorizing womena s issues was used - distinguishing strategic and practical issues - to contextualise women issues in the context of Bangladesh. This dissertation first addresses the assumption that women legislators raise more strategic women issues (pertinent to womena s rights and wellbeing) whilst representing women in parliament, whereas men are more inclined to speak about practical women issues. This dissertation then focuses on the assumption that women can make difference in bringing women related policy changes even within a system where women legislators have limited influence on the process of policy making. The analysis of the case of the Domestic Violence Prevention Act 2010 reveals three lines of connection between womena s presence and the extent of their involvement in supporting women-friendly policy change (a proxy for enactment of substantive representation). The three paths are direct, indirect, and intervening influence. Direct influence occurs when a woman legislator, as an individual, is involved directly in policy-making through womena s increased access to political leadership positions, whereas indirect influence emerges over policy representation when womena s ability to contribute to the process is limited by the formal procedures. The intervening influence is based on the observation that the link between womena s presence and policy representation can be the result of different factors, i.e. shaped by their executive position, the role of external actors, and a women-friendly political atmosphere. This dissertation explored what makes some women legislators promote a greater level of advocacy for women than other women. Acknowledging variation among women legislators, this dissertation theorises the relationship between descriptive and substantive representation assuming that the presence of women in parliament does not automatically translate into substantive representation. Rather, a variety of macro and micro level factors can explain the variation in womena s ability to act for women. Based on its analysis of empirical data obtained from parliament records and interviews, this dissertation offers insights into a number of constraining and facilitating factors on the micro and macro level which can help explain some women legislatorsa ability to intervene on women issues. Such factors include the individual choice dimension, socio-democratic characteristics, relations with external actors, different pathways to parliament, formal and informal institutional rules, electoral aspects and political circumstances
Freizeit- und Themenparks im Umbruch : Berufsfeldorientierte Fallstudien zu den Herausforderungen im 21. Jahrhundert
Full text linkDie im Forschungscluster Lebensqualität der Hochschule Bremen entstandene Studie beschäftigt sich mit aktuellen Entwicklungen im Bereich Freizeit und Themenparks und diskutiert die Veränderungen des Berufsfeldes Freizeit. Aufgegriffen werden der demografische und soziale Wandel, Tendenzen der Digitalisierung und einer zunehmenden kulturellen Vielfalt sowie Aspekte der Eventisierung und der Sicherheit in Freizeitparks. Grundlage der qualitativen Studie sind Experteninterviews und Ortsbegehungen in großen Einrichtungen. Insgesamt zeigt sich, dass die Komplexität der Anlagen wächst und neue Geschäftsfelder (Medien, Events, Resort) entstehen. Dies führt zu einer Ausdifferenzierung der Berufsbilder. Hochschulabsolventen haben ihren Platz in diesem Sektor. Flexibilität und vernetztes Denken und Handeln erscheint wichtig. Zugleich steigt die Bedeutung von Spezialisten und externen Beratern
Representations of Selected Aspects of Chemistry in Secondary School Chemistry Textbooks from Different Chinese Communities
Full text linkThis thesis is composed of four studies. It focuses on representations of selected aspects of chemistry in secondary school chemistry textbooks from different Chinese Communities, namely from the Peoplea s Republic of China, Taiwan, and the Chinese minority in Malaysia. The first study looks at the representation of the intended curriculum in grade 10 chemistry textbooks, identifying similarities and differences concerning the curriculum orientation of the seven sets of textbooks (more detail in Chapter 3, Section 3.1). The first study finds different characteristics of the intended curriculum in different Chinese communities, even though the sample shares similar ethnics, language and cultural background. This outcome, in turn, inspires us to conduct another two parallel studies (Chapter 3, Section 3.2 & 3.3), such as redox reactions and practical work. Chapter 3, Section 3.2 introduces a study on the analysis of the visual representation of redox reactions in upper secondary chemistry textbooks from PR China, Taiwan and Malaysia. The study aims at displaying how chemistry textbooks deal with visual representations of redox reactions, and further exploring if the visualizations provide any indications of the intended curriculum orientation. Chapter 3, Section 3.3 is a brief look on how practical work is presented in grade 10 chemistry textbooks and corresponding experimental textbooks from PR China, Taiwan and the Chinese minority in Malaysia. Specific instruments are adapted to analyze the type of learning, intended learning outcomes, inquiry level, and studentsa involvement, to give a basic overview of features of practical work in transferring the intended curriculum. This study explores how practical work links two domains of knowledge from observables to ideas, and makes a contribution to the body of research of practical work in secondary school chemistry education through a Chinese perspective. During the conduction on the aforementioned study, new Upper Secondary School Chemistry Curriculum Standard was released in 2017 (USSCCS) in PR China. Because the official curriculum standard serves as the guideline for textbook design, the release of the new curriculum standard inspired us to explore the differences between the new Upper Secondary School Chemistry Curriculum Standard (2017 USSCCS) and the prior Upper Secondary School Chemistry Curriculum Standard (2003 USSCCS), which are both officially released by the Ministry of Education (see Chapter 3, Section 3.4). Generally, these results show that intended curricula delivered by Taiwanese textbooks take a high degree of contextualization, while textbooks from Malaysia use a rather traditional approach. Textbooks from the Peoplea s Republic of China lie somewhere between the textbooks from Taiwan and Malaysia. Chapter 3 gives more details about the general information (Section 3.1) and richer details related to redox reactions (Section 3.2) and practical work (Section 3.3) in corresponding textbooks
Partizipation im Wohnumfeld: Benachteiligungsaspekte bei der Teilhabe von sozial benachteiligten Menschen mit Migrationshintergrund an der Gestaltung ihres Wohnumfeldes aus Public Health Perspektive
Full text linkIn urban environments, health inequalities manifest spatially in the formation of socially deprived areas . Socially disadvantaged groups with migration background are exposed to multiple burdens when their social disadvantages accumulate with health-related spatial disadvantages due to the unequal distribution of contextual factors in the living environment. Simultaneously, the social inequality of participation opportunities contributes to the fact that the same groups are least able to influence these conditions. According to the Salutogenic Model by Aaron Antonovsky (1997), participation, in the sense of personal participation in socially valued decision making, is an essential life experience that determines to what extent people are able to make resistance resources and coping strategies available, which decide upon their health and wellbeing. As a result, health promotion is not solely based on improving health-related conditions from above, but on actively involving residents, especially such of deprived areas, in decision-making processes concerning the development of their living environment. The research question is therefore: How can participation in relevant decisions about healthrelated aspects in the living environment be facilitated for socially disadvantaged groups of people with migration background and thereby improve their health chances? An explorative research design using grounded theory was applied. Two areas that are part of the Soziale Stadt program in Munich were selected as case studies. In and around those areas 23 expert interviews were conducted and evaluated over a period of 18 months. The results show that participation in the program Soziale Stadt is characterized by different understandings of participation along with different participatory practices. Three forms of participation can be distinguished: formal public participation in constructional redevelopment measures, the participation of professional actors in processes of area-development via the area committee, and projects to improve the societal participation of disadvantaged groups through socially integrative projects, focused on education and unemployment. Socially disadvantaged groups with a migration background are target group for the latter. Their participation in decision- making processes concerning the development of their living environment is thus not achieved
Strain diversity and evolution in endosymbionts of Bathymodiolus mussels
Full text linkAccumulating evidence shows that closely related strains of the same bacterial species can differ strongly in their functions. However, in intimate symbioses between bacteria and animal hosts, the impact of strain-level diversity is largely unexplored. Evolutionary theory predicts that mutualistic symbioses, should be destabilized by genetic diversity among closely-related symbiont strains. Yet, to date it is unknown if this prediction holds true in environmental symbioses. In this thesis I therefore aimed to deepen our current understanding of mutualistic symbioses, and the potential role that symbiont strain diversity and evolution may play in it. To do so, I performed high-resolution genomic analyses of the endosymbionts of Bathymodiolus mussels. My findings challenge and extent current evolutionary theories and point out the value of in-depth analysis of environmental bacterial communities to deepen our understanding of evolution, microbial interaction and symbiosis