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A water quality model for shallow river-lake systems and its application in river basin management
(2007)
This work documents the development and application of a new model for simulating mass transport and turnover in rivers and shallow lakes. The simulation tool called 'TRAM' is intended to complement mesoscale eco-hydrological catchment models in studies on river basin management. TRAM aims at describing the water quality of individual water bodies, using problem- and scale-adequate approaches for representing their hydrological and ecological characteristics. The need for such flexible water quality analysis and prediction tools is expected to further increase during the implementation of the European Water Framework Directive (WFD) as well as in the context of climate change research. The developed simulation tool consists of a transport and a reaction module with the latter being highly flexible with respect to the description of turnover processes in the aquatic environment. Therefore, simulation approaches of different complexity can easily be tested and model formulations can be chosen in consideration of the problem at hand, knowledge of process functioning, and data availability. Consequently, TRAM is suitable for both heavily simplified engineering applications as well as scientific ecosystem studies involving a large number of state variables, interactions, and boundary conditions. TRAM can easily be linked to catchment models off-line and it requires the use of external hydrodynamic simulation software. Parametrization of the model and visualization of simulation results are facilitated by the use of geographical information systems as well as specific pre- and post-processors. TRAM has been developed within the research project 'Management Options for the Havel River Basin' funded by the German Ministry of Education and Research. The project focused on the analysis of different options for reducing the nutrient load of surface waters. It was intended to support the implementation of the WFD in the lowland catchment of the Havel River located in North-East Germany. Within the above-mentioned study TRAM was applied with two goals in mind. In a first step, the model was used for identifying the magnitude as well as spatial and temporal patterns of nitrogen retention and sediment phosphorus release in a 100~km stretch of the highly eutrophic Lower Havel River. From the system analysis, strongly simplified conceptual approaches for modeling N-retention and P-remobilization in the studied river-lake system were obtained. In a second step, the impact of reduced external nutrient loading on the nitrogen and phosphorus concentrations of the Havel River was simulated (scenario analysis) taking into account internal retention/release. The boundary conditions for the scenario analysis such as runoff and nutrient emissions from river basins were computed by project partners using the catchment models SWIM and ArcEGMO-Urban. Based on the output of TRAM, the considered options of emission control could finally be evaluated using a site-specific assessment scale which is compatible with the requirements of the WFD. Uncertainties in the model predictions were also examined. According to simulation results, the target of the WFD -- with respect to total phosphorus concentrations in the Lower Havel River -- could be achieved in the medium-term, if the full potential for reducing point and non-point emissions was tapped. Furthermore, model results suggest that internal phosphorus loading will ease off noticeably until 2015 due to a declining pool of sedimentary mobile phosphate. Mass balance calculations revealed that the lakes of the Lower Havel River are an important nitrogen sink. This natural retention effect contributes significantly to the efforts aimed at reducing the river's nitrogen load. If a sustainable improvement of the river system's water quality is to be achieved, enhanced measures to further reduce the immissions of both phosphorus and nitrogen are required.
The Arctic plays a key role in Earth’s climate system as global warming is predicted to be most pronounced at high latitudes and because one third of the global carbon pool is stored in ecosystems of the northern latitudes. In order to improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosystems, the present study concentrates on investigations of microbial controls of methane fluxes, on the activity and structure of the involved microbial communities, and on their response to changing environmental conditions. For this purpose an integrated research strategy was applied, which connects trace gas flux measurements to soil ecological characterisation of permafrost habitats and molecular ecological analyses of microbial populations. Furthermore, methanogenic archaea isolated from Siberian permafrost have been used as potential keystone organisms for studying and assessing life under extreme living conditions. Long-term studies on methane fluxes were carried out since 1998. These studies revealed considerable seasonal and spatial variations of methane emissions for the different landscape units ranging from 0 to 362 mg m-2 d-1. For the overall balance of methane emissions from the entire delta, the first land cover classification based on Landsat images was performed and applied for an upscaling of the methane flux data sets. The regionally weighted mean daily methane emissions of the Lena Delta (10 mg m-2 d-1) are only one fifth of the values calculated for other Arctic tundra environments. The calculated annual methane emission of the Lena Delta amounts to about 0.03 Tg. The low methane emission rates obtained in this study are the result of the used remotely sensed high-resolution data basis, which provides a more realistic estimation of the real methane emissions on a regional scale. Soil temperature and near soil surface atmospheric turbulence were identified as the driving parameters of methane emissions. A flux model based on these variables explained variations of the methane budget corresponding to continuous processes of microbial methane production and oxidation, and gas diffusion through soil and plants reasonably well. The results show that the Lena Delta contributes significantly to the global methane balance because of its extensive wetland areas. The microbiological investigations showed that permafrost soils are colonized by high numbers of microorganisms. The total biomass is comparable to temperate soil ecosystems. Activities of methanogens and methanotrophs differed significantly in their rates and distribution patterns along both the vertical profiles and the different investigated soils. The methane production rates varied between 0.3 and 38.9 nmol h-1 g-1, while the methane oxidation ranged from 0.2 to 7.0 nmol h-1 g-1. Phylogenetic analyses of methanogenic communities revealed a distinct diversity of methanogens affiliated to Methanomicrobiaceae, Methanosarcinaceae and Methanosaetaceae, which partly form four specific permafrost clusters. The results demonstrate the close relationship between methane fluxes and the fundamental microbiological processes in permafrost soils. The microorganisms do not only survive in their extreme habitat but also can be metabolic active under in situ conditions. It was shown that a slight increase of the temperature can lead to a substantial increase in methanogenic activity within perennially frozen deposits. In case of degradation, this would lead to an extensive expansion of the methane deposits with their subsequent impacts on total methane budget. Further studies on the stress response of methanogenic archaea, especially Methanosarcina SMA-21, isolated from Siberian permafrost, revealed an unexpected resistance of the microorganisms against unfavourable living conditions. A better adaptation to environmental stress was observed at 4 °C compared to 28 °C. For the first time it could be demonstrated that methanogenic archaea from terrestrial permafrost even survived simulated Martian conditions. The results show that permafrost methanogens are more resistant than methanogens from non-permafrost environments under Mars-like climate conditions. Microorganisms comparable to methanogens from terrestrial permafrost can be seen as one of the most likely candidates for life on Mars due to their physiological potential and metabolic specificity.
Einleitung & Problemstellung: Beschwerden nach Beschleunigungsverletzungen der Halswirbelsäule sind oft nur unzureichend einzuordnen und diagnostizierbar. Eine eindeutige Diagnostik ist jedoch für eine entsprechende Therapie wie auch möglicherweise entstehende versicherungsrechtliche Forderungen notwendig. Die Entwicklung eines geeigneten Diagnoseverfahrens liegt damit im Interesse von Betroffenen wie auch Kostenträgern. Neben Störungen der Weichteilgewebe ist fast immer die Funktion der Halsmuskulatur in Folge eines Traumas beeinträchtigt. Dabei wird vor allem die sensorische Funktion der HWS-Muskulatur, die an der Regulation des Gleichgewichts beteiligt ist, gestört. In Folge dessen kann angenommen werden, dass es zu einer Beeinträchtigung der Gleichgewichtsregulation kommt. Die Zielstellung der Arbeit lautete deshalb, die möglicherweise gestörte Gleichgewichtsregulation nach einem Trauma im HWS-Bereich apparativ zu erfassen, um so die Verletzung eindeutig diagnostizieren zu können. Methodik: Unter Verwendung eines posturographischen Messsystems mit Kraftmomentensensorik wurden bei 478 Probanden einer Vergleichsgruppe und bei 85 Probanden eines Patientenpools Kraftmomente unter der Fußsohle als Äußerung der posturalen Balanceregulation aufgezeichnet. Die gemessenen Balancezeitreihen wurden nichtlinear analysiert, um die hohe Variabilität der Gleichgewichtsregulation optimal zu beschreiben. Über die dabei gewonnenen Parameter kann überprüft werden, ob sich spezifische Unterschiede im Schwankungsverhalten anhand der plantaren Druckverteilung zwischen HWS-Traumatisierten und den Probanden der Kontrollgruppe klassifizieren lassen. Ergebnisse: Die beste Klassifizierung konnte dabei über Parameter erzielt werden, die das Schwankungsverhalten in Phasen beschreiben, in denen die Amplitudenschwankungen relativ gering ausgeprägt waren. Die Analysen ergaben signifikante Unterschiede im Balanceverhalten zwischen der Gruppe HWS-traumatisierter Probanden und der Vergleichsgruppe. Die höchsten Trennbarkeitsraten wurden dabei durch Messungen im ruhigen beidbeinigen Stand mit geschlossenen Augen erzielt. Diskussion: Das posturale Balanceverhalten wies jedoch in allen Messpositionen eine hohe individuelle Varianz auf, so dass kein allgemeingültiges Schwankungsmuster für eine Gruppengesamtheit klassifiziert werden konnte. Eine individuelle Vorhersage der Gruppenzugehörigkeit ist damit nicht möglich. Die verwendete Messtechnik und die angewandten Auswerteverfahren tragen somit zwar zu einem Erkenntnisgewinn und zur Beschreibung des Gleichgewichtsverhaltens nach HWS-Traumatisierung bei. Sie können jedoch zum derzeitigen Stand für den Einzelfall keinen Beitrag zu einer eindeutigen Bestimmung eines Schleudertraumas leisten.
Problemstellung: Schuleingangsuntersuchungen belegen zunehmend Defizite in der motorischen und kognitiven Entwicklung von Einschülern. Im Hinblick auf Präventivmaßnahmen gilt dem motorischen und kognitiven Entwicklungsstand von Vorschulkindern ein verstärktes Forschungsinteresse. Die bisherige Wissensbasis soll mit aktuellen Untersuchungsergebnissen zum Zusammenhang von Motorik und Kognition bei Vorschulkindern erweitert werden. Methodik: Untersucht wurden 101 Kinder in vier Potsdamer Kitas im Alter von 3,5-4,6 Jahren. Zur Überprüfung der koordinativen und konditionellen Fähigkeiten wurden Standweitsprung, Sechs-Meter-Lauf, Balancieren, Einbeinstand und Seitliches Umsetzen sowie Handkoordination eingesetzt (KTK; Kiphard & Schilling 1972; Vogt 1978). Zusätzlich wurden in Anlehnung an das Brain-Gym-Konzept (Dennison 1984) körpermitteüberschreitende Armbewegungen qualitativ bewertet und auf Validität und Reliabilität geprüft. Die kognitiven Fähigkeiten wurden mit dem Bildbasierten Intelligenztest getestet (Schaarschmidt, Ricken, Kieschke & Preuß 2004). Ergebnisse: Jungen sind deutlich schneller und kräftiger als Mädchen, können aber geringfügig schlechter balancieren und feinkoordinieren. Ein Entwicklungssprung in den motorischen Leistungen ab dem vierten Lebensjahr konnte nachgewiesen werden. Weiterhin zeigte sich ein positiver signifikanter Zusammenhang zwischen der Gleichgewichtsfähigkeit und kognitiven Fähigkeiten bei den männlichen 3,5-Jährigen (r=.28-r=.32; p=0,01). Dies bestätigt: Je jünger die Kinder, desto stärker der Zusammenhang von Motorik und Intelligenz. Bei einseitiger Testung zeigten sich schwache signifikante Korrelationen von kognitiven Leistungen der Kinder und Qualifikation der Eltern (r=.18 - r=.21; p=0,01). Die Qualitative Bewertung der Arm- und Handbewegungen eignet sich wegen unbestätigter Validität und Reliabilität nicht als Untersuchungsmethode im Sinne einer frühfunktionellen Diagnostik.
Aim The aim of the present study was to examine young female volleyballers’ body build, physical abilities, technical skills and psychophysiological properties in relation to their performance at competitions. The sample consisted of 46 female volleyballers aged 13-16 years. 49 basic anthropometric measurements were measured and 65 proportions and body composition characteristics were calculated. 9 physical ability tests, 9 volleyball technical skills tests and 21 psychophysiological tests were carried out. The game performance was recorded by the computer program Game. The program enabled to fix the performance of technical elements in case of each player. The computer program Game calculated the index of proficiency in case of each girl for each element. The first control group consisted of 74 female volleyballers aged 13–15 years with whom reduced anthropometry was provided and 28 games were recorded. The second control group consisted of 586 ordinary schoolgirls aged 13–16 years with whom full anthropometry was provided. Results In order to systematize all anthropometric characteristics, we first studied the essence of the anthropometric structure of the body as a whole. It turned out to be a characteristic system where all variables are in significant correlation between one another and where the leading characteristics are height and weight. Therefore we based the classification on the mean height and weight of the whole sample. We formed a 5 class SD classification. There are three classes of concordance between height and weight: small height – small weight, medium height – medium height, big height – big weight. The other two classes were classes of disconcordance between height and weight- pycnomorphs and leptomorphs. We managed to show that gradual increase in height and weight brought about statistically significant increase in length, breadth and depth measurements, circumferences, bone thicknesses and skinfolds. There were also systematic changes in indeces and body composition characteristics. Pycnomorphs and leptomorphs also showed differences specific to their body types in body measurements and body composition. The results of all tests were submitted to basic statistical analysis and all correlations were found between all the tests (volleyball technical skills, psychophysiological abilities, physical abilities), and all basic anthropometric variables (n = 49) and all proportions and body composition characteristics (n = 65). All anthropometric measurements and test results were correlated with the index of proficiency for all elements of the game. The best linear regression models were calculated for predicting proficiency in different elements of the game. We can see that body build and all kind of tests took part in predicting the proficiency of the game. The most essential for performing attack, block and feint were anthropometric and psychophysiological models. The studied complex of body build characteristics and tests results determine the players’ proficiency at competitions, are an important tool for testing the player’s individual development, enable to choose volleyballers from among schoolgirls and represent the whole body constitutional model of a young female volleyballer. Outlook Our outlook for the future is to continue recording of all Estonian championship games with the computer program Game, to continue the players’ anthropometric measuring and psychophysiological testing at competitions and to compile a national register for assessment of development of individual players and teams.
In this work the concept of 'context' is considered in five main points. First, context is seen as always necessary for an adequate explication of the concepts of meaning and understanding. Context always plays a role and is not merely brought into consideration when handling a special class of statements or terms, or when there is doubt and clarification is necessary. Second, context cannot be completely reduced to some system of representation. The reason for this is the presence of humans, which is always an important component of a context. Humans experience situations in ways that are not always reducible to symbolic representation. Third, contexts are in principle open. In normal cases they cannot be determined or described in advance. A context is not to be equated with a set of information. Fourth, we understand the parameters of a context pragmatically, which is why we are not led into doubt or even to meaning skepticism by the open nature of a context. This pragmatic knowledge belongs to the category of an ability. Fifth, contexts are, in principle, accessible. This denies the idea that some contexts are incommensurable. There are a number of pragmatic ways of accessing unfamiliar contexts. Some of these are here examined in light of the so-called 'culture wars' in the U.S.A.