Spatio-temporal resolution studies on a highly compact ultrafast electron diffractometer

Time-resolved diffraction with femtosecond electron pulses has become a promising technique to directly provide insights into photo induced primary dynamics at the atomic level in molecules and solids. Ultrashort pulse duration as well as extensive spatial coherence are desired, however, space charge effects complicate the bunching of multiple electrons in a single pulse.Weexperimentally investigate the interplay between spatial and temporal aspects of resolution limits in ultrafast electron diffraction (UED) on our highly compact transmission electron diffractometer. To that end, the initial source size and charge density of electron bunches are systematically manipulated and the resulting bunch properties at the sample position are fully characterized in terms of lateral coherence, temporal width and diffracted intensity.Weobtain a so far not reported measured overall temporal resolution of 130 fs (full width at half maximum) corresponding to 60 fs (root mean square) and transversal coherence lengths up to 20 nm. Instrumental impacts on the effective signal yield in diffraction and electron pulse brightness are discussed as well. The performance of our compactUEDsetup at selected electron pulse conditions is finally demonstrated in a time-resolved study of lattice heating in multilayer graphene after optical excitation.

Spatio-temporal patterns of herbage availability and livestock movements: A cross-border analysis in the Chinese-Mongolian Altay

Due to increasing population and the recent implementation of policies to intensify the use of land and water resources, the transhumant pastoral systems in the Chinese-Mongolian Altay-Dzungarian region are rapidly changing, leading to modifications of herd size, herd composition and spatial distribution of livestock grazing. This may have major consequences for the supply and quality of rangeland biomass. Despite similar topographic settings, the socio-political framework for Chinese and Mongolian pastoralists differs significantly, leading to differences in rangeland utilization. To substantiate these claims, the long-distance transhumance routes, frequency of pasture changes, daily grazing itineraries and size of pastures were recorded by means of GPS tracking of cattle and goats on 1,535 (China) and 1,396 (Mongolia) observation days. The status quo of the main seasonal pastures was captured by measuring the herbage offer and its nutritive value in 869 sampling spots. In the Altay-Dzungarian region, small ruminant herds covered up to 412 km (Mongolia) and grazed on up to nine pastures per year (China). In Mongolia, the herds’ average duration of stay at an individual pasture was longer than in China, particularly in spring and autumn. Herbage allowance at the onset of a grazing period (kg dry matter per sheep unit and day) ranged from 34/17 to 91/95 (China/Mongolia). Comparing crude protein and phosphorous concentrations of herbage, in China, the highest concentrations were measured for spring and summer pastures, whereas in Mongolia, the highest concentrations were determined for autumn and winter pastures. Based on our data, we conclude that regulation of animal numbers and access to pastures seemingly maintained pasture productivity in China, especially at high altitudes. However, this policy may prohibit flexible adaptation to sudden environmental constraints. In contrast, high stocking densities and grazing of pastures before flowering of herbaceous plants negatively affected rangeland productivity in Mongolia, especially for spring and summer pastures.

Methodische Grundlagen zur Bewahrung und Wiederherstellung großräumig funktionsfähiger ökologischer Beziehungen in der räumlichen Umweltplanung

Mit der Verwirklichung ,Ökologischer Netzwerke‘ werden Hoffnungen zum Stopp des Verlustes der biologischen Vielfalt verknüpft. Sowohl auf gesamteuropäischer Ebene (Pan-European Ecological Network - PEEN) als auch in den einzelnen Staaten entstehen Pläne zum Aufbau von Verbundsystemen. Im föderalen Deutschland werden kleinmaßstäbliche Biotopverbundplanungen auf Landesebene aufgestellt; zum nationalen Biotopverbund bestehen erste Konzepte. Die vorliegende Arbeit ist auf diese überörtlichen, strategisch vorbereitenden Planungsebenen ausgerichtet. Ziele des Verbunds sind der Erhalt von Populationen insbesondere der gefährdeten Arten sowie die Ermöglichung von Ausbreitung und Wanderung. Aufgrund fehlender Datengrundlagen zu den Arten und Populationen ist es nicht ohne weiteres möglich, die Konzepte und Modelle der Populationsökologie in die überörtlichen Planungsebenen zu übertragen. Gemäß der o.g. Zielstellungen sollte sich aber die Planung von Verbundsystemen an den Ansprüchen der auf Verbund angewiesenen Arten orientieren. Ziel der Arbeit war die Entwicklung einer praktikablen GIS-gestützten Planungshilfe zur größtmöglichen Integration ökologischen Wissens unter der Bedingung eingeschränkter Informationsverfügbarkeit. Als Grundlagen dazu werden in Übersichtsform zunächst die globalen, europäisch-internationalen und nationalen Rahmenbedingungen und Anforderungen bezüglich des Aufbaus von Verbundsystemen zusammengestellt. Hier sind die Strategien zum PEEN hervorzuheben, die eine Integration ökologischer Inhalte insbesondere durch die Berücksichtigung räumlich-funktionaler Beziehungen fordern. Eine umfassende Analyse der landesweiten Biotopverbundplanungen der BRD zeigte die teilweise erheblichen Unterschiede zwischen den Länderplanungen auf, die es aktuell nicht ermöglichen, ein schlüssiges nationales Konzept zusammenzufügen. Nicht alle Länder haben landesweite Biotopverbundplanungen und Landeskonzepte, bei denen dem geplanten Verbund die Ansprüche von Arten zugrunde gelegt werden, gibt es nur ansatzweise. Weiterhin wurde eine zielgerichtete Eignungsprüfung bestehender GIS-basierter Modelle und Konzepte zum Verbund unter Berücksichtigung der regelmäßig in Deutschland verfügbaren Datengrundlagen durchgeführt. Da keine integrativen regelorientierten Ansätze vorhanden waren, wurde der vektorbasierte Algorithmus HABITAT-NET entwickelt. Er arbeitet mit ,Anspruchstypen‘ hinsichtlich des Habitatverbunds, die stellvertretend für unterschiedliche ökologische Gruppen von (Ziel-) Arten mit terrestrischer Ausbreitung stehen. Kombiniert wird die Fähigkeit zur Ausbreitung mit einer Grobtypisierung der Biotopbindung. Die wichtigsten Grundlagendaten bilden die jeweiligen (potenziellen) Habitate von Arten eines Anspruchstyps sowie die umgebende Landnutzung. Bei der Bildung von ,Lebensraumnetzwerken‘ (Teil I) werden gestufte ,Funktions- und Verbindungsräume‘ generiert, die zu einem räumlichen System verknüpft sind. Anschließend kann die aktuelle Zerschneidung der Netzwerke durch Verkehrstrassen aufgezeigt werden, um darauf aufbauend prioritäre Abschnitte zur Wiedervernetzung zu ermitteln (Teil II). Begleitend wird das Konzept der unzerschnittenen Funktionsräume (UFR) entworfen, mit dem die Indikation von Habitatzerschneidung auf Landschaftsebene möglich ist. Diskutiert werden schließlich die Eignung der Ergebnisse als kleinmaßstäblicher Zielrahmen, Tests zur Validierung, Vergleiche mit Verbundplanungen und verschiedene Setzungen im GIS-Algorithmus. Erläuterungen zu den Einsatzmöglichkeiten erfolgen beispielsweise für die Bereiche Biotopverbund- und Landschaftsplanung, Raumordnung, Strategische Umweltprüfung, Verkehrswegeplanung, Unterstützung des Konzeptes der Lebensraumkorridore, Kohärenz im Schutzgebietssystem NATURA 2000 und Aufbau von Umweltinformationssystemen. Schließlich wird ein Rück- und Ausblick mit der Formulierung des weiteren Forschungsbedarfs verknüpft.

Influence of the buffer environment on the Relative Biological Effectiveness of carbon ion radiation, investigated by Scanning Force Microscopy and gel electrophoresis

This work focuses on the analysis of the influence of environment on the relative biological effectiveness (RBE) of carbon ions on molecular level. Due to the high relevance of RBE for medical applications, such as tumor therapy, and radiation protection in space, DNA damages have been investigated in order to understand the biological efficiency of heavy ion radiation. The contribution of this study to the radiobiology research consists in the analysis of plasmid DNA damages induced by carbon ion radiation in biochemical buffer environments, as well as in the calculation of the RBE of carbon ions on DNA level by mean of scanning force microscopy (SFM). In order to study the DNA damages, besides the common electrophoresis method, a new approach has been developed by using SFM. The latter method allows direct visualisation and measurement of individual DNA fragments with an accuracy of several nanometres. In addition, comparison of the results obtained by SFM and agarose gel electrophoresis methods has been performed in the present study. Sparsely ionising radiation, such as X-rays, and densely ionising radiation, such as carbon ions, have been used to irradiate plasmid DNA in trishydroxymethylaminomethane (Tris buffer) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES buffer) environments. These buffer environments exhibit different scavenging capacities for hydroxyl radical (HO0), which is produced by ionisation of water and plays the major role in the indirect DNA damage processes. Fragment distributions have been measured by SFM over a large length range, and as expected, a significantly higher degree of DNA damages was observed for increasing dose. Also a higher amount of double-strand breaks (DSBs) was observed after irradiation with carbon ions compared to X-ray irradiation. The results obtained from SFM measurements show that both types of radiation induce multiple fragmentation of the plasmid DNA in the dose range from D = 250 Gy to D = 1500 Gy. Using Tris environments at two different concentrations, a decrease of the relative biological effectiveness with the rise of Tris concentration was observed. This demonstrates the radioprotective behavior of the Tris buffer solution. In contrast, a lower scavenging capacity for all other free radicals and ions, produced by the ionisation of water, was registered in the case of HEPES buffer compared to Tris solution. This is reflected in the higher RBE values deduced from SFM and gel electrophoresis measurements after irradiation of the plasmid DNA in 20 mM HEPES environment compared to 92 mM Tris solution. These results show that HEPES and Tris environments play a major role on preventing the indirect DNA damages induced by ionising radiation and on the relative biological effectiveness of heavy ion radiation. In general, the RBE calculated from the SFM measurements presents higher values compared to gel electrophoresis data, for plasmids irradiated in all environments. Using a large set of data, obtained from the SFM measurements, it was possible to calculate the survive rate over a larger range, from 88% to 98%, while for gel electrophoresis measurements the survive rates have been calculated only for values between 96% and 99%. While the gel electrophoresis measurements provide information only about the percentage of plasmids DNA that suffered a single DSB, SFM can count the small plasmid fragments produced by multiple DSBs induced in a single plasmid. Consequently, SFM generates more detailed information regarding the amount of the induced DSBs compared to gel electrophoresis, and therefore, RBE can be calculated with more accuracy. Thus, SFM has been proven to be a more precise method to characterize on molecular level the DNA damage induced by ionizing radiations.

Echtzeitsimulation großer Grafikmodelle

Die vorliegende Arbeit entstand während meiner Zeit als wissenschaftlicher Mitarbeiter im Fachgebiet Technische Informatik an der Universität Kassel. Im Rahmen dieser Arbeit werden der Entwurf und die Implementierung eines Cluster-basierten verteilten Szenengraphen gezeigt. Bei der Implementierung des verteilten Szenengraphen wurde von der Entwicklung eines eigenen Szenengraphen abgesehen. Stattdessen wurde ein bereits vorhandener Szenengraph namens OpenSceneGraph als Basis für die Entwicklung des verteilten Szenengraphen verwendet. Im Rahmen dieser Arbeit wurde eine Clusterunterstützung in den vorliegenden OpenSceneGraph integriert. Bei der Erweiterung des OpenSceneGraphs wurde besonders darauf geachtet den vorliegenden Szenengraphen möglichst nicht zu verändern. Zusätzlich wurde nach Möglichkeit auf die Verwendung und Integration externer Clusterbasierten Softwarepakete verzichtet. Für die Verteilung des OpenSceneGraphs wurde auf Basis von Sockets eine eigene Kommunikationsschicht entwickelt und in den OpenSceneGraph integriert. Diese Kommunikationsschicht wurde verwendet um Sort-First- und Sort-Last-basierte Visualisierung dem OpenSceneGraph zur Verfügung zu stellen. Durch die Erweiterung des OpenScenGraphs um die Cluster-Unterstützung wurde eine Ansteuerung beliebiger Projektionssysteme wie z.B. einer CAVE ermöglicht. Für die Ansteuerung einer CAVE wurden mittels VRPN diverse Eingabegeräte sowie das Tracking in den OpenSceneGraph integriert. Durch die Anbindung der Geräte über VRPN können diese Eingabegeräte auch bei den anderen Cluster-Betriebsarten wie z.B. einer segmentierten Anzeige verwendet werden. Die Verteilung der Daten auf den Cluster wurde von dem Kern des OpenSceneGraphs separat gehalten. Damit kann eine beliebige OpenSceneGraph-basierte Anwendung jederzeit und ohne aufwendige Modifikationen auf einem Cluster ausgeführt werden. Dadurch ist der Anwender in seiner Applikationsentwicklung nicht behindert worden und muss nicht zwischen Cluster-basierten und Standalone-Anwendungen unterscheiden.

The role of ligneous vegetation for livestock nutrition in the sub-Sahelian and Sudanian zones of West Africa: Potential effects of climate change

Climate change and variability in sub-Saharan West Africa is expected to have negative consequences for crop and livestock farming due to the strong dependence of these sectors on rainfall and natural resources, and the low adaptive capacity of crops farmers, agro-pastoralist and pastoralists in the region. The objective of this PhD research was to investigate the anticipated impacts of expected future climate change and variability on nutrition and grazing management of livestock in the prevailing extensive agro-pastoral and pastoral systems of the Sahelian and Sudanian zones of Burkina Faso. To achieve this, three studies were undertaken in selected village territories (100 km² each) in the southern Sahelian (Taffogo), northern Sudanian (Nobere, Safane) and southern Sudanian (Sokouraba) zone of the country during 2009 and 2010. The choice of two villages in the northern Sudanian zone was guided by the dichotomy between intense agricultural land use and high population density near Safane, and lower agricultural land use in the tampon zone between the village of Nobere and the National Park Kaboré Tambi of Pô. Using global positioning and geographical information systems tools, the spatio-temporal variation in the use of grazing areas by cattle, sheep and goats, and in their foraging behaviour in the four villages was assessed by monitoring three herds each per species during a one-year cycle (Chapter 2). Maximum itinerary lengths (km/d) were observed in the hot dry season (March-May); they were longer for sheep (18.8) and cattle (17.4) than for goats (10.5, p<0.05). Daily total grazing time spent on pasture ranged from 6 - 11 h with cattle staying longer on pasture than small ruminants (p<0.05). Feeding time accounted for 52% - 72% of daily time on pasture, irrespective of species. Herds spent longer time on pasture and walked farther distances in the southern Sahelian than the two Sudanian zones (p<0.01), while daily feeding time was longer in the southern Sudanian than in the other two zones (p>0.05). Proportional time spent resting decreased from the rainy (June - October) to the cool (November - February) and hot dry season (p<0.05), while in parallel the proportion of walking time increased. Feeding time of all species was to a significantly high proportion spent on wooded land (tree crown cover 5-10%, or shrub cover >10%) in the southern Sahelian zone, and on forest land (tree crown cover >10%) in the two Sudanian zones, irrespective of season. It is concluded that with the expansion of cropland in the whole region, remaining islands of wooded land, including also fields fallowed for three or more years with their considerable shrub cover, are particularly valuable pasturing areas for ruminant stock. Measures must be taken that counteract the shrinking of wooded land and forests across the whole region, including also active protection and (re)establishment of drought-tolerant fodder trees. Observation of the selection behaviour of the above herds of cattle and small ruminant as far as browse species were concerned, and interviews with 75 of Fulani livestock keepers on use of browse as feed by their ruminant stock and as remedies for animal disease treatment was undertaken (Chapter 3) in order to evaluate the consequence of climate change for the contribution of browse to livestock nutrition and animal health in the extensive grazing-based livestock systems. The results indicated that grazing cattle and small ruminants do make considerable use of browse species on pasture across the studied agro-ecological zones. Goats spent more time (p<0.01) feeding on browse species than sheep and cattle, which spent a low to moderate proportion of their feeding time on browsing in any of the study sites. As far as the agro-ecological zones were concerned, the contribution of browse species to livestock nutrition was more important in the southern Sahelian and northern Sudanian zone than the southern Sudanian zone, and this contribution is higher during the cold and hot dry season than during the rainy season. A total of 75 browse species were selected on pasture year around, whereby cattle strongly preferred Afzelia africana, Pterocarpus erinaceus and Piliostigma sp., while sheep and goats primarily fed on Balanites aegyptiaca, Ziziphus mauritiana and Acacia sp. Crude protein concentration (in DM) of pods or fruits of the most important browse species selected by goats, sheep and cattle ranged from 7% to 13% for pods, and from 10% to 18% for foliage. The concentration of digestible organic matter of preferred browse species mostly ranged from 40% to 60%, and the concentrations of total phenols, condensed tannins and acid detergent lignin were low. Linear regression analyses showed that browse preference on pasture is strongly related to its contents (% of DM) of CP, ADF, NDF and OM digestibility. Interviewed livestock keepers reported that browse species are increasingly use by their grazing animals, while for animal health care use of tree- and shrub-based remedies decreased over the last two decades. It is concluded that due to climate change with expected negative impact on the productivity of the herbaceous layer of communal pastures browse fodder will gain in importance for animal nutrition. Therefore re-establishment and dissemination of locally adapted browse species preferred by ruminants is needed to increase the nutritional situation of ruminant stock in the region and contribute to species diversity and soil fertility restoration in degraded pasture areas. In Chapter 4 a combination of household surveys and participatory research approaches was used in the four villages, and additionally in the village of Zogoré (southern Sahelian zone) and of Karangasso Vigué (northern Sudanian zone) to investigate pastoralists’ (n= 76) and agro-pastoralists’ (n= 83) perception of climate change, and their adaptation strategies in crop and livestock production at farm level. Across the three agro-ecological zones, the majority of the interviewees perceived an increase in maximum day temperatures and decrease of total annual rainfall over the last two decades. Perceptions of change in climate patterns were in line with meteorological data for increased temperatures while for total rainfall farmers’ views contrasted the rainfall records which showed a slight increase of precipitation. According to all interviewees climate change and variability have negative impacts on their crop and animal husbandry, and most of them already adopted some coping and adaptation strategies at farm level to secure their livelihoods and reduce negative impacts on their farming system. Although these strategies are valuable and can help crop and livestock farmers to cope with the recurrent droughts and climate variability, they are not effective against expected extreme climate events. Governmental and non-governmental organisations should develop effective policies and strategies at local, regional and national level to support farmers in their endeavours to cope with climate change phenomena; measures should be site-specific and take into account farmers’ experiences and strategies already in place.

Interrelatedness of grazing livestock with vegetation parameters and farmers’ livelihoods in the Mahafaly region, southwestern Madagascar

The study aims to get deeper insight into the highly extensive system of animal husbandry in the Mahafaly region of southwestern Madagascar. It tries to understand the major drivers for pastoral dynamics, land and resource use along a gradient in altitude and vegetation to consider the area’s high spatial and temporal heterogeneity. The study also analyzes the reproductive performance of local livestock as well as the owners’ culling strategies to determine herd dynamics, opportunities for economic growth, and future potential for rural development. Across seasons, plateau herds from both livestock species covered longer distances (cattle 13.6±3.02 km, goats 12.3±3.48 km) and were found further away from the settlements (cattle 3.1±0.96 km, goats 2.8±0.98 km) than those from the coastal plain (walking_dist: cattle 9.5±3.25 km, goats 9.2±2.57 km; max_dist: cattle 2.6±1.28 km, goats 1.8±0.61 km). Transhumant cattle were detected more vulnerable through limited access to pasture land and water resources compared to local herds. Seasonal water shortage has been confirmed as a key constraint on the plateau while livestock keeping along the coast is more limited by dry season forage availability. However, recent security issues and land use conflicts with local crop farmers are gaining importance and force livestock owners to adapt their traditional grazing management, resulting in spatio-temporal variation of livestock numbers and in the impending risk of local overgrazing and degradation of rangelands. Among the 133 plant species consumed by livestock, 13 were determined of major importance for the animals’ nutrition. The nutritive value and digestibility of the natural forage, as well as its abundance in the coastal zone, substantially decreased over the course of the dry season and emphasized the importance of supplementary forage plants, in particular Euphorbia stenoclada. At the same time, an unsustainable utilization and overexploitation of its wild stocks may raise the pressure on the vegetation and pasture resources within the nearby Tsimanampetsotsa National Park. Age at first parturition was 40.5±0.59 months for cattle and 21.3±0.63 months for goats. Both species showed long parturition intervals (cattle 24.2±0.48 months, goats 12.4±0.30 months), mostly due to the maintenance of poorly performing breeding females within the herds. Reported offspring mortality, however, was low with 2.5% of cattle and 18.8% of goats dying before reaching maturity. The analysis of economic information revealed higher than expected market dynamics, especially for zebus, resulting in annual contribution margins of 33 € per cattle unit and 11 € per goat unit. The application of the PRY Herd Life model to simulate herd development for present management and two alternate scenarios confirmed the economic profitability of the current livestock system and showed potential for further productive and economic development. However, this might be clearly limited by the region’s restricted carrying capacity. Summarizing, this study illustrates the highly extensive and resources-driven character of the livestock system in the Mahafaly region, with herd mobility being a central element to cope with seasonal shortages in forage and water. But additional key drivers and external factors are gaining importance and increasingly affect migration decisions and grazing management. This leads to an increased risk of local overgrazing and overexploitation of natural pasture resources and intensifies the tension between pastoral and conservation interests. At the same time, it hampers the region’s agronomic development, which has not yet been fully exploited. The situation therefore demonstrates the need for practical improvement suggestions and implication measures, such as the systematic forestation of supplemental forage plant species in the coastal zone or a stronger integration of animal husbandry and crop production, to sustain the traditional livestock system without compromising peoples’ livelihoods while at the same time minimizing the pastoral impact on the area’s unique nature and environment.