This study analyzes the available radar evidence in order to describe the morphology of channel networks around the north polar seas of Titan. Critical flow depths necessary to entrain water-ice grains, and denudation rates for a north polar channel network are discussed. The results indicate that channel networks on Titan have similar morphologies to channel networks cut by water on Earth. We also find that water-ice sediment should be readily entrained in the headwaters and downstream sections of the analyzed Titanian basin, given sufficient flow depths of liquid hydrocarbons. Also, the importance of slope and the elevated topography of the highlands surrounding the polar lakes are considered, as well as potential formation theories for the elevated highlands and low-lying maria that dominate the north polar region.

Dans le cadre des activités de maintenance des centrales nucléaires, les personnes intervenant sur des chantiers en zone contrôlée doivent effectuer des mesures de contamination surfacique sur leurs outils, gants, sur tenue de travail et sur les parties de leur corps susceptible d’être contaminées (cou et tête par exemple). Or, les mesures de contamination surfacique bêta ne peuvent pas toujours être réalisées au plus près des chantiers. Le bruit de fond gamma présent à ces endroits étant élevé et fluctuant, ce dernier perturbe les appareils utilisés habituellement pour la mesure de contamination surfacique. L’objectif principal de ce travail était de concevoir un appareil de mesure adapté à la détection de contamination surfacique bêta de quelques Bq/cm2 (typiquement < 4 Bq/cm2), dans une ambiance gamma de quelques dizaines de µSv/h (typiquement < 100 µSv/h) et fluctuante (typiquement de l’ordre de 30% en 1 seconde). / In the framework of the nuclear power plants maintenance, the onsite workers incontrolled areas must performed some surface contamination controls of their tools, gloves, workingsuits and over their body parts which may be contaminated (neck and head for instance). However,surface beta contamination measurements can’t always been done as close as possible of the working location. The onsite ambient gamma background, being high and fluctuating, may disturb the radiation protection devices commonly used for surface contamination measurements.The main goal of this work was to conceive a radiation protection device adapted to the betasurface contamination of about a few Bq/cm2 (< 4Bq/cm2 typicaly) in a fluctuating (typicaly 30%variation per second) ambient gamma background of a few μSv/h (typicaly <100 μSv/h).

This research explores constructions and understandings of fluctuating or recurring impairments in Higher Education in the UK. It considers ways in which institutional discourses within one UK University have shaped policy and provision for disabled students, and how students with fluctuating or recurring impairments negotiate and enact identities in this context. For many students, impairments such as chronic fatigue syndrome (CFS)/ myalgic encephalomyelitis (ME), epilepsy or diabetes, for example, have the potential to vary in intensity, and thus impact, on participation in learning activities and on self-perception/ identity. With increasing disclosure, yet limited recognition, of such types of impairment comes a need for institutions to better understand changing impact in terms of inclusion and in observing anticipatory aspects of legislation, as well as furthering insight into how student identities are negotiated and constructed in an educational context. This research uses a social constructionist framework to explore constructions and subjectivities as regards fluctuating or recurring impairments, and comprises both staff and student perspectives. The staff perspective is based on the thematic narrative analysis of interviews with three members of staff, and is presented in conjunction with an example of institutional policy to highlight discourses drawn upon in constructing disability and disabled students. The impact of these discourses on institutional constructions and practice is key to the analysis. The student perspective is based on two phases of data collection: firstly, 24 semi-structured interviews with students who self-described a fluctuating or recurring impairment; and secondly, five students’ responses to six bi-weekly emails over the course of one academic trimester (January – April 2011). Summary data from the first phase is used to frame discussion on issues raised by students regarding institutional constructions and support. A ‘hybrid’ narrative analysis framework incorporating positioning analysis as well as both ‘big’ and ‘small stories’ has been used in analysing the phase two data. The approach considers the influence of institutional discourses on how students are positioned institutionally and position themselves, as well as ways in which performances of identity may be shaped. The thesis concludes by considering the implications of the research outcomes for Higher Education. In so doing, it notes the significance of policy implementation and cultural change, and makes recommendations for areas of focus in raising institutional awareness of fluctuating or recurring impairments within existing constructions of disability.

Fluorescence in blue light (FLU) ist ein negativer Feedbackregulator der Chlorophyllbiosynthese, welcher an der Dunkelrepression der 5-Aminolävulinsäure (ALA)-Synthese beteiligt ist. FLU ist Teil eines Komplexes, der die Enzyme umfasst, welche an der Katalyse der finalen Schritte der Chlorophyllbiosynthese beteiligt sind. Drei funktionelle Domänen wurden für das Arabidopsis FLU Protein postuliert: eine Tetratricopeptid-Wiederholungsdomäne (TPR) befindet sich am C-Terminus; eine Transmembrandomäne (TM) ist am N-Terminus lokalisiert; eine Coiled-coil-Domäne (linker) liegt dazwischen. Die TPR-Domäne von FLU Domäne interagiert mit dem C-terminalen Ende der Glutamyl-tRNA Reduktase (GluTR), dem geschwindigkeitsbestimmenden Enzym der ALA-Synthese. Diese Arbeit zur Erweiterung des Wissen über die Funktion von FLU im Licht sowie über die Rolle der funktionellen Domänen von FLU bei der Inaktivierung der ALA-Synthese bei. / Fluorescence in blue light (FLU), a negative feedback regulator of chlorophyll biosynthesis, is involved in dark repression of 5-aminolevulinic acid (ALA) synthesis. FLU is part of a complex comprising the enzymes catalyzing the final steps of chlorophyll synthesis. Three functional domains were proposed in the Arabidopsis FLU protein: a tetratricopeptide repeat (TPR) domain is at the C-terminus; a transmembrane domain (TM) is at the N-terminus; a coiled-coil domain (linker) is in between. The TPR(FLU) domain interacts with the C-terminal end of glutamyl-tRNA reductase (GluTR), the rate-limiting enzyme of ALA synthesis. This thesis contributes to the extended knowledge about the function of FLU in light as well as the role of the structural domains of FLU in the inactivation of ALA synthesis.

Les amibes sociales sont des organismes eucaryotes présents dans le sol de presque toutes les zones climatiques. Ils sont remarquables pour leur passage d'un état unicellulaire à un état multicellulaire en réponse à la carence en nutriments. En période de carence, des millions de cellules forment des agrégats qui constituent chacun un nouvel organisme multicellulaire, contenant des spores, cellules reproductives, et des cellules de tige, cellules mortes qui favorisent la dispersion des spores. Ce comportement, de par le coût payé par les cellules de tige, a permis d'utiliser les amibes sociales en tant que système-modèle pour aborder des questions majeures de l'évolution de la coopération et de la multicellularité. Dans cette étude, nous examinons trois aspects différents du comportement des amibes sociales; agrégation, non-agrégation et compétition, et nous analysons comment ces aspects contribuent à notre compréhension de la coopération chez les amibes et systèmes microbiens en général.Nous avons exploré le fait bien connu mais négligé qu'en phase de carence nutritive, une fraction des cellules ne participent pas à la formation des agrégats pas et ne sont pas engagées dans le développement multicellulaire. Nous décrivons les facteurs phénotypiques et génétiques qui déterminent la fraction de cellules hors-agrégats chez D. discoideum. Les deux stratégies, d'agrégation et de non-agrégation, sont coûteuses ou bénéfiques d'un point de vue évolutif selon la durée de la phase de carence. Nous avons développé un modèle pour simuler ce processus. Nous proposons que le partitionnement de la population dans des états unicellulaire et multicellulaire est adaptative dans des environnements fluctuants avec une durée imprévisible des périodes de carence nutritive. Les amibes sociales sont donc situées à l'intersection de deux thèmes émergents en évolution microbienne, la coopération et le "placement des paris".Dans la deuxième partie, nous proposons un nouveau cadre pour aborder les observations a priori contradictoires de la diversité génétique dans les populations naturelles d'amibes sociales et une faible diversité nécessaire pour la coopération. Nous proposons que le cycle de vie complexe des amibes sociales fournit plusieurs points de compétition qui peut servir à la fois comme stabilisateur de la diversité et de la coopération. Nous explorons cette hypothèse expérimentalement avec un modèle en analysant la compétition entre 6 isolats naturels de D. discoideum. Notre simulation-modèle indique que la compétition à différents stades du cycle de vie peut conduire à l'exclusion des "gagnants sociaux". Toutefois nous n'avons pas réussi à expliquer la coexistence à long terme de souches génétiquement distinctes. Bien que préliminaires, nos résultats soulignent l'importance d'intégrer l'écologie des espèces dans les études de coopération microbienne.Enfin, nous nous concentrons sur une nouvelle dynamique d'agrégation chez P. pallidum observée dans notre laboratoire. L'agrégation est un processus au niveau de la population au cours duquel la population se divise en nombreuses sous-populations (agrégats) qui font face à la sélection de manière indépendante. Un tel fractionnement de la population peut avoir de fortes conséquences évolutives du point de vue de la coopération qui n'ont pas encore été explorées expérimentalement. Nous décrivons la dynamique des populations qualitativement et proposons plusieurs mesures quantitatives de partitionnement de la population en agrégats. Nos résultats préliminaires suggèrent qu'il existe une préférence pour les agrégats d'une certaine taille, mais qu'il n'existe aucune organisation spatiale des agrégats. / Social amoebae are eukaryotic organisms that inhabit soil of almost every climate zone. They are remarkable for their switch from unicellularity to multicellularity as an adaptation to starvation. When starved, millions of single cells aggregate and form a multicellular fruiting body, which contains reproductive spore cells and dead stalk cells, which help in spore dispersion. This costly behavior made social amoebae a model system for addressing major questions of the evolution of cooperation and multicellularity. In this study we look at three different aspects of social amoebae behavior; aggregation, non-aggregation and competition, and ask how they contribute to our understanding of cooperation in social amoebae and microbial systems in general.We explored the known but neglected observation that, upon starvation, not all cells aggregate and engage in multicellular development. We describe phenotypically and genetically non-aggregating cell proportion in D. discoideum species. Both aggregating and non-aggregating strategy are costly or beneficial depending on duration of starvation. With our computational model we propose that partitioning the population into unicellular and multicellular states is adaptive in fluctuating environments with unpredicted duration of starvation periods. Social amoebae may therefore lie at the intersection of cooperation and bet-hedging. In the second part, we provide a new framework for addressing the contrasting observations of high genetic diversity in natural populations of social amoebae and experimentally suggested low diversity-high relatedness required for cooperation. We propose that complex life cycle of social amoebae provides multiple competition points that can possibly play an important role in maintaining diversity and cooperation. We explore this experimentally and computationally by looking at competition over the whole life cycle between 6 natural isolates of D. discoideum. Our simulation model indicates that competition at different stages of the life cycle can lead to exclusion of “social winners”. Though we failed to explain strain coexistence. Although preliminary, our results emphasize the importance of integrating species ecology in cooperative studies.Finally, we focus on a new aggregation dynamics in P. pallidum species observed in our lab. Aggregation is a population level process during which population gets divided into numerous subpopulations/aggregates that face selection independently. Such population partitioning can have strong evolutionary consequences on cooperation that have not yet been explored experimentally. We describe the population dynamics qualitatively and propose several quantitative measurements of population partitioning into aggregates. Our preliminary results suggest that there is a preference for aggregates of certain size, but there is no spatial organization of aggregates.

This investigation address the effect that pressure, p, and temperature, T, have on 4f-states of the rare-earth elements in the isostructural YbRh2Si2, EuCo2Ge2, and EuCu2Ge2 compounds. Upon applying pressure, the volume of the unit cell reduces, enforcing either the enhancement of the hybridization of the 4f-localized electrons with the ligand or a change in the valence state of the rare-earth ions. Here, we probe the effect of a pressure-induced lattice contraction on these system by means of electrical resistivity, from room temperature down to 100 mK. At ambient pressure, the electrical resistivity of YbRh2Si2 shows a broad peak at 130 K related to the incoherent scattering on the ground state and the excited crystalline electrical field (CEF) levels. At T_N = 70 mK, YbRh2Si2 undergoes a magnetic phase transition. Upon applying pressure up to p_1 = 4 GPa , T_N increases monotonously while the peak in the electrical resistivity is shifted to lower temperatures. For p &amp;lt; p_1 a different behavior is observed; namely, T_N depends weakly on the applied pressure and a decomposition of the single peak in the electrical resistivity into several shoulders and peaks occurs. Above p_2 = 9 GPa, the electrical resistivity is significantly reduced for T &amp;lt; 50 K and this process is accompanied by a sudden enhancement of T_N. Thus, our results confirm the unexpected behavior of the magnetization as function of pressure reported by Plessel et al. The small value of the magnetic ordering temperature for p &amp;lt; p_2 and the strength of the mechanism that leads to the peaks and shoulders in the electrical resistivity suggest that the f-electrons are still screened by the conduction electrons. Therefore, the observed behavior for pressures lower than p_2 might be a consequence of the competition of two different types of magnetic fluctuations (seemingly AFM and FM). Furthermore, the results suggest that a sudden change of the CEF scheme occurs at pressures higher than p_1, which would have an influence on the ground state. Additionally, a comparison of the pressure dependent features in the electrical resistivity of YbRh2Si2 with similar maxima in other isostructural YbT2X2 (T = transition metal; X = Si or Ge) compounds was performed. For the comparison, a simple relation that considers the Coqblin-Schrieffer model and the hypothesis of Lavagna et al. is proposed. A systematic behavior is observed depending on the transition metal; namely, it seems that the higher the atomic radii of the T-atom the smallest the pressure dependence of the maximum in the electrical resistivity, suggesting a weaker coupling of localized- and conduction-electrons. It is also observed that an increase in the density of conduction electrons reduces the pressure dependence of the characteristic Kondo temperature. The mechanism responsible for the sudden enhancement of T_N in YbRh2Si2 at about p_2 is still unknown. However two plausible scenarios are discussed. The Eu-ions in EuCo2Ge2 and EuCu2Ge2 have a divalent character in the range 100 mK &amp;lt; T &amp;lt; 300 K. Therefore, these systems order magnetically at T_N = 23 K and T_N = 12 K, respectively. The studies performed on EuCo2Ge2 and EuCu2Ge2 as a function of pressure suggest that a change to a non-magnetic trivalent state of the Eu-ions might occur at zero temperature for pressures higher than 3 GPa and 7 GPa, respectively. A common and characteristic feature on EuCo2Ge2 and EuCu2Ge2 is the absence of a clear first order transition from the divalent to the trivalent state of the Eu-ions at finite temperature for p &amp;gt; 3 GPa and for p &amp;gt; 7 GPa, respectively. In other isostructural Eu-based compounds, a discontinuous and abrupt change in the thermodynamic and transport properties associated to the valence transition of the Eu-ions is typically observed at finite temperatures. In contrast, the electrical resistivity of EuCo2Ge2 and EuCu2Ge2 changes smoothly as a function of pressure and temperature. The analysis of the the electrical resistivity of EuCo2Ge2 suggest that a classical critical point might be close to the AFM-ordered phase, being a hallmark of this compound. The overall temperature dependence of the the electrical resistivity of EuCo2Ge2 changes significantly at 3 GPa; therefore, it seems that the system suddenly enters to a T-dependent valence-fluctuating regime. Additionally, the pressure-dependent electrical-resistivity isotherms show a step-like behavior. Thus, it is concluded that discontinuous change of the ground state might occur at 3 GPa. The electrical resistivity of EuCu2Ge2 at high pressure is characterized by a negative logarithmic T-dependence in the pressure range 5 GPa &amp;lt; p &amp;lt; 7 GPa for T &amp;gt; T_N and by a broad peak in the pressure dependent residual resistivity, whose maximum is located at 7.3 GPa. The first behavior resembles the incoherent scattering process typical for an exchange coupling mechanism between the localized electrons and the ligand. This and the peak effect in the local 4f susceptibility observed in NMR measurements are consistent with such a coupling mechanism. Thus, it would be for the first time that a dense Eu-based compound like EuCu2Ge2 show such a behavior. Combining the results of the experiment performed at high pressures on EuCu2Ge2 with the studies performed in the EuCu2(Ge1-xSix)2 series, a crossover from an antiferromagnetically ordered state into a Fermi-liquid state for pressures higher than 7.3 GPa may be inferred from the analysis. Therefore, it may be possible that the sudden depopulation of 4f-level occur mediated by quantum fluctuation of the charge due to a strong Coulomb repulsion between the localized-electrons and the ligand. This phenomenon would explain the broad peak in the residual resistivity. To our knowledge, this would be the first Eu-based compound, isostructural to ThCr2Si2, that show such a transition as function of pressure at very low temperatures.

This thesis investigates the period in Judah which took place precisely a century between the death ofHezekiah (687 BCE) and the final fall of Jerusalem (587 BCE) Seldom has a nation experienced so many dramatically sudden reversals of fortune in so relatively short a time. Throughout the first half of the seventh century BCE the Assyrian empire reigned supreme. In the second half, in rapid succession, Judah, as a vassal, experienced periods of independence and of subjection, first to Egypt, then to Babylonia, before finally destroying herself in a futile rebellion against the latter. The aim of the thesis was to set Judah in the global context and investigate the role she played. To this end the Great Powers, namely Assyria, Egypt and Babylonia were surveyed, as well as were the Small Powers, like Judah, Phoenicia and the Transjordanian states, and the relationships probed. The thesis traces the life of the wicked but extraordinarily successful King Manasseh, and his equally reprobate son, Amon, who was brutally murdered by his servants, and was avenged by 'the people of the land'. Josiah is the only monarch who fits the Deuteronomistic requirements of a good king. Religious and national reform generally go hand in hand with politics, and the cultic reform and centralization of the cult characterise his reign. · With the fall of Assyria, the temporary surge into prominence by Egypt and the tragic death of Josiah in 609 BCE, Judah experienced radical political fluctuations and with them alternate subjugation by, and rebellion against, each of the major powers. Inexperienced leadership and a situation of dual kings, followed Josiah's death. The rapidly changing international scene demanded of the rulers of Judah skillful manoeuvring and exceptional adaptability, and frequently confronted them with ominous political situations. Judaean leaders and the puppet King Zedekiah, propped up by false prophets, failed to grasp the shift in the balance of power, and clung to questionable Egyptian aid against the new world power, Babylonia. Highly vulnerable and left in the lurch, Jerusalem faced protracted siege and famine in Jerusalem, destruction ofthe Temple, and deportation ofthe cream ofher people. / Classics and Modern European Languages / D. Litt. et Phil. (Judaica)

En dépit des taux élevés de mortalité infantile dans les populations du passé, les sujets décédés en période périnatale ont longtemps été délaissés dans les travaux anthropologiques et paléoanthropologiques. Alors que les analyses biologiques portant sur les individus adultes intègrent l’étude de la variabilité comme une composante majeure, rares sont celles permettant de replacer un individu décédé en période périnatale dans le cadre de la variabilité individuelle ou populationnelle de cette classe d’âge. Le présent travail se propose ainsi d’investir le sujet de la diversité métrique et non-métrique des sujets décédés entre 22 et 48 semaines d’aménorrhée à partir de l’étude biologique de 116 sujets de trois collections archéologiques (une kerma et deux médiévales et modernes) et d’une collection actuelle virtuelle comportant 364 individus. Un premier axe de recherche caractérise la variabilité des corpus dans ses composantes intra-individuelles, inter-individuelles, populationnelles, ainsi que du point de vue des corrélations à l’âge au décès. Un second axe de recherche vise à identifier des caractères permettant d’estimer l’état de morbidité et de vitalité à la naissance de l’individu, donnée déterminante pour le statut du sujet dans la société. Pour le premier axe, l’étude révèle des différences de conformation selon l’âge au décès et les groupes populationnels, de même que l’existence d’asymétries directionnelles et fluctuantes. Les résultats vont ensuite dans le sens d’une forte proximité biologique pour le groupe kerma, traduisant potentiellement une certaine endogamie, au contraire du groupe médiéval et moderne dont la diversité plus importante pourrait refléter des facteurs socio-géographiques ou séculaires. Le second axe de recherche a permis de souligner que la mécano-sensibilité des régions d’insertion musculaire apparaît comme un nouveau paramètre à considérer pour discerner les sujets ayant survécu à la naissance. L’étude de la collection kerma livre également la première identification en contexte archéologique d’un critère de morbidité spécifique, la côte surnuméraire cervicale. Enfin, le croisement des analyses biologiques et des données archéologiques de la nécropole 8B-51 de l’île de Saï, permet d’appréhender et de discuter les traitements funéraires dévolus à la classe d’âge périnatale au Kerma classique. / Despite the high rates of child mortality in past populations, subjects deceased in perinatal period were often neglected in bioarchaeological and paleoanthropology studies. Unlike biological analysis on adults, investigations on newborns rarely include individual or populational variability comparisons as a major component. In the present work, we will focus on metrical and non-metrical diversity of subject deceased between 22 and 48 amenorrhea weeks, based on the biological study of 116 subjects from three archaeological collections (one kerma and two medieval and modern) and one current virtual collection with 364 individuals. The first research axis characterizes the intra-individual, inter-individual and populational variability, and differences by age at death in both samples. The second line of research aims to identify criteria making it possible to estimate individual morbidity and live birth on dry bones, informations that are needed to understand the child’s position in society. Biological studies reveal for the first research axis shape differences by age at death and populations, as well as the existence of directional and fluctuating asymmetries. Results provide evidences of strong biological proximity in the kerma group, potentially indicating of endogamy. On the contrary, the diversity of the medieval and modern group appears broader and could reflect socio-geographical factors or secular trends. The second line of research reveals the mechanical sensitivity of muscular insertions as a key parameter for tracking of live-born subjects. The study of the kerma collection provides the first archaeological identification of the supernumerary cervical rib, detected as a morbidity criterion in perinatal period. Lastly, crossing of biological and archaeological data on the 8B-51 necropolis provides an interpretative framework for funerary treatments dedicated to the perinatal age group in Classic Kerma.

The general goal of this research was to understand the agronomic and physiological changes of a lucerne crop in distinct physical radiation environments and to verify the potential of lucerne to grow under shaded conditions. To achieve this, the research was conducted in four main steps: (i) firstly, experimental data collection in the field using two artificial shade materials (shade cloth and wooden slats) under inigated and non-irrigated conditions; (ii) a second experiment with data collection in a typical temperate dryland agroforestry area under non-irrigated conditions; (iii) generation of a light interception sub-model suitable for shaded crops and (iv) a linkage between the light interception sub-model and a canopy photosynthesis model for agroforestry use. In experiments 1 and 2, lucerne crop was exposed to 6 different light regimes: full sunlight (FS), shade cloth (FS+CL), wooden slats (FS+SL), trees (T), trees+cloth (T +CL) and trees+slats (T+SL). The FS+SL structure produced a physical radiation environment (radiation transmission, radiation periodicity and spectral composition) that was similar to that observed in the agroforestry site (f). The mean annual photosynthetic photon flux density (PPFD) was 41 % under the FS+CL, 44% under FS+SL and 48% under T compared with FS in clear sky conditions. Plants were exposed to an intermittent (sun/shade) regime under both FS+SL and T, whereas under FS+CL the shaded light regime was continuous. The red to far-red (RIFR) ratio measured during the shade period under the slats was 0.74 and under the trees was 0.64. However, R/FR ratio increased to 1.26 and 1.23 during the illuminated period under FS+SL and T, respectively, and these were equivalent to the ratio of 1.28 observed under the FS+CL and 1.31 in FS. The radiation use efficiency (RUE) of shoots increased under the 5 shaded treatments compared with full sunlight. The pattern of radiation interception was unchanged by radiation flux, periodicity and spectral composition and all treatments had a mean extinction coefficient of 0.82. However, the magnitude of the decrease in canopy growth was less than those in PPFD transmissivity. The mean lucerne annual dry matter (DM) yield was 17.5 t ha⁻¹ in FS and 10 t ha⁻¹ under the FS+CL, FS+SL and T regimes. This declined to 3.4 t DM ha⁻¹ under T+CL (22% PPFD transmissvity) and 4.1 t DM ha⁻¹ under T+SL (23% transmissivity). A similar pattern of response was observed for leaf net photosynthesis (Pn) rates under the shade treatments compared with full sun. In addition, spectral changes observed under the trees and slats affected plant motphology by increasing the number of long stems, stem height and internode length compared with full sunlight. Thus, there were two main explanations for the increase in RUE under shade compared with full sun: (i) preferential partition of assimilates to shoot rather than root growth and/or (ii) leaves under shade were still operating at an efficient part of the photosynthetic light curve. The changes proposed for the canopy Pn model were appropriate to simulate the radiation environment of an agroforestry system. However, the model underestimated DM yields under the continuous and intermittent shade regimes. These were considered to be mainly associated with plant factors, such as overestimation in maintenance respiration and partitioning between shoots and roots in shade and the intermittency light effect on leaf Pn rates. Further investigation in these topics must be addressed to accurately predict crop yield in agroforestry areas. Overall, the lucerne crop responded typically as a sun-adapted plant under shade. It was concluded that lucerne yield potential to grow under intermediate shade was superior to most of C3 pastures previously promoted in the literature.

The aim of this thesis is to investigate the dynamical behaviors of spatially extended systems with fluctuating time delays. In recent years, the study of spatially extended systems and systems with fluctuating delays has experienced a fast growth. In ubiquitous natural and laboratory situations, understanding the action of time-delayed signals is a crucial for understanding the dynamical behavior of these systems. Frequently, the length of the delay is found to change with time. Spatially extended systems are widely studied in many fields, such as chemistry, ecology, and biology. Self-organization, turbulence, and related nonlinear dynamic phenomena in spatially extended systems have developed into one of the most exciting topics in modern science. The first part of this thesis considers the discrete system. Diffusively coupled map lattices with a fluctuating delay are used in the study. The uncoupled local dynamics of the considered system are represented by the delayed logistic map. In particular, the influences of diffusive coupling and fluctuating delay are studied. To observe and understand the influences, the results for the considered system are compared with coupled map lattices without delay and with a constant delay as well as with the uncoupled logistic map with fluctuating delays. Identifying different patterns, determining the existence of traveling wave solutions, and specifying the fully synchronized stable state are the focus of this part of the study. The Lyapunov exponent, the master stability function, spectrum analysis, and the structure factor are used to characterize the different states and the transitions between them. The second part examines the continuous system. The delay is introduced into the reactionterm of the Fisher-KPP equation. The focus of this part of study is the time-delay-induced Turing instability in one-component reaction-diffusion systems. Turing instability has previously only been found in multiple-component reaction-diffusion systems. However, this work demonstrates with the help of the stability exponent that fluctuating delay can result in Turing instability in one-component reaction-diffusion systems as well. / Ziel der vorliegenden Arbeit ist die Untersuchung der Einflüsse der zeitlich fluktuierenden Verzögerungen in räumlich ausgedehnten diffusiven Systemen. Durch den Vergleich von Systemen mit konstanter Verzögerung bzw. Systemen ohne räumliche Kopplung erhält man ein tieferes Verständnis und eine bessere Beschreibungsweise der Dynamik des räumlich ausgedehnten diffusiven Systems mit fluktuierenden Verzögerungen. Im ersten Teil werden diskrete Systeme in Form von diffusiven Coupled Map Lattices untersucht. Als die lokale iterierte Abbildung des betrachteten Systems wird die logistische Abbildung mit Verzögerung gewählt. In diesem Teil liegt der Fokus auf Musterbildung, Existenz von Multiattraktoren und laufenden Wellen sowie der Möglichkeit der vollen Synchronisation. Masterstabilitätsfunktion, Lyapunov Exponent und Spektrumsanalyse werden benutzt, um das dynamische Verhalten zu verstehen. Im zweiten Teil betrachten wir kontinuierliche Systeme. Hier wird die Fisher-KPP Gleichung mit Verzögerungen im Reaktionsteil untersucht. In diesem Teil liegt der Fokus auf der Existenz der Turing Instabilität. Mit Hilfe von analytischen und numerischen Berechnungen wird gezeigt, dass bei fluktuierenden Verzögerungen eine Turing Instabilität auch in 1-Komponenten-Reaktions-Diffusionsgleichungen gefunden werden kann