937 resultados para McNeill, Donald: New Europe: imagined spaces
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In a previous paper, we connected the phenomenological noncommutative inflation of Alexander, Brandenberger and Magueijo [ Phys. Rev. D 67 081301 (2003)] and Koh and Brandenberger [ J. Cosmol. Astropart Phys. 2007 21 ()] with the formal representation theory of groups and algebras and analyzed minimal conditions that the deformed dispersion relation should satisfy in order to lead to a successful inflation. In that paper, we showed that elementary tools of algebra allow a group-like procedure in which even Hopf algebras (roughly the symmetries of noncommutative spaces) could lead to the equation of state of inflationary radiation. Nevertheless, in this paper, we show that there exists a conceptual problem with the kind of representation that leads to the fundamental equations of the model. The problem comes from an incompatibility between one of the minimal conditions for successful inflation (the momentum of individual photons being bounded from above) and the Fock-space structure of the representation which leads to the fundamental inflationary equations of state. We show that the Fock structure, although mathematically allowed, would lead to problems with the overall consistency of physics, like leading to a problematic scattering theory, for example. We suggest replacing the Fock space by one of two possible structures that we propose. One of them relates to the general theory of Hopf algebras (here explained at an elementary level) while the other is based on a representation theorem of von Neumann algebras (a generalization of the Clebsch-Gordan coefficients), a proposal already suggested by us to take into account interactions in the inflationary equation of state.
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BACKGROUND: Bat trypanosomes have been implicated in the evolutionary history of the T. cruzi clade, which comprises species from a wide geographic and host range in South America, Africa and Europe, including bat-restricted species and the generalist agents of human American trypanosomosis T. cruzi and T. rangeli. METHODS: Trypanosomes from bats (Rhinolophus landeri and Hipposideros caffer) captured in Mozambique, southeast Africa, were isolated by hemoculture. Barcoding was carried out through the V7V8 region of Small Subunit (SSU) rRNA and Fluorescent Fragment Length barcoding (FFLB). Phylogenetic inferences were based on SSU rRNA, glyceraldehyde phosphate dehydrogenase (gGAPDH) and Spliced Leader (SL) genes. Morphological characterization included light, scanning and transmission electron microscopy. RESULTS: New trypanosomes from bats clustered together forming a clade basal to a larger assemblage called the T. cruzi clade. Barcoding, phylogenetic analyses and genetic distances based on SSU rRNA and gGAPDH supported these trypanosomes as a new species, which we named Trypanosoma livingstonei n. sp. The large and highly polymorphic SL gene repeats of this species showed a copy of the 5S ribosomal RNA into the intergenic region. Unique morphological (large and broad blood trypomastigotes compatible to species of the subgenus Megatrypanum and cultures showing highly pleomorphic epimastigotes and long and slender trypomastigotes) and ultrastructural (cytostome and reservosomes) features and growth behaviour (when co-cultivated with HeLa cells at 37°C differentiated into trypomastigotes resembling the blood forms and do not invaded the cells) complemented the description of this species. CONCLUSION: Phylogenetic inferences supported the hypothesis that Trypanosoma livingstonei n. sp. diverged from a common ancestral bat trypanosome that evolved exclusively in Chiroptera or switched at independent opportunities to mammals of several orders forming the clade T. cruzi, hence, providing further support for the bat seeding hypothesis to explain the origin of T. cruzi and T. rangeli.
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We present a new approach to perform calculations with the certain standard classes in cohomology of the moduli spaces of curves. It is based on an important lemma of Ionel relating the intersection theoriy of the moduli space of curves and that of the space of admissible coverings. As particular results, we obtain expressions of Hurwitz numbers in terms of the intersections in the tautological ring, expressions of the simplest intersection numbers in terms of Hurwitz numbers, an algorithm of calculation of certain correlators which are the subject of the Witten conjecture, an improved algorithm for intersections related to the Boussinesq hierarchy, expressions for the Hodge integrals over two-pointed ramification cycles, cut-and-join type equations for a large class of intersection numbers, etc.
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This thesis is aimed at analysing EU external relations from the perspective of the promotion of the rule of law in order to evaluate the effectiveness and consistency of its action within the international community. The research starts with an examination of the notion of the rule of law from a theoretical point of view. The first chapter initially describes the historical-political evolution of the establishment of the notion of the rule of law. Some of the most significant national experiences (France, the UK, Germany and Austria) are discussed. Then, the focus is put on the need to propose interpretations which explain the grounds of the rule of law, by highlighting the different formal and substantive interpretations. This philosophical-historical analysis is complemented by a reconstruction of how the notion of the rule of law was developed by the international community, with a view to searching a common notion at the international level by comparing theory and practice within the main international organisations such as the UN, OECD and the Council of Europe. Specific mention is made of the EU experience, whose configuration as a Community based on the rule of law is often debated, starting from the case law of the European Court of Justice. The second chapter deals with the conditionality policy and focuses on the development and scope of democratic conditionality according to the dominant approach of the doctrine. First, the birth of conditionality is analysed from an economic point of view, especially within international financial organisations and the different types of conditionality recreated in the scientific sector. Then an analysis is provided about the birth of democratic conditionality in the EC – in relation to its external relations – firstly as a mere political exercise to be then turned into a standardised system of clauses. Specific reference is made to the main scope of conditionality, that is to say enlargement policy and the development of the Copenhagen criteria. The third chapter provides further details about the legal questions connected to the use of democratic clauses: on the one hand, the power of the EC to include human rights clauses in international agreements, on the other, the variety and overlapping in the use of the legal basis. The chapter ends with an analysis of the measures of suspension of agreements with third countries in those rare but significant cases in which the suspension clause, included in the Lomè Convention first and in the Cotonou Agreement then, is applied. The last chapter is devoted to the analysis of democratic clauses in unilateral acts adopted by the European Union which affect third countries. The examination of this practice and the comparison with the approach analysed in the previous chapter entails a major theoretical question. It is the clear-cut distinction between conditionality and international sanction. This distinction is to be taken into account when considering the premises and consequences, in terms of legal relations, which are generated when democratic clauses are not complied with. The chapter ends with a brief analysis of what, according to the reconstruction suggested, can be rightly labelled as real democratic conditionality, that is to say the system of incentives, positive measures developed within the community GSP. The dissertation ends with a few general considerations about the difficulties experienced by the EU in promoting the rule of law. The contradictory aspects of the EU external actions are manifold, as well as its difficulties in choosing the most appropriate measures to be taken which, however, reflect all the repercussions and tension resulting from the balance of power within the international community. The thesis argues that it is difficult to grant full credibility to an entity like the EU which, although it proclaims itself as the guardian and promoter of the rule of law, in practice, is too often biased in managing its relations with third countries. However, she adds, we must acknowledge that the EU is committed and constantly strives towards identifying new spaces and strategies of action.
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[EN]We present a new strategy for constructing tensor product spline spaces over quadtree and octree T-meshes. The proposed technique includes some simple rules for inferring local knot vectors to define spline blending functions. These rules allow to obtain for a given T-mesh a set of cubic spline functions that span a space with nice properties: it can reproduce cubic polynomials, the functions are C2-continuous, linearly independent, and spaces spanned by nested T-meshes are also nested. In order to span spaces with these properties applying the proposed rules, the T-mesh should fulfill the only requirement of being a 0-balanced quadtree or octree. ..
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[EN]We present a new strategy for constructing spline spaces over hierarchical T-meshes with quad- and octree subdivision scheme. The proposed technique includes some simple rules for inferring local knot vectors to define C 2 -continuous cubic tensor product spline blending functions. Our conjecture is that these rules allow to obtain, for a given T-mesh, a set of linearly independent spline functions with the property that spaces spanned by nested T-meshes are also nested, and therefore, the functions can reproduce cubic polynomials. In order to span spaces with these properties applying the proposed rules, the T-mesh should fulfill the only requirement of being a 0- balanced mesh...
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[EN]We present a new strategy for constructing tensor product spline spaces over quadtree and octree T-meshes. The proposed technique includes some simple rules for inferring local knot vectors to define spline blending functions. These rules allow to obtain for a given T-mesh a set of cubic spline functions that span a space with nice properties: it can reproduce cubic polynomials, the functions are C2-continuous, linearly independent, and spaces spanned by nested T-meshes are also nested. In order to span spaces with these properties applying the proposed rules, the T-mesh should fulfill the only requirement of being a 0-balanced quadtree or octree. ..
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The rational construction of the house. The writings and projects of Giuseppe Pagano Description, themes and research objectives The research aims at analysing the architecture of Giuseppe Pagano, which focuses on the theme of dwelling, through the reading of 3 of his house projects. On the one hand, these projects represent “minor” works not thoroughly known by Pagano’s contemporary critics; on the other they emphasise a particular methodological approach, which serves the author to explore a theme closely linked to his theoretical thought. The house project is a key to Pagano’s research, given its ties to the socio-cultural and political conditions in which the architect was working, so that it becomes a mirror of one of his specific and theoretical path, always in a state of becoming. Pagano understands architecture as a “servant of the human being”, subject to a “utilitarian slavery” since it is a clear, essential and “modest” answer to specific human needs, free from aprioristic aesthetic and formal choices. It is a rational architecture in sensu stricto; it constitutes a perfect synthesis between cause and effect and between function and form. The house needs to accommodate these principles because it is closely intertwined with human needs and intimately linked to a specific place, climatic conditions and technical and economical possibilities. Besides, differently from his public and common masterpieces such as the Palazzo Gualino, the Istituto di Fisica and the Università Commerciale Bocconi, the house projects are representative of a precise project will, which is expressed in a more authentic way, partially freed from political influences and dogmatic preoccupations and, therefore, far from the attempt to research a specific expressive language. I believe that the house project better represents that “ingenuity”, freshness and “sincerity” that Pagano identifies with the minor architecture, thereby revealing a more authentic expression of his understanding of a project. Therefore, the thesis, by tracing the theoretical research of Pagano through the analysis of some of his designed and built works, attempts to identify a specific methodological approach to Pagano’s project, which, developed through time, achieves a certain clarity in the 1930s. In fact, this methodological approach becomes more evident in his last projects, mainly regarding the house and the urban space. These reflect the attempt to respond to the new social needs and, at the same time, they also are an expression of a freer idea of built architecture, closely linked with the place and with the human being who dwells it. The three chosen projects (Villa Colli, La Casa a struttura d’acciaio and Villa Caraccio) make Pagano facing different places, different customers and different economic and technical conditions, which, given the author’s biography, correspond to important historical and political conditions. This is the reason why the projects become apparently distant works, both linguistically and conceptually, to the point that one can define them as ”eclectic”. However, I argue that this eclecticism is actually an added value to the architectural work of Pagano, steaming from the use of a method which, having as a basis the postulate of a rational architecture as essence and logic of building, finds specific variations depending on the multiple variables to be addressed by the project. This is the methodological heritage that Pagano learns from the tradition, especially that of the rural residential architecture, defined by Pagano as a “dictionary of the building logic of man”, as an “a-stylistic background”. For Pagano this traditional architecture is a clear expression of the relationships between a theme and its development, an architectural “fact” that is resolved with purely technical and utilitarian aims and with a spontaneous development far from any aprioristic theoretical principle. Architecture, therefore, cannot be an invention for Pagano and the personal contribution of each architect has to consider his/her close relationship with the specific historical context, place and new building methods. These are basic principles in the methodological approach that drives a great deal of his research and that also permits his thought to be modern. I argue that both ongoing and new collaborations with younger protagonists of the culture and architecture of the period are significant for the development of his methodology. These encounters represent the will to spread his own understanding of the “new architecture” as well as a way of self-renewal by confronting the self with new themes and realities and by learning from his collaborators. Thesis’ outline The thesis is divided in two principal parts, each articulated in four chapters attempting to offer a new reading of the theory and work of Pagano by emphasising the central themes of the research. The first chapter is an introduction to the thesis and to the theme of the rational house, as understood and developed in its typological and technical aspects by Pagano and by other protagonists of the Italian rationalism of the 1930s. Here the attention is on two different aspects defining, according to Pagano, the house project: on the one hand, the typological renewal, aimed at defining a “standard form” as a clear and essential answer to certain needs and variables of the project leading to different formal expressions. On the other, it focuses on the building, understood as a technique to “produce” architecture, where new technologies and new materials are not merely tools but also essential elements of the architectural work. In this way the villa becomes different from the theme of the common house or from that of the minimalist house, by using rules in the choice of material and in the techniques that are every time different depending on the theme under exploration and on the contingency of place. It is also visible the rigorous rationalism that distinguishes the author's appropriation of certain themes of rural architecture. The pages of “Casabella” and the events of the contemporary Triennali form the preliminary material for the writing of this chapter given that they are primary sources to individuate projects and writings produced by Pagano and contemporary architects on this theme. These writings and projects, when compared, reconstruct the evolution of the idea of the rational house and, specifically, of the personal research of Pagano. The second part regards the reading of three of Pagano’s projects of houses as a built verification of his theories. This section constitutes the central part of the thesis since it is aimed at detecting a specific methodological approach showing a theoretical and ideological evolution expressed in the vast edited literature. The three projects that have been chosen explore the theme of the house, looking at various research themes that the author proposes and that find continuity in the affirmation of a specific rationalism, focussed on concepts such as essentiality, utility, functionality and building honesty. These concepts guide the thought and the activities of Pagano, also reflecting a social and cultural period. The projects span from the theme of the villa moderna, Villa Colli, which, inspired by the architecture of North Europe, anticipates a specific rationalism of Pagano based on rigour, simplicity and essentiality, to the theme of the common house, Casa a struttura d’acciaio, la casa del domani, which ponders on the definition of new living spaces and, moreover, on new concepts of standardisation, economical efficiency and new materials responding to the changing needs of the modern society. Finally, the third project returns to the theme of the, Villa Caraccio, revisiting it with new perspectives. These perspectives find in the solution of the open plant, in the openness to nature and landscape and in the revisiting of materials and local building systems that idea of the freed house, which express clearly a new theoretical thought. Methodology It needs to be noted that due to the lack of an official Archive of Pagano’s work, the analysis of his work has been difficult and this explains the necessity to read the articles and the drawings published in the pages of «Casabella» and «Domus». As for the projects of Villa Colli and Casa a struttura d’acciaio, parts of the original drawings have been consulted. These drawings are not published and are kept in private archives of the collaborators of Pagano. The consultation of these documents has permitted the analysis of the cited works, which have been subject to a more complete reading following the different proposed solutions, which have permitted to understand the project path. The projects are analysed thought the method of comparison and critical reading which, specifically, means graphical elaborations and analytical schemes, mostly reconstructed on the basis of original projects but, where possible, also on a photographic investigation. The focus is on the project theme which, beginning with a specific living (dwelling) typology, finds variations because of the historico-political context in which Pagano is embedded and which partially shapes his research and theoretical thought, then translated in the built work. The analysis of the work follows, beginning, where possible, from a reconstruction of the evolution of the project as elaborated on the basis of the original documents and ending on an analysis of the constructive principles and composition. This second phase employs a methodology proposed by Pagano in his article Piante di ville, which, as expected, focuses on the plant as essential tool to identify the “true practical and poetic qualities of the construction”(Pagano, «Costruzioni-Casabella», 1940, p. 2). The reading of the project is integrated with the constructive analyses related to the technical aspects of the house which, in the case of Casa a struttura d’acciaio, play an important role in the project, while in Villa Colli and in Villa Caraccio are principally linked to the choice of materials for the construction of the different architectural elements. These are nonetheless key factors in the composition of the work. Future work could extend this reading to other house projects to deepen the research that could be completed with the consultation of Archival materials, which are missing at present. Finally, in the appendix I present a critical selection of the Pagano’s writings, which recall the themes discussed and embodied by the three projects. The texts have been selected among the articles published in Casabella and in other journals, completing the reading of the project work which cannot be detached from his theoretical thought. Moving from theory to project, we follow a path that brings us to define and deepen the central theme of the thesis: rational building as the principal feature of the architectural research of Pagano, which is paraphrased in multiple ways in his designed and built works.
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Clusters have increasingly become an essential part of policy discourses at all levels, EU, national, regional, dealing with regional development, competitiveness, innovation, entrepreneurship, SMEs. These impressive efforts in promoting the concept of clusters on the policy-making arena have been accompanied by much less academic and scientific research work investigating the actual economic performance of firms in clusters, the design and execution of cluster policies and going beyond singular case studies to a more methodologically integrated and comparative approach to the study of clusters and their real-world impact. The theoretical background is far from being consolidated and there is a variety of methodologies and approaches for studying and interpreting this phenomenon while at the same time little comparability among studies on actual cluster performances. The conceptual framework of clustering suggests that they affect performance but theory makes little prediction as to the ultimate distribution of the value being created by clusters. This thesis takes the case of Eastern European countries for two reasons. One is that clusters, as coopetitive environments, are a new phenomenon as the previous centrally-based system did not allow for such types of firm organizations. The other is that, as new EU member states, they have been subject to the increased popularization of the cluster policy approach by the European Commission, especially in the framework of the National Reform Programmes related to the Lisbon objectives. The originality of the work lays in the fact that starting from an overview of theoretical contributions on clustering, it offers a comparative empirical study of clusters in transition countries. There have been very few examples in the literature that attempt to examine cluster performance in a comparative cross-country perspective. It adds to this an analysis of cluster policies and their implementation or lack of such as a way to analyse the way the cluster concept has been introduced to transition economies. Our findings show that the implementation of cluster policies does vary across countries with some countries which have embraced it more than others. The specific modes of implementation, however, are very similar, based mostly on soft measures such as funding for cluster initiatives, usually directed towards the creation of cluster management structures or cluster facilitators. They are essentially founded on a common assumption that the added values of clusters is in the creation of linkages among firms, human capital, skills and knowledge at the local level, most often perceived as the regional level. Often times geographical proximity is not a necessary element in the application process and cluster application are very similar to network membership. Cluster mapping is rarely a factor in the selection of cluster initiatives for funding and the relative question about critical mass and expected outcomes is not considered. In fact, monitoring and evaluation are not elements of the cluster policy cycle which have received a lot of attention. Bulgaria and the Czech Republic are the countries which have implemented cluster policies most decisively, Hungary and Poland have made significant efforts, while Slovakia and Romania have only sporadically and not systematically used cluster initiatives. When examining whether, in fact, firms located within regional clusters perform better and are more efficient than similar firms outside clusters, we do find positive results across countries and across sectors. The only country with negative impact from being located in a cluster is the Czech Republic.
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Since the birth of the European Union on 1957, the development of a single market through the integration of national freight transport networks has been one of the most important points in the European Union agenda. Increasingly congested motorways, rising oil prices and concerns about environment and climate change require the optimization of transport systems and transport processes. The best solution should be the intermodal transport, in which the most efficient transport options are used for the different legs of transport. This thesis examines the problem of defining innovative strategies and procedures for the sustainable development of intermodal freight transport in Europe. In particular, the role of maritime transport and railway transport in the intermodal chain are examined in depth, as these modes are recognized to be environmentally friendly and energy efficient. Maritime transport is the only mode that has kept pace with the fast growth in road transport, but it is necessary to promote the full exploitation of it by involving short sea shipping as an integrated service in the intermodal door-to-door supply chain and by improving port accessibility. The role of Motorways of the Sea services as part of the Trans-European Transport Network is is taken into account: a picture of the European policy and a state of the art of the Italian Motorways of the Sea system are reported. Afterwards, the focus shifts from line to node problems: the role of intermodal railway terminals in the transport chain is discussed. In particular, the last mile process is taken into account, as it is crucial in order to exploit the full capacity of an intermodal terminal. The difference between the present last mile planning models of Bologna Interporto and Verona Quadrante Europa is described and discussed. Finally, a new approach to railway intermodal terminal planning and management is introduced, by describing the case of "Terminal Gate" at Verona Quadrante Europa. Some proposals to favour the integrate management of "Terminal Gate" and the allocation of its capacity are drawn up.
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The purpose of this Thesis is to develop a robust and powerful method to classify galaxies from large surveys, in order to establish and confirm the connections between the principal observational parameters of the galaxies (spectral features, colours, morphological indices), and help unveil the evolution of these parameters from $z \sim 1$ to the local Universe. Within the framework of zCOSMOS-bright survey, and making use of its large database of objects ($\sim 10\,000$ galaxies in the redshift range $0 < z \lesssim 1.2$) and its great reliability in redshift and spectral properties determinations, first we adopt and extend the \emph{classification cube method}, as developed by Mignoli et al. (2009), to exploit the bimodal properties of galaxies (spectral, photometric and morphologic) separately, and then combining together these three subclassifications. We use this classification method as a test for a newly devised statistical classification, based on Principal Component Analysis and Unsupervised Fuzzy Partition clustering method (PCA+UFP), which is able to define the galaxy population exploiting their natural global bimodality, considering simultaneously up to 8 different properties. The PCA+UFP analysis is a very powerful and robust tool to probe the nature and the evolution of galaxies in a survey. It allows to define with less uncertainties the classification of galaxies, adding the flexibility to be adapted to different parameters: being a fuzzy classification it avoids the problems due to a hard classification, such as the classification cube presented in the first part of the article. The PCA+UFP method can be easily applied to different datasets: it does not rely on the nature of the data and for this reason it can be successfully employed with others observables (magnitudes, colours) or derived properties (masses, luminosities, SFRs, etc.). The agreement between the two classification cluster definitions is very high. ``Early'' and ``late'' type galaxies are well defined by the spectral, photometric and morphological properties, both considering them in a separate way and then combining the classifications (classification cube) and treating them as a whole (PCA+UFP cluster analysis). Differences arise in the definition of outliers: the classification cube is much more sensitive to single measurement errors or misclassifications in one property than the PCA+UFP cluster analysis, in which errors are ``averaged out'' during the process. This method allowed us to behold the \emph{downsizing} effect taking place in the PC spaces: the migration between the blue cloud towards the red clump happens at higher redshifts for galaxies of larger mass. The determination of $M_{\mathrm{cross}}$ the transition mass is in significant agreement with others values in literature.
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Phylogeography is a recent field of biological research that links phylogenetics to biogeography through deciphering the imprint that evolutionary history has left on the genetic structure of extant populations. During the cold phases of the successive ice ages, which drastically shaped species’ distributions since the Pliocene, populations of numerous species were isolated in refugia where many of them evolved into different genetic lineages. My dissertation deals with the phylogeography of the Woodland Ringlet (Erebia medusa [Denis and Schiffermüller] 1775) in Central and Eastern Europe. This Palaearctic butterfly species is currently distributed from central France and south eastern Belgium over large parts of Central Europe and southern Siberia to the Pacific. It is absent from those parts of Europe with mediterranean, oceanic and boreal climates. It was supposed to be a Siberian faunal element with a rather homogeneous population structure in Central Europe due to its postglacial expansion out of a single eastern refugium. An already existing evolutionary scenario for the Woodland Ringlet in Central and Eastern Europe is based on nuclear data (allozymes). To know if this is corroborated by organelle evolutionary history, I sequenced two mitochondrial markers (part of the cytochrome oxydase subunit one and the control region) for populations sampled over the same area. Phylogeography largely relies on the construction of networks of uniparentally inherited haplotypes that are compared to geographic haplotype distribution thanks to recent developed methods such as nested clade phylogeographic analysis (NCPA). Several ring-shaped ambiguities (loops) emerged from both haplotype networks in E. medusa. They can be attributed to recombination and homoplasy. Such loops usually avert the straightforward extraction of the phylogeographic signal contained in a gene tree. I developed several new approaches to extract phylogeographic information in the presence of loops, considering either homoplasy or recombination. This allowed me to deduce a consistent evolutionary history for the species from the mitochondrial data and also adds plausibility for the occurrence of recombination in E. medusa mitochondria. Despite the fact that the control region is assumed to have a lack of resolving power in other species, I found a considerable genetic variation of this marker in E. medusa which makes it a useful tool for phylogeographic studies. In combination with the allozyme data, the mitochondrial genome supports the following phylogeographic scenario for E. medusa in Europe: (i) a first vicariance, due to the onset of the Würm glaciation, led to the formation of several major lineages, and is mirrored in the NCPA by restricted gene flow, (ii) later on further vicariances led to the formation of two sub-lineages in the Western lineage and two sub-lineages in the Eastern lineage during the Last Glacial Maximum or Older Dryas; additionally the NCPA supports a restriction of gene flow with isolation by distance, (iii) finally, vicariance resulted in two secondary sub-lineages in the area of Germany and, maybe, to two other secondary sub-lineages in the Czech Republic. The last postglacial warming was accompanied by strong range expansions in most of the genetic lineages. The scenario expected for a presumably Siberian faunal element such as E. medusa is a continuous loss of genetic diversity during postglacial westward expansion. Hence, the pattern found in this thesis contradicts a typical Siberian origin of E. medusa. In contrast, it corroboratess the importance of multiple extra-Mediterranean refugia for European fauna as it was recently assumed for other continental species.
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The present thesis is a contribution to the multi-variable theory of Bergman and Hardy Toeplitz operators on spaces of holomorphic functions over finite and infinite dimensional domains. In particular, we focus on certain spectral invariant Frechet operator algebras F closely related to the local symbol behavior of Toeplitz operators in F. We summarize results due to B. Gramsch et.al. on the construction of Psi_0- and Psi^*-algebras in operator algebras and corresponding scales of generalized Sobolev spaces using commutator methods, generalized Laplacians and strongly continuous group actions. In the case of the Segal-Bargmann space H^2(C^n,m) of Gaussian square integrable entire functions on C^n we determine a class of vector-fields Y(C^n) supported in complex cones K. Further, we require that for any finite subset V of Y(C^n) the Toeplitz projection P is a smooth element in the Psi_0-algebra constructed by commutator methods with respect to V. As a result we obtain Psi_0- and Psi^*-operator algebras F localized in cones K. It is an immediate consequence that F contains all Toeplitz operators T_f with a symbol f of certain regularity in an open neighborhood of K. There is a natural unitary group action on H^2(C^n,m) which is induced by weighted shifts and unitary groups on C^n. We examine the corresponding Psi^*-algebra A of smooth elements in Toeplitz-C^*-algebras. Among other results sufficient conditions on the symbol f for T_f to belong to A are given in terms of estimates on its Berezin-transform. Local aspects of the Szegö projection P_s on the Heisenbeg group and the corresponding Toeplitz operators T_f with symbol f are studied. In this connection we apply a result due to Nagel and Stein which states that for any strictly pseudo-convex domain U the projection P_s is a pseudodifferential operator of exotic type (1/2, 1/2). The second part of this thesis is devoted to the infinite dimensional theory of Bergman and Hardy spaces and the corresponding Toeplitz operators. We give a new proof of a result observed by Boland and Waelbroeck. Namely, that the space of all holomorphic functions H(U) on an open subset U of a DFN-space (dual Frechet nuclear space) is a FN-space (Frechet nuclear space) equipped with the compact open topology. Using the nuclearity of H(U) we obtain Cauchy-Weil-type integral formulas for closed subalgebras A in H_b(U), the space of all bounded holomorphic functions on U, where A separates points. Further, we prove the existence of Hardy spaces of holomorphic functions on U corresponding to the abstract Shilov boundary S_A of A and with respect to a suitable boundary measure on S_A. Finally, for a domain U in a DFN-space or a polish spaces we consider the symmetrizations m_s of measures m on U by suitable representations of a group G in the group of homeomorphisms on U. In particular,in the case where m leads to Bergman spaces of holomorphic functions on U, the group G is compact and the representation is continuous we show that m_s defines a Bergman space of holomorphic functions on U as well. This leads to unitary group representations of G on L^p- and Bergman spaces inducing operator algebras of smooth elements related to the symmetries of U.
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In the marine Jurassic deposits of Europe, a group of marine crocodilians, the Thalattosuchia, belongs to the frequently found reptiles. Thalattosuchia are widely spread in Central Europe from the Jurassic to Lower Cretaceous, and some taxa are also distributed worldwide. The task of the work was to examine all taxa known from the Liassic of Europe. The most frequently known taxa Steneosaurus bollensis and Pelagosaurus typus are anatomically revised. New discoveries at the skull of Pelagosaurus typus e.g., the fact of a partly paired frontal are described by means of computed tomography investigations. In addition, juvenile specimens of this taxon are studied in detail for the first time. The rarely occurring taxon Platysuchus multiscrobiculatus is anatomically described in detail for the first time. It shows both in the skull and in the postcranial material morphological differences to Steneosaurus bollensis and Pelagosaurus typus. Thus Pl. multiscrobiculatus possesses, e.g., an ilium with a deeper acetabulum and a femur with a distinctly flexed femoral head. A juvenile specimen of Pl. multiscrobiculatus is now discovered and is described in parts for the first time, too. Furthermore, Steneosaurus gracilirostris and Steneosaurus brevior known from Lower Jurassic deposits of England are examined and in parts revised. In this work, Steneosaurs brevior is discovered with one specimen from the Upper Liassic of Holzmaden, Germany for the first time, and provides new evidence for the palaeobiogeographical distribution of the taxon. Because of the high number of investigated specimens, it is possible to study ontogenetic development from juvenile to adult stage in Steneosaurus bollensis, Pelagosaurus typus, and Platysuchus multiscrobiculatus. Biometric data are collected from thalattosuchians and extant crocodilians (e.g. Gavialis gangeticus) to investigate intraspecific variation, ontogenetic development, and taxa differentiation. The skulls of Platysuchus multiscrobiculatus and Steneosaurus bollensis are reconstructed three-dimensionally as wax models. The skull reconstructions form the basis of the jaw muscle restoration of Steneosaurus bollensis in connection with comparative studies at extant crocodilians. By means of functional morphologic analysis of the jaw musculature, the dentition, and the locomotor system of S. bollensis, possible conclusions are drawn for the prey options and the hunting behaviour. To clarify the relationships within the Thalattosuchia, a computer-based cladistic phylogenetic in-group analyse of 25 Thalattosuchia taxa is performed. For the analysis, following Thalattosuchia taxa are studied likewise at original material for comparisons: Metriorhynchus superciliosus, Metriorhynchus hastifer, Metriorhynchus leedsi, Geosaurus gracilis, Geosaurus giganteus, Teleidosaurus calvadosi, Teleidosaurus gaudryi, Teleosaurus cadomensis, Teleosaurus geoffroyi, Steneosaurus priscus, Steneosaurus edwardsi, Steneosaurus heberti, Steneosaurus leedsi, Steneosaurus boutilieri, Steneosaurus megarhinus, Steneosaurus obtusidens, and Machimosaurus hugii. The phylogenetic in-group analyse based on 115 characters, reveals a sister-group relationship of the monophyletic Teleosauridae and monophyletic Metriorhynchidae. Within the groups, some taxa are probably paraphyletic. The taxon Pelagosaurus typus is nested inside the Teleosauridae and not outside or within the Metriorhynchidae, as many authors suggested it so far. Based on these results, a tentative palaeobiogeographical-evolutionary scenario is developed.