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Un episodio en la vida del pintor viajero : mala literatura y escritura fulminante en Cesar Aira
(2011)
The sixth volume of the DIGAREC Series holds the contributions to the DIGAREC Keynote-Lectures given at the University of Potsdam in the winter semester 2009/10. With contributions by Mark J.P. Wolf (Concordia University Wisconsin), Espen Aarseth (Center for Computer Games Research, IT University of Copenhagen), Katie Salen (Parsons New School of Design, New York), Laura Ermi and Frans Mäyrä (University of Tampere), and Lev Manovich (University of Southern California, San Diego).
Introduction
(2011)
Simultaneous limitation of plant growth by two or more nutrients is increasingly acknowledged as a common phenomenon in nature, but its cellular mechanisms are far from understood. We investigated the uptake kinetics of CO(2) and phosphorus of the algae Chlamydomonas acidophila in response to growth at limiting conditions of CO(2) and phosphorus. In addition, we fitted the data to four different Monod-type models: one assuming Liebigs Law of the minimum, one assuming that the affinity for the uptake of one nutrient is not influenced by the supply of the other (independent colimitation) and two where the uptake affinity for one nutrient depends on the supply of the other (dependent colimitation). In addition we asked whether the physiological response under colimitation differs from that under single nutrient limitation. We found no negative correlation between the affinities for uptake of the two nutrients, thereby rejecting a dependent colimitation. Kinetic data were supported by a better model fit assuming independent uptake of colimiting nutrients than when assuming Liebigs Law of the minimum or a dependent colimitation. Results show that cell nutrient homeostasis regulated nutrient acquisition which resulted in a trade-off in the maximum uptake rates of CO(2) and phosphorus, possibly driven by space limitation on the cell membrane for porters for the different nutrients. Hence, the response to colimitation deviated from that to a single nutrient limitation. In conclusion, responses to single nutrient limitation cannot be extrapolated to situations where multiple nutrients are limiting, which calls for colimitation experiments and models to properly predict growth responses to a changing natural environment. These deviations from single nutrient limitation response under colimiting conditions and independent colimitation may also hold for other nutrients in algae and in higher plants.
1. Herbivores show stronger control of element homoeostasis than primary producers, which can lead to constraints in carbon and nutrient transfer efficiencies from plants to animals. Insufficient dietary phosphorus (P) availability can cause reduced body P contents along with lower growth rates of animals, leading to a positive relationship between growth and body P.
2. We examined how a second limiting food component in combination with dietary P limitation influences growth and P homoeostasis of a herbivore and how this colimitation influences the hypothesized positive correlation between body P content and growth rates. Therefore, we investigated the responses in somatic growth and P stoichiometry of Daphnia magna raised on a range of diets with different amounts of P and the sterol cholesterol.
3. Somatic growth rates of D. magna increased asymptotically with increasing P as well as with increasing cholesterol availability. The body P content increased with increasing dietary P and stabilized at high dietary P availability. The observed plasticity in D. magna's P stoichiometry became stronger with increasing cholesterol availability, i.e. with decreasing colimitation by cholesterol.
4. At P-limiting conditions, the positive correlation between body P content and growth rate, as predicted by the growth rate hypothesis (GRH) applied to the within-species level, declined with increasing cholesterol limitation and disappeared entirely when cholesterol was not supplied. Thus, even when Daphnia shows no growth response owing to strong limitation by the colimiting nutrient, the body P content may vary substantially, calling into question the unconditional use of herbivores' P content as predictor of a potential P limitation in nature.
5. The observed interaction between dietary P and cholesterol on Daphnia's growth and stoichiometry can be used as a conceptual framework of how colimiting essential nutrients affect herbivore homoeostasis, and provide further insights into the applicability of the GRH within a consumer species.
The CO2 acquisition was analyzed in Chlamydomonas acidophila at pH 2.4 in a range of medium P and Fe concentrations and at high and low CO2 condition. The inorganic carbon concentrating factor (CCF) was related to cellular P quota (Q(p)), maximum CO2-uptake rate by photosynthesis (V-max; O-2), half saturation constant for CO2 uptake (K-0.5), and medium Fe concentration. There was no effect of the medium Fe concentration on the CCF. The CCF increased with increasing Q(p) in both high and low CO2 grown algae, but maximum Q(p) was 6-fold higher in the low CO2 cells. In high CO2 conditions, the CCF was low, ranging between 0.8 and 3.5. High CCF values up to 9.1 were only observed in CO2-limited cells, but P- and CO2-colimited cells had a low CCF. High CCF did not relate with a low K-0.5 as all CO2-limited cells had a low K-0.5 (<4 mu M CO2). High Ci-pools in cells with high Qp suggested the presence of an active CO2-uptake mechanism. The CCF also increased with increasing V-max; O-2 which reflect an adaptation to the nutrient in highest demand (CO2) under balanced growth conditions. It is proposed that the size of the CCF in C. acidophila is more strongly related to porter density for CO2 uptake (reflected in V-max; O-2) and less- to high-affinity CO2 uptake (low K-0.5) at balanced growth. In addition, high CCF can only be realized with high Q(p).
The extremophilic microalga Chlamydomonas acidophila inhabits very acidic waters (pH 2-3.5), where its growth is often limited by phosphorus (P) or colimited by P and inorganic carbon (CO(2)). Because this alga is a major food source for predators in acidic habitats, we studied its fatty acid content, which reflects their quality as food, grown under a combination of P-limited and different carbon conditions (either mixotrophically with light + glucose or at high or low CO(2), both without glucose). The fatty acid composition largely depended on the cellular P content: stringent P-limited cells had a higher total fatty acid concentration and had a lower percentage of polyunsaturated fatty acids. An additional limitation for CO(2) inhibited this decrease, especially reflected in enhanced concentrations of 18:3(9,12,15) and 16:4(3,7,10,13), resulting in cells relatively rich in polyunsaturated fatty acids under colimiting growth conditions. The percentage of polyunsaturated to total fatty acid content was positively related with maximum photosynthesis under all conditions applied. The two factors, P and CO(2), thus interact in their effect on the fatty acid composition in C. acidophila, and colimited cells P-limited algae can be considered a superior food source for herbivores because of the high total fatty acid content and relative richness in polyunsaturated fatty acids.
We present data on eicosapentaenoic acid (EPA)-limited growth responses of Daphnia magna under different temperatures and different dietary cholesterol availabilities to assess how EPA growth saturation thresholds depend on changing environmental conditions. D. magna was raised on gradients of dietary EPA at 15 degrees C and 20 degrees C with high cholesterol supply and at 20 degrees C with low and high cholesterol supply in laboratory experiments. A new method was applied to estimate EPA growth saturation thresholds on the basis of fitted saturation curves using bootstrapped data. The EPA threshold at which 75% and 90% of maximum growth was reached ranged from 0.7 to 1.6 mu g EPA (mg dietary C)(-1) and 2.0 to 4.9 mu g EPA (mg dietary C)(-1), respectively. Previously reported EPA concentrations in natural seston of many different lakes suggest that the thresholds measured here indicate a frequent potential for at least moderate EPA limitation in nature. Furthermore, the calculated EPA thresholds were higher in treatments of low compared with high temperature and higher in treatments of low compared with high cholesterol availability. The EPA-dependent growth responses were more strongly affected by temperature than by cholesterol availability. Our results suggest that EPA growth saturation thresholds for a particular Daphnia species probably vary in nature under different environmental conditions.
Philosophien neuer Musik
(2011)
The problem of an ensemble Kalman filter when only partial observations are available is considered. In particular, the situation is investigated where the observational space consists of variables that are directly observable with known observational error, and of variables of which only their climatic variance and mean are given. To limit the variance of the latter poorly resolved variables a variance-limiting Kalman filter (VLKF) is derived in a variational setting. The VLKF for a simple linear toy model is analyzed and its range of optimal performance is determined. The VLKF is explored in an ensemble transform setting for the Lorenz-96 system, and it is shown that incorporating the information of the variance of some unobservable variables can improve the skill and also increase the stability of the data assimilation procedure.
Basiswissen BWL – prägnant und verständlich vermittelt. Das Lehrbuch vermittelt Wirtschaftswissenschaftlern, angehenden Wirtschaftsingenieuren und -informatikern sowie Nebenfachstudierenden aus dem technischen Bereich die wichtigsten Grundlagen der BWL. Die 6. Auflage wurde umfassend überarbeitet, an die aktuelle Gesetzeslage angepasst und inhaltlich erweitert. Lernziele, Beispiele, Kontrollfragen und Aufgaben inklusive Lösungen erleichtern das selbstständige Lernen. Das optimierte Layout sorgt für mehr Übersichtlichkeit.
Die jüngsten Unruhen in der arabischen Welt haben eine jahrzehntelange Periode politischer Stagnation beendet. Bei der anstehenden staatlichen Reorganisation werden sowohl Militärs als auch islamistische Bewegungen eine wichtige Rolle spielen. Infolge der Umstürze verschieben sich nicht nur regionale Kräfteverhältnisse, sondern auch die Einflussmöglichkeiten der Weltmächte im Nahen Osten. Die USA und der Westen insgesamt verlieren an Relevanz und müssen ihre Nahostpolitik auf ein neues Fundament stellen. Das machtpolitische Vakuum in dem energie- und sicherheitspolitisch bedeutsamen Raum aber werden neue Akteure wie China und die Türkei füllen.
In Stanley Kubricks Film von 1964 lernten wir, die Bombe zu lieben. Heute, 66 Jahre nach der ersten nuklearen Detonation, haben wir uns mit dem Wissen um ihre absolute Zerstörungskraft arrangiert. In einer multipolaren Welt scheint die atomare Währung jedoch an Wert zu verlieren. Ist die Vision einer nuklearwaffenfreien Zukunft also nur ein Traum oder können wir lernen, auf die Bombe zu verzichten? Rolf Mützenich, MdB und außenpolitischer Sprecher der SPD-Bundestagsfraktion, hat sich dieser Frage angenommen.
Der Bürger entscheidet mit
(2011)
»Warum erregt der geplante Abriss eines Bahnhofs die Nation, während gegen das hundertfache Sterben von Bibliotheken immer nur ein paar Stimmen laut werden? Wo sind die Wutbürger, wenn man sie braucht?«, überlegte sich hierzulande Tilman Spreckelsen.1 Die Kernfrage lautet also: Stehen die Bürger eigentlich hinter der Bibliothek? Ob und wie die Bürgerschaft für ihre Öffentliche Bibliothek entscheidet, wenn sie entscheiden darf, wird im vorliegenden Aufsatz thematisiert. Ergebnisse von Bürgerbegehren und Bürgerentscheiden stehen dabei im Fokus, da bürgerschaftliches Engagement bei diesen Mitwirkungsinstrumenten besonders gefragt ist und es gleichzeitig kommunalpolitische Folgen haben kann. Am Beispiel von Stuttgart 21 wird darüber hinaus der Fragestellung nachgegangen, wie sich eine Öffentliche Bibliothek zu Sachverhalten positioniert, die (nicht nur) kommunalpolitisch brisant sind.
Was machen Verwaltungsmanager wirklich? : Explorative Ergebnisse eines Lehrforschungsprojekts
(2011)
Dieses Sonderheft der Schriftenreihe des Lehrstuhls für Public Management präsentiert ausgewählte Ergebnisse eines Lehrforschungsprojektes. Dabei wurde in Anlehnung an Mintzbergs Managementforschung die Frage gestellt, wie Führungskräfte in der Verwaltung tatsächlich ihre Organisationen steuern. Das Sonderheft enthält die explorativen Befunde aus drei empirischen Studien, die von Teilnehmern und Teilnehmerinnen des Seminars durchgeführt wurden.
Der E-Government-Fortschritt wird nach wie vor durch redundante Entwicklungsaktivitäten und isolierte, wenig interoperable Lösungen gehemmt. Die Herausforderung liegt weniger in der Entwicklung und Einführung leistungsstarker Informationssysteme, sondern in der Verbreitung bestehender Lösungen. Die Arbeit identifiziert mögliche Strategien für den Transfer von E-Government-Lösungen zwischen Verwaltungen gleicher wie auch verschiedener föderaler Ebene. Es werden Konzepte zur Diffusion von Innovationen, zum Technologie- wie auch Politiktransfer herangezogen. Weiter werden drei umfangreiche Fallstudien vorgestellt. Sie führen zu transferhemmenden wie auch fördernden Faktoren und somit zu Gestaltungsoptionen für erfolgreiche Transferprozesse unter den vielfältigen Rahmenbedingungen im öffentlichen Sektor.
Aus dem Inhalt: - Kinderrechte ohne Vorbehalt – Die Folgen der unmittelbaren Anwendbarkeit des - Kindeswohlvorrangs nach der UN-Kinderrechtskonvention - Wohin steuert der UN-Menschenrechtsrat? Stand und Perspektiven des Review-Prozesses - Das erste Urteil des Afrikanischen Gerichtshofs für Menschen- und Völkerrechte
The present thesis was born and evolved within the RAdial Velocity Experiment (RAVE) with the goal of measuring chemical abundances from the RAVE spectra and exploit them to investigate the chemical gradients along the plane of the Galaxy to provide constraints on possible Galactic formation scenarios. RAVE is a large spectroscopic survey which aims to observe spectroscopically ~10^6 stars by the end of 2012 and measures their radial velocities, atmospheric parameters and chemical abundances. The project makes use of the UK Schmidt telescope at Australian Astronomical Observatory (AAO) in Siding Spring, Australia, equipped with the multiobject spectrograph 6dF. To date, RAVE collected and measured more than 450,000 spectra. The precision of the chemical abundance estimations depends on the reliability of the atomic and atmosphere parameters adopted (in particular the oscillator strengths of the absorption lines and the effective temperature, gravity, and metallicity of the stars measured). Therefore we first identified 604 absorption lines in the RAVE wavelength range and refined their oscillator strengths with an inverse spectral analysis. Then, we improved the RAVE stellar parameters by modifying the RAVE pipeline and the spectral library the pipeline rely on. The modifications removed some systematic errors in stellar parameters discovered during this work. To obtain chemical abundances, we developed two different processing pipelines. Both of them perform chemical abundances measurements by assuming stellar atmospheres in Local Thermodynamic Equilibrium (LTE). The first one determines elements abundances from equivalent widths of absorption lines. Since this pipeline showed poor sensibility on abundances relative to iron, it has been superseded. The second one exploits the chi^2 minimization technique between observed and model spectra. Thanks to its precision, it has been adopted for the creation of the RAVE chemical catalogue. This pipeline provides abundances with uncertains of about ~0.2dex for spectra with signal-to-noise ratio S/N>40 and ~0.3dex for spectra with 20>S/N>40. For this work, the pipeline measured chemical abundances up to 7 elements for 217,358 RAVE stars. With these data we investigated the chemical gradients along the Galactic radius of the Milky Way. We found that stars with low vertical velocities |W| (which stay close to the Galactic plane) show an iron abundance gradient in agreement with previous works (~-0.07$ dex kpc^-1) whereas stars with larger |W| which are able to reach larger heights above the Galactic plane, show progressively flatter gradients. The gradients of the other elements follow the same trend. This suggests that an efficient radial mixing acts in the Galaxy or that the thick disk formed from homogeneous interstellar matter. In particular, we found hundreds of stars which can be kinetically classified as thick disk stars exhibiting a chemical composition typical of the thin disk. A few stars of this kind have already been detected by other authors, and their origin is still not clear. One possibility is that they are thin disk stars kinematically heated, and then underwent an efficient radial mixing process which blurred (and so flattened) the gradient. Alternatively they may be a transition population" which represents an evolutionary bridge between thin and thick disk. Our analysis shows that the two explanations are not mutually exclusive. Future follow-up high resolution spectroscopic observations will clarify their role in the Galactic disk evolution.
Mit dem vorliegenden Band „Nach Bologna: Praktika im Studium – Pflicht oder Kür? Empirische Analysen und Empfehlungen für die Hochschulpraxis“ von Wilfried Schubarth, Karsten Speck und Andreas Seidel wird die Reihe „Potsdamer Beiträge zur Lehrevaluation“ unter neuem Titel und veränderter inhaltlicher Schwerpunktsetzung fortgeführt. Die Umbenennung in „Potsdamer Beiträge zur Hochschulforschung“ versteht sich als ein Schritt hin zu einer thematischen Öffnung der Reihe für die verschiedensten Felder der Hochschulforschung. Der vorliegende Band widmet sich einem der zentralen Reformziele von Bologna: der Frage des Praxis- und Berufsbezugs und dabei insbesondere den Praxisphasen im Studium. Mit der Bologna-Reform werden im bildungspolitischen Bereich sehr vielfältige strukturelle und inhaltliche Ziele verfolgt. Das Ziel dieses Bandes besteht deshalb darin, empirische Forschungen zu Praxisbezügen und Praxisphasen im Studium vorzustellen, diese in den Kontext aktueller Debatten um Studienqualität und Studienreform zu stellen sowie Folgerungen für die Gestaltung von Praxisphasen abzuleiten. Inhaltliche Schwerpunkte bilden das BMBF-Forschungsprojekt ProPrax und die Praxisphasen im Lehramtsstudium. Die Beiträge dieses Bandes gehen aus einem gleichnamigen Workshop hervor, der am 1. Oktober 2010 in Potsdam stattfand.
We define several notions of singular set for Type-I Ricci flows and show that they all coincide. In order to do this, we prove that blow-ups around singular points converge to nontrivial gradient shrinking solitons, thus extending work of Naber [15]. As a by-product we conclude that the volume of a finite-volume singular set vanishes at the singular time.
We also define a notion of density for Type-I Ricci flows and use it to prove a regularity theorem reminiscent of White's partial regularity result for mean curvature flow [22].
Top-Manager stehen seit einigen Jahren verstärkt im Visier der Medien. Durch die mediale Aufmerksamkeit erlangen sie einen Prominentenstatus, der in der angloamerikanischen Managementforschung zu schillernden Bezeichnungen wie Celebrity CEO oder Superstar CEO führt. Nadine Bültel widmet sich in ihrer Arbeit diesem neuartigen Star- Phänomen von Top-Managern und untersucht die Ursachen und Auswirkungen ihrer medialen Prominenz. Sie analysiert, wie Manager eine Starreputation aufbauen und welche Rolle die Medien hierbei spielen. Im Mittelpunkt steht dabei auch die Frage, ob und warum Starmanager eine höhere Vergütung erhalten als ihre weniger prominenten Kollegen.
In vorliegender Arbeit werden die Gefahren und Chancen des gemeinschaftlichen Zusammenlebens im Exil am Beispiel der ehemaligen Colonia Dignidad in Chile analysiert. Die Colonia Dignidad (dt.: Kolonie der Würde) wurde 1961 von Mitgliedern einer deutschen Sekte im Zentrum des Landes, ca. 400 km südlich von Santiago entfernt, gegründet. Nach außen präsentierte sich die Gemeinschaft als glückliche und zufriedene deutsche Enklave, die ihre heimatlichen Traditionen und Bräuche im Ausland weiterhin pflegt. Mit dem Ende der Militärdiktatur unter Augusto Pinochet 1990 und dem damit verbundenen Wegfall der politischen Rückendeckung der Gemeinschaft, begann die chilenische Justiz die schon länger bestehenden Vorwürfe gegen den damaligen Sektenführer Paul Schäfer, u. a. wegen Kindesmissbrauchs und Folter an chilenischen Oppositionellen während der Militärdiktatur, zu untersuchen. Dem chilenischen Haftbefehl acht Jahre später entzog sich Paul Schäfer durch seine Flucht nach Argentinien. Die zurückbleibenden Mitglieder der Colonia Dignidad waren aufgrund des einsetzenden Zerfalls der alten Gemeinschaftsordnung gezwungen, sich ein neues Gemeinschaftskonzept zu erarbeiten, eines, in dem die bisher so dominante Führerfigur fehlte.
Sowohl das Gemeinschaftsleben in der Colonia Dignidad zwischen 1961 und 1998 als auch das Zusammenleben in der heutigen Villa Baviera ab 1998 wird anhand der Theorien zur Gemeinschaftsforschung von Ferdinand Tönnies, Georg Vobruba, Zygmunt Baumann, Matthias Grundmann und Stephan Drucks analysiert. Im Findungsprozess eines neuen Gemeinschaftskonzeptes waren die Mitglieder der ehemaligen Colonia Dignidad gezwungen, sich mit der Vergangenheit auseinanderzusetzen. In diesem Zusammenhang wird der Frage nachgegangen, inwiefern eine Aufarbeitung der Vergangenheit (memoria) im kulturwissenschaftlichen und psychologischen Sinne stattfand bzw. stattfindet und wenn ja, wie sich diese gestaltete bzw. gestaltet. Hierzu wird untersucht, welche staatlichen Maßnahmen zur Unterstützung des Neuanfangs der Gemeinschaft getroffen wurden und welchen Erfolg diese Maßnahmen hatten. Basierend auf den daraus gewonnenen Resultaten und der aktuellen Selbstdarstellung der Villa Baviera in ihrer Webpräsenz, wird das neue Gemeinschaftskonzept der ehemaligen Colonia Dignidad auf die Chancen des Zusammenlebens hin analysiert. Weiterführend werden Konzepte zum kollektiven Gedächtnis untersucht, von dem „Familiengedächtnis“ auf ein „Gemeinschaftsgedächtnis“ übertragen und mit der Frage nach der konstruktiven memoria innerhalb der Villa Baviera verbunden. Abschließend wird der Frage nachgegangen, welche positiven Aspekte des Gemeinschaftslebens einer intentionalen Gemeinschaft auf das Gemeinschaftsleben der Villa Baviera übertragen werden könnten.
Der vorliegende Beitrag knüpft an die in Potsdam seit 2001 durchgeführte Langzeitstudie an und untersucht die aktuelle Situation auf dem formellen Beteiligungsmarkt in Deutschland nach dem Ausbruch der Finanzkrise. Neben den allgemeinen Gegebenheiten des Marktes werden vor allem die Finanzierungsbedingungen sowie das Investitionsverhalten einzelner Beteiligungsgesellschaften analysiert. In den Jahren 2008 - 2009 zeigt sich einerseits eine weitestgehend unveränderte Struktur der Refinanzierungsquellen. Privatpersonen und Banken sowie der öffentliche Sektor nehmen weiterhin einen hohen Stellenwert ein. Andererseits werden deutliche Veränderungen der strukturellen Merkmale, wie auch im Investitionsverhalten einzelner Beteiligungsgesellschaften deutlich. Besonders auffällig für die Branche sind das Rationalisierungsbestreben beim Einsatz von Investmentmanagern sowie die zunehmende Spätphasenspezialisierung. Aus dem festgestellten Konsolidierungs- und Reifeprozess erwächst die Herausforderung und offene Frage, wie der Markt eine solche strukturelle Angebotslücke im Frühphasensegment begegnen will. Auch das Einwerben neuer Finanzmittel sowie die aktuellen Exit-Bedingungen werden in der vorliegenden Studie kritisch beleuchtet. Als ein reizvolles Instrument zur Reduzierung der aufgezeigten Problemfelder wird dabei die aktuell unterentwickelte Syndizierung von Beteiligungsinvestitionen angesehen. Die effizientere Ausgestaltung derartiger Finanzierungsstrukturen sollte dazu beitragen, dass das private Beteiligungskapital künftig stärker bei der Transformation betrieblicher Forschung und Entwicklung zum Einsatz gelangt.
Block copolymers are receiving increasing attention in the literature. Reports on amphiphilic block copolymers have now established the basis of their self-assembly behavior: aggregate sizes, morphologies and stability can be explained from the absolute and relative block lengths, the nature of the blocks, the architecture and also solvent selectiveness. In water, self-assembly of amphiphilic block copolymers is assumed to be driven by the hydrophobic. The motivation of this thesis is to study the influence on the self-assembly in water of A b B type block copolymers (with A hydrophilic) of the variation of the hydrophilicity of B from non-soluble (hydrophobic) to totally soluble (hydrophilic). Glucose-modified polybutadiene-block-poly(N-isopropylacrylamide) copolymers were prepared and their self-assembly behavior in water studied. The copolymers formed vesicles with an asymmetric membrane with a glycosylated exterior and poly(N-isopropylacrylamide) on the inside. Above the low critical solution temperature (LCST) of poly(N-isopropylacrylamide), the structure collapsed into micelles with a hydrophobic PNIPAM core and glycosylated exterior. This collapse was found to be reversible. As a result, the structures showed a temperature-dependent interaction with L-lectin proteins and were shown to be able to encapsulate organic molecules. Several families of double hydrophilic block copolymers (DHBC) were prepared. The blocks of these copolymers were biopolymers or polymer chimeras used in aqueous two-phase partition systems. Copolymers based on dextran and poly(ethylene glycol) blocks were able to form aggregates in water. Dex6500-b-PEG5500 copolymer spontaneously formed vesicles with PEG as the “less hydrophilic” barrier and dextran as the solubilizing block. The aggregates were found to be insensitive to the polymer's architecture and concentration (in the dilute range) and only mildly sensitive to temperature. Variation of the block length, yielded different morphologies. A longer PEG chain seemed to promote more curved aggregates following the inverse trend usually observed in amphiphilic block copolymers. A shorter dextran promoted vesicular structures as usually observed for the amphiphilic counterparts. The linking function was shown to have an influence of the morphology but not on the self-assembly capability in itself. The vesicles formed by dex6500-b-PEG5500 showed slow kinetics of clustering in the presence of Con A lectin. In addition both dex6500-b-PEG5500 and its crosslinked derivative were able to encapsulate fluorescent dyes. Two additional dextran-based copolymers were synthesized, dextran-b-poly(vinyl alcohol) and dextran-b-poly(vinyl pyrrolidone). The study of their self-assembly allowed to conclude that aqueous two-phase systems (ATPS) is a valid source of inspiration to conceive DHBCs capable of self-assembling. In the second part the principle was extended to polypeptide systems with the synthesis of a poly(N-hydroxyethylglutamine)-block-poly(ethylene glycol) copolymer. The copolymer that had been previously reported to have emulsifying properties was able to form vesicles by direct dissolution of the solid in water. Last, a series of thermoresponsive copolymers were prepared, dextran-b-PNIPAMm. These polymers formed aggregates below the LCST. Their structure could not be unambiguously elucidated but seemed to correspond to vesicles. Above the LCST, the collapse of the PNIPAM chains induced the formation of stable objects of several hundreds of nanometers in radius that evolved with increasing temperature. The cooling of these solution below LCST restored the initial aggregates. This self-assembly of DHBC outside any stimuli of pH, ionic strength, or temperature has only rarely been described in the literature. This work constituted the first formal attempt to frame the phenomenon. Two reasons were accounted for the self-assembly of such systems: incompatibility of the polymer pairs forming the two blocks (enthalpic) and a considerable solubility difference (enthalpic and entropic). The entropic contribution to the positive Gibbs free energy of mixing is believed to arise from the same loss of conformational entropy that is responsible for “the hydrophobic effect” but driven by a competition for water of the two blocks. In that sense this phenomenon should be described as the “hydrophilic effect”.
Das Hauptziel dieser Arbeit ist das Verständnis der molekularen Kristallisation, sowohl mit als auch ohne polymere Additive, als einen mehrstufigen Prozess. Dieser beinhaltet eine transiente flüssig-flüssig Phasentrennung, die Nukleation von Nanokristallen in der dichten flüssigen Precursor-Phase so wie eine anschließende nanokristalline Selbstorganisation. Die Arbeit beginnt mit Untersuchungen an einem quaternären Modelsystem bestehend aus DL-Glutamat (Glu), Polyethylenimin (PEI), Wasser und Ethanol. Das Phasendiagramm dieses quaternären Systems wird durch Variation der Glu/PEI w/w und Wasser/EtOH v/v Verhältnisse bestimmt, wobei Präzpitat aus polymerinduzierten flüssigen Precursor, Koazervate oder homogene Mischungen erhalten werden Das thermodynamisch stabile Koazervat kann als Referenz für das Verständnis von flüssigen Precursorn angesehen werden, welche in der Natur metastabil und transient sind. Der mehrstufige Mechanismus der Glu-Präzipitation mit PEI als Additiv wird dann mittels Neutronen Kleinwinkelstreuung untersucht. Dies zeigt, dass die ursprünglich gebildeten flüssigen Precursor noch vor der Nukleation von Nanokristallen einen Wechsel von Wachstum und Koaleszenz durchlaufen. Die Ergebnisse aus optischer- und Eletronenmikroskopie zeigen, dass sowohl die flüssigen Precursor Superstrukturen ausbilden als auch, dass die Nukleation von Nanoplättchen in jedem einzelnen Precursor Tropfen von statten geht. Dies geschieht noch bevor sich die Nanoplättchen selbst in einer radialen Orientierung ausrichten. Diese Studie liefert die Kinetik der Präzipitation von organischen Stoffen in Gegenwart von polymeren Additiven. Eine ähnliche Vorgehensweise wie für die Herstellung von Mikrokügelchen kann für die Darstellung von gemusterten Filmen angewandt werden. Die homogene Nukleation von Nanopartikeln (NPs) findet während der Verdampfung einer quarternären DL-Lys·HCl-Polyacrylsäure-Wasser-Ethanol Dispersion auf einer hydrophilen Oberfläche statt. Die darauffolgende vollständige Verdampfung löst die Mesokristallisation eines kontinuierlichen sphärolithischen dünnen Films aus, welcher sich wiederum in einen mesokristallinen dünnen Film umwandelt. Mesokristalline Filme mit 4 Hierarchiestufen bzw. auch periodische Filme werden durch die Verdampfung der Mikrokügelchen-Dispersion erhalten. Die Ergebnisse zeigen, dass die Verdampfung eine einfache aber effektive Methode zur Herstellung von verschieden gemusterten hierarchischen Filmen darstellt. Nicht-klassische Kristallisation wird auch in der Abwesenheit von polymeren Additiven beobachtet. Wir verfolgen mittels Rasterkraftmikroskop (AFM) die Nukleation und das Wachstum einer neuen molekularen Schicht auf wachsenden DL-Glu·H2O Kristallen aus übersättigter Mutterlauge. Die Bildung einer neuen molekularen Schicht verläuft durch die Anlagerung von amorphen Nanopartikeln. Das Schrumpfen der NPs zusammen mit der strukturellen Änderung von dreidimensionalen NPs zu 2D Schichten wird während dieses Relaxationsprozesses beobachtet. Schließlich kommt es zu der Ausbildung einer neuen molekularen Schicht. Die Bildung einer molekularen Schicht durch die Anlagerung von Nanopartikeln aus der Lösung und die darauffolgende Relaxation liefert ein abweichendes Bild zu der bisher gängigen klassischen Theorie des Kristallwachstums.
Magnetische Nanopartikel bieten ein großes Potential, da sie einerseits die Eigenschaften ihrer Bulk-Materialien besitzen und anderseits, auf Grund ihrer Größe, über komplett unterschiedliche magnetische Eigenschaften verfügen können; Superparamagnetismus ist eine dieser Eigenschaften. Die meisten etablierten Anwendungen magnetischer Nanopartikel basieren heutzutage auf Eisenoxiden. Diese bieten gute magnetische Eigenschaften, sind chemisch relativ stabil, ungiftig und lassen sich auf vielen Synthesewegen relativ einfach herstellen. Die magnetischen Eigenschaften der Eisenoxide sind materialabhängig aber begrenzt, weshalb nach anderen Verbindungen mit besseren Eigenschaften gesucht werden muss. Eisencarbid (Fe3C) kann eine dieser Verbindungen sein. Dieses besitzt vergleichbare positive Eigenschaften wie Eisenoxid, jedoch viel bessere magnetische Eigenschaften, speziell eine höhere Sättigungsmagnetisierung. Bis jetzt wurde Fe3C hauptsächlich in Gasphasenabscheidungsprozessen synthetisiert oder als Nebenprodukt bei der Synthese von Kohlenstoffstrukturen gefunden. Eine Methode, mit der gezielt Fe3C-Nanopartikel und andere Metallcarbide synthetisiert werden können, ist die „Harnstoff-Glas-Route“. Neben den Metallcarbiden können mit dieser Methode auch die entsprechenden Metallnitride synthetisiert werden, was die breite Anwendbarkeit der Methode unterstreicht. Die „Harnstoff-Glas-Route“ ist eine Kombination eines Sol-Gel-Prozesses mit einer anschließenden carbothermalen Reduktion/Nitridierung bei höheren Temperaturen. Sie bietet den Vorteil einer einfachen und schnellen Synthese verschiedener Metallcarbide/nitride. Der Schwerpunkt in dieser Arbeit lag auf der Synthese von Eisencarbiden/nitriden, aber auch Nickel und Kobalt wurden betrachtet. Durch die Variation der Syntheseparameter konnten verschiedene Eisencarbid/nitrid Nanostrukturen synthetisiert werden. Fe3C-Nanopartikel im Größenbereich von d = 5 – 10 nm konnten, durch die Verwendung von Eisenchlorid, hergestellt werden. Die Nanopartikel weisen durch ihre geringe Größe superparamagnetische Eigenschaften auf und besitzen, im Vergleich zu Eisenoxid Nanopartikeln im gleichen Größenbereich, eine höhere Sättigungsmagnetisierung. Diese konnten in fortführenden Experimenten erfolgreich in ionischen Flüssigkeiten und durch ein Polymer-Coating, im wässrigen Medium, dispergiert werden. Desweiteren wurde durch ein Templatieren mit kolloidalem Silika eine mesoporöse Fe3C-Nanostruktur hergestellt. Diese konnte erfolgreich in der katalytischen Spaltung von Ammoniak getestet werden. Mit der Verwendung von Eisenacetylacetonat konnten neben Fe3C-Nanopartikeln, nur durch Variation der Reaktionsparameter, auch Fe7C3- und Fe3N-Nanopartikel synthetisiert werden. Speziell für die Fe3C-Nanopartikel konnte die Sättigungsmagnetisierung, im Vergleich zu den mit Eisenchlorid synthetisierten Nanopartikeln, nochmals erhöht werden. Versuche mit Nickelacetat führten zu Nickelnitrid (Ni3N) Nanokristallen. Eine zusätzliche metallische Nickelphase führte zu einer Selbstorganisation der Partikel in Scheiben-ähnliche Überstrukturen. Mittels Kobaltacetat konnten, in Sphären aggregierte, metallische Kobalt Nanopartikel synthetisiert werden. Kobaltcarbid/nitrid war mit den gegebenen Syntheseparametern nicht zugänglich.
In this thesis chemical reactions under hydrothermal conditions were explored, whereby emphasis was put on green chemistry. Water at high temperature and pressure acts as a benign solvent. Motivation to work under hydrothermal conditions was well-founded in the tunability of physicochemical properties with temperature, e.g. of dielectric constant, density or ion product, which often resulted in surprising reactivity. Another cornerstone was the implementation of the principles of green chemistry. Besides the use of water as solvent, this included the employment of a sustainable feedstock and the sensible use of resources by minimizing waste and harmful intermediates and additives. To evaluate the feasibility of hydrothermal conditions for chemical synthesis, exemplary reactions were performed. These were carried out in a continuous flow reactor, allowing for precise control of reaction conditions and kinetics measurements. In most experiments a temperature of 200 °C in combination with a pressure of 100 bar was chosen. In some cases the temperature was even raised to 300 °C. Water in this subcritical range can also be found in nature at hydrothermal vents on the ocean floor. On the primitive earth, environments with such conditions were however present in larger numbers. Therefore we tested whether biologically important carbohydrates could be formed at high temperature from the simple, probably prebiotic precursor formaldehyde. Indeed, this formose reaction could be carried out successfully, although the yield was lower compared to the counterpart reaction under ambient conditions. However, striking differences regarding selectivity and necessary catalysts were observed. At moderate temperatures bases and catalytically active cations like Ca2+ are necessary and the main products are hexoses and pentoses, which accumulate due to their higher stability. In contrast, in high-temperature water no catalyst was necessary but a slightly alkaline solution was sufficient. Hexoses were only formed in negligible amounts, whereas pentoses and the shorter carbohydrates accounted for the major fraction. Amongst the pentoses there was some preference for the formation of ribose. Even deoxy sugars could be detected in traces. The observation that catalysts can be avoided was successfully transferred to another reaction. In a green chemistry approach platform chemicals must be produced from sustainable resources. Carbohydrates can for instance be employed as a basis. They can be transformed to levulinic acid and formic acid, which can both react via a transfer hydrogenation to the green solvent and biofuel gamma-valerolactone. This second reaction usually requires catalysis by Ru or Pd, which are neither sustainable nor low-priced. Under hydrothermal conditions these heavy metals could be avoided and replaced by cheap salts, taking advantage of the temperature dependence of the acid dissociation constant. Simple sulfate was recognized as a temperature switchable base. With this additive high yield could be achieved by simultaneous prevention of waste. In contrast to conventional bases, which create salt upon neutralization, a temperature switchable base becomes neutral again when cooled down and thus can be reused. This adds another sustainable feature to the high atom economy of the presented hydrothermal synthesis. In a last study complex decomposition pathways of biomass were investigated. Gas chromatography in conjunction with mass spectroscopy has proven to be a powerful tool for the identification of unknowns. It was observed that several acids were formed when carbohydrates were treated with bases at high temperature. This procedure was also applied to digest wood. Afterwards it was possible to fermentate the solution and a good yield of methane was obtained. This has to be regarded in the light of the fact that wood practically cannot be used as a feedstock in a biogas factory. Thus the hydrothermal pretreatment is an efficient means to employ such materials as well. Also the reaction network of the hydrothermal decomposition of glycine was investigated using isotope-labeled compounds as comparison for the unambiguous identification of unknowns. This refined analysis allowed the identification of several new molecules and pathways, not yet described in literature. In summary several advantages could be taken from synthesis in high-temperature water. Many catalysts, absolutely necessary under ambient conditions, could either be completely avoided or replaced by cheap, sustainable alternatives. In this respect water is not only a green solvent, but helps to prevent waste and preserves resources.
Nanoporous carbon materials are widely used in industry as adsorbents or catalyst supports, whilst becoming increasingly critical to the developing fields of energy storage / generation or separation technologies. In this thesis, the combined use of carbohydrate hydrothermal carbonisation (HTC) and templating strategies is demonstrated as an efficient route to nanostructured carbonaceous materials. HTC is an aqueous-phase, low-temperature (e.g. 130 – 200 °C) carbonisation, which proceeds via dehydration / poly-condensation of carbon precursors (e.g. carbohydrates and their derivatives), allowing facile access to highly functional carbonaceous materials. Whilst possessing utile, modifiable surface functional groups (e.g. -OH and -C=O-containing moieties), materials synthesised via HTC typically present limited accessible surface area or pore volume. Therefore, this thesis focuses on the development of fabrication routes to HTC materials which present enhanced textural properties and well-defined porosity. In the first discussed synthesis, a combined hard templating / HTC route was investigated using a range of sacrificial inorganic templates (e.g. mesoporous silica beads and macroporous alumina membranes (AAO)). Via pore impregnation of mesoporous silica beads with a biomass-derived carbon source (e.g. 2-furaldehyde) and subsequent HTC at 180 oC, an inorganic / carbonaceous hybrid material was produced. Removal of the template component by acid etching revealed the replication of the silica into mesoporous carbonaceous spheres (particle size ~ 5 μm), representing the inverse morphological structure of the original inorganic body. Surface analysis (e.g. FTIR) indicated a material decorated with hydrophilic (oxygenated) functional groups. Further thermal treatment at increasingly elevated temperatures (e.g. at 350, 550, 750 oC) under inert atmosphere allowed manipulation of functionalities from polar hydrophilic to increasingly non-polar / hydrophobic structural motifs (e.g. extension of the aromatic / pseudo-graphitic nature), thus demonstrating a process capable of simultaneous control of nanostructure and surface / bulk chemistry. As an extension of this approach, carbonaceous tubular nanostructures with controlled surface functionality were synthesised by the nanocasting of uniform, linear macropores of an AAO template (~ 200 nm). In this example, material porosity could be controlled, showing increasingly microporous tube wall features as post carbonisation temperature increased. Additionally, by taking advantage of modifiable surface groups, the introduction of useful polymeric moieties (i.e. grafting of thermoresponsive poly(N-isopropylacrylamide)) was also demonstrated, potentially enabling application of these interesting tubular structures in the fields of biotechnology (e.g. enzyme immobilization) and medicine (e.g. as drug micro-containers). Complimentary to these hard templating routes, a combined HTC / soft templating route for the direct synthesis of ordered porous carbonaceous materials was also developed. After selection of structural directing agents and optimisation of synthesis composition, the F127 triblock copolymer (i.e. ethylene oxide (EO)106 propylene oxide (PO)70 ethylene oxide (EO)106) / D-Fructose system was extensively studied. D-Fructose was found to be a useful carbon precursor as the HTC process could be performed at 130 oC, thus allowing access to stable micellular phase. Thermolytic template removal from the synthesised ordered copolymer / carbon composite yielded functional cuboctahedron single crystalline-like particles (~ 5 μm) with well ordered pore structure of a near perfect cubic Im3m symmetry. N2 sorption analysis revealed a predominantly microporous carbonaceous material (i.e. Type I isotherm, SBET = 257 m2g-1, 79 % microporosity) possessing a pore size of ca. 0.9 nm. The addition of a simple pore swelling additive (e.g. trimethylbenzene (TMB)) to this system was found to direct pore size into the mesopore size domain (i.e. Type IV isotherm, SBET = 116 m2g-1, 60 % mesoporosity) generating pore size of ca. 4 nm. It is proposed that in both cases as HTC proceeds to generate a polyfuran-like network, the organised block copolymer micellular phase is essentially “templated”, either via hydrogen bonding between hydrophilic poly(EO) moiety and the carbohydrate or via hydrophobic interaction between hydrophobic poly(PO) moiety and forming polyfuran-like network, whilst the additive TMB presumably interact with poly(PO) moieties, thus swelling the hydrophobic region expanding the micelle template size further into the mesopore range.
Towards greener stationary phases : thermoresponsive and carbonaceous chromatographic supports
(2011)
Polymers which are sensitive towards external physical, chemical and electrical stimuli are termed as ‘intelligent materials’ and are widely used in medical and engineering applications. Presently, polymers which can undergo a physical change when heat is applied at a certain temperature (cloud point) in water are well-studied for this property in areas of separation chemistry, gene and drug delivery and as surface modifiers. One example of such a polymer is the poly (N-isopropylacrylamide) PNIPAAM, where it is dissolved well in water below 32 oC, while by increasing the temperature further leads to its precipitation. In this work, an alternative polymer poly (2-(2-methoxy ethoxy)ethyl methacrylate-co- oligo(ethylene glycol) methacrylate) (P(MEO2MA-co-OEGMA)) is studied due to its biocompatibility and the ability to vary its cloud points in water. When a layer of temperature responsive polymer was attached to a single continuous porous piece of silica-based material known as a monolith, the thermoresponsive characteristic was transferred to the column surfaces. The hybrid material was demonstrated to act as a simple temperature ‘switch’ in the separation of a mixture of five steroids under water. Different analytes were observed to be separated under varying column temperatures. Furthermore, more complex biochemical compounds such as proteins were also tested for separation. The importance of this work is attributed to separation processes utilizing environmentally friendly conditions, since harsh chemical environments conventionally used to resolve biocompounds could cause their biological activities to be rendered inactive.
Conventional energy sources are diminishing and non-renewable, take million years to form and cause environmental degradation. In the 21st century, we have to aim at achieving sustainable, environmentally friendly and cheap energy supply by employing renewable energy technologies associated with portable energy storage devices. Lithium-ion batteries can repeatedly generate clean energy from stored materials and convert reversely electric into chemical energy. The performance of lithium-ion batteries depends intimately on the properties of their materials. Presently used battery electrodes are expensive to be produced; they offer limited energy storage possibility and are unsafe to be used in larger dimensions restraining the diversity of application, especially in hybrid electric vehicles (HEVs) and electric vehicles (EVs). This thesis presents a major progress in the development of LiFePO4 as a cathode material for lithium-ion batteries. Using simple procedure, a completely novel morphology has been synthesized (mesocrystals of LiFePO4) and excellent electrochemical behavior was recorded (nanostructured LiFePO4). The newly developed reactions for synthesis of LiFePO4 are single-step processes and are taking place in an autoclave at significantly lower temperature (200 deg. C) compared to the conventional solid-state method (multi-step and up to 800 deg. C). The use of inexpensive environmentally benign precursors offers a green manufacturing approach for a large scale production. These newly developed experimental procedures can also be extended to other phospho-olivine materials, such as LiCoPO4 and LiMnPO4. The material with the best electrochemical behavior (nanostructured LiFePO4 with carbon coating) was able to delive a stable 94% of the theoretically known capacity.
The creation of complex polymer structures has been one of the major research topics over the last couple of decades. This work deals with the synthesis of (block co-)polymers, the creation of complex and stimuli-responsive aggregates by self-assembly, and the cross-linking of these structures. Also the higher-order self-assembly of the aggregates is investigated. The formation of poly-2-oxazoline based micelles in aqueous solution and their simultaneous functionalization and cross-linking using thiol-yne chemistry is e.g. presented. By introducing pH responsive thiols in the core of the micelles the influence of charged groups in the core of micelles on the entire structure can be studied. The charging of these groups leads to a swelling of the core and a decrease in the local concentration of the corona forming block (poly(2-ethyl-2-oxazoline)). This decrease in concentration yields a shift in the cloud point temperature to higher temperatures for this Type I thermoresponsive polymer. When the swelling of the core is prohibited, e.g. by the introduction of sufficient amounts of salt, this behavior disappears. Similar structures can be prepared using complex coacervate core micelles (C3Ms) built through the interaction of weakly acidic and basic polymer blocks. The advantage of these structures is that two different stabilizing blocks can be incorporated, which allows for more diverse and complex structures and behavior of the micelles. Using block copolymers with either a polyanionic or a polycationic block C3Ms could be created with a corona which contains two different soluble nonionic polymers, which either have a mixed corona or a Janus type corona, depending on the polymers that were chosen. Using NHS and EDC the micelles could easily be cross-linked by the formation of amide bonds in the core of the micelles. The higher-order self-assembly behavior of these core cross-linked complex coacervate core micelles (C5Ms) was studied. Due to the cross-linking the micelles are stabilized towards changes in pH and ionic strength, but polymer chains are also no longer able to rearrange. For C5Ms with a mixed corona likely network structures were formed upon the collapse of the thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm), whereas for Janus type C5Ms well defined spherical aggregates of micelles could be obtained, depending on the pH of the solution. Furthermore it could be shown that Janus micelles can adsorb onto inorganic nanoparticles such as colloidal silica (through a selective interaction between PEO and the silica surface) or gold nanoparticles (by the binding of thiol end-groups). Asymmetric aggregates were also formed using the streptavidin-biotin binding motive. This is achieved by using three out of the four binding sites of streptavidin for the binding of one three-arm star polymer, end-functionalized with biotin groups. A homopolymer with one biotin end-group can be used to occupy the last position. This binding of two different polymers makes it possible to create asymmetric complexes. This phase separation is theoretically independent of the kind of polymer since the structure of the protein is the driving force, not the intrinsic phase separation between polymers. Besides Janus structures also specific cross-linking can be achieved by using other mixing ratios.
The needs for sustainable energy generation, but also a sustainable chemistry display the basic motivation of the current thesis. By different single investigated cases, which are all related to the element carbon, the work can be devided into two major topics. At first, the sustainable synthesis of “useful” carbon materials employing the process of hydrothermal carbonisation (HC) is described. In the second part, the synthesis of heteroatom - containing carbon materials for electrochemical and fuel cell applications employing ionic liquid precursors is presented. On base of a thorough review of the literature on hydrothermolysis and hydrothermal carbonisation of sugars in addition to the chemistry of hydroxymethylfurfural, mechanistic considerations of the formation of hydrothermal carbon are proposed. On the base of these reaction schemes, the mineral borax, is introduced as an additive for the hydrothermal carbonisation of glucose. It was found to be a highly active catalyst, resulting in decreased reaction times and increased carbon yields. The chemical impact of borax, in the following is exploited for the modification of the micro- and nanostructure of hydrothermal carbon. From the borax - mediated aggregation of those primary species, widely applicable, low density, pure hydrothermal carbon aerogels with high porosities and specific surface areas are produced. To conclude the first section of the thesis, a short series of experiments is carried out, for the purpose of demonstrating the applicability of the HC model to “real” biowaste i.e. watermelon waste as feedstock for the production of useful materials. In part two cyano - containing ionic liquids are employed as precursors for the synthesis of high - performance, heteroatom - containing carbon materials. By varying the ionic liquid precursor and the carbonisation conditions, it was possible to design highly active non - metal electrocatalyst for the reduction of oxygen. In the direct reduction of oxygen to water (like used in polymer electrolyte fuel cells), compared to commercial platinum catalysts, astonishing activities are observed. In another example the selective and very cost efficient electrochemical synthesis of hydrogen peroxide is presented. In a last example the synthesis of graphitic boron carbon nitrides from the ionic liquid 1 - Ethyl - 3 - methylimidazolium - tetracyanoborate is investigated in detail. Due to the employment of unreactive salts as a new tool to generate high surface area these materials were first time shown to be another class of non - precious metal oxygen reduction electrocatalyst.
Klausurenkurs im Europarecht
(2011)
Am 20. November 2010 fand an der Universität Potsdam das 4. Herbsttreffen Patholinguistik statt. Die Konferenzreihe wird regelmäßig seit 2007 vom Verband für Patholinguistik e.V. (vpl) durchgeführt. Der vorliegende Tagungsband veröffentlicht die Hauptvorträge des Herbsttreffens zum Thema "Lesen lernen: Diagnostik und Therapie bei Störungen des Leseerwerbs". Des Weiteren sind die Beiträge promovierender bzw. promovierter PatholinguistInnen sowie der Posterpräsentationen enthalten.
From CDM to REDD+ - what do we know for setting up effective and legitimate carbon governance?
(2011)
This article compares two carbon governance instruments - the Clean Development Mechanism (CDM) and Reducing Emissions from Deforestation and Degradation (REDD+) - to assess lessons from the former for the latter regarding effectiveness and legitimacy of such instruments. The article argues that the CDM has a relatively high degree of output-oriented legitimacy resulting in effectiveness and some input-oriented legitimacy, with few discernible tradeoffs between them. In contrasting this to REDD+, the hypotheses are advanced that (i) output-oriented legitimacy/effectiveness can again be achieved but that (ii) a higher degree of input-oriented legitimacy is necessary for REDD+ and thus also a certain trade-off between the two forms of legitimacy can be expected. This is shown through comparing the technologies and methodologies, economic rationales, political support, regulatory structures, and environmental impacts of both instruments.
The conclusion to the special section has three objectives: First, it argues that a focus on "practice" implicitly connects all the articles in the special section and thereby reinforces the core points of the analytical framework introduced by Fuchs and Glaab. Second, the paper summarizes the main messages of the articles by identifying three red threads that are dominant in all four contributions. These are the strong focus of all authors on ideational forces, an emphasis on the role of academics and the description of complexities of local-global interdependencies. Third, some common blind spots are identified that merit future research.
Inhalt: - I. Die N-Entwicklungszusammenarbeit war zu starr und ineffizient – umfassende Reformen wurden Ende der 90er Jahre durchgeführt. - II. UN-Entwicklungszusammenarbeit ist politischer geworden – mehr Politikkohärenz, neue Partnerschaften und demokratischere Regierungsführung werden gefordert - 1. Mehr Politikkohärenz - 2. Neue Partnerschaften - 3. Demokratische Regierungsführung - II. UN-Entwicklungszusammenarbeit wird strategischer umgesetzt – Ausrichtung an Millenniumszielen, harmonisierte Programmhilfe, und ergebnisorientiertes Management werden erwartet - 1. Ausrichtung an den Millenniumszielen der UN - 2. Harmonisierte Programmhilfe - 3. Ergebnisorientiertes Management - III. Schlußfolgerungen - Literatur
Im Auftrag des Staates
(2011)
Folter ist ein Akt extremer kollektiver Gewalt, der im Auftrag eines Staates im Geheimen ausgeübt wird. Die Frage, was Menschen dazu bringt, anderen Menschen diese extreme Gewalt anzutun, verengt den Blick für ein Verständnis der Folter allzu schnell auf individualistische Erklärungsversuche. Der vorliegende Aufsatz geht im Gegensatz dazu von der Gruppe der Folterer aus und rückt die sozialen Beziehungen dieser Form der Vergesellschaftung und die von ihnen ausgehenden sozialen Dynamiken und Effekte in den Mittelpunkt. In einem ersten Schritt werden Georg Simmels formale Bestimmungen der geheimen Gesellschaft rekonstruiert und auf die geheime Gesellschaft der Folterer angewandt und spezifiziert; auf dieser Grundlage werden im zweiten Schritt Handlungsbedingungen der Mitglieder der geheimen Gesellschaft der Folterer herausgearbeitet; der dritte Schritt bestimmt die eigendynamischen Prozesse des Phänomens der Folter, die aus der Eskalation politischer Konflikte, der Gruppe der Folterer und der Situation der Folter erwachsen. Die These lautet, dass sich aus der Perspektive einer relationalen Soziologie ein theoretischer Zugriff auf das Problem der Folter ergibt, der weiterführende Erklärungen des Phänomens ermöglicht.
Rechtsextremismus und Raum
(2011)
Torture is an extreme act of collective violence that is secretly executed in the name of a state. In order to explain the reasons why people torture others, individualist approaches concentrate on individuals' motives or interests. Contrary to that, the article argues that torture should be understood as a social relation. Thus, it takes the social relations of the group of torturers as a starting point. Firstly, following Georg Simmel's analysis of the secret society the paper argues that the group of torturers can adequately be conceptualized as a secret society; secondly, against this background the article reconstructs the conditions which structure torturers' agency; finally, this article offers an outline of the processes and dynamics that allows for explaining the phenomenon of torture. The thesis of the article argues that a relational sociology helps better explain and understand the social phenomenon of torture.
The new pi-conjugated 1,2,3-triazol-1,4-diyl fluoroionophore 1 generated via Cu(I) catalyzed [3 + 2] cycloaddition shows high fluorescence enhancement factors (FEF) in the presence of Na+ (FEF = 58) and K+ (FEF = 27) in MeCN and high selectivity towards K+ under simulated physiological conditions (160 mM K+ or Na+, respectively) with a FEF of 2.5 for K+.
Glacial advances constrained by Be-10 exposure dating of bedrock landslides, Kyrgyz Tien Shan
(2011)
Numerous large landslide deposits occur in the Tien Shan, a tectonically active intraplate orogen in Central Asia. Yet their significance in Quaternary landscape evolution and natural hazard assessment remains unresolved due to the lack of "absolute" age constraints. Here we present the first Be-10 exposure ages for three prominent (>10(7) m(3)) bedrock landslides that blocked major rivers and formed lakes, two of which subsequently breached, in the northern Kyrgyz Tien Shan. Three Be-10 ages reveal that one landslide in the Alamyedin River occurred at 11-15 ka, which is consistent with two C-14 ages of gastropod shells from reworked loess capping the landslide. One large landslide in Aksu River is among the oldest documented in semi-arid continental interiors, with a Be-10 age of 63-67 ka. The Ukok River landslide deposit(s) yielded variable Be-10 ages, which may result from multiple landslides, and inheritance of Be-10. Two Be-10 ages of 8.2 and 5.9 ka suggest that one major landslide occurred in the early to mid-Holocene, followed by at least one other event between 1.5 and 0.4 ka. Judging from the regional glacial chronology, all three landslides have occurred between major regional glacial advances. Whereas Alamyedin and Ukok can be considered as postglacial in this context, Aksu is of interglacial age. None of the landslide deposits show traces of glacial erosion, hence their locations and I Be ages mark maximum extents and minimum ages of glacial advances, respectively. Using toe-to-headwall altitude ratios of 0.4-0.5, we reconstruct minimum equilibrium-line altitudes that exceed previous estimates by as much as 400 m along the moister northern fringe of the Tien Shan. Our data show that deposits from large landslides can provide valuable spatio-temporal constraints for glacial advances in landscapes where moraines and glacial deposits have low preservation potential. (C) 2011 University of Washington. Published by Elsevier Inc. All rights reserved.
Context. Extrapolations of solar photospheric vector magnetograms into three-dimensional magnetic fields in the chromosphere and corona are usually done under the assumption that the fields are force-free. This condition is violated in the photosphere itself and a thin layer in the lower atmosphere above. The field calculations can be improved by preprocessing the photospheric magnetograms. The intention here is to remove a non-force-free component from the data.
Aims. We compare two preprocessing methods presently in use, namely the methods of Wiegelmann et al. (2006, Sol. Phys., 233, 215) and Fuhrmann et al. (2007, A&A, 476, 349).
Methods. The two preprocessing methods were applied to a vector magnetogram of the recently observed active region NOAA AR 10 953. We examine the changes in the magnetogram effected by the two preprocessing algorithms. Furthermore, the original magnetogram and the two preprocessed magnetograms were each used as input data for nonlinear force-free field extrapolations by means of two different methods, and we analyze the resulting fields.
Results. Both preprocessing methods managed to significantly decrease the magnetic forces and magnetic torques that act through the magnetogram area and that can cause incompatibilities with the assumption of force-freeness in the solution domain. The force and torque decrease is stronger for the Fuhrmann et al. method. Both methods also reduced the amount of small-scale irregularities in the observed photospheric field, which can sharply worsen the quality of the solutions. For the chosen parameter set, the Wiegelmann et al. method led to greater changes in strong-field areas, leaving weak-field areas mostly unchanged, and thus providing an approximation of the magnetic field vector in the chromosphere, while the Fuhrmann et al. method weakly changed the whole magnetogram, thereby better preserving patterns present in the original magnetogram. Both preprocessing methods raised the magnetic energy content of the extrapolated fields to values above the minimum energy, corresponding to the potential field. Also, the fields calculated from the preprocessed magnetograms fulfill the solenoidal condition better than those calculated without preprocessing.
In Czech, German, and many other languages, part of the semantic focus of the utterance can be moved to the left periphery of the clause. The main generalization is that only the leftmost accented part of the semantic focus can be moved. We propose that movement to the left periphery is generally triggered by an unspecific edge feature of C (Chomsky 2008) and its restrictions can be attributed to requirements of cyclic linearization, modifying the theory of cyclic linearization developed by Fox and Pesetsky (2005). The crucial assumption is that structural accent is a direct consequence of being linearized at merge, thus it is indirectly relevant for (locality restrictions on) movement. The absence of structural accent correlates with givenness. Given elements may later receive (topic or contrastive) accents, which accounts for fronting in multiple focus/contrastive topic constructions. Without any additional assumptions, the model can account for movement of pragmatically unmarked elements to the left periphery ('formal fronting', Frey 2005). Crucially, the analysis makes no reference at all to concepts of information structure in the syntax, in line with the claim of Chomsky (2008) that UG specifies no direct link between syntax and information structure.
The claim that focus evokes a set of alternatives is a central issue in several accounts of the effects of focus on interpretation. This article presents two empirical studies that examine whether this property of focus is independent of contextual conditions. The syntactic operation at issue is object-fronting in German, Spanish, Greek, and Hungarian licensed by contexts involving focus on the object constituent. This operation evokes the intuition that the fronted referent excludes some or all relevant alternatives. The presented experiments deal with the question whether this interpretative property obligatorily accompanies the operation at issue or not. The empirical findings show that in German, Spanish, and Greek this intuition depends on properties of the context and is sensitive to the interaction with further discourse factors (in particular, the predictability of the referent). Hungarian displays a different data pattern: our data does not provide evidence that the syntactic operation at issue depends on the context or interacts with further discourse factors. This finding is in line with the view that evoking alternatives is inherent part of constituent-fronting in this language.
This article deals with the claim that the MAGNITUDE ESTIMATION (ME) method of gathering acceptability judgments produces data that are more informative for linguists than binary or n-point scale judgments. We performed three acceptability-rating experiments that directly compared ME data to binary and seven-point scale data. The results clearly falsify the hypothesis that data gathered by the ME method carry a larger amount of information about the acceptability of a given linguistic phenomenon. The three measures are largely equivalent with respect to informativity. Moreover, ME judgments are shown to be more liable to producing spurious variance under certain circumstances.*
This article presents several acceptability rating experiments concerned with crossing wh-movement in German multiple questions. Our results show that there is no general superiority effect in German, thus refuting claims to the contrary by Featherston (2005). However, acceptability is reduced when a wh-phrase crosses a wh-subject with which it agrees in animacy. We explain this finding in terms of the availability of different sorting keys for the answers to the multiple questions.
Love, Lust and Load the Pill as a female Generation experience in the Federal Republic 1960-1980
(2011)
Alte These – neuer Aufguss
(2011)
This is the 16th issue of the working paper series Interdisciplinary Studies on Information Structure (ISIS) of the Sonderforschungsbereich (SFB) 632. The present issue continues the series on Linguistic Fieldnotes providing data elicited and documented by different members of the Sonderforschungsbereich 632. Here, the focus is placed on primary linguistic data from Gur and Kwa languages, collected and prepared by Anne Schwarz, former investigator in Project B1 and D2, and Ines Fiedler, former investigator in Project B1 and D2 and current member of Project B7 at Humboldt-Universität zu Berlin.
Akademischer Sittenverfall?
(2011)
rezensiertes Werk: Marx, Peter W.:Ein theatralisches Zeitalter : Bürgerliche Selbstinszenierungen um 1900. - Tübingen [u.a.] : A. Francke, 2008. - 429 S. ISBN 978-3-772-08220-7
Kinderrechte ohne Vorbehalt
(2011)
Wiederkehr des Immergleichen
(2011)
Mathematical modeling of biological phenomena has experienced increasing interest since new high-throughput technologies give access to growing amounts of molecular data. These modeling approaches are especially able to test hypotheses which are not yet experimentally accessible or guide an experimental setup. One particular attempt investigates the evolutionary dynamics responsible for today's composition of organisms. Computer simulations either propose an evolutionary mechanism and thus reproduce a recent finding or rebuild an evolutionary process in order to learn about its mechanism. The quest for evolutionary fingerprints in metabolic and gene-coexpression networks is the central topic of this cumulative thesis based on four published articles. An understanding of the actual origin of life will probably remain an insoluble problem. However, one can argue that after a first simple metabolism has evolved, the further evolution of metabolism occurred in parallel with the evolution of the sequences of the catalyzing enzymes. Indications of such a coevolution can be found when correlating the change in sequence between two enzymes with their distance on the metabolic network which is obtained from the KEGG database. We observe that there exists a small but significant correlation primarily on nearest neighbors. This indicates that enzymes catalyzing subsequent reactions tend to be descended from the same precursor. Since this correlation is relatively small one can at least assume that, if new enzymes are no "genetic children" of the previous enzymes, they certainly be descended from any of the already existing ones. Following this hypothesis, we introduce a model of enzyme-pathway coevolution. By iteratively adding enzymes, this model explores the metabolic network in a manner similar to diffusion. With implementation of an Gillespie-like algorithm we are able to introduce a tunable parameter that controls the weight of sequence similarity when choosing a new enzyme. Furthermore, this method also defines a time difference between successive evolutionary innovations in terms of a new enzyme. Overall, these simulations generate putative time-courses of the evolutionary walk on the metabolic network. By a time-series analysis, we find that the acquisition of new enzymes appears in bursts which are pronounced when the influence of the sequence similarity is higher. This behavior strongly resembles punctuated equilibrium which denotes the observation that new species tend to appear in bursts as well rather than in a gradual manner. Thus, our model helps to establish a better understanding of punctuated equilibrium giving a potential description at molecular level. From the time-courses we also extract a tentative order of new enzymes, metabolites, and even organisms. The consistence of this order with previous findings provides evidence for the validity of our approach. While the sequence of a gene is actually subject to mutations, its expression profile might also indirectly change through the evolutionary events in the cellular interplay. Gene coexpression data is simply accessible by microarray experiments and commonly illustrated using coexpression networks where genes are nodes and get linked once they show a significant coexpression. Since the large number of genes makes an illustration of the entire coexpression network difficult, clustering helps to show the network on a metalevel. Various clustering techniques already exist. However, we introduce a novel one which maintains control of the cluster sizes and thus assures proper visual inspection. An application of the method on Arabidopsis thaliana reveals that genes causing a severe phenotype often show a functional uniqueness in their network vicinity. This leads to 20 genes of so far unknown phenotype which are however suggested to be essential for plant growth. Of these, six indeed provoke such a severe phenotype, shown by mutant analysis. By an inspection of the degree distribution of the A.thaliana coexpression network, we identified two characteristics. The distribution deviates from the frequently observed power-law by a sharp truncation which follows after an over-representation of highly connected nodes. For a better understanding, we developed an evolutionary model which mimics the growth of a coexpression network by gene duplication which underlies a strong selection criterion, and slight mutational changes in the expression profile. Despite the simplicity of our assumption, we can reproduce the observed properties in A.thaliana as well as in E.coli and S.cerevisiae. The over-representation of high-degree nodes could be identified with mutually well connected genes of similar functional families: zinc fingers (PF00096), flagella, and ribosomes respectively. In conclusion, these four manuscripts demonstrate the usefulness of mathematical models and statistical tools as a source of new biological insight. While the clustering approach of gene coexpression data leads to the phenotypic characterization of so far unknown genes and thus supports genome annotation, our model approaches offer explanations for observed properties of the coexpression network and furthermore substantiate punctuated equilibrium as an evolutionary process by a deeper understanding of an underlying molecular mechanism.
Stadtstruktur und Umwelt
(2011)
Im nachfolgenden Beitrag wird die Frage diskutiert, welche Strukturveränderungen Städte durch klimapolitisch motivierte Stadtplanung und -gestaltung erfahren. Es wird gezeigt, dass selbst tiefgreifende Veränderungen der bestehenden Stadtstrukturen durch Resuburbanisierung und durch das Prinzip der räumlichen Konzentration von Arbeiten und Wohnen nur marginale – wenn überhaupt – Beiträge zu den sogenannten "Klimazielen" leisten, wobei diese in der Klimaforschung nicht unumstritten sind, da der kausale Zusammenhang zwischen Klimaänderung und anthropogenen Emissionen nicht eindeutig geklärt ist.
Saccades move objects of interest into the center of the visual field for high-acuity visual analysis. White, Stritzke, and Gegenfurtner (Current Biology, 18, 124–128, 2008) have shown that saccadic latencies in the context of a structured background are much shorter than those with an unstructured background at equal levels of visibility. This effect has been explained by possible preactivation of the saccadic circuitry whenever a structured background acts as a mask for potential saccade targets. Here, we show that background textures modulate rates of microsaccades during visual fixation. First, after a display change, structured backgrounds induce a stronger decrease of microsaccade rates than do uniform backgrounds. Second, we demonstrate that the occurrence of a microsaccade in a critical time window can delay a subsequent saccadic response. Taken together, our findings suggest that microsaccades contribute to the saccadic facilitation effect, due to a modulation of microsaccade rates by properties of the background.
We present an alarm-based earthquake forecast model that uses the early aftershock statistics (EAST). This model is based on the hypothesis that the time delay before the onset of the power-law aftershock decay rate decreases as the level of stress and the seismogenic potential increase. Here, we estimate this time delay from < t(g)>, the time constant of the Omori-Utsu law. To isolate space-time regions with a relative high level of stress, the single local variable of our forecast model is the E-a value, the ratio between the long-term and short-term estimations of < t(g)>. When and where the E-a value exceeds a given threshold (i.e., the c value is abnormally small), an alarm is issued, and an earthquake is expected to occur during the next time step. Retrospective tests show that the EAST model has better predictive power than a stationary reference model based on smoothed extrapolation of past seismicity. The official prospective test for California started on 1 July 2009 in the testing center of the Collaboratory for the Study of Earthquake Predictability (CSEP). During the first nine months, 44 M >= 4 earthquakes occurred in the testing area. For this time period, the EAST model has better predictive power than the reference model at a 1% level of significance. Because the EAST model has also a better predictive power than several time-varying clustering models tested in CSEP at a 1% level of significance, we suggest that our successful prospective results are not due only to the space-time clustering of aftershocks.
The present article analyzes the socio-economic background of maths teachers in Germany and its relation to career-related decisions and job-related convictions. These analyzes is based on data collected through questionnaires answered by 1126 maths teachers working at a sample of secondary schools representative of Germany. Following Bourdieu's theory, the authors examine whether the economic and cultural conditions prevailing in the teachers' families of origin are related to their decision to pursue this specific professional career or to their job-related convictions. Furthermore, it is analyzed in how far teachers, in their everyday work in the classroom, meet students from groups of origin foreign to the teachers themselves. The results show that the teachers, socio-economic background has no systematic relation to either their career-related decisions or their job-related convictions.
High class students in the universities, the rest in the other institutions of higher education
(2011)
In Germany, different types of university-level institutions are available for tertiary education: traditional universities (Universitaten) and-since the 1970s-universities of applied science (Fachhochschulen) as well as universities of cooperative education (Berufsakademien). The present study investigates differences in key areas related to students' academic choices and success: do students at different types of university differ significantly in terms of cognitive performance, personality or social background? We compared N = 1.230 students at traditional universities, universities of applied science, and universities of cooperative education (Baden-Wurttemberg Cooperative State University) on the basis of a large scale longitudinal study in the German federal state of Baden-Wurttemberg. Students of the different university types differed significantly in all three key areas (cognitive performance, personality, and social background) within the fields of technical sciences and economics. We determine the relative importance of these key areas for differences between university types and we discuss the implications of our findings.
Efforts to break the link between the school type attended and the qualification awarded are seen an important step in the modernization of Germany's tracked secondary school system. However, it remains disputed whether these efforts have reduced social disparities or in fact increased them. This study examined the transition from lower secondary education in academic- and intermediate-track schools to upper secondary education in general and vocational gymnasium schools in the state of Baden-Wurttemberg. When indicators of parental social background and school-leaving qualifications were controlled, the opening of upper secondary education was found to be associated with a decrease in the social selectivity of upper secondary education for intermediate-track students. At the same time, for those intermediate-track students who were entitled to enter upper secondary education, social background had predictive effects on the transition decision; however, the overall size of these effects was low.
The Casimir-Polder interaction between a single neutral atom and a nearby surface, arising from the (quantum and thermal) fluctuations of the electromagnetic field, is a cornerstone of cavity quantum electrodynamics (cQED), and theoretically well established. Recently, Bose-Einstein condensates (BECs) of ultracold atoms have been used to test the predictions of cQED. The purpose of the present thesis is to upgrade single-atom cQED with the many-body theory needed to describe trapped atomic BECs. Tools and methods are developed in a second-quantized picture that treats atom and photon fields on the same footing. We formulate a diagrammatic expansion using correlation functions for both the electromagnetic field and the atomic system. The formalism is applied to investigate, for BECs trapped near surfaces, dispersion interactions of the van der Waals-Casimir-Polder type, and the Bosonic stimulation in spontaneous decay of excited atomic states. We also discuss a phononic Casimir effect, which arises from the quantum fluctuations in an interacting BEC.
We analyze the equilibrium properties of a weakly interacting, trapped quasi-one-dimensional Bose gas at finite temperatures and compare different theoretical approaches. We focus in particular on two stochastic theories: a number-conserving Bogoliubov (NCB) approach and a stochastic Gross-Pitaevskii equation (SGPE) that have been extensively used in numerical simulations. Equilibrium properties like density profiles, correlation functions, and the condensate statistics are compared to predictions based upon a number of alternative theories. We find that due to thermal phase fluctuations, and the corresponding condensate depletion, the NCB approach loses its validity at relatively low temperatures. This can be attributed to the change in the Bogoliubov spectrum, as the condensate gets thermally depleted, and to large fluctuations beyond perturbation theory. Although the two stochastic theories are built on different thermodynamic ensembles (NCB, canonical; SGPE, grand-canonical), they yield the correct condensate statistics in a large Bose-Einstein condensate (BEC) (strong enough particle interactions). For smaller systems, the SGPE results are prone to anomalously large number fluctuations, well known for the grand-canonical, ideal Bose gas. Based on the comparison of the above theories to the modified Popov approach, we propose a simple procedure for approximately extracting the Penrose-Onsager condensate from first-and second-order correlation functions that is both computationally convenient and of potential use to experimentalists. This also clarifies the link between condensate and quasicondensate in the Popov theory of low-dimensional systems.
Atom chips are a promising candidate for a scalable architecture for quantum information processing provided a universal set of gates can be implemented with high fidelity. The difficult part in achieving universality is the entangling two-qubit gate. We consider a Rydberg phase gate for two atoms trapped on a chip and employ optimal control theory to find the shortest gate that still yields a reasonable gate error. Our parameters correspond to a situation where the Rydberg blockade regime is not yet reached. We discuss the role of spontaneous emission and the effect of noise from the chip surface on the atoms in the Rydberg state.
We show how the spontaneous emission rate of an excited two-level atom placed in a trapped Bose-Einstein condensate of ground-state atoms is enhanced by bosonic stimulation. This stimulation depends on the overlap of the excited matter-wave packet with the macroscopically occupied condensate wave function, and provides a probe of the spatial coherence of the Bose gas. The effect can be used to amplify the distance-dependent decay rate of an excited atom near an interface.
Annelida, the ringed worms, is a highly diverse animal phylum that includes more than 15,000 described species and constitutes the dominant benthic macrofauna from the intertidal zone down to the deep sea. A robust annelid phylogeny would shape our understanding of animal body-plan evolution and shed light on the bilaterian ground pattern. Traditionally, Annelida has been split into two major groups: Clitellata (earthworms and leeches) and polychaetes (bristle worms), but recent evidence suggests that other taxa that were once considered to be separate phyla (Sipuncula, Echiura and Siboglinidae (also known as Pogonophora)) should be included in Annelida(1-4). However, the deep-level evolutionary relationships of Annelida are still poorly understood, and a robust reconstruction of annelid evolutionary history is needed. Here we show that phylogenomic analyses of 34 annelid taxa, using 47,953 amino acid positions, recovered a well-supported phylogeny with strong support for major splits. Our results recover chaetopterids, myzostomids and sipunculids in the basal part of the tree, although the position of Myzostomida remains uncertain owing to its long branch. The remaining taxa are split into two clades: Errantia (which includes the model annelid Platynereis), and Sedentaria (which includes Clitellata). Ancestral character trait reconstructions indicate that these clades show adaptation to either an errant or a sedentary lifestyle, with alteration of accompanying morphological traits such as peristaltic movement, parapodia and sensory perception. Finally, life history characters in Annelida seem to be phylogenetically informative.
Phylogenetic analyses using genome-scale data sets must confront incongruence among gene trees, which in plants is exacerbated by frequent gene duplications and losses. Gene tree parsimony (GTP) is a phylogenetic optimization criterion in which a species tree that minimizes the number of gene duplications induced among a set of gene trees is selected. The run time performance of previous implementations has limited its use on large-scale data sets. We used new software that incorporates recent algorithmic advances to examine the performance of GTP on a plant data set consisting of 18,896 gene trees containing 510,922 protein sequences from 136 plant taxa (giving a combined alignment length of >2.9 million characters). The relationships inferred from the GTP analysis were largely consistent with previous large-scale studies of backbone plant phylogeny and resolved some controversial nodes. The placement of taxa that were present in few gene trees generally varied the most among GTP bootstrap replicates. Excluding these taxa either before or after the GTP analysis revealed high levels of phylogenetic support across plants. The analyses supported magnoliids sister to a eudicot + monocot clade and did not support the eurosid I and II clades. This study presents a nuclear genomic perspective on the broad-scale phylogenic relationships among plants, and it demonstrates that nuclear genes with a history of duplication and loss can be phylogenetically informative for resolving the plant tree of life.
Permanent genetic resources added to molecular ecology resources database 1 April 2011-31 May 2011
(2011)
This article documents the addition of 92 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Anopheles minimus, An. sinensis, An. dirus, Calephelis mutica, Lutjanus kasmira, Murella muralis and Orchestia montagui. These loci were cross-tested on the following species: Calephelis arizonensi, Calephelis borealis, Calephelis nemesis, Calephelis virginiensis and Lutjanus bengalensis.
Self-assembly phenomena in block copolymer systems are attracting considerable interest from the scientific community and industry alike. Particularly interesting is the behavior of amphiphilic copolymers, which can self-organize into nanoscale-sized objects such as micelles, vesicles, or tubes in solution, and which form well-defined assemblies at interfaces such as air-liquid, air-solid, or liquid-solid. Depending on the polymer chemistry and architecture, various types of organization at interfaces can be expected, and further exploited for applications in nanotechnology, electronics, and biomedical sciences.
In this article, we discuss the formation and characterization of Langmuir monolayers from various amphiphilic block copolymers, including chargeable and thus pH-responsivematerials. Solid-supported polymer films are reviewed in the context of alteration of surface properties by ultrathin polymer layers and the possibilities for application in tissue engineering, sensors and biomaterials. Finally, we focus on how organic and polymer monolayers influence the growth of inorganic materials. This is a truly biomimetic approach since Nature uses soft interfaces to control the nucleation, growth, and morphology of biominerals such as calcium phosphate, calcium carbonate, and silica.
Objectives: Stroke, frequently a consequence of hypertension, is one of the leading causes of death and neurological disabilities worldwide. In the ischemic brain, levels of endothelin-1, one of the most potent vasoconstrictors, are raised. Anti-inflammatory and neuroprotective effects of endothelin antagonists after stroke have been described in literature. Based on these findings, we investigated the protective effect of the endothelin converting enzyme/neutral endopeptidase blocker, SLV 338, in salt-loaded, stroke-prone, spontaneously hypertensive rats.
Methods: Male, 8-week-old spontaneously hypertensive stroke-prone rats were put on a high salt diet and treated with either 30 mg/kg or 100 mg/kg SLV 338 or vehicle for 27 weeks. Blood pressure, neurological outcome, body weight, and mortality were investigated throughout treatment. In weeks 1 and 9, animals were housed in metabolic cages for collection of urinary and blood samples and assessment of salt water and food intake. In weeks 22 and 27, additional blood samples were taken. At the end of the study, all brains were analyzed using magnetic resonance imaging.
Results: SLV 338 was well tolerated in all animals. Neurological outcome and infarct size were similar in all groups. Albuminuria was considerably delayed and the incidence of stroke significantly lowered in treated animals. In spontaneously hypertensive stroke-prone rats, treatment with SLV 338 significantly (P=0.01) improved survival in comparison to the vehicle treated group in a blood pressure-independent manner.
Discussion: Our data in spontaneously hypertensive stroke-prone rats demonstrate that combined endothelin converting enzyme/neutral endopeptidase inhibition could offer a new therapeutic approach for primary stroke prevention and improvement of mortality. The mechanism seems to be blood pressure-independent.
Japan in der Katastrophe
(2011)
Die verheerenden Erdbeben im März dieses Jahres erschütterten nicht nur Japan, sie erschütterten die Welt. Das Reaktorunglück von Fukushima weckte düstere Erinnerungen an Tschernobyl. Wie geht das asiatische Land mit der Katastrophe um? Das Thema zeigt deutlich, dass die Krise noch lange nicht Überwunden ist. Weitere Themen: Europa macht die Eurokrise zu schaffen. Werner Weidenfeld kritisiert die Verengung und plädiert für ein politisches Projekt Europa. Berlins Große Politik im Fall Libyen analysiert Gunther Hellmann. Zudem ein aktuelles Interview mit dem Generaldelegierten Palästinas in Deutschland: Palästinas Antrag auf UN-Vollmitgliedschaft im September 2011 – Lösung des Knotens oder Verschärfung der Auseinandersetzung?
Aus dem Inhalt: - Neue Entwicklungen im regionalen Menschenrechtsschutz: eine politikwissenschaftliche Betrachtung des institutionellen Designs und der Dynamik des derzeitigen menschenrechtlichen Regionalismus - Das menschenrechtliche Diskriminierungsverbot und seine Grenzen - Die Individualbeschwerde zur Kinderrechtskonvention - BVerfG: Fraport – Urteil vom 22. Februar 2011
Das vorliegende Heft 16 der Reihe Studien zu Grund- und Menschenrechten enthält den Tagungsband zum Workshop „Mechanismen zur Folterverhütung im Vergleich“, welcher am 6. und 7. Oktober 2010 in Potsdam stattfand und die unterschiedlichen Mechanismen zur Folterprävention auf universeller, regionaler und nationaler Ebene beleuchtete.
Article 1 A, para. 2
(2011)
Article 33, para. 2
(2011)
Article 1 F
(2011)