Moduli Stabilization and Inflationary Cosmology with Poly-Instantons in Type IIB Orientifolds

Equipped with concrete examples of Type IIB orientifolds featuring poly-instanton corrections to the superpotential, the effects on moduli stabilization and inflationary cosmology are analyzed. Working in the framework of the LARGE volume scenario, the Kaehler modulus related to the size of the four-cycle supporting the poly-instanton contributes sub-dominantly to the scalar potential. It is shown that this Kaehler modulus gets stabilized and, by displacing it from its minimum, can play the role of an inflaton. Subsequent cosmological implications are discussed and compared to experimental data.Comment: 38 pages, 7 figures, Reference added, Typo fixed, Published versio

Zeitreihenanalysen an Holz: Dendrochronologie - Allgemeine Grundlagen der Jahrringforschung

Was ist eigentlich Dendrochronologie? Und wie kann sie für Historiker*innen nützlich sein? Diese und weitere Fragen klärt der Beitrag und führt damit in die Arbeitsweise der Jahrringforschung ein

First Dendrochronological Datings of Historical Timber in Albania

Die dendrochronologischen Untersuchungen wurden hauptsächlich an Hölzern aus der Region Korça im Südosten Albaniens vorgenommen. Die Proben stammen von rezenten Bäumen, aus Kirchen, Profangebäuden, von Ikonen sowie von Pfählen prähistorischer Seeufersiedlungen vom Großen Prespasee und von der makedonischen Seite des Ohridsees. Die Mehrheit der insgesamt 564 Proben stammt von Nadelbäumen, insbesondere Schwarzkiefern (Pinus nigra), Bergkiefern (Pinus heldreichii), Tannen (Abies sp.) und in prähistorischer Zeit auch Wacholder (Juniperus sp.). Laubhölzer wie Buchen (Fagus sp.) und Eichen (Quercus sp.) konnten bislang nur in weitaus geringerem Umfang beprobt werden. Die Proben ermöglichten den Aufbau von Jahrringmittelwertserien aus dem Neolithikum (6. Jt.), der Mittelbronzezeit (3. Jt.) sowie aus Mittelalter und Neuzeit. Absolute Datierungen gelangen vorerst nur für Holzfunde der letzten 1000 Jahre. Bisher konnten 219 Jahrringserien von 36 Ikonen und sieben Gebäuden datiert werden. Außerdem werden Aspekte von Klimageschichte, Bau- und Kunstgeschichte sowie historische Waldnutzungsformen angesprochen. Die Weiterführung dieser Untersuchungen trägt wesentlich zum Aufbau absolutchronologischer Zeitgerüste im Raum südlich und südöstlich der Alpen bei.The dendrochronological investigations were conducted primarily on timber from the region of Korça in the south-east of Albania. The samples come from recent trees, from churches, secular buildings, icons and from the piles of prehistoric settlements on the shore of the Great Prespa Lake and on the Macedonian side of Lake Ohrid. The majority of the 564 samples come from conifers, in particular European Black Pine (Pinus nigra), Bosnian Pine (Pinus heldreichii), fir (Abies sp.) and in prehistoric times also juniper ( Juniperus sp.). So far it has only been possible to sample wood from deciduous trees like beech (Fagus sp.) and oak (Quercus sp.) on a much smaller scale. The samples enable us to establish median series of annual growth rings from the Neolithic (6th millennium), middle Bronze Age (3rd millennium), the Middle Ages and the modern era. Absolute datings are at the moment sufficient only for timber finds from the last 1000 years. So far, 219 annual growth ring series from 36 icons and seven buildings have been dated. The contribution also discusses aspects of climate history, the history of building and art, and historical forms of forest utilization. The continuation of these investigations is contributing significantly to the development of an absolute chronological framework for the region south and south-east of the Alps

Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mnx+ oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II) glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure–property relationships. The oxidation process related to the different MnOx species was observed by in situ X-ray diffraction (XRD) measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II) glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM) and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnOx species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnOx species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species

Increased liver carcinogenesis and enrichment of stem cell properties in livers of Dickkopf 2 (Dkk2) deleted mice

Dkk2 a antagonist of the Wnt/beta-catenin-signaling pathway was shown to be silenced in diverse cancers. More recent data indicate that Dkk family members may also possess functions independent of Wnt-signaling during carcinogenesis. The detailed biological function of Dkks and its relevance for liver cancer is unknown. We analyzed the effects of a genetic deletion of Dkk2 (Dkk2(-/-)) in a hepatocarcinogenesis model using DEN/Phenobarbital. Untreated Dkk2(-/-) animals, showed considerable atypia with variation of hepatocyte size and chromatin density. In livers of Dkk2(-/-) mice nodule formation was seen at 9 months of age with focal loss of trabecular architecture and atypical hepatocytes and after DEN induction Dkk2(-/-) mice developed significantly more liver tumors compared to controls. Whole transcriptome analysis of untreated Dkk2(-/-) liver tissue revealed a Dkk2-dependent genetic network involving Wnt/beta-Catenin but also multiple additional oncogenic factors, such as e.g. Pdgf-b, Gdf-15 and Hnf4a. Dkk2(-/-) tumor cells showed a significant deregulation of stemness genes associated with enhanced colony forming properties. Integration of the Dkk2(-/-) signature into human data was strongly associated with patients survival. Dkk2 deletion results in alterations of liver morphology leading to an increased frequency of liver cancer. The associated genetic changes included factors not primarily related to Wnt/beta-Catenin-signaling and correlated with the clinical outcome of HCC-patients