Dark Radiation from a hidden U(1)

We discuss the impact of a hidden sector consisting of Minicharged Particles (MCPs) and massless hidden photons on the expansion history of our Universe. We present parameter scans for the amount of extra relativistic particles (Neff) and the abundance of light nuclei for fermionic MCPs with masses between ~100 keV and 10 GeV and minicharges in the range 10^(-11)-1. Current CMB and BBN data significantly constrain the available parameter space of MCPs. The shown results are a valuable indicator for future experimental searches and are presented in a flexible way so that more accurate results on Neff can be easily interpreted.Comment: Contributed to the 10th Patras Workshop on Axions, WIMPs and WISPs, CERN, June 29 to July 4, 201

The sediment record of Lake Ohrid (Albania/Macedonia) � new methodological approaches, tephrostratigraphy, chronology, and inferences of past climatic and environmental changes

This thesis had two primary objectives: One objective was to explore and develop applications of Fourier transform infrared spectroscopy (FTIRS) for the quantification of biogeochemical properties in lake sediment; the other objective was to assess the Lake Ohrid (Albania/Macedonia) sediment record with an emphasis on tephrostratigraphy and inferences of climatic and environmental changes using a 15 m long sediment succession (core Co1202) from the north-eastern part of the lake. Studies presented in this thesis were conducted within the scope of an envisaged deep drilling campaign at Lake Ohrid and therefore represent important preliminary studies. FTIR spectra of lacustrine sediment samples were calibrated to infer concentrations of total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), and biogenic silica (BSi). To test the applicability of the FTIRS technique, site-specific FTIRS calibrations and FTIRS calibrations based on a surface sediment dataset from 94 northern Swedish lakes were constructed. Both approaches demonstrated significant correlations between FTIRS-inferred and conventionally assessed biogeochemical property concentrations, ranging between R2 = 0.79 � 0.99 for TOC, R2 = 0.85 � 0.99 for TIC, R2 = 0.62 � 0.84 for TN, and R2 = 0.68 � 0.94 for BSi. These results, in combination with the small amount of sample material (0.01 g) required, negligible sample pre-treatments, and low costs of analysis, show that FTIRS is a promising analytical alternative to infer biogeochemical properties, especially when large sample quantities need to be analysed. The finding of ten tephra and cryptotephra layers throughout the Co1202 sediment succession and their correlation with explosive eruptions of Italian volcanoes provided new data on the dispersal of ash originating from these eruptions. The relatively well-known ages of these tephra and cryptotephra layers combined with seven radiocarbon dates, enabled a chronological framework for core Co1202 to be established. Based on these chronological constrains, the Co1202 succession covers the last glacial-interglacial cycle back to 136 ka, except for a hiatus between 97.6 and 81.7 ka. Assessment of climatic and environmental changes using lithological, sedimentological, geochemical, and physical indicators revealed that Lake Ohrid´s sediments sensitively recorded both long- and short-term climatic fluctuations over the past 136 kyrs. Despite some minor discrepancies, the climate fluctuations documented in the Lake Ohrid sediment record are well correlated with other climate records in the wider Mediterranean region. These studies emphasise the potential of Lake Ohrid as a valuable archive of dispersed volcanic products from Italian volcanoes and for climatic and environmental changes in the northern-central Mediterranean region

new methodological approaches, tephrostratigraphy, chronology, and inferences of past climatic and environmental changes

This thesis had two primary objectives: One objective was to explore and develop applications of Fourier transform infrared spectroscopy (FTIRS) for the quantification of biogeochemical properties in lake sediment; the other objective was to assess the Lake Ohrid (Albania/Macedonia) sediment record with an emphasis on tephrostratigraphy and inferences of climatic and environmental changes using a 15 m long sediment succession (core Co1202) from the north-eastern part of the lake. Studies presented in this thesis were conducted within the scope of an envisaged deep drilling campaign at Lake Ohrid and therefore represent important preliminary studies. FTIR spectra of lacustrine sediment samples were calibrated to infer concentrations of total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), and biogenic silica (BSi). To test the applicability of the FTIRS technique, site-specific FTIRS calibrations and FTIRS calibrations based on a surface sediment dataset from 94 northern Swedish lakes were constructed. Both approaches demonstrated significant correlations between FTIRS-inferred and conventionally assessed biogeochemical property concentrations, ranging between R2 = 0.79 0.99 for TOC, R2 = 0.85 0.99 for TIC, R2 = 0.62 0.84 for TN, and R2 = 0.68 0.94 for BSi ...Zsfassung in dt. und engl. Sprachethesi

The transfer of family businesses in Northern Germany and Austria

The transfer of family businesses from one generation to the next can be considered as an event with far-reaching effects for the business. Investments and decisions about restructuring the business are closely tied to succession considerations. This paper analyzes successions plans in the primary sector using a survey conducted in 2003 of 348 farmers in Schleswig-Holstein (Northern Germany) and 278 farmers in Austria. Three samples were obtained: full time farmers in Schleswig-Holstein, full time farmers in Austria and part time farmers in Austria. The structure of the farm sector in both countries differs in several ways: Farmers in Schleswig-Holstein operate on larger scales, are more market oriented and use more intensive production technologies than their Austrian counterparts. In addition, Austrian farmers have distinct traditional attitudes in farming and are likely located in disadvantaged areas on average. The analysis focuses on differences in succession plans and farm family characteristics in the three samples. This encompasses the fact that farms in Schleswig-Holstein have proportionally higher rates of identified successors and farm adjustment plans than in Austria. Results also show that there are not only significant differences in farm succession patterns, but also in value systems. --

The influence of bulk evolution models on heavy-quark phenomenology

We study the impact of different Quark-Gluon Plasma expansion scenarios in heavy-ion collisions on spectra and elliptic flow of heavy quarks. For identical heavy-quark transport coefficients relativistic Langevin simulations with different expansion scenarios can lead to appreciable variations in the calculated suppression and elliptic flow of the heavy-quark spectra, by up to a factor of two. A cross comparison with two sets of transport coefficients supports these findings, illustrating the importance of realistic expansion models for quantitative evaluations of heavy-quark observables in heavy-ion collisions. It also turns out that differences in freeze-out prescriptions and Langevin realizations play a significant role in these variations. Light-quark observables are essential in reducing the uncertainties associated with the bulk-matter evolution, even though uncertainties due to the freeze-out prescription persist.Comment: submitted to Physical Review