Is it still "cycling"? Pedelec-commuting from a social-practice-perspective

The sales of pedelecs are currently skyrocketing in Germany and in many other places. As a low-carbon means of mobility, pedelecs have the potential to make a substantial contribution to the mobility transition. This thesis employs practice theory as proposed by Shove et al. (2012) to investigate this quickly evolving phenomenon. The analysis is based on interviews with e-bike commuters which were investigated using template analysis and exploratory memos. To obtain a broad picture the practice, a maximum variance sampling strategy was carried out in two cities that vary substantially with regard to velomobility: Wuppertal and Münster. This thesis one hand presents the first encompassing account on the practice elements which commuting by pedelec is composed of. It hence contributes to the debate about the depiction of practices. Furthermore, the thesis finds that pedelec commuting should be conceptualized as a variant of velomobility and not as a variant of motoring or as an independent practice. Yet, the elements integrated in pedelec-commuting are found to clearly differ from those of cycling, so that pedelec-commuting meets the requirements of everyday life much better than commuting on non-electrified bikes. The findings of this thesis suggest several pathways to strengthening this novel practice. The capacity of e-biking to serve mundane trips can for example be supported through the normalization of the use of weather- and transport relevant materials and competences. Deeper linkages with interacting practices from other sectors, such as an integration of cycling materials (GPS-trackers) into policing practices, can also con-tribute to this goal. With regard to research, the present work offers starting points for quantifications, for example on the relative importance of single elements as well as on the characteristics of their relations among each other or with regard to typical constellations of elements

The Weak Lensing Signal and the Clustering of BOSS Galaxies I: Measurements

A joint analysis of the clustering of galaxies and their weak gravitational lensing signal is well-suited to simultaneously constrain the galaxy-halo connection as well as the cosmological parameters by breaking the degeneracy between galaxy bias and the amplitude of clustering signal. In a series of two papers, we perform such an analysis at the highest redshift ($z\sim0.53$) in the literature using CMASS galaxies in the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey Eleventh Data Release (SDSS-III/BOSS DR11) catalog spanning 8300~deg$^2$. In this paper, we present details of the clustering and weak lensing measurements of these galaxies. We define a subsample of 400,916 CMASS galaxies based on their redshifts and stellar mass estimates so that the galaxies constitute an approximately volume-limited and similar population over the redshift range $0.47\le z\le 0.59$. We obtain a signal-to-noise ratio $S/N\simeq 56$ for the galaxy clustering measurement. We also explore the redshift and stellar mass dependence of the clustering signal. For the weak lensing measurement, we use existing deeper imaging data from the CFHTLS with publicly available shape and photometric redshift catalogs from CFHTLenS, but only in a 105~deg$^2$ area which overlaps with BOSS. This restricts the lensing measurement to only 5,084 CMASS galaxies. After careful systematic tests, we find a highly significant detection of the CMASS weak lensing signal, with total $S/N\simeq 26$. These measurements form the basis of the halo occupation distribution and cosmology analysis presented in More et al. (Paper II).Comment: 15 pages, 13 figures. Accepted for publication in the Astrophysical Journa

Influence of static electric fields on an optical ion trap

We recently reported on a proof-of-principle experiment demonstrating optical trapping of an ion in a single-beam dipole trap superimposed by a static electric potential [Nat. Photonics 4, 772--775 (2010)]. Here, we first discuss the experimental procedures focussing on the influence and consequences of the static electric potential. These potentials can easily prevent successful optical trapping, if their configuration is not chosen carefully. Afterwards, we analyse the dipole trap experiments with different analytic models, in which different approximations are applied. According to these models the experimental results agree with recoil heating as the relevant heating effect. In addition, a Monte-Carlo simulation has been developed to refine the analysis. It reveals a large impact of the static electric potential on the dipole trap experiments in general. While it supports the results of the analytic models for the parameters used in the experiments, the analytic models cease their validity for significantly different parameters. Finally, we propose technical improvements for future realizations of experiments with optically trapped ions.Comment: 16 pages, 16 figure

COMPARISON OF SDI, LEPA, AND SPRAY IRRIGATION PERFORMANCE FOR GRAIN SORGHUM

Subsurface drip irrigation (SDI), low−energy precision application (LEPA), and spray irrigation can be very efficient by minimizing water losses, but relative performance may vary for different irrigation system capacities, soils, crops, and climates. A three−year study was conducted at Bushland, Texas, in the Southern High Plains to compare SDI, LEPA, and spray irrigation for grain sorghum on a slowly permeable Pullman clay loam soil. Performance measures were grain yield, seed mass, soil water depletion, seasonal water use, water use efficiency (WUE), and irrigation water use efficiency (IWUE). Each irrigation method was compared at five irrigation levels: 0%, 25%, 50%, 75%, and 100% of crop evapotranspiration. The irrigation levels simulated varying well capacities typically found in the region and dryland conditions. In all three years, SDI had greater yield, WUE, and IWUE than other irrigation methods at the 50% irrigation level and especially at the 25% level, whereas spray outperformed SDI and LEPA at the 75% and 100% levels. Differences in seed mass, soil water depletion, and seasonal water use were usually insignificant at the 25% and 50% levels and inconsistent at the 75% and 100% levels. Performance was most sensitive to irrigation level, then year, and then irrigation method, although relative rankings of performance for each irrigation method within an irrigation level were consistent across years. For this climate and soil, SDI offers the greatest potential yield, WUE, and IWUE for grain sorghum when irrigation capacities are very low

Differential Microlensing of the Continuum and Broad Emission Lines in SDSS J0924+0219, the Most Anomalous Lensed Quasar

SDSS J0924+0219 is the most glaring example of a gravitational lens with anomalous flux ratios: optical broad-band photometry shows image D to be a factor of 12 fainter than expected for smooth lens potentials. We report spectroscopy showing that the anomaly is present in the broad emission line flux ratios as well. There are differences between the emission line and continuum flux ratios: the A/D ratio is 10 in the broad Lyman-alpha line and 19 in the associated continuum. Known variability argues for the presence of microlensing. We show that microlensing can account for both the continuum and emission line flux ratios, if the broad emission line region is comparable in size to the Einstein radii of the microlenses. Specifically, we need the half-light radius of the broad-line region to be R_BLR <~ 0.4 Rein ~ 9$ lt-days, which is small but reasonable. If the broad-line region is that large, then stars can contribute only 15-20% of the surface mass density at the positions of the images. While we cannot exclude the possibility that millilensing by dark matter substructure is present as well, we conclude that microlensing is present and sufficient to explain existing data. Under this hypothesis, the A/D flux ratio should return to a value close to unity on a time scale of years rather than millennia.Comment: accepted in ApJ; two figures have been added, and the statistical analysis has been improve