Cosmology with Weak Lensing Surveys

Weak gravitational lensing surveys measure the distortion of the image of distant sources due to the deflections of light rays by the fluctuations of the gravitational potential along the line of sight. Since they probe the non-linear matter power spectrum itself at medium redshift such surveys are complimentary to both galaxy surveys (which follow stellar light) and cosmic microwave background observations (which probe the linear regime at high redshift). Ongoing CMB experiments such as WMAP and the future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM, e.g. SNAP) or the Large-aperture Synoptic Survey Telescope (LSST) will play a major role in advancing our understanding of the universe in this direction. In this review article we describe various aspects of weak lensing surveys and how they can help us in understanding our universe.Comment: 15 pages, review article to appear in 2005 Triennial Issue of Phil. Trans.

Developing a measure of socio-cultural origins for the European Social Survey

A person’s ethnic or socio-cultural background has been shown to be an important predictor of a range of social attitudes and behaviours. Ideally, therefore, we want to capture such information alongside other demographic variables in social surveys. However, gathering information about people’s socio-cultural origins as part of a cross-national survey is complicated, not least because of the need to capture complex variation in national, ethnic and other cultural groupings prevalent across countries: The socio-cultural composition of populations vastly differs across countries. The European Social Survey (ESS), a biannual survey of cross-national attitudes and opinions conducted in over 36 European countries since 2001, in 2014/15 trialled an approach to collecting data on socio-cultural origins based on a measure of respondents’ self-reported ancestry, i.e. family origins or descent. A questionnaire item was developed which involved countries fielding the item using a country -specific showcard and recoding responses into a newly developed European Standard Classification of Cultural and Ethnic Groups (ESCEG) to create harmonised variables for comparative analysis. Following a thorough evaluation of the item’s performance it has since been decided to include the ancestry item, with some modifications, as a permanent addition to the ESS core questionnaire from Round 8 (2016/17) onwards. This report summarises findings from the evaluation conducted into the development and performance of the new ancestry item in ESS Round 7 and the recommendations made for the item’s further development and deployment. It also makes some suggestions on how to code derived variables for statistical analysis. The evaluation concluded that the item worked well across ESS countries and generated meaningful data on respondents’ socio-cultural origins. There were no significant problems with implementation reported. However, the evaluation also highlighted a number of ways in which the item could be improved especially as regards adaptation for different countries. These include improved guidance on translation, revisions to the harmonised code-frame, and more consistent treatment of sub-national socio-cultural groups. This evaluation report will be of interest both to researcher’s wishing to carry out substantive analyses using the new ESS ancestry measure and survey methodologists interested in lessons learned for the development of cross-national questionnaires and classifications

Quasideuteron states with deformed core

The M1 transitions between low-lying T=1 and T=0 states in deformed odd-odd N=Z nuclei are analyzed in the frames of the rotor-plus-particle model. Using the representation of an explicit coupling of angular momenta we show that strong coupling of the quasideuteron configurations to the axially deformed core results in a distribution of the total 0+ --> 1+ strength among a few low-lying 1+ states. Simple analytical formulae for B(M1) values are derived. The realization of the M1 sum rule for the low-lying 1+,T=0 states is indicated. The calculated B(M1) values are found to be in good agreement with experimental data and reveal specific features of collectivity in odd-odd N=Z nuclei.Comment: 11 pages, 1 figure, LaTe

Integrin-mediated transactivation of P2X7R via hemichannel-dependent ATP release stimulates astrocyte migration.

Our previous reports indicate that ligand-induced αVβ3 integrin and Syndecan-4 engagement increases focal adhesion formation and migration of astrocytes. Additionally, ligated integrins trigger ATP release through unknown mechanisms, activating P2X7 receptors (P2X7R), and the uptake of Ca(2+) to promote cell adhesion. However, whether the activation of P2X7R and ATP release are required for astrocyte migration and whether αVβ3 integrin and Syndecan-4 receptors communicate with P2X7R via ATP remains unknown. Here, cells were stimulated with Thy-1, a reported αVβ3 integrin and Syndecan-4 ligand. Results obtained indicate that ATP was released by Thy-1 upon integrin engagement and required the participation of phosphatidylinositol-3-kinase (PI3K), phospholipase-C gamma (PLCγ) and inositol trisphosphate (IP3) receptors (IP3R). IP3R activation leads to increased intracellular Ca(2+), hemichannel (Connexin-43 and Pannexin-1) opening, and ATP release. Moreover, silencing of the P2X7R or addition of hemichannel blockers precluded Thy-1-induced astrocyte migration. Finally, Thy-1 lacking the integrin-binding site did not stimulate ATP release, whereas Thy-1 mutated in the Syndecan-4-binding domain increased ATP release, albeit to a lesser extent and with delayed kinetics compared to wild-type Thy-1. Thus, hemichannels activated downstream of an αVβ3 integrin-PI3K-PLCγ-IP3R pathway are responsible for Thy-1-induced, hemichannel-mediated and Syndecan-4-modulated ATP release that transactivates P2X7Rs to induce Ca(2+) entry. These findings uncover a hitherto unrecognized role for hemichannels in the regulation of astrocyte migration via P2X7R transactivation induced by integrin-mediated ATP release

Significance Of Assessment Experiences During Initial Teacher Training In Physical Education

This study investigates how students in the final semester of their teacher training program (licensure) at the Center of Physical Education and Sports (CEFD), Espírito Santo Federal University, Brazil, (re)interpret their assessment experiences, an integral component of their teacher training. It employs the narrative as a theoretical and methodological perspective, and it utilizes student portfolios, as well as focus groups and semi-structured individual interviews as inputs for data generation. Ten students in their eighth, or final, semester participated in this study. These were the total respondents to a "call for volunteers" among the 2014 graduating class. The results suggest that the students believe the assessment processes of their teaching practices in physical education are disjointed. They feel that the disciplines that allow them to review their own performance during teacher training are more efficient and play a stronger role in their education.221627

Weak gravitational lensing

In this brief review I consider the advances made in weak gravitational lensing over the last 8 years, concentrating on the large scales - cosmic shear. I outline the theoretical developments, observational status, and the challenges which cosmic shear must overcome to realise its full potential. Finally I consider the prospects for probing Dark Energy and extra-dimensional gravity theories with future experiments.Comment: 6 pages. Short version of invited review at Moriond Cosmology 200

Experimental evidence for 56Ni-core breaking from the low-spin structure of the N=Z nucleus 58Cu

Low-spin states in the odd-odd N=Z nucleus 58Cu were investigated with the 58Ni(p,n gamma)58Cu fusion evaporation reaction at the FN-tandem accelerator in Cologne. Seventeen low spin states below 3.6 MeV and 17 new transitions were observed. Ten multipole mixing ratios and 17 gamma-branching ratios were determined for the first time. New detailed spectroscopic information on the 2+,2 state, the Isobaric Analogue State (IAS) of the 2+,1,T=1 state of 58Ni, makes 58Cu the heaviest odd-odd N=Z nucleus with known B(E2;2+,T=1 --> 0+,T=1) value. The 4^+ state at 2.751 MeV, observed here for the first time, is identified as the IAS of the 4+,1,T=1 state in 58Ni. The new data are compared to full pf-shell model calculations with the novel GXPF1 residual interaction and to calculations within a pf5/2 configurational space with a residual surface delta interaction. The role of the 56Ni core excitations for the low-spin structure in 58Cu is discussed.Comment: 15 pages, 7 figures, submitted to Phys. Rev.

Extracting Vascular Networks under Physiological Constraints via Integer Programming

Abstract. We introduce an integer programming-based approach to vessel net-work extraction that enforces global physiological constraints on the vessel struc-ture and learn this prior from a high-resolution reference network. The method accounts for both image evidence and geometric relationships between vessels by formulating and solving an integer programming problem. Starting from an over-connected network, it is pruning vessel stumps and spurious connections by evaluating bifurcation angle and connectivity of the graph. We utilize a high-resolution micro computed tomography (µCT) dataset of a cerebrovascular corro-sion cast to obtain a reference network, perform experiments on micro magnetic resonance angiography (µMRA) images of mouse brains and discuss properties of the networks obtained under different tracking and pruning approaches.

Digital Quantum Simulation with Rydberg Atoms

We discuss in detail the implementation of an open-system quantum simulator with Rydberg states of neutral atoms held in an optical lattice. Our scheme allows one to realize both coherent as well as dissipative dynamics of complex spin models involving many-body interactions and constraints. The central building block of the simulation scheme is constituted by a mesoscopic Rydberg gate that permits the entanglement of several atoms in an efficient, robust and quick protocol. In addition, optical pumping on ancillary atoms provides the dissipative ingredient for engineering the coupling between the system and a tailored environment. As an illustration, we discuss how the simulator enables the simulation of coherent evolution of quantum spin models such as the two-dimensional Heisenberg model and Kitaev's toric code, which involves four-body spin interactions. We moreover show that in principle also the simulation of lattice fermions can be achieved. As an example for controlled dissipative dynamics, we discuss ground state cooling of frustration-free spin Hamiltonians.Comment: submitted to special issue "Quantum Information with Neutral Particles" of "Quantum Information Processing