High-resolution imaging at the SOAR telescope

Bright single and binary stars were observed at the 4.1-m telescope with a fast electron-multiplication camera in the regime of partial turbulence correction by the visible-light adaptive optics system. We compare the angular resolution achieved by simple averaging of AO-corrected images (long-exposure), selection and re-centering (shift-and-add or "lucky" imaging) and speckle interferometry. The effect of partial AO correction, vibrations, and image post-processing on the attained resolution is shown. Potential usefulness of these techniques is evaluated for reaching the diffraction limit in ground-based optical imaging. Measurements of 75 binary stars obtained during these tests are given and objects of special interest are discussed. We report tentative resolution of the astrometric companion to Zeta Aqr B. A concept of advanced high-resolution camera is outlined.Comment: Accepted for publication in PASP. 14 pages, 9 figures, 2 tabl

Urban heritages: how history and housing finance matter to housing form and homeownership rates

Contemporary Western cities are not uniform but display a variety of different housing forms and tenures, both between and within countries. We distinguish three general city types in this paper: low rise, single-family dwelling cities where owner-occupation is the most prevalent tenure form; multi-dwelling building cities where tenants comprise the majority and; multi-dwelling building cities where owner occupation is the principal tenure form. We argue that historical developments beginning in the nineteenth century are crucial to understanding this diversity in urban form and tenure composition across Western cities. Our path-dependent argument is twofold. First, we claim that different housing finance institutions engendered different forms of urban development during the late-nineteenth century and had helped to establish the difference between single-family dwelling cities and multi-dwelling building cities by 1914. Second, rather than stemming from countries’ welfare systems or ‘variety of capitalism’, we argue that these historical distinctions have a significant and enduring impact on today’s urban housing forms and tenures. Our argument is supported by a unique collection of data of 1095 historical cities across 27 countries

An Experimental Analysis Of the Demand For Payday Loans

The payday loan industry is one of the fastest growing segments of the consumer financial services market in the United States. We design an environment similar to the one that payday loan customers face and then conduct a laboratory experiment to examine what effect, if any, the existence of payday loans has on individuals\u27 abilities to manage and to survive financial setbacks. Our primary objective is to examine whether access to payday loans improves or worsens the likelihood of financial survival in our experiment. We also test the degree to which people\u27s use of payday loans affects their ability to survive financially. We find that payday loans help the subjects to absorb expenditure shocks and therefore survive financially. However, subjects whose demand for payday loans exceeds a certain threshold level are at a greater risk than a corresponding subject in the treatment in which payday loans do not exist

Benzo[a]pyrene, Aflatoxine B1 and Acetaldehyde Mutational Patterns in TP53 Gene Using a Functional Assay: Relevance to Human Cancer Aetiology

Mutations in the TP53 gene are the most common alterations in human tumours. TP53 mutational patterns have sometimes been linked to carcinogen exposure. In hepatocellular carcinoma, a specific G>T transversion on codon 249 is classically described as a fingerprint of aflatoxin B1 exposure. Likewise G>T transversions in codons 157 and 158 have been related to tobacco exposure in human lung cancers. However, controversies remain about the interpretation of TP53 mutational pattern in tumours as the fingerprint of genotoxin exposure. By using a functional assay, the Functional Analysis of Separated Alleles in Yeast (FASAY), the present study depicts the mutational pattern of TP53 in normal human fibroblasts after in vitro exposure to well-known carcinogens: benzo[a]pyrene, aflatoxin B1 and acetaldehyde. These in vitro patterns of mutations were then compared to those found in human tumours by using the IARC database of TP53 mutations. The results show that the TP53 mutational patterns found in human tumours can be only partly ascribed to genotoxin exposure. A complex interplay between the functional impact of the mutations on p53 phenotype and the cancer natural history may affect these patterns. However, our results strongly support that genotoxins exposure plays a major role in the aetiology of the considered cancers

Applied physics

xv, 753 p. : il.; 28 c