Merging White Dwarfs and Thermonuclear Supernovae

Thermonuclear supernovae result when interaction with a companion reignites nuclear fusion in a carbon-oxygen white dwarf, causing a thermonuclear runaway, a catastrophic gain in pressure, and the disintegration of the whole white dwarf. It is usually thought that fusion is reignited in near-pycnonuclear conditions when the white dwarf approaches the Chandrasekhar mass. I briefly describe two long-standing problems faced by this scenario, and our suggestion that these supernovae instead result from mergers of carbon-oxygen white dwarfs, including those that produce sub-Chandrasekhar mass remnants. I then turn to possible observational tests, in particular those that test the absence or presence of electron captures during the burning.Comment: 8 pages, 1 figures, accepted for publication in Phil. Tr. A, proc. of New windows on transients across the Universe, ed. P. O'Brien et al.; v2 includes changes following comments by the 2 referee

Mammography screening in Greece: an exploratory survey of women’s views, experiences and behaviours.

Background: Internationally, breast cancer comprises 29% of all cancer incidences. In Greece, 1,500-1,800women die annually from breast cancer out of the 4,000 who are affected. Only 5% are detected at an early diseasestage through mammography screening.Aim: This paper presents findings from a study exploring the factors that influence Greek women’smammography screening behaviour.Methodology: Data were collected in Athens-Greece, during the period March-July 2008, from individuals whowere members of six women’s associations. One hundred and eighty six questionnaires were completed and 33interviews were conducted from a sub-sample. This paper reports the findings from the questionnaire survey.Results: Participants had a variety of demographic characteristics with 85% of them having attendedmammography screening. Only 61% of them intended to continue in the future. Τhe majority of women agreedwith a number of factors which supported their decision to participate in regular mammography screening, such asdoctors’ encouragement and mammogram efficacy to detect breast cancer at an early stage, while anxiety wasidentified as a possible inhibitor to their participation.Conclusion: Women’s mammography screening behaviour and perceptions of mammography screening appearedto be positive in relation to their participation. However, the reasons as to why a large number of women indicatedthey were unlikely to go for mammography screening again is not known, and needs further investigation

Proof-of-concept engineering workflow demonstrator

When Microsoft needed a proof-of-concept implementation of bespoke engineering workflow software for their customer, BAE Systems, it called on the software engineering skills and experience of the Microsoft Institute for High Performance Computing. BAE Systems was looking into converting their in-house SOLAR software suite to run on the MS Compute Cluster Server product with 64-bit MPI support in conjunction with an extended Windows Workflow environment for use by their engineer

Microsoft institute for high performance computing

An overview of the Microsoft Institute for High Performance Computing at the University of Southampto

Lüke and power residue sequence diffusers

Conventional Schroeder diffusers have been successfully used for many years. However, their frequency range is limited by the flat plate effect that occurs when all the wells radiate in phase. This occurs at harmonics of p times the design frequency f(0), where p is the small prime that is used to generate the structure. A typical diffuser, using p=7 and f(0)=500 Hz, has an upper frequency limit of only 3.5 kHz. Achieving a first flat plate frequency above 20 kHz requires a prime equal to at least 41 and results in diffusers that are too big to be practical in most applications. This paper suggests an alternative approach using number theoretic sequences that, although short in length, are based on large integers. Two new sequences, Type-II Luke and power residue, have this desired characteristic. They are investigated using both simple models and the more exact boundary element method. The results show the flat plate effect is moved to much higher frequencies as expected. For Luke sequences at certain frequencies, redirection rather than dispersion is achieved. Modulation techniques can be used to mitigate these problems. Power residue sequences perform the best, providing good diffusion and a flat plate frequency outside the audible range

On being a mentor

This article explores issues relating to mentoring students, particularly ophthalmic nursing students. It highlights the importance of mentorship in learning in practice, which in turn is critical to students' education in a competency-based profession. It considers the factors essential in successful mentoring, including two-way feedback, and the importance of mentors understanding the nature of the psychological processes involved and how to assess students' learning and competencies. It also highlights the crucial gate-keeping role of mentors in ensuring that students are fit to practise, and the importance of nurse mentors themselves being fit to practise

A laboratory investigation of the variability of cloud reflected radiance fields

A method to determine the radiative properties of complex cloud fields was developed. A Cloud field optical simulator (CFOS) was constructed to simulate the interaction of cloud fields with visible radiation. The CFOS was verified by comparing experimental results from it with calculations performed with a Monte Carlo radiative transfer model. A software library was developed to process, reduce, and display CFOS data. The CFSOS was utilized to study the reflected radiane patterns from simulated cloud fields

A REGIONAL BAN OF ALACHLOR AND ATRAZINE IN SOUTHEASTERN MINNESOTA: THE ECONOMIC AND ENVIRONMENTAL EFFECTS

Crop Production/Industries, Environmental Economics and Policy,