Kinetic Monte Carlo simulations of oscillatory shape evolution for electromigration-driven islands

The shape evolution of two-dimensional islands under electromigration-driven periphery diffusion is studied by kinetic Monte Carlo (KMC) simulations and continuum theory. The energetics of the KMC model is adapted to the Cu(100) surface, and the continuum model is matched to the KMC model by a suitably parametrized choice of the orientation-dependent step stiffness and step atom mobility. At 700 K shape oscillations predicted by continuum theory are quantitatively verified by the KMC simulations, while at 500 K qualitative differences between the two modeling approaches are found.Comment: 7 pages, 6 figure

Do safeguarding concerns deter young people’s access to condoms? Issues about integrating sexual health services online

Condoms have been distributed freely, and regionally across England, since the ‘Teenage Pregnancy Strategy’ (Social Inclusion Unit, 1999) which highlighted England as having one of the highest rates of unplanned teenage conceptions in Western Europe. With the aim of making more accessible contraception and sex safer resources and protecting against infections, young people can obtain free condoms through selected registration and distribution points (Evans, 2005; Hadley and Evans, 2013). In 2003, England and Wales founded the National Chlamydia Screening Programme (NCSP) in response to high levels of Chlamydia trachomatis found in young people aged between 15 – 24 years (DH, 2012). Key messages for young people in the prevention of Chlamydia infection are: - Consistently use condoms during vaginal, anal or oral sex - Don’t share sex toys without washing them between use or covering with a fresh condom - Consistently use latex dams for cunnilingus (oral sex on a female) and oroanal sex (rimming) (NHS, 2013

Coping with Poorly Understood Domains: the Example of Internet Trust

The notion of trust, as required for secure operations over the Internet, is important for ascertaining the source of received messages. How can we measure the degree of trust in authenticating the source? Knowledge in the domain is not established, so knowledge engineering becomes knowledge generation rather than mere acquisition. Special techniques are required, and special features of KBS software become more important than in conventional domains. This paper generalizes from experience with Internet trust to discuss some techniques and software features that are important for poorly understood domains

Space Station evolution study

This is the Space Station Freedom (SSF) Evolution Study 1993 Final Report, performed under NASA Contract NAS8-38783, Task Order 5.1. This task examined: (1) the feasibility of launching current National Space Transportation System (NSTS) compatible logistics elements on expendable launch vehicles (ELV's) and the associated modifications, and (2) new, non-NSTS logistics elements for launch on ELV's to augment current SSF logistics capability

“Active” and “Passive” Coach Pathways: Elite Athletes’ Entry Routes Into High-Performance Coaching Roles

This study sought to analyse the lived experiences of so-called “fast-tracked” coaches from men’s association football and rugby union by seeking to understand how these individuals prepared for and then transitioned into a post-athletic coaching career. Semi-structured interviews were conducted with 13 male coaches. All participants were former elite athletes and had followed a fast-tracked pathway into their current post-athletic coaching roles. Participants were based in England and had retired from an athletic career within 12 months of being interviewed. Two general categories of “active” and “passive” coach pathways were identified for the career trajectory. Active coaches purposefully prepared for a coaching career during their athletic careers, whereas passive coaches did not. Passive coaches’ decisions to become a coach were often reactive and made after retiring from a competitive athletic career. Results indicate that only the career trajectory of passive coaches reflects a fast-track pathway. None of the active or passive coaches negotiated any formalised recruitment processes into their first post-athletic coaching roles. The suggestion is that prejudicial recruitment practices are enacted by senior club management which creates a homogenous coaching workforce. This furthers the need for greater governance of high-performance coach recruitment within England for these sports

Enhancing the comparability of costing methods: cross-country variability in the prices of non-traded inputs to health programmes

BACKGROUND: National and international policy makers have been increasing their focus on developing strategies to enable poor countries achieve the millennium development goals. This requires information on the costs of different types of health interventions and the resources needed to scale them up, either singly or in combinations. Cost data also guides decisions about the most appropriate mix of interventions in different settings, in view of the increasing, but still limited, resources available to improve health. Many cost and cost-effectiveness studies include only the costs incurred at the point of delivery to beneficiaries, omitting those incurred at other levels of the system such as administration, media, training and overall management. The few studies that have measured them directly suggest that they can sometimes account for a substantial proportion of total costs, so that their omission can result in biased estimates of the resources needed to run a programme or the relative cost-effectiveness of different choices. However, prices of different inputs used in the production of health interventions can vary substantially within a country. Basing cost estimates on a single price observation runs the risk that the results are based on an outlier observation rather than the typical costs of the input. METHODS: We first explore the determinants of the observed variation in the prices of selected "non-traded" intermediate inputs to health programmes – printed matter and media advertising, and water and electricity – accounting for variation within and across countries. We then use the estimated relationship to impute average prices for countries where limited data are available with uncertainty intervals. RESULTS: Prices vary across countries with GDP per capita and a number of determinants of supply and demand. Media and printing were inelastic with respect to GDP per capita, with a positive correlation, while the utilities had a surprisingly negative relationship. All equations had relatively good fits with the data. CONCLUSION: While the preferred option is to derive costs from a random sample of prices in each setting, this option is often not available to analysts. In this case, we suggest that the approach described in this paper could represent a better option than basing policy recommendations on results that are built on the basis of a single, or a few, price observations

Low-Cost Cryo-Light Microscopy Stage Fabrication for Correlated Light/Electron Microscopy

The coupling of cryo-light microscopy (cryo-LM) and cryo-electron microscopy (cryo-EM) poses a number of advantages for understanding cellular dynamics and ultrastructure. First, cells can be imaged in a near native environment for both techniques. Second, due to the vitrification process, samples are preserved by rapid physical immobilization rather than slow chemical fixation. Third, imaging the same sample with both cryo-LM and cryo-EM provides correlation of data from a single cell, rather than a comparison of "representative samples". While these benefits are well known from prior studies, the widespread use of correlative cryo-LM and cryo-EM remains limited due to the expense and complexity of buying or building a suitable cryogenic light microscopy stage. Here we demonstrate the assembly, and use of an inexpensive cryogenic stage that can be fabricated in any lab for less than $40 with parts found at local hardware and grocery stores. This cryo-LM stage is designed for use with reflected light microscopes that are fitted with long working distance air objectives. For correlative cryo-LM and cryo-EM studies, we adapt the use of carbon coated standard 3-mm cryo-EM grids as specimen supports. After adsorbing the sample to the grid, previously established protocols for vitrifying the sample and transferring/handling the grid are followed to permit multi-technique imaging. As a result, this setup allows any laboratory with a reflected light microscope to have access to direct correlative imaging of frozen hydrated samples

Operator Product Expansion for Exclusive Decays: B^+ ->Ds^+ e+e- and B^+ -> Ds^{*+} e+e-

The decays $B^+\to D_{s,d}^+e^+e^-$ and $B^+\to D_{s,d}^{*+}e^+e^-$ proceed through a weak and an electromagnetic interaction. This is a typical ``long distance'' process, usually difficult to compute systematically. We propose that over a large fraction of phase space a combination of an operator product and heavy quark expansions effectively turns this process into one in which the weak and electromagnetic interactions occur through a local operator. Moreover, we use heavy quark spin symmetry to relate all the local operators that appear in leading order of the operator expansion to two basic ones. We use this operator expansion to estimate the decay rates for $B^+\to D_{s,d}^{(*)+}e^+e^-$.Comment: 4 pages, 1 figure, Latex, published version in PR