Contributions to the mixed-alkali effect in molecular dynamics simulations of alkali silicate glasses

The mixed-alkali effect on the cation dynamics in silicate glasses is analyzed via molecular dynamics simulations. Observations suggest a description of the dynamics in terms of stable sites mostly specific to one ionic species. As main contributions to the mixed--alkali slowdown longer residence times and an increased probability of correlated backjumps are identified. The slowdown is related to the limited accessibility of foreign sites. The mismatch experienced in a foreign site is stronger and more retarding for the larger ions, the smaller ions can be temporarily accommodated. Also correlations between unlike as well as like cations are demonstrated that support cooperative behavior.Comment: 10 pages, 12 figures, 1 table, revtex4, submitted to Phys. Rev.

Internal Friction and Vulnerability of Mixed Alkali Glasses

Based on a hopping model we show how the mixed alkali effect in glasses can be understood if only a small fraction c_V ofthe available sites for the mobile ions is vacant. In particular, we reproduce the peculiar behavior of the internal friction and the steep fall (''vulnerability'') of the mobility of the majority ion upon small replacements by the minority ion. The single and mixed alkali internal friction peaks are caused by ion-vacancy and ion-ion exchange processes. If c_V is small, they can become comparable in height even at small mixing ratios. The large vulnerability is explained by a trapping of vacancies induced by the minority ions. Reasonable choices of model parameters yield typical behaviors found in experiments.Comment: 4 pages, 4 figure

Low-frequency QPO from the 11 Hz accreting pulsar in Terzan 5: not frame dragging

We report on 6 RXTE observations taken during the 2010 outburst of the 11 Hz accreting pulsar IGR J17480-2446 located in the globular cluster Terzan 5. During these observations we find power spectra which resemble those seen in Z-type high-luminosity neutron star low-mass X-ray binaries, with a quasi-periodic oscillation (QPO) in the 35-50 Hz range simultaneous with a kHz QPO and broad band noise. Using well known frequency-frequency correlations, we identify the 35-50 Hz QPOs as the horizontal branch oscillations (HBO), which were previously suggested to be due to Lense-Thirring precession. As IGR J17480-2446 spins more than an order of magnitude more slowly than any of the other neutron stars where these QPOs were found, this QPO can not be explained by frame dragging. By extension, this casts doubt on the Lense-Thirring precession model for other low-frequency QPOs in neutron-star and perhaps even black-hole systems.Comment: 6 pages, 5 figures, Accepted for publication in ApJ

The adaptive problem of absent third-party punishment

Language is a uniquely human behaviour, which has presented unique adaptive problems. Prominent among these is the transmission of information that may affect an individual’s reputation. The possibility of punishment of those with a low reputation by absent third parties has created a selective pressure on human beings that is not shared by any other species. This has led to the evolution of unique cognitive structures that are capable of handling such a novel adaptive challenge. One of these, we argue, is the propositional theory of mind, which enables individuals to model, and potentially manipulate, their own reputation in the minds of other group members, by representing the beliefs that others have about the first party’s intentions and actions. Support for our theoretical model is provided by an observational study on tattling in two preschools, and an experimental study of giving under threat of gossip in a dictator game

Risk Culture, Neoclassical Economics, and Enterprise Risk Management

Financial regulators, rating agencies and many commentators have blamed weak Risk Culture for many of the large losses and financial company failures of the past decade. But their exposition regarding a strong Risk Culture only goes as far as describing a few of the risk management practices of an organization and falls far short of describing the beliefs and motivations that are at the heart of any culture. This discussion will present thinking about how the fundamental beliefs of Neo Classical Economics clash with the recommended risk practices and how the beliefs that underpin Enterprise Risk Management are fundamentally consistent with the recommended risk management practices but differ significantly from Neo Classical Economics beliefs

All on the same train, but heading in different directions

Insurance company managers are surveyed to discern their alignment with four risk attitudes predicted by Plural Rationality Theory. Each company management team is shown to contain a mix of beliefs, but not always the same mix. Since each belief is tied to a different expectation for appropriate risk management, there are inherent conflicts with a risk management culture that is tied to a single belief. The paper concludes with descriptions of hybrid risk management cultures that would have some appeal to various pairs of the four beliefs

Joining up health and bioinformatics: e-science meets e-health

CLEF (Co-operative Clinical e-Science Framework) is an MRC sponsored project in the e-Science programme that aims to establish methodologies and a technical infrastructure forthe next generation of integrated clinical and bioscience research. It is developing methodsfor managing and using pseudonymised repositories of the long-term patient histories whichcan be linked to genetic, genomic information or used to support patient care. CLEF concentrateson removing key barriers to managing such repositories ? ethical issues, informationcapture, integration of disparate sources into coherent ?chronicles? of events, userorientedmechanisms for querying and displaying the information, and compiling the requiredknowledge resources. This paper describes the overall information flow and technicalapproach designed to meet these aims within a Grid framework

Beyond the Post: Exploring Equine Operators’ Understanding and Role in Conservation Best Management Practices

The equine industry is an established part of Maryland agriculture with 79,100 equines valued at approximately $714 million in the state; approximately 10% of these animals are housed in one county. Equine operators are a unique demographic in the agricultural realm, because they are not managing land to produce food or fiber and often are employed in other professions unrelated to agriculture. These operators tend to be unaware of land conservation practices and can have a detrimental effect on areas, like the Chesapeake Bay economy and ecosystem, if shared resources are exploited. The purpose of this study was to explore equine operators’ knowledge and connection of conservation best management practices (BMPs) and their role in being a caretaker of the land. The study was informed by the diffusion of innovations theory and gathered data through semi-structured, qualitative interviews. Equine operators in the study were found to use a variety of informational sources, had a high level of adoption of the BMPs they used, and overall, a majority of participants saw their role as caretakers of the land as an important aspect of their environmental actions. Recommendations from this research include improving communication processes to increase the spread of BMPs and adjusting specific infrastructure aspects to improve retention of equine operators practicing conservation efforts. Further research should investigate other niche areas of agriculture that could potentially be struggling with a knowledge deficit of BMPs and communication neglect between conservation offices and audiences