Catastrophic volcanism as a cause of shocked features found at the K/T boundary and in cryptoexplosion structures

The presence of quartz grains containing shock lamellae at the Cretaceous/Tertiary (K/T) boundary is viewed by many as the single most compelling evidence of meteoritic or cometary impact because there is no known endogenous mechanism for producing these features. Similarly the presence of shocked quartz, shatter cones, coesite and stishovite at cryptoexplosion structures is comonly taken as conclusive evidence of impact. However, several recent studies have cast doubt on this interpretation. It is argued that basaltic volcanism, although not normally explosive, can under exceptional circumstances produce overpressures sufficiently high to produce shock features. The exceptional circumstances include a high content of volatiles, usually CO2, and no preestablished pathway to the surface. Rapid cooling of the saturated basaltic magma can occur if it underlies a cooler more evolved magma in a chamber. Initial slow cooling and partial exsolution of the volatiles will cause the density of the basaltic magma to become less than that of the overlying magma, leading to overturning and mixing. Gas will escape the magma chamber along planar cracks once the pressure becomes sufficiently high. In the vicinity of the crack tip there is a smallscale deviatoric stress pattern which is thought to be sufficiently high to produce transient cracks along secondary axes in the quartz crystals, causing the planar features. The CO2-rich fluid inclusions which have been found along planar elements of quartz in basement rocks of the Vredefort Dome were likely to have been emplaced by such a process. If the mechanism described is capable of producing shocked features as above, it would require a reassessment of the origin of many cryptoexplosion structures as well as seriously weakening the case for an impact origin of the K/T event

Corrosion behaviour of crystalline and amorphous forms of the glass forming alloy Fe43Cr16Mo16C15B10

The corrosion behaviour of both crystalline and largely amorphous forms of the Fe-based glass forming alloy, Fe43Cr16Mo16C15B10 alloy was investigated. Two different methods were used to induce transformation to the amorphous form of the alloy: laser melting and HVOF spraying. Both methods produced largely amorphous material, however the high brittleness of the alloy makes it susceptible to cracking during laser treatment, hence this technique is not suitable for largescale application. Potentiodynamic scanning showed that in 0.5M H2SO4 and 3.5% NaCl electrolytes both amorphous forms of the alloy had better corrosion resistance (lower current densities for -200 to +1000mV SCE) compared to the crystalline material. The laser treated material and HVOF coating performed similarly in 3.5% NaCl. In 0.5M H2SO4 the HVOF coating had a lower current density than the laser melted material for almost all of the potential range -300 to +1000mV SCE. The improved corrosion behaviour of the largely amorphous material is attributed to its homogeneity, and particularly to the elimination of the Mo-rich phase that underwent preferential corrosion in the crystalline form of the material

Challenges in evaluating Welfare to Work policy interventions: Would an RCT design have been the answer to all our problems?

<p>Background: UK policy direction for recipients of unemployment and sickness benefits is to support these people into employment by increasing 'into work' interventions. Although the main aim of associated interventions is to increase levels of employment, improved health is stated as a benefit, and a driver of these interventions. This is therefore a potentially important policy intervention with respect to health and health inequalities, and needs to be validated through rigorous impact evaluation.</p> <p>We attempted to evaluate the Pathways Advisory Service intervention which aims to provide employment support for Incapacity Benefit recipients, but encountered a number of challenges and barriers to evaluation. This paper explores the issues that arose in designing a suitable evaluation of the Pathways Advisory Service.</p> <p>Discussion: The main issues that arose were that characteristics of the intervention lead to difficulties in defining a suitable comparison group; and governance restrictions such as uncertainty regarding ethical consent processes and data sharing between agencies for research. Some of these challenges threatened fundamentally to limit the validity of any experimental or quasi-experimental evaluation we could design - restricting recruitment, data collection and identification of an appropriate comparison group. Although a cluster randomised controlled trial design was ethically justified to evaluate the Pathways Advisory Service, this was not possible because the intervention was already being widely implemented. However, this would not have solved other barriers to evaluation. There is no obvious method to perform a controlled evaluation for interventions where only a small proportion of those eligible are exposed. Improved communication between policymakers and researchers, clarification of data sharing protocols and improved guidelines for ethics committees are tangible ways which may reduce the current obstacles to this and other similar evaluations of policy interventions which tackle key determinants of health.</p> <p>Summary: The evaluation of social interventions is hampered by more than their suitability to randomisation. Data sharing, participant identification and recruitment problems are common to randomised and non-randomised evaluation designs. These issues require further attention if we are to learn from current social policy.</p&gt

Upgrading a Social Media Strategy to Increase Twitter Engagement During the Spring Annual Meeting of the American Society of Regional Anesthesia and Pain Medicine.

Microblogs known as tweets are a rapid, effective method of information dissemination in health care. Although several medical specialties have described their Twitter conference experiences, Twitter-related data in the fields of anesthesiology and pain medicine are sparse. We therefore analyzed the Twitter content of 2 consecutive spring meetings of the American Society of Regional Anesthesia and Pain Medicine using publicly available online transcripts. We also examined the potential contribution of a targeted social media campaign on Twitter engagement during the conferences. The original Twitter meeting content was largely scientific in nature and created by meeting attendees, the majority of whom were nontrainee physicians. Physician trainees, however, represent an important and increasing minority of Twitter contributors. Physicians not in attendance predominantly contributed via retweeting original content, particularly picture-containing tweets, and thus increased reach to nonattendees. A social media campaign prior to meetings may help increase the reach of conference-related Twitter discussion

Two unusual silicoflagellate double skeletons

A study of silicoflagellate double skeletons revealed two unusual doublets that are illustrated and discussed here. One of these comprises two ten-sided Octactis skeletons that appear to form a doublet, but both in the same (apical) orientation. The other specimen is a double skeleton of Dictyocha that is slightly disarticulated, with a third, less robust skeleton in between. These unusual double skeletons suggest that there is much more to be learned about the formation of silicoflagellate skeletons and the reproductive processes in this protist grou

Use of a hydrological model for environmental management of the Usangu Wetlands, Tanzania

Wetlands / Rivers / Ecology / Environmental effects / Remote sensing / Hydrology / Simulation models / Water budget / Irrigated sites / Land cover / Time series analysis / Tanzania / Usangu Wetlands / Great Ruaha River