Impacts and atmospheric erosion on the early Earth

It was suggested that heating and/or vaporization of accreting carbonaceous-chondrite-type planetestimals could result in the release of their volatile components. Modeling of this process strongly suggests that substantial atmospheres/hydrospheres could develop this way. During most of the accretionary process, impact velocities generally differed from the escape velocity of the growing proto-planet because most of the collisions were between bodies in nearly matching orbits. Toward the end of accretion, however, collisions were rarer but more energetic, involving large planetestimals and higher impact velocities. Such impacts result in a net loss of atmosphere from a planet, and the cumulative effect impacts during the period of heavy bombardment might have dramatically depleted the original atmospheres. Models developed to study atmospheric erosion by impacts on Mars and the interaction of the vapor plume produced by KT impactor on Earth are applied to the case of the evolution of Earth's atmosphere

Jetting and the origin of tektites

The scientific consensus is that tektites were produced by impacts on the Earth, but the exact mechanism by impacts might form tektites is still unclear. The most widely cited mechanism is jetting, which results from the extremely high pressures generated at the intersection of two bodies whose surfaces converge obliquely at high speed. Theory of jetting for thin plates is extended to the case of the impact of the sphere onto a half-space. The calculations are done for the impact of a silicate sphere onto a silicate target for impact speeds of 15, 20, and 25 km/sec, spanning the range of reasonable impact speeds for asteroids. The angle of impact is varied from 0 to 75 deg. The mass jetted, the jet velocity, projectile fraction in the jet, azimuthal distribution of the jet, and the phase of the jetted material are calculated as functions of time. The total mass jetted and the overall mass-averages of jet velocity, etc. are also calculated

Production of impact melt in craters on Venus, Earth, and the moon

Impact craters imaged by Magellan clearly show large amounts of flow-like ejecta whose morphology suggests that the flows comprise low-viscosity material. It was suggested that this material may be either turbidity flows or very fine-grained ejecta, flows of ejecta plus magma, or impact melts. The last of these hypotheses is considered. If these flows are composed of impact melts, there is much more melt relative to the crater volume than is observed on the moon. The ANEOS equation of state program was used for dunite to estimate the shock pressures required for melting, with initial conditions appropriate for Venus, Earth, and the moon. A simple model was then developed, based on the Z-model for excavation flow and on crater scaling relations that allow to estimate the ratio of melt ejecta to total ejecta as a function of crater size on the three bodies

Melt droplet formation in energetic impacts

Impacts between rocky bodies at velocities exceeding about 15 km/sec are capable of melting or vaporizing both the impacting object and a portion of the target. Geological materials initially shocked to high pressure approach the liquid-vapor phase boundary from the liquid side as they decompress, breaking up into an expanding spray of liquid droplets. A simple theory is presented for estimating the sizes of these droplets as a function of impactor size and velocity. It is shown that these sizes are consistent with observations of microtektites and spherules found in the Cretaceous-Tertiary boundary layer, the Acraman impact structure, Archean beds in South Africa and lunar regolith. The model may also apply to the formation of chondrules

Nasal Carriage of Staphylococcus aureus in Australian (pre-clinical and clinical) Medical Students

The nasal carriage of Staphylococcus aureus in 808 Australian medical students was studied. Five groups of students experienced varying degrees of clinical exposure in a hospital environment ranging from 0 to 42 months. The overall percentage of carriers among the five groups did not vary. However, with increasing clinical exposure there was a decrease in the percentage of isolates sensitive to all antibiotics tested, and an increase in the carriage of S. aureus resistant to three or more antibiotics. No carriers of methicillin-resistant S. aureus (MRSA) were detected. The comparative rates of S. aureus carriage between female and male students varied. The relevance of medical students as nasal carriers of S. aureus in the hospital environment today is discussed

Battlezone: An examination of the physiological responses, movement demands and reproducibility of small-sided cricket games

As cricket training typically involves separate skill and conditioning sessions, this study reported on the movement demands, physiological responses and reproducibility of the demands of small-sided cricket games. Thirteen amateur, male cricket players (age: 22.8 ± 3.5 years, height: 1.78 ± 0.06 m, body mass: 78.6 ± 7.1 kg) completed two sessions of a generic small-sided cricket game, termed Battlezone; consisting of six repeat 8-over bouts. Heart rate and movement demands were continuously recorded, whilst blood lactate concentration and perceived exertion were recorded after each respective bout. Batsmen covered the greatest distance (1147 ± 175 m) and demonstrated the greatest mean movement speed (63 ± 9 m · min-1) during each bout. The majority of time (65-86%) was spent with a heart rate of between 51-85% HRmax and a blood lactate concentration of 1.1-2.0 mmol · L-1. Rating of perceived exertion ranged between 4.2-6.0. Movement demands and physiological responses did not differ between standardised sessions within respective playing positions (P > 0.05). The reliability for the majority of movement demands and physiological responses were moderate to high (CV: 5-17%; ICC: 0.48-1.00) within all playing positions. These results suggest that the physiological responses and movement characteristics of generic small-sided cricket games were consistent between sessions within respective playing positions. © 2013 Copyright Taylor and Francis Group, LLC

Garden varieties: how attractive are recommended garden plants to butterflies?

One way the public can engage in insect conservation is through wildlife gardening, including the growing of insect-friendly flowers as sources of nectar. However, plant varieties differ in the types of insects they attract. To determine which garden plants attracted which butterflies, we counted butterflies nectaring on 11 varieties of summer-flowering garden plants in a rural garden in East Sussex, UK. These plants were all from a list of 100 varieties considered attractive to British butterflies, and included the five varieties specifically listed by the UK charity Butterfly Conservation as best for summer nectar. A total of 2659 flower visits from 14 butterfly and one moth species were observed. We performed a principal components analysis which showed contrasting patterns between the species attracted to Origanum vulgare and Buddleia davidii. The “butterfly bush” Buddleia attracted many nymphalines, such as the peacock, Inachis io, but very few satyrines such as the gatekeeper, Pyronia tithonus, which mostly visited Origanum. Eupatorium cannibinum had the highest Simpson’s Diversity score of 0.75, while Buddleia and Origanum were lower, scoring 0.66 and 0.50 respectively. No one plant was good at attracting all observed butterfly species, as each attracted only a subset of the butterfly community. We conclude that to create a butterfly-friendly garden, a variety of plant species are required as nectar sources for butterflies. Furthermore, garden plant recommendations can probably benefit from being more precise as to the species of butterfly they attract

The Cannabinoid Use in Progressive Inflammatory brain Disease (CUPID) trial: a randomised double-blind placebo-controlled parallel-group multicentre trial and economic evaluation of cannabinoids to slow progression in multiple sclerosis.

This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.The Cannabinoid Use in Progressive Inflammatory brain Disease (CUPID) trial aimed to determine whether or not oral Δ(9)-tetrahydrocannabinol (Δ(9)-THC) slowed the course of progressive multiple sclerosis (MS); evaluate safety of cannabinoid administration; and, improve methods for testing treatments in progressive MS.The National Institute for Health Research Health Technology Assessment programmeMedical Research Council Efficacy and Mechanism Evaluation programmeMultiple Sclerosis SocietyMultiple Sclerosis Trus

'So wide and varied': The origins and character of British information science

This paper examines some characteristics of the ‘British School’ of information science. Three main forces driving the development of the new subject in Britain are identified: the documentation movement; special libraries; and the need for better treatment of scientific and technical information. Five characteristics which, taken together, distinguish the early British approach to information science from those adopted elsewhere are identified: its subject-based nature; its broad approach to information and information science; its status as an academic subject with a strong professional remit; its involvement with, but distinction from, information technology; and its involvement with memory institutions. Lessons are drawn for the future development of the information sciences

Standing up in Multiple Sclerosis (SUMS): Protocol for a multi-centre randomised controlled trial evaluating the clinical and cost effectiveness of a home-based self-management standing frame programme in people with progressive multiple sclerosis.

This study is funded by the NIHR Health Technology Assessment Programme (14/176/12), United Kingdom.Background:  Impaired mobility is a cardinal feature of multiple sclerosis (MS) and is rated by people with MS as their highest priority. By the secondary progressive phase, balance, mobility and physical activity levels are significantly compromised; an estimated 70% of people with secondary progressive MS fall regularly. Our ongoing research has systematically developed ‘Balance Right in MS’ (BRiMS), an innovative, manualised 13-week guided self-management programme tailored to the needs of people with MS, designed to improve safe mobility and minimise falls. Our eventual aim is to assess the clinical and cost effectiveness of BRiMS in people with secondary progressive MS by undertaking an appropriately statistically powered, multi-centre, assessor-blinded definitive, randomised controlled trial. This feasibility study will assess the acceptability of the intervention and test the achievability of running such a definitive trial. Methods/design:  This is a pragmatic multi-centre feasibility randomised controlled trial with blinded outcome assessment. Sixty ambulant people with secondary progressive MS who self-report two or more falls in the previous 6 months will be randomly allocated (1:1) to either the BRiMS programme plus usual care or to usual care alone. All participants will be assessed at baseline and followed up at 15 weeks and 27 weeks post-randomisation. The outcomes of this feasibility trial include: • Feasibility outcomes, including trial recruitment, retention and completion • Assessment of the proposed outcome measures for the anticipated definitive trial (including measures of walking, quality of life, falls, balance and activity level) • Measures of adherence to the BRiMS programme • Data to inform the economic evaluation in a future trial • Process evaluation (assessment of treatment fidelity and qualitative evaluation of participant and treating therapist experience) Discussion:  The BRiMS intervention aims to address a key concern for MS service users and providers. However, there are several uncertainties which need to be addressed prior to progressing to a full-scale trial, including acceptability of the BRiMS intervention and practicality of the trial procedures. This feasibility trial will provide important insights to resolve these uncertainties and will enable a protocol to be finalised for use in the definitive trial.Publisher PDFPeer reviewe