Response by Bivard et al to letter regarding article, "Impact of Computed Tomography Perfusion Imaging on the Response to Tenecteplase in Ischemic Stroke: Analysis of 2 Randomized Controlled Trials"

No abstract available

Social interactions in massively multiplayer online role-playing gamers

To date, most research into massively multiplayer online role-playing games (MMORPGs) has examined the demographics of play. This study explored the social interactions that occur both within and outside of MMORPGs. The sample consisted of 912 self-selected MMORPG players from 45 countries. MMORPGs were found to be highly socially interactive environments providing the opportunity to create strong friendships and emotional relationships. The study demonstrated that the social interactions in online gaming form a considerable element in the enjoyment of playing. The study showed MMORPGs can be extremely social games, with high percentages of gamers making life-long friends and partners. It was concluded that virtual gaming may allow players to express themselves in ways they may not feel comfortable doing in real life because of their appearance, gender, sexuality, and/or age. MMORPGs also offer a place where teamwork, encouragement, and fun can be experienced

Re-targetable tools and methodologies for the efficient deployment of high-level source code on coarse-grained dynamically reconfigurable architectures

Reconfigurable computing traditionally consists of a data path machine (such as an FPGA) acting as a co-processor to a conventional microprocessor. This involves partitioning the application such that the data path intensive parts are implemented on the reconfigurable fabric, and the control flow intensive parts are implemented on the microprocessor. Often the two parts have to be written in different languages. New highly parallel data path architectures allow parallelism approaching that of FPGAs, but are able to be reconfigured very rapidly. As a result, it is possible to use these architectures to perform control flow in a manner similar to a microprocessor, and thus a complete program can be described from an unmodified high-level language (in particular C). This overcomes the historical instruction-level parallelism (ILP) wall.To make full use of the available parallelism , existing microprocessor tool flows are insufficient. Data path machines are typically programmed via HDL tools from the ASIC design world. This expresses algorithm s at a low er level than the application algorithm s are typically developed in. The work in this thesis builds upon earlier work to allow applications to be described from high-level languages, by employing low-level optimisations in the compiler back-end and working from the assembly, to maximise parallel efficiency. This consists of scheduling, where known techniques are used to pack instructions into basic blocks that map well to the reconfigurable core (optimising spatial efficiency); then automatic pipelining is applied to dramatically improve the achievable throughput (optimising temporal efficiency). Together these can be thought of as “instruction-level parallelism done right”. Speed-ups of more than an order of magnitude were achieved, yielding throughputs of 180-380M Pixels/s on typical image signal processing tasks, matching the performance of hard-wired ASICs.Furthermore, conventional software-based simulation technologies for data path machines are too slow for use in application verification. This thesis demonstrates how a high-speed software emulator can be created for self-controlled dynamically reconfigurable data path machines, using a static serialisation of the data paths in each configuration context. This yields run-time performance several orders of magnitude higher than existing techniques, making it suitable for use in feedback-directed optimisation

A study of the altitude dependence of the large cosmic-ray showers

Assuming primary electrons, the theoretical variation of shower counting rate with altitude has been computed and a comparison made with the observations of Kraybill. Expressed as the ratio to sea level, the observed counting rate has a maximum of 63 as compared to 24 for the theoretical curve. The observed maximum is near 27,000 feet while the computed maximum is at 22,000 feet. Approximations in the calculation and observational uncertainties may make this difference in the elevations of the maxima spurious. The approximations are such as to give too low a theoretical counting rate, but an estimate of the magnitude seems to leave the theoretical maximum counting rate too small by a factor of 1.5 to 2. A computation based upon a mechanism for the multiple production of secondaries by primary protons, which has been proposed by Lewis, Oppenheimer and Wouthuysen, would probably lead to better agreement with the observations. The zenith angle distribution of showers detected by Kraybill’s counters at 30,000 feet has been computed and compared with one determined by Mr. E.W. Cowan from cloud chamber measurements. The theoretical distribution is twice as broad as the observed one. The angular distribution inferred from the altitude dependence observed by Kraybill is in much better agreement with the theoretical than with the cloud chamber distribution. The discrepancy of the cloud chamber observations may arise from the fact that it was only possible to assign a direction to the tracks in 20 to 30 per cent of the photographs.</p

Two-harmonic approximation for gravitational waveforms from precessing binaries

Binary-black-hole orbits precess when the black-hole spins are mis-aligned with the binary's orbital angular momentum. The apparently complicated dynamics can in most cases be described as simple precession of the orbital angular momentum about an approximately fixed total angular momentum. However, the imprint of the precession on the observed gravitational-wave signal is yet more complicated, with a non-trivial time-varying dependence on black-hole dynamics, the binary's orientation and the detector polarization. As a result, it is difficult to predict under which conditions precession effects are measurable in gravitational-wave observations, and their impact on both signal detection and source characterization. We show that the observed waveform can be simplified by decomposing it as a power series in a new precession parameter $b = \tan(\beta/2)$, where $\beta$ is the opening angle between the orbital and total angular momenta. The power series is made up of five harmonics, with frequencies that differ by the binary's precession frequency, and individually do not exhibit amplitude and phase modulations. In many cases, the waveform can be well approximated by the two leading harmonics. In this approximation we are able to obtain a simple picture of precession as caused by the beating of two waveforms of similar frequency. This enables us to identify regions of the parameter space where precession is likely to have an observable effect on the waveform, and to propose a new approach to searching for signals from precessing binaries, based upon the two-harmonic approximation.Comment: 23 pages, 9 figures. Accepted for publication in PR

Assessing the impacts of the first year of rotavirus vaccination in the United Kingdom

The United Kingdom (UK) added rotavirus (RV) vaccine (Rotarix GlaxoSmithKline) to the national vaccine schedule in July 2013. During the 2012–2014 rotavirus seasons, children presenting to the Bristol Royal Hospital for Children Emergency Department with gastroenteritis symptoms had stool virology analysis (real-time PCR) and clinical outcome recorded. Nosocomial cases were identified as patients with non-gastroenteritis diagnosis testing positive for rotavirus &gt; 48h after admission. In comparison to average pre-vaccine seasons, in the first year after vaccine introduction there were 48% fewer attendances diagnosed with gastroenteritis, 53% reduction in gastroenteritis admissions and a total saving of 330 bed-days occupancy. There was an overall reduction in number of rotavirus-positive stool samples with 94% reduction in children aged under one year and a 65% reduction in those too old to have been vaccinated. In the first year after the introduction of universal vaccination against rotavirus we observed a profound reduction in gastroenteritis presentations and admissions with a substantial possible herd effect seen in older children. Extrapolating these findings to the UK population we estimate secondary healthcare savings in the first year of ca £7.5 (€10.5) million. Ongoing surveillance will be required to determine the long-term impact of the RV immunisation programme

Factors influencing community case management and care hours for clients with traumatic brain injury living in the UK

Objective: To investigate the relationship between deficits associated with traumatic brain injury (TBI) and case management (CM) and care/support (CS) in two UK community samples. Research design: Prospective descriptive study. Method: Case managers across the UK and from a single UK CM service contributed client profiles to two data sets (Groups 1 and 2, respectively). Data were entered on demographics, injury severity, functional skills, functional-cognition (including executive functions), behaviour and CM and CS hours. Relationships were explored between areas of disability and service provision. Results: Clients in Group 2 were more severely injured, longer post-injury and had less family support than clients in Group 1. There were few significant differences between Groups 1 and 2 on measures of Functionalskill, Functional-cognition and Behaviour disorder. Deficits in Functionalskills were associated with CS, but not CM. Deficits in measures of executive functions (impulsivity, predictability, response to direction) were related to CM, but not to CS. Insight was related to both CM and CS. Variables related to behaviour disorder were related to CM, but were less often correlated to CS. Conclusions: The need for community support is related not only to Functionalskills (CS), but also to behaviour disorder, self-regulatory skills and impaired insight (CM)

PCB's and other organochlorine contaminants in white whales (Delphinapterus leucas) from West Greenland: variations with age and sex

Blubber samples from 138 white whales from two locations in West Greenland (the Nuussuaq area, ea. 74°N, 58°W, and the Disko Bugt area, ea. 69°N, 53°W and skin and kidney samples from 20 white whales from Nuussuaq were analysed for PCB congeners and related organochlorines (hexachlorohexanes (ΣHCH), chlorinated bornanes (ΣCHB), chlordane (ΣCHLORD), DDT-related compounds (ΣDDT), dieldrin and mirex). The large sample size permitted a detailed assessment of the variation of contaminant levels with age and sex. Mean concentrations of all major organochlorine (OC) groups (ΣPCB, lDDT, ΣCHLORD, ΣCHB) were not significantly different between the Nuussuaq and Disko Bugt groups. After an age of 5.5 years, a consistent decline in concentration levels of all four major OC's was observed in females. In contrast, only marginal differences in ΣPCB, ΣCHB and ΣCHLORD concentrations and a substantial increase in ΣDDT were observed in males. The observed decline in females occurred near the age of attainment of sexual maturity and preceding commencement of lactation. Residue levels in sexually immature animals (male and female) and male-female differences in mean concentrations of ΣPCB and p,p' -ODE in adult animals are consistent with a lactation period of less than one year. Young animals could be distinguished from adults, using principal component analysis, by higher proportions of lower chlorinated PCB's and more water soluble OC's such as p,p'-DDE which are preferentially transferred during lactation