Forward-scatter radiant mapping

Forward-scatter systems have been much neglected for the study of meteors and meteor streams. A great deal of this neglect stems from the complicated geometry which has made the interpretation of results difficult in the past. This no longer presents a problem because of the computer power now available. There are practical advantages in using forward-scatter in that low-power transmitters are much easier to handle than the high-power ones used in pulsed back-scatter radars. The data reduction of the CW signals is also significantly simpler. Because the forward-scatter reflection geometry increases the duration of the echoes relative to the back-scatter case, the problem of the underdense ceiling is partially alleviated. We have built a 'short hop' forward-scatter system between Ottawa and London (Ont) for which the transmitter and receiver are separated by about 500 km. With it, we are able to measure unambiguously the directions of arrival of the echoes using a 5-antenna interferometer. Morton and Jones (1982, MN, 198, 737) have shown how the echo direction distribution can be deconvolved to yield the meteor radiant distribution for back-scatter data. We have extended the technique to the forward-scatter case and present some preliminary meteor radiant distribution maps

One lumbar extension training session per week is sufficient for strength gains and reduction in pain in patients with chronic low back pain ergonomics

Chronic low back pain (CLBP) is the leading cause of absenteeism from the workplace and research into exercise interventions to address this problem is required. This study investigated training frequency for participants with CLBP. Participants either trained once a week (1 × week, n = 31), or twice a week (2 × week, n = 20) or did not (control group, n = 21). Participants were isometric strength tested in weeks 1 and 12 and trained dynamically either 1×week (80% of maximum) or 2×week (80% and 50%). The results (pre vs. post) showed significant increases in maximal strength, range of motion and reductions in pain for both training groups. Pain scores for the 1 × week and 2 × week both reached minimal clinical improvement change unlike the control group. Thus, one lumbar extension training session per week is sufficient for strength gains and reductions in pain in low back pain in CLBP patients

Using Electronic Mail. . .now and if and when

When Hal Taylor, Stan Prochaska and I had those extended conversations about moving the U.S. Department of Agriculture\u27s news dissemination systems into the new world of computer electronics, never did I have the idea that I would soon become one of the early users

The perception of comfort and fit of personal protective equipment in sport

During the design of sports equipment, the main focus is usually on physical performance attributes, neglecting key subjective factors such as feel and comfort. The personal protective equipment worn in sport is a typical example, where injury prevention has taken precedence over user comfort, but it is anticipated that with a new approach to the design process, comfort can be improved without sacrificing protection. Using cricket leg guards and taekwondo chest guards as an example, this study aimed to develop a systematic method for assessing user perceptions and incorporating them into the design process. Players perceptions of the factors that influence the comfort of cricket leg guards and taekwondo chest guards were elicited through the use of co-discovery sessions, focus groups and individual interviews, and analysed through an inductive process to produce a comfort model. The relative importance of each different comfort dimension was identified through the use of an online questionnaire utilising the analytical hierarchy process method. Through the combination of these methods, six general dimensions were identified with a weighting regarding the amount to which each one determines a user's perceived comfort. For both cricket and taekwondo, the majority of players ranked Fit as the most important factor affecting comfort. Experimental procedures were developed to objectively test the Fit of cricket leg guards, with regards to batting kinematics, running performance and contact pressure. These methods were combined with subjective assessments of leg guard performance, to determine if there was a relationship between users perceived comfort and objective test results. It was found that shot ROM and performance were not significantly affected by cricket leg guards, despite perceptions of increased restriction whilst wearing certain pads. Wearing cricket leg guards was found to significantly decrease running performance when compared to running without pads (p<0.05). In addition, it was found that the degree of impedance depended on pad design and could not solely be attributed to additional mass. These results correlated with the subjective assessment of three different leg guards, with respondents identifying the pad which had the largest influence on their running biomechanics and impeded their performance the most, as the most restrictive pad. Contact pressure under the pad and straps was also measured for four different leg guards whilst running. The results found that the top strap applied the greatest amount of pressure to the leg, especially at the point of maximum knee flexion. The peak pressure under the top strap was found to reach up to three times that of any other area of the pad. These results were reflected in the subjective assessment of the leg guards, with all nine subjects identifying the top strap as an area of discomfort for certain pads. The results also suggested there was a preference for pads with a larger more consistent contact area, as pad movement was perceived to increase when contact area variation was greater. Finally the results from this research were used to develop a product design specification (PDS) for a cricket leg guard, specifying size, mass, contact pressure and shape. The PDS was used to develop a concept design which would maximise comfort, whilst maintaining protection

Improved Monte Carlo Simulations of Massive Quarks

Motivated by the interest in top and bottom quark production processes at the LHC, we study the simulation of heavy quarks in the Herwig 7 Monte Carlo event generator. We first present a much improved treatment of heavy quarks in the dipole shower in Herwig 7 and extend the shower to handle decays of massive coloured particles. Taking advantage of these developments, we perform an in-depth study of the simulation of top quark pair production at the LHC, paying particular attention to the parton shower and matching uncertainties involved. Next we implement an algorithm in the dipole shower to include spin correlation effects. Using this algorithm we can produce accurate predictions of the angular distributions of top quark decay products in top pair production at the LHC. Following this we describe a modified version of the veto algorithm used in parton showers that enables the incorporation of weights. We show that the algorithm can be used to significantly reduce the CPU time required to evaluate the effects of scale variations in parton showers. Finally, we investigate the description of gluon splittings to heavy quark pairs in the angular-ordered and dipole parton showers in Herwig 7. While both parton showers correctly reproduce the leading-logarithmic term in the description of these splittings, we find that the effects of subleading contributions are significant