35,423 research outputs found
The Geant4 Hadronic Verification Suite for the Cascade Energy Range
A Geant4 hadronic process verification suite has been designed to test and
optimize Geant4 hadronic models in the cascade energy range. It focuses on
quantities relevant to the LHC radiation environment and spallation source
targets. The general structure of the suite is presented, including the user
interface, stages of verification, management of experimental data, event
generation, and comparison of results to data. Verification results for the
newly released Binary cascade and Bertini cascade models are presented.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 5 pages, LaTeX, 3 eps figures. PSN
MOMT00
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The effect of atmospheric entry heating on micrometeorite volatile composition
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Separation of Q from carbon in CR meteorites during stepped combustion
Introduction: The nature of the planetary noble gas carrier (Q) in meteorites remains uncertain. It is known that it is likely to be carbonaceous, but represents only a small fraction of the total macromolecular material. Q is oxidisible with nitric and other oxidizing acids. It seems to be partly destroyed with pyridine and may have an organic structure. Previously, we have shown that during parent body thermal metamorphism Q is less affected than the majority of other carbonaceous materials. If organic matter is graphitized, as has happened in the enstatite chondrite parent bodies, Q remains unaffected. In the present study we have found that Q is also separable from the majority of carbon in type 2 and 3 CR chondrites during stepped combustion. It is possible that this is because Q has become encased within the matrix, in contrast to other carbon phases, during parent body metamorphism
Competitive swimmers modify racing start depth upon request
To expand upon recent findings showing that competitive swimmers complete significantly shallower racing starts in shallower pools, 12 more experienced and 13 less experienced swimmers were filmed underwater during completion of competitive starts. Two starts (1 routine and 1 “requested shallow”) were executed from a 0.76 m block height into water 3.66 m deep. Dependent measures were
maximum head depth, head speed at maximum head depth, and distance from the starting wall at maximum head depth. Statistical analyses yielded significant main effects (p < 0.05) for both start type and swimmer experience. Starts executed by the more experienced swimmers were deeper and faster than those executed by the less experienced swimmers. When asked to dive shallowly, maximum head depth
decreased (0.19 m) and head speed increased (0.33 ms-1) regardless of experience. The ability of all swimmers to modify start depth implies that spinal cord injuries
during competitive swimming starts are not necessarily due to an inherent inability to control the depth of the start
Block height influences the head depth of competitive racing starts
The purpose of this study was to determine whether or not starting block height has an effect on the head depth and head speed of competitive racing starts. Eleven experienced, collegiate swimmers executed competitive racing starts from three different starting heights: 0.21 m (pool deck), 0.46 m (intermediate block), and 0.76 m (standard block). One-way repeated measures ANOVA indicated that starting height had a significant effect on the maximum depth of the center of the head, head speed at maximum head depth, and distance from starting wall at maximum head depth. Racing starts from the standard block and pool deck were significantly deeper, faster, and farther at maximum head depth than starts from the intermediate block. There were no differences between depth, speed, or distance between the standard block and pool deck. We conclude that there is not a positive linear
relationship between starting depth and starting height, which means that starts do not necessarily get deeper as the starting height increases
Racing start safety: head depth and head speed during competitive starts into a water depth of 1.22 m
From the perspective of swimmer safety, there have been no quantitative 3-dimensional
studies of the underwater phase of racing starts during competition. To do
so, 471 starts were filmed during a meet with a starting depth of 1.22 m and block
height of 0.76 m. Starts were stratified according to age (8 & U, 9–10, 11–12,
13–14, and 15 & O) and stroke during the first lap (freestyle, breaststroke, and
butterfly). Dependent measures were maximum head depth, head speed at maximum
head depth, and distance from the wall at maximum head depth. For all
three variables, there were significant main effects for age, F(4, 456) = 12.53, p
< .001, F(4, 456) = 27.46, p < .001, and F(4, 456) = 54.71, p < .001, respectively,
and stroke, F(2, 456) = 16.91, p < .001, F(2, 456) = 8.45, p < .001, and F(2, 456)
= 18.15, p < .001, respectively. The older swimmers performed starts that were
deeper and faster than the younger swimmers and as a result, the older swimmers
may be at a greater risk for injury when performing starts in this pool depth
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C, N and noble gases in different pH and grain size fractions of pre-solar diamonds from Boriskino chondrite
Water depth influences the head depth of competitive racing starts
Recent research suggests that swimmers perform deeper starts in deeper water (Blitvich, McElroy, Blanksby, Clothier, & Pearson, 2000; Cornett, White, Wright, Willmott, & Stager, 2011). To provide additional information relevant to the depth adjustments swimmers make as a function of water depth and the validity of values reported in prior literature, 11 collegiate swimmers were asked to execute racing starts in three water depths (1.53 m, 2.14 m, and 3.66 m). One-way repeated measures ANOVA revealed that the maximum depth of the center of the head was significantly deeper in 3.66 m as compared to the shallower water depths. No differences due to water depth were detected in head speed at maximum head depth or in the distance from the wall at which maximum head depth occurred. We concluded that swimmers can and do make head depth adjustments as a function of water depth. Earlier research performed in deep water may provide overestimates of maximum head depth following the execution of a racing start in water depth typical of competitive venues
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