365 research outputs found
A METHOD OF MOTION ANALYSIS FOR SELF-PROPELLED AQUATIC CRAFTS
Cimematography/videography has been the method of choice for the evaluation of self-propelled aquatic craft kinematics. However, direct measurements of acceleration of this type of craft has proved to be difficult. At Dalhousie the use of acceleration data in combination with video data has facilitated the analysis of rowing and canoeing kinematics. The aim of this study is to describe the method of motion analysis currently used at Dalhousie's Sport Science Lab. Description includes a custom software program developed to divide acceleration data into individual cycles and a cubic spline to normalize the data. In addition, impulse data was calculated integrating by acceleration data using Simpson's Rule as well as the Trapezoidal Rule. A multiple low pass 2nd order Butterworth digital filter has been used successfully to smooth the acceleration data. Video data has been used to confirm that the software correctly detects these variables
AN ANALYSIS OF SELECTED KINEMATIC VARIABLES IN SCULL ROWING USING MACON AND HATCHET OARS
The Hatchet oar is now used extensively in competitive rowing because it is believed to enhance performance. There has been little research to verify this. To determine possible differences between the scull kinematics using the Hatchet and Macon oar, a 24 year old male, lightweight rower, raced 2000 m on two separate days. An 8 mm video camera and a g.analyst accelerometer collected the data. A custom software program, divided the acceleration data into individual strokes and a cubic spline standardized the stroke length. Video data confirmed that the software correctly detected stroke cycles. The acceleration data was integrated using Simpson's Rule as well as the Trapezoidal Rule. First order derivatives where determined using first and second order finite differences and impulse. Velocity data was smoothed using a multiple low pass 2nd order Butterworth digital filter. Twelve discrete measures of percentage stroke length and the value at local vertices, as well as three measures of impulse where examined using one way ANOVAs. Most of the discrete measures examined were statistically significant (
Interdisciplinary communication in the intensive care unit
Background. Patient safety research has shown poor communication among intensive care unit (ICU) nurses and doctors to be a common causal factor underlying critical incidents in intensive care. This study examines whether ICU doctors and nurses have a shared perception of interdisciplinary communication in the UK ICU. Methods. Cross-sectional survey of ICU nurses and doctors in four UK hospitals using a previously established measure of ICU interdisciplinary collaboration. Results. A sample of 48 doctors and 136 nurses (47% response rate) from four ICUs responded to the survey. Nurses and doctors were found to have differing perceptions of interdisciplinary communication, with nurses reporting lower levels of communication openness between nurses and doctors. Compared with senior doctors, trainee doctors also reported lower levels of communication openness between doctors. A regression path analysis revealed that communication openness among ICU team members predicted the degree to which individuals reported understanding their patient care goals (adjR2 = 0.17). It also showed that perceptions of the quality of unit leadership predicted open communication. Conclusions. Members of ICU teams have divergent perceptions of their communication with one another. Communication openness among team members is also associated with the degree to which they understand patient care goals. It is necessary to create an atmosphere where team members feel they can communicate openly without fear of reprisal or embarrassment
Strontium sorption and precipitation behaviour during bioreduction in nitrate impacted sediments
AbstractThe behaviour of strontium (Sr2+) during microbial reduction in nitrate impacted sediments was investigated in sediment microcosm experiments relevant to nuclear sites. Although Sr2+ is not expected to be influenced directly by redox state, bioreduction of nitrate caused reduced Sr2+ solubility due to an increase in pH during bioreduction and denitrification. Sr2+ removal was greatest in systems with the highest initial nitrate loading and consequently more alkaline conditions at the end of denitrification. After denitrification, a limited re-release of Sr2+ back into solution occurred coincident with the onset of metal (Mn(IV) and Fe(III)) reduction which caused minor pH changes in all microcosms with the exception of the bicarbonate buffered system with initial nitrate of 100mM and final pH>9. In this system ~95% of Sr2+ remained associated with the sediment throughout the progression of bioreduction. Analysis of this pH 9 system using X-ray absorption spectroscopy (XAS) and electron microscopy coupled to thermodynamic modelling showed that Sr2+ became partially incorporated within carbonate phases which were formed at higher pH. This is in contrast to all other systems where final pH was <9, here XAS analysis showed that outer sphere Sr2+ sorption predominated. These results provide novel insight into the likely environmental fate of the significant radioactive contaminant, 90Sr, during changes in sediment biogeochemistry induced by bioreduction in nitrate impacted nuclear contaminated environments
Limits on Production of Magnetic Monopoles Utilizing Samples from the DO and CDF Detectors at the Tevatron
We present 90% confidence level limits on magnetic monopole production at the
Fermilab Tevatron from three sets of samples obtained from the D0 and CDF
detectors each exposed to a proton-antiproton luminosity of
(experiment E-882). Limits are obtained for the production cross-sections and
masses for low-mass accelerator-produced pointlike Dirac monopoles trapped and
bound in material surrounding the D0 and CDF collision regions. In the absence
of a complete quantum field theory of magnetic charge, we estimate these limits
on the basis of a Drell-Yan model. These results (for magnetic charge values of
1, 2, 3, and 6 times the minimum Dirac charge) extend and improve previously
published bounds.Comment: 18 pages, 17 figures, REVTeX
Rotation measure variations for 20 millisecond pulsars
We report on variations in the mean position angle of the 20 millisecond
pulsars being observed as part of the Parkes Pulsar Timing Array (PPTA)
project. It is found that the observed variations are dominated by changes in
the Faraday rotation occurring in the Earth's ionosphere. Two ionospheric
models are used to correct for the ionospheric contribution and it is found
that one based on the International Reference Ionosphere gave the best results.
Little or no significant long-term variation in interstellar RM was found with
limits typically about 0.1 rad m yr in absolute value. In a few
cases, apparently significant RM variations over timescales of a few 100 days
or more were seen. These are unlikely to be due to localised magnetised regions
crossing the line of sight since the implied magnetic fields are too high. Most
probably they are statistical fluctuations due to random spatial and temporal
variations in the interstellar electron density and magnetic field along the
line of sight.Comment: Accepted for publication in Astrophysics & Space Scienc
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
Apolipoprotein E epsilon 4 (APOE-Δ4) genotype is associated with decreased 6-month verbal memory performance after mild traumatic brain injury
Introduction: The apolipoprotein E (APOE) Δ4 allele associates with memory impairment in neurodegenerative diseases. Its association with memory after mild traumatic brain injury (mTBI) is unclear. Methods: mTBI patients (Glasgow Coma Scale score 13â15, no neurosurgical intervention, extracranial Abbreviated Injury Scale score â€1) aged â„18 years with APOE genotyping results were extracted from the Transforming Research and Clinical Knowledge in Traumatic Brain Injury Pilot (TRACK-TBI Pilot) study. Cohorts determined by APOE-Δ4(+/â) were assessed for associations with 6-month verbal memory, measured by California Verbal Learning Test, Second Edition (CVLT-II) subscales: Immediate Recall Trials 1â5 (IRT), Short-Delay Free Recall (SDFR), Short-Delay Cued Recall (SDCR), Long-Delay F
Grain Surface Models and Data for Astrochemistry
AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of âŒ25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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