ANKLE AND KNEE COORDINATION FOR SINGLE-LEGGED VERTICAL JUMPING COMPARED TO RUNNING

Similar basic movement patterns in ground reaction forces and ankle frontal plane kinematics of single-legged vertical jumping (JUMP) compared to running (RUN) have already been identified in earlier investigations. To broaden these findings, lower extremity kinematics of 25 subjects were recorded executing RUN and JUMP. Special focus was laid on the knee and ankle coordination of tibial endorotation and ankle eversion as well as on knee and ankle flexion/extension by applying a modified vector coding technique. RUN and JUMP demonstrated similar knee and ankle joint coordination patterns. However, differences in coupling angles unveiled phases, where joint coordination of ankle eversion/tibial endorotation was adjusted in JUMP. By comparing knee and ankle coordination of JUMP in healthy athletes with athletes suffering from anterior knee pain, common in sports with high jumping occurrences, key differences in execution leading to this overuse injury might be unveiled

Interference between direct ionisation and positronium formation in continuum in positron-hydrogen collisions

The fully differential cross section for positron-impact ionisation of hydrogen is calculated in a two-centre Born approximation. It is suggested that two-centre approaches to the problem should assume incoherent combination of contributions from direct ionisation of the atom and positronium formation in continuum

LES of the Cambridge Stratified Swirl Burner using a Sub-grid pdf Approach

The sub-grid scale probability density function equation is rearranged in order to separate the resolved and sub-grid-scale (sgs) contributions to the sgs mixing term. This allows modelling that is consistent with the limiting case of negligible sub-grid scale variations, a property required for applications to laboratory premixed flames. The new method is applied to the Cambridge Stratified Swirl Burner for 6 operating conditions, 2 isothermal and 4 burning, with varying degrees of swirl and mixture stratification. The simulations are performed with the Large Eddy Simulation (LES) code BOFFIN in which the modelled pdf transport equation is solved using the Eulerian stochastic field method. Eight stochastic fields are used to account for the influence of the sub-grid fluctuations and the chemistry is modelled with a reduced version of the GRI 3.0 mechanism for methane involving 19 species and 15 reaction steps. The simulated velocities for both the isothermal and burning cases show good agreement with the experimental data. The measured temperature and major species profiles are also reproduced to a good accuracy

VARIABILITY OF STRIDE FREQUENCY AND PRONATION VELOCITY DURING A 16 DAY RELAY-RUN AROUND GERMANY – A CASE STUDY

This case study analyzed stride frequency, represented by time of gait cycle (TGC), and maximum pronation velocity (MPV) for one subject running 350 km over 16 consecutive days. Data collection took place during a day-and-night team relay-race around Germany in 2008. TGC and MPV measurements were performed by a gyrometer incorporated in the subject’s running shoe and recorded by a portable data logger. For data analysis TGC and MPV velocity were determined in 25 runs for altogether 112,532 steps of the right foot. Means and standard deviations of both parameters for complete runs and for all consecutive five-minute segments within each run were calculated. Results showed an increase of TGC and a decrease of MPV within single runs. Between run comparisons across all 25 runs showed no systematic change in TGC and MPV during the relay-race. Interestingly, during the unfamiliar night-runs TGC and MPV were increased compared to day-runs, potentially caused by altered biorhythm or limited vision at night

Monolithic zirconia and digital impression: case report

The aim of this study is to present a clinical case of a full arch prosthetic rehabilitation on natural teeth, combining both digital work-flow and monolithic zirconi

Coulomb corrections to the three-body correlation function in high-energy heavy ion reactions

Starting from an asymptotically correct three-body Coulomb wave-function, we determine the effect of Coulomb final state interaction on the three-particle Bose-Einstein correlation function of similarly charged particles. We numerically estimate that the Riverside approximation is not precise enough to determine the three-body Coulomb correction factor in the correlation function, if the characteristic HBT radius parameter is 5 - 10 fm, which is the range of interest in high-energy heavy ion physics.Comment: 14 pages, 4 figure

Impact of Cage Size and Enrichment (Tube and Shelf) on Heart Rate Variability in Rats

Rats respond physiologically and behaviorally to environmental stressors. As cage conditions can be a stressor, it is important that experimental results acquired from caged rats are not confounded by these responses. This study determined the effects of cage size and cage enrichment (tube and shelf) on heart rate variability (HRV) in rats as a measure of stress. Electrocardiogram data were collected from 5 male Sprague-Dawley rats, each implanted with a radio-telemetric transducer to assess the ratio of the low to high frequency components of the HRV power spectrum (LF/HF). This ratio reflects the degree of sympathetic versus parasympathetic nervous activity and increases with decreasing HRV. Rats were housed for 3 weeks in each of the following cage conditions: small un-enriched, small enriched, large un-enriched and large enriched. Cage enrichment and/or larger cages did not significantly alter LF/HF values compared to the small, un-enriched cage condition, when considered independent of the sleep/wake cycle. However, when results were pooled for all cage conditions, LF/HF significantly increased during the wake cycle compared to the sleep cycle. Further analysis showed that this difference was only statistically significant for the un-enriched cage condition. Thus the presence of a tube and a shelf in a rodent cage can alter the diurnal rhythm of HRV in rats and this should be taken into account when designing experiments in which HRV is an outcome

Electron-impact ionization of atomic hydrogen at 2 eV above threshold

The convergent close-coupling method is applied to the calculation of fully differential cross sections for ionization of atomic hydrogen by 15.6 eV electrons. We find that even at this low energy the method is able to yield predictive results with small uncertainty. As a consequence we suspect that the experimental normalization at this energy is approximately a factor of two too high.Comment: 10 page

Magneto-optics of massive Dirac fermions in bulk Bi2Se3

We report on magneto-optical studies of Bi2Se3, a representative member of the 3D topological insulator family. Its electronic states in bulk are shown to be well described by a simple Dirac-type Hamiltonian for massive particles with only two parameters: the fundamental bandgap and the band velocity. In a magnetic field, this model implies a unique property - spin splitting equal to twice the cyclotron energy: Es = 2Ec. This explains the extensive magneto-transport studies concluding a fortuitous degeneracy of the spin and orbital split Landau levels in this material. The Es = 2Ec match differentiates the massive Dirac electrons in bulk Bi2Se3 from those in quantum electrodynamics, for which Es = Ec always holds.Comment: 5 pages, 3 figures and Supplementary materials, to be published in Physical Review Letter

Possible formulations for three-charged particles correlations in terms of Coulomb wave functions

The recent data for Bose-Einstein Correlations (BEC) of three-charged particles obtained by NA44 Collaboration have been analysed using theoretical formula with Coulomb wave functions. It has been recently proposed by Alt et al. It turns out that there are discrepancies between these data and the respective theoretical values. To resolve this problem we seek a possibly modified theoretical formulation of this problem by introducing the degree of coherence for the exchange effect due to the BEC between two-identical bosons. As a result we obtain a modified formulation for the BEC of three-charged particles showing good agreement with the data. Moreover, we investigate physical connection between our modified formulation and the core-halo model proposed by Csorgo et al. Our study indicates that the interaction region estimated by the BEC of three-charged particles in the S + Pb collisions at 200 GeV/c per nucleon is equal to about 1.5 fm~1.8 fm.Comment: 15 pages, 7 postscript figures, with addendu