Permanent-magnet atom chips for the study of long, thin atom clouds

Atom-chip technology can be used to confine atoms tightly using permanently magnetised videotape along with external magnetic fields. The one-dimensional (1D) gas regime can be realised and studied by trapping the atoms in high-aspect-ratio traps in which the radial motion of the system is confined to zero-point oscillation

The effects of shoe temperature on the kinetics and kinematics of running

The aim of the current investigation was to examine the effects of cooled footwear on the kinetics and kinematics of running in comparison to footwear at normal temperature. Twelve participants ran at 4.0 m/s ± 5% in both cooled and normal temperature footwear conditions over a force platform. Two identical footwear were worn, one of which was cooled for 30 min. Lower extremity kinematics were obtained using a motion capture system and tibial accelerations were measured using a triaxial accelerometer. Differences between cooled and normal footwear temperatures were contrasted using paired samples t-tests. The results showed that midsole temperature (cooled = 4.21 °C and normal = 23.25 °C) and maximal midsole deformation during stance (cooled = 12.85 mm and normal = 14.52 mm) were significantly reduced in the cooled footwear. In addition, instantaneous loading rate (cooled = 186.21 B.W/s and normal = 167.08 B W/s), peak tibial acceleration (cooled = 12.75 g and normal = 10.70 g) and tibial acceleration slope (cooled = 478.69 g/s and normal = 327.48 g/s) were significantly greater in the cooled footwear. Finally, peak eversion (cooled = −10.57 ° and normal = −7.83°) and tibial internal rotation (cooled = 10.67 ° and normal = 7.77°) were also shown to be significantly larger in the cooled footwear condition. This study indicates that running in cooled footwear may place runners at increased risk from the biomechanical parameters linked to the aetiology of injuries

Colour Coherence in Photon Induced Reactions

Colour coherence in hard photoproduction is considered using the Monte Carlo event generators PYTHIA and HERWIG. Significant effects in the parton shower are found using multijet observables for direct and resolved photon induced reactions. The particle flow in the interjet region of direct processes shows a strong influence of string fragmentation effects.Comment: 6 pages, LaTeX, 6 eps figures included, to appear in the proceedings of the workshop "Future Physics at HERA

Automatic focus control for facsimile cameras

An electronic circuit for controlling the focus of facsimile cameras is described. The circuit consists of balanced a.c. amplifiers, two square law function generators, and a differential amplifier and power drive. The invention includes a method for maintaining the imaging sensor at the expected location of the focal plane as the facsimile camera scans a scene or terrain. A block diagram of the electronic circuitry is provided

Bose-Einstein Condensation on a Permanent-Magnet Atom Chip

We have produced a Bose-Einstein condensate on a permanent-magnet atom chip based on periodically magnetized videotape. We observe the expansion and dynamics of the condensate in one of the microscopic waveguides close to the surface. The lifetime for atoms to remain trapped near this dielectric material is significantly longer than above a metal surface of the same thickness. These results illustrate the suitability of microscopic permanent-magnet structures for quantum-coherent preparation and manipulation of cold atoms.Comment: 4 pages, 6 figures, Published in Phys. Rev. A, Rapid Com

Bose-Einstein Condensation on a Permanent-Magnet Atom Chip

We have produced a Bose-Einstein condensate on a permanent-magnet atom chip based on periodically magnetized videotape. We observe the expansion and dynamics of the condensate in one of the microscopic waveguides close to the surface. The lifetime for atoms to remain trapped near this dielectric material is significantly longer than above a metal surface of the same thickness. These results illustrate the suitability of microscopic permanent-magnet structures for quantum-coherent preparation and manipulation of cold atoms.Comment: 4 pages, 6 figures, Published in Phys. Rev. A, Rapid Com

Influence of surface on impact shock experienced during a fencing lunge

The purpose of this study was to investigate the effect of sports surface on the magnitude of impact shock experienced during a lunge movement. Thirteen experienced, competitive fencers (age 32.4 +/- 4.6 years; Height 178.4 +/- 7.2 cm; Mass 74.4 +/- 9.1 kg) performed ten lunges on four different surfaces: concrete with an overlaid vinyl layer (COVL); wooden sprung court surface (WSCS); metallic carpet fencing piste overlaid on the WSCS and: aluminium fencing piste overlaid on the WSCS. An accelerometer measured accelerations along the longitudinal axis of the tibia at 1000Hz. The results identified a significantly (P < 0.05) larger impact shock magnitude was experienced during a lunge on the COVL (14.88 +/- 8.45g) compared to the WSCS (11.61 +/- 7.30g), WSCS with metallic carpet piste (11.14 +/- 6.38g) and WSCS with aluminium piste (11.95 +/- 7.21g). Furthermore, the two types of piste used had no significant effect the impact shock magnitude measured when overlaid on the WSCS compared to the WSCS on its own. The results of this investigation suggest that occurrences of injuries related to increased levels of impact shock, may be reduced through the utilization of a WSCS as opposed to a COVL surface, during fencing participation

The influence of different force and pressure measuring transducers on lower extremity kinematics measured during walking

The examination of synchronous three dimensional (3-D) kinetics and kinematics of walking in laboratory based analyses typically requires participants/patients to make foot contact with a force or pressure measuring device. However it has been proposed that this may lead to targeting whereby participants modify their natural gait pattern in order to ensure contact with the device. This study aimed to determine the extent to which an embedded force plate (EFP) and two different pressure mats PMs affect natural gait kinematics. Male participants (n=12, age 24.23 SD 4.22 y, height 1.74m SD 0.10, mass 75.78 SD 6.90kg) walked at a velocity of 1.25 m.s-1 along a 22m walkway in four different conditions. 1. EFP, 2. FootScan (FS) PM, 3.Matscan (MS) PM, 4.No device (ND). 3-D angular kinematic parameters were collected using an eight camera motion analysis system.Differences in kinematics were examined using repeated measures ANOVAs. Significant differences were observed in hip abduction, knee flexion/extension and knee abduction between various conditions and may warrant consideration in future research. No significant differences were reported at the ankle joint in any conditions. Comparing the PMs no significant differences were observed, however significant differences between the MS and the EFP and ND conditions were identified. The research supports the efficacy of collecting gait kinematics at the ankle joint and in most variables measured at the knee and hip joints

A comparison of center of pressure variables recorded during running in barefoot, minimalist footwear, and traditional running shoes in the female population

In recent years, barefoot running and running in minimalist footwear as opposed to running in traditional running shoes has increased in popularity. The influence of such footwear choices on center of pressure (COP) displacements and velocity variables linked to injuries is yet to be understood. The aim of this study was to investigate differences between COP variables, linked to injuries measured in barefoot running, a minimalist running shoe, and with traditional running shoes and conditions during running in a healthy female population. Seventeen healthy female participants were examined. Participants performed five footfalls in each footwear condition while running at 12km/h±10% over a pressure plate while COP variables were recorded at 500Hz. The results suggest that minimalist running shoe COP characteristics were similar to those of barefoot runners, with various significant differences reported in both groups compared to runners with the traditional running shoe

The RHMC algorithm for theories with unknown spectral bounds

The Rational Hybrid Monte Carlo (RHMC) algorithm extends the Hybrid Monte Carlo algorithm for lattice QCD simulations to situations involving fractional powers of the determinant of the quadratic Dirac operator. This avoids the updating increment ($dt$) dependence of observables which plagues the Hybrid Molecular-dynamics (HMD) method. The RHMC algorithm uses rational approximations to fractional powers of the quadratic Dirac operator. Such approximations are only available when positive upper and lower bounds to the operator's spectrum are known. We apply the RHMC algorithm to simulations of 2 theories for which a positive lower spectral bound is unknown: lattice QCD with staggered quarks at finite isospin chemical potential and lattice QCD with massless staggered quarks and chiral 4-fermion interactions ($\chi$QCD). A choice of lower bound is made in each case, and the properties of the RHMC simulations these define are studied. Justification of our choices of lower bounds is made by comparing measurements with those from HMD simulations, and by comparing different choices of lower bounds.Comment: Latex(Revtex 4) 25 pages, 8 postscript figure