A prospective study of the incidence and nature of injuries to adult rugby players.

The incidence and nature of injuries occurring in 8 adult club rugby teams was followed prospectively during the 1988 rugby season. The findings were compared with those from two similar studies in schoolboy rugby players. A total of 114 injuries were sustained by 78 players; 85% of injuries occurred during matches. Injury was most prevalent during the first 8 weeks of the season and again after the mid-season break. Hookers (19%), wings (15%), fullbacks (11%) and centres (10%) were the players most often injured. Injury occurred most commonly when the player was tackled (26%), during open play (21%) and during the loose scrum 17%). Muscles (33%) and ligaments (32%) were the anatomical strutures most often injured. Injury caused 35% of injured players to miss more than 35 days of rugby. Thirteen percent of injured players did not play again for the rest of the season and only 14% of injured players returned to rugby after 7 days or less. Prolonged disability was associated with ligament injuries (57%), dislocations (17%) and fractures (10%)

Magnetic Ordering and Superconductivity in the RE2_2Ir3_3Ge5_5 (RE = Y, La-Tm, Lu) System

We find that the compounds for RE = Y, La-Dy, crystallize in the tetragonal Ibam (U$_2$Co$_3$Si$_5$ type) structure whereas the compounds for RE = Er-Lu, crystallize in a new orthorhombic structure with a space group Pmmn. Samples of Ho$_2$Ir$_3$Ge$_5$ were always found to be multiphase. The compounds for RE = Y to Dy which adopt the Ibam type structure show a metallic resistivity whereas the compounds with RE = Er, Tm and Lu show an anomalous behavior in the resistivity with a semiconducting increase in $\rho$ as we go down in temperature from 300K. Interestingly we had earlier found a positive temperature coefficient of resistivity for the Yb sample in the same temperature range. We will compare this behavior with similar observations in the compounds RE$_3$Ru$_4$Ge$_{13}$ and REBiPt. La$_2$Ir$_3$Ge$_5$ and Y$_2$Ir$_3$Ge$_5$ show bulk superconductivity below 1.8K and 2.5K respectively. Our results confirm that Ce$_2$Ir$_3$Ge$_5$ shows a Kondo lattice behavior and undergoes antiferromagnetic ordering below 8.5K. Most of the other compounds containing magnetic rare-earth elements undergo a single antiferromagnetic transition at low temperatures (T$\leq$12K) while Gd$_2$Ir$_3$Ge$_5$, Dy$_2$Ir$_3$Ge$_5$ and Nd$_2$Ir$_3$Ge$_5$ show multiple transitions. The T$_N$'s for most of the compounds roughly scale with the de Gennes factor. which suggests that the chief mechanism of interaction leading to the magnetic ordering of the magnetic moments may be the RKKY interaction.Comment: 25 pages, 16 figure

Melting and Dimensionality of the Vortex Lattice in Underdoped YBa2Cu3O6.60

Muon spin rotation measurements of the magnetic field distribution in the vortex state of the oxygen deficient high-Tc superconductor YBa{2}Cu{3}O{6.60} reveal a vortex-lattice melting transition at much lower temperature than that in the fully oxygenated material. The transition is best described by a model in which adjacent layers of ``pancake'' vortices decouple in the liquid phase. Evidence is also found for a pinning-induced crossover from a solid 3D to quasi-2D vortex lattice, similar to that observed in the highly anisotropic superconductor Bi{2+x}Sr{2-x}CaCu{2}O{8+y}.Comment: 8 pages, 4 figures, 5 postscript file

Energy Distribution in f(R) Gravity

The well-known energy problem is discussed in f(R) theory of gravity. We use the generalized Landau-Lifshitz energy-momentum complex in the framework of metric f(R) gravity to evaluate the energy density of plane symmetric solutions for some general f(R) models. In particular, this quantity is found for some popular choices of f(R) models. The constant scalar curvature condition and the stability condition for these models are also discussed. Further, we investigate the energy distribution of cosmic string spacetime.Comment: 15 pages, accepted for publication in Gen. Relativ. & Gra

Spin fluctuations in nearly magnetic metals from ab-initio dynamical spin susceptibility calculations:application to Pd and Cr95V5

We describe our theoretical formalism and computational scheme for making ab-initio calculations of the dynamic paramagnetic spin susceptibilities of metals and alloys at finite temperatures. Its basis is Time-Dependent Density Functional Theory within an electronic multiple scattering, imaginary time Green function formalism. Results receive a natural interpretation in terms of overdamped oscillator systems making them suitable for incorporation into spin fluctuation theories. For illustration we apply our method to the nearly ferromagnetic metal Pd and the nearly antiferromagnetic chromium alloy Cr95V5. We compare and contrast the spin dynamics of these two metals and in each case identify those fluctuations with relaxation times much longer than typical electronic `hopping times'Comment: 21 pages, 9 figures. To appear in Physical Review B (July 2000

Characterization of superconducting and magnetic materials with muon spin rotation and neutron scattering. Progress report, March 1996--August 1997 and final report, June 1988--August 1997

This report represents the culmination of over nine years of research activity in the study of superconducting and magnetically ordered materials using the muon spin rotation ({mu}SR) and neutron scattering techniques. Because all the activities that took place up until March 1996 have been covered in previous annual reports, this final report includes only a brief overview of activities prior to that date, and concentrates on the period from March 1996 through August 1997. The primary activity undertaken in this project has been studies of high-temperature superconductors and their close chemical relatives with the {mu}SR technique. These experiments extend from early work done with a relatively primitive muon beam at the AGS of Brookhaven National Laboratory and large polycrystalline samples of the earliest known high-{Tc} materials to studies of very small high-purity single crystals of the best high-{Tc} materials currently available using the highest quality surface muon beams and specially-designed low-background spectrometers at the Tri-University Meson Facility (TRIUMF) in the past three years. During the period since the last annual report five {mu}SR experiments were done at TRIUMF with DOE support. A study of single-crystal high-temperature superconductors was done in July 1996. A study of the quasicrystal materials Gd{sub 8}Mg{sub 42}Zn{sub 50} and Tb{sub 8}Mg{sub 42}Zn{sub 50} was done by D.R. Noakes in collaboration with G.M. Kalvius of the Technical University of Munich and R. Waeppling of Uppsala University during the first week of December 1996. During the second week of December 1996 a study of the cryocrystals CH{sub 4} and CF{sub 4} was done by D.R. Noakes in collaboration with S. Storchak of Moscow State University and J.H. Brewer of the University of British Columbia. A study of high-{Tc} superconductors was done at TRIUMF during the third week of December 1996 by C.E. Stronach and D.R. Noakes

Nature of the Triple Point in Chromium Alloys: Mode-Softening of the Incommensurate Spin Density Wave

The magnetic stiffness parameter, A2, associated with the critical fluctuations in the paramagnetic phase close to the incommensurate spin-density-wave (SDW) transition of a Cr+0.18at.%Re single crystal, when compared with that of in pure chromium and dilute alloys of vanadium in chromium, indicates that the singularity responsible for the onset of the commensurate SDW phase occurs when A2 approaches zero at a finite value of the incommensurability parameter, delta 0.017 rlu, instead of zero as usually assumed. The mode of the incommensurate SDW softens as delta approaches this critical value with rhenium doping, and conversely hardens as delta increases when vanadium is added to chromium. Also, the amplitude of the critical scattering increases as delta approaches its end point, by a factor of about two going from 0.2 and 0.5at.%V to pure chromium, and by another factor near two in going from pure Cr to Cr+0.18at.%Re

Field dependence on texture in HTc's

International audienc

Valence and delocalization of yb in the Chevrel-phase YbMo 6 S 8

Mãssbauer isomer-shift measurements show that Yb is divalent in YbMo6Sg. The asymmetry of the Yb thermal vibration at 4.2 K obtained from the Goldanskii-Karyagin effect is much smaller than that obtained from a Rietveld refinement of neutron powder diffraction data at 16 K. This suggests that the displacement of Yb off the origin includes a significant, ~0.1-Å, static component which persists at low temperature. Full structural refinements at 16, 77, and 295 K show several interesting structural changes versus temperature