Crossing the Boundary: a study of the nature and extent of racism in local league cricket

Since the start of the 1993/4 football season the 'Let's Kick Racism Out of Football’ has had some success in persuading clubs and players to recognise racism in the game and act to counter it. This summer, following our own research (Long et al, 1995) the Rugby Football League and the Commission for Racial Equality launched a 13-point Action Plan for professional clubs to adopt. Within cricket 'Hit Racism for Six' (HR46) was set-up last year to act as a pressure group to stimulate discussion about racism in cricket. Issues of race and racism in sport have recently attracted considerable media attention and stimulated popular debate. Emotion has run high over the articles by Robert Henderson (1995) and Roger Bannister (Connor 1995), the continuing confrontation between Raymond Illingworth and Devon Malcolm, the Botham/Lamb v Khan court case and the trouble on the terraces at Headingley during the summer of 1996. The balance attempted by programmes in the Radio 5 series on ‘Race around the UK’ represented one attempt to encourage a more considered approach, but throughout it has been clear that there is still a shortage of substantive research on race in sport. The Carnegie National Sports Development Centre conducted a study of black and ethnic minorities in cricket in Yorkshire that focused on issues of participation and sports development. Following the success of our rugby league project, Leeds City Council were keen for us to try to explore the more sensitive issues around race and racism. While the study of rugby league had been on the professional game this study of cricket was to be of local league cricket. Within the region this is how most people experience their cricket with some 1,300 teams affiliated to the Yorkshire Cricket Association. To establish views on race and racism we sought responses from: a) the secretaries of local league clubs b) Asian, black and white players in the leagues c) league umpire

The dynamical fate of planetary systems in young star clusters

We carry out N-body simulations to examine the effects of dynamical interactions on planetary systems in young open star clusters. We explore how the planetary populations in these star clusters evolve, and how this evolution depends on the initial amount of substructure, the virial ratio, the cluster mass and density, and the initial semi-major axis of the planetary systems. The fraction of planetary systems that remains intact as a cluster member, fbps, is generally well-described by the functional form fbps=f0(1+[a/a0]^c)^-1, where (1-f0) is the fraction of stars that escapes from the cluster, a0 the critical semi-major axis for survival, and c a measure for the width of the transition region. The effect of the initial amount of substructure over time can be quantified as fbps=A(t)+B(D), where A(t) decreases nearly linearly with time, and B(D) decreases when the clusters are initially more substructured. Provided that the orbital separation of planetary systems is smaller than the critical value a0, those in clusters with a higher initial stellar density (but identical mass) have a larger probability of escaping the cluster intact. These results help us to obtain a better understanding of the difference between the observed fractions of exoplanets-hosting stars in star clusters and in the Galactic field. It also allows us to make predictions about the free-floating planet population over time in different stellar environments.Comment: 14 pages, 9 figures, accepted for publication in MNRA

Effect of time delay on feedback control of a flashing ratchet

It was recently shown that the use of feedback control can improve the performance of a flashing ratchet. We investigate the effect of a time delay in the implementation of feedback control in a closed-loop collective flashing ratchet, using Langevin dynamics simulations. Surprisingly, for a large ensemble, a well-chosen delay time improves the ratchet performance by allowing the system to synchronize into a quasi-periodic stable mode of oscillation that reproduces the optimal average velocity for a periodically flashing ratchet. For a small ensemble, on the other hand, finite delay times significantly reduce the benefit of feedback control for the time-averaged velocity, because the relevance of information decays on a time scale set by the diffusion time of the particles. Based on these results, we establish that experimental use of feedback control is realistic.Comment: 6 pages, 6 figures, to appear in Europhysics Letter

Macromolecular separation through a porous surface

A new technique for the separation of macromolecules is proposed and investigated. A thin mesh with pores comparable to the radius of gyration of a free chain is used to filter chains according to their length. Without a field it has previously been shown that the permeability decays as a power law with chain length. However by applying particular configurations of pulsed fields, it is possible to have a permeability that decays as an exponential. This faster decay gives much higher resolution of separation. We also propose a modified screen containing an array of holes with barb-like protrusions running parallel to the surface. When static friction is present between the macromolecule and the protrusion, some of the chains get trapped for long durations of time. By using this and a periodic modulation of an applied electric field, high resolution can be attained.Comment: 18 pages latex, 6 postscript figures, using psfi

The Link Between Ejected Stars, Hardening and Eccentricity Growth of Super Massive Black Holes in Galactic Nuclei

The hierarchical galaxy formation picture suggests that super massive black holes (MBHs) observed in galactic nuclei today have grown from coalescence of massive black hole binaries (MBHB) after galaxy merging. Once the components of a MBHB become gravitationally bound, strong three-body encounters between the MBHB and stars dominate its evolution in a "dry" gas free environment, and change the MBHB's energy and angular momentum (semi-major axis, eccentricity and orientation). Here we present high accuracy direct N-body simulations of spherical and axisymmetric (rotating) galactic nuclei with order a million stars and two massive black holes that are initially unbound. We analyze the properties of the ejected stars due to slingshot effects from three-body encounters with the MBHB in detail. Previous studies have investigated the eccentricity and energy changes of MBHs using approximate models or Monte-Carlo three body scatterings. We find general agreement with the average results of previous semi-analytic models for spherical galactic nuclei, but our results show a large statistical variation. Our new results show many more phase space details of how the process works, and also show the influence of stellar system rotation on the process. We detect that the angle between the orbital plane of the MBHBs and that of the stellar system (when it rotates) influences the phase-space properties of the ejected stars. We also find that massive MBHB tend to switch stars with counter-rotating orbits into co-rotating orbits during their interactions.Comment: 22 pages, 8 figures, accepted for publication in Ap

Close encounters involving free-floating planets in star clusters

Instabilities in planetary systems can result in the ejection of planets from their host system, resulting in free-floating planets (FFPs). If this occurs in a star cluster, the FFP may remain bound to the star cluster for some time and interact with the other cluster members until it is ejected. Here, we use $N$-body simulations to characterise close star-planet and planet-planet encounters and the dynamical fate of the FFP population in star clusters containing $500-2000$ single or binary star members. We find that FFPs ejected from their planetary system at low velocities typically leave the star cluster 40% earlier than their host stars, and experience tens of close ($<1000$ AU) encounters with other stars and planets before they escape. The fraction of FFPs that experiences a close encounter depends on both the stellar density and the initial velocity distribution of the FFPs. Approximately half of the close encounters occur within the first 30 Myr, and only 10% occur after 100 Myr. The periastron velocity distribution for all encounters is well-described by a modified Maxwell-Bolzmann distribution, and the periastron distance distribution is linear over almost the entire range of distances considered, and flattens off for very close encounters due to strong gravitational focusing. Close encounters with FFPs can perturb existing planetary systems and their debris structures, and they can result in re-capture of FFPs. In addition, these FFP populations may be observed in young star clusters in imaging surveys; a comparison between observations and dynamical predictions may provide clues to the early phases of stellar and planetary dynamics in star clusters.Comment: Accepted for publication in MNRAS; 18 pages, 12 figure

A New Linear Inductive Voltage Adder Driver for the Saturn Accelerator

Saturn is a dual-purpose accelerator. It can be operated as a large-area flash x-ray source for simulation testing or as a Z-pinch driver especially for K-line x-ray production. In the first mode, the accelerator is fitted with three concentric-ring 2-MV electron diodes, while in the Z-pinch mode the current of all the modules is combined via a post-hole convolute arrangement and driven through a cylindrical array of very fine wires. We present here a point design for a new Saturn class driver based on a number of linear inductive voltage adders connected in parallel. A technology recently implemented at the Institute of High Current Electronics in Tomsk (Russia) is being utilized[1]. In the present design we eliminate Marx generators and pulse-forming networks. Each inductive voltage adder cavity is directly fed by a number of fast 100-kV small-size capacitors arranged in a circular array around each accelerating gap. The number of capacitors connected in parallel to each cavity defines the total maximum current. By selecting low inductance switches, voltage pulses as short as 30-50-ns FWHM can be directly achieved.Comment: 3 pages, 4 figures. This paper is submitted for the 20th Linear Accelerator Conference LINAC2000, Monterey, C

Maternal Performance of First-Calf Crossbred Beef Cowns in Relation to Sire Expected Progeny Differency (EPDs)

Cumulative milk production of crossbred daughters of sires of several breeds was estimated using weigh-suckle-weigh procedures. Pooled-across-breed analyses were conducted to determine, in retrospect, relationships of sire expected progeny difference (EPD) values for milk and total maternal value to daughter milk yield and daughter\u27s offspring weaning weight. The pooled coefficient for regression of daughter 214-day milk yield sire milk EPD was 13.4 Ib/lb (residual correlation was .14). The overall mean estimated milk yield was 2,782 Ib, suggesting that a difference in sire milk EPD of 1 Ib corresponded to a difference of approximately 5% in cumulative daughter milk yield. The pooled coefficient for regression of daughter\u27s offspring 214-day weight on sire total maternal EPD was 1.1 8 Ib/lb (residual correlation was .17). Breeders who use sire milk and total maternal EPD values as selection tools should expect such selection to be effective, on average, but should also expect that a substantial proportion of individuals or small groups may not rank as predicted

Relationship of Beef Sire Birth Weight and Weaning Weight Expected Progeny Differences to Actual Performance of Crossbred Offspring

Performance records from 1982 to 1992 on 1365 calves for birth weight (BW) and 1492 calves for weaning weight (WW) were analyzed to estimate relationships of purebred sire expected progeny difference (EPD) values for BW and WW to actual crossbred progeny performance. Sires of the calves were Polled Hereford, Simmental, Angus, Salers, Tarentaise, or Charolais. The pooled-across-breed regressions (Ib/lb + SE) of BW and WW of calves on sire EPD were 1 .I 7 ±.31 and .75 + .28, respectively. Residual correlations of BW with BW EPD and WW with WW EPD were .I6 (P\u3c -01) and .05 (P= .10), respectively. Additional regression and residual correlation analyses were conducted in which records from progeny of low-accuracy sires (Acc. \u3c .50) were deleted. The reduced data set included 967 records for BW and 962 records for WW. The pooled-across-breed regressions (Ib/lb + SE) of BW and WW of calves on higher-accuracy sire EPD were 1.28 + .35 and .71 ± .31, respectively. Residual correlations using higher-accuracy sire data of BW with BW EPD and WW with WW EPD were .I8 (P\u3c.01) and .09 (P = .02). Breeders who use BW and WW EPDs as a selection tool should expect such selection to be effective, on average, and reasonably consistent with theoretical expectation. However, some sires and small progeny groups may not rank as expected based on sire EPDs