Bound-free pair production in ultra-relativistic ion collisions at the LHC collider: Analytic approach to the total and differential cross sections

A theoretical investigation of the bound-free electron-positron pair production in relativistic heavy ion collisions is presented. Special attention is paid to the positrons emitted under large angles with respect to the beam direction. The measurement of these positrons in coincidence with the down--charged ions is in principle feasible by LHC experiments. In order to provide reliable estimates for such measurements, we employ the equivalent photon approximation together with the Sauter approach and derive simple analytic expressions for the differential pair--production cross section, which compare favorably to the results of available numerical calculations. Based on the analytic expressions, detailed calculations are performed for collisions of bare Pb$^{82+}$ ions, taking typical experimental conditions of the LHC experiments into account. We find that the expected count rate strongly depends on the experimental parameters and may be significantly enhanced by increasing the positron-detector acceptance cone.Comment: 10 pages, 4 figure

‘The Coaching Needs of High Performance Female Athletes within the Coach-Athlete Dyad’

Within the research literature there is little work that has examined how coaches (and coaching) can positively influence female athletes’ continued participation and development in performance sport. With this in mind, utilising a grounded theory approach, this study focused on what are the coaching preferences of female athletes within the elite coachathlete dyad. Through interviews with 27 current high performance female athletes, four major coaching needs were found. These were: to be supported as person as well a performer, coaching to be a joint endeavour, the need for positive communication and finally, recognition of the salience of gender within the coach-athlete dyad. The findings provide evidence that the relational expertise of coaches is at the forefront of these women’s coaching needs. This study also demonstrates that for the participants, the coach-athlete relationship is at the heart of improving athletic training and performance, and that gender is an important influence on this relationship. Furthermore, the research highlights the strength of using an interpretive-qualitative paradigmatic approach to athlete preferences through foregrounding the women’s voices and experiences

Learning curves in orthopaedic surgery: a case for super-specialisation?

INTRODUCTION: The objective of this study was to assess if there is a significant learning curve in the treatment of developmental dysplasia of the hip. PATIENTS AND METHODS: We followed up cases of developmental dysplasia of the hip treated by a single surgeon over a 12-year period. There were 96 cases, 56 treated by open reduction and 40 treated by closed reduction. Assessment was made of the incidence and degree of avascular necrosis in the treated hips, as a radiological outcome measure. RESULTS: Plotting the cumulative percentage of satisfactory outcomes demonstrated an increasingly high percentage of satisfactory results with increasing number of procedures performed, i.e. as the surgeon progressed up the 'learning curve'. CONCLUSIONS: This study demonstrates a learning curve in the treatment of developmental dysplasia of the hip. It may be possible to draw parallels to other treatments, and also support for the growing trend to specialisatio

Famine in the People's Republic of China

2.00Available from British Library Document Supply Centre- DSC:6224.905(GU-DG-OPS--21) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo