Students' body image perceptions after completion of an anatomy course

Published ArticleA descriptive observational study was conducted among undergraduate medical students to determine whether the knowledge of Anatomy influenced their body image perceptions. The perception of some students regarding their body image and appearance was different after the course, and also their view of other peoples' bodies. The findings of the study support the literature that males are more concerned with muscularity and developing muscles, whereas females are more preoccupied with thinness. The study showed that a course in Anatomy might have an influence on students' perceptions of their own and other peoples' physical appearance

Guidelines for group work in an undergraduate learning programme

Published ArticleIt is required of higher education institutions in South Africa to provide for the development of general skills such as the ability to function in a team, and to apply group work as a method of instruction. After implementation of group work in the new five-year medical curriculum at the University of the Free State, it was realised that ineffective group dynamics and the inexperience of staff and students warranted clear and comprehensive guidelines for group work. For the development of these, opinions of students and staff involved, as well as inputs by experts on group work and literature findings, were evaluated. Their responses are reported and guidelines for effective group work are suggested

Guidelines for group work in an undergraduate learning programme

Published ArticleIt is required of higher education institutions in South Africa to provide for the development of general skills such as the ability to function in a team, and to apply group work as a method of instruction. After implementation of group work in the new five-year medical curriculum at the University of the Free State, it was realised that ineffective group dynamics and the inexperience of staff and students warranted clear and comprehensive guidelines for group work. For the development of these, opinions of students and staff involved, as well as inputs by experts on group work and literature findings, were evaluated. Their responses are reported and guidelines for effective group work are suggested

A new approach to evaluate gamma-ray measurements

Misunderstandings about the term random samples its implications may easily arise. Conditions under which the phases, obtained from arrival times, do not form a random sample and the dangers involved are discussed. Watson's U sup 2 test for uniformity is recommended for light curves with duty cycles larger than 10%. Under certain conditions, non-parametric density estimation may be used to determine estimates of the true light curve and its parameters

Soft X-ray seeding studies for the SLAC Linac Coherent Light Source II

We present the results from studies of soft X-ray seeding options for the LCLS-II X-ray free electron laser (FEL) at SLAC. The LCLS-II will use superconducting accelerator technology to produce X-ray pulses at up to 1 MHz repetition rate using 4 GeV electron beams. If properly seeded, these pulses will be nearly fully coherent, and highly stable in photon energy, bandwidth, and intensity, thus enabling unique experiments with intense high-resolution soft X-rays. Given the expected electron beam parameters from start to end simulations and predicted FEL performance, our studies reveal echo enabled harmonic generation (EEHG) and soft X-ray self-seeding (SXRSS) as promising and complementary seeding methods. We find that SXRSS has the advantage of simplicity and will deliver 5-35 times higher spectral brightness than EEHG in the 1-2 nm range, but lacks some of the potential for phase-stable multipulse and multicolor FEL operations enabled by external laser seeding with EEHG

Calculation of the Coherent Synchrotron Radiation Impedance from a Wiggler

Most studies of Coherent Synchrotron Radiation (CSR) have only considered the radiation from independent dipole magnets. However, in the damping rings of future linear colliders, a large fraction of the radiation power will be emitted in damping wigglers. In this paper, the longitudinal wakefield and impedance due to CSR in a wiggler are derived in the limit of a large wiggler parameter $K$. After an appropriate scaling, the results can be expressed in terms of universal functions, which are independent of $K$. Analytical asymptotic results are obtained for the wakefield in the limit of large and small distances, and for the impedance in the limit of small and high frequencies.Comment: 10 pages, 8 figure

A Spectacular VHE Gamma-Ray Outburst from PKS 2155-304 in 2006

Since 2002 the VHE (>100 GeV) gamma-ray flux of the high-frequency peaked BL Lac PKS 2155-304 has been monitored with the High Energy Stereoscopic System (HESS). An extreme gamma-ray outburst was detected in the early hours of July 28, 2006 (MJD 53944). The average flux above 200 GeV observed during this outburst is ~7 times the flux observed from the Crab Nebula above the same threshold. Peak fluxes are measured with one-minute time scale resolution at more than twice this average value. Variability is seen up to ~600 s in the Fourier power spectrum, and well-resolved bursts varying on time scales of ~200 seconds are observed. There are no strong indications for spectral variability within the data. Assuming the emission region has a size comparable to the Schwarzschild radius of a ~10^9 solar mass black hole, Doppler factors greater than 100 are required to accommodate the observed variability time scales.Comment: 4 pages, 3 figures; To appear in the Proceedings of the 30th ICRC (Merida, Mexico

Longitudinal phase space manipulation in energy recovering linac-driven free-electron lasers

Energy recovering an electron beam after it has participated in a free-electron laser (FEL) interaction can be quite challenging because of the substantial FEL-induced energy spread and the energy anti-damping that occurs during deceleration. In the Jefferson Lab infrared FEL driver-accelerator, such an energy recovery scheme was implemented by properly matching the longitudinal phase space throughout the recirculation transport by employing the so-called energy compression scheme. In the present paper,after presenting a single-particle dynamics approach of the method used to energy-recover the electron beam, we report on experimental validation of the method obtained by measurements of the so-called "compression efficiency" and "momentum compaction" lattice transfer maps at different locations in the recirculation transport line. We also compare these measurements with numerical tracking simulations.Comment: 31 pages, 13 figures, submitted to Phys. Rev. Special Topics A&

1,1,2,2-Tetra­kis(1,3-benzoxazol-2-yl)ethene

The title compound, C30H16N4O4, reveals crystallographic and mol­ecular symmetry and accordingly the asymmetric unit comprises one half-mol­ecule. The dihedral angle between the planes of the two geminal benzoxazole rings is 74.39 (5)°. The packing features weak C—H⋯N and π–π inter­actions [centroid–centroid distance = 3.652 (1) Å]