Student perception of workplace-based assessment.

Workplace-based assessment (WPBA) is key to medical education, providing a framework through which the trainee can be assessed and receive feedback in the clinical setting. WPBA was introduced in 2008-2009 to students in year 4 at University College London Medical School (UCLMS). Students raised concerns about the lack of standardisation in grading. As a result, white-space areas were introduced on WPBA forms. The aim of this was to permit assessors to expand their feedback, thereby enhancing its developmental potential. The aim of the project was to assess student perception of WPBA at UCLMS, and to determine whether re-designing the form had altered this perception

Ovarian hormones and pituitary responsiveness to gonadotrophin releasing hormone in mice

In the present study the role of progesterone and oestradiol in modulating the responsiveness at the anterior pituitary gland to gonadotrophin releasing hormone (GN-RH) was investigated by measuring the release of luteinizing hormone (LH) in ovariectomised mice which had been pretreated with these steroids.A significant release of LH was seen in the animals receiving GN-RH. Pretreatment with oestrogen and progesterone depressed LH levels in the animals which did not receive GN-RH, and resulted in a larger release of LH in the animals receiving GN-RH in comparison with the control group pretreated with oil

Scaling Behaviour and Complexity of the Portevin-Le Chatelier Effect

The plastic deformation of dilute alloys is often accompanied by plastic instabilities due to dynamic strain aging and dislocation interaction. The repeated breakaway of dislocations from and their recapture by solute atoms leads to stress serrations and localized strain in the strain controlled tensile tests, known as the Portevin-Le Chatelier (PLC) effect. In this present work, we analyse the stress time series data of the observed PLC effect in the constant strain rate tensile tests on Al-2.5%Mg alloy for a wide range of strain rates at room temperature. The scaling behaviour of the PLC effect was studied using two complementary scaling analysis methods: the finite variance scaling method and the diffusion entropy analysis. From these analyses we could establish that in the entire span of strain rates, PLC effect showed Levy walk property. Moreover, the multiscale entropy analysis is carried out on the stress time series data observed during the PLC effect to quantify the complexity of the distinct spatiotemporal dynamical regimes. It is shown that for the static type C band, the entropy is very low for all the scales compared to the hopping type B and the propagating type A bands. The results are interpreted considering the time and length scales relevant to the effect.Comment: 35 pages, 6 figure

Coupled Particle Transport and Pattern Formation in a Nonlinear Leaky-Box Model

Effects of particle-particle coupling on particle characteristics in nonlinear leaky-box type descriptions of the acceleration and transport of energetic particles in space plasmas are examined in the framework of a simple two-particle model based on the Fokker-Planck equation in momentum space. In this model, the two particles are assumed coupled via a common nonlinear source term. In analogy with a prototypical mathematical system of diffusion-driven instability, this work demonstrates that steady-state patterns with strong dependence on the magnetic turbulence but a rather weak one on the coupled particles attributes can emerge in solutions of a nonlinearly coupled leaky-box model. The insight gained from this simple model may be of wider use and significance to nonlinearly coupled leaky-box type descriptions in general

Rotons and Quantum Evaporation from Superfluid 4He

The probability of evaporation induced by $R^+$ and $R^-$ rotons at the surface of superfluid helium is calculated using time dependent density functional theory. We consider excitation energies and incident angles such that phonons do not take part in the scattering process. We predict sizable evaporation rates, which originate entirely from quantum effects. Results for the atomic reflectivity and for the probability of the roton change-mode reflection are also presented.Comment: 11 pages, REVTEX, 3 figures available upon request or at http://anubis.science.unitn.it/~dalfovo/papers/papers.htm

Compact Autonomous Explosive-Driven Pulsed Power System Based on a Capacitive Energy Storage Charged by a High-Voltage Shock-Wave Ferromagnetic Generator

A new concept for constructing compact autonomous pulsed power systems is presented. This concept utilizes a high-voltage explosive-driven shock-wave ferromagnetic generator (FMG) as a charging source for capacitive energy storage. It has been experimentally demonstrated that miniature FMGs (22-25 cm³ in size and 84-95 g in mass) developed for these experiments can be successfully used to charge capacitor banks. The FMGs, containing Nd₂Fe₁₄B energy-carrying elements, provided pulsed powers of 35-45 kW in times ranging from 10 to 15 µs. A methodology was developed for digital simulation of the operation of the transverse FMG. Experimental results that were obtained are in a good agreement with the results of digital simulations

High Voltage Charging of a Capacitor Bank

We have demonstrated the feasibility of charging a capacitor bank to a high voltage using an autonomous ultra-compact explosively driven source of prime power. The prime power source is a longitudinally driven shock wave depolarization of a ferroelectric ceramic. The energy-carrying elements of the shock wave ferroelectric generators (FEGs) were poled Pb(Zr52Ti48)O3 polycrystalline ceramic disks with 0.35 cm3 volume. FEGs charged 9 nF, 18 nF, and 36 nF capacitor banks and provided pulsed-power with peak amplitudes up to 0.29 MW. The maximum efficiency of electric charge transfer from shocked Pb(Zr52Ti48)O3 elements to a capacitor bank was 46%. We demonstrated experimentally that the FEG-capacitor bank system can perform as an oscillatory circuit. A methodology was developed for numerical simulation of the operation of the FEG-capacitor bank system; the simulation results were in a good agreement with the experimental results