Extended Scaling for the high dimension and square lattice Ising Ferromagnets

In the high dimension (mean field) limit the susceptibility and the second moment correlation length of the Ising ferromagnet depend on temperature as chi(T)=tau^{-1} and xi(T)=T^{-1/2}tau^{-1/2} exactly over the entire temperature range above the critical temperature T_c, with the scaling variable tau=(T-T_c)/T. For finite dimension ferromagnets temperature dependent effective exponents can be defined over all T using the same expressions. For the canonical two dimensional square lattice Ising ferromagnet it is shown that compact "extended scaling" expressions analogous to the high dimensional limit forms give accurate approximations to the true temperature dependencies, again over the entire temperature range from T_c to infinity. Within this approach there is no cross-over temperature in finite dimensions above which mean-field-like behavior sets in.Comment: 6 pages, 6 figure

Temperature dependence of an AlInP 63Ni betavoltaic cell

In this paper, the performance of an Al0.52In0.48P 63 Ni radioisotope cell is reported over the temperature range of −20 °C to 140 °C. A 400 μm diameter p+-i-n+ (2 μm i-layer) Al0.52In0.48P mesa photodiode was used as a conversion device in a novel betavoltaic cell. Dark current measurements on the Al0.52In0.48P detector showed that the saturation current increased increasing the temperature, while the ideality factor decreased. The effects of the temperature on the key cell parameters were studied in detail showing that the open circuit voltage, the maximum output power, and the internal conversion efficiency decreased when the temperature was increased. At −20 °C, an open circuit voltage and a maximum output power of 0.52 V and 0.28 pW, respectively, were measured

Pregnancy follow-up in a patient with mechanical valve: possible in sub-Saharan Africa?

Background: In Africa in general and in Cameroon in particular, post rheumatic cardiopathies are a health care problem, one of the causes of infertility in the women population and a major cause of death among children and adults. Management of a pregnant woman with mechanical heart valve is a complex issue for all health care providers involved in the care of such patients. Patient and case report: Miss A is 26-years old and consulted for cardiac assessment; referred from Bamenda (North-West province of Cameroon) for better management of a cardiac problem including arrhythmia and a history of recurrent tonsillitis. The cardiac echo-dopplerography showed severe post-rheumatic mitral valve regurgitation with pulmonary hypertension and a dysfunctional left ventricle. The patient was later evacuated in a surgical centre in Milan San Donato (Italy) where a St. Jude mechanical heart valve N.27 was implanted. Two years after surgery, during a follow-up visit, the patient brought a pelvic ultrasound showing a single live intrauterine foetus, gestational age estimated at 7 weeks. Conclusion: anagement of mechanical valve in a pregnancy context, resulting in a favourable outcome (no thromboembolic events and the delivery of a healthy baby) is possible in sub- Saharan Africa. Close observation, adherence to existing clinical guidelines, patient cooperation and an appropriate technical infrastructure are critical factors to consider

Temperature effects on gallium arsenide 63Ni betavoltaic cell

A GaAs 63Ni radioisotope betavoltaic cell is reported over the temperature range 70 °C to −20 °C. The temperature effects on the key cell parameters were investigated. The saturation current decreased with decreased temperature; whilst the open circuit voltage, the short circuit current, the maximum power and the internal conversion efficiency values decreased with increased temperature. A maximum output power and an internal conversion efficiency of 1.8 pW (corresponding to 0.3 μW/Ci) and 7% were observed at −20 °C, respectively

Gallium arsenide 55Fe X-ray-photovoltaic battery

The effects of temperature on the key parameters of a prototype GaAs 55Fe radioisotope X-ray microbattery were studied over the temperature range -20 °C to 70 °C. A p-i-n GaAs structure was used to collect the photons from a 254 Bq 55Fe radioisotope X-ray source. Experimental results showed that the open circuit voltage and the short circuit current decreased with increased temperature. The maximum output power and the conversion efficiency of the device decreased at higher temperatures. For the reported microbattery, the highest maximum output power (1 pW, corresponding to 0.4 μW/Ci) was observed at -20 °C. A conversion efficiency of 9% was measured at -20 °C

A study of logarithmic corrections and universal amplitude ratios in the two-dimensional 4-state Potts model

Monte Carlo (MC) and series expansion (SE) data for the energy, specific heat, magnetization and susceptibility of the two-dimensional 4-state Potts model in the vicinity of the critical point are analysed. The role of logarithmic corrections is discussed and an approach is proposed in order to account numerically for these corrections in the determination of critical amplitudes. Accurate estimates of universal amplitude ratios $A_+/A_-$, $\Gamma_+/\Gamma_-$, $\Gamma_T/\Gamma_-$ and $R_C^\pm$ are given, which arouse new questions with respect to previous works

Who Wants to Work in a Rural Health Post? The Role of Intrinsic Motivation, Rural Background and Faith-Based Institutions in Rwanda and Ethiopia

Most developing countries face shortages of health workers in rural areas. This has profound consequences for health service delivery, and ultimately for health outcomes. To design policies that rectify these geographic imbalances it is vital to understand what factors determine health workers' choice to work in rural areas. But empirical analysis of health worker preferences has remained limited due to the lack of data. Using unique contingent valuation data from a cohort survey of 412 nursing and medical students in Rwanda, this paper examines the determinants of future health workers' willingness to work in rural areas, as measured by rural reservation wages, using regression analysis. These data are also combined with those from an identical survey in Ethiopia to enable a two-country analysis. We find that health workers with higher intrinsic motivation – measured as the importance attached to helping the poor – as well as those who have grown up in a rural area, and Adventists who participate in a local bonding scheme are all significantly more willing to work in a rural area. The main Rwanda result for intrinsic motivation is strikingly similar to that obtained for Ethiopia and Rwanda together. These results suggest that in addition to economic incentives, intrinsic motivation and rural origin play an important role in health workers' decisions to work in a rural area, and that faith-based institutions matter.health care delivery, health workers, labour supply, public service

New extended high temperature series for the N-vector spin models on three-dimensional bipartite lattices

High temperature expansions for the susceptibility and the second correlation moment of the classical N-vector model (O(N) symmetric Heisenberg model) on the sc and the bcc lattices are extended to order $\beta^{19}$ for arbitrary N. For N= 2,3,4.. we present revised estimates of the critical parameters from the newly computed coefficients.Comment: 11 pages, latex, no figures, to appear in Phys. Rev.

Who Wants to Work in a Rural Health Post? The Role of Intrinsic Motivation, Rural Background and Faith-Based Institutions in Rwanda and Ethiopia

Background: Most developing countries face shortages of health workers in rural areas. This has profound consequences for health service delivery, and ultimately for health outcomes. To design policies that rectify these geographic imbalances it is vital to understand what factors determine health workers’ choice to work in rural areas. But empirical analysis of health worker preferences has remained limited due to the lack of data. Methods: Using unique contingent valuation data from a cohort survey of 412 nursing and medical students in Rwanda, this paper examines the determinants of future health workers’ willingness to work in rural areas, as measured by rural reservation wages, using regression analysis. These data are also combined with those from an identical survey in Ethiopia to enable a two-country analysis. Results: Health workers with higher intrinsic motivation - measured as the importance attached to helping the poor - as well as those who have grown up in a rural area, and Adventists who participate in a local bonding scheme are all significantly more willing to work in a rural area. The main Rwanda result for intrinsic motivation is strikingly similar to that obtained for Ethiopia and Rwanda together. Discussion: The results suggest that in addition to economic incentives, intrinsic motivation and rural origin play an important role in health workers’ decisions to work in a rural area, and that faith-based institutions matter.