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A full band Monte Carlo study of the electron transport in 3C-SiC is presented based on an ab initio band structure calculation using the local density approximation to the density functional theory. The scattering rates and impact ionization transition rates have been calculated numerically from the ab initio band structure using both energy dispersion and numerical wave functions. This approach reduces the number of empirical parameters needed to a minimum. The two empirical coupling constants used have been deduced by fitting the simulated mobility as a function of lattice temperature to experimental data. The peak velocity was found to be approximately 2.2 × 10[sup 7] cm/s with a clear negative differential mobility above 600 kV/cm. The electron initiated impact ionization coefficients were found to be 2-10 times stronger than the reported values for the hole initiated impact ionization. [ABSTRACT FROM AUTHOR]

The ohmic transport of holes in p-type Al-doped 4H–SiC samples is investigated using a Monte Carlo tool based on a full-potential band structure. The temperature and doping dependence of the hole mobility and its anisotropy are calculated and discussed from a physical point of view, where we stress the importance of considering two-band conduction. Acoustic and optical phonon scattering, as well as ionized and neutral impurity scattering, have been considered. The Monte Carlo program also considers incomplete ionization of impurity atoms compatible with an Al ionization energy of 0.2 eV. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A response by D. V. Mann and his associates to a letter to the editor about their article on the affordable measurement of human energy expenditure using reduced dose doubly labeled water in the previous issue is presented.

A fully stochastic model for the imaging properties of X-ray silicon pixel detectors is presented. Both integrating and photon counting configurations have been considered, as well as scintillator-coated structures. The model is based on three levels of Monte Carlo simulations; photon transport and absorption using MCNP, full band Monte Carlo simulation of charge transport and system level Monte Carlo simulation of the imaging performance of the detector system. In the case of scintillator-coated detectors, the light scattering in the detector layers has been simulated using a Monte Carlo method. The image resolution was found to be much lower in scintillator-coated systems due to large light spread in thick scintillator layers. A comparison between integrating and photon counting readout methods shows that the image resolution can be slightly enhanced using a photon-counting readout. In addition, the proposed model has been used to study charge-sharing effects on the energy resolution in photon counting detectors. The simulation shows that charge-sharing effects are pronounced in pixel detectors with a pixel size below 170×170 μm2. A pixel size of 50×50 μm2 gives a highly distorted energy spectrum due to charge sharing. This negative effect can only be resolved by introducing advanced counting schemes, where neighbouring pixels communicate in order to resolve the charge sharing. [Copyright &y& Elsevier]

Background: Understanding how nursing students in European countries perceive their future professional role is an important step in creating awareness of the diversity and similarities between countries. Investigating nursing students' perceptions of their future profession could help in the design of education and the retention of nurses. Aim: To compare nursing students' perceptions of the professional nurse's role between Belarus, Lithuania, Poland and Sweden. Method: A cross‐sectional design was implemented. The study used two scales of the Professional Nursing Image Survey, which has questions about 10 skills and abilities and 14 functions and duties of a nurse. Results: A total of 392 final‐year nursing students in four countries participated in the study. Statistically significant differences were found between countries in terms of all 10 skills and abilities and in the distribution of responses concerning functions and duties of a nurse. Conclusions: Nursing students in Belarus, Lithuania, Poland and Sweden perceive differently the role of a nurse in terms of some functions and responsibilities. This may influence the adaptation of nurses who enjoy freedom of movement among the countries. Implications for nursing policy: The knowledge gained in this study could be beneficial in improving nursing education, as it could illuminate the discrepancy between educational goals and students' perceptions of their future professional role. [ABSTRACT FROM AUTHOR]