Phonon dispersion curves and atomic mean square displacement for several fcc and bcc materials

The atomic mean square displacement (MSD) and the phonon dispersion curves (PDC's) of a number of face-centred cubic (fcc) and body-centred cubic (bcc) materials have been calclllated from the quasiharmonic (QH) theory, the lowest order (A2 ) perturbation theory (PT) and a recently proposed Green's function (GF) method by Shukla and Hiibschle. The latter method includes certain anharmonic effects to all orders of anharmonicity. In order to determine the effect of the range of the interatomic interaction upon the anharmonic contributions to the MSD we have carried out our calculations for a Lennard-Jones (L-J) solid in the nearest-neighbour (NN) and next-nearest neighbour (NNN) approximations. These results can be presented in dimensionless units but if the NN and NNN results are to be compared with each other they must be converted to that of a real solid. When this is done for Xe, the QH MSD for the NN and NNN approximations are found to differ from each other by about 2%. For the A2 and GF results this difference amounts to 8% and 7% respectively. For the NN case we have also compared our PT results, which have been calculated exactly, with PT results calculated using a frequency-shift approximation. We conclude that this frequency-shift approximation is a poor approximation. We have calculated the MSD of five alkali metals, five bcc transition metals and seven fcc transition metals. The model potentials we have used include the Morse, modified Morse, and Rydberg potentials. In general the results obtained from the Green's function method are in the best agreement with experiment. However, this improvement is mostly qualitative and the values of MSD calculated from the Green's function method are not in much better agreement with the experimental data than those calculated from the QH theory. We have calculated the phonon dispersion curves (PDC's) of Na and Cu, using the 4 parameter modified Morse potential. In the case of Na, our results for the PDC's are in poor agreement with experiment. In the case of eu, the agreement between the tlleory and experiment is much better and in addition the results for the PDC's calclliated from the GF method are in better agreement with experiment that those obtained from the QH theory.

A research capacity strengthening project for infectious diseases in Honduras: experience and lessons learned

Background: In Honduras, research capacity strengthening (RCS) has not received sufficient attention, but an increase in research competencies would enable local scientists to advance knowledge and contribute to national priorities, including the Millennium Development Goals (MDGs). Objective: This project aimed at strengthening research capacity in infectious diseases in Honduras, focusing on the School of Microbiology of the National Autonomous University of Honduras (UNAH). The primary objective was the creation of a research-based graduate program for the continued training of researchers. Parallel objectives included institutional strengthening and the facilitation of partnerships and networks. Methods: Based on a multi-stakeholder consultation, an RCS workplan was designed and undertaken from 2007 to 2012. Due to unexpected adverse circumstances, the first 2 years were heavily dedicated to implementing the project's flagship, an MSc program in infectious and zoonotic diseases (MEIZ). In addition, infrastructure improvements and demand-driven continuing education opportunities were facilitated; biosafety and research ethics knowledge and practices were enhanced, and networks fostering collaborative work were created or expanded. Results: The project coincided with the peak of UNAH's radical administrative reform and an unprecedented constitutional crisis. Challenges notwithstanding, in September 2009, MEIZ admitted the first cohort of students, all of whom undertook MDG-related projects graduating successfully by 2012. Importantly, MEIZ has been helpful in expanding the School of Microbiology's traditional etiology-based, disciplinary model to infectious disease teaching and research. By fulfilling its objectives, the project contributed to a stronger research culture upholding safety and ethical values at the university. Conclusions: The resources and strategic vision afforded by the project enhanced UNAH's overall research capacity and its potential contribution to the MDGs. Furthermore, increased research activity and the ensuing improvement in performance indicators at the prime Honduran research institution invoke the need for a national research system in Honduras.