Verbal autopsy of 48 000 adult deaths attributable to medical causes in Chennai (formerly Madras), India

BACKGROUND: In the city of Chennai, India, registration of the fact of death is almost complete but the cause of death is often inadequately recorded on the death certificate. A special verbal autopsy (VA) study of 48 000 adult deaths in Chennai during 1995–97 was conducted to arrive at the probable underlying cause of death and to measure cause specific mortality rates for Chennai. METHODS: Trained non-medical graduates with at least 15 years of formal education interviewed the surviving family members or an associate of the deceased to write a report on the complaints, symptoms, signs, duration and treatment details of illness prior to death. Each report was reviewed centrally by two physicians independently. The reliability was assessed by comparing deaths attributed to cancer by VA with records in Vital Statistics Department and Chennai Cancer Registry. RESULTS: The VA reduced the proportion of deaths attributed to unspecified medical causes and unknown causes from 37% to 7% in early adult life and middle age (25–69 yrs) and has yielded fewer unspecified causes (only 10%) than the death certificate. The sensitivity of VA to identify cancer was 94% in the age group 25–69. CONCLUSION: VA is practicable for deaths in early adult life or middle age and is of more limited value in old age. A systematic program of VA of a representative sample of deaths could assign broad causes not only to deaths in childhood (as has previously been established) but also to deaths in early adult life and middle age

Phonons and related properties of extended systems from density-functional perturbation theory

This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudo-potential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long wave-length vibrations in polar materials, the response to strain deformations, and higher-order responses. The success of this methodology is demonstrated with a number of applications existing in the literature.Comment: 52 pages, 14 figures, submitted to Review of Modern Physic

Advanced capabilities for materials modelling with Quantum ESPRESSO

Quantum ESPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudo-potential and projector-augmented-wave approaches. Quantum ESPRESSO owes its popularity to the wide variety of properties and processes it allows to simulate, to its performance on an increasingly broad array of hardware architectures, and to a community of researchers that rely on its capabilities as a core open-source development platform to implement theirs ideas. In this paper we describe recent extensions and improvements, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software

Intervalley scattering in GaAs: ab initio calculation of the effective parameters for Monte Carlo simulations

International audienc

Ab initio study of electron-phonon coupling and excitonic linewidth in GaAs under pressure and in GaP

International audienceInteractions between excited electrons and short-wavelength (intervalley) phonons are the major source for the broadening of the excitonic line in GaAs under pressure and in GaP. We have studied the intervalley scattering deformation potential using density functional theory for the conduction bands, and density functional perturbation theory for phonon frequencies and for the matrix elements of the electronphonon interaction. We have calculated the electronphonon scattering time due to intervalley scattering t, integrating the scattering probabilities over all possible final states in the Brillouin zone without any ad hoc assumption about the behavior of the electronphonon matrix elements nor the topology of the conduction band. We compare our theoretical results with time-resolved photoluminescence experiment in GaAs, and with spectroellipsometry measurements in GaAs under pressure and in GaP. We show that our ab initio method also allows the evaluation of effective deformation potential

Ab initio calculation of electron-phonon scattering time in germanium

International audienc

Theoretical intrinsic lifetime limit of shallow donor states in silicon

International audienceThe intrinsic lifetime of the 2p(0) shallow impurity state in silicon doped with P, As, Sb, or Bi has been computed by combining matrix elements of the electron-phonon coupling within the density-functional perturbation theory, with the envelope function approximation for the impurity wave functions. The theoretical lifetime due to the electronic interaction with intervalley phonons has been found to be 1.1 ns for P-doped silicon, and this theoretical limit is much longer than has been previously believed for the last five decades