Optical Visualization of Radiative Recombination at Partial Dislocations in GaAs

Individual dislocations in an ultra-pure GaAs epilayer are investigated with spatially and spectrally resolved photoluminescence imaging at 5~K. We find that some dislocations act as strong non-radiative recombination centers, while others are efficient radiative recombination centers. We characterize luminescence bands in GaAs due to dislocations, stacking faults, and pairs of stacking faults. These results indicate that low-temperature, spatially-resolved photoluminescence imaging can be a powerful tool for identifying luminescence bands of extended defects. This mapping could then be used to identify extended defects in other GaAs samples solely based on low-temperature photoluminescence spectra.Comment: 4 pages, 4 figure

Inequalities in Health and Service Use among People with Borderline Intellectual Impairment

This report, produced in collaboration with Professor Angela Hassiotis and others, sets out the extent to which people with borderline intellectual impairment face inequalities in health and use of services compared with the rest of the population, and seeks to improve awareness of these inequalities. Findings - Borderline intellectual impairment is common, affecting at least one adult in ten in England. The term is used here to refer to people with good verbal skills and living in private households, but who may experience cognitive impairments. - The findings in this report are consistent with previous research: people with borderline intellectual impairment are a disadvantaged group and their needs are not well understood. - Such adults face high levels of poor mental health, poorer general health, and many limitations in their daily lives. - Their level of use of mental health treatment and services does not appear to be commensurate with their higher level of need. This indicates that they are underserved compared with the rest of the population. - This may be due to a lack of professional awareness of their needs, to services not adapting enough to meet those needs, or to difficulties the individual faces in seeking treatment and support. - Adults with borderline intellectual impairment constitute key users of primary and secondary health care, and employment, education and welfare support. Improving awareness of the needs of this group should form part of wider plans to reduce inequalities in health and service use in England. Methods Secondary analysis of data from the Adult Psychiatric Morbidity Survey (APMS) was conducted to profile the circumstances of people with borderline intellectual impairment. APMS is one of the most authoritative and comprehensive national household surveys to assess both intellectual functioning and mental health in adults in England

Primary intraosseous mucoepidermoid carcinoma of maxilla- case report

Primary intraosseous mucoepidermoid carcinoma (PIOC) of the jaw bones is an extremely rare malignant salivary gland tumour constituting 2-4.3% of all the reported mucoepidermoid carcinomas (MEC). It is commonly seen in the posterior part of the mandible and rare in maxilla. The aetiopathogenesis of the PIOC is not completely understood. We hereby, report a case of PIOC of the maxilla in an 18 year old male patient. An incisional biopsy was performed, and the histopathological findings confirmed intermediate-grade mucoepidermoid carcinoma. Maxillary MEC have a worse prognosis than mandibular cases and it should be followed-up for a longer period due to the possibility of late recurrence or regional metastasis

Dissociative Autoionization in (1+2)-photon Above Threshold Excitation of H2 Molecules

We have theoretically studied the effect of dissociative autoionization on the photoelectron energy spectrum in (1+2)-photon above threshold ionization(ATI) of H2 molecules. We have considered excitation from the ground state X-singlet-Sigma-g+(v=0,j) to the doubly excited autoionizing states of singlet-Sigma-u+ and singlet-Pi-u+ symmetry, via the intermediate resonant B-singlet-Sigma-u+(v=5,j) states. We have shown that the photoelectron energy spectrum is oscillatory in nature and shows three distinct peaks above the photoelectron energy 0.7 eV. This feature has been observed in a recent experiment by Rottke et al, J. Phys. B, Vol. 30, p-4049 (1997).Comment: 11 pages and 4 figure

Political ecology of tiger conservation in India: Adverse effects of banning customary practices in a protected area

acceptedVersio

Silicon materials task of the low cost solar array project. Phase 3: Effect of impurities and processing on silicon solar cells

The 13th quarterly report of a study entitled an Investigation of the Effects of Impurities and Processing on Silicon Solar Cells is given. The objective of the program is to define the effects of impurities, various thermochemical processes and any impurity-process interactions on the performance of terrestrial silicon solar cells. The Phase 3 program effort falls in five areas: (1) cell processing studies; (2) completion of the data base and impurity-performance modeling for n-base cells; (3) extension of p-base studies to include contaminants likely to be introduced during silicon production, refining or crystal growth; (4) anisotropy effects; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells. The quarterly activities for this report focus on tasks (1), (3) and (4)

Some entanglement features of three-atoms Tavis-Cummings model: Cooperative case

In this paper we consider a system of identical three two-level atoms interacting at resonance with a single-mode of the quantized field in a lossless cavity. The initial cavity field is prepared in the coherent state while the atoms are taken initially to be either in the uppermost excited state "$|eee>$" or The $\textmd{GHZ}$-state or the $\textmd{W}$-state. For this system we investigate different kinds of atomic inversion and entanglement, which arise between the different parts of the system due to the interaction. Also the relationship, between entanglement and some other nonclassical effects in the statistical properties, such as collapses and revivals in the atomic inversion where superharmonic effects appear, is discussed. The $Q$-functions for different cases are discussed. Most remarkably it is found that the $\textmd{GHZ}$-state is more robust against energy losses, showing almost coherent trapping and Schr\"odinger-cat states can not be produced from such state. Also the entanglement of $\textmd{GHZ}$-state is more robust than the $\textmd{W}$-state. Another interesting feature found is that the state which has no pairwise entanglement initially will have a much improvement of such pairwise entanglement through the evolution. Sudden death and sudden revival of atoms-pairwise entanglement are produced with the $\textmd{W}$-state.Comment: 14 pages, 7 figure