Mössbauer spectroscopic studies of Fe-substituted YIG

Compositional dependence of hyperfine parameters, determined through Mössbauer spectral analysis has been studied for Y_3−xFe_5+xO₁₂ (x = 0.0, 0.1, 0.3 and 0.5) garnet system at 300 K. The Mössbauer spectra have been fitted with three sextets in the ferrimagnetic state corresponding to Fe³⁺ ions at tetrahedral (d), octahedral (a) and dodecahedral (c) sites of the crystal structure. It is observed that isormershift, quadrupole shift and hyperfine field of d-site show no significant variation with Fe³⁺ concentration. The change in hyperfine fields of a- and c-sites with composition (x) has been explained on the basis of strength of exchange integrals, change in isomershift can be understood due to s-electron charge distribution and asymmetric displacement of oxygen ions surrounding the a- and c-sites seems to be responsible for observable quadrupole shift. The magneton number values obtained from magnetization and Mossbauer data are in agreement to those calculated using Neel's three sublattice model of ferrimagnetism.     

Molecular characterization of erythrocyte glucose-6-phosphate dehydrogenase deficiency in Al-Ain District, United Arab Emirates

Operational skills involved in controlling a motor vehicle were measured in two groups of very healthy elderly drivers and a young control group to test the hypothesis that there are age-related declines in operational performance that may influence driver safety. An actual behind-the-wheel, standardized road test was employed using a motor vehicle equipped with sensors to record speed, braking activity, and lane position, as well as direction and magnitude of front-wheel and eye-movement excursions. The data from these sensors were used as dependent measures of operational performance. Older drivers made fewer steering and eye-movement excursions and drifted across the center line more frequently than the young control group. Younger drivers drove significantly faster and executed more braking applications than did their older counterparts. The motor-vehicle operational performance of older healthy drivers was related to visual-spatial attentional declines and the useful field of vision associated with the normal aging process.     

The use of intravenous intermediate dose melphalan and dexamethasone as induction treatment in the management of de novo multiple myeloma

The variable absorption of melphalan from the gastrointestinal tract results in response rates between 40 and 60%. High dose melphalan increases response rates but at the cost of increased morbidity and mortality. We have investigated intravenous intermediate dose melphalan and dexamethasone in the treatment of patients presenting with de novo multiple myeloma with the object of reducing toxicity while preserving an improved response rate compared to oral melphalan and prednisolone. The results show that this treatment can be delivered safely on an outpatient basis in patients up to the age of 78 yr; 82% of patients achieved an objective response and 30% a complete haematological and clinical remission. Median overall survival for the whole group is 37 months.     

The g-factor of conduction electrons in Cd3P2 at low temperatures

The g-factor of conduction electrons in Cd₃P₂ at low temperatures is calculated as a function of carrier concentration, taking into account the InSb-like electronic energy-band structure of this material. In the case of typical samples with 10¹⁷, 5 × 10¹⁷, and 10¹⁸ electrons per cm³, we have determined the values of the magnetic field at which the extrema in the Shubnikov-de Haas and/or de Haas-van Alphen oscillations should occur, and suggested the experimental conditions under which effects due to spin splitting may be observed.On leave of absence from Centre de Recherches sur les Très Basses Températures, CNRS, and Service Basses Températures, Centre d'Etudes Nucléaires, Grenoble, France.     

The dependence ofg-factor on the electron concentration in cadmium arsenide at low temperatures

Theg-factor of conduction electrons in Cd₃As₂ at low temperatures is calculated as a function of carrier concentration, taking into account the inverted HgTe-type energy band structure of this material. In as-grown cadmium arsenide with 2×10 ¹⁸ electrons per cm ³ , the experimental conditions required to observe spin splitting are discussed.On leave of absence from Centre de Recherches sur les Très Basses Températures, CNRS, and Service des Basses Températures, Centre d'Etudes Nucléaires, Grenoble, France.     

Regional technological change in US coal mines: 1951–1976

This paper analyses technological change in coal mines in five regions—the Northern and Southern Appalachians, the Rocky Mountains, the Interior and Gulf and Northern Great Plains. Such an analysis can help identify the regions that are growth centres of the future and those that are the declining centres, so that an orderly transfer of manpower and resources from the latter to the former can be brought about efficiently and expeditiously. Section 2 deals with changes in production profiles, over time, of the regions by dividing coal mines into underground and surface mines. It concludes that the Appalachian regions are the declining regions with lower labour productivity and that the Northern Great Plains, with its increasing labour productivity, is the expanding region. Technological changes (TC) in underground mines consist of replacement of conventional mining machines by the continuous miners and the replacement of the latter by the long-wall machines. The TC in the surface mines is the substitution of intermediate- and large-sized power shovels and draglines (PS and Ds) for their smaller size counterparts. Section 3 presents a methodology of S-shaped growth curves. Section 4 reports empirical results for growth rates of adoption of the newer techniques across regions. These results reveal that the Northern Great Plains region is not absorbing the manpower and resources released by the Appalachian regions so that there are shortages in the former in the face of unemployment in the latter. There is, therefore, an opportunity for the declining Appalachian regions to inform their surplus manpower and resources about the growth centre in the north and prepare them for relocation, retraining and readjustment to the changes.     

Comparative genomic hybridization analysis of lobular carcinoma in situ and atypical lobular hyperplasia and potential roles for gains and losses of genetic material in breast neoplasia

Lobular carcinoma in situ (LCIS) and atypical lobular hyperplasia (ALH) of the breast are cytologically similar breast lesions that reportedly carry different relative risks of subsequent development of invasive carcinoma. They are frequently multifocal and bilateral. We have identified the chromosomal copy number changes in 31 LCIS and 14 ALH lesions from 28 cases and also the 7 invasive carcinomas that subsequently developed in 6 of these cases. This was achieved by comparative genomic hybridization analysis of microdissected formalin-fixed, paraffin-embedded material. There was no significant difference between the aberrations found in the unilateral versus the bilateral cases of LCIS. Loss of material from 16p, 16q, 17p, and 22q and also gain of material from 6q were found at a similar high frequency in LCIS and ALH. Loss of these genomic regions may indicate the locations of genes that predispose to the development of the lesions, and the results are consistent with LCIS and ALH representing the same genetic stage of development. Comparison of the comparative genomic hybridization results from LCIS/ALH with those from ductal carcinoma in situ and invasive cancer showed some similarities at the chromosomal level, but it also showed significant differences, including gain of 1q and 8q and evidence for genomic amplification, which were not found in LCIS/ALH. A genetic model is postulated for the possible relationships between noninvasive lobular lesions and invasive breast carcinoma, delineating potential roles for specific chromosome copy number changes.     

Measurement of the quasi-static C-V curves of an MIS structure in the presence of charge leakage

Two methods are demonstrated for obtaining the quasi-static C-V curves of an MIS structure containing a non-ideal insulator. Compensation for current leakage in the insulator is achieved by taking the difference in the total currents obtained for each polarity of the ramp voltage. In the second method, the compensated C-V curve is obtained by subtracting off the leakage current which is directly measured by scanning the bias voltage in a step-wise fashion. Tests to determine when these methods are successful are also discussed.