Theory of impurity-induced infrared absorption in cubic crystals

A method to calculate the infrared absorption due to a very low concentration of defects in a diatomic cubic crystal is developed directly from the basic absorption equation in quantum mechanics when the impurity produces changes in mass and short-range force constants. It is shown that the absorption is due to the modes of T1u symmetry about the defect and is proportional to the square of the projection of the amplitudes of the ions in the defect space onto the transverse-optic modes at the zone center as determined by the perturbation. A procedure to calculate the amplitudes of the ion in the defect space for a given mode is outlined. The present method gives more physical insight into the problem than most of the Green\u27s-function formalisms used in the field

Renal Cell Carcinoma Presenting as Metastasis to Scrotum and Spermatic Cord

Unusual site metastasis as presenting complaint of renal cell carcinoma (RCC) has been reported previously in literature. RCC is a notorious tumor with unpredictable behavior. We present a case of RCC who presented with scrotal mass and on subsequent investigation was found to have metastasis to scrotum and spermatic cord. Both testes were normal with no evidence of metastasis

Infrared Absorption Properties of LiH, LiD Mixed Crystals

The normal modes of pure LiH and LiD, required in impurity mode calculations, have been computed on the basis of the deformation-dipole model. Neutron-scattering results of Verble, Warren, and Yarnell for Li7D, along with some other experimental quantities, have been used to determine the various parameters involved. It is found that the frequency spectrum of LiH has a gap and that a substitutional D- ion produces a local mode in this gap whose frequency has been computed, together with its amplitude at the impurity. The infrared absorption frequency associated with this local mode and its integrated absorption have been computed as functions of D- content in the limit of low D- concentration. Also, we find an in-band resonance in the amplitude of the substitutional D- ion. Similar calculations have been carried out for H- impurities in LiD. The present results are compared with those of other calculations and with experiment

Interface-Controlled Ferroelectricity at the Nanoscale

Recent experimental results demonstrate that in thin films ferroelectricity persists down to film thickness of a few unit cells. This finding opens an avenue for novel electronic devices based on ultathin ferroelectrics, but also raises questions about factors controlling ferroelectricity and the nature of the ferroelectric state at the nanoscale. Here we report a first-principles study of KNbO3 ferroelectric thin films placed between two metal electrodes, either SrRuO3 or Pt. We show that the bonding at the ferroelectric-metal interface imposes severe constraints on the displacement of atoms, destroying the bulk tetragonal soft mode in thin ferroelectric films. This does not, however, quench local polarization. If the interface bonding is sufficiently strong the ground state represents a ferroelectric double-domain structure, driven by the intrinsic oppositely-oriented dipole moments at the two interfaces. Although the critical thickness for the net polarization of KNbO3 film is finite - about 1 nm for Pt and 1.8 nm for SrRuO3 electrodes - local polarization persists down to thickness of a unit cell.Comment: 5 pages, 4 figure

Stochastic Methods to Find Maximum Likelihood for Spam E-mail Classification

The increasing volume of unsolicited bulk e-mails leads to the need for reliable stochastic spam detection methods for the classification of the received sequence of e-mails. When a sequence of emails is received by a recipient during a time period, the spam filters have already classified them as spam or not spam. Due to the dynamic nature of the spam, there might be emails marked as not spam but are actually real spams and vice versa. For the sake of security, it is important to be able to detect real spam emails. This paper utilizes stochastic methods to refine the preliminary spam detection and to find maximum likelihood for spam e-mail classification. The method is based on the Bayesian theorem, hidden Markov model (HMM), and the Viterbi algorithm

Giant Electroresistance in Ferroelectric Tunnel Junctions

The interplay between the electron transport in metal/ferroelectric/metal junctions with ultrathin ferroelectric barriers and the polarization state of a barrier is investigated. Using a model which takes into account screening of polarization charges in metallic electrodes and direct quantum tunneling across a ferroelectric barrier we calculate the change in the tunneling conductance associated with the polarization switching. We find the conductance change of a few orders of magnitude for metallic electrodes with significantly different screening lengths. This giant electroresistance effect is the consequence of a different potential profile seen by transport electrons for the two opposite polarization orientations.Comment: 4 page

Nutritional assessment of mutants of Calocybe indica produced by protoplast mutagenesis

Mushrooms are rich source of protein, minerals and antioxidants. Nutritive value of mushrooms differs not only among genus but also among species. Nutritional content of mushrooms are being constantly reported. In present study, emphasis is laid on effect of mutational study on nutritional parameters of mushroom. A total of seven mutants of Calocybe indica obtained through physical and chemical mutagenic treatment were subjected to nutritional evaluation. Five mutants (CMU-5, CMN-9, CMN-11, CMN-2 and CMB-4) indicated higher protein content while ash content was also found more for all the mutants except CMN-9. Tocopherol content was also higher for all the mutants except CMN-3. ?-carotene was more from 2 mutants, CMU-2 and CMN-9. Lycopene content was better in CMU-2, CMN-9, CME-2 and CMB-4 while ascorbic acid content for CMU-2 and CMN-3 was better than that of the parent. Fat content was found to be significantly low only in mutant CMN-9 (1.24g/100g). CMN-9, mutant obtained through NTG treatment, was found better than the parent, Ci-3, not only in protein content but also in amount of vitamin A, C and E. It is indicated from the study that mutagenesis which leads to genotypic variation has effect on biochemical aspects as well. Therefore, various genetic manipulations can be exploited for nutritional enhancement aspects which need to be emphasized keeping in view the need of food quality in today’s scenario

The Health-Seeking Behavior of Leprosy Patients: An explanatory model

The way people interpret their diseases/illness and its treatment, or the meanings of these, has a direct impact on the way populations at the community and reagional levels deal with their illness as well as the treatments sought and chosen. Our study sets out to assess the socio-demographic profile of leprosy patients and their health-seeking behaviour. We also explore certain cultural factors hallmarking local, traditional remedial choices and as to how this presents an obstacle to effective treatement and consultation. This said, our study further considers how cultural variations lead to interpreting the signs and symptoms of leprosy, that is, to different ways of seeing symptoms and ailments

Prediction of a Switchable Two-Dimensional Electron Gas at Ferroelectric Oxide Interfaces

The demonstration of a quasi-two-dimensional electron gas (2DEG) in LaAlO3=SrTiO3 heterostructures has stimulated intense research activity in recent years. The 2DEG has unique properties that are promising for applications in all-oxide electronic devices. For such applications it is desirable to have the ability to control 2DEG properties by external stimulus. Here, based on first-principles calculations we predict that all-oxide heterostructures incorporating ferroelectric constituents, such as KNbO3=ATiO3 (A = Sr, Ba, Pb), allow creating a 2DEG switchable between two conduction states by ferroelectric polarization reversal. The effect occurs due to the screening charge at the interface that counteracts the depolarizing electric field and depends on polarization orientation. The proposed concept of ferroelectrically controlled interface conductivity offers the possibility to design novel electronic devices