The Band Gap in Silicon Nanocrystallites

The gap in semiconductor nanocrystallites has been extensively studied both theoretically and experimentally over the last two decades. We have compared a recent ``state-of-the-art'' theoretical calculation with a recent ``state-of-the-art'' experimental observation of the gap in Si nanocrystallite. We find that the two are in substantial disagreement, with the disagreement being more pronounced at smaller sizes. Theoretical calculations appear to over-estimate the gap. Recognizing that the experimental observations are for a distribution of crystallite sizes, we proffer a phenomenological model to reconcile the theory with the experiment. We suggest that similar considerations must dictate comparisons between the theory and experiment vis-a-vis other properties such as radiative rate, decay constant, absorption coefficient, etc.Comment: 5 pages, latex, 2 figures. (Submitted Physical Review B

Effect of herbicides on the carbohydrate and nitrogen contents of nutgrass (Cyperus rotundus L.)

The effect of four herbicides on the starch and nitrogen contents of the tubers, dry matter production, carbohydrate, amide, amino, ammonium and nitrate nitrogen contents of the foliage of nutgrass (Cyperus rotundus L.) under pot culture conditions was studied. The starch content of the tubers of nutgrass depleted maximum by the Embutox-plus and Tok E-25 when applied as foliar spray and soil placement, respectively. The foliar application of Embutox-plus and Tok E-25 appeared to have maximum reduction in the carbohydrate and different nitrogen contents in the foliage of nutgrass as compared with other herbicides used. Severe reduction in the amide and amino nitrogen was observed as against ammonium or nitrate nitrogen content on the application of herbicides

Studies on the efficacy of some herbicides on the control of weeds in Japanese mint

The present investigation was aimed to evaluate the effectiveness of nine herbicides in the control of weeds associated with Japanese mint (Mentha arvensis) crop. The chemical method of weed control used in this investigation was found to be very effective in preventing weed growth in the mint crop. As a result of herbicidal treatment, the weeds underwent a marked reduction in their dry matter accumulation, coupled with a significant increase in the yield of mint herb and mint oil. Of the different herbicides embutox plus applied as post-emergence treatment and tok E-25 applied in the pre-emergence stage were found to be effective weed-killers, contributing a significant increase in mint foliage and oil yields. Telvar was similarly effective on application at the post-emergence stage. Other herbicides,viz., 2, 4-D and bladex-O also yielded useful responses

Evaluation of Certain Insecticides and Repellents Against Ticks

The susceptibility of two commonly occurring species of Ixodid ticks viz., the cattle tick, Hyalomma anatolicum anatolicum Koch and the brown dog tick, Rhipicephalus sanguineus Latr to certain newer insecticdes was investigated under controlled environmental conditions. The repellency of diethyl toluamide (Deet) to the two species of ticks was also investigated by a specially devised laboratory technique. It was found that based on LC/sub 50/ values, the two species were most susceptible to pyrethrins followed by carbaryl whereas malathion was found least toxic to the ticks

Submicron gate InP power MISFET's with improved output power density at 18 and 20 GHz

The microwave characteristics are presented at 18 and 20 GHz of submicron gate indium phosphide (InP) metal-insulator-semiconductor field-effect transistors (MISFET's) for high output power density applications. InP power MISFET's were fabricated and the output power density was investigated as a function of drain-source spacing. The best output power density and gain were obtained for drain-source spacing of 3 microns. The output power density is 2.7 times greater than was previously measured for InP MISFET's at 18 and 20 GHz, and the power-added efficiency also increased

Augmenting graphs to minimize the diameter

We study the problem of augmenting a weighted graph by inserting edges of bounded total cost while minimizing the diameter of the augmented graph. Our main result is an FPT 4-approximation algorithm for the problem.Comment: 15 pages, 3 figure

A preliminary study on the influence of gibberellic acid on Mentha arvensis Linn. var.piperascens holmes (Japanese mint)

"Gibberellic acid (GA3) solutions (10-200 p.p.m.) when sprayed onMentha arvensis Linn. var.piperascens at preflowering stage induces 30-50 per cent. increase in the yield of total herb. Apart from the elongation of internode, the leaf area was also increased. The stage of development of the plant at the time of treatment, appeared to be a significant factor in obtaining favourable Gibberellin effects. Pre-soaking of the suckers in GA solution induced early sprouting. Essential oil obtained from the treated leaves, however, decreased by 5-15 per cent. but had no deleterious effect on menthol contents."Mentha arvensis Linn. var.piperascens (Japanese mint) which has been introduced in India by the Regional Research Laboratory, Jammu, is now fairly well established for commercial exploitation of natural Menthol. During the course of investigation on the influence of Gibberellic Acid (GA) on various aromatic plants, the authors studied its effect on the growth, volatile oil and Menthol contents of this mint

Human Granuloma In Vitro Model, for TB Dormancy and Resuscitation

Tuberculosis (TB) is responsible for death of nearly two million people in the world annually. Upon infection, Mycobacterium tuberculosis (Mtb) causes formation of granuloma where the pathogen goes into dormant state and can live for decades before resuscitation to develop active disease when the immune system of the host is weakened and/or suppressed. In an attempt to better understand host-pathogen interactions, several groups have been developing in vitro models of human tuberculosis granuloma. However, to date, an in vitro granuloma model in which Mtb goes into dormancy and can subsequently resuscitate under conditions that mimic weakening of the immune system has not been reported. We describe the development of a biomimetic in vitro model of human tuberculosis granuloma using human primary leukocytes, in which the Mtb exhibited characteristics of dormant mycobacteria as demonstrated by (1) loss of acid-fastness, (2) accumulation of lipid bodies (3) development of rifampicin-tolerance and (4) gene expression changes. Further, when these micro granulomas were treated with immunosuppressant anti-tumor necrosis factor-alpha monoclonal antibodies (anti-TNF alpha mAbs), resuscitation of Mtb was observed as has been found in humans. In this human in vitro granuloma model triacylglycerol synthase 1deletion mutant (Delta tgs1) with impaired ability to accumulate triacylglycerides (TG), but not the complemented mutant, could not go into dormancy. Deletion mutant of lipY, with compromised ability to mobilize the stored TG, but not the complemented mutant, was unable to come out of dormancy upon treatment with anti-TNF alpha mAbs. In conclusion, we have developed an in vitro human tuberculosis granuloma model that largely exhibits functional features of dormancy and resuscitation observed in human tuberculosis

Annotated bibliography of research in the teaching of English

The committee reviews important research works in the teaching of English that have been published in the last year. Committee members include Richard Beach, Martha Bigelow, Martine Braaksma, Deborah Dillon, Jessie Dockter, Lee Galda, Lori Helman, Tanja Janssen, Karen Jorgensen, Richa Kapoor, Lauren Liang, Bic Ngo, David O’Brien, Mistilina Sato, and Cassie Scharber