The orientational dynamics of a spherical magnetic particle in linear shear flow subjected to an oscillating magnetic field in the flow plane is analysed in the viscous limit. The shear is in the $X$–$Y$ plane, the magnetic field is in the $X$ direction and the vorticity is perpendicular to the flow in the $Z$ direction. The relevant dimensionless groups are $\omega ^\ast$, the ratio of the frequency of the magnetic field and the strain rate, and $\varSigma$, the ratio of the magnetic and hydrodynamic torques. As $\varSigma$ is decreased, there is a transition from in-plane rotation, where the rotation is in the flow ($X$–$Y$) plane, to out-of-plane rotation, where the orientation vector is not necessarily in the $X$–$Y$ plane and the dynamics depends on the initial orientation. The particle rotation is phase-locked for in-plane rotation with discrete odd rotation number (number of rotations in one period of magnetic field oscillation), while the orbits are quasi-periodic with non-integer rotation number for out-of-plane rotation. For $\varSigma \gg 1$, regions of odd rotation number $n_o$ are bound by the lines $8 (n_o-1) \varSigma \omega ^\ast = 1$ and $8 (n_o+1) \varSigma \omega ^\ast = 1$, and there are discontinuous changes in the rotation number and mean and root-mean-square torque at these lines. For $\varSigma \ll 1$, the domains of in-plane rotation of finite width in the $\omega ^\ast$–$\varSigma$ plane extend into downward cusps at $\omega ^\ast = {1}/{2 n_o}$. The orbits are quasi-periodic between these domains, where the rotation is out of plane.

Rice landraces have been developed through artificial selection imposed by farmers during the long-term domestication process. Although the global rice diversity is well characterized, few studies have conducted an in-depth analysis of genetic diversity on a local scale. In India, there are many locally adapted non-Basmati aromatic rice landraces in which the pace of improvement is slow, despite their high economic values. The aromatic and quality rice landraces of Manipur, locally called Chakhao (delicious), are important, considering their high economic and cultural values. To conserve and encourage improvement of these landraces, we collected Chakhao accessions from eight districts of Manipur. The aim of the current study was to investigate the level of genetic diversity and structure of 37 Chakhao landraces based on genotyping with 47 microsatellite markers. The genetic diversity analysis revealed high gene diversity (0.673) within the Chakhao population, with values ranging from 0.303 (Poireiton) to 0.471 (mixed Chakhao). The Chakhao rice accessions could be divided into six subgroups based on genetic structure analyses. The population structure derived from the STRUCTURE analysis largely correlated with the farmers' classification of Chakhao landraces. The results of genetic diversity analyses and the indigenous knowledge of the names and use of Chakhao landraces would facilitate the conservation and utilization of this unique genetic resource.

A formalism for investigation of the propagation characteristics of various order short duration (pico second) Gaussian/dark hollow Gaussian laser pulse (DHGP) in a tunnel ionized plasma has been developed, which takes into account the electron-ion recombination. Utilizing the paraxial like approach, a nonlinear Schrödinger wave equation characterizing the beam spot size in space and time has been derived and solved numerically to investigate the transverse focusing (in space) and longitudinal compression (in time) of the laser pulse; the associated energy localization as the pulse advances in the plasma has also been analyzed. It is seen that in the absence of recombination the DHGP and Gaussian pulse undergo oscillatory and steady defocusing respectively. With the inclusion of recombination, the DHGP and Gaussian pulse both undergo periodic self-focusing for specific parameters. The DHGPs promise to be suitable for enhancement of energy transport inside the plasma.

The present report compares the macrophage function in rodent hosts susceptible and resistant to the human lymphatic filariid Brugia malayi. Macrophages from both mastomys (resistant) and gerbil (susceptible) infected intraperitoneally (i.p.) with the infective larvae (L3) of B. malayi were isolated from peritoneal lavage at different time-intervals and formation rate of NO, H2O2, O2−, TNF-α, glutathione peroxidase and reductase was assayed. NO release was found to be significantly increased in resistant mastomys as compared to gerbils and the release was markedly suppressed by i.p. administration of the NOS inhibitor aminoguanidine (AG). The AG-treated mastomys also demonstrated significantly greater establishment of larvae which correlated well with suppressed formation of NO. Nitric oxide synergizes with superoxide to form peroxynitrite radical (potent oxidant), which is known to be more toxic per se than NO. Results indicate the possible involvement of peroxynitrite in the rapid killing of larvae in the peritoneal cavity of mastomys. In contrast, the production of H2O2 was found to be enhanced in both species indicating that B. malayi L3 could withstand the toxic effects of H2O2. The higher level of glutathione peroxidase and reductase, as observed in mastomys compared with the gerbil after larval introduction, possibly protects the cell against the injurious effect of H2O2. The TNF-α level remained virtually unchanged in both the hosts, suggesting an insignificant role for this cytokine in parasite establishment.

Asian Indians are at high risk for the development of atherosclerosis and related complications, possibly initiated by higher body fat (BF). The present study attempted to establish appropriate cut-off levels of the BMI for defining overweight, considering percentage BF in healthy Asian Indians in northern India as the standard. A total of 123 healthy volunteers (eighty-six males aged 18–75 years and thirty-seven females aged 20–69 years) participated in the study. Clinical examination and anthropometric measurements were performed, and percentage BF was calculated. BMI for males was 21·4 (SD 3·7) KG/M2 AND FOR FEMALES WAS 23·3 (sd 5·5) kg/m2. Percentage BF was 21·3 (sd 7·6) in males and 35·4 (sd 5·0) in females. A comparison of BF data among Caucasians, Blacks, Polynesians and Asian ethnic groups (e.g. immigrant Chinese) revealed conspicuous differences. Receiver operating characteristic (ROC) curve analysis showed a low sensitivity and negative predictive value of the conventional cut-off value of the BMI (25 kg/m2) in identifying subjects with overweight as compared to the cut-off value based on percentage BF (males >25, females >30). This observation is particularly obvious in females, resulting in substantial misclassification. Based on the ROC curve, a lower cut-off value of the BMI (21·5 kg/m2 for males and 19·0 kg/m2 for females) displayed the optimal sensitivity and specificity, and less misclassification in identification of subjects with high percentage BF. Furthermore, a novel obesity variable, BF:BMI, was tested and should prove useful for interethnic comparison of body composition. In the northern Indian population, the conventional cut-off level of the BMI underestimates overweight and obesity when percentage BF is used as the standard to define overweight. These preliminary findings, if confirmed in a larger number of subjects and with the use of instruments having a higher accuracy of BF assessment, would be crucial for planning and the prevention and treatment of various obesity-related metabolic diseases in the Asian Indian population.

At very small layer spacings (< ∼2 nm) in Cu–Nb and Cu–Cr multilayers the Cu forms a metastable body-centered-cubic (bcc) structure and the films exhibit interesting mechanical properties. No information about the miscibility of bcc Cu in Nb or Cr is available and it is not known whether the films remain compositionally discrete. X-ray mapping in the analytical electron microscope has been used to study the compositional distributions in these films and show that they do remain discrete down to a layer spacing of 1.8 nm. A simple model for the experimentally measured distribution has been used to show that the expected analytical resolution has been achieved and that it should be possible to map layers with a spacing of 0.8 nm.

In this paper we report on the fabrication and characterization of GaN diodes (Schottky and p-n junctions) grown by plasma assisted MBE. We observed that Schottky diodes improve both in reverse as well as forward bias when deposited on 5 μm thick HVPE n+-GaN/sapphire instead of bare sapphire substrates. These improvements are attributed to the reduction of disloctions in the MBE homoepitaxially grown GaN. Similar benefits are observed in the reverse bias of the p-n junctions which according to EBIC measurements are attributed to the reduction of etch pits in the MBE grown p-GaN.

In this paper we report on the fabrication and characterization of GaN diodes (Schottky and p-n junctions) grown by plasma assisted MBE. We observed that Schottky diodes improve both in reverse as well as forward bias when deposited on 5 μm thick HVPE n+-GaN/sapphire instead of bare sapphire substrates. These improvements are attributed to the reduction of disloctions in the MBE homoepitaxially grown GaN. Similar benefits are observed in the reverse bias of the p-n junctions which according to EBIC measurements are attributed to the reduction of etch pits in the MBE grown p-GaN.

This paper presents results on the interfacial properties of Si3N4on NMOSFETs and PMOSFETs. Silicon nitride, formed by remote plasma enhanced chemical vapor deposition, was found to display severely degraded interfacial properties, in which the PMOS interfaces were significantly more degraded than NMOS interfaces. This is believed to be indicative of a relatively high density of interface traps located below the Si mid-gap that inhibit hole channel formation. These traps are believed to originate from the intrinsic nature of Si- Si3N4interface. Bonding constraint theory was applied to conclude that the Si-Si3N4interface is over-constrained compared to the Si-SiO2interface and consequently results in a higher intrinsic defectivity. A systematic study of the oxygen and hydrogen content in the silicon nitride film and its effect on electrical properties is also presented. Based on the electrical results it is concluded that the presence of oxygen either as a) a monolayer at the interface or b) within the silicon nitride film can produce high quality interfaces suitable for aggressively scaled CMOS devices.

In this study, trifluoroiodomethane (CF3I), a non-global-warming gas, has been investigated as a substitute for typical PFC's currently used in wafer patterning and CVD chamber cleaning processes. Dielectric films consisting of plasma enhanced chemically vapor deposited silicon dioxide and silicon nitride were comparatively etched in CF3I and C2F6/O2 plasma environments. The etch rate of these films was ascertained as a function of applied rf power, etchant gas flow rate, reaction chamber pressure, and CF3I: O2 ratio. Destruction efficiencies of CF3I at different processing parameters were evaluated. Depending on the flow rate, rf power, and chamber pressure, utilization efficiency of CF3I varied from as low as 10% to as high as 68%. CF4, C2F6, COF2, and CO2 were the predominant by-products found in the exhaust stream; however, their concentrations were very low compared to the traditional process employing C2F6/O2 mixtures.

To meet the stringent demands of high quality gate performance in advanced devices, a more robust gate dielectric is needed. A stacked structure consisting of thermal oxide and deposited oxide is a potential candidate since it offers certain advantages over single layer oxides such as 1) reduced defect density, 2) reduced stress at the SiO2/Si interface due to stress compensation between the thermal and the deposited oxide, 3) less silicon consumption and 4) reduced thermal budget. In this study, stacked oxides consisting of RTO and RTCVD oxides are characterized. In contrast to other studies which use conventional LPCVD methods to form the top oxide, these stacked oxides have the advantages of rapid thermal and in-situ processing, which produces excellent bulk and interfacial properties. Electrical characterization has shown that these stacked oxides have superior performance compared to single layer furnace or deposited oxides.

As the feature size of MOSFET devices shrink, issues such as thermal budget associated with controlling channel doping profiles and oxide growth kinetics raise concerns about using thermally grown furnace oxides for deep-submicron device applications. To address these concerns, we have developed a new RTCVD oxide process using a gas system of silane and nitrous oxide. The RTCVD oxides are deposited in a lamp-heated, cold wall, RTP system. Deposition rates ranging from 55 Å/min. to 624 Å/min. can be achieved at 800°C with silane nitrous oxide flow rate ratio of 2% and total pressure ranging from 3 to 10 Torr. The results indicate that this RTCVD process can be used to deposit both thin gate and thick isolation insulators for single wafer processing. Deposition rates of the RTCVD oxides exhibit a nonlinear dependence on the total deposition pressure. Electrical characterization of the as-deposited RTCVD oxides shows a mid-gap interface trap density of < 5×1010 eV−1 cm−2 and an average breakdown field of 13MV/cm. AES, RBS and TEM analyses have been used to study surface cleaning effects on the silicon-silicon dioxide interface quality and to determine the chemical composition of the RTCVD oxides. The results show that RTCVD oxides with stoichiometric composition and atomic flat silicon-silicon dioxide interface can be achieved using silane nitrous oxide flow rate ratio of <2%. I-V characteristics and transconductance degradation under hot carrier stress for MOSFET's using as-deposited RTCVD gate oxides have been found to be comparable to those of MOSFET's using thermal gate oxides.

A combination of i) low-temperature, 300-400°C, plasma-assisted oxidation to form the SiO2/Si interfaces, and ii) 800°C rapid thermal chemical vapor deposition, RTCVD, to deposit SiO2 thin films have been used to fabricate gate-oxide heterostructures. This sequence separates SiO2/Si interface formation by the oxidation process from the deposition of the bulk oxide layer by RTCVD. These two processes were performed in situ and sequentially in a single-chamber, ultraclean quartz reactor system. We have studied the chemistry of the interface formation process by Auger electron spectroscopy, AES, and the electrical properties of MOS devices with Al electrodes by C-V techniques.

This paper describes the preparation of silicon-based metal oxide semiconductor, MOS, devices, capacitors and field effect transistors, FETs, using deposited oxide dielectrics. A critical aspect of the device fabrication process is the way the Si-SiO2 interface is formed; e.g., either before, during, or after the oxide deposition. We have studied different methods of fabricating Si-SiO2 heterostructures, and have concluded that the implementation of independently controllable and sequential process steps for (i) interface formation, and (ii) oxide deposition consistently yields MOS devices with electrical properties that are superior to those of devices fabricated under other processing conditions which include specifically interface formation during the oxide deposition.

A combination of i) low-temperature, 300-400°C, plasma-assisted oxidation to form the SiO2/Si interfaces, and ii) 800°C rapid thermal chemical vapor deposition, RTCVD, to deposit SiO2 thin films have been used to fabricate gate-oxide heterostructures. This sequence separates SiO2/Si interface formation by the oxidation process from the deposition of the bulk oxide layer by RTCVD. These two processes were performed in situ and sequentially in a single-chamber, ultraclean quartz reactor system. We have studied the chemistry of the interface formation process by Auger electron spectroscopy, AES, and the electrical properties of MOS devices with Al electrodes by C-V techniques.

Chemical reaction can occur at the fiber/matrix interface of intermetallic matrix composites, leading to a degradation of mechanical properties. Fe–40Al matrix composites were fabricated using SiC, B, W, Mo-base, and Al2O3 fibers. Composite samples were heat treated up to 1500 K to study the reaction kinetics, and reaction rates were determined from reaction zone thickness measurements. The Al2O3 and W fibers were found to be compatible with the Fe–40Al matrix, while the Mo-based fibers reacted moderately and the B and SiC fibers reacted severely. Experimental results are compared to theoretical thermodynamic predictions.

The Didwana region has preserved lower palaeolithic artefacts in primary and semi-primary contexts. On the basis of geological stratigraphy of aeolian and playa sediments, artefacts occurring in a stratified context have been dated to the Middle Pleistocene. In order to work out technological evolutionary trends of the acheulian culture in this region, 301 handaxes from 10 localities have been studied following Roe's methodology, with some additional attributes. Some differences in size, shape and refinement are apparent between the collections. Statistics, diagrams, factor and cluster analyses suggest a technological evolution within the assemblages and therefore indicate the chronology of the sites. Compared with those of other known Indian sites, these handaxes may correspond to cultural stages ranging between early acheulian and very late acheulian or even early middle palaeolithic.