Anomalous Defects and Their Quantized Transverse Conductivities

Using a description of defects in solids in terms of three-dimensional gravity, we study the propagation of electrons in the background of disclinations and screw dislocations. We study the situations where there are bound states that are effectively localized on the defect and hence can be described in terms of an effective 1+1 dimensional field theory for the low energy excitations. In the case of screw dislocations, we find that these excitations are chiral and can be described by an effective field theory of chiral fermions. Fermions of both chirality occur even for a given direction of the magnetic field. The ``net'' chirality of the system however is not always the same for a given direction of the magnetic field, but changes from one sign of the chirality through zero to the other sign as the Fermi momentum or the magnitude of the magnetic flux is varied. On coupling to an external electromagnetic field, the latter becomes anomalous, and predicts novel conduction properties for these materials.Comment: New material added. ReVTeX , 31 pgs., 4 figs.(uses epsf

Far Field Deposition Of Scoured Regolith Resulting From Lunar Landings

As a lunar lander approaches a dusty surface, the plume from the descent engine impinges on the ground, entraining loose regolith into a high velocity dust spray. Without the inhibition of a background atmosphere, the entrained regolith can travel many kilometers from the landing site. In this work, we simulate the flow field from the throat of the descent engine nozzle to where the dust grains impact the surface many kilometers away. The near field is either continuum or marginally rarefied and is simulated via a loosely coupled hybrid DSMC - Navier Stokes (DPLR) solver. Regions of two-phase and polydisperse granular flows are solved via DSMC. The far field deposition is obtained by using a staged calculation, where the first stages are in the near field where the flow is quasi-steady and the outer stages are unsteady. A realistic landing trajectory is approximated by a set of discrete hovering altitudes which range from 20m to 3m. The dust and gas motions are fully coupled using an interaction model that conserves mass, momentum, and energy statistically and inelastic collisions between dust particles are also accounted for. Simulations of a 4 engine configuration are also examined, and the erosion rates as well as near field particle fluxes are discussed.Astronom

First Order Derivative Spectrophotometric Determination of Thorium in Geological Samples Using Diacetylmonoxine ρ-hydroxybenzoylhydrazone

A simple, selective and sensitive spectrophotometric method has been developed for the determination of trace amounts of thorium using a newly synthesised reagent diacetylmonoximep-hydroxybenzoylhydrazone (DMPHBH) in the presence of Triton X-100. The molar absorptivity and Sandell’s sensitivity of the coloured species at pH 4.4 were found to be 4.20 x 104 L mol-1 cm-1 and 5.5 ng cm-2, respectively. Beer’s law is obeyed in the range 0.35 -3.8 g mL-1 of thorium(IV) at 410 nm. The stoichiometry of the complex was found to be 1:2 (Th(IV): DMPHBH). A highly selective first order derivative spectrophotometric method for the determination of thorium in the presence of uranium is also reported. The detection limit and quantitation limit of first order derivative spectrophotometry were found to be 0.03 and 0.11 g mL-1, respectively. The developed procedure has been successfully applied for the trace level determination of thorium in rock samples and synthetic mixtures

Transition to the ultimate regime in two-dimensional Rayleigh-B\'enard convection

The possible transition to the so-called ultimate regime, wherein both the bulk and the boundary layers are turbulent, has been an outstanding issue in thermal convection, since the seminal work by Kraichnan [Phys. Fluids 5, 1374 (1962)]. Yet, when this transition takes place and how the local flow induces it is not fully understood. Here, by performing two-dimensional simulations of Rayleigh-B\'enard turbulence covering six decades in Rayleigh number Ra up to $10^{14}$ for Prandtl number Pr $=1$, for the first time in numerical simulations we find the transition to the ultimate regime, namely at $\textrm{Ra}^*=10^{13}$. We reveal how the emission of thermal plumes enhances the global heat transport, leading to a steeper increase of the Nusselt number than the classical Malkus scaling $\textrm{Nu} \sim \textrm{Ra}^{1/3}$ [Proc. R. Soc. London A 225, 196 (1954)]. Beyond the transition, the mean velocity profiles are logarithmic throughout, indicating turbulent boundary layers. In contrast, the temperature profiles are only locally logarithmic, namely within the regions where plumes are emitted, and where the local Nusselt number has an effective scaling $\textrm{Nu} \sim \textrm{Ra}^{0.38}$, corresponding to the effective scaling in the ultimate regime.Comment: 6 pages, 4figure

Theoretical Study of Irradiation Effects in Close Binaries

The effect of irradiation is studied in a close binary systemassuming that the secondary component is a point source, moving in a circularorbit. The irradiation effects are calculatedon the atmosphere of the primary component in a 3-dimensional Cartesiancoordinate geometry. In treating the reflection effect theoretically, the totalradiation $(S_mathrm{T})$ is obtained as the sum of the radiation of 1) the effect ofirradiation on the primary component which is calculated by using onedimensional rod model $(S_mathrm{r})$ and 2) the self radiation of the primarycomponent which is calculated by using the solution of radiative transferequation in spherical symmetry $(S_mathrm{s})$. The radiation field is estimated alongthe line of sight of the observer at infinity. It is shown how the radiationfield changes depending on the position of the secondary component

A Comparative Study of the Mechanical Properties of Single and Double Sided Friction Stir Welded Aluminium Joints

AbstractAluminium alloys have a wide range of application in many key industries like aerospace and defence. It is necessary to have a high strength joint without much distortion in the above applications. In the present investigation, Al 1100 H14 aluminum alloy strips were joined by friction stir welding (FSW) process by single and double sided welding. Also the effect of direction of welding on tensile properties of the joints was investigated. Standard thickness (4mm) aluminium pieces were joined by FSW under various traversing speeds and rotational speeds. The effects on mechanical properties like surface hardness and tensile strength of the welded region were studied. It has been concluded that double sided welds are better in strength compared to single sided ones and same direction welds have substantial improvement in mechanical properties when compared to opposite direction ones

Systematic review of patient factors affecting adipose stem cell viability and function: implications for regenerative therapy

Background: The applications for fat grafting have increased recently, within both regenerative and reconstructive surgery. Although fat harvesting, processing and injection techniques have been extensively studied and standardised, this has not had a big impact on the variability of outcome following fat grafting. This suggests a possible larger role of patient characteristics on adipocyte and adipose-derived stem cell (ADSC) viability and function. This systematic review aims to collate current evidence on the effect of patient factors on adipocyte and ADSC behaviour. Methods: A systematic literature review was performed using MEDLINE, Cochrane Library and EMBASE. It includes outcomes observed in in vitro analyses, in vivo animal studies and clinical studies. Data from basic science work have been included in the discussion to enhance our understanding of the mechanism behind ADSC behaviour. Results: A total of 41 papers were included in this review. Accumulating evidence indicates decreased proliferation and differentiation potential of ADSCs with increasing age, body mass index, diabetes mellitus and exposure to radiotherapy and Tamoxifen, although this was not uniformly seen across all studies. Gender, donor site preference, HIV status and chemotherapy did not show a significant influence on fat retention. Circulating oestrogen levels have been shown to support both adipocyte function and graft viability. Evidence so far suggests no significant impact of total cholesterol, hypertension, renal disease, physical exercise and peripheral vascular disease on ADSC yield. Conclusions: A more uniform comparison of all factors highlighted in this review, with the application of a combination of tests for each outcome measure, is essential to fully understand factors that affect adipocyte and ADSC viability, as well as functionality. As these patient factors interact, future studies looking at adipocyte viability need to take them into consideration for conclusions to be meaningful. This would provide crucial information for surgeons when deciding appropriate volumes of lipoaspirate to inject, improve patient selection, and counsel patient expectations with regards to outcomes and likelihood for repeat procedures. An improved understanding will also assist in identification of patient groups that would benefit from graft enrichment and cryopreservation techniques

Preliminary report on a reconnaissance survey of the major coastal and marine ecosystems in Gulf of Kutch

The region of Gulf of Kutch was possibly more an arid zone in the pleistocene, almost approaching to a desert condition, than what it is at present. The gulf is believed to be the result of a wide indentation or subsidence that allowed encroachment of the sea in the geological past. The whole area is still supposed to be seismically unstable. The Gulf of Kutch covers an area of circa 7,350 sq. km with a maximum depth of 60 m. The tidal range varies from 3.06 to 5.89 m with an average of 4 m. The intertidal zones are sandy and muddy or with sandstones of vast expanse and prolonged exposure