Study on Noncommutative Representations of Galilean Generators

The representations of Galilean generators are constructed on a space where both position and momentum coordinates are noncommutating operators. A dynamical model invariant under noncommutative phase space transformations is constructed. The Dirac brackets of this model reproduce the original noncommutative algebra. Also, the generators in terms of noncommutative phase space variables are abstracted from this model in a consistent manner. Finally, the role of Jacobi identities is emphasised to produce the noncommuting structure that occurs when an electron is subjected to a constant magnetic field and Berry curvature.Comment: Title changed, new references added, published in Int. J. Mod. Phys.

Evaluation of seeding rates of rice nursery on seedling vigour and its effect on crop productivity under system of rice intensification

Four seeding rates (25, 30, 35 and 40 g/m2) of rice in nursery were tested for seedling vigour recorded at 10, 17 and 24 DAS at Malan during 2013 and 2014. The seedling vigour so obtained in nursery was subsequently evaluated in field during kharif 2013. Thus twenty four treatments comprised of combinations of three seedling ages (10, 17 and 24 days) and two spacings (20 × 20 cm and 20 × 15 cm) in main plots and four seedling vigour from four seeding rates (25, 30, 35 and 40 g/m2) in sub plots were evaluated in split plot design. Seedling shoot length under all seeding rates (25-35 g/m2) was significantly higher compared to check (40 g/m2) during 2013. In the next year, shoot and root length (30-35 g/m2), tiller per seedling and leaves per seedling (25-30 g/m2) of 24 days nursery was significantly higher over check (40 g/m2). Plant height, tillers, leaves and dry matter accumulation were significantly higher when younger seedlings aged 10 and 17 days were used. The crop raised using 10 days old seedlings matured 3-5 days earlier than 24 days old seedlings. Wider spacing resulted in more plant height, tillers, leaves and dry matter accumulation. Seedlings from 25, 30 and 35 g seed/m2 resulted in significantly taller plants than 40 g/m2. The seeding rate, seedling age and plant spacing did not significantly influence rice productivity thereby permitting flexibility to the rice farmers in the adoption of these factors

Current trends and future of sequential micro-machining processes on a single machine tool

A sequential micro-machining process chain is described as the machining strategy whereby two or more micro-machining techniques are implemented in sequence on same or different machine tools. This is in contrast to hybrid micro-machining where two standalone machining technologies are integrated together. A recent surge of interest is geared towards building sequential micro-machining capabilities on a single machine tool to avoid realignment and registration errors between processes. One of the major advantages of performing sequential micro-machining on a single machine tool is that it suppresses repositioning errors so enabling much higher levels of accuracy (and thereby tighter tolerances), reduced rejection of machined components, and lower production time; all of these would be otherwise unachievable. Thus, multifunctional micro-machining centres are attracting global interest. Clearly, the necessity of developing reconfigurable, precise and flexible manufacturing is a key driver to this trend. This review aims to provide a critical insight into the recent trends and new classification of sequential micro-machining processes with a special focus on evaluation of such capabilities built on a single machine tool and further potentials. The machining capabilities, advantages and opportunities in the area of sequential micro-machining techniques are evaluated thoroughly and the directions for future work are highlighted

Lagrangian generators of the Poincare gauge symmetries

We have systematically computed the generators of the symmetries arising in Poincare gauge theory formulation of gravity, both in 2+1 and 3+1 dimensions. This was done using a completely Lagrangian approach. The results are expected to be valid in any dimensions, as seen through lifting the results of the 2+1 dimensional example into the 3+1 dimensional one.Comment: Latex2e, 15 pages, 1 figure; (v2) Appendix containing discussion on applications of Lagrangian generators adde

Noncommutative Black Hole Thermodynamics

We give a general derivation, for any static spherically symmetric metric, of the relation $T_h=\frac{\cal K}{2\pi}$ connecting the black hole temperature ($T_h$) with the surface gravity ($\cal K$), following the tunneling interpretation of Hawking radiation. This derivation is valid even beyond the semi classical regime i. e. when quantum effects are not negligible. The formalism is then applied to a spherically symmetric, stationary noncommutative Schwarzschild space time. The effects of back reaction are also included. For such a black hole the Hawking temperature is computed in a closed form. A graphical analysis reveals interesting features regarding the variation of the Hawking temperature (including corrections due to noncommutativity and back reaction) with the small radius of the black hole. The entropy and tunneling rate valid for the leading order in the noncommutative parameter are calculated. We also show that the noncommutative Bekenstein-Hawking area law has the same functional form as the usual one.Comment: LaTex, 17 pages, 2 figures, minor changes, references added, to appear in Phys. Rev.

A Gyrochronology and Microvariability Survey of the Milky Way's Older Stars Using Kepler's Two-Wheels Program

Even with the diminished precision possible with only two reaction wheels, the Kepler spacecraft can obtain mmag level, time-resolved photometry of tens of thousands of sources. The presence of such a rich, large data set could be transformative for stellar astronomy. In this white paper, we discuss how rotation periods for a large ensemble of single and binary main- sequence dwarfs can yield a quantitative understanding of the evolution of stellar spin-down over time. This will allow us to calibrate rotation-based ages beyond ~1 Gyr, which is the oldest benchmark that exists today apart from the Sun. Measurement of rotation periods of M dwarfs past the fully-convective boundary will enable extension of gyrochronology to the end of the stellar main-sequence, yielding precise ages ({\sigma} ~10%) for the vast majority of nearby stars. It will also help set constraints on the angular momentum evolution and magnetic field generation in these stars. Our Kepler-based study would be supported by a suite of ongoing and future ground-based observations. Finally, we briefly discuss two ancillary science cases, detection of long-period low-mass eclipsing binaries and microvariability in white dwarfs and hot subdwarf B stars that the Kepler Two-Wheels Program would facilitate.Comment: Kepler white pape