High contrast optical modulation by surface acoustic waves

Numerical Calculations are employed to study the modulation of light by surface acoustic waves (SAWs) in photonic band gap (PBG) structures. The on/off contrast ratio in PBG switch based on optical cavity is determined as a function of the SAW induced dielectric modulation. We show that these structures exhibit high contrast ratios even for moderate acousto-optic couplingComment: 7 manuscript pages and 5 figures; submitted to Applied Physics Letters on April 24, 200

The response of the upper atmospheric temperature to changes in solar EUV radiation and geomagnetic activity

Solar radiation and magnetic effects on upper atmospheric neutral temperatures derived from satellite dra

Doping and Field-Induced Insulator-Metal Transitions in Half-Doped Manganites

We argue that many properties of the half-doped manganites may be understood in terms of a new two-(eg electron)-fluid description, which is energetically favorable at intermediate Jahn-Teller (JT) coupling. This emerges from a competition between canting of the core spins of Mn promoting mobile carriers and polaronic trapping of carriers by JT defects, in the presence of CE, orbital and charge order. We show that this explains several features of the doping and magnetic field induced insulator-metal transitions, as the particle-hole asymmetry and the smallness of the transition fields.Comment: 4 pages, 4 figure

Dismissal Laws, Innovation and Economic Growth

I theoretically and empirically show that dismissal laws - laws that impose hurdles on firing of employees - spur innovation and thereby economic growth. Theoretically, dismissal laws make it costly for firms to arbitrarily discharge employees. This enables firms to commit to not punish short-run failures of employees. Because innovation is inherently risky and employment contracts are incomplete, dismissal laws enable such commitment. Specifically, absent such laws, firms cannot contractually commit so ex-ante. The commitment provided by dismissal laws encourages employees to exert greater effort in risky, but path-breaking, projects thereby fostering firm-level innovation. I provide empirical evidence supporting this thesis using the discontinuity provided by the passage of the federal Worker Adjustment and Retraining Notification Act. Using the fact that this Act only applied to firms with 100 or more employees, I undertake difference-in-difference and regression discontinuity tests to provide this evidence. Building on endogenous growth theory, which posits that economic growth stems from innovation, I also show that dismissal laws correlate positively with economic growth. However, other forms of labor laws correlate negatively with economic growth and swamp the positive effect of dismissal laws

Complementary two-way algorithms for negative radix conversions

This paper describes two sets of algorithms in positive radix arithmetic for conversions between positive and negative integral radix representation of numbers. Each set consists of algorithms for conversions in either direction; these algorithms are mutually complementary in the sense they involve inverse operations depending upon the direction of conversion. The first set of algorithms for conversion of numbers from positive to negative radix (negative to positive radix) proceeds serially from the least significant end of the number and involves complementation and addition (subtraction) of unity on single-digit numbers. The second set of algorithms for conversion of numbers from positive to negative radix (negative to positive radix) proceeds in parallel starting from the full number (the most significant end of the number) and involves complementation and right (left) shift operations. The applications of these algorithms to integers, mixed integer-fractions, floating-point numbers, and for real-time conversions are given

Self-organization and autonomy in computational networks: agents-based contractual workflow paradigm

We describe an agents-based contractual workflow paradigm for Self-organization and autonomy in computational networks. The agent-based paradigm can be interpreted as the outcome arising out of deterministic, nondeterministic or stochastic interaction among a set of agents that includes the environment. These interactions are like chemical reactions and result in self-organization. Since the reaction rules are inherently parallel, any number of actions can be performed cooperatively or competitively among the subsets of elements, so that the agents carry out the required actions. Also we describe the application of this paradigm in finding short duration paths, chemical- patent mining, and in cloud computing services

Instabilities and Insulator-Metal transitions in Half-Doped Manganites induced by Magnetic-Field and Doping

We discuss the phase diagram of the two-orbital model of half-doped manganites by calculating self-consistently the Jahn-Teller (JT) distortion patterns, charge, orbital and magnetic order at zero temperature. We analyse the instabilities of these phases caused by electron or hole doping away from half-doping, or by the application of a magnetic-field. For the CE insulating phase of half-doped manganites, in the intermediate JT coupling regime, we show that there is a competition between canting of spins (which promotes mobile carriers) and polaronic self-trapping of carriers by JT defects. This results in a marked particle-hole asymmetry, with canting winning only on the electron doped side of half-doping. We also show that the CE phase undergoes a first-order transition to a ferromagnetic metallic phase when a magnetic-field is applied, with abrupt changes in the lattice distortion patterns. We discuss the factors that govern the intriguingly small scale of the transition fields. We argue that the ferromagnetic metallic phases involved have two types of charge carriers, localised and band-like, leading to an effective two-fluid model.Comment: 22 pages, 28 figure