Giant Tunneling Magnetoresistance, Glassiness, and the Energy Landscape at Nanoscale Cluster Coexistence

We present microscopic results on the giant tunneling magnetoresistance that arises from the nanoscale coexistence of ferromagnetic metallic (FMM) and antiferromagnetic insulating (AFI) clusters in a disordered two dimensional electron system with competing double exchange and superexchange interactions. Our Monte Carlo study allows us to map out the different field regimes in magnetotransport and correlate it with the evolution of spatial structures. At coexistence, the isotropic O(3) model shows signs of slow relaxation, and has a high density of low energy metastable states, but no genuine glassiness. However, in the presence of weak magnetic anisotropy, and below a field dependent irreversibility temperature $T_{irr}$, the response on field cooling (FC) differs distinctly from that on zero field cooling (ZFC). We map out the phase diagram of this `phase coexistence glass', highlight how its response differs from that of a standard spin glass, and compare our results with data on the manganites.Comment: Final published versio

An Algorithm to Generate Classical Solutions for String Effective Action

It is shown explicitly, that a number of solutions for the background field equations of the string effective action in space-time dimension D can be generated from any known lower dimensional solution, when background fields have only time dependence. An application of the result to the two dimensional charged black hole is presented. The case of background with more general coordinate dependence is also discussed.Comment: 12 page

Power Quality Improvement Wind Energy System Using Cascaded Multilevel Inverter

In this paper, a wind energy conversion system based on a cascaded H-bridge multilevel inverter (CHBMLI) topology has been proposed to be used for the grid interface of large split winding alternators (SWAs). A new method has been suggested for the generation of reference currents for the voltage source inverter (VSI) depending upon the available wind power. The CHBMLI has been used as a VSI and operated in a current control mode order to achieve the objectives of real power injection and load compensation (power factor correction, load balancing, and harmonic compensation) based on the proposed reference generation scheme. In the field excitation control of SWA provides a single means vary the dc link voltages of all the CHBs simultaneously and proportionatel

Blood pressure response to Cold Pressor Test in the children of hypertensives

Two hundred student volunteers of 16-24 yrs were divided into two groups of 100 each, as children of hypertensive and children of normotensive parents. It was observed that there was no difference in resting SBP and DBP in both groups before CPT. After CPT, significant higher values of SBP after immersion, DBP after immersion, difference of SBP and difference of DBP were observed in children of hypertensive parents as compared to children of normotensive parents. This study can be used as a predictor of future development of hypertension for which early preventive measures can be taken to reduce the morbidity and mortality due to hypertensive complications

Higher rank Wilson loops from a matrix model

We compute the circular Wilson loop of N=4 SYM theory at large N in the rank k symmetric and antisymmetric tensor representations. Using a quadratic Hermitian matrix model we obtain expressions for all values of the 't Hooft coupling. At large and small couplings we give explicit formulae and reproduce supergravity results from both D3 and D5 branes within a systematic framework.Comment: 1+18 pages. 1 figure. Typos correcte

Measurement of triple differential photon plus jet cross section by D0

We report on a new measurement of triple differential cross section for the process ppbar -> photon + jet + X in ppbar collisions at sqrt(s)=1.96 TeV by the D0 Collaboration at Fermilab based on a dataset corresponding to an integrated luminosity of 1.1 fb-1.Comment: 3 pages, 1 figure, To appear in the Proceedings of the 2007 Europhysics Conference on High Energy Physics, Manchester, UK. Accepted for publication in Journal of Physics : Conference Serie

DSDV, DYMO, OLSR: Link Duration and Path Stability

In this paper, we evaluate and compare the impact of link duration and path stability of routing protocols; Destination Sequence Distance vector (DSDV), Dynamic MANET On- Demand (DYMO) and Optimized Link State Routing (OLSR) at different number of connections and node density. In order to improve the efficiency of selected protocols; we enhance DYMO and OLSR. Simulation and comparison of both default and enhanced routing protocols is carried out under the performance parameters; Packet Delivery Ratio (PDR), Average End-to End Delay (AE2ED) and Normalized Routing Overhead (NRO). From the results, we observe that DYMO performs better than DSDV, MOD-OLSR and OLSR in terms of PDR, AE2ED, link duration and path stability at the cost of high value of NRO

Waves on Noncommutative Spacetimes

Waves on ``commutative'' spacetimes like R^d are elements of the commutative algebra C^0(R^d) of functions on R^d. When C^0(R^d) is deformed to a noncommutative algebra {\cal A}_\theta (R^d) with deformation parameter \theta ({\cal A}_0 (R^d) = C^0(R^d)), waves being its elements, are no longer complex-valued functions on R^d. Rules for their interpretation, such as measurement of their intensity, and energy, thus need to be stated. We address this task here. We then apply the rules to interference and diffraction for d \leq 4 and with time-space noncommutativity. Novel phenomena are encountered. Thus when the time of observation T is so brief that T \leq 2 \theta w, where w is the frequency of incident waves, no interference can be observed. For larger times, the interference pattern is deformed and depends on \frac{\theta w}{T}. It approaches the commutative pattern only when \frac{\theta w}{T} goes to 0. As an application, we discuss interference of star light due to cosmic strings.Comment: 19 pages, 5 figures, LaTeX, added references, corrected typo