Global Optimization Of Quasi-Monoenergetic Electron Beams From Laser Wakefield Accelerators

We globally optimize a terawatt-laser-driven wakefield accelerator by systematically varying laser and target parameters to achieve 100 MeV electrons, 10% energy spread, 100 pC charge, 4 mrad divergence and 10 mrad pointing fluctuation with similar to 100% reproducibility, thereby meeting conditions for producing similar to 10(6) 200 keV X-ray photons/pulse by inverse Compton scatter.Physic

Zero Temperature Insulator-Metal Transition in Doped Manganites

We study the transition at T=0 from a ferromagnetic insulating to a ferromagnetic metallic phase in manganites as a function of hole doping using an effective low-energy model Hamiltonian proposed by us recently. The model incorporates the quantum nature of the dynamic Jahn-Teller(JT) phonons strongly coupled to orbitally degenerate electrons as well as strong Coulomb correlation effects and leads naturally to the coexistence of localized (JT polaronic) and band-like electronic states. We study the insulator-metal transition as a function of doping as well as of the correlation strength U and JT gain in energy E_{JT}, and find, for realistic values of parameters, a ground state phase diagram in agreement with experiments. We also discuss how several other features of manganites as well as differences in behaviour among manganites can be understood in terms of our model.Comment: To be published in Europhysics Letter

Chondroid Syringoma and Eccrine Spiradenoma

Fine needle aspiration cytology (FNAC) is a well established diagnostic tool. However, most clinicians prefer to diagnose suspected skin tumors by excisional biopsy as they are easily accessible and hence benign skin adnexal tumors are rarely encountered on FNAC. There are only a very few case reports describing the fine needle aspiration cytologic features of chondroid syringoma and eccrine spiradenoma for diagnosis. Cases: First case was a 20 year old female who presented with firm,non-tender swelling in the left little finger measuring 1 cm in diameter. Smears showed clusters of round to plasmacytoid cells with moderate to abundant cytoplasm embedded in a chondromyxoid ground substance . Hence, a diagnosis of chondroid syringoma was made. Another case was a 40 year old lady who presented with a painful swelling on the anterior chest wall measuring approximately 0.8 cms in diameter. Smears were moderately cellular with cohesive sheets and clusters of bland cells of three different cell types. Hence, a probable diagnosis of eccrine spiradenoma was made and both the cases were confirmed histologically. Conclusion: Appropriate knowledge of the cytologic features of chondroid syringoma and eccrine spiradenoma helps in providing a definitive diagnosis and correct management of the patient

MEMS-based hemispherical resonator gyroscopes

pre-printThis paper introduces a fabrication technique that uses planar MEMS micromachining processes to produce hemispherical resonating shells for gyroscopes. The hemispheres exhibit a quality factor in excess of 20,000 with resonant frequencies in the range of 20 kHz for the 4-node wineglass mode. The fabrication process enables production of almost perfect hemispheres (less than 1% asphericity near the pedestal) with an average surface roughness of 5nm. The high degree of sphericity contains the relative frequency mismatch Δf/f between the two degenerate modes to 0.02%. Simplicity of the fabrication process and the successful testing of the drive/sense mechanism in the resonator make it a good candidate for use as gyroscopes