Search Results - (Author, Cooperation:G. Gupta)

2018-01-25

American Physical Society (APS)

0556-2813

1089-490X

Physics

Nuclear Structure

2018-02-13

Wiley-Blackwell

0007-0963

1365-2133

Medicine

2018-03-12

Wiley-Blackwell

0007-0963

1365-2133

Medicine

2015-01-31

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2018-04-05

Institute of Physics (IOP)

1757-8981

1757-899X

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

2018-10-12

American Physical Society (APS)

0556-2813

1089-490X

Physics

Nuclear Structure

1089-7674

AIP Digital Archive

Physics

Electronic Resource

1089-7674

AIP Digital Archive

Physics

Theoretical profiles of power reflectivity of a phase conjugate electromagnetic wave generated by nearly degenerate four-wave mixing in a carbon plasma via parametric decay instability (PDI) are studied. The plasma is considered to be produced by irradiating a carbon slab target with an Nd:glass high-power laser pulse at an intensity above the PDI threshold. The plasma refractive index corresponding to the PDI region is taken into account in the wave equations. Two electromagnetic pump waves counterpropagating in the plasma are Nd:glass laser light waves and a weak electromagnetic probe wave incident upon the plasma, which is very slightly frequency upshifted relative to the pump waves. The effects of the frequency and angular detuning between the pump and probe waves, pump wave intensity, and plasma parameters on the reflectivity profiles have been investigated. It is noted that the plasma refractive index significantly affects the reflectivity profiles of the phase conjugate wave. © 1996 American Institute of Physics.

Electronic Resource

1089-7674

AIP Digital Archive

Physics

Accounting for both the long- and short-wavelength density gratings by considering the polarizations of all four electromagnetic waves parallel to each other and a finite tilt angle between the signal and pump waves, the steady-state phase conjugation in the low reflectivity regime by nearly degenerate four-wave mixing in a homogeneous plasma is investigated. The response of the density gratings caused by the beating of the signal and pump waves is considered from the theory of stimulated Brillouin scattering in a two-component plasma. The expression for the power reflectivity of the conjugate wave for the arbitrary difference frequency between the signal and pump waves and that for resonant four-wave mixing are obtained. Numerical results have been discussed in light of the experiment reported in the literature. It is noted that the measured values of the difference frequency corresponding to either density grating resonance, and the corresponding maximum reflectivity of the conjugate wave, provide a diagnostic tool for the electron temperature and the electron–ion temperature ratio, respectively. © 1998 American Institute of Physics.

Electronic Resource

1089-7674

AIP Digital Archive

Physics

Convective stimulated Brillouin scattering (SBS) in the directly backward direction of the obliquely incident laser light in an expanding and inhomogeneous laser plasma is studied. Accounting for the thermal motion of both electrons and ions of the plasma in the dispersion relation of the ion-acoustic wave, the expression of the convective SBS gain coefficient is derived in the weak coupling limit. The behavior of the gain with the angle of incidence of the laser irradiation in a laser-produced CH plasma is investigated by considering various plasma and laser conditions in light of the reported laser-plasma experiment with the 0.35 μm laser irradiating the CH target. The results are observed to be significantly different from those for normal incidence. © 1997 American Institute of Physics.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract: The levels of epinephrine, norepinephrine, and dopamine and the activities of tyrosine hydroxylase and monoamine oxidase were estimated in four regions of rat brain during alloxan-induced hyperglycemia and insulin-induced hypoglycemia. Catecholamine levels were estimated by HPLC, and the insulin levels were quantified by radioimmunoassay. The results demonstrated significant increases in the activities of the metabolizing enzymes and levels of catecholamines during experimental conditions. The levels of catecholamines were highest in the cerebral hemispheres, the region associated with high activities of the metabolizing enzymes. Insulin-induced hypoglycemia caused a decrease in the activities of the metabolizing enzymes followed by their recovery within 2 h.

Electronic Resource

1365-2230

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Summary Viral warts are the most common disease of the skin and are caused by human papillomavirus (HPV). Plantar warts, a manifestation of infection by HPV-1, -2 and -4, tend to be smoother and flatter than common warts and can also be painful when pressure is applied. A variety of local treatments, including topical salicyclic acid, cryotherapy, topical 5-fluorouracil, intralesional interferons and photodynamic therapy, are available to treat plantar warts. Here we report two cases of plantar warts, which had been previously treated without success. Total clearance of the warts was observed in both cases after treatment with imiquimod 5% cream over a period of 12 weeks. No evidence of local skin reactions was observed in either case during the treatment period. Recurrent lesions were not evident in the follow-up period for each patient.

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The efficacy of narrowband ultraviolet B (UVB) was assessed in 100 consecutive patients with psoriasis by quantifying disease severity using objective (Psoriasis Area and Severity Index, PASI and Dermatologists Global Assessment, DGA) and subjective (Psoriasis Disability Index, PDI) measures. The median pretreatment PASI, DGA and PDI were 5.7 (interquartile range, IQR 4.5–8.35), 7 (IQR 6–9) and 42 (IQR 29–63.5), respectively. At 3 month follow-up, the PASI, DGA and PDI had fallen to 2.7 (IQR 1.1–3.5), 3 (IQR 2–5) and 30 (IQR 21–50.5), respectively (P 〈 0.001). A small group of patients continued to score highly on their PDI despite being clinically clear or having minimal disease, possibly representing chronic disability behaviour. Patients exhibiting this may require more intensive supervision. In most patients, symptoms of itch and pain improved or disappeared (70% and 75%, respectively). Side-effects were reported in 18%. Narrowband UVB phototherapy is safe and effective for psoriasis. Symptoms and subjective quality of life measures improved significantly. Both objective and subjective measures should be used when evaluating the efficacy of a treatment for psoriasis.

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1089-7550

AIP Digital Archive

Physics

X-ray laser gain in laser-produced plasmas for collisionally pumped 3p-3s transitions in neon (Ne)-like krypton ions has been estimated. The dependence of the gain on the temperature-dependent average ionic charge state Z¯(Te) and the fraction δ(Te) of Ne-like ions evaluated by using the plasma ionization model has been studied. It is observed that the temperature dependence of these parameters has a profound effect on the gain estimate, showing the importance of including the ionization model precisely for accurate modeling of x-ray laser gain. © 1995 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The fraction of neonlike ions and the average ionic charge state in laser plasmas formed at the surface of the solid targets of germanium, selenium, and krypton have been obtained at several electron temperatures using the steady-state collisional radiative ionization model. Dielectronic recombination has been considered. The effect of consideration of dielectronic recombination of ions of one or more charge states on these parameters has been studied. It is observed that the values of electron temperature corresponding to the maximum abundance of neonlike ions in different cases of dielectronic recombination are significantly different from those obtained without consideration of dielectronic recombination. The optimum electron temperature of the plasma is estimated from the maximization of the x-ray laser gain through temperature-dependent variables of the gain coefficient and is observed to be the electron temperature at which the abundance of neonlike ions is maximum. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The values of the effective scattering angle 〈θ〉 of a relativistic electron beam injected through an anode foil are analyzed by different methods in the light of reported values for various beam-plasma heating experiments. Wide variations in calculated 〈θ〉 are noted depending on the method used. It is argued that the 〈θ2〉1/2 expression corrected for Molière screening and the (1/e) equivalent from the Monte Carlo code give nearly the same average scattering angle and one of them should be used to determine 〈θ〉. It is also seen that a small variation in 〈θ〉 alters significantly the plasma temperature estimate.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The current multiplication observed when a relativistic electron beam is propagated in an initially neutral gas at subTorr pressures (0.1–0.3 Torr) is generally attributed to the two-stream instability. A general expression for this current gain is derived for a scattered beam propagating in a neutral gas, which takes into account a quasihydrodynamic expression for the beam energy loss. Moreover, the beam-to-plasma density ratio is obtained as a function of time for a given beam pulse by numerically solving the electron energy and continuity equations. It is found that at a given beam-to-plasma density ratio, the current gain increases with increasing the beam energy, with the increase being most rapid for the small scattering angles. A finite average scattering angle is seen to reduce the current multiplication. The experimentally observed peak current gains are in good agreement with the predicted peak gains obtained by taking into account the time-evolved beam-to-plasma density ratio.

Electronic Resource