MRI of the brain in patients with miliary pulmonary tuberculosis without symptoms or signs of central nervous system involvement

MRI was performed on patients with miliary pulmonary tuberculosis to look for brain involvement and to study the features sequentially, during treatment. We studied seven patients with typical radiographic tuberculosis, and no symptoms or signs of central nervous system involvement. Conventional spin-echo (SE) imaging, including contrast enhanced images, was performed in all cases. All patients showed brain involvement: four patients showed lesions mainly less than 3 mm in diameter, better seen on contrast-enhanced images. These patients showed oedema around the lesions after 2 months of treatment, with subsequent regression on follow-up. The remaining three patients had multiple lesions, 3 mm or more in diameter, which showed a gradual decrease on follow-up. We conclude that the brain may commonly be involved in miliary pulmonary tuberculosis. The response to treatment depends on the stage of the granuloma and shows a definite pattern of healing on follow-up.     

On the steady flow produced in fluid-particle suspension by an infinite rotating disk with surface suction

The steady flow of a fluid-particle suspension over an infinite rotating disk with uniform suction is considered. The equations of motion are reduced to ordinary differential equations by similarity transformations and solved numerically by using a least-squares finite-element method. Some typical results for both fluid and particle phases and density distributions of the particles are presented graphically for the suction parameter A = 3.0 in order to illustrate some interesting features of the solutions. It is observed that the radial velocity of the particle attains its maximum on the surface of the disk and the particles slip in the tangential direction on the disk. The magnitudes of the radial velocity components of both the fluid and particle phases are found to decrease rapidly as suction increases.     

A Differential CMOS Current-Mode Variable Gain Amplifier with Digital dB-Linear Gain Control

A novel CMOS variable gain amplifier operating on current signals with a dB-linear gain control is presented. The gain control is achieved by multiplying a digitally synthesized exponentially varying control current signal by a differential input signal in the current domain. A current amplifier at the output sets the gain to the desired level. Current-mode operation allows for a reduced supply voltage by minimizing the voltage swing at the low impedance nodes of the circuit. Multiple circuit realizations for various blocks are presented allowing for designs meeting different constraints. Experimental realization of the variable gain amplifier shows the validity of the presented approach.     

Analysis of the stress-strain curves of a modified 9Cr-1Mo steel by the voce equation

The representation of stress-strain curves by empirical relations can give first-hand information on the deformation behavior of a material. Although the constants in these equations are simple numerals for smooth fitting of the curves, a theoretical basis using dislocation interaction has been out forth bv Berastrom.[1]     

A CMOS RF front-end for a multistandard WLAN receiver

This letter describes the design and performance of a dual band tri-mode receiver front-end compliant with the IEEE 802.11a, b, and g standards. The receiver front-end was built in a 0.18-/spl mu/m CMOS process and achieves a noise figure of 4.7 dB/5.1 dB for the 2.4-GHz/5-GHz bands, respectively. The receiver front-end provides a dual gain mode of 5 dB/30 dB with an IIP3 of -1dBm for the low gain mode. The front-end draws 25 mA/27 mA from a 1.8-V supply for the 2.4-GHz/5-GHz bands, respectively.     

Some aspects of dislocation-precipitate interaction in under-aged aluminium-germanium alloy

The glide dislocation-precipitate interaction in under-aged alloy is investigated by microscopy and low-temperature deformation techniques. Slip-line features of room temperature deformed samples were observed by optical microscopy. From tensile tests at various temperatures the variation of flow stress withT ^2/3 was established. Comparing the present results with those obtained on the peak-hardened condition of the same alloy it is concluded that moving dislocation shear through the small rod-shaped germanium precipitates.     

Storage stability of solid rocket fuels. 2. Effect of oxidizer loadings

Ageing behaviour, leading to ballistic changes, has been studied as a function of oxidizer loading in polystyrene/ammonium perchlorate solid-propellants. The ageing studies were carried out at 100 °C in air. Change in burning rate decreased as the oxidizer loading increased from 75 to 80%. The change in thermal decomposition rates both at 230 and 260 °C also decreased as the oxidizer loading in the propellants increased. The shapes of the plots of the changes in burning rate and thermal decomposition rate (230 and 260 °C) at different storage times for different oxidizer-loaded propellants seem to be exactly similar. These results lead to the conclusion that the thermal decomposition of the propellant may be responsible for bringing about the ballistic changes during the ageing process. Infrared studies of the binder portion of the aged propellant indicate that peroxide formation takes place during the course of ageing and that peroxide formation for a particular storage time and temperature increases as the loading decreases.     

Transmission parameters of a class of coupled distributed networks

It is shown how the equations of a class of coupled distributed networks can be decoupled, and their transmission parameters expressed in terms of those of an equivalent scalar system.