Comparison of BJT and MESFET front ends in broadband optical transimpedance preamplifiers

We show in this paper that little noise penalty is incurred by using readily available bipolar junction transistors in place of GaAs MESFETs in the first stage of high-speed optical transimpedance preamplifiers.     

Kinetics of the reaction of hydroxyl radicals with 2-(dimethylamino)ethanol from 234–364 K

The temperature dependence of the rate of the reaction of OH with 2-(dimethylamino)-ethanol, (CH₃)₂NCH₂CH₂OH (DMAE) was investigated over the temperature range, 234 to 364 K. The reaction was studied using the flash photolysis-resonance fluorescence technique. The room temperature rate constant determined for this reaction was (10.3 ± 2.0) × 10^?11 cm³ molecule^?1 s^?1, with essentially no temperature dependence evident within the uncertainty in the experiments. A value of (9.0 ± 2.0) × 10^?11 cm³ molecule^?1 s^?1 is believed to best describe the reaction over the entire temperature range. The room temperature rate constant is about twice the value reported previously for this reaction. The overall reaction of OH with DMAE was apportioned to the reactivity of OH for abstracting individual H- atoms from different types of C? H bonds and the O? H bond within the molecule. This technique predicts the overall rate constant for the OH-DMAE reaction to within about 15% of the experimental value and makes it possible to estimate the yields of the initial radical products of the OH attack on DMAE. A mechanism is proposed for the subsequent atmospheric reactions that would occur in the photooxidation of DMAE.     

Some observations on the interdependence of cyanide concentration and atomization efficiency in the nitrous oxide-acetylene flame

A relationship is derived between CN concentration and atomization efficiency in the C₂H₂-N₂O flame. The relationship is examined under various experimental conditions and β values are estimated for a number of elements. The possibility of complex vapour phase oxide formation by U is considered.     

On the existence of the Galactic Radio Halo

Radio astronomical data available on the galactic background radiation has been carefully examined to deduce information on the existence or otherwise of a Galactic Radio Halo. It is shown that, though considerable doubt has been recently expressed by some regarding its existence, no convincing and quantitative reasoning has been so far advanced towards this; on the other hand, there are substantial arguments in its favour.     

Transition quadrupole moments of superdeformed states in194Pb

Lifetimes of superdeformed states in¹⁹⁴Pb were measured by the Doppler-shift attenuation method. Quadrupole moments around 20 eb, that are constant over the observed frequency range, are derived. The results rule out large centrifugal stretching effects.     

An estimate of the secondary-proton spectrum at small atmospheric depths

Summary We have calculated the energy spectrum of secondary protons produced in the atmosphere as a function of the atmospheric depth and zenith angles at a location with zero geomagnetic cut-off. In this calculation, we have included all relevant energy losses and production processes. It is shown that the protons produced from the target nuclei through recoil and evaporation processes dominate the spectrum below 350 MeV. These calculations have been carried out over an energy region from 20 MeV to 40 GeV and up to a depth of 40 g/cm² of the atmosphere over a latitude with zero geomagnetic cut-off for both the periods of minimum and maximum solar modulation.