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PREFERENTIAL INHIBITION OF THE GROWTH OF VIRUS-TRANSFORMED CELLS IN CULTURE BY RIFAZONE-82, A NEW RIFAMYCIN DERIVATIVE

Description: Rifazone-8{sub 2} (R-8{sub 2}), a new rifamycin derivative, is shown to preferentially inhibit the growth of virus-transformed chick cells in culture. Macromolecular synthesis and glucose uptake of transformed cells are also appreciably decreased in the presence of low concentrations of R-8{sub 2} where the normal cells appear unaffected. While R-8{sub 2} is shown to be a selective inhibitor of RNA-directed DNA polymerase in vitro, its action on the growth of transformed cells may involve some other mechanism.
Date: March 28, 1974
Creator: Bissell, Mina J.; Hatie, Carroll; Tischler, Allan N. & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

STOCHASTICITY

Description: Detailed examination of computed particle trajectories has revealed a complexity and disorder that is of increasing interest to accelerator specialists. To introduce this topic, the author would like you to consider for a moment the analysis of synchrotron oscillations for a particle in a coasting beam, regarded as a problem in one degree of freedom. A simple analysis replaces the electric field of the RF-v cavity system by a traveling wave, having the speed of a synchronous reference particle, and leads to a pair of differential equations of the form dy/dn = -K sin {pi}x, (1A) where y measures the fractional departure of energy from the reference value {pi}x measures the electrical phase angle at which the particle traverses the cavity, and K is proportional to the cavity voltage; and dx/dn = {lambda}{prime}y, (1b) in which {lambda}{prime} is proportional to the change of revolution period with respect to particle energy. It will be recognized that these equations can be derived from a Hamiltonian function H = (1/2){lambda}{prime}y{sup 2}-(K/{pi})cos {pi}x. (2) Because this Hamiltonian function does not contain the independent variable explicitly, it will constitute a constant of the motion and possible trajectories in the x,y phase space will be just the curves defined by H = Constant, namely the familiar simple curves in phase space that are characteristic of a physical (non-linear) pendulum.
Date: May 1, 1974
Creator: Laslett, L. Jackson.
Partner: UNT Libraries Government Documents Department

$mu$$sup +$SR spectroscopy: the positive muon as a magnetic probe in solids

Description: Through its asymmetric decay, the positive muon acts as a sensitive detector of the interactions of its spin with the medium in which it comes to rest. Development of the $mu$$sup +$SR spectroscopy technique is described, and recent applications of the $mu$$sup +$ as a probe are discussed. Results for hyperfine fields in ferromagnets and impurity states in nonmetals are presented with suggestions for future studies. 6 figures. (auth)
Date: June 1, 1974
Creator: Brewer, J.H.; Fleming, D.G.; Crowe, K.M.; Johnson, R.F.; Patterson, B.D.; Portis, A.M. et al.
Partner: UNT Libraries Government Documents Department

Evaluation of the ERC virtual impactor

Description: Measurements have been made on a dichotomous virtual impactor developed by the Environmental Research Corporation. The object was to study the feasibility of employing the virtual impaction scheme in air samplers to collect size fractionated particle samples for subsequent x-ray fluorescence analysis. The size separation characteristics and losses as a function of particle size at specific locations within the apparatus were determined. It was found that except for the intrinsic losses near the size cut point, most of the losses can be significantiy reduced with improved design. The prospect of large scale deployment of virtual impactors for continuous air monitoring is favorable. (auth)
Date: January 1, 1974
Creator: Loo, B.W. & Jaklevic, J.M.
Partner: UNT Libraries Government Documents Department

Infrared spectrum of curium-244

Description: The spectrum of curium-244 has been observed on the high resolution Fourier-transform spectrometer at Laboratoire Aime Cotton. An electrodeless lamp containing 50 $mu$g of CmI$sub 3$ was run for 12 hours and 800,000 points were taken. A total of 1743 lines have been ascribed to curium and 87 percent of the lines have been assigned to transitions between known energy levels.
Date: September 1, 1974
Creator: Conway, J.G.; Blaise, J. & Verges, J.
Partner: UNT Libraries Government Documents Department

LIQUID XENON MULTIWIRE PROPORTIONAL CHAMBERS FOR NUCLEAR MEDICINEAPPLICATIONS

Description: The need for improved spatial resolution in nuclear medicine has long been recognized. Notable attempts to achieve this goal are the gas-filled wire chambers and solid-state detectors. (1) However, at energies above 100 keV, gas-filled chambers suffer from poor detection efficiency and a long recoil electron range in the gas. While it is advantageous to pressurize these chambers to 10 or more atmospheres, structural design of the thin window presents a formidable task. High-resolution optimal collimators do not appear to have sufficient strength to be used as a pressure support window. Solid-state detectors, while having the potential of a gamma camera with a superb energy resolution, are presently studied on a very small scale due to technological and cost limitations. Aside from the detector, the parallel-hole collimator presents a real limit to the resolution of the camera. A factor of two improvement in the resolution results in a factor of four loss in the collimator's transmission. A careful analysis of optimal collimators and the application of collimators designed for a specific depth range and resoluation are part of our overall program. Our goal has been the development of a liquid-xenon multiwire gamma camera with 2- to 3-mm spatial resolution, high counting-rate performance, high sensitivity, and the potential for scaling-up in size. Important ingredients for successful imaging in the prototype chamber discussed in this paper were the discovery of electron multiplication in liquid xenon, (2) the development of reliable purification techniques, (3) and the ability to extract electrons from the liquid into the gaseous phase. This paper is specifically addressed to the subject of detector development with liquid-xenon totally-filled chambers and recent work with dual-phase chambers in which the {gamma} rays are converted in the liquid phase and are electronically detected in the gaseous phase.
Date: May 1, 1974
Creator: Zaklad, H.; Derenzo, S.E.; Budinger, T.F. & Alvarez, L.W.
Partner: UNT Libraries Government Documents Department

TEST OF A LIQUID ARGON CHAMBER WITH 20-u m RMS RESOLUTION

Description: A measurement of the spatial resolution of a liquid-argon filled chamber was performed with minimum ionizing particles. Two multi-strip chambers with 20-{micro}m strip spacing operating in the ionization mode were used in the experiment. They perform in accordance with a simple model based on electron diffusion. An estimate of the amount of electron diffusion in liquid argon is given and the time jitter distribution has a FWHM of 200 ns. Under best conditions, the spatial resolution is better than 20 {micro}m rms with an efficiency of nearly 100%.
Date: July 1, 1974
Creator: Derenzo, S.E.; Kirschbaum, A.R.; Eberhard, P.H.; Ross, R.R. & Sclmitz,F.T.
Partner: UNT Libraries Government Documents Department