Charles T. Walker

Hemodynamic Studies in Chronic Uremia

Hemodynamic functions and blood volume were observed in patients with chronic uremia. Thirty-one patients had clinical features of circulatory congestion and 37 did not. The degree of anemia and acidosis was comparable in both groups. However, creatinine clearance was significantly lower in patients with circulatory congestion. Both groups of patients had greater blood pressure, heart rate, plasma volume, and total peripheral resistance than normal. Resting cardiac output was abnormally decreased in 19% of the patients with circulatory congestion and in 14% of patients without features of circulatory congestion. There was no correlation between blood volume and blood pressure. Intravenous digitalization of seven of the patients with circulatory congestion produced clinical and hemodynamic improvement in only two. Hemodialysis effected an increase in cardiac output and a decrease in total peripheral resistance in six patients with congestion. In seven patients without circulatory congestion after dialysis there was a fall in plasma and blood volume, associated with a slight decrease in cardiac output. It is suggested that congestion of the circulation in chronic uremia results from a variety of hemodynamic, myocardial, and metabolic alterations, rather than from any single abnormality.

Raman scattering by localized modes

Abstract Raman scattering from the T2 fundamental and T2 and A1 second harmonics of the localized mode for H- and D- in CaF2, SrF2 and BaF2 are reported, and are in substantial agreement with theoretical explanations of the i.r. spectra for the same systems.

Impurity induced vibrational spectra in BaF2:H-☆

Abstract An experimental study of the impurity induced Raman scattering and infrared absorption spectra in BaF2:H- is reported. The H- local mode sidebands are observed by Raman scattering for the first time, and are seen to agree with those observed by infrared absorption. In contrast to earlier work a T2 symmetry phonon resonance is observed in the infrared sidebands at 285 cm-1 and is also observed directly in first-order Raman scattering, although with a different temperature dependence for the half-width. Lastly, an impurity-induced band of predominantly A1 symmetry is also seen directly in first-order Raman scattering, and lies in the acoustic phonon region of the host BaF2.

Method for Determining Elastic Constant Changes

A method for determining the change in elastic constants as a function of some parameter such as temperature or pressure is described. The method is a modification of the pulsed radio frequency sound technique, in which the echoes are mixed with a signal from a free‐ringing quartz crystal in order to extract small phase changes in the echoes. Conventional ultrasonic attenuation equipment, which ordinarily is too imprecise for such work, is utilized. The precision is shown to be about 2 parts in 105.

Comparison of Phonon-Active and Infrared-Active Lattice Resonances for U Centers in Alkali Halides

We have previously published low temperature thermal conductivity data for KI doped with H- and D- ions.(1) In addition we have also discussed (1, 2) but not published, our data for H- and D-ions in KCl, KBr, and RbCl. Of these systems only the KI data exhibited a resonant phonon interaction. The data for KI with H-and D- ions exhibited a resonant dip on the high temperature side of the conductivity maximum at a temperature of about l8°K. Moreover, the position or shape of the dip did not depend on the dopant used, and the resonance is therefore mass independent. In this paper we will confine our attention chiefly to KI. A detailed account of all our thermal conductivity data and analysis by means of Green’s functions will be published separately in a more lengthy paper.