Wave Trace Research Articles

A free boundary problem for the wave equation

In this paper we discuss the motion of a frictionless piston contained in a tube which is filled with a hydraulic fluid.The fluid is assumed to be inviscid but com pressible. The mathematical problem is that of solving the wave equation in a domain with an a priori unknown boundary (the piston trajectory).The methods for solving the problem amount essentially to a wave tracing technique. The report is concluded with some numerical results and a comparison of these results with an entirely linear analysis of the same problem.

Digital Blood Flow Rates in Psoriasis under Normal Conditions and in Response to Local Mild Ischemia

It has been reported that a dysfunction of the blood vessels exists at some distance from visible lesions in patients with psoriasis (1). In the study cited, a vascular dysfunction was said to be present in the digit. This conclusion was derived from analyses of the contour of digital pulse wave tracings obtained with a photoelectric ple-thysmograph described by Hertzman (2). The digital plethysmograms of patients with psoriasis are said to have an anacrotic limb whose slope rises more slowly than normal, with a resultant increased crest time, and a poorly defined or absent dicrotic notch in the catacrotic limb. If a dysfunction of the peripheral circulation exists, it might be manifest as altered minute-volume blood flow. Accordingly, the present study was designed to compare quantitatively the blood flow rates and pulse wave contours in the digits of patients with psoriasis and groups of healthy individuals under resting conditions and after induced, local mild ischemia. The latter procedure was included as a part of the experiments, since it is generally recognized that the resting digital blood flow rates may vary considerably (3) and that the augmented minute-volume flow which follows local mild ischemia is a more reliable index of the status of the blood vessels (4).

Abnormal brain wave patterns in Kwashiorkor

1. 1. Electroencephalographic tracings were done on 25 children with kwashiorkor. Coincident with the symptoms (enamel paint dermatosis, depigmentation, edema, mental apathy or constant misery) the brain wave tracings were as a rule abnormal with activity below the usual range of frequency considering each age group (8 months to 5 years). Two children, who showed normal mental response and were able to sit up on admission, had normal EEG records. 2. 2. In 7 patients who did not survive, the EEG was taken before a comatose state developed. It showed a preponderance of 1–3 c/sec. slow waves, but absence of a dominant basic occipital frequency in most cases. The range varied between 1–6 c/sec. 3. 3. Most children recovered following administration of a high protein diet and vitamins. On admission, their brain wave pattern was not significantly different from that of the fatalities. Upon recovery, when the edema and the skin lesions had disappeared and the children were able to sit up, the EEG was found to be within normal limits in spite of persisting anemia. 4. 4. In 2 cases of kwashiorkor and vitamin deficiency repeated follow-up studies to show complete normalization. The possibility of a permanent brain damage due to malnutrition must be considered.

Arterenol (norepinephrine) and vascular headache of the migraine type; studies on headache.

It has been appreciated for some time that agents that effectively induce cranial vasoconstriction also reduce the intensity of, or eliminate, vascular headache of the migraine type. The potency of arterenol (norepinephrine) as a vasoconstrictor suggested that it might affect the intensity and duration of the pain and further elucidate the mechanism of vascular headache.* METHOD Arterenol in a dilution of 4 cc. of a 0.2% solution in a liter of 5% dextrose in water was administered intravenously at an average rate of 1 drop per second, or sufficient to raise the systolic blood pressure 10 to 40 mm. Hg. With the patient supine, blood pressure and pulse were determined at intervals of 1 to 2 minutes initially and thereafter every 10 to 15 minutes. Pulse wave tracings of the involved cranial arteries were made using the apparatus described in a previous communication. 4 Deep-pain thresholds of the scalp were

Influence of Athletic Training on the Resting Cardiovascular System

Abstract Cardiovascular changes in 18 college athletes during training, compared with 15 controls, can be interpreted as the result of the interplay of basic factors (peripheral resisttance, aortic volume-elasticity, stroke volume and heart rate). The observed effects of athletic training seem to be due to increased elasticity and resting stroke volume associated with a compensating decrease in heart rate. Brachial pulse wave tracings (systolic amplitude) differentiate the athletes from the controls, but do not change by a statistically acceptable amount during training. Changes in the resting heart rate constitute a useful test of the cardiovascular aspect of athletic conditioning, the validity being r = 0.76.

THE GENETICS OF EPILEPSY

Study of the incidence of epilepsy among 12,119 of the near relatives of 2130 epileptics and among 55 twin pairs affected by seizures, together with analysis of the brain wave records of 470 relatives and of the 55 twins, leads to the conclusion that epilepsy per se is not inherited but a tendency or predisposition usually is inherited. The terms, genetic and acquired epilepsy, should replace the meaningless conventional terms essential and symptomatic. Probably in most patients both genetic and acquired factors are present. The incidence of epilepsy is higher among the near relatives of epileptics if pathology of the brain did not antedate the onset of seizures, if the patient's epilepsy began early in life, if he was mentally abnormal at birth, if he has petit mal and if the patient is female. The electroencephalogram is an hereditary trait and brain wave tracings, properly made and interpreted, may be of positive value in visualizing a transmitted quality which (with the possible help of acquired patho...

Apparatus for recording the rate of cooling of a kata-thermometer

During the course of an investigation it was necessary to record the change in the rate of cooling of a kata-thermometer, when a cloth was applied to its bulb, at an instant when the alcohol stood at a certain level in the stem of the kata. An apparatus is described by which the cloth is applied, the time noted, and recording started, all at the same instant. A record of the rate of cooling is made in the form of a simple harmonic wave trace, a drum being made to oscillate in accordance with the movements of a suitable pendulum, while the pen moves axially on the drum at the rate of fall of the liquid in the thermometer.