Use of ultrasound for noninvasive study of blood vessel responsiveness

To provide a noninvasive means for studying individual macroscopic blood vessels, an ultrasound scanner was modified to provide a recording of blood vessel diameter. The instrument has A- and B-modes of signal display. The B-mode is used to position the probe and the A-mode to measure vessel diameter. The A-mode has two electronic gates for tracking the echo from each of two structures, i.e., near and far wall of vessel. The front gate was modified to pick up the falling rather than rising edge of a peak generated by the vessel wall. An analog signal proportional to the distance between gates was derived for recording with a strip-chart recorder. Probe holders were constructed to optimize positioning and holding of probe. Stability was excellent (reading varied 0.05 mm over 1 h). Axial resolution was between 0.3 and 0.73 mm. Discrepancy of measurements of plastic tubing made by ocular and ultrasound varied from 1.1 to 4.6%. Discrepancy with lightly fixed vessels was 2.7-8.2%. Ex vivo measurements on vessels with viable smooth muscle were more variable, perhaps because of actual change during measurements. Changes in vessel diameter induced by change in hydrostatic pressure and exposure to histamine were recorded.

Acquisition and Analysis of Powder X-Ray Diffraction Data Using CALS Chromatographic Software

A conventional semi-automated powder X-ray diffractometer that was previously equipped with a strip chart recorder for data acquisition has been interfaced to an HP 1000 minicomputer via an analog-to-digital converter. Data acquisition and analysis is now accomplished using CALS chromatographic software and two in-house-developed FORTRAN 77 computer programs. This has resulted in significant improvements in experimental repeatability and accuracy, decreased sample turn-around times, and rapid and facile analysis, manipulation, and comparison of crystallographic data.

Nondestructive, Continuous Rapid Measurement and Control of Flock Density

A nondestructive technique for rapidly and continuously measuring the density of flocked fabric was developed and used to continuously monitor an experimental flocking range. A sensing device measured the capacitance of a capacitor when the fabric with adhesive passed through it. This value was saved and compared with the value read when the flocked substrate passed through a second transducer downstream. A process monitoring computer received these signals and output a signal to a strip chart recorder proportional to the mass of flock on the substrate. The recorded signal could then be used to control the uniformity of flock deposition on the substrate.

Tiltmeter observations at Cape Yakataga, Alaska, preceding the St. Elias earthquake, M = 7.8, of February 28, 1979

abstract On February 28, 1979 at 2127 UTC, a magnitude of 7.7 earthquake occurred near Mt. St. Elias in southeastern Alaska. The U.S. Geological Survey has been operating a shallow borehole tiltmeter at Cape Yakataga, Alaska, 80 km southeast of the epicenter since March 1977. This instrument has been telemetering data to Menlo Park, California, via Landsat satellite with an onsite strip chart recorder as backup. The strip chart record shows fluctuations due to meteorological effects. However, for 2 months preceding the earthquake, the east-west trace is steady at the 2-μrad level. Instrumental response at the time of the earthquake shows an offset of 4.5 μrad with an exponential decay over several hours to a new level. Five days after the earthquake, both north-south and east-west components returned to pre-earthquake levels. This postseismic tilting may be complicated by meteorological effects.