Effects of calcium-free perfusion on excitation-contraction coupling in heart and skeletal muscle.

Interventricular septa and semimembranosus accessorius muscles (SMA) from the guinea pig and frog gastrocnemius (FG) muscles were vascularly perfused and isolated for mechanical and radioisotope flux measurements. Since calcium deprivation causes progressive electrical inexcitability, 100 muM La was included in all calcium-free solutions (0-Ca, 100-La) to stabilize the membrane. Perfusion of ventricular septa with such solutions resulted in tension (P) and dP/dt declines with half-times (t 1/2) = 11 sec, similar to the most rapid phase of 45Ca efflux.

Evaluation of fiber optical waveguides using brillouin spectroscopy.

Optical scattering loss in fiber optical waveguides is the sum of the bulk material scattering and excess scattering loss due to imperfections in the waveguide structure. The recently developed Brillouin spectroscopic technique for evaluating bulk scattering has been extended to fiber waveguides, and a detailed investigation has been performed on a borosilicate clad-pure fused silica core waveguide. The technique has been found to be useful in evaluating scattering due to waveguide imperfections that have been determined to occur at the core-cladding interface.

Development of a calorimetric method for making precision optical absorption measurements.

Present trends toward the development and application of exceptionally high quality optical materials have made requirements on optical loss so stringent that they exceed the capabilities of existing measurement techniques. This work describes a calorimetric method for determining optical absorption in bulk materials which is over an order of magnitude more sensitive than previous methods. The large circulating optical power within a laser cavity is used to heat a small rod shaped sample of test materialplaced within the cavity.