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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12

All sources NASA NTRS DOE OSTI

NASA NTRS1976

Implantable electrode for recording nerve signals in awake animals

An implantable electrode assembly consisting of collagen and metallic electrodes was constructed to measure simultaneously neural signals from the intact nerve and bioelectrical noises in awake animals. Mechanical artifacts, due to bodily movement, were negligibly small. The impedance of the collagen electrodes, measured in awake cats 6-7 days after implantation surgery, ranged from 39.8-11.5 k ohms at a frequency range of 20-5 kHz. Aortic nerve activity and renal nerve activity, measured in awake conditions using the collagen electrode, showed grouped activity synchronous with the cardiac cycle. Results indicate that most of the renal nerve activity was from postganglionic sympathetic fibers and was inhibited by the baroceptor reflex in the same cardiac cycle.

Ninomiya, I.↗

NASA NTRS1975

Tutorial: angiocardiography, past and present

The contribution of X-ray methodology and angiocardiography in the ability to study cardiac and cardiovascular function is presented. Angiocardiography remains the most reliable method for determination of overall chamber size and shape particularly in the face of disease states of varying etiologies. It also presents the most accurate means for obtaining dimensional information concerning the heart and blood vessels without the use of surgery or attachment of transducers.

Sandler, H.↗

NASA NTRS1979

High-Speed, high-power, switching transistor

Silicon transistor rate for 200 angstroms at 400 to 600 volts combines switching speed of transistors with ruggedness, power capacity of thyristor. Transistor introduces unique combination of increased power-handling capability, unusally low saturation and switching losses, and submicrosecond switching speeds. Potential applications include high power switching regulators, linear amplifiers, chopper controls for high frequency electrical vehicle drives, VLF transmitters, RF induction heaters, kitchen cooking ranges, and electronic scalpels for medical surgery.

Carnahan, D.↗

NASA NTRS1977

Effect of suprachiasmatic lesions on diurnal heart rate rhythm in the rat

Heart rate and locomotor activity of rats kept under 12L/12D illumination regimen were recorded every six minutes for ten days using implantable radio transmitters. Some of the rats then received bilateral RF lesions into the suprachiasmatic nucleus (SCN). Control sham operations were performed on the rest of the animals. After recovery from surgery, recording of heart rate and locomotor activity was continued for ten days. SCN-lesioned rats showed no significant diurnal fluctuation in heart rate, while normal and sham-operated rats showed the normal diurnal rhythm in that function. The arrhythmic diurnal heart-rate pattern of SCN rats appeared to be correlated with their sporadic activity pattern. The integrity of the suprachiasmatic nucleus is therefore necessary for the generation and/or expression of diurnal rhythmicity in heart rate in the rat.

Saleh, M. A.↗

NASA NTRS1978

Purification and cultivation of human pituitary growth hormone secreting cells

The maintainance of actively secreting human pituitary growth hormone cells (somatotrophs) in vitro was studied. The primary approach was the testing of agents which may be expected to increase the release of the human growth hormone (hGH). A procedure for tissue procurement is described along with the methodologies used to dissociate human pituitary tissue (obtained either at autopsy or surgery) into single cell suspensions. The validity of the Biogel cell column perfusion system for studying the dynamics of GH release was developed and documented using a rat pituitary cell system.

Hymer, W. C.↗

NASA NTRS1979

Intra-ocular pressure normalization technique and equipment

A method and apparatus is described for safely reducing abnormally high intraocular pressure in an eye during a predetermined time interval. This allows maintenance of normal intraocular pressure during glaucoma surgery. A pressure regulator of the spring-biassed diaphragm type is provided with additional bias by a column of liquid. The hypodermic needle can be safely inserted into the anterior chamber of the eye. Liquid is then bled out of the column to reduce the bias on the diaphragm of the pressure regulator and, consequently, the output pressure of the regulator. This lowering pressure of the regulator also occurs in the eye by means of a small second bleed path provided between the pressure regulator and the hypodermic needle.

Baehr, E. F.↗

NASA NTRS1980

Intra-ocular pressure normalization technique and equipment

A method and apparatus for safely reducing abnormally high intraocular pressure in an eye during a predetermined time interval is presented. This allows maintenance of normal intraocular pressure during glaucoma surgery. According to the invention, a pressure regulator of the spring biased diaphragm type is provided with additional bias by a column of liquid. The height of the column of liquid is selected such that the pressure at a hypodermic needle connected to the output of the pressure regulator is equal to the measured pressure of the eye. The hypodermic needle can then be safely inserted into the anterior chamber of the eye. Liquid is then bled out of the column to reduce the bias on the diaphragm of the pressure regulator and, consequently, the output pressure of the regulator. This lowering pressure of the regulator also occurs in the eye by means of a small second bleed path provided between the pressure regulator and the hypodermic needle. Alternately, a second hypodermic needle may be inserted into the eye to provide a controlled leak off path for excessive pressure and clouded fluid from the anterior chamber.

Mcgannon, W. J.↗

NASA NTRS1980

Neuron analysis of visual perception

The receptive fields of single cells in the visual system of cat and squirrel monkey were studied investigating the vestibular input affecting the cells, and the cell's responses during visual discrimination learning process. The receptive field characteristics of the rabbit visual system, its normal development, its abnormal development following visual deprivation, and on the structural and functional re-organization of the visual system following neo-natal and prenatal surgery were also studied. The results of each individual part of each investigation are detailed.

Chow, K. L.↗

NASA NTRS1980

Questions of diagnosing and treating Meniere's disease

The possibilities of diagnosis and treatment of Meniere's disease are considered. Attention is given to the use of dehydration tests which are based on glycerol administration or intravenous injection of furosemide. The risks of bilateral sensorineural hearing impairment in prolonged conservative treatment is emphasized. The data of auditory function study before and following endolymphatic sac surgery are presented.

Khechinashvili, S. N.↗

NASA NTRS1983

Late skin damage in rabbits and monkeys after exposure to particulate radiations

Preliminary results are reported of experiments on the late effects of exposure to particulate radiations on stem cell populations. Skin biopsies were taken from the ears of rabbits irradiated 2-5 years previously with 530 MeV/amu Ar ions (LET 90 keV/micron), or 365 MeV/amu Ne ions (LET 35 keV micron), and from the chests and inner thighs of rhesus monkeys irradiated 16-18 years previously with 32-MeV protons (LET about 1.2 keV/micron). Skin fibroblast cultures obtained from the biopsy samples in rabbits were observed to undergo dose-dependent decreases in in vitro life span, with estimated survival curves showing the effects of Ar-ion irradiation to be more severe than those of Ne-ion irradiation. In addition, the healing of the biopsy wound was observed to become slower as radiation dose increased. In the monkey, radiation reduced the average number of fibroblasts at the time of cessation of growth in culture. Results thus demonstrate the capacity of skin sampling to reveal stem cell destruction, and have important implications for astronauts and other persons at risk of particle exposure with regard to healing responses to trauma or surgery.

Bergtold, D. S.↗

NASA NTRS1984

No effect of sex steroids on compensatory muscle hypertrophy

The effects of orchiectomy and/or subcutaneously implanted testosterone propionate (TP) on the hypertrophic response of rat plantaris muscles to functional overload (induced by bilateral removal of gastrocnemius and soleus muscles) are investigated experimentally. Muscle wet weight, metabolic substrate oxidation, and cytosolic androgen-receptor binding are measured, and the results are presented in tables. Eight weeks after surgery, the plantaris muscle weight as a percentage of body weight is found to be about twice that in rats without muscle overload, regardless of the sex-hormone status. Overloading causes decreased ability to oxidize glucose and pyruvate, decreased succinate dehydrogenase specific activity, and no change in the ability to oxidize beta-hydroxybutyrate or in androgen-receptor binding. The oxidative response is unaffected by orchiectomy or TP or both. It is argued that the actions of sex hormones and functional overload are not synergistic.

Max, S. R.↗

NASA NTRS1983

Radial maze performance in three strains of mice - Role of the fimbria/fornix

Three strains of mice were tested on an 8-arm radial maze, an index of hippocampus-dependent spatial memory. Levels of performance differed betweens strains with C57Br/cdj greater than Balb/cj greater than C57B1/6j. Lesions of the fimbria/fornix disrupted performance in the C57Br and Balb strains: the C57Bl mice never performed better than chance before or after surgery. Choline acetyltransferase activity in hippocampus was not correlated with radial maze performance. These findings suggest a possible genetic contribution towards radial maze behavior.

Reinstein, D. K.↗

NASA NTRS1988

Real-Time Keratometer

Optical/electronic keratometer system produces contour map of corneal surface illuminated by infrared light pulses. Prevents operator error and eliminates need to apply fluorescent liquids to cornea. Keratometer provides both video display and numerical recording for corneal-transplant and radial-keratotomy surgery and for contact-lens fitting. Optical system of keratometer, circular grating pattern transmitted to corneal surface reflected onto identical circular grating on surface of fiber plate, producing Moire pattern. Data-analysis-and-display mode, laser light pulsed, and Moire pattern converted to digital information in frame grabber. Digital picture information sent to computer for processing and display.

Frazer, Robert E.↗

NASA NTRS1988

Clinical applications of computerized thermography

Computerized or digital, thermography is a rapidly growing diagnostic imaging modality. It has superseded contact thermography and analog imaging thermography which do not allow effective quantization. Medical applications of digital thermography can be classified in two groups: static and dynamic imaging. They can also be classified into macro thermography (resolution greater than 1 mm) and micro thermography (resolution less than 100 microns). Both modalities allow a thermal resolution of 0.1 C. The diagnostic power of images produced by any of these modalities can be augmented by the use of digital image enhancement and image recognition procedures. Computerized thermography has been applied in neurology, cardiovascular and plastic surgery, rehabilitation and sports medicine, psychiatry, dermatology and ophthalmology. Examples of these applications are shown and their scope and limitations are discussed.

Anbar, Michael↗

NASA NTRS1988

On the origin of steep edges and filaments in vorticity and potential vorticity fields

High-resolution numerical calculations are shown which capture the fundamental process responsible for the intensification of vorticity gradients in an isolated vortex subject to externally imposed distrubances. Imposition of almost any weak strain or shear field in stripping away the relatively weak vorticity at the edge of the vortex and leaves it with gradients four to six orders of magnitude greater than in the initial state. Calculations displaying such enormous gradients have never been reported previously, because of the artificial eddy diffusivities that always limit such gradients in standard numerical models. The present calculations, which have no such limitations, have been made possible by the development of a novel and robust new numerical technique for vortex dynamics called contour surgery.

Dritschel, D. G.↗

NASA NTRS1991

Computer-Driven Keratometer

Simple optical system measures corneal deformations. Shuttered laser briefly illuminates subject's eye through reticle, projecting concentric rings of light on eye. Reflected by beam splitter and mirror into solid-state video camera, ring pattern compared with reference pattern by computer. Keratometer assists in rapid diagnosis of eye ailments and preparation of cornea for surgery. Unit does not require critical alignment with eye; results more reliable, and easier to use.

Baroth, Edmund C.↗

NASA NTRS1991

Cognitive consequences of clumsy automation on high workload, high consequence human performance

The growth of computational power has fueled attempts to automate more of the human role in complex problem solving domains, especially those where system faults have high consequences and where periods of high workload may saturate the performance capacity of human operators. Examples of these domains include flightdecks, space stations, air traffic control, nuclear power operation, ground satellite control rooms, and surgical operating rooms. Automation efforts may have unanticipated effects on human performance, particularly if they increase the workload at peak workload times or change the practitioners' strategies for coping with workload. Smooth and effective changes in automation requires detailed understanding of the congnitive tasks confronting the user: it has been called user centered automation. The introduction of a new computerized technology in a group of hospital operating rooms used for heart surgery was observed. The study revealed how automation, especially 'clumsy automation', effects practitioner work patterns and suggest that clumsy automation constrains users in specific and significant ways. Users tailor both the new system and their tasks in order to accommodate the needs of process and production. The study of this tailoring may prove a powerful tool for exposing previously hidden patterns of user data processing, integration, and decision making which may, in turn, be useful in the design of more effective human-machine systems.

Cook, Richard I.↗

NASA NTRS1989

Excimer laser interaction with dentin of the human tooth

The use an excimer laser produced many unusual conical structures within the dentin of the inner part of the human tooth. By varying the frequency of the laser one can disperse the energy and cause more bleeding in laser surgery, but not destroy the cells associated with the incision. Therefore, the healing process will virtually be without scarring. Whereas, using the infrared laser the blood loss would be less, but the healing process would tend to be longer because cells are being destroyed due to the cauterization effect of the laser. The question is, are these structures produced as an interaction with the laser or are they an intrinsic part of the structure. The effects of the laser interaction upon dentin was studied, and in using electron microscopy the interaction of the excimer laser upon the tooth dentin and other various biological tissue is more clearly understood.

Hammond, Ernest C., Jr.↗