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Results for “Radiotelemetry”

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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14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Tracking Avian Reservoirs of Arboviruses using Remote Sensing and Radiotelemetry

Encephalitis is caused by a virus that is transmitted by mosquitoes between mammalian hosts. The virus is closely related to the West Nile virus (WNV), which started in New York in 1999, and has since spread to 25 states. Like encephalitis, WNV is vectored by mosquitoes, and the primary hosts are birds; humans are accidental, or'dead-end' hosts. Very little is understood about the behavior of these bird populations, and how they intersect - both in time and in space - with mosquito populations. Exploring these relationships is the first step in developing models for encephalitis and WNV transmission risk. This project combines remotely sensed data with radiotelemetry to create a spatiotemporal map of encephalitis viral activity in bird and mosquito populations in the Sacramento Valley of California. Specifically, remote sensing (RS) and geographic information system (GIS) technologies were used to characterize habitats utilized by both avian viral reservoirs and the mosquitoes that vector encephalitis. Radiotelemetry and serosurveys (blood) were then used to spatially and temporally track the patterns of infection. The project uses Landsat ETM+ multitemporal satellite data to characterize habitats utilized by both birds and the mosquito vectors. Mist nets were used to sample members of individual flocks of blackbirds and cowbirds over a period of several months; these birds were then bled to assess their viral status, banded, and fitted with transmitters. Radiotelemetry was used to spatially and temporally track the distribution of banded birds and their associated flocks. The movement of these indicator flocks were compared with the location of remotely sensed (adult and larval) mosquito habitats to determine the intersection of bird's and vectors; this is key in understanding where and when transmission occurs from bird to bird, as well as from bird to mammal, via mosquito. The relationships found during the project are being used to generate a model of encephalitis transmission risk in California.

Beck, L.↗
NASA NTRS1997

Radiotelemetry

Radiotelemetry, by definition, is the science and technology of automatic measurement and transmission of data by radio from remote sources, as from space vehicles, to receiving stations for recording and analyis. It involves the preparatio of data generated at remote sources, the transmission of data through radio channels, and the processing of data at the recieving stations. Behind these three tasks, how to convey the information in a reliable and timely manner through a communication link is the most fundamental problem to be addressed in this field.

Radiotelemetry↗
NASA NTRS1971

EEG electrode-amplifier harness

Astronaut electrode-amplifier helmet harness for cable and radiotelemetry acquisition of EEG, EGO, EMG and blood pressure data on noninterference basis

Adey, W. R.↗
NASA NTRS1972

Use of the Doppler technique to track free roaming animals from satellites

The application of the Doppler effect to track wild animals is discussed, with artificial satellites used to provide wide range coverage. The limitations of radiotelemetry for the purpose of tracking animals are presented. The advantages of the artificial satellite, with specific reference to the Nimbus satellite, are examined.

Maxwell, J. C.↗
NASA NTRS1972

Biomedical technology transfer applications of NASA science and technology

The identification and solution of research and clinical problems in cardiovascular medicine which were investigated by means of biomedical data transfer are reported. The following are sample areas that were focused upon by the Stanford University Biomedical Technology Transfer Team: electrodes for hemiplegia research; vectorcardiogram computer analysis; respiration and phonation electrodes; radiotelemetry of intracranial pressure; and audiotransformation of the electrocardiographic signal. It is concluded that this biomedical technology transfer is significantly aiding present research in cardiovascular medicine.

Source record↗
NASA NTRS1977

The chimpanzee as a flight candidate

Some of the characteristics that make the chimpanzee an attractive animal model (anatomy, size, intelligence, and durability) also create some very unique problems. The universally recognized problems of availability and expensive maintenance, combined with the often underestimated problems associated with routine housing, husbandry, restraint, and medical management, severely limit the availabe avenues of approach. Problems involved in using implantable, multichannel radiotelemetry systems to monitor cardiodynamics in chimpanzees are discussed.

Source record↗
NASA NTRS1978

Effects of exercise and excitement on mesenteric and renal dynamics in conscious, unrestrained baboons

Radiotelemetry was used to measure arterial pressure and mesenteric and renal blood flows from nine unrestrained, conscious baboons during periods of rest, moderate exercise, and extreme excitement. A description of the experiments hardware is presented, including artificial depressants phenylcyclidine hydrochloride, 0.5-1.0 mg/kg, and pentobarbital sodium, 15 mg/kg, and an ultrasonic telemetry flow meter. Results showed rising heart rate and arterial pressure coupled with a reduction of mesenteric and renal flows as the level of exercise was increased. These findings are compared with mesenteric and renal flows somewhat above control level, but relatively stable heart rate and arterial pressure, postprandially. Attention is given to a quantitative analysis of the experimental results.

Vatner, S. F.↗
NASA NTRS1982

Low-Noise Implantable Electrode

New implantable electrocardiogram electrode much less sensitive than previous designs to spurious biological potentials. Designed in novel "pocket" configuration, new electrode is intended as sensor for radiotelemetry of biological parameters in experiments on unrestrained subjects. Electrode is esentially squashed cylinder that admits body fluid into interior. Cylinder and electrical lead are made of stainless steel. Spot welding and crimping are used for assembly, rather than soldering.

Lund, G. F.↗
NASA NTRS1987

Gravitational haemodynamics and oedema prevention in the giraffe

The question of how giraffes avoid pooling of blood and tissue fluid (edema) in dependent tissues of their extremities is addressed. As monitored by radiotelemetry, the blood and tissue fluid pressures that govern transcapillary exchange vary greatly with exercise. These pressures, combined with a tight skin layer, move fluid upward against gravity. The skin thus functions like a natural antigravity suit. Other mechanisms that prevent edema include precapillary vasoconstriction and low permeability of capillaries to plasma proteins.

Hargens, Alan R.↗
NASA NTRS1992

Effects Of Asymmetry Of NRZ Data Signals On Performance

Report presents theoretical analysis of effects of asymmetry in binary non-return-to-zero (NRZ) data signals upon performance of radiotelemetry system. Simple mathematical model predicting overall degradation of bit signal-to-noise ratio of telemetry system derived. Shows degradation increases with asymmetry.

Nguyen, Tien M.↗
NASA NTRS1997

The Gravity of Giraffe Physiology

By virtue of its tallness and terrestrial environment, the giraffe is a uniquely sensitive African animal to investigate tissue adaptations to gravitational stress. One decade ago, we studied transcapillary fluid balance and local tissue adaptations to high cardiovascular and musculoskeletal loads in adult and fetal giraffes. Previous studies by Goetz, Pattersson, Van Citters, Warren and their colleagues revealed that arterial pressure near the giraffe heart is about twice that in humans, to provide more normal blood pressure and perfusion to the brain. Another important question is how giraffes avoid pooling of blood and tissue fluid (edema) in dependent tissue of the extremities. As monitored by radiotelemetry, the blood and tissue fluid pressures that govern transcapillary exchange vary greatly with exercise. These pressures, combined with a tight skin layer, move fluid upward against gravity. Other mechanisms that prevent edema include precapillary vasoconstriction and low permeability of capillaries to plasma proteins. Other anatomical adaptations in dependent tissues of giraffes represent developmental adjustments to high and variable gravitational forces. These include vascular wall hypertrophy, thickened capillary basement membrane and other connective tissue adaptations. Our results in giraffe suggest avenues of future gravitational research in other animals including humans.

Hargens, Alan R.↗
NASA NTRS2001

Animal model of neuropathic tachycardia syndrome

Clinically relevant autonomic dysfunction can result from either complete or partial loss of sympathetic outflow to effector organs. Reported animal models of autonomic neuropathy have aimed to achieve complete lesions of sympathetic nerves, but incomplete lesions might be more relevant to certain clinical entities. We hypothesized that loss of sympathetic innervation would result in a predicted decrease in arterial pressure and a compensatory increase in heart rate. Increased heart rate due to loss of sympathetic innervation is seemingly paradoxical, but it provides a mechanistic explanation for clinical autonomic syndromes such as neuropathic postural tachycardia syndrome. Partially dysautonomic animals were generated by selectively lesioning postganglionic sympathetic neurons with 150 mg/kg 6-hydroxydopamine hydrobromide in male Sprague-Dawley rats. Blood pressure and heart rate were monitored using radiotelemetry. Systolic blood pressure decreased within hours postlesion (Delta>20 mm Hg). Within 4 days postlesion, heart rate rose and remained elevated above control levels. The severity of the lesion was determined functionally and pharmacologically by spectral analysis and responsiveness to tyramine. Low-frequency spectral power of systolic blood pressure was reduced postlesion and correlated with the diminished tyramine responsiveness (r=0.9572, P=0.0053). The tachycardia was abolished by treatment with the beta-antagonist propranolol, demonstrating that it was mediated by catecholamines acting on cardiac beta-receptors. Partial lesions of the autonomic nervous system have been hypothesized to underlie many disorders, including neuropathic postural tachycardia syndrome. This animal model may help us better understand the pathophysiology of autonomic dysfunction and lead to development of therapeutic interventions.

NASA Discipline Regulatory Physiology↗