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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Proposed application of lower body negative pressure to cardiology

Potential medical applications are presented of lower body negative pressure to the evaluation and treatment of cardiac patients. The essential features of an LBNP unit and the basic cardiovascular physiology of lower body negative pressure (LBNP) testing are described. Some of the results of previous spaceflight experiences and bedrest studies are summarized. The deconditioning effects of weightlessness experienced by orbiting astronauts are compared with the effects of bedrest restrictions prescribed for convalescing cardiac patients. The potential of LBNP for evaluating both pharmacological and physical activity regimens was examined, particularly in relation to post-myocardial infarction and coronary artery bypass patients. Applications of LBNP to the cardiac catheterization laboratory and the out-patient follow-up of cardiac patients are proposed.

E. V. Schmidt↗
NASA NTRS1988

USSR Space Life Sciences Digest, issue 15

This is the 15th issue of NASA's USSR Space Life Sciences Digest. It contains abstracts of 59 papers published in Russian language periodicals or presented at conferences and of two new Soviet monographs. Selected abstracts are illustrated with figures and tables from the original. An additional feature is a review of a conference devoted to the physiology of extreme states. The abstracts included in this issue have been identified as relevant to 29 areas of space biology and medicine. These areas are adaptation, biological rhythms, biospherics, body fluids, botany, cardiovascular and respiratory systems, endocrinology, enzymology, equipment and instrumentation, exobiology, genetics, habitability and environment effects, human performance, immunology, life support systems, mathematical modeling, metabolism, microbiology, musculoskeletal system, neurophysiology, nutrition, operational medicine, perception. personnel selection, psychology, radiobiology, reproductive biology, and space biology and medicine.

Hooke, Lydia Razran↗
NASA NTRS1993

Exercise countermeasure protocol management expert system

Exercise will be used primarily to countermeasure against deconditioning on extended space flight. In this paper we describe the development and evaluation of an expert system for exercise countermeasure protocol management. Currently, the system includes two major subsystems: baseline prescription and prescription adjustment. The baseline prescription subsystem is designed to provide initial exercise prescriptions while prescription adjustment subsystem is designed to modify the initial prescription based on the exercised progress. The system runs under three different environments: PC, SUN workstation, and Symbolic machine. The inference engine, baseline prescription module, prescription adjustment module and explanation module are developed under the Symbolic environment by using the ART (Automated Reasoning Tool) software. The Sun environment handles database management features and interfaces with PC environment to obtain physical and physiological data from exercise units on-board during the flight. Eight subjects' data have been used to evaluate the system performance by comparing the prescription of nine experienced exercise physiologists and the one prescribed by the expert system. The results of the validation test indicated that the performance of the expert system was acceptable.

NASA Discipline Data Analysis↗
NASA NTRS1987

Nonlinear dynamics, fractals, cardiac physiology and sudden death

The authors propose a diametrically opposite viewpoint to the generally accepted tendency of equating healthy function with order and disease with chaos. With regard to the question of sudden cardiac death and chaos, it is suggested that certain features of dynamical chaos related to fractal structure and fractal dynamics may be important organizing principles in normal physiology and that certain pathologies, including ventricular fibrillation, represent a class of 'pathological periodicities'. Some laboratory work bearing on the relation of nonlinear analysis to physiological and pathophysiological data is briefly reviewed, with tentative theories and models described in reference to the mechanism of ventricular fibrillation.

Goldberger, Ary L.↗
NASA NTRS1991

The biogeochemistry of microbial mats, stromatolites and the ancient biosphere

Stromatolites offer an unparalleled geologic record of early life, because they constitute the oldest and most abundant recognizable remains of microbial ecosystems. Microbial mats are living homologs of stromatolites; thus, the physiology of the microbiota as well as the processes which create those features of mats (e.g., biomarker organic compounds, elemental and stable isotopic compositions) which are preserved in the ancient record. Observations of the carbon isotopic composition (delta C-13) of stromatolites and microbial mats were made and are consistent with the hypothesis that atmospheric CO2 concentrations have declined by at least one to two orders of magnitude during the past 2.5 Ga. Whereas delta C-13 values of carbonate carbon average about 0 permil during both the early and mid-Proterozoic, the delta C-13 values of stromatolitic organic matter increase from an average of -35 between 2.0 and 2.6 Ga ago to an average of about -28 about 1.0 Ga ago. Modern microbial mats in hypersaline environments have delta C-13 values typically in the range of -5 to -9, relative to an inorganic bicarbonate source at 0 permil. Both microbial mats and pur cultures of cyanobacteria grown in waters in near equilibrium with current atmospheric CO2 levels exhibit minimal discrimination against C-13. In contrast, hot spring cyanobacterial mats or cyanobacterial cultures grown under higher CO2 levels exhibit substantially greater discrimination. If care is taken to compare modern mats with stromatolites from comparable environments, it might be possible to estimate ancient levels of atmospheric CO2. In modern microbial mats, a tight coupling exists between photosynthetic organic carbon production and subsequent carbon oxidation, mostly by sulfate reduction. The rate of one process fuels a high rate of the other, with much of the sulfate reduction occurring within the same depth interval as oxygenic photosynthesis. Other aspects of this study are presented.

Desmarais, D. J.↗
NASA NTRS1971

Measurements, modeling, control and simulation - as applied to the human left ventricle for purposeful physiological monitoring.

Interdisciplinary engineering research effort in studying the intact human left ventricle has been employed to physiologically monitor the heart and to obtain its 'state-of-health' characteristics. The left ventricle was selected for this purpose because it plays a key role in supplying energy to the body cells. The techniques for measurement of the left ventricular geometry are described; the geometry is effectively displayed to bring out the abnormalities in cardiac function. Methods of mathematical modeling, which make it possible to determine the performance of the intact left ventricular muscle, are also described. Finally, features of a control system for the left ventricle for predicting the effect of certain physiological stress situations on the ventricle performance are discussed.

Ghista, D. N.↗
NASA NTRS2010

Biosensors for EVA: Improved Instrumentation for Ground-based Studies

During lunar excursions in the EVA suit, real-time measurement of metabolic rate is required to manage consumables and guide activities to ensure safe return to the base. Metabolic rate, or oxygen consumption (VO2), is normally measured from pulmonary parameters but cannot be determined with standard techniques in the oxygen-rich environment of a spacesuit. Our group has developed novel near infrared spectroscopic (NIRS) methods to calculate muscle oxygen saturation (SmO 2), hematocrit, and pH, and we recently demonstrated that we can use our NIRS sensor to measure VO 2 on the leg during cycling. Our NSBRI project has 4 objectives: (1) increase the accuracy of the metabolic rate calculation through improved prediction of stroke volume; (2) investigate the relative contributions of calf and thigh oxygen consumption to metabolic rate calculation for walking and running; (3) demonstrate that the NIRS-based noninvasive metabolic rate methodology is sensitive enough to detect decrement in VO 2 in a space analog; and (4) improve instrumentation to allow testing within a spacesuit. Over the past year we have made progress on all four objectives, but the most significant progress was made in improving the instrumentation. The NIRS system currently in use at JSC is based on fiber optics technology. Optical fiber bundles are used to deliver light from a light source in the monitor to the patient, and light reflected back from the patient s muscle to the monitor for spectroscopic analysis. The fiber optic cables are large and fragile, and there is no way to get them in and out of the test spacesuit used for ground-based studies. With complimentary funding from the US Army, we undertook a complete redesign of the sensor and control electronics to build a novel system small enough to be used within the spacesuit and portable enough to be used by a combat medic. In the new system the filament lamp used in the fiber optic system was replaced with a novel broadband near infrared LED light source. The compact grating spectrometer was replaced with a chip-scale spectrometer. With this new design, the sensor is 4 in 2 in 0.5 in, weighs 60 g, and no fiber optic cables are needed. The sensor, which contains the light source and the spectrometer, is adhered directly to the skin with medical grade adhesive. The sensor can be powered via the USB port of the laptop computer that controls the sensor operation. Alternatively, for studies in the spacesuit, the sensor can be powered by a small battery pack and operated by an ultra-portable hand-held computer. Both the handheld computer and battery pack will easily fit within the PLSS of the test spacesuit. System automation was significantly improved, to add features suggested by our colleagues in the Cardiovascular Laboratory and the NASA JSC Exercise Physiology and Countermeasures Project. The functionality and portability of this system were demonstrated in our UMass laboratory.

Soller, B.↗
NASA NTRSDate not supplied

Oxidative Stress and the Neuroconsequences of Spaceflight Environment - Immune Dysregulation and Antioxidant Dietary Countermeasure Efficacy

In this project, we will test the hypothesis that Ionizing Radiation (IR), microgravity and social isolation combine synergistically to trigger an oxidative stress response that alters immune homeostasis, brain structure and function, and neurobehavioral and cognitive performance. Specific Aims for this project are: (1) Determine dose-response curves for acute ‘Five-Ion GCR Simulation’ exposure for immune, brain and performance responses in crew age-matched adult male and female mice; (2) Determine effects of acute ‘Five-Ion GCR Simulation’ exposure singly and in combination with simulated microgravity and social isolation, on immune, brain and performance responses in crew age-matched male and female mice mimicking deep space missions; and (3) Determine efficacy of the dietary antioxidant, Nicotinamide Mononucleotide (NMN), a key intermediate in nicotinamide adenine dinucleotide (NAD+) biosynthesis. The project relies on established and highly translatable ground-based mouse models and assays with IR exposures to be performed at the NASA Space Radiation Laboratory (NSRL). The experimental approach will provide definitive data on the timing and mechanisms involved in the oxidative stress response, immune and brain changes, and ensuing functional (behavioral/cognitive) impairments expected during human transit to Mars. This project will identify potential biomarkers for, and mechanisms underlying, structural and functional changes in the immune and nervous systems leading to behavioral/cognitive performance deficits, and its potential application to develop effective countermeasures to mitigate negative health effects of long duration space habitation. The project will address NASA’s efforts to rapidly advance the characterization of risks and identify appropriate countermeasures in anticipation of future deep space missions. Ensuring crew health and performance during extended transits necessitates that sensorimotor and cognitive abilities remain strong to avoid potentially catastrophic health and safety outcomes. Further, despite historically low numbers of female astronauts, the two most recent NASA Astronaut Corps class selections, comprised of ~50% women as compared to men, signal the need to understand how sex differences affect physiological adaptation and health in the space environment. Here, we will determine how key features of the deep space environment may interact to increase risk to crewmembers by negatively impacting health and performance, and identify and develop strategies to characterize and mitigate the potential risks via countermeasures. Supported by the NASA Human Research Program (HRP) Human Factors Behavioral Performance Element Grant 18-18FLAG_2-0028.

radiation↗
NASA NTRS1993

Adaptation of Baroreflexes and Orthostatic Hypotension

The footward shift of blood volume and compensatory autonomic reflex responses initiated during the assumption of the upright posture in terrestrial gravity is a common feature in humans. When regular exposure to upright posture is removed, the headward redistribution of blood induces numerous physiological adaptations which compromise this normal response and the development of low blood pressure upon standing (orthostatic hypotension) can ensue. Such microgravity conditions can be produced by prolonged exposure to spaceflight or prolonged bed rest. Since the reduction of blood and plasma volume during exposure to microgravity has been associated with orthostatic instability following spaceflight and bed rest, it has been a reasonable assumption that hypovolemia may be a primary contributing factor to the development of orthostatic hypotension. This view was supported by the observation that the attempt to restore vascular volume in astronauts by drinking saline solutions just prior to re-entry had proven effective in reducing orthostatic instability after spaceflights of short duration. However, as the duration of spaceflight lengthens, orthostatic instability persists despite fluid loading procedures, suggesting that mechanisms other than hypovolemia may contribute to orthostatic hypotension following prolonged exposure to microgravity conditions. Recent evidence has been generated from spaceflight and groundbase experiments that supports the notion that changes in autonomic baroreflexes that control cardiac and vascular responses during orthostatic challenges may be affected by longer periods of microgravity exposure and can contribute to postflight orthostatic instability.

Convertino, Victor A.↗
NASA NTRS2011

Optimizing Muscle Parameters in Musculoskeletal Modeling Using Monte Carlo Simulations

Astronauts assigned to long-duration missions experience bone and muscle atrophy in the lower limbs. The use of musculoskeletal simulation software has become a useful tool for modeling joint and muscle forces during human activity in reduced gravity as access to direct experimentation is limited. Knowledge of muscle and joint loads can better inform the design of exercise protocols and exercise countermeasure equipment. In this study, the LifeModeler(TM) (San Clemente, CA) biomechanics simulation software was used to model a squat exercise. The initial model using default parameters yielded physiologically reasonable hip-joint forces. However, no activation was predicted in some large muscles such as rectus femoris, which have been shown to be active in 1-g performance of the activity. Parametric testing was conducted using Monte Carlo methods and combinatorial reduction to find a muscle parameter set that more closely matched physiologically observed activation patterns during the squat exercise. Peak hip joint force using the default parameters was 2.96 times body weight (BW) and increased to 3.21 BW in an optimized, feature-selected test case. The rectus femoris was predicted to peak at 60.1% activation following muscle recruitment optimization, compared to 19.2% activation with default parameters. These results indicate the critical role that muscle parameters play in joint force estimation and the need for exploration of the solution space to achieve physiologically realistic muscle activation.

Hanson, Andrea↗
NASA NTRS1996

Latency and activation in the control of TGF-beta

The biological activity of the transforming growth factor-beta's (TGF-beta)3 is tightly controlled by their persistence in the extracellular compartment as latent complexes. Each of the three mammalian isoform genes encodes a product that is cleaved intracellularly to form two polypeptides, each of which dimerizes. Mature TGF-beta, a 24 kD homodimer, is noncovalently associated with the 80 kD latency-associated peptide (LAP). LAP is a fundamental component of TGF-beta that is required for its efficient secretion, prevents it from binding to ubiquitous cell surface receptors, and maintains its availability in a large extracellular reservoir that is readily accessed by activation. This latent TGF-beta complex (LTGF-beta) is secreted by all cells and is abundant both in circulating forms and bound to the extracellular matrix. Activation describes the collective events leading to the release of TGF-beta. Despite the importance of TGF-beta regulation of growth and differentiation in physiological and malignant tissue processes, remarkably little is known about the mechanisms of activation in situ. Recent studies of irradiated mammary gland reveal certain features of TGF-beta 1 activation that may shed light on its regulation and potential roles in the normal and neoplastic mammary gland.

Non-NASA Center↗
NASA NTRS1980

Blood circulation under conditions of weightlessness

Experimental materials and published data on the problem of blood circulation in man and animals under conditions of short and long term weightlessness are summarized. The data obtained allow the conclusion, that when humans spent 5 days in a weightless state their blood circulation was not essentially distributed. Some features of the functioning of the cardiovascular system are pointed out: delay of adaptation rate, increase in lability, etc. There is a discussion of the physiological mechanisms for the direct and indirect effect of weightlessness. The direct effect comprise the complex of reactions caused by the significant fall in hydrostatic pressure and the indirect embraces all the reactions arising in the organism resulting from disturbance of the systematic character of the analyzers that take part in the analysis of space realtions and the body's orientation in space.

Kastyan, I. I.↗
NASA NTRS1975

The auditory neural network in man

The principles of anatomy and physiology necessary for understanding brain wave recordings made from the scalp are briefly discussed. Brain waves evoked by sounds are then described and certain of their features are related to the physical aspects of the stimulus and the psychological state of the listener. It is proposed that data obtained through probes located outside the head can reveal a large amount of detail about brain activity. It is argued that analysis of such records enables one to detect the response of the nervous system to an acoustic message at the moment of its inception at the ear, and to follow the progress of the acoustic message up through the various brain levels as progressively more complex operations are performed upon it. Even those brain events responsible for the highest level of signal processing - distinguishing between similar signals and making decisions about them - seem to generate characteristic and identifiable electrical waves.

Galambos, R.↗
NASA NTRS2002

Basal glycogenolysis in mouse skeletal muscle: in vitro model predicts in vivo fluxes

A previously published mammalian kinetic model of skeletal muscle glycogenolysis, consisting of literature in vitro parameters, was modified by substituting mouse specific Vmax values. The model demonstrates that glycogen breakdown to lactate is under ATPase control. Our criteria to test whether in vitro parameters could reproduce in vivo dynamics was the ability of the model to fit phosphocreatine (PCr) and inorganic phosphate (Pi) dynamic NMR data from ischemic basal mouse hindlimbs and predict biochemically-assayed lactate concentrations. Fitting was accomplished by optimizing four parameters--the ATPase rate coefficient, fraction of activated glycogen phosphorylase, and the equilibrium constants of creatine kinase and adenylate kinase (due to the absence of pH in the model). The optimized parameter values were physiologically reasonable, the resultant model fit the [PCr] and [Pi] timecourses well, and the model predicted the final measured lactate concentration. This result demonstrates that additional features of in vivo enzyme binding are not necessary for quantitative description of glycogenolytic dynamics.

Non-NASA Center↗
NASA NTRS2012

Performance Requirements for Emergency Responder Interoperable and Compatible Electronic Safety Equipment

Firefighters and other emergency response personnel are presented with an increasing array of technologies to improve their health and safety. This includes real-time bidirectional communication, navigation and positional information, data on physiological and metabolic functions, as well as data on their surrounding environment. The emerging challenge is to integrate these elements into a practical system, addressing such features as power, data transfer, and inter-element coordination and communication. In many respects, NASA has addressed these aspects in the context of Extra Vehicular Activity (EVA). The EVA environment shares many common attributes with that of emergency response scenarios. A similar situation exists in terms of the need for interoperability among the various system sub-elements. A brief overview is presented on the similarities and differences in these two applications, as well as the technical approach adopted by NASA in terms of system design philosophy.

Greenberg, Paul S.↗
NASA NTRS1985

Structure and physiology of Beggiatoa and Thiothrix

Reggiatoa and Thiothrix are genera of filamentous, colorless, sulfide oxidizing bacteria. These organisms are microaerophilic, oxidizing sulfide to sulfur in the presence of oxygen. The sulfur accumulates in intracellular sulfur globules - the outstanding morphological feature of these bacteria. Some strains are able to further oxidize the sulfur to sulfate aerobically or reduce the sulfur to sulfide anaerobically. This metabolic versatility makes these bacteria important links in aquatic sulfur cycles.

Schmidt, T. M.↗
NASA NTRS1975

The auditory neural network in man

The principles of anatomy and physiology necessary for understanding brain wave recordings made from the scalp of normal people are briefly discussed. Brain waves evoked by sounds are described and certain of their features are related to the physical aspects of the stimulus and to the psychological state of the listener. The position is taken that data obtained through scalp probes can reveal a large amount of detail about brain functioning and that analysis of such records enable detection of the response of the nervous system to an acoustic message at the moment of its inception and to the progress of the message through the brain. Brain events responsible for distinguishing between similar signals and making decisions about them appear to generate characteristic and identifiable electrical waves. Some theoretical speculation about these data are introduced with the aim of generating a more heuristic model of the functioning brain.

Galambos, R.↗