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At least 235 records · Page 13

All sources NASA NTRS DOE OSTI

NASA NTRS2005

VEGF165 Stimulates Vessel Density and Vessel Diameter Differently in Angiogenesis and Lymphangiogenesis

Vascular endothelial growth factor-165 (VEGF(sub 165)) stimulated angiogenesis in the quail chorioallantoic membrane (CAM) by vessel expansion from the capillary network. However, lymphangiogenesis was stimulated by the filopodial guidance of tip cells located on blind-ended lymphatic sprouts. As quantified by fractal/generational branching analysis using the computer code VESGEN, vascular density increased maximally at low VEGF concentrations, and vascular diameter increased most at high VEGF concentrations. Increased vascular density and diameter were statistically independent events (r(sub s), -0.06). By fluorescence immunohistochemistry of VEGF receptors VEGFR-1 and VEGFR-2, alpha smooth muscle actin ((alpha) SMA) and a vascular/lymphatic marker, VEGF(sub 165) increased the density and diameter of sprouting lymphatic vessels guided by tip cells (accompanied by the dissociation of lymphatics from blood vessels). Isolated migratory cells expressing (alpha)SMA were recruited to blood vessels, whereas isolated cells expressing VEGFR-2 were recruited primarily to lymphatics. In conclusion, VEGF(sub 165) increased lymphatic vessel density by lymphatic sprouting, but increased blood vessel density by vascular expansion from the capillary network.

Parsons-Wingerter, Patricia↗

NASA NTRS2005

Monolithic Integrated Radiation Sensor Using Stimulated Luminescence From Alumina

The project goal was to design and test a monolithic integrated device for radiation sensing, using optically stimulated luminescence (OSL) from Al2O3:C. The device would consist of GaN/InGaN-based components epitaxially grown on each side of a A12O3:C substrate. Radiation energy stored in the substrate would be stimulated by visible emission from a GaN light-emitting diode (LED) grown on one side of the device, and the OSL emission from the substrate (in the blue region of the spectrum) would be detected by the InGaN pi-n diode grown on the other side of the substrate. The primary application of the device would be in space radiation environments. Thus, two major research thrusts were launched during this project. Firstly, research at Oklahoma State University (Dr. Stephen W.S. McKeever and Dr. E.G. Yukihara) concentrated on characterization of the OSL properties of Al2O3:C in radiation fields typical of those experienced in low-Earth orbit. Secondly, research at the University of Washington (Co-Is, Dr. T.G. Stoebe and Dr. T. Chen) focused of device development and GaN/InGaN epitaxial growth. While progress in each line of research has been substantial, the ultimate goal (that of producing a working prototype device) has not yet been reached. We detail the research progress and identify outstanding issues in this paper.

McKeever, S. W. S.↗

NASA NTRS2004

Effect of gravity on the caloric stimulation of the inner ear

Robert Barany won the 1914 Nobel Prize in medicine for his convection hypothesis for caloric stimulation. Microgravity caloric tests aboard the 1983 SpaceLab 1 mission produced nystagmus results that contradicted the basic premise of Barany's convection theory. In this paper, we present a fluid structural analysis of the caloric stimulation of the lateral semicircular canal. Direct numerical simulations indicate that on earth, natural convection is the dominant mechanism for endolymphatic flow. However, in the microgravity environment of orbiting spacecraft, where buoyancy effects are mitigated, an expansive convection becomes the sole mechanism for producing endolymph motion and cupular displacement. Transient 1 g and microgravity case studies are presented to delineate the different dynamic behaviors of the 1 g and microgravity endolymphatic flows. The associated fluid-structural interactions are also analyzed based on the time evolution of cupular displacements.

Labyrinth/anatomy & histology/physiology↗

NASA NTRS2004

Generation of Electrical Power from Stimulated Muscle Contractions Evaluated

This project is a collaborative effort between NASA Glenn Research Center's Revolutionary Aeropropulsion Concepts (RAC) Project, part of the NASA Aerospace Propulsion and Power Program of the Aerospace Technology Enterprise, and Case Western Reserve University's Cleveland Functional Electrical Stimulation (FES) Center. The RAC Project foresees implantable power requirements for future applications such as organically based sensor platforms and robotics that can interface with the human senses. One of the goals of the FES Center is to develop a totally implantable neural prosthesis. This goal is based on feedback from patients who would prefer a system with an internal power source over the currently used system with an external power source. The conversion system under investigation would transform the energy produced from a stimulated muscle contraction into electrical energy. We hypothesize that the output power of the system will be greater than the input power necessary to initiate, sustain, and control the electrical conversion system because of the stored potential energy of the muscle. If the system can be made biocompatible, durable, and with the potential for sustained use, then the biological power source will be a viable solution.

Lewandowski, Beth↗

NASA NTRS2011

Diagnosis and Treatment of Neurological Disorders by Millimeter-Wave Stimulation

Increasingly, millimeter waves are being employed for telecomm, radar, and imaging applications. To date in the U.S, however, very few investigations on the impact of this radiation on biological systems at the cellular level have been undertaken. In the beginning, to examine the impact of millimeter waves on cellular processes, researchers discovered that cell membrane depolarization may be triggered by low levels of integrated power at these high frequencies. Such a situation could be used to advantage in the direct stimulation of neuronal cells for applications in neuroprosthetics and diagnosing or treating neurological disorders. An experimental system was set up to directly monitor cell response on exposure to continuous-wave, fixed-frequency, millimeter-wave radiation at low and modest power levels (0.1 to 100 safe exposure standards) between 50 and 100 GHz. Two immortalized cell lines derived from lung and neuronal tissue were transfected with green fluorescent protein (GFP) that locates on the inside of the cell membrane lipid bi-layer. Oxonol dye was added to the cell medium. When membrane depolarization occurs, the oxonal bound to the outer wall of the lipid bi-layer can penetrate close to the inner wall where the GFP resides. Under fluorescent excitation (488 nm), the normally green GFP (520 nm) optical signal quenches and gives rise to a red output when the oxonol comes close enough to the GFP to excite a fluorescence resonance energy transfer (FRET) with an output at 620 nm. The presence of a strong FRET signature upon exposures of 30 seconds to 2 minutes at 5-10 milliwatts per square centimeter RF power at 50 GHz, followed by a return to the normal 520-nm GFP signal after a few minutes indicating repolarization of the membrane, indicates that low levels of RF energy may be able to trigger non-destructive membrane depolarization without direct cell contact. Such a mechanism could be used to stimulate neuronal cells in the cortex without the need for invasive electrodes as millimeter waves penetrate skin and bone on the order of 15 mm in depth. Although 50 GHz could not readily penetrate from the outer skull to the center of the cortex, implants on the outer skull or even on the scalp could reach the outer layer of the cerebral cortex where substantial benefit could be realized from such non-contact type excitation.

Siegel, Peter H.↗

NASA NTRS2011

Spectral Interpretation of Radio Sounder-Stimulated Magnetospheric Plasma Resonances in Terms of Kappa Distributions

Magnetosphere sounders stimulate plasma resonances between the harmonics of the electron cyclotron frequency and above the upper-hybrid frequency. More than three decades ago they were recognized as equivalent to ionospheric topside-sounder-stimulated resonances, designated as Qn resonances a decade earlier, with one important difference: the magnetospheric Qn frequencies often indicated that the background electron-velocity distribution was non-Maxwellian. Interpretations based on bi-Maxwellian and kappa distributions have been proposed. Here we expand on the latter, which requires fewer free parameters, by comparing kappa-derived Qn frequencies with observations from the Radio Plasma Imager on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite.

Benson, Robert F.↗

NASA NTRS2012

Improving Balance Function Using Low Levels of Electrical Stimulation of the Balance Organs

Crewmembers returning from long-duration space flight face significant challenges due to the microgravity-induced inappropriate adaptations in balance/ sensorimotor function. The Neuroscience Laboratory at JSC is developing a method based on stochastic resonance to enhance the brain s ability to detect signals from the balance organs of the inner ear and use them for rapid improvement in balance skill, especially when combined with balance training exercises. This method involves a stimulus delivery system that is wearable/portable providing imperceptible electrical stimulation to the balance organs of the human body. Stochastic resonance (SR) is a phenomenon whereby the response of a nonlinear system to a weak periodic input signal is optimized by the presence of a particular non-zero level of noise. This phenomenon of SR is based on the concept of maximizing the flow of information through a system by a non-zero level of noise. Application of imperceptible SR noise coupled with sensory input in humans has been shown to improve motor, cardiovascular, visual, hearing, and balance functions. SR increases contrast sensitivity and luminance detection; lowers the absolute threshold for tone detection in normal hearing individuals; improves homeostatic function in the human blood pressure regulatory system; improves noise-enhanced muscle spindle function; and improves detection of weak tactile stimuli using mechanical or electrical stimulation. SR noise has been shown to improve postural control when applied as mechanical noise to the soles of the feet, or when applied as electrical noise at the knee and to the back muscles.

Bloomberg, Jacob↗

NASA NTRS2013

Application of electrical stimulation for functional tissue engineering in vitro and in vivo

The present invention provides new methods for the in vitro preparation of bioartificial tissue equivalents and their enhanced integration after implantation in vivo. These methods include submitting a tissue construct to a biomimetic electrical stimulation during cultivation in vitro to improve its structural and functional properties, and/or in vivo, after implantation of the construct, to enhance its integration with host tissue and increase cell survival and functionality. The inventive methods are particularly useful for the production of bioartificial equivalents and/or the repair and replacement of native tissues that contain electrically excitable cells and are subject to electrical stimulation in vivo, such as, for example, cardiac muscle tissue, striated skeletal muscle tissue, smooth muscle tissue, bone, vasculature, and nerve tissue.

Radisic, Milica↗

NASA NTRS2014

Improving Sensorimotor Function and Adaptation using Stochastic Vestibular Stimulation

Astronauts experience sensorimotor changes during adaption to G-transitions that occur when entering and exiting microgravity. Post space flight, these sensorimotor disturbances can include postural and gait instability, visual performance changes, manual control disruptions, spatial disorientation, and motion sickness, all of which can hinder the operational capabilities of the astronauts. Crewmember safety would be significantly increased if sensorimotor changes brought on by gravitational changes could be mitigated and adaptation could be facilitated. The goal of this research is to investigate and develop the use of electrical stochastic vestibular stimulation (SVS) as a countermeasure to augment sensorimotor function and facilitate adaptation. For this project, SVS will be applied via electrodes on the mastoid processes at imperceptible amplitude levels. We hypothesize that SVS will improve sensorimotor performance through the phenomena of stochastic resonance, which occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. In line with the theory of stochastic resonance, a specific optimal level of SVS will be found and tested for each subject [1]. Three experiments are planned to investigate the use of SVS in sensory-dependent tasks and performance. The first experiment will aim to demonstrate stochastic resonance in the vestibular system through perception based motion recognition thresholds obtained using a 6-degree of freedom Stewart platform in the Jenks Vestibular Laboratory at Massachusetts Eye and Ear Infirmary. A range of SVS amplitudes will be applied to each subject and the subjectspecific optimal SVS level will be identified as that which results in the lowest motion recognition threshold, through previously established, well developed methods [2,3,4]. The second experiment will investigate the use of optimal SVS in facilitating sensorimotor adaptation to system disturbances. Subjects will adapt to wearing minifying glasses, resulting in decreased vestibular ocular reflex (VOR) gain. The VOR gain will then be intermittently measured while the subject readapts to normal vision, with and without optimal SVS. We expect that optimal SVS will cause a steepening of the adaptation curve. The third experiment will test the use of optimal SVS in an operationally relevant aerospace task, using the tilt translation sled at NASA Johnson Space Center, a test platform capable of recreating the tilt-gain and tilt-translation illusions associated with landing of a spacecraft post-space flight. In this experiment, a perception based manual control measure will be used to compare performance with and without optimal SVS. We expect performance to improve in this task when optimal SVS is applied. The ultimate goal of this work is to systematically investigate and further understand the potential benefits of stochastic vestibular stimulation in the context of human space flight so that it may be used in the future as a component of a comprehensive countermeasure plan for adaptation to G-transitions.

Galvan, R. C.↗

NASA NTRS2016

Ocular Vestibular Evoked Myogenic Potentials Using Head Striker Stimulation

Introduction: Over the last two decades, several studies have been published on the impact of long-duration (i.e., 22 days or longer) spaceflight on the central nervous system (CNS). In consideration of the health and performance of crewmembers in flight and post-flight, we are conducting a controlled prospective longitudinal study to investigate the effects of spaceflight on the extent, longevity and neural bases of sensorimotor, cognitive, and neural changes. Multiple studies have demonstrated the effects of spaceflight on the vestibular system. One of the supporting tests conducted in this protocol is the Vestibular Evoked Myogenic Potential (VEMP) test that provides a unilateral measure of otolith (saccule and utricle) function. A different approach was taken for ocular VEMP (oVEMP) testing using a head striker system (Wackym et al. 2012). The oVEMP is generally considered to be a measure of utricle function. The the otolithic input to the inferior oblique muscle is predominately from the utricular macula. Thus, quantitatively, oVEMP tests utricular function. Another practical extension of these relationships is that the oVEMP reflects the superior vestibular nerve function. Methods: Ground testing was administered on 16 control subjects and for 8 subjects over four repeated sessions spanning 70 days. The oVEMP was elicitied via a hand held striker by a vibrotactile pulse presented at the rate of 1 Hz for 24 seconds on the side of the head as subjects lay supine on a gurney. Subjects were directed to gaze approximately 25 degrees above straight ahead in semi-darkness. For the oVEMP electromyograms will be recorded with active bipolar electrodes (Delsys Inc., Boston, MA) on the infra-orbital ridge 1 cm below the eyelid with a reference electrode on the below the knee cap. The EMG potentials were amplified; band-pass filtered using a BagnoliTM Desktop EMG System (Delsys Inc., Boston, MA, USA). This EMG signal is sampled at 10 kHz and the data stimulus onset to 100 MS was averaged over 24 trial repetitions for the vibrotactile VEMP. The typical oVEMP EMG response is an excitatory potential with first peak occurring at 11-12 ms and second peak at 18 ms. This requires a total recording time of approximately 29 seconds per trial which includes 5 seconds of no vibrotactile stimulation at the beginning of the protocol. The primary dependent measures consist of the latency and peak-to-peak amplitude from the EMG signals, which will be normalized to EMG levels at the beginning of the protocol. Data were collected for 3 repeated trials with striker stimulation on both the left and right side of the head Results: The oVEMP p1 range was observed at 3-14 ms and n1 at 7-19 ms. The striker system provided a consistent and rapid method for oVEMP testing. Discussion: Crew testing is in progress to determine changes in results between pre and post flight.

De Dios, Y. E.↗

NASA NTRS2016

Efficacy of Stochastic Vestibular Stimulation to Improve Locomotor Performance in a Discordant Sensory Environment

Astronauts exposed to microgravity face sensorimotor challenges incurred when readapting to a gravitational environment. Sensorimotor Adaptability (SA) training has been proposed as a countermeasure to improve locomotor performance during re-adaptation, and it is suggested that the benefits of SA training may be further enhanced by improving detection of weak sensory signals via mechanisms such as stochastic resonance when a non-zero level of stochastic white noise based electrical stimulation is applied to the vestibular system (stochastic vestibular stimulation, SVS). The purpose of this study was to test the efficacy of using SVS to improve short-term adaptation in a sensory discordant environment during performance of a locomotor task.

Temple, D. R.↗

NASA NTRS2018

Genetic Regulation of Bone and Cells by Electromagnetic Stimulation Fields and Uses Thereof

The present invention provides methods to modify the genetic regulation of mammalian tissue, bone, cells or any combination thereof by preferential activation, up-regulation and/or down-regulation. The method comprises steps of tuning the predetermined profiles of one or more time-varying stimulation fields by manipulating the B-Field magnitude, rising slew rate, rise time, falling slew rate, fall time, frequency, wavelength, and duty cycle, and exposing mammalian cells or tissues to one or more tuned time-varying stimulation fields with predetermined profiles. Examples of mammalian cells or tissues are chondrocytes, osteoblasts, osteocytes, osteoclasts, nucleus pulposus, associated tissue, or any combination. The resulted modification on gene regulation of these cells, tissues or bones may promote the retention, repair of and reduction of compromised mammalian cartilage, bone, and associated tissue.

Goodwin, Thomas J.↗

NASA NTRS2025

Orion Hardware In The Loop OIMU Stimulation Latency Effect on Navigation State Estimation

Because Hardware In The Loop (HITL) testing involves the integration of flight software and flight hardware on the ground, non-flight-like effects may arise. One of these non-flight-like effects includes Inertial Measurement Unit (IMU) stimulation latency that affects the time in which the measurement is received by the Extended Kalman Filter (EKF). This paper seeks to present the extent to which this stimulation latency affects the navigational state estimate from the Orion navigation system for all phases of flight for Artemis II.

Christopher A Ertl↗

NASA NTRSDate not supplied

Orion Hardware In The Loop OIMU Stimulation Latency Effect on Navigation State Estimation

Christopher A Ertl↗

DOE OSTI2021

Tracer Testing to Characterize Hydraulic Stimulation Experiments at the Raft River EGS Demonstration Site

A series of three tracer tests was conducted over a 3.5-year period as part of the Raft River EGS Demonstration Project in order to characterize the evolution of fluid flow processes resulting from the hydraulic stimulation of the target injection well RRG-9. Injectivity increased very little in RRG-9 as the result of hydraulic stimulation experiments over a 300-day period but increased significantly as brine was injected continuously over the subsequent three years. Here, the tracer tests revealed that fluid flow patterns evolved over time along the injection/production pathway with tracer breaking through progressively earlier and to more wells over the duration of the testing.

EGS↗

DOE OSTI2023

Implantable neuromodulation system for closed-loop stimulation and recording simultaneously at multiple brain sets

The present disclosure relates to a modular system for deep brain stimulation (DBS) and electrocorticography (ECoG). The system may have an implantable neuromodulator for generating electrical stimulation signals adapted to be applied to a desired region of a brain via an attached electrode array. An aggregator module may be used for collecting and aggregating electrical signals and transmitting the electrical signals to the neuromodulator. A control module may be used which is in communication with the aggregator module for controlling generation of the electrical signals and transmitting the electrical signals to the aggregator.

Pannu, Satinderpall S.↗

DOE OSTI2022

Utah FORGE: Seismic Event Catalogue from the April, 2022 Stimulation of Well 16A(78)-32

This dataset includes earthquake catalogues for the three stages of the 2022 well 16A(78)-32 stimulation provided by Geo Energie Suisse. Events in these catalogues have been visually inspected. There are additional events of lower signal to noise that were automatically detected. Those events will require additional analysis and processing. Times are recorded in UTC (Coordinate Universal Time), and the coordinate reference system is UTM Zone 12N, NAD83.

15 GEOTHERMAL ENERGY↗

DOE OSTI2022

Utah FORGE: Well 16A(78)-32 Stimulation Tracer Test Results

This archive contains data from the tracer test performed during the Utah FORGE well 16A(78)-32 stimulation. This includes: 1. the raw data file from Pason in the csv format; 2. a one-page Word document from Pason that explains the headers and units used in their data file; 3. an Excel spreadsheet with concentration data and relevant Pason flow data; 4. a Word document with jpg versions of concentration charts (Figs. 1-3) and a tracer mass recovery chart (Fig. 4).

15 GEOTHERMAL ENERGY↗