WorldWideScience

Sample records for impact spacecraft eyes

  1. Low power arcjet system spacecraft impacts

    Science.gov (United States)

    Pencil, Eric J.; Sarmiento, Charles J.; Lichtin, D. A.; Palchefsky, J. W.; Bogorad, A. L.

    1993-01-01

    Potential plume contamination of spacecraft surfaces was investigated by positioning spacecraft material samples relative to an arcjet thruster. Samples in the simulated solar array region were exposed to the cold gas arcjet plume for 40 hrs to address concerns about contamination by backstreaming diffusion pump oil. Except for one sample, no significant changes were measured in absorptance and emittance within experimental error. Concerns about surface property degradation due to electrostatic discharges led to the investigation of the discharge phenomenon of charged samples during arcjet ignition. Short duration exposure of charged samples demonstrated that potential differences are consistently and completely eliminated within the first second of exposure to a weakly ionized plume. The spark discharge mechanism was not the discharge phenomenon. The results suggest that the arcjet could act as a charge control device on spacecraft.

  2. Impact of dry eye on work productivity

    Directory of Open Access Journals (Sweden)

    Yamada M

    2012-10-01

    Full Text Available Masakazu Yamada, Yoshinobu Mizuno, Chika ShigeyasuNational Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, JapanBackground: The purpose of this study was to evaluate the impact of dry eye on work productivity of office workers, especially in terms of presenteeism.Methods: A total of 396 individuals aged ≥20 years (258 men and 138 women, mean age 43.4 ± 13.0 years were recruited through an online survey. Data from 355 responders who did not have missing values were included in the analysis. They were classified into the following four groups according to the diagnostic status and subjective symptoms of dry eye: a definite dry eye group; a marginal dry eye group; a self-reported dry eye group; and a control group. The impact of dry eye on work productivity was evaluated using the Japanese version of the Work Limitations Questionnaire. The cost of work productivity loss associated with dry eye and the economic benefits of providing treatment for dry eye were also assessed.Results: The degree of work performance loss was 5.65% in the definite dry eye group, 4.37% in the marginal dry eye group, 6.06% in the self-reported dry eye group, and 4.27% in the control group. Productivity in the self-reported dry eye group was significantly lower than that in the control group (P < 0.05. The annual cost of work productivity loss associated with dry eye was estimated to be USD 741 per person.Conclusion: Dry eye impairs work performance among office workers, which may lead to a substantial loss to industry. Management of symptoms of dry eye by providing treatment may contribute to improvement in work productivity.Keywords: burden of disease, dry eye, presenteeism, quality of life

  3. Impact of dry eye on work productivity.

    Science.gov (United States)

    Yamada, Masakazu; Mizuno, Yoshinobu; Shigeyasu, Chika

    2012-01-01

    The purpose of this study was to evaluate the impact of dry eye on work productivity of office workers, especially in terms of presenteeism. A total of 396 individuals aged ≥20 years (258 men and 138 women, mean age 43.4 ± 13.0 years) were recruited through an online survey. Data from 355 responders who did not have missing values were included in the analysis. They were classified into the following four groups according to the diagnostic status and subjective symptoms of dry eye: a definite dry eye group; a marginal dry eye group; a self-reported dry eye group; and a control group. The impact of dry eye on work productivity was evaluated using the Japanese version of the Work Limitations Questionnaire. The cost of work productivity loss associated with dry eye and the economic benefits of providing treatment for dry eye were also assessed. The degree of work performance loss was 5.65% in the definite dry eye group, 4.37% in the marginal dry eye group, 6.06% in the self-reported dry eye group, and 4.27% in the control group. Productivity in the self-reported dry eye group was significantly lower than that in the control group (P work productivity loss associated with dry eye was estimated to be USD 741 per person. Dry eye impairs work performance among office workers, which may lead to a substantial loss to industry. Management of symptoms of dry eye by providing treatment may contribute to improvement in work productivity.

  4. Evaluating Fault Management Operations Concepts for Next-Generation Spacecraft: What Eye Movements Tell Us

    Science.gov (United States)

    Hayashi, Miwa; Ravinder, Ujwala; McCann, Robert S.; Beutter, Brent; Spirkovska, Lily

    2009-01-01

    Performance enhancements associated with selected forms of automation were quantified in a recent human-in-the-loop evaluation of two candidate operational concepts for fault management on next-generation spacecraft. The baseline concept, called Elsie, featured a full-suite of "soft" fault management interfaces. However, operators were forced to diagnose malfunctions with minimal assistance from the standalone caution and warning system. The other concept, called Besi, incorporated a more capable C&W system with an automated fault diagnosis capability. Results from analyses of participants' eye movements indicate that the greatest empirical benefit of the automation stemmed from eliminating the need for text processing on cluttered, text-rich displays.

  5. Electromagnetic Effices from Impacts on Spacecraft

    Science.gov (United States)

    Close, Sigrid

    2018-04-01

    Hypervelocity micro particles, including meteoroids and space debris with masses electromagnetic pulse (EMP) with a broad frequency spectrum. Subsequent plasma oscillations resulting from instabilities can also emit significant power and may be responsible for many reported satellite anomalies. We present theory and recent results from ground-based impact tests aimed at characterizing hypervelocity impact plasma and show that impact-produced radio frequency (RF) emissions occurred in frequencies ranging from VHF through L-band and that these emissions were highly correlated with fast (> 20 km/s) impacts that produced a fully ionized plasma.

  6. Laboratory investigation of antenna signals from dust impacts on spacecraft

    Science.gov (United States)

    Sternovsky, Zoltan; Collette, Andrew; Malaspina, David M.; Thayer, Frederick

    2016-04-01

    Electric field and plasma wave instruments act as dust detectors picking up voltage pulses induced by impacts of particulates on the spacecraft body. These signals enable the characterization of cosmic dust environments even with missions without dedicated dust instruments. For example, the Voyager 1 and 2 spacecraft performed the first detection of dust particles near Uranus, Neptune, and in the outer solar system [Gurnett et al., 1987, 1991, 1997]. The two STEREO spacecraft observed distinct signals at high rate that were interpreted as nano-sized particles originating from near the Sun and accelerated to high velocities by the solar wind [MeyerVernet et al, 2009a, Zaslavsky et al., 2012]. The MAVEN spacecraft is using the antennas onboard to characterize the dust environment of Mars [Andersson et al., 2014] and Solar Probe Plus will do the same in the inner heliosphere. The challenge, however, is the correct interpretation of the impact signals and calculating the mass of the dust particles. The uncertainties result from the incomplete understanding of the signal pickup mechanisms, and the variation of the signal amplitude with impact location, the ambient plasma environment, and impact speed. A comprehensive laboratory study of impact generated antenna signals has been performed recently using the IMPACT dust accelerator facility operated at the University of Colorado. Dust particles of micron and submicron sizes with velocities of tens of km/s are generated using a 3 MV electrostatic analyzer. A scaled down model spacecraft is exposed to the dust impacts and one or more antennas, connected to sensitive electronics, are used to detect the impact signals. The measurements showed that there are three clearly distinct signal pickup mechanisms due to spacecraft charging, antenna charging and antenna pickup sensing space charge from the expanding plasma cloud. All mechanisms vary with the spacecraft and antenna bias voltages and, furthermore, the latter two

  7. Impact of Air Movement on Eye Symptoms

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Sakoi, Tomonori; Kolencíková, Sona

    2013-01-01

    The impact of direction, oscillation and temperature of isothermal room air movement on eye discomfort and tear film quality was studied. Twenty-four male subjects participated in the experiment. Horizontal air movement against the face and chest was generated by a large desk fan – LDF and a small...... when the airflow was directed against the face and when against the chest, LDF with and without oscillation and PV. Eye tear film samples were taken and analyzed at the beginning and the end of the exposures. Eye irritation and dryness were reported by the subjects. The air movement under individual...... control did not change significantly the tear film quality though tendency for improvement was observed. Eye dryness increased much when the airflow was blowing constantly against the face compared to oscillating airflow, airflow directed against the chest and upward airflow against the face....

  8. Impact of dry eye on work productivity

    OpenAIRE

    Yamada, Masakazu; Mizuno,Yoshinobu; Shigeyasu,Chika

    2012-01-01

    Masakazu Yamada, Yoshinobu Mizuno, Chika ShigeyasuNational Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, JapanBackground: The purpose of this study was to evaluate the impact of dry eye on work productivity of office workers, especially in terms of presenteeism.Methods: A total of 396 individuals aged ≥20 years (258 men and 138 women, mean age 43.4 ± 13.0 years) were recruited through an online survey. Data from 355 responders who d...

  9. Earth Glint Observations Conducted During the Deep Impact Spacecraft Flyby

    Science.gov (United States)

    Barry, R. K.; Deming, L. D.; Robinson, T.; Hewagama, T.

    2010-01-01

    We describe observations of Earth conducted using the High Resolution Instrument (HRI) - a 0.3 m f/35 telescope - on the Deep Impact (DI) spacecraft during its recent flybys. Earth was observed on five occasions: 2008-Mar-18 18:18 UT, 2008-May-28 20:05 UT, 2008-Jun-4 16:57 UT, 2009-Mar-27 16:19 and 2009-Oct-4 09:37 UT. Each set of observations was conducted over a full 24-hour rotation of Earth and a total of thirteen NIR spectra were taken on two-hour intervals during each observing period. Photometry in the 450, SSO, 650 and 8S0 nm filters was taken every fifteen minutes and every hour for the 350, 750 and 950 nm filters. The spacecraft was located over the equator for the three sets of observations in 2008, while the 2009- Mar and 2009-Oct were taken over the north and south Polar Regions, respectively. Observations of calibrator stars Canopus and Achernar were conducted on multiple occasions through all filters. The observations detected a strong specular glint not necessarily associated with a body of water. We describe spectroscopic characterization of the glint and evidence for the possibility of detection of reflection from high cirrus clouds. We describe implications for observations of extrasolar planets.

  10. Meteoroid and technogenic particle impact on spacecraft solar panels

    Science.gov (United States)

    Nadiradze, A. B.; Kalaev, M. P.; Semkin, N. D.

    2016-09-01

    This paper presents calculated models and the results of estimates of meteoroid and technogenic particle impact on spacecraft solar panels. It is shown that optical losses resulting from the formation of microcraters on the surface of protective glasses of semiconductor photoconverters (PC) are negligible (less than 0.01%). Significantly greater losses can occur as a result of shunting the PC p-n junction. In high and medium orbits, these losses are 0.1-0.2%/year for the glass thickness of 150 μm and the area of one PC of 30 cm2. Decreasing the glass thickness up to 100 μm can lead to increasing power losses up to 0.6%/year.

  11. Large Field Photogrammetry Techniques in Aircraft and Spacecraft Impact Testing

    Science.gov (United States)

    Littell, Justin D.

    2010-01-01

    The Landing and Impact Research Facility (LandIR) at NASA Langley Research Center is a 240 ft. high A-frame structure which is used for full-scale crash testing of aircraft and rotorcraft vehicles. Because the LandIR provides a unique capability to introduce impact velocities in the forward and vertical directions, it is also serving as the facility for landing tests on full-scale and sub-scale Orion spacecraft mass simulators. Recently, a three-dimensional photogrammetry system was acquired to assist with the gathering of vehicle flight data before, throughout and after the impact. This data provides the basis for the post-test analysis and data reduction. Experimental setups for pendulum swing tests on vehicles having both forward and vertical velocities can extend to 50 x 50 x 50 foot cubes, while weather, vehicle geometry, and other constraints make each experimental setup unique to each test. This paper will discuss the specific calibration techniques for large fields of views, camera and lens selection, data processing, as well as best practice techniques learned from using the large field of view photogrammetry on a multitude of crash and landing test scenarios unique to the LandIR.

  12. Impact of First Eye versus Second Eye Cataract Surgery on Visual Function and Quality of Life.

    Science.gov (United States)

    Shekhawat, Nakul S; Stock, Michael V; Baze, Elizabeth F; Daly, Mary K; Vollman, David E; Lawrence, Mary G; Chomsky, Amy S

    2017-10-01

    To compare the impact of first eye versus second eye cataract surgery on visual function and quality of life. Cohort study. A total of 328 patients undergoing separate first eye and second eye phacoemulsification cataract surgeries at 5 veterans affairs centers in the United States. Patients with previous ocular surgery, postoperative endophthalmitis, postoperative retinal detachment, reoperation within 30 days, dementia, anxiety disorder, hearing difficulty, or history of drug abuse were excluded. Patients received complete preoperative and postoperative ophthalmic examinations for first eye and second eye cataract surgeries. Best-corrected visual acuity (BCVA) was measured 30 to 90 days preoperatively and postoperatively. Patients completed the National Eye Institute Visual Functioning Questionnaire (NEI-VFQ) 30 to 90 days preoperatively and postoperatively. The NEI-VFQ scores were calculated using a traditional subscale scoring algorithm and a Rasch-refined approach producing visual function and socioemotional subscale scores. Postoperative NEI-VFQ scores and improvement in NEI-VFQ scores comparing first eye versus second eye cataract surgery. Mean age was 70.4 years (±9.6 standard deviation [SD]). Compared with second eyes, first eyes had worse mean preoperative BCVA (0.55 vs. 0.36 logarithm of the minimum angle of resolution (logMAR), P < 0.001), greater mean BCVA improvement after surgery (-0.50 vs. -0.32 logMAR, P < 0.001), and slightly worse postoperative BCVA (0.06 vs. 0.03 logMAR, P = 0.039). Compared with first eye surgery, second eye surgery resulted in higher postoperative NEI-VFQ scores for nearly all traditional subscales (P < 0.001), visual function subscale (-3.85 vs. -2.91 logits, P < 0.001), and socioemotional subscale (-2.63 vs. -2.10 logits, P < 0.001). First eye surgery improved visual function scores more than second eye surgery (-2.99 vs. -2.67 logits, P = 0.021), but both first and second eye surgeries resulted in similar

  13. Triple-root jump in spacecraft potential due to electron beam emission or impact

    International Nuclear Information System (INIS)

    Lai, S.T.

    1992-01-01

    Triple-root jump in spacecraft potential is well understood in the double Maxwellian model of the natural space environment. In this paper, however, the author points out that triple-root jumps in spacecraft potential may also occur during photoemission or electron beam emission from a spacecraft. Impact of an incoming electron beam on a spacecraft may also cause triple-root jumps provided that the beam, ambient plasma, and surface parameters satisfy certain inequality conditions. The parametric conditions under which such beam induced triple-root jumps may occur are presented

  14. A Study of Learning Curve Impact on Three Identical Small Spacecraft

    Science.gov (United States)

    Chen, Guangming; McLennan, Douglas D.

    2003-01-01

    With an eye to the future strategic needs of NASA, the New Millennium Program is funding the Space Technology 5 (ST-5) project to address the future needs in the area of small satellites in constellation missions. The ST-5 project, being developed at Goddard Space Flight Center, involves the development and simultaneous launch of three small, 20-kilogram-class spacecraft. ST-5 is only a test drive and future NASA science missions may call for fleets of spacecraft containing tens of smart and capable satellites in an intelligent constellation. The objective of ST-5 project is to develop three such pioneering small spacecraft for flight validation of several critical new technologies. The ST-5 project team at Goddard Space Flight Center has completed the spacecraft design, is now building and testing the three flight units. The launch readiness date (LRD) is in December 2005. A critical part of ST-5 mission is to prove that it is possible to build these small but capable spacecraft with recurring cost low enough to make future NASA s multi- spacecraft constellation missions viable from a cost standpoint.

  15. Spectacle-related eye injuries, spectacle-impact performance and eye protection.

    Science.gov (United States)

    Hoskin, Annette K; Philip, Swetha; Dain, Stephen J; Mackey, David A

    2015-05-01

    The aim was to review the prevalence of spectacle-related ocular trauma and the performance of currently available spectacle materials and to identify the risk factors associated with spectacle-related ocular trauma. A literature review was conducted using Medline, Embase and Google with the keywords 'eyeglasses' OR 'spectacles' AND 'ocular injury' / 'eye injury'/ 'eye trauma' / 'ocular trauma'. Articles published prior to 1975 were excluded from this review because of advances in spectacle lens technology and Food and Drug Administration legislative changes requiring impact resistance of all prescription spectacle lenses in the United States. Six hundred and ninety-five individual ocular traumas, for which spectacles contributed to or were the main cause of injury, were identified in the literature. Eye injuries occurred when spectacles were worn in sports, in which medium- to high-impact energies were exerted from balls, racquets or bats and/or as a result of a collision with another player. Frame, lens design and product material choice were found to be associated with ocular injury, with polycarbonate lenses cited as the material of choice in the literature. International, regional and national standards for spectacle lenses had a wide range of impact requirements for prescription spectacle lenses, sports eye protection and occupational eye protection. Spectacle-related injury represents a small but preventable cause of ocular injury. With the increasing numbers of spectacle wearers and calls to spend more time outdoors to reduce myopia, spectacle wearers need to be made aware of the potential risks associated with wearing spectacles during medium- to high-risk activities. At particular risk are those prone to falls, the functionally one-eyed, those who have corneal thinning or have had previous eye surgery or injury. With increased understanding of specific risk factors, performance guidelines can be developed for prescription spectacle eye

  16. Low-Impact Space Weather Sensors and the U.S. National Security Spacecraft

    Science.gov (United States)

    2016-09-01

    for deep space missions), also needs to orient its solar arrays toward the sun, none of which can be accomplished without the ability to control the...Spacecraft Thermal Control Handbook: Cryogenics. El Segundo, CA: The Aerospace Press. ESA and NASA. 2015. “ Solar and Heliospheric Observatory Home Page...Distribution is unlimited. 12b. DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) Incorporating inexpensive low-impact targeted surface charging

  17. Singapore Indian Eye Study-2: methodology and impact of migration on systemic and eye outcomes.

    Science.gov (United States)

    Sabanayagam, Charumathi; Yip, Wanfen; Gupta, Preeti; Mohd Abdul, Riswana Bb; Lamoureux, Ecosse; Kumari, Neelam; Cheung, Gemmy Cm; Cheung, Carol Y; Wang, Jie Jin; Cheng, Ching-Yu; Wong, Tien Yin

    2017-11-01

    Asian Indians are the fastest growing migration groups in the world. Studies evaluating the impact of migration on disease outcomes in this population are rare. We describe the methodology of the Singapore Indian Eye Study-2 (SINDI-2) aimed to evaluate the impact of migration status on diabetic retinopathy and other major age-related eye diseases in Asian Indians living in an urban environment. Population-based cohort study. A total of 2200 adults had participated in baseline SINDI (2007-2009, mean age [range] = 57.8 [42.7-84.1] years) and SINDI-2 (2013-2015, 56.5 [48.4-90.2] years). Participants were classified as 'first generation' if they were Indian residents born outside of Singapore and as 'second-generation' immigrants (59.7% in SINDI vs. 63.6% in SINDI-2) if they were born in Singapore. Response rate, participant characteristics and prevalence of systemic diseases were stratified by migration status. Of the 2914 eligible SINDI participants invited to participate, 2200 participated in SINDI-2 (response rate of 75.2%). In both SINDI and SINDI-2, compared with first-generation immigrants, second-generation immigrants were younger, less likely to have income <1000 SGD, had lower levels of pulse pressure, higher levels of high-density lipoprotein cholesterol, had lower prevalence of hypertension and chronic kidney disease and had higher prevalence of current smoking and obesity (all P < 0.05). In both SINDI and SINDI-2, second-generation immigrants had lower prevalence of cardiovascular risk factors except smoking and obesity compared with first-generation immigrants. The final report will confirm if these differences between generations are evident with regard to eye diseases. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

  18. PSS32 Impact of dry eye on everyday life (Ideel) - Symptom bother: Estimating cut-off scores for dry eye severity groups

    OpenAIRE

    Acaster, S.; Verboven, Y.; Begley, C.; Chalmers, R.; Abetz, L.; Thompson, T.

    2011-01-01

    The aims of the study were to estimate score ranges associated with dry eye severity based on the Impact of Dry Eye on Everyday Life (IDEEL) Symptom Bother (SB) domain, and to evaluate the overall performance of the SB domain.

  19. Comparison of eye-safe solid state laser DIAL with passive gas filter correlation measurements from aircraft and spacecraft

    Science.gov (United States)

    Hess, Robert V.; Staton, Leo D.; Wallio, H. Andrew; Wang, Liang-Guo

    1992-01-01

    Differential Absorption Lidar (DIAL) using solid state Ti:sapphire lasers finds current application in the NASA/LASE Project for H2O vapor measurements in the approximately = 0.820 micron region for the lower and mid-troposphere and in potential future applications in planned measurements of the approximately = 0.940 micron region where both strong and weak absorption lines enables measurements throughout the troposphere and lower stratosphere. The challenge exists to perform measurements in the eye-safe greater than 1.5 micron region. A comparison between DIAL and passive Gas Filter Correlation Radiometer (GFCR) measurements is made. The essence of the differences in signal to noise ratio for DIAL and passive GFCR measurements is examined. The state of the art of lasers and optical parametric oscillators (OPO's) is discussed.

  20. A new landing impact attenuation seat in manned spacecraft biologically-inspired by felids

    Directory of Open Access Journals (Sweden)

    Yu Hui

    2015-04-01

    Full Text Available When manned spacecraft comes back to the earth, it relies on the impact attenuation seat to protect astronauts from injuries during landing phase. Hence, the seat needs to transfer impact load, as small as possible, to the crew. However, there is little room left for traditional seat to improve further. Herein, a new seat system biologically-inspired by felids’ landing is proposed. Firstly, a series of experiments was carried out on cats and tigers, in which they were trained to jump down voluntarily from different heights. Based on the ground reaction forces combined with kinematics, the experiment indicated that felids’ landing after self-initial jump was a multi-step impact attenuation process and the new seat was inspired by this. Then the construction and work process of new seat were redesigned to realize the multi-step impact attenuation. The dynamic response of traditional and new seat is analyzed under the identical conditions and the results show that the new concept seat can significantly weaken the occupant overload in two directions compared with that of traditional seat. As a consequence, the risk of injury evaluated for spinal and head is also lowered, meaning a higher level of protection which is especially beneficial to the debilitated astronaut.

  1. Human Response to Ductless Personalised Ventilation: Impact of Air Movement, Temperature and Cleanness on Eye Symptoms

    DEFF Research Database (Denmark)

    Dalewski, Mariusz; Fillon, Maelys; Bivolarova, Maria

    2013-01-01

    environment facially applied individually controlled air movement of room air, with or without local filtering, did not have significant impact on eye blink frequency and tear film quality. The local air movement and air cleaning resulted in increased eye blinking frequency and improvement of tear film......The performance of ductless personalized ventilation (DPV) in conjunction with displacement ventilation (DV) was studied in relation to peoples’ health, comfort and performance. This paper presents results on the impact of room air temperature, using of DPV and local air filtration on eye blink...

  2. Eye Care Quality and Accessibility Improvement in the Community (EQUALITY): impact of an eye health education program on patient knowledge about glaucoma and attitudes about eye care.

    Science.gov (United States)

    Rhodes, Lindsay A; Huisingh, Carrie E; McGwin, Gerald; Mennemeyer, Stephen T; Bregantini, Mary; Patel, Nita; Saaddine, Jinan; Crews, John E; Girkin, Christopher A; Owsley, Cynthia

    2016-01-01

    To assess the impact of the education program of the Eye Care Quality and Accessibility Improvement in the Community (EQUALITY) telemedicine program on at-risk patients' knowledge about glaucoma and attitudes about eye care as well as to assess patient satisfaction with EQUALITY. New or existing patients presenting for a comprehensive eye exam (CEE) at one of two retail-based primary eye clinics were enrolled based on ≥1 of the following at-risk criteria for glaucoma: African Americans ≥40 years of age, Whites ≥50 years of age, diabetes, family history of glaucoma, and/or preexisting diagnosis of glaucoma. A total of 651 patients were enrolled. A questionnaire was administered prior to the patients' CEE and prior to the patients receiving any of the evidence-based eye health education program; a follow-up questionnaire was administered 2-4 weeks later by phone. Baseline and follow-up patient responses regarding knowledge about glaucoma and attitudes about eye care were compared using McNemar's test. Logistic regression models were used to assess the association of patient-level characteristics with improvement in knowledge and attitudes. Overall patient satisfaction was summarized. At follow-up, all patient responses in the knowledge and attitude domains significantly improved from baseline (P≤0.01 for all questions). Those who were unemployed (odds ratio =0.63, 95% confidence interval =0.42-0.95, P=0.026) or had lower education (odds ratio =0.55, 95% confidence interval =0.29-1.02, P=0.058) were less likely to improve their knowledge after adjusting for age, sex, race, and prior glaucoma diagnosis. This association was attenuated after further adjustment for other patient-level characteristics. Ninety-eight percent (n=501) of patients reported being likely to have a CEE within the next 2 years, whereas 63% (n=326) had a CEE in the previous 2 years. Patient satisfaction with EQUALITY was high (99%). Improved knowledge about glaucoma and a high intent to

  3. Impact of eye detection error on face recognition performance

    NARCIS (Netherlands)

    Dutta, A.; Günther, Manuel; El Shafey, Laurent; Veldhuis, Raymond N.J.; Spreeuwers, Lieuwe Jan

    2015-01-01

    The locations of the eyes are the most commonly used features to perform face normalisation (i.e. alignment of facial features), which is an essential preprocessing stage of many face recognition systems. In this study, the authors study the sensitivity of open source implementations of five face

  4. Sensing Passive Eye Response to Impact Induced Head Acceleration Using MEMS IMUs.

    Science.gov (United States)

    Meng, Yuan; Bottenfield, Brent; Bolding, Mark; Liu, Lei; Adams, Mark L

    2018-02-01

    The eye may act as a surrogate for the brain in response to head acceleration during an impact. Passive eye movements in a dynamic system are sensed by microelectromechanical systems (MEMS) inertial measurement units (IMU) in this paper. The technique is validated using a three-dimensional printed scaled human skull model and on human volunteers by performing drop-and-impact experiments with ribbon-style flexible printed circuit board IMUs inserted in the eyes and reference IMUs on the heads. Data are captured by a microcontroller unit and processed using data fusion. Displacements are thus estimated and match the measured parameters. Relative accelerations and displacements of the eye to the head are computed indicating the influence of the concussion causing impacts.

  5. Identifying and assessing strategies for evaluating the impact of mobile eye health units on health outcomes.

    Science.gov (United States)

    Fu, Shiwan; Turner, Angus; Tan, Irene; Muir, Josephine

    2017-12-01

    To identify and assess strategies for evaluating the impact of mobile eye health units on health outcomes. Systematic literature review. Worldwide. Peer-reviewed journal articles that included the use of a mobile eye health unit. Journal articles were included if outcome measures reflected an assessment of the impact of a mobile eye health unit on health outcomes. Six studies were identified with mobile services offering diabetic retinopathy screening (three studies), optometric services (two studies) and orthoptic services (one study). This review identified and assessed strategies in existing literature used to evaluate the impact of mobile eye health units on health outcomes. Studies included in this review used patient outcomes (i.e. disease detection, vision impairment, treatment compliance) and/or service delivery outcomes (i.e. cost per attendance, hospital transport use, inappropriate referrals, time from diabetic retinopathy photography to treatment) to evaluate the impact of mobile eye health units. Limitations include difficulty proving causation of specific outcome measures and the overall shortage of impact evaluation studies. Variation in geographical location, service population and nature of eye care providers limits broad application. © 2017 National Rural Health Alliance Inc.

  6. Case Studies in Crewed Spacecraft Environmental Control and Life Support System Process Compatibility and Cabin Environmental Impact

    Science.gov (United States)

    Perry, J. L.

    2017-01-01

    Contamination of a crewed spacecraft's cabin environment leading to environmental control and life support system (ECLSS) functional capability and operational margin degradation or loss can have an adverse effect on NASA's space exploration mission figures of merit-safety, mission success, effectiveness, and affordability. The role of evaluating the ECLSS's compatibility and cabin environmental impact as a key component of pass trace contaminant control is presented and the technical approach is described in the context of implementing NASA's safety and mission success objectives. Assessment examples are presented for a variety of chemicals used in vehicle systems and experiment hardware for the International Space Station program. The ECLSS compatibility and cabin environmental impact assessment approach, which can be applied to any crewed spacecraft development and operational effort, can provide guidance to crewed spacecraft system and payload developers relative to design criteria assigned ECLSS compatibility and cabin environmental impact ratings can be used by payload and system developers as criteria for ensuring adequate physical and operational containment. In additional to serving as an aid for guiding containment design, the assessments can guide flight rule and procedure development toward protecting the ECLSS as well as approaches for contamination event remediation.

  7. Space Weather Impacts on Spacecraft Operations: Identifying and Establishing High-Priority Operational Services

    Science.gov (United States)

    Lawrence, G.; Reid, S.; Tranquille, C.; Evans, H.

    2013-12-01

    Space Weather is a multi-disciplinary and cross-domain system defined as, 'The physical and phenomenological state of natural space environments. The associated discipline aims, through observation, monitoring, analysis and modelling, at understanding and predicting the state of the Sun, the interplanetary and planetary environments, and the solar and non-solar driven perturbations that affect them, and also at forecasting and nowcasting the potential impacts on biological and technological systems'. National and Agency-level efforts to provide services addressing the myriad problems, such as ESA's SSA programme are therefore typically complex and ambitious undertakings to introduce a comprehensive suite of services aimed at a large number and broad range of end users. We focus on some of the particular threats and risks that Space Weather events pose to the Spacecraft Operations community, and the resulting implications in terms of User Requirements. We describe some of the highest-priority service elements identified as being needed by the Operations community, and outline some service components that are presently available, or under development. The particular threats and risks often vary according to orbit, so the particular User Needs for Operators at LEO, MEO and GEO are elaborated. The inter-relationship between these needed service elements and existing service components within the broader Space Weather domain is explored. Some high-priority service elements and potential correlation with Space Weather drivers include: solar array degradation and energetic proton storms; single event upsets at GEO and solar proton events and galactic cosmic rays; surface charging and deep dielectric charging at MEO and radiation belt dynamics; SEUs at LEO and the South Atlantic Anomaly and its variability. We examine the current capability to provide operational services addressing such threats and identify some advances that the Operations community can expect to benefit

  8. Eye Care Quality and Accessibility Improvement in the Community (EQUALITY: impact of an eye health education program on patient knowledge about glaucoma and attitudes about eye care

    Directory of Open Access Journals (Sweden)

    Rhodes LA

    2016-05-01

    Full Text Available Lindsay A Rhodes,1 Carrie E Huisingh,1 Gerald McGwin Jr,1,2 Stephen T Mennemeyer,3 Mary Bregantini,4 Nita Patel,4 Jinan Saaddine,5 John E Crews,5 Christopher A Girkin,1 Cynthia Owsley11Department of Ophthalmology, School of Medicine, 2Department of Epidemiology, 3Department of Health Care Organization and Policy, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, 4Prevent Blindness, Chicago, IL, USA; 5Vision Health Initiative, Division of Diabetes Translation, Centers for Disease Control and Prevention, Atlanta, GA, USAPurpose: To assess the impact of the education program of the Eye Care Quality and Accessibility Improvement in the Community (EQUALITY telemedicine program on at-risk patients’ knowledge about glaucoma and attitudes about eye care as well as to assess patient satisfaction with EQUALITY.Patients and methods: New or existing patients presenting for a comprehensive eye exam (CEE at one of two retail-based primary eye clinics were enrolled based on ≥1 of the following at-risk criteria for glaucoma: African Americans ≥40 years of age, Whites ≥50 years of age, diabetes, family history of glaucoma, and/or preexisting diagnosis of glaucoma. A total of 651 patients were enrolled. A questionnaire was administered prior to the patients’ CEE and prior to the patients receiving any of the evidence-based eye health education program; a follow-up questionnaire was administered 2–4 weeks later by phone. Baseline and follow-up patient responses regarding knowledge about glaucoma and attitudes about eye care were compared using McNemar’s test. Logistic regression models were used to assess the association of patient-level characteristics with improvement in knowledge and attitudes. Overall patient satisfaction was summarized.Results: At follow-up, all patient responses in the knowledge and attitude domains significantly improved from baseline (P≤0.01 for all questions. Those who were unemployed (odds

  9. Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and micrometeoroids

    International Nuclear Information System (INIS)

    Katayama, Masahide; Takeba, Atsushi; Nitta, Kumi; Kawakita, Shirou; Matsumoto, Haruhisa; Kitazawa, Yukihito

    2010-01-01

    In order to establish the guidelines for the protection of unmanned spacecrafts from the space debris and micrometeoroid impacts, the experimental and numerical investigations have been conducted at Japan Aerospace Exploration Agency. This paper presents mainly its numerical methodology, especially from the viewpoint of highly non-linear and dynamic material model: i.e. the equation of state, constitutive model and fracture or failure model, including a brittle material model for ceramics and an equation of state for the shock-induced vaporization accompanied by hypervelocity impact. The experimental results of hypervelocity impact by two-stage light-gas gun and plasma drag gun are compared with corresponding numerical simulation results by using a hydrocode, and both results are demonstrated to be overall in good agreement with each other.

  10. Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and micrometeoroids

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Masahide, E-mail: masahide.katayama@ctc-g.co.jp [Science and Engineering Systems Division, ITOCHU Techno-Solutions, 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo 100-6080 (Japan); Materials and Structures Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama-shi, Kanagawa 226-8503 (Japan); Takeba, Atsushi [Science and Engineering Systems Division, ITOCHU Techno-Solutions, 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo 100-6080 (Japan); Nitta, Kumi; Kawakita, Shirou; Matsumoto, Haruhisa [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba-city, Ibaraki 305-8505 (Japan); Kitazawa, Yukihito [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba-city, Ibaraki 305-8505 (Japan); Aero-Engine and Space Operations, IHI Corporation, 3-1-1, Toyosu, Koto-ku, Tokyo 135-8710 (Japan)

    2010-10-15

    In order to establish the guidelines for the protection of unmanned spacecrafts from the space debris and micrometeoroid impacts, the experimental and numerical investigations have been conducted at Japan Aerospace Exploration Agency. This paper presents mainly its numerical methodology, especially from the viewpoint of highly non-linear and dynamic material model: i.e. the equation of state, constitutive model and fracture or failure model, including a brittle material model for ceramics and an equation of state for the shock-induced vaporization accompanied by hypervelocity impact. The experimental results of hypervelocity impact by two-stage light-gas gun and plasma drag gun are compared with corresponding numerical simulation results by using a hydrocode, and both results are demonstrated to be overall in good agreement with each other.

  11. Impact of Video Feedback on Teachers' Eye-Contact Mannerisms in Microteaching.

    Science.gov (United States)

    Karasar, Niyazi

    To test the impact of video feedback on teachers' eye-contact mannerisms in microteaching in inservice vocational teacher education, the study utilized video recordings from the data bank generated by previous studies conducted at the Ohio State University's Center for Vocational and Technical Education. The tapes were assigned through a…

  12. The Evolution of Software and Its Impact on Complex System Design in Robotic Spacecraft Embedded Systems

    Science.gov (United States)

    Butler, Roy

    2013-01-01

    The growth in computer hardware performance, coupled with reduced energy requirements, has led to a rapid expansion of the resources available to software systems, driving them towards greater logical abstraction, flexibility, and complexity. This shift in focus from compacting functionality into a limited field towards developing layered, multi-state architectures in a grand field has both driven and been driven by the history of embedded processor design in the robotic spacecraft industry.The combinatorial growth of interprocess conditions is accompanied by benefits (concurrent development, situational autonomy, and evolution of goals) and drawbacks (late integration, non-deterministic interactions, and multifaceted anomalies) in achieving mission success, as illustrated by the case of the Mars Reconnaissance Orbiter. Approaches to optimizing the benefits while mitigating the drawbacks have taken the form of the formalization of requirements, modular design practices, extensive system simulation, and spacecraft data trend analysis. The growth of hardware capability and software complexity can be expected to continue, with future directions including stackable commodity subsystems, computer-generated algorithms, runtime reconfigurable processors, and greater autonomy.

  13. The impact of customer-contractor interactions on spacecraft innovation: Insights from communication satellite history

    Science.gov (United States)

    Szajnfarber, Zoe; Stringfellow, Margaret V.; Weigel, Annalisa L.

    2010-11-01

    This paper captures a first detailed attempt to quantitatively analyze the innovation history of the space sector. Building on a communication satellite innovation metric and a spacecraft innovation framework developed as part of an ongoing project, this paper presents a preliminary model of global communication satellite innovation. In addition to innovation being a function of the rate of performance normalized by price, innovation was found to be strongly influenced by characteristics of the customer-contractor contractual relationship. Specifically, Department of Defense contracts tend to result in a lower level of innovation on average as compared to other customers. Also, particular customer-contractor pairs perform differently and exhibit a second order relationship in time.

  14. Impact of Dry Eye Disease on Work Productivity, and Patients' Satisfaction With Over-the-Counter Dry Eye Treatments.

    Science.gov (United States)

    Nichols, Kelly K; Bacharach, Jason; Holland, Edward; Kislan, Thomas; Shettle, Lee; Lunacsek, Orsolya; Lennert, Barb; Burk, Caroline; Patel, Vaishali

    2016-06-01

    To assess the effect of dry eye disease on work productivity and performance of non-work-related activities, and patients' satisfaction with over-the-counter (OTC) dry eye treatments. In this prospective, noninterventional, cross-sectional study, conducted at 10 U.S. optometry/ophthalmology practices, 158 symptomatic dry eye patients naïve to prescription medication underwent standard dry eye diagnostic tests and completed Work Productivity and Activity Impairment (WPAI) and Ocular Surface Disease Index (OSDI) questionnaires. Use of OTC dry eye medication, and satisfaction with OTC medication and symptom relief were also assessed. On average, dry eye resulted in loss of 0.36% of work time (∼5 minutes over 7 days) and ∼30% impairment of workplace performance (presenteeism), work productivity, and non-job-related activities. Presenteeism and productivity impairment scores showed significant correlation with OSDI total (r = 0.55) and symptom domain (r = 0.50) scores, but not with dry eye clinical signs. Activity impairment score showed stronger correlation with OSDI total (r = 0.61) and symptom domain (r = 0.53) scores than with clinical signs (r ≤ 0.20). Almost 75% of patients used OTC dry eye medication. Levels of patient satisfaction with OTC medication (64.2%) and symptom relief from OTC (37.3%) were unaffected by administration frequency (≥3 vs. ≤2 times daily). Dry eye causes negligible absenteeism, but markedly reduces workplace and non-job-related performances. Impairment of work performance is more closely linked to dry eye symptoms than to clinical signs. Patients' perceptions of OTC dry eye medication tend to be more positive than their perceptions of symptom relief.

  15. Evaluating the risk of eye injuries: intraocular pressure during high speed projectile impacts.

    Science.gov (United States)

    Duma, Stefan M; Bisplinghoff, Jill A; Senge, Danielle M; McNally, Craig; Alphonse, Vanessa D

    2012-01-01

    To evaluate the risk of eye injuries by determining intraocular pressure during high speed projectile impacts. A pneumatic cannon was used to impact eyes with a variety of projectiles at multiple velocities. Intraocular pressure was measured with a small pressure sensor inserted through the optic nerve. A total of 36 tests were performed on 12 porcine eyes with a range of velocities between 6.2 m/s and 66.5 m/s. Projectiles selected for the test series included a 6.35  mm diameter metal ball, a 9.25  mm diameter aluminum rod, and an 11.16  mm diameter aluminum rod. Experiments were designed with velocities in the range of projectile consumer products such as toy guns. A range of intraocular pressures ranged between 2017 mmHg to 26,426 mmHg (39 psi-511 psi). Four of the 36 impacts resulted in globe rupture. Intraocular pressures dramatically above normal physiological pressure were observed for high speed projectile impacts. These pressure data provide critical insight to chronic ocular injuries and long-term complications such as glaucoma and cataracts.

  16. Impact interaction of shells and structural elements of spacecrafts with the particles of space debris and micrometeoroids

    Science.gov (United States)

    Gerasimov, A. V.; Pashkov, S. V.; Khristenko, Yu. F.

    2017-10-01

    Space debris formed during the launch and operation of spacecrafts in the circumterrestrial space, and the flows of micrometeoroids from the depths of space pose a real threat to manned and automatic vehicles. Providing the fracture resistance of aluminum, glass and ceramic spacecraft elements is an important practical task. These materials are widely used in spacecraft elements such as bodies, tanks, windows, glass in optical devices, heat shields, etc.

  17. [Objective assessment of the functional impact of dry eye severity on the quality of vision by double-pass aberrometry].

    Science.gov (United States)

    Habay, T; Majzoub, S; Perrault, O; Rousseau, C; Pisella, P J

    2014-03-01

    To assess the functional impact of the severity of dry eye on the quality of vision by measuring an Objective Scatter Index (OSI) using double pass aberrometry. Twenty-eight patients (56 eyes) with dry eye syndromes of varying severity participated in this study. A double-pass aberrometer was used to measure the dynamic changes in the OSI for 20 seconds. The mean and standard deviations of the OSI and the number of blinks occurring during the examination were compared as a function of the clinical severity of dry eye disease. The mean OSI increased with the severity of dry eye syndrome with a significant difference for stages 3 (P0.8) or visual acuity (P>0.2). Standard deviation of the OSI also increased with the severity of dry eye disease, with a significant difference for stages 3 (P0.2). The values of the OSI standard deviation represented the dynamic nature of aberrometric changes related to the instability of the tear film. Quality of vision of patients deteriorated in relation to the severity of their dry eye. The analysis of OSI standard deviation appears to be an objective way to assess the intensity of subjective visual disturbances reported by patients with dry eye syndrome. It also provides a new tool to assess the severity of damage to the ocular surface. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  18. Impact of dry eye syndrome on vision-related quality of life.

    Science.gov (United States)

    Miljanović, Biljana; Dana, Reza; Sullivan, David A; Schaumberg, Debra A

    2007-03-01

    To evaluate the impact of dry eye syndrome (DES) on vision-associated quality of life. Cross-sectional study. We identified 450 participants in the Women's Health Study (WHS) and 240 participants in the Physicians' Health Study (PHS) and sent a supplementary questionnaire asking how much their everyday activities were limited by symptoms of dry eye and to what degree problems with their eyes limited them in reading, driving, working at the computer, their professional activity, and watching television. By design, one-third of study subjects had clinically diagnosed DES or severe symptoms and two-thirds did not. We used logistic regression to examine relationships of DES with reported problems with everyday activities in each cohort and pooled estimates using meta-analysis methods. Of the participants invited, 85% completed the supplementary questionnaire, including 135 WHS and 55 PHS participants with DES, and 250 WHS and 149 PHS participants without DES. Controlling for age, diabetes, hypertension, and other factors, those with DES were more likely to report problems with reading ([odds ratio] OR = 3.64, 95% [confidence interval] CI 2.45 to 5.40, P computer (OR = 3.37, 95% CI 2.11 to 5.38, P < .0001); watching television (OR = 2.84, 95% CI 1.05 to 7.74, P = .04); driving during the day (OR = 2.80, 95% CI 1.58 to 4.96, P < .0001); and driving at night (OR = 2.20, 95% CI 1.48 to 3.28, P < .0001). DES is associated with a measurable adverse impact on several common and important tasks of daily living, further implicating this condition as an important public health problem deserving increased attention and resources.

  19. Toward a new spacecraft optimal design lifetime? Impact of marginal cost of durability and reduced launch price

    Science.gov (United States)

    Snelgrove, Kailah B.; Saleh, Joseph Homer

    2016-10-01

    The average design lifetime of satellites continues to increase, in part due to the expectation that the satellite cost per operational day decreases monotonically with increased design lifetime. In this work, we challenge this expectation by revisiting the durability choice problem for spacecraft in the face of reduced launch price and under various cost of durability models. We first provide a brief overview of the economic thought on durability and highlight its limitations as they pertain to our problem (e.g., the assumption of zero marginal cost of durability). We then investigate the merging influence of spacecraft cost of durability and launch price, and we identify conditions that give rise cost-optimal design lifetimes that are shorter than the longest lifetime technically achievable. For example, we find that high costs of durability favor short design lifetimes, and that under these conditions the optimal choice is relatively robust to reduction in launch prices. By contrast, lower costs of durability favor longer design lifetimes, and the optimal choice is highly sensitive to reduction in launch price. In both cases, reduction in launch prices translates into reduction of the optimal design lifetime. Our results identify a number of situations for which satellite operators would be better served by spacecraft with shorter design lifetimes. Beyond cost issues and repeat purchases, other implications of long design lifetime include the increased risk of technological slowdown given the lower frequency of purchases and technology refresh, and the increased risk for satellite operators that the spacecraft will be technologically obsolete before the end of its life (with the corollary of loss of value and competitive advantage). We conclude with the recommendation that, should pressure to extend spacecraft design lifetime continue, satellite manufacturers should explore opportunities to lease their spacecraft to operators, or to take a stake in the ownership

  20. Spacecraft operations

    CERN Document Server

    Sellmaier, Florian; Schmidhuber, Michael

    2015-01-01

    The book describes the basic concepts of spaceflight operations, for both, human and unmanned missions. The basic subsystems of a space vehicle are explained in dedicated chapters, the relationship of spacecraft design and the very unique space environment are laid out. Flight dynamics are taught as well as ground segment requirements. Mission operations are divided into preparation including management aspects, execution and planning. Deep space missions and space robotic operations are included as special cases. The book is based on a course held at the German Space Operation Center (GSOC).

  1. Impact of Dry Eye Syndrome on Vision-Related Quality of Life in a Non-Clinic-Based General Population

    Directory of Open Access Journals (Sweden)

    Le Qihua

    2012-07-01

    Full Text Available Abstract Background Dry eye syndrome (DES is a common ocular disorder occurring in general population. The purpose of this study is to evaluate the impact of DES on vision-related quality of life (QoL in a non-clinic-based general population. Methods This population-based cross-sectional study enrolled subjects older than 40 years, who took part in an epidemiological study on dry eye in Sanle Community, Shanghai. Apart from the collection of sociodemographics, dry eye symptoms, and other clinical data, a Chinese version of the 25-item National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25 was administered to all subjects. Comparisons of the NEI VFQ-25 subscale item scores and composite score were made among subgroups divided according to the presence of dry eye symptoms or signs. Multivariate regression analysis was performed to investigate the relationship between the clinical variables and the VFQ-25 composite score. Results A total of 229 participants were enrolled in the study, with an average age of (60.7 ±10.1 years old. Majority of these participants were female (59.8 %, 137/229. The total DES symptom scores (TDSS in subjects either with definite DES or only with dry eye symptoms were significantly higher (F = 60.331, P  Conclusions The symptoms of dry eye are associated with an adverse impact on vision-related QoL in non-clinic-based general population, which is mainly represented as more ocular pain and discomfort, and impaired mental health as well. Apart from clinical examination, it is also important to refer to subjective symptoms and QoL scores when assessing the severity of DES.

  2. Development and validation of the impact of dry eye on everyday life (IDEEL) questionnaire, a patient-reported outcomes (PRO) measure for the assessment of the burden of dry eye on patients.

    Science.gov (United States)

    Abetz, Linda; Rajagopalan, Krithika; Mertzanis, Polyxane; Begley, Carolyn; Barnes, Rod; Chalmers, Robin

    2011-12-08

    To develop and validate a comprehensive patient-reported outcomes instrument focusing on the impact of dry eye on everyday life (IDEEL). Development and validation of the IDEEL occurred in four phases: 1) focus groups with 45 dry eye patients to develop a draft instrument, 2) item generation, 3) pilot study to assess content validity in 16 patients and 4) psychometric validation in 210 subjects: 130 with non-Sjögren's keratoconjunctivitis sicca, 32 with Sjögren's syndrome and 48 controls, and subsequent item reduction. Focus groups identified symptoms and the associated bother, the impact of dry eye on daily life and the patients' satisfaction with their treatment as the central concepts in patients' experience of dry eye. Qualitative analysis indicated that saturation was achieved for these concepts and yielded an initial 112-item draft instrument. Patients understood the questionnaire and found the items to be relevant indicating content validity. Patient input, item descriptive statistics and factor analysis identified 55 items that could be deleted. The final 57-item IDEEL assesses dry eye impact constituting 3 modules: dry eye symptom-bother, dry eye impact on daily life comprising impact on daily activities, emotional impact, impact on work, and dry eye treatment satisfaction comprising satisfaction with treatment effectiveness and treatment-related bother/inconvenience. The psychometric analysis results indicated that the IDEEL met the criteria for item discriminant validity, internal consistency reliability, test-retest reliability and floor/ceiling effects. As expected, the correlations between IDEEL and the Dry Eye Questionnaire (a habitual symptom questionnaire) were higher than between IDEEL and Short-Form-36 and EuroQoL-5D, indicating concurrent validity. The IDEEL is a reliable, valid and comprehensive questionnaire relevant to issues that are specific to dry eye patients, and meets current FDA patient-reported outcomes guidelines. The use of this

  3. Dry Eye

    Science.gov (United States)

    ... Eye » Facts About Dry Eye Listen Facts About Dry Eye Fact Sheet Blurb The National Eye Institute (NEI) ... and their families search for general information about dry eye. An eye care professional who has examined the ...

  4. Impact of lifestyle intervention on dry eye disease in office workers: a randomized controlled trial.

    Science.gov (United States)

    Kawashima, Motoko; Sano, Kokoro; Takechi, Sayuri; Tsubota, Kazuo

    2018-04-04

    To evaluate the effects of a 2-month lifestyle intervention for dry eye disease in office workers. Prospective interventional study (randomized controlled study). Forty-one middle-aged Japanese office workers (men, 22; women, 19; 39.2 ± 8.0 years) with definite and probable dry eye disease were enrolled and randomized to an intervention group (n = 22) and a control group (n = 19). The intervention aimed at modifying diet, increasing physical activity, and encouraging positive thinking. The primary outcome was change in dry eye disease diagnoses. Secondary outcome was change in disease parameters, including dry eye symptoms, as assessed using the Dry Eye-Related Quality of Life Score, corneal and conjunctival staining scores, tear break-up time, and Schirmer test results. A total of 36 participants (intervention group, 17; control group, 19) completed the study. The number of definite dry eye disease diagnoses decreased from four to none (p =.05), and the dry eye symptom score showed a significant decrease in the intervention group (p =.03). In contrast, the corneal and conjunctival staining scores, tear break-up time, and Schirmer test results did not differ significantly between groups. The 2-month lifestyle intervention employed in this study improved dry eye disease status among office workers, with a considerable decrease in subjective symptoms. Lifestyle intervention may be a promising management option for dry eye disease, although further investigation of long-term effects are required.

  5. Simulation of airbag impact on eyes with different axial lengths after transsclerally fixated posterior chamber intraocular lens by using finite element analysis

    Directory of Open Access Journals (Sweden)

    Huang J

    2015-02-01

    Full Text Available Jane Huang,1 Eiichi Uchio,1 Satoru Goto2 1Department of Ophthalmology, Fukuoka University School of Medicine, Fukuoka, 2Nihon ESI KK Technical Division, Tokyo, Japan Purpose: To determine the biomechanical response of an impacting airbag on eyes with different axial lengths with transsclerally fixated posterior chamber intraocular lens (PC IOL.Materials and methods: Simulations in a model human eye were performed with a computer using a finite element analysis program created by Nihon, ESI Group. The airbag was set to be deployed at five different velocities and to impact on eyes with three different axial lengths. These eyes were set to have transsclerally fixated PC IOL by a 10-0 polypropylene possessing a tensile force limit of 0.16 N according to the United States Pharmacopeia XXII.Results: The corneoscleral opening was observed at a speed of 40 m/second or more in all model eyes. Eyes with the longest axial length of 25.85 mm had the greatest extent of deformity at any given impact velocity. The impact force exceeded the tensile force of 10-0 polypropylene at an impact velocity of 60 m/second in all eyes, causing breakage of the suture. Conclusion: Eyes with transsclerally fixated PC IOL could rupture from airbag impact at high velocities. Eyes with long axial lengths experienced a greater deformity upon airbag impact due to a thinner eye wall. Further basic research on the biomechanical response for assessing eye injuries could help in developing a better airbag and in the further understanding of ocular traumas. Keywords: airbag, ocular trauma, computer simulation, transsclerally fixated posterior chamber intraocular lens, finite element analysis

  6. Impact of radiation protection means on the dose to the lens of the eye while handling radionuclides in nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Bruchmann, Iris; Szermerski, Bastian; Geworski, Lilli [Medical School Hannover (Germany). Dept. for Radiation Protection and Medical Physics; Behrens, Rolf [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany)

    2016-07-01

    The human eye lens appears to be more radiosensitive than previously assumed. The reduction of the limit for the dose to the lens of the eye to 20 mSv per year has been passed in the current Euratom Directives (2013). Therefore, in this work the impact of laboratory glasses and X-ray protective goggles was investigated and reciprocal attenuation factors (i.e. transmission factors) for different nuclides (Tc-99m, I-131, Y-90, F-18 and Ga-68) were determined. The radionuclides in typical geometry (syringe, applicator) were positioned at a distance of 50 cm to the eyes of four Alderson-Head-Phantoms. Different dosemeters measuring H{sub p}(3) respective H{sub p}(0.07) were fixed to the eyes of the phantoms, either behind the glasses or without any protection means, respectively. The mean reciprocal attenuation factors were determined to be between unity for F-18 and I-131 using laboratory glasses (no attenuation effect) and < 0.01 for Y-90 using X-ray protective goggles. All other results were between these extremes. It has been shown, that prospective doses to the lens of the eye can be reduced significantly by using appropriate radiation protection means, especially for those dose-relevant beta radiation emitting nuclides such as Y-90.

  7. Impact of Glaucoma and Dry Eye on Text-Based Searching

    Science.gov (United States)

    Sun, Michelle J.; Rubin, Gary S.; Akpek, Esen K.; Ramulu, Pradeep Y.

    2017-01-01

    Purpose We determine if visual field loss from glaucoma and/or measures of dry eye severity are associated with difficulty searching, as judged by slower search times on a text-based search task. Methods Glaucoma patients with bilateral visual field (VF) loss, patients with clinically significant dry eye, and normally-sighted controls were enrolled from the Wilmer Eye Institute clinics. Subjects searched three Yellow Pages excerpts for a specific phone number, and search time was recorded. Results A total of 50 glaucoma subjects, 40 dry eye subjects, and 45 controls completed study procedures. On average, glaucoma patients exhibited 57% longer search times compared to controls (95% confidence interval [CI], 26%–96%, P Dry eye subjects demonstrated similar search times compared to controls, though worse Ocular Surface Disease Index (OSDI) vision-related subscores were associated with longer search times (P dry eye (P > 0.08 for Schirmer's testing without anesthesia, corneal fluorescein staining, and tear film breakup time). Conclusions Text-based visual search is slower for glaucoma patients with greater levels of VF loss and dry eye patients with greater self-reported visual difficulty, and these difficulties may contribute to decreased quality of life in these groups. Translational Relevance Visual search is impaired in glaucoma and dry eye groups compared to controls, highlighting the need for compensatory strategies and tools to assist individuals in overcoming their deficiencies. PMID:28670502

  8. Potential public health impact of Age-Related Eye Disease Study results: AREDS report no. 11.

    Science.gov (United States)

    Bressler, Neil M; Bressler, Susan B; Congdon, Nathan G; Ferris, Frederick L; Friedman, David S; Klein, Ronald; Lindblad, Anne S; Milton, Roy C; Seddon, Johanna M

    2003-11-01

    To estimate the potential public health impact of the findings of the Age-Related Eye Disease Study (AREDS) on reducing the number of persons developing advanced age-related macular degeneration (AMD) during the next 5 years in the United States. The AREDS clinical trial provides estimates of AMD progression rates and of reduction in risk of developing advanced AMD when a high-dose nutritional supplement of antioxidants and zinc is used. These results are applied to estimates of the US population at risk, to estimate the number of people who would potentially avoid advanced AMD during 5 years if those at risk were to take a supplement such as that used in AREDS. An estimated 8 million persons at least 55 years old in the United States have monocular or binocular intermediate AMD or monocular advanced AMD. They are considered to be at high risk for advanced AMD and are those for whom the AREDS formulation should be considered. Of these people, 1.3 million would develop advanced AMD if no treatment were given to reduce their risk. If all of these people at risk received supplements such as those used in AREDS, more than 300,000 (95% confidence interval, 158,000-487,000) of them would avoid advanced AMD and any associated vision loss during the next 5 years. If people at high risk for advanced AMD received supplements such as those suggested by AREDS results, the potential impact on public health in the United States would be considerable during the next 5 years.

  9. Impact of visors on eye and orbital injuries in the National Hockey League.

    Science.gov (United States)

    Micieli, Jonathan A; Zurakowski, David; Ahmed, Iqbal Ike K

    2014-06-01

    Eye and orbital injuries are a significant risk to professional hockey league players and have resulted in career-ending injuries. The goal of this study was to determine the incidence, value lost, mechanism, and effect of visors on eye and orbital injuries over the last 10 National Hockey League (NHL) seasons: 2002-2003 to 2012-2013. Retrospective case-control study. Participants were 8741 NHL players who had played at least 1 game during the last 10 seasons. Using The Sports Network (TSN), ProSportsTransactions, and the Sporting News Hockey Register, NHL players were searched to identify eye and orbital injuries. The mechanism of injury was obtained from media reports and direct observation from online videos. The number of players wearing visors each year was obtained from The Hockey News annual visor survey. A total of 149 eye or orbital injuries over the last 10 seasons resulted in an overall incidence of 2.48 per 10 000 athlete exposures. A total of 1120 missed games led to a lost financial value of more than $33 million. Visor use among players grew from 32% in 2002-2003 to 73% in 2012-2013, and there was a significantly increased risk for having an eye or orbital injury when a visor was not worn (OR 4.23, 95% CI 2.84-6.30). Most injuries were a result of being hit by a deflected or direct puck (37%) followed by being struck by a high stick (28%). Players who did not wear a visor were found to be involved in more fights, hits, and penalty minutes (p < 0.001). Eye and orbital injuries are mostly accidental in nature and represent a significant risk and cost to the NHL and its players. Eye and orbital injuries are significantly more likely in players who do not wear visors. Copyright © 2014 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  10. Spacecraft radiator systems

    Science.gov (United States)

    Anderson, Grant A. (Inventor)

    2012-01-01

    A spacecraft radiator system designed to provide structural support to the spacecraft. Structural support is provided by the geometric "crescent" form of the panels of the spacecraft radiator. This integration of radiator and structural support provides spacecraft with a semi-monocoque design.

  11. Eye Allergies

    Science.gov (United States)

    ... Español Eye Health / Eye Health A-Z Eye Allergies Sections What Are Eye Allergies? Eye Allergy Symptoms ... allergy diagnosis Eye allergy treatment What Are Eye Allergies? Leer en Español: ¿Qué son las alergias de ...

  12. Impact of Spatial Resolution on Wind Field Derived Estimates of Air Pressure Depression in the Hurricane Eye

    Directory of Open Access Journals (Sweden)

    Linwood Jones

    2010-03-01

    Full Text Available Measurements of the near surface horizontal wind field in a hurricane with spatial resolution of order 1–10 km are possible using airborne microwave radiometer imagers. An assessment is made of the information content of the measured winds as a function of the spatial resolution of the imager. An existing algorithm is used which estimates the maximum surface air pressure depression in the hurricane eye from the maximum wind speed. High resolution numerical model wind fields from Hurricane Frances 2004 are convolved with various HIRAD antenna spatial filters to observe the impact of the antenna design on the central pressure depression in the eye that can be deduced from it.

  13. Airborne particulate matter in spacecraft

    Science.gov (United States)

    1988-01-01

    Acceptability limits and sampling and monitoring strategies for airborne particles in spacecraft were considered. Based on instances of eye and respiratory tract irritation reported by Shuttle flight crews, the following acceptability limits for airborne particles were recommended: for flights of 1 week or less duration (1 mg/cu m for particles less than 10 microns in aerodynamic diameter (AD) plus 1 mg/cu m for particles 10 to 100 microns in AD); and for flights greater than 1 week and up to 6 months in duration (0.2 mg/cu m for particles less than 10 microns in AD plus 0.2 mg/cu m for particles 10 to 100 microns in AD. These numerical limits were recommended to aid in spacecraft atmosphere design which should aim at particulate levels that are a low as reasonably achievable. Sampling of spacecraft atmospheres for particles should include size-fractionated samples of 0 to 10, 10 to 100, and greater than 100 micron particles for mass concentration measurement and elementary chemical analysis by nondestructive analysis techniques. Morphological and chemical analyses of single particles should also be made to aid in identifying airborne particulate sources. Air cleaning systems based on inertial collection principles and fine particle collection devices based on electrostatic precipitation and filtration should be considered for incorporation into spacecraft air circulation systems. It was also recommended that research be carried out in space in the areas of health effects and particle characterization.

  14. IMPACT OF PHYSICIAN COMMUNICATION ON DIABETIC EYE EXAMINATION ADHERENCE: Results From a Retrospective Cohort Analysis.

    Science.gov (United States)

    Storey, Philip P; Murchison, Ann P; Pizzi, Laura T; Hark, Lisa A; Dai, Yang; Leiby, Benjamin E; Haller, Julia A

    2016-01-01

    To evaluate the effect of written communication between an ophthalmologist and a primary care physician (PCP) on patient adherence to diabetic eye examination recommendations. In a retrospective cohort study of a multiethnic population at an urban ophthalmology center, records of all patients with diabetes and clinic visits between 2007 and 2010 were reviewed. Data collected included patient demographics, insurance status, hemoglobin A1C, severity of diabetic retinopathy, follow-up examinations, and written communication between a patient's ophthalmologist and PCP. Statistical analyses were performed to examine the relationship between physician communication and adherence to diabetic eye examination based on the American Academy of Ophthalmology-published recommendations. A total of 1,968 people with diabetes were included. Written communication from an ophthalmologist to a PCP was associated with increased adherence to follow-up eye examination recommendations (Odds Ratio: 1.49; 95% Confidence Interval: 1.16-1.92; P = 0.0018). Communication from a PCP to an ophthalmologist was also associated with increased adherence (Odds Ratio: 1.94; 95% Confidence Interval: 1.37-2.77; P = 0.0002). Multivariable analysis controlling for other factors associated with examination adherence confirmed that communication both to and from an ophthalmologist was independently and significantly associated with increased follow-up adherence. Patients with communication between ophthalmologists and PCPs are more likely to adhere to diabetic eye examinations.

  15. Impact of oral vitamin D supplementation on the ocular surface in people with dry eye and/or low serum vitamin D.

    Science.gov (United States)

    Yang, Chih-Huang; Albietz, Julie; Harkin, Damien G; Kimlin, Michael G; Schmid, Katrina L

    2018-02-01

    To determine the possible association between serum vitamin D levels and dry eye symptoms, and the impact of an oral vitamin D supplement. Three linked studies were performed. (i) 29 older adult participants, (ii) 29 dry eyed participants, and (iii) 2-month vitamin D supplementation for 32 dry eyed/low serum vitamin D levelled participants. All participants were assessed by the Ocular Surface Diseases Index (OSDI) to determine dry eye symptoms, and the phenol red thread test (PRT) and/or Schirmer's tear test, tear meniscus height, non-invasive tear break up time, grading ocular surface redness and fluorescein staining of the cornea to detect the tear quality and ocular surface conditions. Blood samples were collected for serum vitamin D analysis and interleukin-6 (IL-6) levels. Among older adult participants, vitamin D levels were negatively correlated with dry eye symptoms, the severity of dry eye, and associated with tired eye symptom. Vitamin D levels of people with dry eye diagnosis were not correlated with OSDI scores and IL-6 levels; while IL-6 levels showed correlation with tear production. In supplement study, vitamin D levels increased by 29mol/l, while dry eye symptoms and grading of corneal staining appeared significant reductions. No significant changes in IL-6 levels. Low vitamin D levels (dry eye symptoms in older individuals but not those diagnosed with dry eye. Vitamin D supplement increased the vitamin D levels, and improved dry eye symptoms, the tear quality and ocular surface conditions. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  16. When is protection from impact needed for the face as well as the eyes in occupational environments?

    Science.gov (United States)

    Dain, Stephen J; Huang, Rose; Tiao, Aimee; Chou, B Ralph

    2018-05-01

    The most commonly identified reason for requiring or using occupational eye and face protection is for protection against flying objects. Standards vary on what risk may require protection of the eyes alone and what requires protection for the whole face. Information on the minimum energy transfer for face damage to occur is not well-established. The heads of pigs were used as the common model for human skin. A 6 mm steel ball projected at velocities between 45 and 135 m/s was directed at the face area. Examples of impacts were filmed with a high-speed camera and the resulting damage was rated visually on a scale from 1 (no visible damage) to 5 (penetrated the skin and embedded in the flesh). The results for the cheek area indicate that 85 m/s is the velocity above which damage is more likely to occur unless the skin near the lip is included. For damage to the lip area to be avoided, the velocity needs to be 60 m/s or less. The present data support a maximum impact velocity of 85 m/s, provided the thinner and more vulnerable skin of the lids and orbital adnexa is protected. If the coverage area does not extend to the orbital adnexa, then the absolute upper limit for the velocity is 60 m/s. At this stage, eye-only protection, as represented by the lowest level of impact test in the standards in the form of a drop ball test, is not in question. © 2017 Optometry Australia.

  17. Connecting eye to eye

    DEFF Research Database (Denmark)

    Dau, Susanne; Rask, Anders Bindslev

    2017-01-01

    Computer Supported Collaborative Learning (CSCL) is used a frame for supporting online and blended learning in educations. The online communication and collaboration are afforded by the social collaboration. However, the social collaboration is based on the establishment of direct eye contact...... (Khalid, Deska & Hugenberg, 2016), but direct eye contact is challenged by the position of the digital devices and thus CSCL. Lack of eye contact is the chief contributor to the negative effects of online disinhibition (Lapidot-Lefler & Barak, 2012) and the problem is the location of the web camera...... at the computer. Eye contact is challenged by the displacement between the senders´ and receivers´ focus on the screen picture and the camera's location at the top or bottom of screens on all digital devices. The aim of this paper is accordingly to investigate the influence of the displacement in eye contact...

  18. Eyes Wide Open

    Directory of Open Access Journals (Sweden)

    Zoi Manesi

    2016-04-01

    Full Text Available Research from evolutionary psychology suggests that the mere presence of eye images can promote prosocial behavior. However, the “eye images effect” is a source of considerable debate, and findings across studies have yielded somewhat inconsistent support. We suggest that one critical factor may be whether the eyes really need to be watching to effectively enhance prosocial behavior. In three experiments, we investigated the impact of eye images on prosocial behavior, assessed in a laboratory setting. Participants were randomly assigned to view an image of watching eyes (eyes with direct gaze, an image of nonwatching eyes (i.e., eyes closed for Study 1 and averted eyes for Studies 2 and 3, or an image of flowers (control condition. Upon exposure to the stimuli, participants decided whether or not to help another participant by completing a dull cognitive task. Three independent studies produced somewhat mixed results. However, combined analysis of all three studies, with a total of 612 participants, showed that the watching component of the eyes is important for decision-making in this context. Images of watching eyes led to significantly greater inclination to offer help as compared to images of nonwatching eyes (i.e., eyes closed and averted eyes or images of flowers. These findings suggest that eyes gazing at an individual, rather than any proxy to social presence (e.g., just the eyes, serve as a reminder of reputation. Taken together, we conclude that it is “eyes that pay attention” that can lift the veil of anonymity and potentially facilitate prosocial behavior.

  19. Computer simulation of spacecraft/environment interaction

    International Nuclear Information System (INIS)

    Krupnikov, K.K.; Makletsov, A.A.; Mileev, V.N.; Novikov, L.S.; Sinolits, V.V.

    1999-01-01

    This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language

  20. Computer simulation of spacecraft/environment interaction

    CERN Document Server

    Krupnikov, K K; Mileev, V N; Novikov, L S; Sinolits, V V

    1999-01-01

    This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language.

  1. EYE TRACKING TO EXPLORE THE IMPACTS OF PHOTOREALISTIC 3D REPRESENTATIONS IN PEDSTRIAN NAVIGATION PERFORMANCE

    Directory of Open Access Journals (Sweden)

    W. Dong

    2016-06-01

    Full Text Available Despite the now-ubiquitous two-dimensional (2D maps, photorealistic three-dimensional (3D representations of cities (e.g., Google Earth have gained much attention by scientists and public users as another option. However, there is no consistent evidence on the influences of 3D photorealism on pedestrian navigation. Whether 3D photorealism can communicate cartographic information for navigation with higher effectiveness and efficiency and lower cognitive workload compared to the traditional symbolic 2D maps remains unknown. This study aims to explore whether the photorealistic 3D representation can facilitate processes of map reading and navigation in digital environments using a lab-based eye tracking approach. Here we show the differences of symbolic 2D maps versus photorealistic 3D representations depending on users’ eye-movement and navigation behaviour data. We found that the participants using the 3D representation were less effective, less efficient and were required higher cognitive workload than using the 2D map for map reading. However, participants using the 3D representation performed more efficiently in self-localization and orientation at the complex decision points. The empirical results can be helpful to improve the usability of pedestrian navigation maps in future designs.

  2. Visual impact assessment: there's more to it than meets the eye

    International Nuclear Information System (INIS)

    Robotham, A.J.; Quilleash, P.

    1992-01-01

    The visual impact of a wind farm is one of the major causes of concern for all current U.K. wind farm projects. Often visual impact is the singlemost important issue on which a planning application is judged. A fair and honest assessment of the visual impact of a wind farm demands the co-operation of the developer, the planning authority, the public, and other interested parties. Visual impact assessment also demands that each individual involved in the planning process make their own judgement, because it is inadequate for this issue to be decided by a single individual. (author)

  3. Spacecraft Spin Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides the capability to correct unbalances of spacecraft by using dynamic measurement techniques and static/coupled measurements to provide products of...

  4. Corneal and conjunctival drug permeability: Systematic comparison and pharmacokinetic impact in the eye.

    Science.gov (United States)

    Ramsay, Eva; Del Amo, Eva M; Toropainen, Elisa; Tengvall-Unadike, Unni; Ranta, Veli-Pekka; Urtti, Arto; Ruponen, Marika

    2018-07-01

    On the surface of the eye, both the cornea and conjunctiva are restricting ocular absorption of topically applied drugs, but barrier contributions of these two membranes have not been systemically compared. Herein, we studied permeability of 32 small molecular drug compounds across an isolated porcine cornea and built a quantitative structure-property relationship (QSPR) model for the permeability. Corneal drug permeability (data obtained for 25 drug molecules) showed a 52-fold range in permeability (0.09-4.70 × 10 -6  cm/s) and the most important molecular descriptors in predicting the permeability were hydrogen bond donor, polar surface area and halogen ratio. Corneal permeability values were compared to their conjunctival drug permeability values. Ocular drug bioavailability and systemic absorption via conjunctiva were predicted for this drug set with pharmacokinetic calculations. Drug bioavailability in the aqueous humour was simulated to be drug across the conjunctiva to the blood circulation restricts significantly ocular drug bioavailability and, therefore, ocular absorption does not increase proportionally with the increasing corneal drug permeability. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Eye Protection

    OpenAIRE

    Pashby, Tom

    1986-01-01

    Eye injuries frequently occur in the home, at work and at play. Many result in legally blind eyes, and most are preventable. Awareness of potential hazards is essential to preventing eye injuries, particularly in children. In addition, protective devices must be used appropriately. We have developed eye protectors that have proved effective in reducing both the overall incidence and the severity of sports eye injuries.

  6. Disease impact in chronic progressive external ophthalmoplegia: more than meets the eye

    NARCIS (Netherlands)

    Smits, B.W.; Fermont, J.; Delnooz, C.C.S.; Kalkman, J.S.; Bleijenberg, G.; Engelen, B.G.M. van

    2011-01-01

    We determined the extent of disease impact in 28 patients with genetically confirmed chronic progressive external ophthalmoplegia (CPEO) and compared the outcomes to those of matched myotonic dystrophy type I patients. CPEO patients reported a high frequency of severe fatigue (67.9%), pain (96.2%),

  7. Spacecraft Charge Monitor

    Science.gov (United States)

    Goembel, L.

    2003-12-01

    We are currently developing a flight prototype Spacecraft Charge Monitor (SCM) with support from NASA's Small Business Innovation Research (SBIR) program. The device will use a recently proposed high energy-resolution electron spectroscopic technique to determine spacecraft floating potential. The inspiration for the technique came from data collected by the Atmosphere Explorer (AE) satellites in the 1970s. The data available from the AE satellites indicate that the SCM may be able to determine spacecraft floating potential to within 0.1 V under certain conditions. Such accurate measurement of spacecraft charge could be used to correct biases in space plasma measurements. The device may also be able to measure spacecraft floating potential in the solar wind and in orbit around other planets.

  8. Quantifying climate change impacts emphasises the importance of managing regional threats in the endangered Yellow-eyed penguin

    Directory of Open Access Journals (Sweden)

    Thomas Mattern

    2017-05-01

    Full Text Available Climate change is a global issue with effects that are difficult to manage at a regional scale. Yet more often than not climate factors are just some of multiple stressors affecting species on a population level. Non-climatic factors—especially those of anthropogenic origins—may play equally important roles with regard to impacts on species and are often more feasible to address. Here we assess the influence of climate change on population trends of the endangered Yellow-eyed penguin (Megadyptes antipodes over the last 30 years, using a Bayesian model. Sea surface temperature (SST proved to be the dominating factor influencing survival of both adult birds and fledglings. Increasing SST since the mid-1990s was accompanied by a reduction in survival rates and population decline. The population model showed that 33% of the variation in population numbers could be explained by SST alone, significantly increasing pressure on the penguin population. Consequently, the population becomes less resilient to non-climate related impacts, such as fisheries interactions, habitat degradation and human disturbance. However, the extent of the contribution of these factors to declining population trends is extremely difficult to assess principally due to the absence of quantifiable data, creating a discussion bias towards climate variables, and effectively distracting from non-climate factors that can be managed on a regional scale to ensure the viability of the population.

  9. Impact of plant cover on fitness and behavioural traits of captive red-eyed tree frogs (Agalychnis callidryas.

    Directory of Open Access Journals (Sweden)

    Christopher J Michaels

    Full Text Available Despite the importance of ex situ conservation programmes as highlighted in the Amphibian Conservation Action Plan, there are few empirical studies that examine the influence of captive conditions on the fitness of amphibians, even for basic components of enclosure design such as cover provision. Maintaining the fitness of captive amphibian populations is essential to the success of ex situ conservation projects. Here we examined the impact of plant cover on measures of fitness and behaviour in captive red-eyed tree frogs (Agalychnis callidryas. We found significant effects of plant provision on body size, growth rates and cutaneous bacterial communities that together demonstrate a compelling fitness benefit from cover provision. We also demonstrate a strong behavioural preference for planted rather than non-planted areas. We also assessed the impact of plant provision on the abiotic environment in the enclosure as a potential driver of these behavioural and fitness effects. Together this data provides valuable information regarding enclosure design for a non-model amphibian species and has implications for amphibian populations maintained in captivity for conservation breeding programmes and research.

  10. Impacts of dust aerosol and adjacency effects on the accuracy of Landsat 8 and RapidEye surface reflectances

    KAUST Repository

    Houborg, Rasmus; McCabe, Matthew

    2017-01-01

    The atmospheric correction of satellite data is challenging over desert agricultural systems, due to the relatively high aerosol optical thicknesses (τ550), bright soils, and a heterogeneous surface reflectance field. Indeed, the contribution of reflected radiation from adjacent pixels scattered into the field of view of a target pixel is considerable and can significantly affect the fidelity of retrieved reflectances. In this study, uncertainties and quantitative errors associated with the atmospheric correction of multi-spectral Landsat 8 and RapidEye data were characterized over a desert agricultural landscape in Saudi Arabia. Surface reflectances were retrieved using an implementation of the 6SV atmospheric correction code, and validated against field collected spectroradiometer measurements over desert, cultivated soil, and vegetated surface targets. A combination of satellite and Aerosol Robotic Network (AERONET) data were used to parameterize aerosol properties and atmospheric state parameters. With optimal specification of τ550 and aerosol optical properties and correction for adjacency effects, the relative Mean Absolute Deviation (MAD) for all bands combined was 5.4% for RapidEye and 6.8% for Landsat 8. However uncertainties associated with satellite-based τ550 retrievals were shown to introduce significant error into the reflectance estimates. With respect to deriving common vegetation indices from corrected reflectance data, the Normalized Difference Vegetation Index (NDVI) was associated with the smallest errors (3–8% MAD). Surface reflectance errors were highest for bands in the visible part of the spectrum, particularly the blue band (5–16%), while there was more consistency within the red-edge (~ 5%) and near-infrared (5–7%). Results were generally better constrained when a τ550-dependent aerosol model for desert dust particles, parameterized on the basis of nearby AERONET site data, was used in place of a generic rural or background

  11. Impacts of dust aerosol and adjacency effects on the accuracy of Landsat 8 and RapidEye surface reflectances

    KAUST Repository

    Houborg, Rasmus

    2017-03-29

    The atmospheric correction of satellite data is challenging over desert agricultural systems, due to the relatively high aerosol optical thicknesses (τ550), bright soils, and a heterogeneous surface reflectance field. Indeed, the contribution of reflected radiation from adjacent pixels scattered into the field of view of a target pixel is considerable and can significantly affect the fidelity of retrieved reflectances. In this study, uncertainties and quantitative errors associated with the atmospheric correction of multi-spectral Landsat 8 and RapidEye data were characterized over a desert agricultural landscape in Saudi Arabia. Surface reflectances were retrieved using an implementation of the 6SV atmospheric correction code, and validated against field collected spectroradiometer measurements over desert, cultivated soil, and vegetated surface targets. A combination of satellite and Aerosol Robotic Network (AERONET) data were used to parameterize aerosol properties and atmospheric state parameters. With optimal specification of τ550 and aerosol optical properties and correction for adjacency effects, the relative Mean Absolute Deviation (MAD) for all bands combined was 5.4% for RapidEye and 6.8% for Landsat 8. However uncertainties associated with satellite-based τ550 retrievals were shown to introduce significant error into the reflectance estimates. With respect to deriving common vegetation indices from corrected reflectance data, the Normalized Difference Vegetation Index (NDVI) was associated with the smallest errors (3–8% MAD). Surface reflectance errors were highest for bands in the visible part of the spectrum, particularly the blue band (5–16%), while there was more consistency within the red-edge (~ 5%) and near-infrared (5–7%). Results were generally better constrained when a τ550-dependent aerosol model for desert dust particles, parameterized on the basis of nearby AERONET site data, was used in place of a generic rural or background

  12. Eye Cancer

    Science.gov (United States)

    Cancer of the eye is uncommon. It can affect the outer parts of the eye, such as the eyelid, which are made up ... and nerves. If the cancer starts inside the eyeball it's called intraocular cancer. The most common intraocular ...

  13. Black Eye

    Science.gov (United States)

    ... Your Eyes Sep 20, 2017 Eye Injuries from Laundry Packets On the Rise Jun 30, 2017 ... Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American ...

  14. Eye Anatomy

    Science.gov (United States)

    ... News About Us Donate In This Section Eye Anatomy en Español email Send this article to a ... You at Risk For Glaucoma? Childhood Glaucoma Eye Anatomy Five Common Glaucoma Tests Glaucoma Facts and Stats ...

  15. Eye Emergencies

    Science.gov (United States)

    ... The Marfan Foundation Marfan & Related Disorders What is Marfan Syndrome? What are Related Disorders? What are the Signs? ... Emergencies Eye Emergencies Lung Emergencies Surgeries Eye Emergencies Marfan syndrome significantly increases your risk of retinal detachment, a ...

  16. Fractionated Spacecraft Architectures Seeding Study

    National Research Council Canada - National Science Library

    Mathieu, Charlotte; Weigel, Annalisa

    2006-01-01

    .... Models were developed from a customer-centric perspective to assess different fractionated spacecraft architectures relative to traditional spacecraft architectures using multi-attribute analysis...

  17. Spacecraft momentum control systems

    CERN Document Server

    Leve, Frederick A; Peck, Mason A

    2015-01-01

    The goal of this book is to serve both as a practical technical reference and a resource for gaining a fuller understanding of the state of the art of spacecraft momentum control systems, specifically looking at control moment gyroscopes (CMGs). As a result, the subject matter includes theory, technology, and systems engineering. The authors combine material on system-level architecture of spacecraft that feature momentum-control systems with material about the momentum-control hardware and software. This also encompasses material on the theoretical and algorithmic approaches to the control of space vehicles with CMGs. In essence, CMGs are the attitude-control actuators that make contemporary highly agile spacecraft possible. The rise of commercial Earth imaging, the advances in privately built spacecraft (including small satellites), and the growing popularity of the subject matter in academic circles over the past decade argues that now is the time for an in-depth treatment of the topic. CMGs are augmented ...

  18. Spacecraft Material Outgassing Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This compilation of outgassing data of materials intended for spacecraft use were obtained at the Goddard Space Flight Center (GSFC), utilizing equipment developed...

  19. Spacecraft Fire Safety Demonstration

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Spacecraft Fire Safety Demonstration project is to develop and conduct large-scale fire safety experiments on an International Space Station...

  20. Quick spacecraft charging primer

    International Nuclear Information System (INIS)

    Larsen, Brian Arthur

    2014-01-01

    This is a presentation in PDF format which is a quick spacecraft charging primer, meant to be used for program training. It goes into detail about charging physics, RBSP examples, and how to identify charging.

  1. Deployable Brake for Spacecraft

    Science.gov (United States)

    Rausch, J. R.; Maloney, J. W.

    1987-01-01

    Aerodynamic shield that could be opened and closed proposed. Report presents concepts for deployable aerodynamic brake. Brake used by spacecraft returning from high orbit to low orbit around Earth. Spacecraft makes grazing passes through atmosphere to slow down by drag of brake. Brake flexible shield made of woven metal or ceramic withstanding high temperatures created by air friction. Stored until needed, then deployed by set of struts.

  2. Your Eyes

    Science.gov (United States)

    ... away? If you guessed the eye, you're right! Your eyes are at work from the moment you wake up to the ... the eye is seeing. A Muscle Makes It Work The lens is suspended in ... of the lens. That's right — the lens actually changes shape right inside your ...

  3. Internet Technology on Spacecraft

    Science.gov (United States)

    Rash, James; Parise, Ron; Hogie, Keith; Criscuolo, Ed; Langston, Jim; Powers, Edward I. (Technical Monitor)

    2000-01-01

    The Operating Missions as Nodes on the Internet (OMNI) project has shown that Internet technology works in space missions through a demonstration using the UoSAT-12 spacecraft. An Internet Protocol (IP) stack was installed on the orbiting UoSAT-12 spacecraft and tests were run to demonstrate Internet connectivity and measure performance. This also forms the basis for demonstrating subsequent scenarios. This approach provides capabilities heretofore either too expensive or simply not feasible such as reconfiguration on orbit. The OMNI project recognized the need to reduce the risk perceived by mission managers and did this with a multi-phase strategy. In the initial phase, the concepts were implemented in a prototype system that includes space similar components communicating over the TDRS (space network) and the terrestrial Internet. The demonstration system includes a simulated spacecraft with sample instruments. Over 25 demonstrations have been given to mission and project managers, National Aeronautics and Space Administration (NASA), Department of Defense (DoD), contractor technologists and other decisions makers, This initial phase reached a high point with an OMNI demonstration given from a booth at the Johnson Space Center (JSC) Inspection Day 99 exhibition. The proof to mission managers is provided during this second phase with year 2000 accomplishments: testing the use of Internet technologies onboard an actual spacecraft. This was done with a series of tests performed using the UoSAT-12 spacecraft. This spacecraft was reconfigured on orbit at very low cost. The total period between concept and the first tests was only 6 months! On board software was modified to add an IP stack to support basic IP communications. Also added was support for ping, traceroute and network timing protocol (NTP) tests. These tests show that basic Internet functionality can be used onboard spacecraft. The performance of data was measured to show no degradation from current

  4. Hummingbird - A Very Low Cost, High Delta V Spacecraft for Solar System Exploration, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Based on Microcosm's development of a high delta-V small Earth observation spacecraft called NanoEye, with a planned recurring cost of $2 million, Microcosm will...

  5. Mechanical Design of Spacecraft

    Science.gov (United States)

    1962-01-01

    In the spring of 1962, engineers from the Engineering Mechanics Division of the Jet Propulsion Laboratory gave a series of lectures on spacecraft design at the Engineering Design seminars conducted at the California Institute of Technology. Several of these lectures were subsequently given at Stanford University as part of the Space Technology seminar series sponsored by the Department of Aeronautics and Astronautics. Presented here are notes taken from these lectures. The lectures were conceived with the intent of providing the audience with a glimpse of the activities of a few mechanical engineers who are involved in designing, building, and testing spacecraft. Engineering courses generally consist of heavily idealized problems in order to allow the more efficient teaching of mathematical technique. Students, therefore, receive a somewhat limited exposure to actual engineering problems, which are typified by more unknowns than equations. For this reason it was considered valuable to demonstrate some of the problems faced by spacecraft designers, the processes used to arrive at solutions, and the interactions between the engineer and the remainder of the organization in which he is constrained to operate. These lecture notes are not so much a compilation of sophisticated techniques of analysis as they are a collection of examples of spacecraft hardware and associated problems. They will be of interest not so much to the experienced spacecraft designer as to those who wonder what part the mechanical engineer plays in an effort such as the exploration of space.

  6. Fish eye optics

    Czech Academy of Sciences Publication Activity Database

    Hudec, René; Michalová, S.

    2017-01-01

    Roč. 47, č. 2 (2017), s. 94-99 ISSN 1335-1842. [INTEGRAL/BART Workshop /14./. Karlovy Vary, 03.04.2017-07.04.2017] Grant - others:GA ČR(CZ) GA13-33324S Institutional support: RVO:67985815 Keywords : fish eye optics * lobster eye optics * X-ray monitoring Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 0.336, year: 2016

  7. Spacecraft Attitude Determination

    DEFF Research Database (Denmark)

    Bak, Thomas

    This thesis describes the development of an attitude determination system for spacecraft based only on magnetic field measurements. The need for such system is motivated by the increased demands for inexpensive, lightweight solutions for small spacecraft. These spacecraft demands full attitude...... determination based on simple, reliable sensors. Meeting these objectives with a single vector magnetometer is difficult and requires temporal fusion of data in order to avoid local observability problems. In order to guaranteed globally nonsingular solutions, quaternions are generally the preferred attitude...... is a detailed study of the influence of approximations in the modeling of the system. The quantitative effects of errors in the process and noise statistics are discussed in detail. The third contribution is the introduction of these methods to the attitude determination on-board the Ørsted satellite...

  8. Revamping Spacecraft Operational Intelligence

    Science.gov (United States)

    Hwang, Victor

    2012-01-01

    The EPOXI flight mission has been testing a new commercial system, Splunk, which employs data mining techniques to organize and present spacecraft telemetry data in a high-level manner. By abstracting away data-source specific details, Splunk unifies arbitrary data formats into one uniform system. This not only reduces the time and effort for retrieving relevant data, but it also increases operational visibility by allowing a spacecraft team to correlate data across many different sources. Splunk's scalable architecture coupled with its graphing modules also provide a solid toolset for generating data visualizations and building real-time applications such as browser-based telemetry displays.

  9. Dips spacecraft integration issues

    International Nuclear Information System (INIS)

    Determan, W.R.; Harty, R.B.

    1988-01-01

    The Department of Energy, in cooperation with the Department of Defense, has recently initiated the dynamic isotope power system (DIPS) demonstration program. DIPS is designed to provide 1 to 10 kW of electrical power for future military spacecraft. One of the near-term missions considered as a potential application for DIPS was the boost surveillance and tracking system (BSTS). A brief review and summary of the reasons behind a selection of DIPS for BSTS-type missions is presented. Many of these are directly related to spacecraft integration issues; these issues will be reviewed in the areas of system safety, operations, survivability, reliability, and autonomy

  10. Diabetes eye exams

    Science.gov (United States)

    Diabetic retinopathy - eye exams; Diabetes - eye exams; Glaucoma - diabetic eye exam; Macular edema - diabetic eye exam ... if the doctor who takes care of your diabetes checks your eyes, you need an eye exam ...

  11. The eye movements of dyslexic children during reading and visual search: impact of the visual attention span.

    Science.gov (United States)

    Prado, Chloé; Dubois, Matthieu; Valdois, Sylviane

    2007-09-01

    The eye movements of 14 French dyslexic children having a VA span reduction and 14 normal readers were compared in two tasks of visual search and text reading. The dyslexic participants made a higher number of rightward fixations in reading only. They simultaneously processed the same low number of letters in both tasks whereas normal readers processed far more letters in reading. Importantly, the children's VA span abilities related to the number of letters simultaneously processed in reading. The atypical eye movements of some dyslexic readers in reading thus appear to reflect difficulties to increase their VA span according to the task request.

  12. The Impact of Change in Visual Field on Health-Related Quality of Life: The Los Angeles Latino Eye Study

    Science.gov (United States)

    Patino, Cecilia M.; Varma, Rohit; Azen, Stanley P.; Conti, David V.; Nichol, Michael B.; McKean-Cowdin, Roberta

    2010-01-01

    Purpose To assess the impact of change in visual field (VF) on change in health related quality of life (HRQoL) at the population level. Design Prospective cohort study Participants 3,175 Los Angles Latino Eye Study (LALES) participants Methods Objective measures of VF and visual acuity and self-reported HRQoL were collected at baseline and 4-year follow-up. Analysis of covariance was used to evaluate mean differences in change of HRQoL across severity levels of change in VF and to test for effect modification by covariates. Main outcome measures General and vision-specific HRQoL. Results Of 3,175 participants, 1430 (46%) showed a change in VF (≥1 decibel [dB]) and 1651, 1715 (54%) reported a clinically important change (≥5 points) in vision-specific HRQoL. Progressive worsening and improvement in the VF were associated with increasing losses and gains in vision-specific HRQoL for the composite score and 10 of its 11 subscales (all Ptrends 5 dB and gains > 3 dB were associated with clinically meaningful losses and gains in vision-specific HRQoL, respectively. Areas of vision-specific HRQoL most affected by greater losses in VF were driving, dependency, role-functioning, and mental health. The effect of change in VF (loss or gain) on mean change in vision-specific HRQoL varied by level of baseline vision loss (in visual field and/or visual acuity) and by change in visual acuity (all P-interactions 5 dB loss in visual field during the study period had a mean loss of vision-specific HRQoL of 11.3 points, while those with no VF loss at baseline had a mean loss of 0.97 points Similarly, with a > 5 dB loss in VF and baseline visual acuity impairment (mild/severe) there was a loss in vision-specific HRQoL of 10.5 points, whereas with no visual acuity impairment at baseline there was a loss of vision-specific HRQoL of 3.7 points. Conclusion Both losses and gains in VF produce clinically meaningful changes in vision-specific HRQoL. In the presence of pre-existing vision

  13. How to make an eye unit child friendly

    Directory of Open Access Journals (Sweden)

    Joan McLeod-Omawale

    2010-03-01

    Full Text Available Meeting the needs of children and their parents in an eye unit, whether at primary, district, or tertiary level, has a significant impact on the eye team’s ability to provide good quality eye care.

  14. Spacecraft charging and related effects during Halley encounter

    International Nuclear Information System (INIS)

    Young, D.T.

    1983-01-01

    Hypervelocity (69 km/s) impact of cometary material with surfaces of the GIOTTO spacecraft will induce a number of spurious and possibly harmful phenomena. The most serious of these is likely to be spacecraft charging that results from impact-produced plasma distributions surrounding GIOTTO. The ESA Plasma Environment Working Group, whose studies are the basis for this report, finds that charging may become significant within approx. 10 5 km of the nucleus where potentials of approx. = +20 V are to be expected. In addition to spacecraft charging, impact produced plasma may interfere with in situ plasma measurements, particularly those of ion plasma analyzers and mass spectrometers

  15. Spacecraft Thermal Management

    Science.gov (United States)

    Hurlbert, Kathryn Miller

    2009-01-01

    In the 21st century, the National Aeronautics and Space Administration (NASA), the Russian Federal Space Agency, the National Space Agency of Ukraine, the China National Space Administration, and many other organizations representing spacefaring nations shall continue or newly implement robust space programs. Additionally, business corporations are pursuing commercialization of space for enabling space tourism and capital business ventures. Future space missions are likely to include orbiting satellites, orbiting platforms, space stations, interplanetary vehicles, planetary surface missions, and planetary research probes. Many of these missions will include humans to conduct research for scientific and terrestrial benefits and for space tourism, and this century will therefore establish a permanent human presence beyond Earth s confines. Other missions will not include humans, but will be autonomous (e.g., satellites, robotic exploration), and will also serve to support the goals of exploring space and providing benefits to Earth s populace. This section focuses on thermal management systems for human space exploration, although the guiding principles can be applied to unmanned space vehicles as well. All spacecraft require a thermal management system to maintain a tolerable thermal environment for the spacecraft crew and/or equipment. The requirements for human rating and the specified controlled temperature range (approximately 275 K - 310 K) for crewed spacecraft are unique, and key design criteria stem from overall vehicle and operational/programatic considerations. These criteria include high reliability, low mass, minimal power requirements, low development and operational costs, and high confidence for mission success and safety. This section describes the four major subsystems for crewed spacecraft thermal management systems, and design considerations for each. Additionally, some examples of specialized or advanced thermal system technologies are presented

  16. Eye Injuries

    Science.gov (United States)

    ... that you could lose your vision. Most eye injuries are preventable. If you play sports or work in certain jobs, you may need protection. The most common type of injury happens when something irritates the ...

  17. Eyes - bulging

    Science.gov (United States)

    ... different ages. In: Lambert SR, Lyons CJ, eds. Taylor and Hoyt's Pediatric Ophthalmology and Strabismus . 5th ed. Philadelphia, PA: Elsevier; 2017:chap 96. Orge FH, Grigorian F. Examination and common problems of the neonatal eye. ...

  18. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Stories Español Eye Health / Eye Health A-Z Dry Eye Sections What Is Dry Eye? Dry Eye Symptoms ... of Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué es el ojo seco? ...

  19. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Español Eye Health / Eye Health A-Z Dry Eye Sections What Is Dry Eye? Dry Eye Symptoms ... Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué es el ojo seco? ...

  20. Spacecraft exploration of asteroids

    International Nuclear Information System (INIS)

    Veverka, J.; Langevin, Y.; Farquhar, R.; Fulchignoni, M.

    1989-01-01

    After two decades of spacecraft exploration, we still await the first direct investigation of an asteroid. This paper describes how a growing international interest in the solar system's more primitive bodies should remedy this. Plans are under way in Europe for a dedicated asteroid mission (Vesta) which will include multiple flybys with in situ penetrator studies. Possible targets include 4 Vesta, 8 Flora and 46 Hestia; launch its scheduled for 1994 or 1996. In the United States, NASA plans include flybys of asteroids en route to outer solar system targets

  1. Spacecraft rendezvous and docking

    DEFF Research Database (Denmark)

    Jørgensen, John Leif

    1999-01-01

    The phenomenons and problems encountered when a rendezvous manoeuvre, and possible docking, of two spacecrafts has to be performed, have been the topic for numerous studies, and, details of a variety of scenarios has been analysed. So far, all solutions that has been brought into realization has...... been based entirely on direct human supervision and control. This paper describes a vision-based system and methodology, that autonomously generates accurate guidance information that may assist a human operator in performing the tasks associated with both the rendezvous and docking navigation...

  2. Toward autonomous spacecraft

    Science.gov (United States)

    Fogel, L. J.; Calabrese, P. G.; Walsh, M. J.; Owens, A. J.

    1982-01-01

    Ways in which autonomous behavior of spacecraft can be extended to treat situations wherein a closed loop control by a human may not be appropriate or even possible are explored. Predictive models that minimize mean least squared error and arbitrary cost functions are discussed. A methodology for extracting cyclic components for an arbitrary environment with respect to usual and arbitrary criteria is developed. An approach to prediction and control based on evolutionary programming is outlined. A computer program capable of predicting time series is presented. A design of a control system for a robotic dense with partially unknown physical properties is presented.

  3. Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

    Science.gov (United States)

    DeSimpelaere, Edward

    2011-01-01

    The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a

  4. SQCX X-ray Observations Of The Deep Impact Spacecraft Close Encounters With Comets 9P/Tempel 1 And 103P/Hartley 2

    Science.gov (United States)

    Lisse, Carey M.; Dennerl, K.; Wolk, S. J.; Christian, D. J.; Bodewits, D.; Zurbuchen, T. H.; Combi, M.

    2010-03-01

    We present results from the extensive Chandra, SWIFT, Spitzer, and groundbased observing campaigns studying Comet 9P/Tempel 1 in support of NASA's Deep Impact (DI) mission as an indication of the results expected for the next DI flyby of comet 103P/Hartley 2 at 0.1 AU geocentric distance in November 2010. 9P/Tempel 1 was observed for 300 ksec between 30th June and 24th July 2005, and continuously for 60 ksec on July 4th during the impact event. X-ray emission qualitatively similar to that observed for the collisionally thin, cold wind comet 2P/Encke system (Lisse et al. 2005) was found, with emission morphology centered on the nucleus and emission lines due to C, N, O, and Ne solar wind minor ions. The comet was relatively faint on July 4th, and the total increase in x-ray flux due to the Deep Impact excavation was small, 20% of the immediate pre-impact value, consistent with estimates that the total coma neutral gas release due to the impact was 5 x 106 kg ( 10 hrs of normal coma outflow). Over time, other temporally variable spectral features due to changing solar wind flux densities and charge states were clearly seen. Good agreement between the Chandra and SWIFT x-ray photometry was found. Two flares, much stronger than the man-made increase due to Deep Impact, were found in the observed x-rays on June 30th and July 8th, 2005, and are coincident with increases in the solar wind flux arriving at the comet. Modeling of the Chandra data using observed Spitzer gas production rates and ACE solar wind ion fluxes with a SWCX mechanism for the emission was found to be consistent with the temporal- and spectral behavior expected for a slow, hot wind typical of low latitude emission from the solar corona interacting with the comet's neutral coma.

  5. Eye emergencies

    Science.gov (United States)

    ... eye can be caused by a work-related accident. It can also be caused by common household ... hammers, or other striking tools Working with toxic chemicals Cycling or when in windy and ... A.D.A.M.'s editorial policy , editorial process and privacy policy . A.D.A.M. is ...

  6. Eye Cancer

    Science.gov (United States)

    ... layer of tissue underneath the retina that contains connective tissue and melanocytes, which are pigmented (colored) cells, and nourishes the inside of the eye. The choroid is the most common site for a tumor. Types of intraocular cancer The most common intraocular cancer in adults is ...

  7. Eye trauma

    African Journals Online (AJOL)

    2011-02-02

    Feb 2, 2011 ... Note your findings in an orderly fashion: orbit, lids, conjunctiva, cornea, anterior chamber, iris, pupil reaction, lens, fundus. • Stain cornea with fluorescein. It is advisable to examine the eye as soon as possible since a delay will invariably lead to lid swelling, making the examination far more difficult. This can ...

  8. Research-Based Monitoring, Prediction, and Analysis Tools of the Spacecraft Charging Environment for Spacecraft Users

    Science.gov (United States)

    Zheng, Yihua; Kuznetsova, Maria M.; Pulkkinen, Antti A.; Maddox, Marlo M.; Mays, Mona Leila

    2015-01-01

    The Space Weather Research Center (http://swrc. gsfc.nasa.gov) at NASA Goddard, part of the Community Coordinated Modeling Center (http://ccmc.gsfc.nasa.gov), is committed to providing research-based forecasts and notifications to address NASA's space weather needs, in addition to its critical role in space weather education. It provides a host of services including spacecraft anomaly resolution, historical impact analysis, real-time monitoring and forecasting, tailored space weather alerts and products, and weekly summaries and reports. In this paper, we focus on how (near) real-time data (both in space and on ground), in combination with modeling capabilities and an innovative dissemination system called the integrated Space Weather Analysis system (http://iswa.gsfc.nasa.gov), enable monitoring, analyzing, and predicting the spacecraft charging environment for spacecraft users. Relevant tools and resources are discussed.

  9. Evaluation of spacecraft technology programs (effects on communication satellite business ventures), volume 2

    Science.gov (United States)

    Greenburg, J. S.; Kaplan, M.; Fishman, J.; Hopkins, C.

    1985-01-01

    The computational procedures used in the evaluation of spacecraft technology programs that impact upon commercial communication satellite operations are discussed. Computer programs and data bases are described.

  10. Small Spacecraft for Planetary Science

    Science.gov (United States)

    Baker, John; Castillo-Rogez, Julie; Bousquet, Pierre-W.; Vane, Gregg; Komarek, Tomas; Klesh, Andrew

    2016-07-01

    As planetary science continues to explore new and remote regions of the Solar system with comprehensive and more sophisticated payloads, small spacecraft offer the possibility for focused and more affordable science investigations. These small spacecraft or micro spacecraft (attitude control and determination, capable computer and data handling, and navigation are being met by technologies currently under development to be flown on CubeSats within the next five years. This paper will discuss how micro spacecraft offer an attractive alternative to accomplish specific science and technology goals and what relevant technologies are needed for these these types of spacecraft. Acknowledgements: Part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to NASA. Government sponsorship acknowledged.

  11. Diabetic Eye Disease

    Science.gov (United States)

    ... Disease, & Other Dental Problems Diabetes & Sexual & Urologic Problems Diabetic Eye Disease What is diabetic eye disease? Diabetic eye disease is a group ... eye diseases that can threaten your sight are Diabetic retinopathy The retina is the inner lining at ...

  12. About the Eye

    Medline Plus

    Full Text Available ... eye behind the iris that helps to focus light on the retina. It allows the eye to ... of the eye. It regulates the amount of light entering the eye through the pupil. Pupil (PYOO- ...

  13. Eye Movement Disorders

    Science.gov (United States)

    ... work properly. There are many kinds of eye movement disorders. Two common ones are Strabismus - a disorder ... in "crossed eyes" or "walleye." Nystagmus - fast, uncontrollable movements of the eyes, sometimes called "dancing eyes" Some ...

  14. About the Eye

    Medline Plus

    Full Text Available ... for Kids >> About the Eye Listen All About Vision About the Eye Ask a Scientist Video Series ... Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear Sports and Your Eyes Fun ...

  15. Why Do Eyes Water?

    Science.gov (United States)

    ... for Educators Search English Español Why Do Eyes Water? KidsHealth / For Kids / Why Do Eyes Water? What's ... coming out of your nose. Why Do Eyes Water? Eyes water for lots of different reasons besides ...

  16. Spacecraft fabrication and test MODIL. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Saito, T.T.

    1994-05-01

    This report covers the period from October 1992 through the close of the project. FY 92 closed out with the successful briefing to industry and with many potential and important initiatives in the spacecraft arena. Due to the funding uncertainties, we were directed to proceed as if our funding would be approximately the same as FY 92 ($2M), but not to make any major new commitments. However, the MODIL`s FY 93 funding was reduced to $810K and we were directed to concentrate on the cryocooler area. The cryocooler effort completed its demonstration project. The final meetings with the cryocooler fabricators were very encouraging as we witnessed the enthusiastic reception of technology to help them reduce fabrication uncertainties. Support of the USAF Phillips Laboratory cryocooler program was continued including kick-off meetings for the Prototype Spacecraft Cryocooler (PSC). Under Phillips Laboratory support, Gill Cruz visited British Aerospace and Lucas Aerospace in the United Kingdom to assess their manufacturing capabilities. In the Automated Spacecraft & Assembly Project (ASAP), contracts were pursued for the analysis by four Brilliant Eyes prime contractors to provide a proprietary snap shot of their current status of Integrated Product Development. In the materials and structure thrust the final analysis was completed of the samples made under the contract (``Partial Automation of Matched Metal Net Shape Molding of Continuous Fiber Composites``) to SPARTA. The Precision Technologies thrust funded the Jet Propulsion Laboratory to prepare a plan to develop a Computer Aided Alignment capability to significantly reduce the time for alignment and even possibly provide real time and remote alignment capability of systems in flight.

  17. Through our children's eyes--the public health impact of the vision screening requirements for Indiana school children.

    Science.gov (United States)

    Marshall, Edwin C; Meetz, Richard E; Harmon, L'erin L

    2010-02-01

    The vision screening of preschool and school children is a widely accepted procedure to detect vision problems that can interfere with learning. The Indiana General Assembly requires the annual vision screening with the Modified Clinical Technique (MCT) of all children upon their enrollment in either kindergarten or the first grade, with the exception of schools that apply for and receive waivers to conduct only a distance Snellen chart screening. In association with the Indiana State Department of Health, the Indiana University School of Optometry conducted an analysis of statewide school screening data on 36,967 grade 1 children from 139 of the 294 Indiana school corporations that submitted data for the 2000-2001 school year to examine differences in referral rate by screening method, the socioeconomic status of children screened, and academic performance. The MCT was used by 125 of the school corporations, and some other technique was used by 14 school corporations. Significant differences were seen when comparing the mean referral rates of school corporations that conduct the MCT against school corporations that do not conduct the MCT (P = 0.001) and in the rate of referral by median family income of the children screened (P = 0.050). A median family income of $46,500 was identified as the level at which the income-specific difference in referral rates ceased to be significant (P = 0.074). In spite of an observed tendency toward a higher referral rate for children who performed below average on the standardized Indiana Statewide Testing for Educational Progress Plus (ISTEP+) exam, results were found to be not significant (P = 0.116) when comparing the percentage of grade 1 children referred to an eye care provider in 2000-2001 with their percentages of passing both the English/language arts and mathematics components of the 2002-2003 ISTEP+ exam (in grade 3). Schools using the highly sensitive and specific MCT identified more visually at-risk children than

  18. Printed Spacecraft Separation System

    Energy Technology Data Exchange (ETDEWEB)

    Dehoff, Ryan R [ORNL; Holmans, Walter [Planetary Systems Corporation

    2016-10-01

    In this project Planetary Systems Corporation proposed utilizing additive manufacturing (3D printing) to manufacture a titanium spacecraft separation system for commercial and US government customers to realize a 90% reduction in the cost and energy. These savings were demonstrated via “printing-in” many of the parts and sub-assemblies into one part, thus greatly reducing the labor associated with design, procurement, assembly and calibration of mechanisms. Planetary Systems Corporation redesigned several of the components of the separation system based on additive manufacturing principles including geometric flexibility and the ability to fabricate complex designs, ability to combine multiple parts of an assembly into a single component, and the ability to optimize design for specific mechanical property targets. Shock absorption was specifically targeted and requirements were established to attenuate damage to the Lightband system from shock of initiation. Planetary Systems Corporation redesigned components based on these requirements and sent the designs to Oak Ridge National Laboratory to be printed. ORNL printed the parts using the Arcam electron beam melting technology based on the desire for the parts to be fabricated from Ti-6Al-4V based on the weight and mechanical performance of the material. A second set of components was fabricated from stainless steel material on the Renishaw laser powder bed technology due to the improved geometric accuracy, surface finish, and wear resistance of the material. Planetary Systems Corporation evaluated these components and determined that 3D printing is potentially a viable method for achieving significant cost and savings metrics.

  19. Spectra and spacecraft

    Science.gov (United States)

    Moroz, V. I.

    2001-02-01

    In June 1999, Dr. Regis Courtin, Associate Editor of PSS, suggested that I write an article for the new section of this journal: "Planetary Pioneers". I hesitated , but decided to try. One of the reasons for my doubts was my primitive English, so I owe the reader an apology for this in advance. Writing took me much more time than I supposed initially, I have stopped and again returned to manuscript many times. My professional life may be divided into three main phases: pioneering work in ground-based IR astronomy with an emphasis on planetary spectroscopy (1955-1970), studies of the planets with spacecraft (1970-1989), and attempts to proceed with this work in difficult times. I moved ahead using the known method of trials and errors as most of us do. In fact, only a small percentage of efforts led to some important results, a sort of dry residue. I will try to describe below how has it been in my case: what may be estimated as the most important, how I came to this, what was around, etc.

  20. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Eye Health A-Z Symptoms Glasses & Contacts Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye ... Eye Symptoms Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué ...

  1. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Eye? Dry Eye Symptoms Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué ... Inside of Your Eyelid Nov 29, 2017 New Dry Eye Treatment is a Tear-Jerker Jul 21, 2017 Three ...

  2. What Is Dry Eye?

    Science.gov (United States)

    ... Eye? Dry Eye Symptoms Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué ... Inside of Your Eyelid Nov 29, 2017 New Dry Eye Treatment is a Tear-Jerker Jul 21, 2017 Three ...

  3. Particle-in-Cell Simulation Study on the Floating Potential of Spacecraft in the Low Earth Orbit

    International Nuclear Information System (INIS)

    Tang Daotan; Yang Shengsheng; Zheng Kuohai; Qin Xiaogang; Li Detian; Liu Qing; Zhao Chengxuan; Du Shanshan

    2015-01-01

    In order to further understand the characteristics of the floating potential of low earth orbit spacecraft, the effects of the electron current collection area, background electron temperature, photocurrent emission, spacecraft wake, and the shape of spacecraft on spacecraft floating potential were studied here by particle-in-cell simulation in the low earth orbit. The simulation results show that the electron current collection area and background electron temperature impact on the floating potential by changing the electron current collection of spacecraft. By increasing the electron current collection area or background electron temperature, the spacecraft will float at a lower electric potential with respect to the surrounding plasma. However, the spacecraft wake affects the floating potential by increasing the ion current collected by spacecraft. The emission of the photocurrent from the spacecraft surface, which compensates for the electrons collected from background plasma, causes the floating potential to increase. The shape of the spacecraft is also an important factor influencing the floating potential. (paper)

  4. Modelling the impact of blood flow on the temperature distribution in the human eye and the orbit: fixed heat transfer coefficients versus the Pennes bioheat model versus discrete blood vessels

    Energy Technology Data Exchange (ETDEWEB)

    Flyckt, V M M; Raaymakers, B W; Lagendijk, J J W [Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)

    2006-10-07

    Prediction of the temperature distribution in the eye depends on how the impact of the blood flow is taken into account. Three methods will be compared: a simplified eye anatomy that applies a single heat transfer coefficient to describe all heat transport mechanisms between the sclera and the body core, a detailed eye anatomy in which the blood flow is accounted for either by the bioheat approach, or by including the discrete vasculature in the eye and the orbit. The comparison is done both for rabbit and human anatomies, normo-thermally and when exposed to homogeneous power densities. The first simplified model predicts much higher temperatures than the latter two. It was shown that the eye is very hard to heat when taking physiological perfusion correctly into account. It was concluded that the heat transfer coefficient describing the heat transport from the sclera to the body core reported in the literature for the first simplified model is too low. The bioheat approach is appropriate for a first-order approximation of the temperature distribution in the eye when exposed to a homogeneous power density, but the discrete vasculature down to 0.2 mm in diameter needs to be taken into account when the heterogeneity of the temperature distribution at a mm scale is of interest.

  5. Modelling the impact of blood flow on the temperature distribution in the human eye and the orbit: fixed heat transfer coefficients versus the Pennes bioheat model versus discrete blood vessels

    International Nuclear Information System (INIS)

    Flyckt, V M M; Raaymakers, B W; Lagendijk, J J W

    2006-01-01

    Prediction of the temperature distribution in the eye depends on how the impact of the blood flow is taken into account. Three methods will be compared: a simplified eye anatomy that applies a single heat transfer coefficient to describe all heat transport mechanisms between the sclera and the body core, a detailed eye anatomy in which the blood flow is accounted for either by the bioheat approach, or by including the discrete vasculature in the eye and the orbit. The comparison is done both for rabbit and human anatomies, normo-thermally and when exposed to homogeneous power densities. The first simplified model predicts much higher temperatures than the latter two. It was shown that the eye is very hard to heat when taking physiological perfusion correctly into account. It was concluded that the heat transfer coefficient describing the heat transport from the sclera to the body core reported in the literature for the first simplified model is too low. The bioheat approach is appropriate for a first-order approximation of the temperature distribution in the eye when exposed to a homogeneous power density, but the discrete vasculature down to 0.2 mm in diameter needs to be taken into account when the heterogeneity of the temperature distribution at a mm scale is of interest

  6. Evaluation of Ultrafiltration for Spacecraft Water Reuse

    Science.gov (United States)

    Pickering, Karen D.; Wiesner, Mark R.

    2001-01-01

    Ultrafiltration is examined for use as the first stage of a primary treatment process for spacecraft wastewater. It is hypothesized that ultrafiltration can effectively serve as pretreatment for a reverse osmosis system, removing the majority of organic material in a spacecraft wastewater. However, it is believed that the interaction between the membrane material and the surfactant found in the wastewater will have a significant impact on the fouling of the ultrafiltration membrane. In this study, five different ultrafiltration membrane materials are examined for the filtration of wastewater typical of that expected to be produced onboard the International Space Station. Membranes are used in an unstirred batch cell. Flux, organic carbon rejection, and recovery from fouling are measured. The results of this evaluation will be used to select the most promising membranes for further study.

  7. TTEthernet for Integrated Spacecraft Networks

    Science.gov (United States)

    Loveless, Andrew

    2015-01-01

    Aerospace projects have traditionally employed federated avionics architectures, in which each computer system is designed to perform one specific function (e.g. navigation). There are obvious downsides to this approach, including excessive weight (from so much computing hardware), and inefficient processor utilization (since modern processors are capable of performing multiple tasks). There has therefore been a push for integrated modular avionics (IMA), in which common computing platforms can be leveraged for different purposes. This consolidation of multiple vehicle functions to shared computing platforms can significantly reduce spacecraft cost, weight, and design complexity. However, the application of IMA principles introduces significant challenges, as the data network must accommodate traffic of mixed criticality and performance levels - potentially all related to the same shared computer hardware. Because individual network technologies are rarely so competent, the development of truly integrated network architectures often proves unreasonable. Several different types of networks are utilized - each suited to support a specific vehicle function. Critical functions are typically driven by precise timing loops, requiring networks with strict guarantees regarding message latency (i.e. determinism) and fault-tolerance. Alternatively, non-critical systems generally employ data networks prioritizing flexibility and high performance over reliable operation. Switched Ethernet has seen widespread success filling this role in terrestrial applications. Its high speed, flexibility, and the availability of inexpensive commercial off-the-shelf (COTS) components make it desirable for inclusion in spacecraft platforms. Basic Ethernet configurations have been incorporated into several preexisting aerospace projects, including both the Space Shuttle and International Space Station (ISS). However, classical switched Ethernet cannot provide the high level of network

  8. Spacecraft Charging and the Microwave Anisotropy Probe Spacecraft

    Science.gov (United States)

    Timothy, VanSant J.; Neergaard, Linda F.

    1998-01-01

    The Microwave Anisotropy Probe (MAP), a MIDEX mission built in partnership between Princeton University and the NASA Goddard Space Flight Center (GSFC), will study the cosmic microwave background. It will be inserted into a highly elliptical earth orbit for several weeks and then use a lunar gravity assist to orbit around the second Lagrangian point (L2), 1.5 million kilometers, anti-sunward from the earth. The charging environment for the phasing loops and at L2 was evaluated. There is a limited set of data for L2; the GEOTAIL spacecraft measured relatively low spacecraft potentials (approx. 50 V maximum) near L2. The main area of concern for charging on the MAP spacecraft is the well-established threat posed by the "geosynchronous region" between 6-10 Re. The launch in the autumn of 2000 will coincide with the falling of the solar maximum, a period when the likelihood of a substorm is higher than usual. The likelihood of a substorm at that time has been roughly estimated to be on the order of 20% for a typical MAP mission profile. Because of the possibility of spacecraft charging, a requirement for conductive spacecraft surfaces was established early in the program. Subsequent NASCAP/GEO analyses for the MAP spacecraft demonstrated that a significant portion of the sunlit surface (solar cell cover glass and sunshade) could have nonconductive surfaces without significantly raising differential charging. The need for conductive materials on surfaces continually in eclipse has also been reinforced by NASCAP analyses.

  9. Eye Contricks

    Directory of Open Access Journals (Sweden)

    N Wade

    2011-04-01

    Full Text Available Icons are eye-cons: they provide a distillation of a complex object or idea into a simple pictorial shape. They create the impression of representing that which cannot be presented. Even at the level of the photograph, the links between icon and object are tenuous. The dimension of distance or depth is missing from the icon, and this alone introduces all manner of potential ambiguities. The history of art can be considered as an exploration of the missing link between icon and object. Eye-cons are more honest—they are tricks of vision so that what is seen does not necessarily correspond to what is presented. They are visual allusions rather than visual illusions, although they can display illusory effects. At its broadest, icon can be equated with image. The concept of image has thrived on its vagueness, and so attempts have been made to refine it. An icon corresponds to an optical image: it shares some of the projective characteristics of the object represented. Written words are also icons but they do not resemble the objects they represent—they are stylised or conventional rather than spatialised and projective. Words and images were set in delightful opposition by René Magritte (1898-1967 in a series of pipe paintings, and he also played on the theme of the arbitrariness of the verbal labels assigned to objects. What is surprising is that Magritte did not apply his painterly skills to transforming the word shapes he used. A similar reluctance to transform the typefaces pervades visual poetry. My interests are in the visual rather than the poetic dimension, and I will present a range of my own eye contricks which play with letter and word shapes in a variety of ways.

  10. Spacecraft Environmental Interactions Technology, 1983

    Science.gov (United States)

    1985-01-01

    State of the art of environment interactions dealing with low-Earth-orbit plasmas; high-voltage systems; spacecraft charging; materials effects; and direction of future programs are contained in over 50 papers.

  11. Gravity Probe B spacecraft description

    International Nuclear Information System (INIS)

    Bennett, Norman R; Burns, Kevin; Katz, Russell; Kirschenbaum, Jon; Mason, Gary; Shehata, Shawky

    2015-01-01

    The Gravity Probe B spacecraft, developed, integrated, and tested by Lockheed Missiles and Space Company and later Lockheed Martin Corporation, consisted of structures, mechanisms, command and data handling, attitude and translation control, electrical power, thermal control, flight software, and communications. When integrated with the payload elements, the integrated system became the space vehicle. Key requirements shaping the design of the spacecraft were: (1) the tight mission timeline (17 months, 9 days of on-orbit operation), (2) precise attitude and translational control, (3) thermal protection of science hardware, (4) minimizing aerodynamic, magnetic, and eddy current effects, and (5) the need to provide a robust, low risk spacecraft. The spacecraft met all mission requirements, as demonstrated by dewar lifetime meeting specification, positive power and thermal margins, precision attitude control and drag-free performance, reliable communications, and the collection of more than 97% of the available science data. (paper)

  12. Intelligent spacecraft module

    Science.gov (United States)

    Oungrinis, Konstantinos-Alketas; Liapi, Marianthi; Kelesidi, Anna; Gargalis, Leonidas; Telo, Marinela; Ntzoufras, Sotiris; Paschidi, Mariana

    2014-12-01

    The paper presents the development of an on-going research project that focuses on a human-centered design approach to habitable spacecraft modules. It focuses on the technical requirements and proposes approaches on how to achieve a spatial arrangement of the interior that addresses sufficiently the functional, physiological and psychosocial needs of the people living and working in such confined spaces that entail long-term environmental threats to human health and performance. Since the research perspective examines the issue from a qualitative point of view, it is based on establishing specific relationships between the built environment and its users, targeting people's bodily and psychological comfort as a measure toward a successful mission. This research has two basic branches, one examining the context of the system's operation and behavior and the other in the direction of identifying, experimenting and formulating the environment that successfully performs according to the desired context. The latter aspect is researched upon the construction of a scaled-model on which we run series of tests to identify the materiality, the geometry and the electronic infrastructure required. Guided by the principles of sensponsive architecture, the ISM research project explores the application of the necessary spatial arrangement and behavior for a user-centered, functional interior where the appropriate intelligent systems are based upon the existing mechanical and chemical support ones featured on space today, and especially on the ISS. The problem is set according to the characteristics presented at the Mars500 project, regarding the living quarters of six crew-members, along with their hygiene, leisure and eating areas. Transformable design techniques introduce spatial economy, adjustable zoning and increased efficiency within the interior, securing at the same time precise spatial orientation and character at any given time. The sensponsive configuration is

  13. Nutrition and the eye.

    Science.gov (United States)

    Congdon, N G; West, K P

    1999-12-01

    The topic "nutrition and the eye" cannot adequately be covered in a single review article; indeed, dozens of books and hundreds of articles have been written on the subject. This review concentrates on three areas in which specific nutrients are known or theorized to have a major impact on vision and the visual system: vitamin A deficiency; antioxidants and their proposed role in the prevention of age-related cataract and macular degeneration; and nutritional optic neuropathies, including those of the recent Cuban epidemic. In addition, this article touches on nutritional treatments that have been suggested for several less common eye diseases and, finally, considers several less prevalent conditions in which deficiency of or excess exposure to a particular nutrient has been associated with ocular pathology.

  14. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye Health / Eye Health A-Z Dry Eye ... Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué es el ojo seco? Written By: Kierstan ...

  15. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Eye Symptoms Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué ... Your Eyelid Nov 29, 2017 New Dry Eye Treatment is a Tear-Jerker Jul 21, 2017 Three ...

  16. Bags Under Eyes

    Science.gov (United States)

    Bags under eyes Overview Bags under eyes — mild swelling or puffiness under the eyes — are common as you age. With aging, the tissues around your ... space below your eyes, adding to the swelling. Bags under eyes are usually a cosmetic concern and ...

  17. About the Eye

    Medline Plus

    Full Text Available ... Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear Sports and Your Eyes Fun Stuff Cool Eye Tricks Links to More Information Optical Illusions Printables About the Eye Your eyes ...

  18. THE MUSLIM FAMILY BETWEEN MYTHS AND SOCIAL IMPACT, SEEN TROUGH THE EYES OF A NON – MUSLIM

    Directory of Open Access Journals (Sweden)

    MIRELA CRISTIANA NILĂ STRATONE

    2013-05-01

    Full Text Available This study is part of an extensive analysis of the social impact caused by the characteristics of the Muslim family in the Romanian and European society. Between the religious and the social demands, Muslim family manages all the harder to enroll in the course imposed by tradition. A great importance has the knowledge and the understanding of the intra and interfamilial behaviors, this one needs first to detect and to avoid the myths related to the Muslim family. Addressing and clarifying this issue lies in the center of the present study. He represents a necessity without which Muslim family life, the role of the woman and the man in this family can not be understood fully, given that their religion and their way of life tend to cover an area of increasingly greater psychosocial space both at European level and worldwide.

  19. The socioeconomic impact of human immunodeficiency virus / acquired immune deficiency syndrome in India and its relevance to eye care.

    Science.gov (United States)

    Murthy, Gvs

    2008-01-01

    Human immunodeficiency virus (HIV) infection is aptly called the modern day 'plague' and has the potential to decimate people in the productive age group. On the other hand, the increasing life expectancy in developing countries spirals age-related blindness. One therefore reduces economic productivity while the other increases economic dependency. Both lead to increased expenditure of households though in different proportions. Human immunodeficiency virus and blindness are both associated with discrimination, stigma and long-term consequences. They impact the socioeconomic fabric of the affected individuals, communities and countries. The loss in productivity and the cost of support to the affected individuals are seen in both. Each is a potent problem on its own but together they spell disaster in geometric proportions rather than a simple additive effect. Strategies need to be evolved to provide solace and improve the quality of life of an HIV-positive blind individual.

  20. The socioeconomic impact of human immunodeficiency virus / acquired immune deficiency syndrome in India and its relevance to eye care

    Directory of Open Access Journals (Sweden)

    Murthy GVS

    2008-01-01

    Full Text Available Human immunodeficiency virus (HIV infection is aptly called the modern day ′plague′ and has the potential to decimate people in the productive age group. On the other hand, the increasing life expectancy in developing countries spirals age-related blindness. One therefore reduces economic productivity while the other increases economic dependency. Both lead to increased expenditure of households though in different proportions. Human immunodeficiency virus and blindness are both associated with discrimination, stigma and long-term consequences. They impact the socioeconomic fabric of the affected individuals, communities and countries. The loss in productivity and the cost of support to the affected individuals are seen in both. Each is a potent problem on its own but together they spell disaster in geometric proportions rather than a simple additive effect. Strategies need to be evolved to provide solace and improve the quality of life of an HIV-positive blind individual.

  1. About the Eye

    Medline Plus

    Full Text Available ... your eye. It helps your eye focus light so things look sharp and clear. Sclera (SKLEH-ruh) ... the different parts of your eye work together so you can see and make sense of the ...

  2. About the Eye

    Medline Plus

    Full Text Available ... Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision ... to More Information Optical Illusions Printables About the Eye Your eyes are made up of many different ...

  3. Fluorescein eye stain

    Science.gov (United States)

    Abnormal results may point to: Abnormal tear production (dry eye) Blocked tear duct Corneal abrasion (a scratch on ... object in eye ) Infection Injury or trauma Severe dry eye associated with arthritis (keratoconjunctivitis sicca)

  4. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Member Services Advocacy Foundation About Subspecialties & More Eye Health Home Annual Meeting Clinical Education Practice Management Member ... Center Redmond Ethics Center Global Ophthalmology Guide Eye Health Find an Ophthalmologist Academy Store Eye Health A- ...

  5. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Ophthalmology/Strabismus Ocular Pathology/Oncology Oculoplastics/Orbit Refractive Management/Intervention Retina/Vitreous Uveitis Focus On ... Dry Eye Sections What Is Dry Eye? Dry Eye Symptoms Causes of ...

  6. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Dry Eye Symptoms Related Ask an Ophthalmologist Answers Can a six-month dissolvable punctal plug be removed ... my eyes dry after LASIK? Jun 19, 2016 Can I be tested whether I close my eyes ...

  7. Eye Injuries at Work

    Science.gov (United States)

    ... National Standards Institute (ANSI) to meet their eye protection standards. If an eye injury occurs, see an ophthalmologist or go to the emergency room immediately, even if the eye injury appears minor. Delaying medical attention can result in permanent vision ...

  8. EyeGENE

    Data.gov (United States)

    U.S. Department of Health & Human Services — The eyeGENE® Biorepository and corresponding Database contain family history and clinical eye exam data from subjects enrolled in eyeGENE® Program coupled to...

  9. Artist concept of Galileo spacecraft

    Science.gov (United States)

    1988-01-01

    Galileo spacecraft is illustrated in artist concept. Gallileo, named for the Italian astronomer, physicist and mathematician who is credited with construction of the first complete, practical telescope in 1620, will make detailed studies of Jupiter. A cooperative program with the Federal Republic of Germany the Galileo mission will amplify information acquired by two Voyager spacecraft in their brief flybys. Galileo is a two-element system that includes a Jupiter-orbiting observatory and an entry probe. Jet Propulsion Laboratory (JPL) is Galileo project manager and builder of the main spacecraft. Ames Research Center (ARC) has responsibility for the entry probe, which was built by Hughes Aircraft Company and General Electric. Galileo will be deployed from the payload bay (PLB) of Atlantis, Orbiter Vehicle (OV) 104, during mission STS-34.

  10. Training for spacecraft technical analysts

    Science.gov (United States)

    Ayres, Thomas J.; Bryant, Larry

    1989-01-01

    Deep space missions such as Voyager rely upon a large team of expert analysts who monitor activity in the various engineering subsystems of the spacecraft and plan operations. Senior teammembers generally come from the spacecraft designers, and new analysts receive on-the-job training. Neither of these methods will suffice for the creation of a new team in the middle of a mission, which may be the situation during the Magellan mission. New approaches are recommended, including electronic documentation, explicit cognitive modeling, and coached practice with archived data.

  11. Yarbus, Eye Movements, and Vision

    Directory of Open Access Journals (Sweden)

    Benjamin W Tatler

    2010-04-01

    Full Text Available The impact of Yarbus's research on eye movements was enormous following the translation of his book Eye Movements and Vision into English in 1967. In stark contrast, the published material in English concerning his life is scant. We provide a brief biography of Yarbus and assess his impact on contemporary approaches to research on eye movements. While early interest in his work focused on his study of stabilised retinal images, more recently this has been replaced with interest in his work on the cognitive influences on scanning patterns. We extended his experiment on the effect of instructions on viewing a picture using a portrait of Yarbus rather than a painting. The results obtained broadly supported those found by Yarbus.

  12. Results from active spacecraft potential control on the Geotail spacecraft

    International Nuclear Information System (INIS)

    Schmidt, R.; Arends, H.; Pedersen, A.

    1995-01-01

    A low and actively controlled electrostatic potential on the outer surfaces of a scientific spacecraft is very important for accurate measurements of cold plasma electrons and ions and the DC to low-frequency electric field. The Japanese/NASA Geotail spacecraft carriers as part of its scientific payload a novel ion emitter for active control of the electrostatic potential on the surface of the spacecraft. The aim of the ion emitter is to reduce the positive surface potential which is normally encountered in the outer magnetosphere when the spacecraft is sunlit. Ion emission clamps the surface potential to near the ambient plasma potential. Without emission control, Geotail has encountered plasma conditions in the lobes of the magnetotail which resulted in surface potentials of up to about +70 V. The ion emitter proves to be able to discharge the outer surfaces of the spacecraft and is capable of keeping the surface potential stable at about +2 V. This potential is measured with respect to one of the electric field probes which are current biased and thus kept at a potential slightly above the ambient plasma potential. The instrument uses the liquid metal field ion emission principle to emit indium ions. The ion beam energy is about 6 keV and the typical total emission current amounts to about 15 μA. Neither variations in the ambient plasma conditions nor operation of two electron emitters on Geotail produce significant variations of the controlled surface potential as long as the resulting electron emission currents remain much smaller than the ion emission current. Typical results of the active potential control are shown, demonstrating the surface potential reduction and its stability over time. 25 refs., 5 figs

  13. Submarines, spacecraft and exhaled breath.

    Science.gov (United States)

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    extend the underwater endurance to 2-3 weeks. These propulsion engineering changes also reduce periodic ventilation of the submarine's interior and thus put a greater burden on the various maintenance systems. We note that the spaceflight community has similar issues; their energy production mechanisms are essentially air independent in that they rely almost entirely on photovoltaic arrays for electricity generation, with only emergency back-up power from alcohol fuel cells. In response to prolonged underwater submarine AIP operations, months-long spaceflight operations onboard the ISS and planning for future years-long missions to Mars, there has been an increasing awareness that bio-monitoring is an important factor for assessing the health and awareness states of the crewmembers. SAMAP researchers have been proposing various air and bio-monitoring instruments and methods in response to these needs. One of the most promising new methodologies is the non-invasive monitoring of exhaled breath. So, what do the IABR and SAMAP communities have in common? Inhalation toxicology. We are both concerned with contamination from the environment, either as a direct health threat or as a confounder for diagnostic assessments. For example, the exhaled breath from subjects in a contaminated and enclosed artificial environment (submarine or spacecraft) can serve as a model system and a source of contamination for their peers in a cleaner environment. In a similar way, exhaled anaesthetics can serve as a source of contamination in hospital/clinical settings, or exhalation of occupational exposures to tetrachloroethylene can impact family members at home. Instrumentation development. Both communities have similar needs for better, more specific and more sensitive instruments. Certainly, the analytical instruments to be used onboard submarines and spacecraft have severe restrictions on energy use, physical size and ease of operation. The medical and clinical communities have similar long

  14. Construction of special eye models for investigation of chromatic and higher-order aberrations of eyes.

    Science.gov (United States)

    Zhai, Yi; Wang, Yan; Wang, Zhaoqi; Liu, Yongji; Zhang, Lin; He, Yuanqing; Chang, Shengjiang

    2014-01-01

    An achromatic element eliminating only longitudinal chromatic aberration (LCA) while maintaining transverse chromatic aberration (TCA) is established for the eye model, which involves the angle formed by the visual and optical axis. To investigate the impacts of higher-order aberrations on vision, the actual data of higher-order aberrations of human eyes with three typical levels are introduced into the eye model along visual axis. Moreover, three kinds of individual eye models are established to investigate the impacts of higher-order aberrations, chromatic aberration (LCA+TCA), LCA and TCA on vision under the photopic condition, respectively. Results show that for most human eyes, the impact of chromatic aberration on vision is much stronger than that of higher-order aberrations, and the impact of LCA in chromatic aberration dominates. The impact of TCA is approximately equal to that of normal level higher-order aberrations and it can be ignored when LCA exists.

  15. Specialist report : Dry eye disease and aging

    NARCIS (Netherlands)

    van Tilborg, M.M.A.; Kort, H.S.M.; Murphy, P.J.

    2017-01-01

    The common ocular pathologies relating to the aging eye, such as cataract, diabetic retinopathy, glaucoma, or macular degeneration, are all known to reduce visual functioning. Less wellknown is the effect of common, age-related dry eye disease (DED). The impact of DED on daily activities can be

  16. Charging in the environment of large spacecraft

    International Nuclear Information System (INIS)

    Lai, S.T.

    1993-01-01

    This paper discusses some potential problems of spacecraft charging as a result of interactions between a large spacecraft, such as the Space Station, and its environment. Induced electric field, due to VXB effect, may be important for large spacecraft at low earth orbits. Differential charging, due to different properties of surface materials, may be significant when the spacecraft is partly in sunshine and partly in shadow. Triple-root potential jump condition may occur because of differential charging. Sudden onset of severe differential charging may occur when an electron or ion beam is emitted from the spacecraft. The beam may partially return to the ''hot spots'' on the spacecraft. Wake effects, due to blocking of ambient ion trajectories, may result in an undesirable negative potential region in the vicinity of a large spacecraft. Outgassing and exhaust may form a significant spacecraft induced environment; ionization may occur. Spacecraft charging and discharging may affect the electronic components on board

  17. Collie eye anomaly: a review

    Czech Academy of Sciences Publication Activity Database

    Palánová, Anna

    2015-01-01

    Roč. 60, č. 7 (2015), s. 345-350 ISSN 0375-8427 R&D Projects: GA MŠk ED2.1.00/03.0124 Institutional support: RVO:67985904 Keywords : hereditary * eye * disease * dog Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 0.560, year: 2015

  18. The Impact of Perceived Hospital Service Quality on the Satisfaction and Patients' Return; A Case Study in Feiz Medical Eye Center

    Directory of Open Access Journals (Sweden)

    Mahmud Naderi Beni

    2018-03-01

    Full Text Available Background and Objectives: Nowadays, with the appearance of competitive environment, quality of services is important. The sector of health has a special status compared with other sectors of services. Patients determine the quality of services that are provided by hospitals which are regarded as large and complex service organizations within the health system. The aim of this study was to investigate the relationship between perceived service quality, perceived services value, patients’ satisfaction, word of mouth advertising and tendency to patients’ return. Material and Methods: This study was a descriptive and functional and from aspect of results, is practical and was done by one cross-sectional and fieldwork. The sample of study of 135 health care receivers, who were referred at least once from Feiz eye clinic in Isfahan were selected by using Cochran formula and stratified with random sampling. The data collected with a questionnaire which its reliability and validity were confirmed. The collected data were analyzed with SPSS and Smart PLS2 software. Results: The findings showed that all indices have acceptable load factor. Perceived service quality had a significant positive impact on perceived value (0.57 and patient satisfaction (0.28. Perceived value had a significant positive effect on patients’ satisfaction and patients’ return. Also, patients’ satisfaction had effect on word of mouth advertising and word of mouth advertising had effect on the patients’ return. Conclusion: The results of the study indicated that perceived value and patients’ satisfaction meditate between the relationship of perceived service quality and patients’ return. In addition, the indirect effect of perceived value on patients’ return, with changeable mediation of patients’ satisfaction is more than direct effect. Also, among the variables, patients’ satisfaction had greatest effect on patients return.

  19. Coping with dry eyes: a qualitative approach.

    Science.gov (United States)

    Yeo, Sharon; Tong, Louis

    2018-01-16

    Dry eye is a common problem that affects many people worldwide, reducing quality of life and impacting daily activities. A qualitative approach often used in medicine and other disciplines is used to evaluate how people with dry eye cope with this impact. Six focus group sessions were conducted at the Singapore National Eye Centre (SNEC), premises of an eye research institute. These focus groups consist of a spectrum of dry eye sufferers (30 women, 8 men, aged 61 ± 11.8 years). Standard methods of coding followed by determination of themes were adhered to. Where classification was difficult, consensus was made between 3 assessors. Audio-recorded transcripts were coded in 10 themes by 3 assessors independently. Four of the themes involved traditional measures such as lid warming, cleansing, lubrication and oral dietary supplements. The other themes discovered were Traditional Chinese Medicine, modification of eye-care habits (e.g. wearing sunglasses), environmental humidity, lifestyle (e.g. sleeping habits), psychological attitude, and lastly sharing and communication. Holistic coping strategies were found to be prominent in dry eye sufferers from these focus groups, and people tend to find personalised ways of coping with the impact of dry eye on daily living.

  20. Quick Spacecraft Thermal Analysis Tool, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — For spacecraft design and development teams concerned with cost and schedule, the Quick Spacecraft Thermal Analysis Tool (QuickSTAT) is an innovative software suite...

  1. Multiple spacecraft Michelson stellar interferometer

    Science.gov (United States)

    Stachnik, R. V.; Arnold, D.; Melroy, P.; Mccormack, E. F.; Gezari, D. Y.

    1984-01-01

    Results of an orbital analysis and performance assessment of SAMSI (Spacecraft Array for Michelson Spatial Interferometry) are presented. The device considered includes two one-meter telescopes in orbits which are identical except for slightly different inclinations; the telescopes achieve separations as large as 10 km and relay starlight to a central station which has a one-meter optical delay line in one interferometer arm. It is shown that a 1000-km altitude, zero mean inclination orbit affords natural scanning of the 10-km baseline with departures from optical pathlength equality which are well within the corrective capacity of the optical delay line. Electric propulsion is completely adequate to provide the required spacecraft motions, principally those needed for repointing. Resolution of 0.00001 arcsec and magnitude limits of 15 to 20 are achievable.

  2. Spacecraft Tests of General Relativity

    Science.gov (United States)

    Anderson, John D.

    1997-01-01

    Current spacecraft tests of general relativity depend on coherent radio tracking referred to atomic frequency standards at the ground stations. This paper addresses the possibility of improved tests using essentially the current system, but with the added possibility of a space-borne atomic clock. Outside of the obvious measurement of the gravitational frequency shift of the spacecraft clock, a successor to the suborbital flight of a Scout D rocket in 1976 (GP-A Project), other metric tests would benefit most directly by a possible improved sensitivity for the reduced coherent data. For purposes of illustration, two possible missions are discussed. The first is a highly eccentric Earth orbiter, and the second a solar-conjunction experiment to measure the Shapiro time delay using coherent Doppler data instead of the conventional ranging modulation.

  3. Attitude Fusion Techniques for Spacecraft

    DEFF Research Database (Denmark)

    Bjarnø, Jonas Bækby

    Spacecraft platform instability constitutes one of the most significant limiting factors in hyperacuity pointing and tracking applications, yet the demand for accurate, timely and reliable attitude information is ever increasing. The PhD research project described within this dissertation has...... served to investigate the solution space for augmenting the DTU μASC stellar reference sensor with a miniature Inertial Reference Unit (IRU), thereby obtaining improved bandwidth, accuracy and overall operational robustness of the fused instrument. Present day attitude determination requirements are met...... of the instrument, and affecting operations during agile and complex spacecraft attitude maneuvers. As such, there exists a theoretical foundation for augmenting the high frequency performance of the μASC instrument, by harnessing the complementary nature of optical stellar reference and inertial sensor technology...

  4. Autonomous spacecraft rendezvous and docking

    Science.gov (United States)

    Tietz, J. C.; Almand, B. J.

    A storyboard display is presented which summarizes work done recently in design and simulation of autonomous video rendezvous and docking systems for spacecraft. This display includes: photographs of the simulation hardware, plots of chase vehicle trajectories from simulations, pictures of the docking aid including image processing interpretations, and drawings of the control system strategy. Viewgraph-style sheets on the display bulletin board summarize the simulation objectives, benefits, special considerations, approach, and results.

  5. Nonlinearity-induced spacecraft tumbling

    International Nuclear Information System (INIS)

    Amos, A.K.

    1994-01-01

    An existing tumbling criterion for the dumbbell satellite in planar librations is reexamined and modified to reflect a recently identified tumbling mode associated with the horizontal attitude orientation. It is shown that for any initial attitude there exists a critical angular rate below which the motion is oscillatory and harmonic and beyond which a continuous tumbling will ensue. If the angular rate is at the critical value the spacecraft drifts towards the horizontal attitude from which a spontaneous periodic tumbling occurs

  6. Worldwide Spacecraft Crew Hatch History

    Science.gov (United States)

    Johnson, Gary

    2009-01-01

    The JSC Flight Safety Office has developed this compilation of historical information on spacecraft crew hatches to assist the Safety Tech Authority in the evaluation and analysis of worldwide spacecraft crew hatch design and performance. The document is prepared by SAIC s Gary Johnson, former NASA JSC S&MA Associate Director for Technical. Mr. Johnson s previous experience brings expert knowledge to assess the relevancy of data presented. He has experience with six (6) of the NASA spacecraft programs that are covered in this document: Apollo; Skylab; Apollo Soyuz Test Project (ASTP), Space Shuttle, ISS and the Shuttle/Mir Program. Mr. Johnson is also intimately familiar with the JSC Design and Procedures Standard, JPR 8080.5, having been one of its original developers. The observations and findings are presented first by country and organized within each country section by program in chronological order of emergence. A host of reference sources used to augment the personal observations and comments of the author are named within the text and/or listed in the reference section of this document. Careful attention to the selection and inclusion of photos, drawings and diagrams is used to give visual association and clarity to the topic areas examined.

  7. Integrating standard operating procedures with spacecraft automation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft automation has the potential to assist crew members and spacecraft operators in managing spacecraft systems during extended space missions. Automation can...

  8. Spacecraft TT&C and information transmission theory and technologies

    CERN Document Server

    Liu, Jiaxing

    2015-01-01

    Spacecraft TT&C and Information Transmission Theory and Technologies introduces the basic theory of spacecraft TT&C (telemetry, track and command) and information transmission. Combining TT&C and information transmission, the book presents several technologies for continuous wave radar including measurements for range, range rate and angle, analog and digital information transmissions, telecommand, telemetry, remote sensing and spread spectrum TT&C. For special problems occurred in the channels for TT&C and information transmission, the book represents radio propagation features and its impact on orbit measurement accuracy, and the effects caused by rain attenuation, atmospheric attenuation and multi-path effect, and polarization composition technology. This book can benefit researchers and engineers in the field of spacecraft TT&C and communication systems. Liu Jiaxing is a professor at The 10th Institute of China Electronics Technology Group Corporation.

  9. A Shaftless Magnetically Levitated Multifunctional Spacecraft Flywheel Storage System

    Science.gov (United States)

    Stevens, Ken; Thornton, Richard; Clark, Tracy; Beaman, Bob G.; Dennehy, Neil; Day, John H. (Technical Monitor)

    2002-01-01

    Presently many types of spacecraft use a Spacecraft Attitude Control System (ACS) with momentum wheels for steering and electrochemical batteries to provide electrical power for the eclipse period of the spacecraft orbit. Future spacecraft will use Flywheels for combined use in ACS and Energy Storage. This can be done by using multiple wheels and varying the differential speed for ACS and varying the average speed for energy storage and recovery. Technology in these areas has improved since the 1990s so it is now feasible for flywheel systems to emerge from the laboratory for spacecraft use. This paper describes a new flywheel system that can be used for both ACS and energy storage. Some of the possible advantages of a flywheel system are: lower total mass and volume, higher efficiency, less thermal impact, improved satellite integration schedule and complexity, simplified satellite orbital operations, longer life with lower risk, less pointing jitter, and greater capability for high-rate slews. In short, they have the potential to enable new types of missions and provide lower cost. Two basic types of flywheel configurations are the Flywheel Energy Storage System (FESS) and the Integrated Power and Attitude Control System (IPACS).

  10. Deep Space Networking Experiments on the EPOXI Spacecraft

    Science.gov (United States)

    Jones, Ross M.

    2011-01-01

    NASA's Space Communications & Navigation Program within the Space Operations Directorate is operating a program to develop and deploy Disruption Tolerant Networking [DTN] technology for a wide variety of mission types by the end of 2011. DTN is an enabling element of the Interplanetary Internet where terrestrial networking protocols are generally unsuitable because they rely on timely and continuous end-to-end delivery of data and acknowledgments. In fall of 2008 and 2009 and 2011 the Jet Propulsion Laboratory installed and tested essential elements of DTN technology on the Deep Impact spacecraft. These experiments, called Deep Impact Network Experiment (DINET 1) were performed in close cooperation with the EPOXI project which has responsibility for the spacecraft. The DINET 1 software was installed on the backup software partition on the backup flight computer for DINET 1. For DINET 1, the spacecraft was at a distance of about 15 million miles (24 million kilometers) from Earth. During DINET 1 300 images were transmitted from the JPL nodes to the spacecraft. Then, they were automatically forwarded from the spacecraft back to the JPL nodes, exercising DTN's bundle origination, transmission, acquisition, dynamic route computation, congestion control, prioritization, custody transfer, and automatic retransmission procedures, both on the spacecraft and on the ground, over a period of 27 days. The first DINET 1 experiment successfully validated many of the essential elements of the DTN protocols. DINET 2 demonstrated: 1) additional DTN functionality, 2) automated certain tasks which were manually implemented in DINET 1 and 3) installed the ION SW on nodes outside of JPL. DINET 3 plans to: 1) upgrade the LTP convergence-layer adapter to conform to the international LTP CL specification, 2) add convergence-layer "stewardship" procedures and 3) add the BSP security elements [PIB & PCB]. This paper describes the planning and execution of the flight experiment and the

  11. Interventions for disorders of eye movement in patients with stroke

    OpenAIRE

    Pollock, A.; Hazelton, C.; Henderson, C.A.; Angilley, J.; Dhillon, B.; Langhorne, P.; Livingstone, K.; Munro, F.A.; Orr, H.; Rowe, F.J.; Shahani, U.

    2011-01-01

    Background Eye movement disorders may affect over 70% of stroke patients. These eye movement disorders can result in difficulty maintaining the normal ocular position and difficulty moving the eyes appropriately. The resulting functional disabilities include a loss of depth perception, reduced hand-to-eye co-ordination, marked difficulties with near tasks and reading and reduced ability to scan the visual environment. They can also impact on the effectiveness of rehabilitation therapy. There ...

  12. External eye symptoms in indoor environments.

    Science.gov (United States)

    Wolkoff, P

    2017-03-01

    Eye irritation, for example dry or irritated eyes, is generally among top three reported symptoms in office-like environments, in particular among workplaces with cognitive demanding visual display unit (VDU) work. The symptoms are especially among middle and advanced ages and particularly among women more than men. The symptoms are also among the most commonly reported complaints in the eye clinic. To be in a position to interpret the high prevalence of eye symptoms, a multidisciplinary and integrated approach is necessary that involves the external eye physiology (separate from internal eye effects), eye diseases (evaporative dry eye (DE), aqueous-deficient DE, and gland dysfunctions), and risk factors that aggravate the stability of precorneal tear film (PTF) resulting in hyperosmolarity and initiation of inflammatory reactions. Indoor environmental, occupational and personal risk factors may aggravate the PTF stability; factors such as age, contact lenses, cosmetics, diet, draft, gender, low humidity and high temperature, medication, outdoor and combustion pollutants, and VDU work. Psychological stressors may further influence the reporting behavior of eye symptoms. The impact of the risk factors may occur in a combined and exacerbating manner. © 2016 The Authors. Indoor Air published by John Wiley & Sons Ltd.

  13. Spacecraft Jitter Attenuation Using Embedded Piezoelectric Actuators

    Science.gov (United States)

    Belvin, W. Keith

    1995-01-01

    Remote sensing from spacecraft requires precise pointing of measurement devices in order to achieve adequate spatial resolution. Unfortunately, various spacecraft disturbances induce vibrational jitter in the remote sensing instruments. The NASA Langley Research Center has performed analysis, simulations, and ground tests to identify the more promising technologies for minimizing spacecraft pointing jitter. These studies have shown that the use of smart materials to reduce spacecraft jitter is an excellent match between a maturing technology and an operational need. This paper describes the use of embedding piezoelectric actuators for vibration control and payload isolation. In addition, recent advances in modeling, simulation, and testing of spacecraft pointing jitter are discussed.

  14. Dry eyes : a commonly missed eye condition

    OpenAIRE

    Vella, Mario;

    2014-01-01

    Tears are an important component in providing moisture and lubrication for the eyes, thereby maintaining vision and comfort. Dry eyes (keratoconjunctivitis sicca) result when there is either decreased production of tears or by poor tear quality which in turn lead to more rapid evaporation.

  15. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Kierstan Boyd Reviewed By: Brenda Pagan-Duran MD Sep. 01, 2017 Our eyes need tears to stay ... tear duct to insert a permanent punctal plug? Sep 12, 2017 Why are my eyes bloodshot when ...

  16. What Is Dry Eye?

    Medline Plus

    Full Text Available ... seasonal allergens and dry eye Apr 27, 2015 Choosing Wisely When It Comes to Eye Care, Part ... Name: Member ID: * Phone Number: * Email: * Enter code: * Message: Thank you Your feedback has been sent.

  17. About the Eye

    Medline Plus

    Full Text Available ... Disease Education Program Glaucoma Education Program Low Vision Education Program ... Eye Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety ...

  18. Pink Eye (Conjunctivitis)

    Science.gov (United States)

    ... or child care if you're not able to take time off — just stay consistent in practicing good hygiene. Preventing pink eye in newborns Newborns' eyes are susceptible to bacteria normally present in the mother's birth canal. ...

  19. About the Eye

    Medline Plus

    Full Text Available ... Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety ... much as it does on your eyes. ... of Health | USA.gov NIH…Turning Discovery Into Health ®

  20. About the Eye

    Medline Plus

    Full Text Available ... Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the ...

  1. Preventing Eye Injuries

    Science.gov (United States)

    ... Your Eyes Sep 20, 2017 Eye Injuries from Laundry Packets On the Rise Jun 30, 2017 ... Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American ...

  2. About the Eye

    Medline Plus

    Full Text Available ... National Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, ...

  3. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Eye Health Home Annual Meeting Clinical Education Practice Management Member Services Advocacy Foundation About Subspecialties & More Academy Publications EyeNet Ophthalmology Ophthalmology Retina Information for: International Ophthalmologists Media Medical Students Patients and ...

  4. What Is Dry Eye?

    Medline Plus

    Full Text Available ... right type of tears or tear film . How do tears work? When you blink, a film of ... layer cleans the eye, washing away particles that do not belong in the eye. This layer comes ...

  5. About the Eye

    Medline Plus

    Full Text Available ... The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid ... Your eyes are made up of many different parts that work together to help you see. Check out the ...

  6. About the Eye

    Medline Plus

    Full Text Available ... Vision Education Program Hispanic/Latino Program Vision and Aging Program African American Program Training and Jobs Fellowships ... Defenses Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear Sports and Your Eyes ...

  7. About the Eye

    Medline Plus

    Full Text Available ... Clinical Director Laboratories, Sections and Units Division of Epidemiology and Clinical Applications eyeGENE Research Directors Office Office ... Diabetic Eye Disease Education Program Glaucoma Education Program Low Vision Education Program Hispanic/Latino Program Vision and ...

  8. About the Eye

    Medline Plus

    Full Text Available ... Home » NEI for Kids » About the Eye Listen All About Vision About the Eye Ask a Scientist ... you can see and make sense of the world around you. Did You Know? Vision depends on ...

  9. About the Eye

    Medline Plus

    Full Text Available ... search for current job openings visit HHS USAJobs Home >> NEI for Kids >> About the Eye Listen All ... much as it does on your eyes. NEI Home Contact Us A-Z Site Map NEI on ...

  10. About the Eye

    Medline Plus

    Full Text Available ... NIH), the National Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of ...

  11. Eye Involvement in TSC

    Science.gov (United States)

    ... eye involvement. Nonretinal and Retinal Eye Findings Facial angiofibromas may involve the eyelids of individuals with TSC, ... the hamartomas have many blood vessels (as are angiofibromas of the skin). Less than half of the ...

  12. What Is Dry Eye?

    Medline Plus

    Full Text Available ... removed or pushed down the tear duct to insert a permanent punctal plug? Sep 12, 2017 Why ... Eye from Jennifer Aniston Sep 02, 2016 The link between seasonal allergens and dry eye Apr 27, ...

  13. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Services Advocacy Foundation About Subspecialties & More Eye Health Home Annual Meeting Clinical Education Practice Management Member Services Advocacy Foundation About Subspecialties & More Academy Publications EyeNet ...

  14. About the Eye

    Medline Plus

    Full Text Available ... First Aid Tips Healthy Vision Tips Protective Eyewear Sports and Your Eyes Fun Stuff Cool Eye Tricks ... website is maintained by the NEI Office of Science Communications, Public Liaison, and Education. Technical questions about ...

  15. About the Eye

    Medline Plus

    Full Text Available ... search for current job openings visit HHS USAJobs Home » NEI for Kids » About the Eye Listen All ... much as it does on your eyes. NEI Home Contact Us A-Z Site Map NEI on ...

  16. About the Eye

    Medline Plus

    Full Text Available ... the special health problems and requirements of the blind.” News & Events Events Calendar NEI Press Releases News ... First Aid Tips Healthy Vision Tips Protective Eyewear Sports and Your Eyes Fun Stuff Cool Eye Tricks ...

  17. The impact of x-ray tube configuration on the eye lens and extremity doses received by cardiologists in electrophysiology room

    International Nuclear Information System (INIS)

    Domienik, J; Zmyślony, M; Bissinger, A

    2014-01-01

    The aim of the study was to analyse the influence of the x-ray tube configuration on the radiation doses to eye lens and extremities of cardiologists performing pacemaker implantation procedures in electrophysiology laboratory. The measurements were performed on one, widely used, portable C-arm system, first with x-ray tube mounted above the patient table and image intensifier below it and then on a reinstalled (but essentially the same) system with under-table x-ray tube configuration. Thermoluminescent dosimeters, placed in various positions near the eye lens, on the hands and ankle, were used during every procedure. The comparison of doses received by cardiologists after changing the x-ray tube configuration from over- to under-table shows statistically significant dose reduction (p < 0.009) for the eye lens closest to the x-ray tube, left finger, left wrist, while for the ankle a dose increase is observed. The corresponding over- to under-table x-ray tube median dose ratios are 4.1 for the right eye, 4.8 for the left finger, 3.0 for left wrist and, finally, 0.13 for the right ankle. Systems with under-table x-ray tube are preferable from a radiation protection point of view. The observed significant increase in doses to the legs should be partially compensated by the use of a protective lead curtain. (note)

  18. Impact of nest predators, competitors, and ectoparasites on Pearly-eyed Thrashers, with comments on the potential implications for Puerto Rican Parrot recovery

    Science.gov (United States)

    Wayne J. Arendt

    2000-01-01

    Over the past 17 years, research on a rain forest population of the Pearly-eyed Thrasher (Margarops fuscatus), with additional observations on nesting Puerto Rican Parrots (Amazona vittata) within the Sierra de Luquillo, Puerto Rico, has shown that reproductive success of thrashers and parrots is often greatly reduced as a result of the additive effects of a diverse...

  19. Immunology of the eye

    OpenAIRE

    Weronika Ratajczak; Beata Tokarz-Deptuła; Wiesław Deptuła

    2018-01-01

    The eye is an organ of sight characterized by unusual immunological properties, resulting from its anatomical structure and physiology, as well as the presence of specific elements that, through the mechanisms of innate and adaptive immunity, provide homeostasis of the eyeball. This article reviews the defensive elements of individual eye structures: conjunctiva, cornea, lacrimal gland, anterior chamber of the eye, uvea, retina and eye-associated lymphoid tissue (EALT), where we distinguish a...

  20. Spacecraft Design Thermal Control Subsystem

    Science.gov (United States)

    Miyake, Robert N.

    2008-01-01

    The Thermal Control Subsystem engineers task is to maintain the temperature of all spacecraft components, subsystems, and the total flight system within specified limits for all flight modes from launch to end-of-mission. In some cases, specific stability and gradient temperature limits will be imposed on flight system elements. The Thermal Control Subsystem of "normal" flight systems, the mass, power, control, and sensing systems mass and power requirements are below 10% of the total flight system resources. In general the thermal control subsystem engineer is involved in all other flight subsystem designs.

  1. The all seeing eye?

    NARCIS (Netherlands)

    Koenderink, Jan J.

    2014-01-01

    The All Seeing Eye? Did you know that you are probably a believer in the All Seeing Eye? The odds are that I’m right—why? Well, the bulk of mainstream vision literature blindly relies on the All Seeing Eye. It is written all over papers, albeit between the lines. Understandably so, for scientists

  2. About the Eye

    Medline Plus

    Full Text Available ... other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health ... Eye Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and ...

  3. Dwarf Eye Disorder

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    Johns Hopkins researchers at the Wilmer Eye Institute have discovered what appears to be the first human gene mutation that causes extreme farsightedness. The researchers report that nanophthalmos, Greek for "dwarf eye," is a rare, potentially blinding disorder caused by an alteration in a gene called MFRP that helps control eye growth and…

  4. Fish eye optics

    Science.gov (United States)

    Hudec, R.; Michalova, S.

    2017-07-01

    We report on small student (high—school) project of the Czech Academy of Sciences dealing with animal (fish) eyes and possible application in science and technology. Albeit most fishes have refractive eyes, the recent discoveries confirm that some fishes have reflective eyes with strange arrangements as well.

  5. Eye and orbital cavity

    International Nuclear Information System (INIS)

    Panfilova, G.V.; Koval', G.Yu.

    1984-01-01

    Radioanatomy of eyes and orbit is described. Diseases of the orbit (developmental anomalies, inflammatory diseases, lacrimal apparatus deseases, toxoplasmosis, tumors and cysts et al.), methods of foreign body localization in the eye are considered. Roentgenograms of the orbit and calculation table for foreign body localization in spherical eyes of dissimilar diameter are presented

  6. Recognizing and Treating Eye Injuries

    Science.gov (United States)

    ... Eye Injuries First Aid for Eye Scratches Protective Eyewear Children’s Eye Injuries: Prevention and Care Eye Injuries ... Academy Jobs at the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For ...

  7. [Macroeconomic costs of eye diseases].

    Science.gov (United States)

    Hirneiß, C; Kampik, A; Neubauer, A S

    2014-05-01

    Eye diseases that are relevant regarding their macroeconomic costs and their impact on society include cataract, diabetic retinopathy, age-related maculopathy, glaucoma and refractive errors. The aim of this article is to provide a comprehensive overview of direct and indirect costs for major eye disease categories for Germany, based on existing literature and data sources. A semi-structured literature search was performed in the databases Medline and Embase and in the search machine Google for relevant original papers and reviews on costs of eye diseases with relevance for or transferability to Germany (last research date October 2013). In addition, manual searching was performed in important national databases and information sources, such as the Federal Office of Statistics and scientific societies. The direct costs for these diseases add up to approximately 2.6 billion Euros yearly for the Federal Republic of Germany, including out of the pocket payments from patients but excluding optical aids (e.g. glasses). In addition to those direct costs there are also indirect costs which are caused e.g. by loss of employment or productivity or by a reduction in health-related quality of life. These indirect costs can only be roughly estimated. Including the indirect costs for the eye diseases investigated, a total yearly macroeconomic cost ranging between 4 and 12 billion Euros is estimated for Germany. The costs for the eye diseases cataract, diabetic retinopathy, age-related maculopathy, glaucoma and refractive errors have a macroeconomic relevant dimension. Based on the predicted demographic changes with an ageing society an increase of the prevalence and thus also an increase of costs for eye diseases is expected in the future.

  8. Benefits of Spacecraft Level Vibration Testing

    Science.gov (United States)

    Gordon, Scott; Kern, Dennis L.

    2015-01-01

    NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

  9. Hybrid spacecraft attitude control system

    Directory of Open Access Journals (Sweden)

    Renuganth Varatharajoo

    2016-02-01

    Full Text Available The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.

  10. EYE GAZE TRACKING

    DEFF Research Database (Denmark)

    2017-01-01

    This invention relates to a method of performing eye gaze tracking of at least one eye of a user, by determining the position of the center of the eye, said method comprising the steps of: detecting the position of at least three reflections on said eye, transforming said positions to spanning...... a normalized coordinate system spanning a frame of reference, wherein said transformation is performed based on a bilinear transformation or a non linear transformation e.g. a möbius transformation or a homographic transformation, detecting the position of said center of the eye relative to the position...... of said reflections and transforming this position to said normalized coordinate system, tracking the eye gaze by tracking the movement of said eye in said normalized coordinate system. Thereby calibration of a camera, such as knowledge of the exact position and zoom level of the camera, is avoided...

  11. Estimating Torque Imparted on Spacecraft Using Telemetry

    Science.gov (United States)

    Lee, Allan Y.; Wang, Eric K.; Macala, Glenn A.

    2013-01-01

    There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.

  12. Optimal Autonomous Spacecraft Resiliency Maneuvers Using Metaheuristics

    Science.gov (United States)

    2014-09-15

    This work was accepted for published by the American Institute of Aeronautics and Astronautics (AIAA) Journal of Spacecraft and Rockets in July 2014...publication in the AIAA Journal of Spacecraft and Rockets . Chapter 5 introduces an impulsive maneuvering strategy to deliver a spacecraft to its final...upon arrival r2 and v2 , respectively. The variable T2 determines the time of flight needed to make the maneuver, and the variable θ2 determines the

  13. Eye contact and Cross-cultural Communication

    Institute of Scientific and Technical Information of China (English)

    刘西娟

    2009-01-01

    It is commonly agreed by contemporary schohrs that it is important to understand the role of culture and its characteristics and potential impact on individuals engaged in cross-cultural communication.Nonverbal Communication often reveals basic culture traits.Eye contact,as a mediunq to convey emodon.attitudes and intention.phys an undeniably vital role in communication.The concentration of this paper is to discuss the functions of eye contact in communication,different information conveyed by eve contact on the basis of different cultures and the importance of understanding and respecting the rituals of eye contact in cross-culmral communication.

  14. Radiation effects on eye components

    International Nuclear Information System (INIS)

    Durchschlag, H.; Fochler, C.; Abraham, K.; Kulawik, B.

    1998-01-01

    The radiation damage (X-ray, UV light) of the most important components of the vertebrate eye (crystallins and other proteins, hyaluronic acid, vitreous, aqueous humour, ascorbic acid) has been investigated by various methods of physical chemistry. UV absorption and fluorescence spectroscopy as well as circular dichroism unveiled changes of the chromophores/fluorophores of the constituent biopolymers and low-molecular components, together with alterations of helix content and the occurrence of aggregation. Size-exclusion chromatography, analytical ultracentrifugation, densimetry, viscometry and light scattering experiments monitored changes of the global structure of proteins and polysaccharides involved. Electrophoreses allowed conclusions on fragmentation, unfolding and crosslinking. Analytical methods provided information regarding the integrity of groups of special concern (SH, SS) and revealed the existence of stable noxious species (H 2 O 2 ). By means of various measures and additives, manifold modifications of the impact of both ionizing and nonionizing radiation may be achieved. Caused by differences in the primary reactions, eye polymers are protected efficaciously by typical OH radical scavengers against X-irradiation, whereas compounds which exhibit absorption behavior in the UV range turn out to act as potent protectives ('chemical filters') against UV light. A few substances, such as ascorbate, are able to provide protection against both sorts of radiation and are even able to exhibit a slight chemical repair of already damaged particles. The results obtained are of importance for understanding pathological alterations of the eye (loss of transparency, cataractogenesis) and for developing new strategies for protection and repair of eye components. (author)

  15. Eye surgery in the elderly

    Directory of Open Access Journals (Sweden)

    Raczyńska D

    2016-04-01

    Full Text Available Dorota Raczyńska, Leopold Glasner, Ewelina Serkies-Minuth, Magdalena A Wujtewicz, Kamila Mitrosz Department of Ophthalmology, Medical University of Gdansk, Gdansk, Poland Abstract: Extending life expectancy is a human achievement. It does however entail problems. Ophthalmic treatments are widely recognized as having a low risk of general complications. A classic example is cataract surgery, considered to be one of the safest and most frequently performed surgical procedures in the world. However, advanced age brings with it risks that should be considered before surgery. Eye operations, as with procedures on other organs, are largely dependent on the quality of surgical tissues. Therefore, the elderly are at increased risk of complications. Improved general health and postoperative follow-up with the use of noninvasive technologies such as optical coherence tomography translate into lower intraoperative risk and better postoperative prognosis. In this review, we discuss the impact of general health on operational prognosis, therapeutic problems, and technical difficulties which a surgeon and anesthesiologist may encounter in the process. We also consider new technology and strategies specifically aimed at treating eye conditions in the elderly. Keywords: eye surgery, eye aging, anesthesiology in ophthalmology, cataract, glaucoma, vitrectomy, age-related macular degeneration

  16. Ulysses spacecraft control and monitoring system

    Science.gov (United States)

    Hamer, P. A.; Snowden, P. J.

    1991-01-01

    The baseline Ulysses spacecraft control and monitoring system (SCMS) concepts and the converted SCMS, residing on a DEC/VAX 8350 hardware, are considered. The main functions of the system include monitoring and displaying spacecraft telemetry, preparing spacecraft commands, producing hard copies of experimental data, and archiving spacecraft telemetry. The SCMS system comprises over 20 subsystems ranging from low-level utility routines to the major monitoring and control software. These in total consist of approximately 55,000 lines of FORTRAN source code and 100 VMS command files. The SCMS major software facilities are described, including database files, telemetry processing, telecommanding, archiving of data, and display of telemetry.

  17. Operationally Responsive Spacecraft Subsystem, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Saber Astronautics proposes spacecraft subsystem control software which can autonomously reconfigure avionics for best performance during various mission conditions....

  18. Organization of eye bank

    International Nuclear Information System (INIS)

    Reddy, S.C.

    1999-01-01

    Comeal transplantation is the only method of combating the blindness due to corneal opacity caused by infections, malnutrition, trauma and hereditary diseases. Comeal blindness is more prevalent in the developing countries. The availability of the donor cornea, trained ophthalmic surgeons and microsurgery facilities are the key factors in restoring vision in-patients with comeal blindness. The eye bank organization is somewhat similar to that of blood bank. The eye bank should be located in a hospital or a medical centre in which a laboratory may be established for the evaluation and storage of donor tissue. The medical director (Ophthalmologist), technician, secretary and public relation officer are the persons who play an important role in the successful organization of eye bank. The function of the eye bank are procurement, assessment, processing, distribution of donor eyes/corneas, training of technicians/doctors, and conducting research related to storage of donor tissue and corneal transplantation. The necessary infrastructure required for the organization of an eye bank include separate accommodation area for the personnel and the laboratory, telephone, computer, refrigerator, laminar air flow hood. Slitlamp, specular microscope, storage media and equipment, instrument for enucleation of donor eyes, and a motor vehicle. The details of responsibilities of the staff of eye bank, source of donor eyes, suitability of donor material, procurement of the donor cornea, tissue assessment, storage and preservation, distribution of donor tissue, and limitation of eye bank will be discussed at the time of presentation

  19. EyeMusic: Making Music with the Eyes

    OpenAIRE

    Hornof, Anthony J.; Sato, Linda

    2004-01-01

    Though musical performers routinely use eye movements to communicate with each other during musical performances, very few performers or composers have used eye tracking devices to direct musical compositions and performances. EyeMusic is a system that uses eye movements as an input to electronic music compositions. The eye movements can directly control the music, or the music can respond to the eyes moving around a visual scene. EyeMusic is implemented so that any composer using established...

  20. Eye Disease and Development

    DEFF Research Database (Denmark)

    Andersen, Thomas Barnebeck; Dalgaard, Carl-Johan Lars; Selaya, Pablo

    This research advances the hypothesis that cross-country variation in the historical incidence of eye disease has influenced the current global distribution of per capita income. The theory is that pervasive eye disease diminished the incentive to accumulate skills, thereby delaying the fertility...... transition and the take-off to sustained economic growth. In order to estimate the influence from eye disease incidence empirically, we draw on an important fact from the field of epidemiology: Exposure to solar ultraviolet B radiation (UVB-R) is an underlying determinant of several forms of eye disease...

  1. Inflammation in dry eye.

    Science.gov (United States)

    Stern, Michael E; Pflugfelder, Stephen C

    2004-04-01

    Dry eye is a condition of altered tear composition that results from a diseased or dysfunctional lacrimal functional unit. Evidence suggests that inflammation causes structural alterations and/or functional paralysis of the tear-secreting glands. Changes in tear composition resulting from lacrimal dysfunction, increased evaporation and/or poor clearance have pro-inflammatory effects on the ocular surface. This inflammation is responsible in part for the irritation symptoms, ocular surface epithelial disease, and altered corneal epithelial barrier function in dry eye. Anti-inflammatory therapies for dry eye target one or more of the inflammatory mediators/pathways that have been identified in dry eye.

  2. LASIK eye surgery

    Science.gov (United States)

    ... Assisted In Situ Keratomileusis; Laser vision correction; Nearsightedness - Lasik; Myopia - Lasik ... cornea (curvature) and the length of the eye. LASIK uses an excimer laser (an ultraviolet laser) to ...

  3. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics ... Services Advocacy Foundation About Subspecialties & More Eye ...

  4. Prevention of Eye Injuries

    OpenAIRE

    Pashby, Tom

    1981-01-01

    In Canada 30,000 people are registered as blind; in one third of these, blindness might have been avoided. Prevention is the key to reducing the number of eye injuries and blind eyes. The role of the family physician in early identification of treatable conditions and in the education of patients is discussed, but responsibility for prevention belongs to all physicians. The success of prevention is seen in the great reduction in eye injuries in industry and sports since eye protectors have be...

  5. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Academy Publications EyeNet Ophthalmology ...

  6. Spacecraft command and control using expert systems

    Science.gov (United States)

    Norcross, Scott; Grieser, William H.

    1994-01-01

    This paper describes a product called the Intelligent Mission Toolkit (IMT), which was created to meet the changing demands of the spacecraft command and control market. IMT is a command and control system built upon an expert system. Its primary functions are to send commands to the spacecraft and process telemetry data received from the spacecraft. It also controls the ground equipment used to support the system, such as encryption gear, and telemetry front-end equipment. Add-on modules allow IMT to control antennas and antenna interface equipment. The design philosophy for IMT is to utilize available commercial products wherever possible. IMT utilizes Gensym's G2 Real-time Expert System as the core of the system. G2 is responsible for overall system control, spacecraft commanding control, and spacecraft telemetry analysis and display. Other commercial products incorporated into IMT include the SYBASE relational database management system and Loral Test and Integration Systems' System 500 for telemetry front-end processing.

  7. Modelling human eye under blast loading.

    Science.gov (United States)

    Esposito, L; Clemente, C; Bonora, N; Rossi, T

    2015-01-01

    Primary blast injury (PBI) is the general term that refers to injuries resulting from the mere interaction of a blast wave with the body. Although few instances of primary ocular blast injury, without a concomitant secondary blast injury from debris, are documented, some experimental studies demonstrate its occurrence. In order to investigate PBI to the eye, a finite element model of the human eye using simple constitutive models was developed. The material parameters were calibrated by a multi-objective optimisation performed on available eye impact test data. The behaviour of the human eye and the dynamics of mechanisms occurring under PBI loading conditions were modelled. For the generation of the blast waves, different combinations of explosive (trinitrotoluene) mass charge and distance from the eye were analysed. An interpretation of the resulting pressure, based on the propagation and reflection of the waves inside the eye bulb and orbit, is proposed. The peculiar geometry of the bony orbit (similar to a frustum cone) can induce a resonance cavity effect and generate a pressure standing wave potentially hurtful for eye tissues.

  8. Temperature control of the Mariner class spacecraft - A seven mission summary.

    Science.gov (United States)

    Dumas, L. N.

    1973-01-01

    Mariner spacecraft have completed five missions of scientific investigation of the planets. Two additional missions are planned. A description of the thermal design of these seven spacecraft is given herein. The factors which have influenced the thermal design include the mission requirements and constraints, the flight environment, certain programmatic considerations and the experience gained as each mission is completed. These factors are reviewed and the impact of each on thermal design and developmental techniques is assessed. It is concluded that the flight success of these spacecraft indicates that adequate temperature control has been obtained, but that improvements in design data, hardware performance and analytical techniques are needed.

  9. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Ophthalmologists Young Ophthalmologists Tools and Services EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and Deadlines ... Ophthalmologists Young Ophthalmologists Tools and Services EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and Deadlines ...

  10. Eye tracking social preferences

    NARCIS (Netherlands)

    Jiang, Ting; Potters, Jan; Funaki, Yukihiko

    We hypothesize that if people are motivated by a particular social preference, then choosing in accordance with this preference will lead to an identifiable pattern of eye movements. We track eye movements while subjects make choices in simple three-person distribution experiments. We characterize

  11. XI. THE WATERING EYE

    African Journals Online (AJOL)

    cause a watering eye; this condition is.called epiphora. Clearly, then, in investigating ... blockage is a common disease in the middle age-groups seen in hospital .... a dry eye, and this is so much worse than a wet one that the procedure is only ...

  12. Dry eye syndrome

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000426.htm Dry eye syndrome To use the sharing features on this page, ... second-hand smoke exposure Cold or allergy medicines Dry eye can also be caused by: Heat or ... Symptoms may include: Blurred vision Burning, itching, ...

  13. What Is Dry Eye?

    Medline Plus

    Full Text Available ... is also when your eyes do not make the right type of tears or tear film . How do tears work? When you blink, a film of tears spreads over the eye. This keeps the eye’s surface smooth and ...

  14. Photorefraction of the Eye

    Science.gov (United States)

    Colicchia, Giuseppe; Wiesner, Hartmut; Zollman, Dean

    2015-01-01

    Photorefraction is a method to easily estimate the refractive state of the eye. The principle of photorefraction involves projecting light into the eye during flash photography and then examining the paths of light that emerge from the pupil after scattering on the back portion of the interior of the eyeball (fundus). We will explain the optical…

  15. Lasik eye surgery - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100206.htm Lasik eye surgery - series—Normal anatomy To use the ... A.M. Editorial team. Related MedlinePlus Health Topics Laser Eye Surgery A.D.A.M., Inc. is accredited by ...

  16. About the Eye

    Medline Plus

    Full Text Available ... luh) is the small, sensitive area of the retina needed for central vision. It contains the fovea. Lens is the clear part of the eye behind the iris that helps to focus light on the retina. It allows the eye to focus on both ...

  17. LASIK Eye Surgery

    Science.gov (United States)

    ... at the front of your eye — to improve vision. Normally, images are clearly focused on the retina in the back of your eye because the ... sharply, light rays focus in front of the retina and blur distant vision. You can see objects that are close fairly ...

  18. About the Eye

    Medline Plus

    Full Text Available ... NIH), the National Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and ...

  19. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Services EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and Deadlines Museum of Vision Ophthalmology Job ... Services EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and Deadlines Museum of Vision Ophthalmology Job ...

  20. What Is Dry Eye?

    Medline Plus

    Full Text Available ... also when your eyes do not make the right type of tears or tear film . How do tears work? When you blink, a film of tears spreads over the eye. This keeps the eye’s surface smooth and clear. The tear film is important for good vision. The tear film is made of three ...

  1. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Medicare Physician Payment Meetings and Deadlines Museum of Vision Ophthalmology Job Center Our Sites EyeWiki International Society ... Medicare Physician Payment Meetings and Deadlines Museum of Vision Ophthalmology Job Center Our Sites EyeWiki International Society ...

  2. Smoking and Eye Health

    Science.gov (United States)

    ... Patient Stories Español Eye Health / Tips & Prevention Sections Smoking and Eye Disease Leer en Español: El cigarrillo ... By: Brenda Pagan-Duran MD Apr. 27, 2017 Smoking contributes to a number of major health problems, ...

  3. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Payment Meetings and Deadlines Museum of Vision Ophthalmology Job Center Our Sites EyeWiki International Society of Refractive ... Payment Meetings and Deadlines Museum of Vision Ophthalmology Job Center Our Sites EyeWiki International Society of Refractive ...

  4. About the Eye

    Medline Plus

    Full Text Available ... Learn how the different parts of your eye work together so you can see and make sense of the world around you. Did You Know? Vision depends on your brain as much as it does on your eyes. NEI Home Contact Us A-Z Site Map NEI on ...

  5. What Is Dry Eye?

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    Full Text Available ... Media Medical Students Patients and Public Technicians and Nurses Senior Ophthalmologists Young Ophthalmologists Tools and Services EyeCare ... Media Medical Students Patients and Public Technicians and Nurses Senior Ophthalmologists Young Ophthalmologists Tools and Services EyeCare ...

  6. BullsEye

    DEFF Research Database (Denmark)

    Klokmose, Clemens Nylandsted; Kristensen, Janus Bager; Bagge, Rolf

    2014-01-01

    implemented primarily in shaders on the GPU. The techniques are realized in the BullsEye computer vision software. We demonstrate experimentally that BullsEye provides sub-pixel accuracy down to a tenth of a pixel, which is a significant improvement compared to the commonly used reacTIVision software....

  7. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Young Ophthalmologists Tools and Services EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and Deadlines Museum ... Young Ophthalmologists Tools and Services EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and Deadlines Museum ...

  8. What Is Dry Eye?

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    Full Text Available ... Senior Ophthalmologists Young Ophthalmologists Tools and Services EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and ... Senior Ophthalmologists Young Ophthalmologists Tools and Services EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and ...

  9. What Is Dry Eye?

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    Full Text Available ... Public Technicians and Nurses Senior Ophthalmologists Young Ophthalmologists Tools and Services EyeCare America Help IRIS Registry Medicare ... Public Technicians and Nurses Senior Ophthalmologists Young Ophthalmologists Tools and Services EyeCare America Help IRIS Registry Medicare ...

  10. What Is Dry Eye?

    Medline Plus

    Full Text Available ... bloodshot when I wake up? Jun 26, 2016 Why are my eyes dry after LASIK? Jun 19, 2016 Can I be tested whether I close my eyes when I sleep? Feb 10, 2016 Can light sensitivity from Parkinson’s ...

  11. Apoptosis in the eye.

    OpenAIRE

    Chahory , Sabine; Torriglia , Alicia

    2006-01-01

    Apoptosis is a normal component of the development and health of multicellular organisms. Cells die during apoptosis in a controlled, regulated fashion. This form of cell death is very important in eye development as well as in eye pathology. We review in this chapter our current knowledge in this topic.

  12. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Medical Students Patients and Public Technicians and Nurses Senior Ophthalmologists Young Ophthalmologists Tools and Services EyeCare America ... Medical Students Patients and Public Technicians and Nurses Senior Ophthalmologists Young Ophthalmologists Tools and Services EyeCare America ...

  13. Eyes, Bulging (Proptosis)

    Science.gov (United States)

    ... Early Breast Cancer to Avoid Chemo Could a Blood Test Spot Lung Cancer Early? Experimental Drug Shows 'Modest' Benefit ... often done when bulging affects only one eye. Blood tests to measure how well the thyroid is working are done when ... When bulging leads to severe dry eyes, lubrication with artificial tears is needed to ...

  14. Multi-objective optimisation for spacecraft design for demise and survivability

    OpenAIRE

    Trisolini, Mirko; Colombo, Camilla; Lewis, Hugh

    2017-01-01

    The paper presents the development of a multi-objective optimisation framework to study the effects that preliminary design choices have on the demisability and the survivability of a spacecraft. Building a spacecraft such that most of it will demise during the re-entry through design-for-demise strategies may lead to design that are more vulnerable to space debris impacts, thus compromising the reliability of the mission. The two models developed to analyse the demisability and the survivabi...

  15. Printable Spacecraft: Flexible Electronic Platforms for NASA Missions. Phase One

    Science.gov (United States)

    Short, Kendra (Principal Investigator); Van Buren, David (Principal Investigator)

    2012-01-01

    Atmospheric confetti. Inchworm crawlers. Blankets of ground penetrating radar. These are some of the unique mission concepts which could be enabled by a printable spacecraft. Printed electronics technology offers enormous potential to transform the way NASA builds spacecraft. A printed spacecraft's low mass, volume and cost offer dramatic potential impacts to many missions. Network missions could increase from a few discrete measurements to tens of thousands of platforms improving areal density and system reliability. Printed platforms could be added to any prime mission as a low-cost, minimum resource secondary payload to augment the science return. For a small fraction of the mass and cost of a traditional lander, a Europa flagship mission might carry experimental printed surface platforms. An Enceladus Explorer could carry feather-light printed platforms to release into volcanic plumes to measure composition and impact energies. The ability to print circuits directly onto a variety of surfaces, opens the possibility of multi-functional structures and membranes such as "smart" solar sails and balloons. The inherent flexibility of a printed platform allows for in-situ re-configurability for aerodynamic control or mobility. Engineering telemetry of wheel/soil interactions are possible with a conformal printed sensor tape fit around a rover wheel. Environmental time history within a sample return canister could be recorded with a printed sensor array that fits flush to the interior of the canister. Phase One of the NIAC task entitled "Printable Spacecraft" investigated the viability of printed electronics technologies for creating multi-functional spacecraft platforms. Mission concepts and architectures that could be enhanced or enabled with this technology were explored. This final report captures the results and conclusions of the Phase One study. First, the report presents the approach taken in conducting the study and a mapping of results against the proposed

  16. Implementation of Organ Culture storage of donor corneas: a 3 year study of its impact on the corneal transplant wait list at the Lions New South Wales Eye Bank.

    Science.gov (United States)

    Devasahayam, Raj; Georges, Pierre; Hodge, Christopher; Treloggen, Jane; Cooper, Simon; Petsoglou, Con; Sutton, Gerard; Zhu, Meidong

    2016-09-01

    Organ Culture corneal storage offers an extended storage time and increased donor pool and tissue assessment opportunities. In September 2011, the Lions New South Wales Eye Bank (LNSWEB) moved from hypothermic storage to Organ Culture corneal storage. This study evaluates the impact of implementation of Organ Culture on donor eye retrieval and the corneal transplant waiting list over a 3 year period in NSW, Australia. Retrospective review of the LNSWEB data from September 2011 to August 2014. Tissue collection, waiting list and tissue utilization data were recorded. The data from September 2008 to August 2011 for Optisol-GS storage was used for comparison. The annual donor and cornea collection rate increased 35 % and 44 % respectively with Organ Culture compared to Optisol-GS storage. The utilization rate of corneal tissue increased from 73.4 % with hypothermic storage to 77.2 % with Organ Culture storage. The transplant wait list decreased by 77.3 % from September 2011 to August 2014 and correlated with the increased rate of corneal transplantation (r = -0.9381, p banks. The practical benefits of the extended storage time and increased donor assessment opportunities have directly led to an increase in corneal utilization rate and a significant decrease in recipient wait list time.

  17. NASA Spacecraft Fault Management Workshop Results

    Science.gov (United States)

    Newhouse, Marilyn; McDougal, John; Barley, Bryan; Fesq, Lorraine; Stephens, Karen

    2010-01-01

    Fault Management is a critical aspect of deep-space missions. For the purposes of this paper, fault management is defined as the ability of a system to detect, isolate, and mitigate events that impact, or have the potential to impact, nominal mission operations. The fault management capabilities are commonly distributed across flight and ground subsystems, impacting hardware, software, and mission operations designs. The National Aeronautics and Space Administration (NASA) Discovery & New Frontiers (D&NF) Program Office at Marshall Space Flight Center (MSFC) recently studied cost overruns and schedule delays for 5 missions. The goal was to identify the underlying causes for the overruns and delays, and to develop practical mitigations to assist the D&NF projects in identifying potential risks and controlling the associated impacts to proposed mission costs and schedules. The study found that 4 out of the 5 missions studied had significant overruns due to underestimating the complexity and support requirements for fault management. As a result of this and other recent experiences, the NASA Science Mission Directorate (SMD) Planetary Science Division (PSD) commissioned a workshop to bring together invited participants across government, industry, academia to assess the state of the art in fault management practice and research, identify current and potential issues, and make recommendations for addressing these issues. The workshop was held in New Orleans in April of 2008. The workshop concluded that fault management is not being limited by technology, but rather by a lack of emphasis and discipline in both the engineering and programmatic dimensions. Some of the areas cited in the findings include different, conflicting, and changing institutional goals and risk postures; unclear ownership of end-to-end fault management engineering; inadequate understanding of the impact of mission-level requirements on fault management complexity; and practices, processes, and

  18. Impact of Anodal and Cathodal Transcranial Direct Current Stimulation over the Left Dorsolateral Prefrontal Cortex during Attention Bias Modification: An Eye-Tracking Study.

    Directory of Open Access Journals (Sweden)

    Alexandre Heeren

    Full Text Available People with anxiety disorders show an attentional bias for threat (AB, and Attention Bias Modification (ABM procedures have been found to reduce this bias. However, the underlying processes accounting for this effect remain poorly understood. One explanation suggests that ABM requires the modification of attention control, driven by the recruitment of the dorsolateral prefrontal cortex (DLPFC. In the present double-blind study, we examined whether modifying left DLPFC activation influences the effect of ABM on AB. We used transcranial direct current stimulation (tDCS to directly modulate cortical excitability of the left DLPFC during an ABM procedure designed to reduce AB to threat. Anodal tDCS increases excitability, whereas cathodal tDCS decreases it. We randomly assigned highly trait-anxious individuals to one of three conditions: 1 ABM combined with cathodal tDCS, 2 ABM combined with anodal tDCS, or 3 ABM combined with sham tDCS. We assessed the effects of these manipulations on both reaction times and eye-movements on a task indexing AB. Results indicate that combining ABM and anodal tDCS over the left DLPFC reduces the total duration that participants' gaze remains fixated on threat, as assessed using eye-tracking measurement. However, in contrast to previous studies, there were no changes in AB from baseline to post-training for participants that received ABM without tDCS. As the tendency to maintain attention to threat is known to play an important role in the maintenance of anxiety, the present findings suggest that anodal tDCS over the left DLPFC may be considered as a promising tool to reduce the maintenance of gaze to threat. Implications for future translational research combining ABM and tDCS are discussed.

  19. Foot Pedals for Spacecraft Manual Control

    Science.gov (United States)

    Love, Stanley G.; Morin, Lee M.; McCabe, Mary

    2010-01-01

    Fifty years ago, NASA decided that the cockpit controls in spacecraft should be like the ones in airplanes. But controls based on the stick and rudder may not be best way to manually control a vehicle in space. A different method is based on submersible vehicles controlled with foot pedals. A new pilot can learn the sub's control scheme in minutes and drive it hands-free. We are building a pair of foot pedals for spacecraft control, and will test them in a spacecraft flight simulator.

  20. Advocacy for eye care

    Directory of Open Access Journals (Sweden)

    Thulasiraj D Ravilla

    2012-01-01

    Full Text Available The effectiveness of eye care service delivery is often dependant on how the different stakeholders are aligned. These stakeholders range from the ministries of health who have the capacity to grant government subsidies for eye care, down to the primary healthcare workers who can be enrolled to screen for basic eye diseases. Advocacy is a tool that can help service providers draw the attention of key stakeholders to a particular area of concern. By enlisting the support, endorsement and participation of a wider circle of players, advocacy can help to improve the penetration and effectiveness of the services provided. There are several factors in the external environmental that influence the eye care services - such as the availability of trained manpower, supply of eye care consumables, government rules and regulations. There are several instances where successful advocacy has helped to create an enabling environment for eye care service delivery. Providing eye care services in developing countries requires the support - either for direct patient care or for support services such as producing trained manpower or for research and dissemination. Such support, in the form of financial or other resources, can be garnered through advocacy.

  1. Aquaporins in the Eye

    DEFF Research Database (Denmark)

    Tran, Thuy Linh; Hamann, Steffen; Heegaard, Steffen

    2017-01-01

    The major part of the eye consists of water . Continuous movement of water and ions between the ocular compartments and to the systemic circulation is pivotal for many physiological functions in the eye. The movement of water facilitates removal of the many metabolic products of corneal-, ciliary...... pressure. In the retina, water is transported into the vitreous body and across the retinal pigment epithelium to regulate the extracellular environment and the hydration of the retina. Aquaporins (AQPs ) take part in the water transport throughout the eye....

  2. Distributed Autonomous Control of Multiple Spacecraft During Close Proximity Operations

    National Research Council Canada - National Science Library

    McCamish, Shawn B

    2007-01-01

    This research contributes to multiple spacecraft control by developing an autonomous distributed control algorithm for close proximity operations of multiple spacecraft systems, including rendezvous...

  3. Spacecraft Swarm Coordination and Planning Tool, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Fractionated spacecraft architectures to distribute mission performance from a single, monolithic satellite across large number of smaller spacecraft, for missions...

  4. Spacecraft Cabin Particulate Monitor, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We have built and tested an optical extinction monitor for the detection of spacecraft cabin particulates. This sensor sensitive to particle sizes ranging from a few...

  5. SSTI- Lewis Spacecraft Nickel-Hydrogen Battery

    Science.gov (United States)

    Tobias, R. F.

    1997-01-01

    Topics considered include: NASA-Small Spacecraft Technology Initiative (SSTI) objectives, SSTI-Lewis overview, battery requirement, two cells Common Pressure Vessel (CPV) design summary, CPV electric performance, battery design summary, battery functional description, battery performance.

  6. Spacecraft Cabin Particulate Monitor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design, build and test an optical extinction monitor for the detection of spacecraft cabin particulates. This monitor will be sensitive to particle...

  7. Automated constraint checking of spacecraft command sequences

    Science.gov (United States)

    Horvath, Joan C.; Alkalaj, Leon J.; Schneider, Karl M.; Spitale, Joseph M.; Le, Dang

    1995-01-01

    Robotic spacecraft are controlled by onboard sets of commands called "sequences." Determining that sequences will have the desired effect on the spacecraft can be expensive in terms of both labor and computer coding time, with different particular costs for different types of spacecraft. Specification languages and appropriate user interface to the languages can be used to make the most effective use of engineering validation time. This paper describes one specification and verification environment ("SAVE") designed for validating that command sequences have not violated any flight rules. This SAVE system was subsequently adapted for flight use on the TOPEX/Poseidon spacecraft. The relationship of this work to rule-based artificial intelligence and to other specification techniques is discussed, as well as the issues that arise in the transfer of technology from a research prototype to a full flight system.

  8. Computational Model for Spacecraft/Habitat Volume

    Data.gov (United States)

    National Aeronautics and Space Administration — Please note that funding to Dr. Simon Hsiang, a critical co-investigator for the development of the Spacecraft Optimization Layout and Volume (SOLV) model, was...

  9. Industry perspectives on Plug-& -Play Spacecraft Avionics

    Science.gov (United States)

    Franck, R.; Graven, P.; Liptak, L.

    This paper describes the methodologies and findings from an industry survey of awareness and utility of Spacecraft Plug-& -Play Avionics (SPA). The survey was conducted via interviews, in-person and teleconference, with spacecraft prime contractors and suppliers. It focuses primarily on AFRL's SPA technology development activities but also explores the broader applicability and utility of Plug-& -Play (PnP) architectures for spacecraft. Interviews include large and small suppliers as well as large and small spacecraft prime contractors. Through these “ product marketing” interviews, awareness and attitudes can be assessed, key technical and market barriers can be identified, and opportunities for improvement can be uncovered. Although this effort focuses on a high-level assessment, similar processes can be used to develop business cases and economic models which may be necessary to support investment decisions.

  10. Spacecraft Multiple Array Communication System Performance Analysis

    Science.gov (United States)

    Hwu, Shian U.; Desilva, Kanishka; Sham, Catherine C.

    2010-01-01

    The Communication Systems Simulation Laboratory (CSSL) at the NASA Johnson Space Center is tasked to perform spacecraft and ground network communication system simulations, design validation, and performance verification. The CSSL has developed simulation tools that model spacecraft communication systems and the space and ground environment in which the tools operate. In this paper, a spacecraft communication system with multiple arrays is simulated. Multiple array combined technique is used to increase the radio frequency coverage and data rate performance. The technique is to achieve phase coherence among the phased arrays to combine the signals at the targeting receiver constructively. There are many technical challenges in spacecraft integration with a high transmit power communication system. The array combining technique can improve the communication system data rate and coverage performances without increasing the system transmit power requirements. Example simulation results indicate significant performance improvement can be achieved with phase coherence implementation.

  11. Formation of disintegration particles in spacecraft recorders

    International Nuclear Information System (INIS)

    Kurnosova, L.V.; Fradkin, M.I.; Razorenov, L.A.

    1986-01-01

    Experiments performed on the spacecraft Salyut 1, Kosmos 410, and Kosmos 443 enable us to record the disintegration products of particles which are formed in the material of the detectors on board the spacecraft. The observations were made by means of a delayed coincidence method. We have detected a meson component and also a component which is apparently associated with the generation of radioactive isotopes in the detectors

  12. Power requirements for commercial communications spacecraft

    Science.gov (United States)

    Billerbeck, W. J.

    1985-01-01

    Historical data on commercial spacecraft power systems are presented and their power requirements to the growth of satellite communications channel usage are related. Some approaches for estimating future power requirements of this class of spacecraft through the year 2000 are proposed. The key technology drivers in satellite power systems are addressed. Several technological trends in such systems are described, focusing on the most useful areas for research and development of major subsystems, including solar arrays, energy storage, and power electronics equipment.

  13. A Reconfigurable Testbed Environment for Spacecraft Autonomy

    Science.gov (United States)

    Biesiadecki, Jeffrey; Jain, Abhinandan

    1996-01-01

    A key goal of NASA's New Millennium Program is the development of technology for increased spacecraft on-board autonomy. Achievement of this objective requires the development of a new class of ground-based automony testbeds that can enable the low-cost and rapid design, test, and integration of the spacecraft autonomy software. This paper describes the development of an Autonomy Testbed Environment (ATBE) for the NMP Deep Space I comet/asteroid rendezvous mission.

  14. Radiation Effects on Spacecraft Structural Materials

    International Nuclear Information System (INIS)

    Wang, Jy-An J.; Ellis, Ronald J.; Hunter, Hamilton T.; Singleterry, Robert C. Jr.

    2002-01-01

    Research is being conducted to develop an integrated technology for the prediction of aging behavior for space structural materials during service. This research will utilize state-of-the-art radiation experimental apparatus and analysis, updated codes and databases, and integrated mechanical and radiation testing techniques to investigate the suitability of numerous current and potential spacecraft structural materials. Also included are the effects on structural materials in surface modules and planetary landing craft, with or without fission power supplies. Spacecraft structural materials would also be in hostile radiation environments on the surface of the moon and planets without appreciable atmospheres and moons around planets with large intense magnetic and radiation fields (such as the Jovian moons). The effects of extreme temperature cycles in such locations compounds the effects of radiation on structural materials. This paper describes the integrated methodology in detail and shows that it will provide a significant technological advance for designing advanced spacecraft. This methodology will also allow for the development of advanced spacecraft materials through the understanding of the underlying mechanisms of material degradation in the space radiation environment. Thus, this technology holds a promise for revolutionary advances in material damage prediction and protection of space structural components as, for example, in the development of guidelines for managing surveillance programs regarding the integrity of spacecraft components, and the safety of the aging spacecraft. (authors)

  15. Standardizing the information architecture for spacecraft operations

    Science.gov (United States)

    Easton, C. R.

    1994-01-01

    This paper presents an information architecture developed for the Space Station Freedom as a model from which to derive an information architecture standard for advanced spacecraft. The information architecture provides a way of making information available across a program, and among programs, assuming that the information will be in a variety of local formats, structures and representations. It provides a format that can be expanded to define all of the physical and logical elements that make up a program, add definitions as required, and import definitions from prior programs to a new program. It allows a spacecraft and its control center to work in different representations and formats, with the potential for supporting existing spacecraft from new control centers. It supports a common view of data and control of all spacecraft, regardless of their own internal view of their data and control characteristics, and of their communications standards, protocols and formats. This information architecture is central to standardizing spacecraft operations, in that it provides a basis for information transfer and translation, such that diverse spacecraft can be monitored and controlled in a common way.

  16. Attitude Estimation in Fractionated Spacecraft Cluster Systems

    Science.gov (United States)

    Hadaegh, Fred Y.; Blackmore, James C.

    2011-01-01

    An attitude estimation was examined in fractioned free-flying spacecraft. Instead of a single, monolithic spacecraft, a fractionated free-flying spacecraft uses multiple spacecraft modules. These modules are connected only through wireless communication links and, potentially, wireless power links. The key advantage of this concept is the ability to respond to uncertainty. For example, if a single spacecraft module in the cluster fails, a new one can be launched at a lower cost and risk than would be incurred with onorbit servicing or replacement of the monolithic spacecraft. In order to create such a system, however, it is essential to know what the navigation capabilities of the fractionated system are as a function of the capabilities of the individual modules, and to have an algorithm that can perform estimation of the attitudes and relative positions of the modules with fractionated sensing capabilities. Looking specifically at fractionated attitude estimation with startrackers and optical relative attitude sensors, a set of mathematical tools has been developed that specify the set of sensors necessary to ensure that the attitude of the entire cluster ( cluster attitude ) can be observed. Also developed was a navigation filter that can estimate the cluster attitude if these conditions are satisfied. Each module in the cluster may have either a startracker, a relative attitude sensor, or both. An extended Kalman filter can be used to estimate the attitude of all modules. A range of estimation performances can be achieved depending on the sensors used and the topology of the sensing network.

  17. About the Eye

    Medline Plus

    Full Text Available ... programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and ... It sends electrical impulses through the optic nerve to the brain. Watch ...

  18. Diabetic Eye Problems

    Science.gov (United States)

    ... damage your eyes. The most common problem is diabetic retinopathy. It is a leading cause of blindness ... You need a healthy retina to see clearly. Diabetic retinopathy damages the tiny blood vessels inside your ...

  19. About the Eye

    Medline Plus

    Full Text Available ... of many different parts that work together to help you see. Check out the diagrams below to ... part of the eye behind the iris that helps to focus light on the retina. It allows ...

  20. About the Eye

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    Full Text Available ... to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and requirements of the blind.” ... Clinical Studies Publications Catalog Photos ...

  1. About the Eye

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    Full Text Available ... Stuff Cool Eye Tricks Links to More Information Optical Illusions Printables ... Optic nerve (OP-tic nurv) is the bundle of more than 1 million nerve fibers that carry visual messages from the retina to ...

  2. What Is Dry Eye?

    Medline Plus

    Full Text Available ... month dissolvable punctal plug be removed or pushed down the tear duct to insert a permanent punctal ... Your Eyelid Nov 29, 2017 New Dry Eye Treatment is a Tear-Jerker Jul 21, 2017 Three ...

  3. About the Eye

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    Full Text Available ... the Scientific Director Office of the Clinical Director Laboratories, Sections and Units Division of Epidemiology and Clinical ... System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear ...

  4. Eye Involvement in TSC

    Science.gov (United States)

    ... 50% of the individuals with TSC have normal intelligence, and inasmuch as these individuals may become parents, ... of vision may be difficult or impossible. Since growth and change of TSC lesions in the eye ...

  5. What Is Dry Eye?

    Medline Plus

    Full Text Available ... EyeCare America Help IRIS Registry Medicare Physician Payment Meetings and Deadlines Museum of Vision Ophthalmology Job Center ... Ophthalmology Guide Find an Ophthalmologist Advanced Search Annual Meeting Clinical Education Practice Management Member Services Advocacy Foundation ...

  6. About the Eye

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    Full Text Available ... Units Division of Epidemiology and Clinical Applications eyeGENE Research Directors Office Office of the Scientific Director Sheldon S. ... Fellowships NEI Summer Intern Program Diversity In Vision Research & Ophthalmology (DIVRO) Student Training Programs To search for ...

  7. Amblyopia: Lazy Eye Treatment

    Science.gov (United States)

    ... with Myopia Aug 31, 2017 Eye Injuries from Laundry Packets On the Rise Jun 30, 2017 Combating ... with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American ...

  8. Amblyopia: Lazy Eye Diagnosis

    Science.gov (United States)

    ... with Myopia Aug 31, 2017 Eye Injuries from Laundry Packets On the Rise Jun 30, 2017 Combating ... with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American ...

  9. What Is Dry Eye?

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    Full Text Available ... Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Academy Publications EyeNet Ophthalmology ... Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Find an Ophthalmologist Advanced ...

  10. About the Eye

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    Full Text Available ... the NEI Website search NEI on Social Media | Search A-Z | en español | Text size S M L ... (WSAC) Board of Scientific Counselors National Advisory Eye Council (NAEC) Donating to ...

  11. About the Eye

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    Full Text Available ... The Visual System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision Tips ... addressed to the NEI Website Manager . Department of Health and Human Services | The National Institutes of Health | ...

  12. What Is Dry Eye?

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    Full Text Available ... of tears or tear film . How do tears work? When you blink, a film of tears spreads ... Get ophthalmologist-reviewed tips and information about eye health and preserving your vision. Privacy Policy Related Please ...

  13. What Is Dry Eye?

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    Full Text Available ... treated? Jan 28, 2016 Find an Ophthalmologist Advanced Search Ask an Ophthalmologist Browse Answers Free Newsletter Get ophthalmologist-reviewed tips and information about eye health and preserving your vision. Privacy ...

  14. About the Eye

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    Full Text Available ... Units Division of Epidemiology and Clinical Applications eyeGENE Research Directors Office Office of the Scientific Director Sheldon S. Miller, Ph.D., Scientific Director David ...

  15. About the Eye

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    Full Text Available ... Program Diversity In Vision Research & Ophthalmology (DIVRO) Student Training Programs ... Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear Sports and ...

  16. About the Eye

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    Full Text Available ... Contact Us Visiting the NIH Campus Mission Statement As part of the federal government’s National Institutes of ... Did You Know? Vision depends on your brain as much as it does on your eyes. NEI ...

  17. About the Eye

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    Full Text Available ... NEI Women Scientists Advisory Committee (WSAC) Board of Scientific Counselors National Advisory Eye Council (NAEC) Donating to ... for the media Pressroom Contacts Dustin Hays - Chief, Science Communication dustin.hays@nih.gov Kathryn DeMott, Media ...

  18. About the Eye

    Medline Plus

    Full Text Available ... about each part of your eye and what it does. Macula (MACK-yoo-luh) is the small, ... area of the retina needed for central vision. It contains the fovea. Lens is the clear part ...

  19. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Academy Publications EyeNet Ophthalmology Ophthalmology Retina Information for: International Ophthalmologists Media Medical Students Patients and Public Technicians and Nurses Senior Ophthalmologists Young Ophthalmologists Tools ...

  20. What Is Dry Eye?

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    Full Text Available ... Ophthalmology/Strabismus Ocular Pathology/Oncology Oculoplastics/Orbit Refractive Management/Intervention Retina/Vitreous Uveitis ... Eye Health A-Z Symptoms Glasses & Contacts Tips & ...

  1. About the Eye

    Medline Plus

    Full Text Available ... Office of the Scientific Director Office of the Clinical Director Laboratories, Sections and Units Division of Epidemiology and Clinical Applications eyeGENE Research Directors Office Office of the ...

  2. Using Eye Makeup

    Science.gov (United States)

    ... harmful chemicals. Before applying makeup, be sure your face and eyelids are very clean. Always apply makeup outside the lash line, away from the eye, to avoid blocking the oil glands of the upper or lower ...

  3. About the Eye

    Medline Plus

    Full Text Available ... Photos and Images Spanish Language Information Grants and Funding Extramural Research Division of Extramural Science Programs Division ... Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety ...

  4. About the Eye

    Medline Plus

    Full Text Available ... of visual function, preservation of sight, and the special health problems and requirements of the blind.” News & ... Emily Y. Chew, M.D., Deputy Clinical Director Education Programs National Eye Health Education Program (NEHEP) Diabetic ...

  5. About the Eye

    Medline Plus

    Full Text Available ... part of your eye and what it does. Macula (MACK-yoo-luh) is the small, sensitive area ... FOH-vee-uh) is the center of the macula, where your vision is sharpest. Optic nerve (OP- ...

  6. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Academy Publications EyeNet Ophthalmology Ophthalmology Retina Information for: International Ophthalmologists ...

  7. About the Eye

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    Full Text Available ... 5248 Health Information Frequently asked questions Clinical Studies Publications Catalog Photos and Images Spanish Language Information Grants ... Emily Y. Chew, M.D., Deputy Clinical Director Education Programs National Eye Health Education Program (NEHEP) Diabetic ...

  8. Eye and orbit ultrasound

    Science.gov (United States)

    ... Images Head and eye echoencephalogram References Coleman DJ, Silverman RH, Lloyd HO, Daly S. Evaluation of the posterior ... Vision Institute, La Jolla, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial ...

  9. About the Eye

    Medline Plus

    Full Text Available ... Office of the Clinical Director Laboratories, Sections and Units Division of Epidemiology and Clinical Applications eyeGENE Research ... iris adjusts the size of the pupil and controls the amount of light that can enter the ...

  10. About the Eye

    Medline Plus

    Full Text Available ... System Your Eyes’ Natural Defenses Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear ... Social Media Policies and Other Important Links NEI Employee Emergency Information NEI Intranet (Employees Only) *PDF files ...

  11. What Is Dry Eye?

    Medline Plus

    Full Text Available ... information about eye health and preserving your vision. Privacy Policy Related Please Don’t Shave the Inside ... the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media ...

  12. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Uveitis Focus On Pediatric Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global ... an Ophthalmologist Patient Stories Español Eye Health / ...

  13. What Is Dry Eye?

    Medline Plus

    Full Text Available ... of tears or tear film . How do tears work? When you blink, a film of tears spreads ... eyes don’t make enough tears or something affects one or more layers of the tear film. ...

  14. About the Eye

    Medline Plus

    Full Text Available ... Learn how the different parts of your eye work together so you can see and make sense of the world around you. ... Social Media Policies and Other Important Links NEI Employee Emergency Information ...

  15. About the Eye

    Medline Plus

    Full Text Available ... Campus Mission Statement As part of the federal government’s National Institutes of Health (NIH), the National Eye ... Publications Catalog Photos and Images Spanish Language Information Grants and Funding Extramural Research Division of Extramural Science ...

  16. About the Eye

    Medline Plus

    Full Text Available ... are made up of many different parts that work together to help you see. Check out the diagrams ... Learn how the different parts of your eye work together so you can see and make sense of ...

  17. Eye Injuries at Home

    Science.gov (United States)

    ... by the Numbers — Infographic Five Steps to Safer Champagne Celebrations Eye Injuries at Home Leer en Español: ... that can splatter hot grease or oil. Opening champagne bottles during a celebration. Drilling or hammering screws ...

  18. About the Eye

    Medline Plus

    Full Text Available ... are made up of many different parts that work together to help you see. Check out the ... Learn how the different parts of your eye work together so you can see and make sense ...

  19. What Is Dry Eye?

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    Full Text Available ... Eye Care, Part 5 Mar 19, 2013 Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs at the Academy Financial Relationships with Industry ...

  20. About the Eye

    Medline Plus

    Full Text Available ... History of the NEI NEI 50th Anniversary NEI Women Scientists Advisory Committee (WSAC) Board of Scientific Counselors ... Emily Y. Chew, M.D., Deputy Clinical Director Education Programs National Eye Health Education Program (NEHEP) Diabetic ...

  1. Multidisciplinary studies of the social, economic and political impact resulting from recent advances in satellite meteorology. Volume 6: Executive summary. [technological forecasting spacecraft control/attitude (inclination) -classical mechanics

    Science.gov (United States)

    1975-01-01

    An assessment of the technological impact of modern satellite weather forecasting for the United States is presented. Topics discussed are: (1) television broadcasting of weather; (2) agriculture (crop production); (3) water resources; (4) urban development; (5) recreation; and (6) transportation.

  2. Human eye localization using the modified Hough transform

    Czech Academy of Sciences Publication Activity Database

    Dobeš, M.; Martínek, J.; Skoupil, D.; Dobešová, Z.; Pospíšil, Jaroslav

    2006-01-01

    Roč. 117, - (2006), s. 468-473 ISSN 0030-4026 Institutional research plan: CEZ:AV0Z10100522 Keywords : human eye localization * modified Hough transform * eye iris and eyelid shape determination Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.585, year: 2006

  3. Danish Rural Eye Study

    DEFF Research Database (Denmark)

    Høeg, Tracy Beth; Ellervik, Christina; Buch, Helena

    2016-01-01

    , Danish Rural Eye Study (DRES). All DRES participants received a comprehensive general health examination preceding their eye examination, including measurement of best-corrected visual acuity (BCVA) for each eye, bilateral 45° retinal fundus photographs and further ophthalmological examination where...... indicated. RESULTS: Overall, 3826 of 3843 participants (99.6%) had bilateral visual acuity measurements. The overall frequency of VI (BCVA eye) was 0.4% (95% confidence interval, CI, 0.2-0.7%; n = 15) among all DRES participants, 0.6% (95% CI 0.3-1.0%; n = 15) among participants...... >50 years and 3.7% (95% CI 2.1-6.5%; n = 11) in participants >80 years. The primary causes of VI in the better-seeing eye were age-related macular degeneration (AMD) in 46.7% (7/15) and cataract in 26.7% (4/15). A total of 43.3% (n = 115) of participants >80 years were pseudophakic in one or both eyes...

  4. Global Precipitation Measurement (GPM) Spacecraft Lithium Ion Battery Micro-Cycling Investigation

    Science.gov (United States)

    Dakermanji, George; Lee, Leonine; Spitzer, Thomas

    2016-01-01

    The Global Precipitation Measurement (GPM) spacecraft was jointly developed by NASA and JAXA. It is a Low Earth Orbit (LEO) spacecraft launched on February 27, 2014. The power system is a Direct Energy Transfer (DET) system designed to support 1950 watts orbit average power. The batteries use SONY 18650HC cells and consist of three 8s by 84p batteries operated in parallel as a single battery. During instrument integration with the spacecraft, large current transients were observed in the battery. Investigation into the matter traced the cause to the Dual-Frequency Precipitation Radar (DPR) phased array radar which generates cyclical high rate current transients on the spacecraft power bus. The power system electronics interaction with these transients resulted in the current transients in the battery. An accelerated test program was developed to bound the effect, and to assess the impact to the mission.

  5. Large-Scale Spacecraft Fire Safety Tests

    Science.gov (United States)

    Urban, David; Ruff, Gary A.; Ferkul, Paul V.; Olson, Sandra; Fernandez-Pello, A. Carlos; T'ien, James S.; Torero, Jose L.; Cowlard, Adam J.; Rouvreau, Sebastien; Minster, Olivier; hide

    2014-01-01

    An international collaborative program is underway to address open issues in spacecraft fire safety. Because of limited access to long-term low-gravity conditions and the small volume generally allotted for these experiments, there have been relatively few experiments that directly study spacecraft fire safety under low-gravity conditions. Furthermore, none of these experiments have studied sample sizes and environment conditions typical of those expected in a spacecraft fire. The major constraint has been the size of the sample, with prior experiments limited to samples of the order of 10 cm in length and width or smaller. This lack of experimental data forces spacecraft designers to base their designs and safety precautions on 1-g understanding of flame spread, fire detection, and suppression. However, low-gravity combustion research has demonstrated substantial differences in flame behavior in low-gravity. This, combined with the differences caused by the confined spacecraft environment, necessitates practical scale spacecraft fire safety research to mitigate risks for future space missions. To address this issue, a large-scale spacecraft fire experiment is under development by NASA and an international team of investigators. This poster presents the objectives, status, and concept of this collaborative international project (Saffire). The project plan is to conduct fire safety experiments on three sequential flights of an unmanned ISS re-supply spacecraft (the Orbital Cygnus vehicle) after they have completed their delivery of cargo to the ISS and have begun their return journeys to earth. On two flights (Saffire-1 and Saffire-3), the experiment will consist of a flame spread test involving a meter-scale sample ignited in the pressurized volume of the spacecraft and allowed to burn to completion while measurements are made. On one of the flights (Saffire-2), 9 smaller (5 x 30 cm) samples will be tested to evaluate NASAs material flammability screening tests

  6. The effectiveness of eye-closure in repeated interviews

    OpenAIRE

    Vredeveldt, A.; Baddeley, A.D.; Hitch, G.J.

    2014-01-01

    Purpose Closing the eyes during recall can help witnesses remember more about a witnessed event. This study examined the effectiveness of eye-closure in a repeated recall paradigm with immediate free recall followed 1 week later by both free and cued recall. We examined whether eye-closure was more or less effective during the second free-recall attempt compared with the first, whether eye-closure during the first recall attempt had an impact on subsequent free- and cued-recall performance, a...

  7. Pink Eye: What To Do

    Centers for Disease Control (CDC) Podcasts

    In this podcast, CDC's Adam Cohen, MD, a pediatrician and parent, discusses conjunctivitis (pink eye), a common eye condition in children and adults. He reviews pink eye causes and treatment, suggestions on when to call or visit a doctor, and practical tips to prevent pink eye from spreading.

  8. REQUIREMENTS FOR IMAGE QUALITY OF EMERGENCY SPACECRAFTS

    Directory of Open Access Journals (Sweden)

    A. I. Altukhov

    2015-05-01

    Full Text Available The paper deals with the method for formation of quality requirements to the images of emergency spacecrafts. The images are obtained by means of remote sensing of near-earth space orbital deployment in the visible range. of electromagnetic radiation. The method is based on a joint taking into account conditions of space survey, characteristics of surveillance equipment, main design features of the observed spacecrafts and orbital inspection tasks. Method. Quality score is the predicted linear resolution image that gives the possibility to create a complete view of pictorial properties of the space image obtained by electro-optical system from the observing satellite. Formulation of requirements to the numerical value of this indicator is proposed to perform based on the properties of remote sensing system, forming images in the conditions of outer space, and the properties of the observed emergency spacecraft: dimensions, platform construction of the satellite, on-board equipment placement. For method implementation the authors have developed a predictive model of requirements to a linear resolution for images of emergency spacecrafts, making it possible to select the intervals of space shooting and get the satellite images required for quality interpretation. Main results. To verify the proposed model functionality we have carried out calculations of the numerical values for the linear resolution of the image, ensuring the successful task of determining the gross structural damage of the spacecrafts and identifying changes in their spatial orientation. As input data were used with dimensions and geometric primitives corresponding to the shape of deemed inspected spacecrafts: Resurs-P", "Canopus-B", "Electro-L". Numerical values of the linear resolution images have been obtained, ensuring the successful task solution for determining the gross structural damage of spacecrafts.

  9. Investigating the Impact of Cognitive Style on Multimedia Learners' Understanding and Visual Search Patterns: An Eye-Tracking Approach

    Science.gov (United States)

    Liu, Han-Chin

    2018-01-01

    Multimedia students' dependence on information from the outside world can have an impact on their ability to identify and locate information from multiple resources in learning environments and thereby affect the construction of mental models. Field dependence-independence has been used to assess the ability to extract essential information from…

  10. NASA's "Eyes" Focus on Education

    Science.gov (United States)

    Hussey, K.

    2016-12-01

    NASA's "Eyes on…" suite of products continues to grow in capability and popularity. The "Eyes on the Earth", "Eyes on the Solar System" and "Eyes on Exoplanets" real-time, 3D interactive visualization products have proven themselves as highly effective demonstration and communication tools for NASA's Earth and Space Science missions. This presentation will give a quick look at the latest updates to the "Eyes" suite plus what is being done to make them tools for STEM Education.

  11. [Eye contact effects: A therapeutic issue?

    Science.gov (United States)

    Baltazar, M; Conty, L

    2016-12-01

    The perception of a direct gaze - that is, of another individual's gaze directed at the observer that leads to eye contact - is known to influence a wide range of cognitive processes and behaviors. We stress that these effects mainly reflect positive impacts on human cognition and may thus be used as relevant tools for therapeutic purposes. In this review, we aim (1) to provide an exhaustive review of eye contact effects while discussing the limits of the dominant models used to explain these effects, (2) to illustrate the therapeutic potential of eye contact by targeting those pathologies that show both preserved gaze processing and deficits in one or several functions that are targeted by the eye contact effects, and (3) to propose concrete ways in which eye contact could be employed as a therapeutic tool. (1) We regroup the variety of eye contact effects into four categories, including memory effects, activation of prosocial behavior, positive appraisals of self and others and the enhancement of self-awareness. We emphasize that the models proposed to account for these effects have a poor predictive value and that further descriptions of these effects is needed. (2) We then emphasize that people with pathologies that affect memory, social behavior, and self and/or other appraisal, and self-awareness could benefit from eye contact effects. We focus on depression, autism and Alzheimer's disease to illustrate our proposal. To our knowledge, no anomaly of eye contact has been reported in depression. Patients suffering from Alzheimer disease, at the early and moderate stage, have been shown to maintain a normal amount of eye contact with their interlocutor. We take into account that autism is controversial regarding whether gaze processing is preserved or altered. In the first view, individuals are thought to elude or omit gazing at another's eyes while in the second, individuals are considered to not be able to process the gaze of others. We adopt the first stance

  12. Modeling the fundamental characteristics and processes of the spacecraft functioning

    Science.gov (United States)

    Bazhenov, V. I.; Osin, M. I.; Zakharov, Y. V.

    1986-01-01

    The fundamental aspects of modeling of spacecraft characteristics by using computing means are considered. Particular attention is devoted to the design studies, the description of physical appearance of the spacecraft, and simulated modeling of spacecraft systems. The fundamental questions of organizing the on-the-ground spacecraft testing and the methods of mathematical modeling were presented.

  13. Automating Trend Analysis for Spacecraft Constellations

    Science.gov (United States)

    Davis, George; Cooter, Miranda; Updike, Clark; Carey, Everett; Mackey, Jennifer; Rykowski, Timothy; Powers, Edward I. (Technical Monitor)

    2001-01-01

    Spacecraft trend analysis is a vital mission operations function performed by satellite controllers and engineers, who perform detailed analyses of engineering telemetry data to diagnose subsystem faults and to detect trends that may potentially lead to degraded subsystem performance or failure in the future. It is this latter function that is of greatest importance, for careful trending can often predict or detect events that may lead to a spacecraft's entry into safe-hold. Early prediction and detection of such events could result in the avoidance of, or rapid return to service from, spacecraft safing, which not only results in reduced recovery costs but also in a higher overall level of service for the satellite system. Contemporary spacecraft trending activities are manually intensive and are primarily performed diagnostically after a fault occurs, rather than proactively to predict its occurrence. They also tend to rely on information systems and software that are oudated when compared to current technologies. When coupled with the fact that flight operations teams often have limited resources, proactive trending opportunities are limited, and detailed trend analysis is often reserved for critical responses to safe holds or other on-orbit events such as maneuvers. While the contemporary trend analysis approach has sufficed for current single-spacecraft operations, it will be unfeasible for NASA's planned and proposed space science constellations. Missions such as the Dynamics, Reconnection and Configuration Observatory (DRACO), for example, are planning to launch as many as 100 'nanospacecraft' to form a homogenous constellation. A simple extrapolation of resources and manpower based on single-spacecraft operations suggests that trending for such a large spacecraft fleet will be unmanageable, unwieldy, and cost-prohibitive. It is therefore imperative that an approach to automating the spacecraft trend analysis function be studied, developed, and applied to

  14. Autologous serum eye drops for dry eye

    Science.gov (United States)

    Pan, Qing; Angelina, Adla; Marrone, Michael; Stark, Walter J; Akpek, Esen K

    2017-01-01

    Background Theoretically, autologous serum eye drops (AS) offer a potential advantage over traditional therapies on the assumption that AS not only serve as a lacrimal substitute to provide lubrication but contain other biochemical components that allow them to mimic natural tears more closely. Application of AS has gained popularity as second-line therapy for patients with dry eye. Published studies on this subject indicate that autologous serum could be an effective treatment for dry eye. Objectives We conducted this review to evaluate the efficacy and safety of AS given alone or in combination with artificial tears as compared with artificial tears alone, saline, placebo, or no treatment for adults with dry eye. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 5), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to July 2016), Embase (January 1980 to July 2016), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to July 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We also searched the Science Citation Index Expanded database (December 2016) and reference lists of included studies. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 5 July 2016. Selection criteria We included randomized controlled trials (RCTs) that compared AS versus artificial tears for treatment of adults with dry eye. Data collection and analysis Two review authors independently screened all titles and abstracts and assessed full-text reports of potentially eligible trials. Two review authors extracted data and assessed risk of bias and characteristics of included

  15. Robust Spacecraft Component Detection in Point Clouds

    Directory of Open Access Journals (Sweden)

    Quanmao Wei

    2018-03-01

    Full Text Available Automatic component detection of spacecraft can assist in on-orbit operation and space situational awareness. Spacecraft are generally composed of solar panels and cuboidal or cylindrical modules. These components can be simply represented by geometric primitives like plane, cuboid and cylinder. Based on this prior, we propose a robust automatic detection scheme to automatically detect such basic components of spacecraft in three-dimensional (3D point clouds. In the proposed scheme, cylinders are first detected in the iteration of the energy-based geometric model fitting and cylinder parameter estimation. Then, planes are detected by Hough transform and further described as bounded patches with their minimum bounding rectangles. Finally, the cuboids are detected with pair-wise geometry relations from the detected patches. After successive detection of cylinders, planar patches and cuboids, a mid-level geometry representation of the spacecraft can be delivered. We tested the proposed component detection scheme on spacecraft 3D point clouds synthesized by computer-aided design (CAD models and those recovered by image-based reconstruction, respectively. Experimental results illustrate that the proposed scheme can detect the basic geometric components effectively and has fine robustness against noise and point distribution density.

  16. Robust Spacecraft Component Detection in Point Clouds.

    Science.gov (United States)

    Wei, Quanmao; Jiang, Zhiguo; Zhang, Haopeng

    2018-03-21

    Automatic component detection of spacecraft can assist in on-orbit operation and space situational awareness. Spacecraft are generally composed of solar panels and cuboidal or cylindrical modules. These components can be simply represented by geometric primitives like plane, cuboid and cylinder. Based on this prior, we propose a robust automatic detection scheme to automatically detect such basic components of spacecraft in three-dimensional (3D) point clouds. In the proposed scheme, cylinders are first detected in the iteration of the energy-based geometric model fitting and cylinder parameter estimation. Then, planes are detected by Hough transform and further described as bounded patches with their minimum bounding rectangles. Finally, the cuboids are detected with pair-wise geometry relations from the detected patches. After successive detection of cylinders, planar patches and cuboids, a mid-level geometry representation of the spacecraft can be delivered. We tested the proposed component detection scheme on spacecraft 3D point clouds synthesized by computer-aided design (CAD) models and those recovered by image-based reconstruction, respectively. Experimental results illustrate that the proposed scheme can detect the basic geometric components effectively and has fine robustness against noise and point distribution density.

  17. Attitude coordination for spacecraft formation with multiple communication delays

    Directory of Open Access Journals (Sweden)

    Guo Yaohua

    2015-04-01

    Full Text Available Communication delays are inherently present in information exchange between spacecraft and have an effect on the control performance of spacecraft formation. In this work, attitude coordination control of spacecraft formation is addressed, which is in the presence of multiple communication delays between spacecraft. Virtual system-based approach is utilized in case that a constant reference attitude is available to only a part of the spacecraft. The feedback from the virtual systems to the spacecraft formation is introduced to maintain the formation. Using backstepping control method, input torque of each spacecraft is designed such that the attitude of each spacecraft converges asymptotically to the states of its corresponding virtual system. Furthermore, the backstepping technique and the Lyapunov–Krasovskii method contribute to the control law design when the reference attitude is time-varying and can be obtained by each spacecraft. Finally, effectiveness of the proposed methodology is illustrated by the numerical simulations of a spacecraft formation.

  18. Guidance and control of swarms of spacecraft

    Science.gov (United States)

    Morgan, Daniel James

    There has been considerable interest in formation flying spacecraft due to their potential to perform certain tasks at a cheaper cost than monolithic spacecraft. Formation flying enables the use of smaller, cheaper spacecraft that distribute the risk of the mission. Recently, the ideas of formation flying have been extended to spacecraft swarms made up of hundreds to thousands of 100-gram-class spacecraft known as femtosatellites. The large number of spacecraft and limited capabilities of each individual spacecraft present a significant challenge in guidance, navigation, and control. This dissertation deals with the guidance and control algorithms required to enable the flight of spacecraft swarms. The algorithms developed in this dissertation are focused on achieving two main goals: swarm keeping and swarm reconfiguration. The objectives of swarm keeping are to maintain bounded relative distances between spacecraft, prevent collisions between spacecraft, and minimize the propellant used by each spacecraft. Swarm reconfiguration requires the transfer of the swarm to a specific shape. Like with swarm keeping, minimizing the propellant used and preventing collisions are the main objectives. Additionally, the algorithms required for swarm keeping and swarm reconfiguration should be decentralized with respect to communication and computation so that they can be implemented on femtosats, which have limited hardware capabilities. The algorithms developed in this dissertation are concerned with swarms located in low Earth orbit. In these orbits, Earth oblateness and atmospheric drag have a significant effect on the relative motion of the swarm. The complicated dynamic environment of low Earth orbits further complicates the swarm-keeping and swarm-reconfiguration problems. To better develop and test these algorithms, a nonlinear, relative dynamic model with J2 and drag perturbations is developed. This model is used throughout this dissertation to validate the algorithms

  19. Evaluation of spacecraft technology programs (effects on communication satellite business ventures), volume 1

    Science.gov (United States)

    Greenburg, J. S.; Gaelick, C.; Kaplan, M.; Fishman, J.; Hopkins, C.

    1985-01-01

    Commercial organizations as well as government agencies invest in spacecraft (S/C) technology programs that are aimed at increasing the performance of communications satellites. The value of these programs must be measured in terms of their impacts on the financial performane of the business ventures that may ultimately utilize the communications satellites. An economic evaluation and planning capability was developed and used to assess the impact of NASA on-orbit propulsion and space power programs on typical fixed satellite service (FSS) and direct broadcast service (DBS) communications satellite business ventures. Typical FSS and DBS spin and three-axis stabilized spacecraft were configured in the absence of NASA technology programs. These spacecraft were reconfigured taking into account the anticipated results of NASA specified on-orbit propulsion and space power programs. In general, the NASA technology programs resulted in spacecraft with increased capability. The developed methodology for assessing the value of spacecraft technology programs in terms of their impact on the financial performance of communication satellite business ventures is described. Results of the assessment of NASA specified on-orbit propulsion and space power technology programs are presented for typical FSS and DBS business ventures.

  20. Developing Sustainable Spacecraft Water Management Systems

    Science.gov (United States)

    Thomas, Evan A.; Klaus, David M.

    2009-01-01

    It is well recognized that water handling systems used in a spacecraft are prone to failure caused by biofouling and mineral scaling, which can clog mechanical systems and degrade the performance of capillary-based technologies. Long duration spaceflight applications, such as extended stays at a Lunar Outpost or during a Mars transit mission, will increasingly benefit from hardware that is generally more robust and operationally sustainable overtime. This paper presents potential design and testing considerations for improving the reliability of water handling technologies for exploration spacecraft. Our application of interest is to devise a spacecraft wastewater management system wherein fouling can be accommodated by design attributes of the management hardware, rather than implementing some means of preventing its occurrence.

  1. Embedded Thermal Control for Spacecraft Subsystems Miniaturization

    Science.gov (United States)

    Didion, Jeffrey R.

    2014-01-01

    Optimization of spacecraft size, weight and power (SWaP) resources is an explicit technical priority at Goddard Space Flight Center. Embedded Thermal Control Subsystems are a promising technology with many cross cutting NSAA, DoD and commercial applications: 1.) CubeSatSmallSat spacecraft architecture, 2.) high performance computing, 3.) On-board spacecraft electronics, 4.) Power electronics and RF arrays. The Embedded Thermal Control Subsystem technology development efforts focus on component, board and enclosure level devices that will ultimately include intelligent capabilities. The presentation will discuss electric, capillary and hybrid based hardware research and development efforts at Goddard Space Flight Center. The Embedded Thermal Control Subsystem development program consists of interrelated sub-initiatives, e.g., chip component level thermal control devices, self-sensing thermal management, advanced manufactured structures. This presentation includes technical status and progress on each of these investigations. Future sub-initiatives, technical milestones and program goals will be presented.

  2. Relativistic Spacecraft Propelled by Directed Energy

    Science.gov (United States)

    Kulkarni, Neeraj; Lubin, Philip; Zhang, Qicheng

    2018-04-01

    Achieving relativistic flight to enable extrasolar exploration is one of the dreams of humanity and the long-term goal of our NASA Starlight program. We derive a relativistic solution for the motion of a spacecraft propelled by radiation pressure from a directed energy (DE) system. Depending on the system parameters, low-mass spacecraft can achieve relativistic speeds, thus enabling interstellar exploration. The diffraction of the DE system plays an important role and limits the maximum speed of the spacecraft. We consider “photon recycling” as a possible method to achieving higher speeds. We also discuss recent claims that our previous work on this topic is incorrect and show that these claims arise from an improper treatment of causality.

  3. Numerical Analysis of Magnetic Sail Spacecraft

    International Nuclear Information System (INIS)

    Sasaki, Daisuke; Yamakawa, Hiroshi; Usui, Hideyuki; Funaki, Ikkoh; Kojima, Hirotsugu

    2008-01-01

    To capture the kinetic energy of the solar wind by creating a large magnetosphere around the spacecraft, magneto-plasma sail injects a plasma jet into a strong magnetic field produced by an electromagnet onboard the spacecraft. The aim of this paper is to investigate the effect of the IMF (interplanetary magnetic field) on the magnetosphere of magneto-plasma sail. First, using an axi-symmetric two-dimensional MHD code, we numerically confirm the magnetic field inflation, and the formation of a magnetosphere by the interaction between the solar wind and the magnetic field. The expansion of an artificial magnetosphere by the plasma injection is then simulated, and we show that the magnetosphere is formed by the interaction between the solar wind and the magnetic field expanded by the plasma jet from the spacecraft. This simulation indicates the size of the artificial magnetosphere becomes smaller when applying the IMF.

  4. Autonomous Spacecraft Communication Interface for Load Planning

    Science.gov (United States)

    Dever, Timothy P.; May, Ryan D.; Morris, Paul H.

    2014-01-01

    Ground-based controllers can remain in continuous communication with spacecraft in low Earth orbit (LEO) with near-instantaneous communication speeds. This permits near real-time control of all of the core spacecraft systems by ground personnel. However, as NASA missions move beyond LEO, light-time communication delay issues, such as time lag and low bandwidth, will prohibit this type of operation. As missions become more distant, autonomous control of manned spacecraft will be required. The focus of this paper is the power subsystem. For present missions, controllers on the ground develop a complete schedule of power usage for all spacecraft components. This paper presents work currently underway at NASA to develop an architecture for an autonomous spacecraft, and focuses on the development of communication between the Mission Manager and the Autonomous Power Controller. These two systems must work together in order to plan future load use and respond to unanticipated plan deviations. Using a nominal spacecraft architecture and prototype versions of these two key components, a number of simulations are run under a variety of operational conditions, enabling development of content and format of the messages necessary to achieve the desired goals. The goals include negotiation of a load schedule that meets the global requirements (contained in the Mission Manager) and local power system requirements (contained in the Autonomous Power Controller), and communication of off-plan disturbances that arise while executing a negotiated plan. The message content is developed in two steps: first, a set of rapid-prototyping "paper" simulations are preformed; then the resultant optimized messages are codified for computer communication for use in automated testing.

  5. Navigating the MESSENGER Spacecraft through End of Mission

    Science.gov (United States)

    Bryan, C. G.; Williams, B. G.; Williams, K. E.; Taylor, A. H.; Carranza, E.; Page, B. R.; Stanbridge, D. R.; Mazarico, E.; Neumann, G. A.; O'Shaughnessy, D. J.; McAdams, J. V.; Calloway, A. B.

    2015-12-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbited the planet Mercury from March 2011 until the end of April 2015, when it impacted the planetary surface after propellant reserves used to maintain the orbit were depleted. This highly successful mission was led by the principal investigator, Sean C. Solomon, of Columbia University. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) designed and assembled the spacecraft and served as the home for spacecraft operations. Spacecraft navigation for the entirety of the mission was provided by the Space Navigation and Flight Dynamics Practice (SNAFD) of KinetX Aerospace. Orbit determination (OD) solutions were generated through processing of radiometric tracking data provided by NASA's Deep Space Network (DSN) using the MIRAGE suite of orbital analysis tools. The MESSENGER orbit was highly eccentric, with periapsis at a high northern latitude and periapsis altitude in the range 200-500 km for most of the orbital mission phase. In a low-altitude "hover campaign" during the final two months of the mission, periapsis altitudes were maintained within a narrow range between about 35 km and 5 km. Navigating a spacecraft so near a planetary surface presented special challenges. Tasks required to meet those challenges included the modeling and estimation of Mercury's gravity field and of solar and planetary radiation pressure, and the design of frequent orbit-correction maneuvers. Superior solar conjunction also presented observational modeling issues. One key to the overall success of the low-altitude hover campaign was a strategy to utilize data from an onboard laser altimeter as a cross-check on the navigation team's reconstructed and predicted estimates of periapsis altitude. Data obtained from the Mercury Laser Altimeter (MLA) on a daily basis provided near-real-time feedback that proved invaluable in evaluating alternative orbit estimation strategies, and

  6. Testing programs for the Multimission Modular Spacecraft

    Science.gov (United States)

    Greenwell, T. J.

    1978-01-01

    The Multimission Modular Spacecraft (MMS) provides a standard spacecraft bus to a user for a variety of space missions ranging from near-earth to synchronous orbits. The present paper describes the philosophy behind the MMS module test program and discusses the implementation of the test program. It is concluded that the MMS module test program provides an effective and comprehensive customer buy-off at the subsystem contractor's plant, is an optimum approach for checkout of the subsystems prior to use for on-orbit servicing in the Shuttle Cargo Bay, and is a cost-effective technique for environmental testing.

  7. Robust Parametric Control of Spacecraft Rendezvous

    Directory of Open Access Journals (Sweden)

    Dake Gu

    2014-01-01

    Full Text Available This paper proposes a method to design the robust parametric control for autonomous rendezvous of spacecrafts with the inertial information with uncertainty. We consider model uncertainty of traditional C-W equation to formulate the dynamic model of the relative motion. Based on eigenstructure assignment and model reference theory, a concise control law for spacecraft rendezvous is proposed which could be fixed through solving an optimization problem. The cost function considers the stabilization of the system and other performances. Simulation results illustrate the robustness and effectiveness of the proposed control.

  8. Spacecraft charging: incoming and outgoing electrons

    CERN Document Server

    Lai, Shu T.

    2013-04-22

    This paper presents an overview of the roles played by incoming and outgoing electrons in spacecraft surface and stresses the importance of surface conditions for spacecraft charging. The balance between the incoming electron current from the ambient plasma and the outgoing currents of secondary electrons, backscattered electrons, and photoelectrons from the surfaces determines the surface potential. Since surface conditions significantly affect the outgoing currents, the critical temperature and the surface potential are also significantly affected. As a corollary, high level differential charging of adjacent surfaces with very different surface conditions is a space hazard.

  9. Event-triggered attitude control of spacecraft

    Science.gov (United States)

    Wu, Baolin; Shen, Qiang; Cao, Xibin

    2018-02-01

    The problem of spacecraft attitude stabilization control system with limited communication and external disturbances is investigated based on an event-triggered control scheme. In the proposed scheme, information of attitude and control torque only need to be transmitted at some discrete triggered times when a defined measurement error exceeds a state-dependent threshold. The proposed control scheme not only guarantees that spacecraft attitude control errors converge toward a small invariant set containing the origin, but also ensures that there is no accumulation of triggering instants. The performance of the proposed control scheme is demonstrated through numerical simulation.

  10. The spacecraft encounters of Comet Halley

    Science.gov (United States)

    Asoka Mendis, D.; Tsurutani, Bruce T.

    1986-01-01

    The characteristics of the Comet Halley spacecraft 'fleet' (VEGA 1 and VEGA 2, Giotto, Suisei, and Sakigake) are presented. The major aims of these missions were (1) to discover and characterize the nucleus, (2) to characterize the atmosphere and ionosphere, (3) to characterize the dust, and (4) to characterize the nature of the large-scale comet-solar wind interaction. While the VEGA and Giotto missions were designed to study all four areas, Suisei addressed the second and fourth. Sakigake was designed to study the solar wind conditions upstream of the comet. It is noted that NASA's Deep Space Network played an important role in spacecraft tracking.

  11. Shades of green: A bird's eye view of wind energy; L'energie eolienne et son impact sur les oiseaux

    Energy Technology Data Exchange (ETDEWEB)

    Whittam, B.; Kingsley, A.

    2003-03-31

    The issue of birds being killed by wind turbines is discussed. The substance of the argument is that contrary to beliefs held primarily by those opposed to wind turbine developments, when correctly sited, wind turbines appear to have relatively little impact on birds. Historically, 'bird-kill' was a significant factor in the 1980s when a significant number of raptors were killed by wind turbines and their associated power lines in California, Tennessee, Spain and the Netherlands, where many turbines were located on major bird migration routes. Based on experiences learned from these occurrences, several countries have produced bird-focused guidelines for the siting of wind turbines. In Canada, Bird Studies Canada was recently contracted by Environment Canada to produce guidelines for the environmental assessment of wind turbine projects related to birds. The objective of the guidelines is to help prevent adverse impacts on birds, whether the impact is related to habitat disturbance or collision. Based on American studies, it is estimated that 2.19 birds are killed annually at each wind turbine in California; the estimated fatality rate elsewhere in the United States is 1.83. That works out to 33,000 dead birds (based on 15,000 wind turbines), a large number, but relatively small when compared with the millions of birds that travel over windfarms each year, or when compared to the many millions of birds that die annually due to collisions with transmission lines, vehicles, buildings and communication towers. Nevertheless, there is room for concern. Bird Studies Canada is particularly concerned about the growing offshore wind industry and its potential to disrupt songbird migration, waterfowl staging areas and the prey base of seabirds. In general, Bird Studies Canada advises against siting large wind facilities in areas heavily travelled by birds, and is firmly opposed to placing wind turbines in areas known to provide critical habitat for Species At Risk

  12. King and Eye

    DEFF Research Database (Denmark)

    Suwannakij, Sing

    King and Eye explores the visual formation of kingship in Siam in its multifarious aspects. This dissertation identifies the leitmotifs in the dynamics between seeing the king and being seen by him, which burst forth in different eras. The visual sense has been a repository for the ontologization...... devices, most significantly the photographic and the cine cameras, but also encompassing other ocular apparatuses. The images produced through the contraptions were brought together under the royal eye at the apex, which in turn claimed its supremacy over space, time, and the vast and diverse population...

  13. Danish Rural Eye Study

    DEFF Research Database (Denmark)

    Høeg, Tracy B; Moldow, Birgitte; Ellervik, Christina

    2015-01-01

    and older from a Danish rural municipality received a complete general health examination and an ophthalmological interview and examination. This study included a comprehensive ophthalmologic interview, measurement of best corrected visual acuity (BCVA) in each eye, Hirschberg's test for strabismus and two...... 45-degree retinal fundus photographs of each eye. A complete ophthalmologic examination was performed when indicated. RESULTS: The prevalence of monocular visual impairment (MVI) was 4.26% (95% CI, 3.66-4.95, n = 163). Amblyopia was the most common cause, accounting for 33%. The prevalence...

  14. Glaucoma: Eye-to-Eye with Dr. Rachel Bishop

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Glaucoma Eye-to-Eye with Dr. Rachel Bishop Past ... nerves are pale and cupped—signs of advanced glaucoma. Yet the patient wasn't aware of any ...

  15. Spacecraft Architecture and environmental pshychology

    Science.gov (United States)

    Ören, Ayşe

    2016-07-01

    As we embark on a journey for new homes in the new worlds to lay solid foundations, we should consider not only the survival of frontiers but also well-being of those to live in zero gravity. As a versatile science, architecture encompasses abstract human needs as well. On our new different direction in the course of the Homo sapiens evolution, we can do this with designs addressing both our needs and senses. Well-being of humans can be achieved by creating environments supporting the cognitive and social stages in the evolution process. Space stations are going through their own evolution process. Any step taken can serve as a reference for further attempts. When studying the history of architecture, window designing is discussed in a later phase, which is the case for building a spaceship as well. We lean on the places we live both physically and metaphorically. The feeling of belonging is essential here, entailing trans-humanism, which is significant since the environment therein is like a dress comfortable enough to fit in, meeting needs without any burden. Utilizing the advent of technology, we can create moods and atmospheres to regulate night and day cycles, thus we can turn claustrophobic places into cozy or dream-like places. Senses provoke a psychological sensation going beyond cultural codes as they are rooted within consciousness, which allows designers to create a mood within a space that tells a story and evokes an emotional impact. Color, amount of light, sound and odor are not superficial. As much as intangible, they are real and powerful tools with a physical presence. Tapping into induction, we can solve a whole system based on a part thereof. Therefore, fractal designs may not yield good results unless used correctly in terms of design although they are functional, which makes geometric arrangement critical.

  16. Spacecraft Architecture and well being

    Science.gov (United States)

    Ören, Ayşe

    2016-07-01

    As we embark on a journey for new homes in the new worlds to lay solid foundations, we should consider not only the survival of frontiers but also well-being of those to live in zero gravity. As a versatile science, architecture encompasses abstract human needs as well. On our new different direction in the course of the Homo sapiens evolution, we can do this with designs addressing both our needs and senses. Well-being of humans can be achieved by creating environments supporting the cognitive and social stages in the evolution process. Space stations are going through their own evolution process. Any step taken can serve as a reference for further attempts. When studying the history of architecture, window designing is discussed in a later phase, which is the case for building a spaceship as well. We lean on the places we live both physically and metaphorically. The feeling of belonging is essential here, entailing trans-humanism, which is significant since the environment therein is like a dress comfortable enough to fit in, meeting needs without any burden. Utilizing the advent of technology, we can create moods and atmospheres to regulate night and day cycles, thus we can turn claustrophobic places into cozy or dream-like places. Senses provoke a psychological sensation going beyond cultural codes as they are rooted within consciousness, which allows designers to create a mood within a space that tells a story and evokes an emotional impact. Color, amount of light, sound and odor are not superficial. As much as intangible, they are real and powerful tools with a physical presence. Tapping into induction, we can solve a whole system based on a part thereof. Therefore, fractal designs may not yield good results unless used correctly in terms of design although they are functional, which makes geometric arrangement critical.

  17. Assessing the Usability of Gaze-Adapted Interface against Conventional Eye-based Input Emulation

    OpenAIRE

    Kumar, Chandan; Menges, Raphael; Staab, Steffen

    2017-01-01

    In recent years, eye tracking systems have greatly improved, beginning to play a promising role as an input medium. Eye trackers can be used for application control either by simply emulating the mouse and keyboard devices in the traditional graphical user interface, or by customized interfaces for eye gaze events. In this work, we evaluate these two approaches to assess their impact in usability. We present a gaze-adapted Twitter application interface with direct interaction of eye gaze inpu...

  18. Naked-eye astronomy in mass tourism

    Directory of Open Access Journals (Sweden)

    Tadić Milutin

    2016-01-01

    Full Text Available This paper considers the possibility of developing astro-tourism in small countries such as Serbia and other Balkan countries, with "discreet" astro-tourism reduced to naked-eye astronomy as part of mass tourism rather than elite tourism that is realized through specialized programs with spacecraft and space stations, spectacular planetariums and observatories with giant telescopes. The specific relationship between the virtual and the real world is highlighted in this paper especially when considering younger generations. Furthermore, the differences in the way stars are perceived by astronomers and "ordinary" tourists or non-astronomers is also emphasized. Tourists are not enchanted by celestial bodies themselves, but by a complete scene, which consists of integrated skyscapes and landscapes, as a complex stage where in various combinations and forms these celestial bodies are observed, and of their own experience. These complex sky-earth landscapes, astro-landscapes, present astro-tourism resources of the small countries like Serbia, provided that a tourist can "read" their astronomical text. In this regard, Belgrade was used as the example for drafting a "package" of astronomical information that can be easily prepared and adapted according to the needs of a particular group, so that every tourist may know what can be seen, where and when. With the help of a rotating star map (planisphere, visitors may observe the sky with the naked eye.

  19. About the Eye

    Medline Plus

    Full Text Available ... programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and ... is the center of the macula, where your vision is sharpest. Optic nerve (OP-tic nurv) is the bundle of more than 1 ...

  20. Eye Injuries in Construction

    Science.gov (United States)

    ... cold helps keep down pain and swelling. If pain continues or your vision is blurry, get to a doctor right away. ! If you get hit in the eye with flying metal, wood, or material from a power tool (like a drill or wheel) , OR ! If ...

  1. Robustifying eye interaction

    DEFF Research Database (Denmark)

    Hansen, Dan Witzner; Hansen, John Paulin

    2006-01-01

    This paper presents a gaze typing system based on consumer hardware. Eye tracking based on consumer hardware is subject to several unknown factors. We propose methods using robust statistical principles to accommodate uncertainties in image data as well as in gaze estimates to improve accuracy. We...

  2. About the Eye

    Medline Plus

    Full Text Available ... Accomplishments Budget and Congress About the NEI Director History of the NEI NEI 50th Anniversary NEI Women Scientists Advisory Committee (WSAC) Board of Scientific Counselors National Advisory Eye Council (NAEC) Donating to the NEI Contact Us Visiting the NIH Campus Mission Statement As part ...

  3. About the Eye

    Medline Plus

    Full Text Available ... Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect ... Emily Y. Chew, M.D., Deputy Clinical Director Education Programs National Eye Health Education Program (NEHEP) Diabetic ...

  4. About the Eye

    Medline Plus

    Full Text Available ... of Epidemiology and Clinical Applications eyeGENE Research Directors Office Office of the Scientific Director Sheldon S. Miller, Ph.D., ... David M. Schneeweis, Ph.D., Deputy Scientific Director Office of the Clinical Director Brian P. Brooks, M. ...

  5. What Is Dry Eye?

    Medline Plus

    Full Text Available ... type of tears or tear film . How do tears work? When you blink, a film of tears spreads over the eye. This keeps the eye’s surface smooth and clear. The tear film is important for good vision. The tear ...

  6. LASIK - Laser Eye Surgery

    Science.gov (United States)

    ... Refractive Surgery Procedures What Is Photorefractive Keratectomy (PRK)? LASIK — Laser Eye Surgery Leer en Español: LASIK—Cirugía ocular con láser ... loss of close-up focusing power. How the LASIK procedure works LASIK is performed while the patient ...

  7. What Is Dry Eye?

    Medline Plus

    Full Text Available ... make the right type of tears or tear film . How do tears work? When you blink, a film of tears spreads over the eye. This keeps the eye’s surface smooth and clear. The tear film is important for good vision. The tear film ...

  8. About the Eye

    Medline Plus

    Full Text Available ... Ask a Scientist Video Series Glossary The Visual System Your Eyes’ Natural Defenses Eye Health and Safety ... Employee Emergency Information NEI Intranet (Employees Only) *PDF files require the free Adobe® Reader® software for viewing. ...

  9. Eyes on the Road

    Centers for Disease Control (CDC) Podcasts

    One of the first lessons new drivers learn is to keep their eyes on the road. Unfortunately, cell phones and other electronic devices are causing many drivers to lose their focus, and sometimes their lives. In this podcast, Rebecca Naumann discusses the dangers of distracted driving.

  10. The Learned Eye

    NARCIS (Netherlands)

    Doel, van den Marieke; Eck, van Natasja; Korevaar, Gerbrand; Tummers, Anna; Weststeijn, Thijs

    2005-01-01

    The 'learned eye' or oculus eruditus was a concept used by seventeenth-century writers on painting. It illustrated their view that the ideal artist was not only skilled in painting techniques, but also had knowledge of the history of art and an interest in poetry and literature.In this book,

  11. About the Eye

    Medline Plus

    Full Text Available ... Units Division of Epidemiology and Clinical Applications eyeGENE Research Directors Office Office of the Scientific Director Sheldon S. ... NEI Intranet (Employees Only) *PDF files require the free Adobe® Reader® software for viewing. This website is ...

  12. Laser photocoagulation - eye

    Science.gov (United States)

    ... an eye disorder that slowly destroys sharp, central vision A tear in the retina A blockage of the small veins that carry ... Since parts of the retina are burned, you may develop: Mild loss ... vision If not treated, diabetic retinopathy can cause permanent ...

  13. About the Eye

    Medline Plus

    Full Text Available ... with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the ... Contact Us A-Z Site Map NEI on Social Media Information in Spanish (Información en español) Website, ...

  14. About the Eye

    Medline Plus

    Full Text Available ... to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and requirements of ... Pressroom Contacts Dustin Hays - Chief, Science Communication dustin.hays@nih.gov Kathryn DeMott, Media Relations ...

  15. Eye Cosmetic Safety

    Science.gov (United States)

    ... you're wearing? In the United States, the use of color additives is strictly regulated. A number of color ... to color additives that are not approved for use in the area of the eye. Avoid color additives that are not approved for use in ...

  16. About the Eye

    Medline Plus

    Full Text Available ... programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health ... Pressroom Contacts Dustin Hays - Chief, Science Communication dustin.hays@nih.gov Kathryn DeMott, Media Relations ...

  17. About the Eye

    Medline Plus

    Full Text Available ... blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and requirements of the blind.” ... DeMott, Media Relations Kathryn.DeMott@nih.gov NEI Office of Communications ( ...

  18. About the Eye

    Medline Plus

    Full Text Available ... the white outer coating of the eye. Vitreous humor (VIT-ree-us HYOO-mer) is the clear ... in Spanish (Información en español) Website, Social Media Policies and Other Important Links NEI Employee Emergency Information ...

  19. Software for Engineering Simulations of a Spacecraft

    Science.gov (United States)

    Shireman, Kirk; McSwain, Gene; McCormick, Bernell; Fardelos, Panayiotis

    2005-01-01

    Spacecraft Engineering Simulation II (SES II) is a C-language computer program for simulating diverse aspects of operation of a spacecraft characterized by either three or six degrees of freedom. A functional model in SES can include a trajectory flight plan; a submodel of a flight computer running navigational and flight-control software; and submodels of the environment, the dynamics of the spacecraft, and sensor inputs and outputs. SES II features a modular, object-oriented programming style. SES II supports event-based simulations, which, in turn, create an easily adaptable simulation environment in which many different types of trajectories can be simulated by use of the same software. The simulation output consists largely of flight data. SES II can be used to perform optimization and Monte Carlo dispersion simulations. It can also be used to perform simulations for multiple spacecraft. In addition to its generic simulation capabilities, SES offers special capabilities for space-shuttle simulations: for this purpose, it incorporates submodels of the space-shuttle dynamics and a C-language version of the guidance, navigation, and control components of the space-shuttle flight software.

  20. How Spacecraft Fly Spaceflight Without Formulae

    CERN Document Server

    Swinerd, Graham

    2009-01-01

    About half a century ago a small satellite, Sputnik 1, was launched. The satellite did very little other than to transmit a radio signal to announce its presence in orbit. However, this humble beginning heralded the dawn of the Space Age. Today literally thousands of robotic spacecraft have been launched, many of which have flown to far-flung regions of the Solar System carrying with them the human spirit of scientific discovery and exploration. Numerous other satellites have been launched in orbit around the Earth providing services that support our technological society on the ground. How Spacecraft Fly: Spaceflight Without Formulae by Graham Swinerd focuses on how these spacecraft work. The book opens with a historical perspective of how we have come to understand our Solar System and the Universe. It then progresses through orbital flight, rocket science, the hostile environment within which spacecraft operate, and how they are designed. The concluding chapters give a glimpse of what the 21st century may ...

  1. Microgravity Flammability Experiments for Spacecraft Fire Safety

    DEFF Research Database (Denmark)

    Legros, Guillaume; Minster, Olivier; Tóth, Balazs

    2012-01-01

    As fire behaviour in manned spacecraft still remains poorly understood, an international topical team has been created to design a validation experiment that has an unprecedented large scale for a microgravity flammability experiment. While the validation experiment is being designed for a re-sup...

  2. Parameter Estimation of Spacecraft Fuel Slosh Model

    Science.gov (United States)

    Gangadharan, Sathya; Sudermann, James; Marlowe, Andrea; Njengam Charles

    2004-01-01

    Fuel slosh in the upper stages of a spinning spacecraft during launch has been a long standing concern for the success of a space mission. Energy loss through the movement of the liquid fuel in the fuel tank affects the gyroscopic stability of the spacecraft and leads to nutation (wobble) which can cause devastating control issues. The rate at which nutation develops (defined by Nutation Time Constant (NTC can be tedious to calculate and largely inaccurate if done during the early stages of spacecraft design. Pure analytical means of predicting the influence of onboard liquids have generally failed. A strong need exists to identify and model the conditions of resonance between nutation motion and liquid modes and to understand the general characteristics of the liquid motion that causes the problem in spinning spacecraft. A 3-D computerized model of the fuel slosh that accounts for any resonant modes found in the experimental testing will allow for increased accuracy in the overall modeling process. Development of a more accurate model of the fuel slosh currently lies in a more generalized 3-D computerized model incorporating masses, springs and dampers. Parameters describing the model include the inertia tensor of the fuel, spring constants, and damper coefficients. Refinement and understanding the effects of these parameters allow for a more accurate simulation of fuel slosh. The current research will focus on developing models of different complexity and estimating the model parameters that will ultimately provide a more realistic prediction of Nutation Time Constant obtained through simulation.

  3. Spacecraft 3D Augmented Reality Mobile App

    Science.gov (United States)

    Hussey, Kevin J.; Doronila, Paul R.; Kumanchik, Brian E.; Chan, Evan G.; Ellison, Douglas J.; Boeck, Andrea; Moore, Justin M.

    2013-01-01

    The Spacecraft 3D application allows users to learn about and interact with iconic NASA missions in a new and immersive way using common mobile devices. Using Augmented Reality (AR) techniques to project 3D renditions of the mission spacecraft into real-world surroundings, users can interact with and learn about Curiosity, GRAIL, Cassini, and Voyager. Additional updates on future missions, animations, and information will be ongoing. Using a printed AR Target and camera on a mobile device, users can get up close with these robotic explorers, see how some move, and learn about these engineering feats, which are used to expand knowledge and understanding about space. The software receives input from the mobile device's camera to recognize the presence of an AR marker in the camera's field of view. It then displays a 3D rendition of the selected spacecraft in the user's physical surroundings, on the mobile device's screen, while it tracks the device's movement in relation to the physical position of the spacecraft's 3D image on the AR marker.

  4. Special Semaphore Scheme for UHF Spacecraft Communications

    Science.gov (United States)

    Butman, Stanley; Satorius, Edgar; Ilott, Peter

    2006-01-01

    A semaphore scheme has been devised to satisfy a requirement to enable ultrahigh- frequency (UHF) radio communication between a spacecraft descending from orbit to a landing on Mars and a spacecraft, in orbit about Mars, that relays communications between Earth and the lander spacecraft. There are also two subsidiary requirements: (1) to use UHF transceivers, built and qualified for operation aboard the spacecraft that operate with residual-carrier binary phase-shift-keying (BPSK) modulation at a selectable data rate of 8, 32, 128, or 256 kb/s; and (2) to enable low-rate signaling even when received signals become so weak as to prevent communication at the minimum BPSK rate of 8 kHz. The scheme involves exploitation of Manchester encoding, which is used in conjunction with residual-carrier modulation to aid the carrier-tracking loop. By choosing various sequences of 1s, 0s, or 1s alternating with 0s to be fed to the residual-carrier modulator, one would cause the modulator to generate sidebands at a fundamental frequency of 4 or 8 kHz and harmonics thereof. These sidebands would constitute the desired semaphores. In reception, the semaphores would be detected by a software demodulator.

  5. Accelerated life testing of spacecraft subsystems

    Science.gov (United States)

    Wiksten, D.; Swanson, J.

    1972-01-01

    The rationale and requirements for conducting accelerated life tests on electronic subsystems of spacecraft are presented. A method for applying data on the reliability and temperature sensitivity of the parts contained in a sybsystem to the selection of accelerated life test parameters is described. Additional considerations affecting the formulation of test requirements are identified, and practical limitations of accelerated aging are described.

  6. Rotational Motion Control of a Spacecraft

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    2001-01-01

    The paper adopts the energy shaping method to control of rotational motion. A global representation of the rigid body motion is given in the canonical form by a quaternion and its conjugate momenta. A general method for motion control on a cotangent bundle to the 3-sphere is suggested. The design...... algorithm is validated for three-axis spacecraft attitude control...

  7. Rotational motion control of a spacecraft

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    2003-01-01

    The paper adopts the energy shaping method to control of rotational motion. A global representation of the rigid body motion is given in the canonical form by a quaternion and its conjugate momenta. A general method for motion control on a cotangent bundle to the 3-sphere is suggested. The design...... algorithm is validated for three-axis spacecraft attitude control. Udgivelsesdato: APR...

  8. Small Spacecraft Technology Initiative Education Program

    Science.gov (United States)

    1995-01-01

    A NASA engineer with the Commercial Remote Sensing Program (CRSP) at Stennis Space Center works with students from W.P. Daniels High School in New Albany, Miss., through NASA's Small Spacecraft Technology Initiative Program. CRSP is teaching students to use remote sensing to locate a potential site for a water reservoir to offset a predicted water shortage in the community's future.

  9. Spacecraft Attitude Control in Hamiltonian Framework

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    The objective of this paper is to give a design scheme for attitude control algorithms of a generic spacecraft. Along with the system model formulated in the Hamilton's canonical form the algorithm uses information about a required potential energy and a dissipative term. The control action...

  10. Using an eye tracker for accurate eye movement artifact correction

    NARCIS (Netherlands)

    Kierkels, J.J.M.; Riani, J.; Bergmans, J.W.M.; Boxtel, van G.J.M.

    2007-01-01

    We present a new method to correct eye movement artifacts in electroencephalogram (EEG) data. By using an eye tracker, whose data cannot be corrupted by any electrophysiological signals, an accurate method for correction is developed. The eye-tracker data is used in a Kalman filter to estimate which

  11. Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior

    Science.gov (United States)

    Klem, B.; Swann, D.

    2011-09-01

    Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the radiation patterns exhibit a time varying reflective glint superimposed on an underlying diffuse signal contribute to assessment of spacecraft behavior in two ways: (1) providing information on body component orientation and attitude; and, (2) detecting changes in surface material properties due to the space environment. Simple convex and cube-shaped spacecraft, designed to operate without protruding solar panel appendages, may require an enhanced level of preflight characterization to support interpretation of the various physical effects observed during on-orbit monitoring. This paper describes selected portions of the signature database generated using streamlined signature modeling and simulations of basic geometry shapes apparent to non-imaging sensors. With this database, summarization of key observable features for such shapes as spheres, cylinders, flat plates, cones, and cubes in specific spectral bands that include the visible, mid wave, and long wave infrared provide the analyst with input to the decision process algorithms contained in the overall sensing and identification architectures. The models typically utilize baseline materials such as Kapton, paints, aluminum surface end plates, and radiators, along with solar cell representations covering the cylindrical and side portions of the spacecraft. Multiple space and ground-based sensors are assumed to be located at key locations to describe the comprehensive multi-viewing aspect scenarios that can result in significant specular reflection

  12. Conjunctivitis (Pink Eye) in Newborns

    Science.gov (United States)

    ... as well as the sexually transmitted infection called gonorrhea. Women with untreated gonorrhea can pass the bacteria to her baby during ... conjunctivitis is less common than conjunctivitis caused by gonorrhea and chlamydia. Symptoms usually include red eye(s) and ...

  13. On the spacecraft attitude stabilization in the orbital frame

    Directory of Open Access Journals (Sweden)

    Antipov Kirill A.

    2012-01-01

    Full Text Available The paper deals with spacecraft in the circular near-Earth orbit. The spacecraft interacts with geomagnetic field by the moments of Lorentz and magnetic forces. The octupole approximation of the Earth’s magnetic field is accepted. The spacecraft electromagnetic parameters, namely the electrostatic charge moment of the first order and the eigen magnetic moment are the controlled quasiperiodic functions. The control algorithms for the spacecraft electromagnetic parameters, which allows to stabilize the spacecraft attitude position in the orbital frame are obtained. The stability of the spacecraft stabilized orientation is proved both analytically and by PC computations.

  14. Protecting Spacecraft Fragments from Exposure to Small Debris

    Directory of Open Access Journals (Sweden)

    V. V. Zelentsov

    2015-01-01

    Full Text Available Since the launch of the first artificial Earth satellite a large amount of space debris has been accumulated in near-earth space. This debris comprises the exhausted spacecrafts, final stages of rocket-carriers and boosters, technological space junk, consisting of the structure elements, which are separated when deploying the solar arrays, antennas etc., as well as when undocking a booster and a spacecraft. All the debris is divided into observable one of over 100 mm in size and unobservable debris. In case of possible collision with the observed debris an avoidance manoeuvre is provided. The situation with unobservable debris is worse, its dimensions ranging from 100 mm to several microns. This debris is formed as a result of explosions of dead space objects and at collisions of destroyed spacecraft fragments against each other. This debris moves along arbitrary trajectories at different speeds.At collision of a spacecraft with fragments of small-size space debris, various consequences are possible: the device can immediately fail, suffer damages, which will have effect later and damages, which break no bones to the aircraft. Anyway, the spacecraft collision with small-size debris particles is undesirable. The protective shields are used to protect the aircraft from damage. Development of shield construction is complicated because the high cost of launch makes it impossible to conduct field tests of shields in space. All the work is carried out in the laboratory, with particles having co-impact speeds up to 10 km/s (possible speeds are up to 20 km/s and spherically shaped particles of 0.8 ... 3 mm in diameter.Various materials are used to manufacture shields. These are aluminum sheet, sandwich panels, metal mesh, metal foam, and woven materials (ballistic fabric. The paper considers single-layer (from sheet metal sandwich materials and multilayer shield designs. As experimental studies show, a single-layer shield protects colliding at speeds

  15. Effectiveness of eye armor during blast loading.

    Science.gov (United States)

    Bailoor, Shantanu; Bhardwaj, Rajneesh; Nguyen, Thao D

    2015-11-01

    Ocular trauma is one of the most common types of combat injuries resulting from the interaction of military personnel with improvised explosive devices. Ocular blast injury mechanisms are complex, and trauma may occur through various injury mechanisms. However, primary blast injuries (PBI) are an important cause of ocular trauma that may go unnoticed and result in significant damage to internal ocular tissues and visual impairment. Further, the effectiveness of commonly employed eye armor, designed for ballistic and laser protection, in lessening the severity of adverse blast overpressures (BOP) is unknown. In this paper, we employed a three-dimensional (3D) fluid-structure interaction computational model for assessing effectiveness of the eye armor during blast loading on human eyes and validated results against free field blast measurements by Bentz and Grimm (2013). Numerical simulations show that the blast waves focused on the ocular region because of reflections from surrounding facial features and resulted in considerable increase in BOP. We evaluated the effectiveness of spectacles and goggles in mitigating the pressure loading using the computational model. Our results corroborate experimental measurements showing that the goggles were more effective than spectacles in mitigating BOP loading on the eye. Numerical results confirmed that the goggles significantly reduced blast wave penetration in the space between the armor and the eyes and provided larger clearance space for blast wave expansion after penetration than the spectacles. The spectacles as well as the goggles were more effective in reducing reflected BOP at higher charge mass because of the larger decrease in dynamic pressures after the impact. The goggles provided greater benefit of reducing the peak pressure than the spectacles for lower charge mass. However, the goggles resulted in moderate, sustained elevated pressure loading on the eye, that became 50-100% larger than the pressure loading

  16. Pink Eye: What To Do

    Centers for Disease Control (CDC) Podcasts

    2010-10-12

    In this podcast, CDC's Adam Cohen, MD, a pediatrician and parent, discusses conjunctivitis (pink eye), a common eye condition in children and adults. He reviews pink eye causes and treatment, suggestions on when to call or visit a doctor, and practical tips to prevent pink eye from spreading.  Created: 10/12/2010 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 10/13/2010.

  17. Neuropathic pain and dry eye.

    Science.gov (United States)

    Galor, Anat; Moein, Hamid-Reza; Lee, Charity; Rodriguez, Adriana; Felix, Elizabeth R; Sarantopoulos, Konstantinos D; Levitt, Roy C

    2018-01-01

    Dry eye is a common, multifactorial disease currently diagnosed by a combination of symptoms and signs. Its epidemiology and clinical presentation have many similarities with neuropathic pain outside the eye. This review highlights the similarities between dry eye and neuropathic pain, focusing on clinical features, somatosensory function, and underlying pathophysiology. Implications of these similarities on the diagnosis and treatment of dry eye are discussed. Published by Elsevier Inc.

  18. Application of Space Environmental Observations to Spacecraft Pre-Launch Engineering and Spacecraft Operations

    Science.gov (United States)

    Barth, Janet L.; Xapsos, Michael

    2008-01-01

    This presentation focuses on the effects of the space environment on spacecraft systems and applying this knowledge to spacecraft pre-launch engineering and operations. Particle radiation, neutral gas particles, ultraviolet and x-rays, as well as micrometeoroids and orbital debris in the space environment have various effects on spacecraft systems, including degradation of microelectronic and optical components, physical damage, orbital decay, biasing of instrument readings, and system shutdowns. Space climate and weather must be considered during the mission life cycle (mission concept, mission planning, systems design, and launch and operations) to minimize and manage risk to both the spacecraft and its systems. A space environment model for use in the mission life cycle is presented.

  19. Keep an Eye on Your Eyes (A Minute of Health with CDC)

    Centers for Disease Control (CDC) Podcasts

    2013-05-09

    Vision problems can impact many daily activities, from reading and driving a car to preparing a meal and exercising. This podcast discusses the importance of regular eye exams.  Created: 5/9/2013 by MMWR.   Date Released: 5/9/2013.

  20. Keep an Eye on Your Eyes (A Cup of Health with CDC)

    Centers for Disease Control (CDC) Podcasts

    If you struggle to read the pages of a book or a billboard on the side of the road, you might be among the millions of Americans who suffer from vision impairment. Problems seeing can impact many daily activities. In this podcast, Dr. Jinan Saaddine discusses the importance of regular eye exams.

  1. Moving eyes and naming objects

    NARCIS (Netherlands)

    Meulen, F.F. van der

    2001-01-01

    The coordination between eye movements and speech was examined while speakers were naming objects. Earlier research has shown that eye movements reflect on the underlying visual attention. Also, eye movements were found to reflect upon not only the visual and conceptual processing of an object, but

  2. LIMNOLOGICAL OPTOMETRY: EXAMINING EARTH'S EYE

    Science.gov (United States)

    In Thoreau's Walden, a lake is described as the landscape's most expressive feature and the earth's eye. Collectively, scientists are charged by society to assess, monitor, and remedy maladies of earth's eye in the same way optometrists maintain the health of the human eye. This ...

  3. Eye Protection in Kansas Schools.

    Science.gov (United States)

    Hay, Kenneth M.; And Others

    A law passed by a state legislature requires that students in industrial arts shops and science laboratories must wear eye protective devices. Explanatory material presents the text of the bill and guidelines for implementation, including--(1) types of eye hazards, (2) types of protective devices, (3) administrating eye safety equipment, (4)…

  4. Dry Eyes and Glaucoma: Double Trouble

    Science.gov (United States)

    ... Involved News About Us Donate In This Section Dry Eyes and Glaucoma: Double Trouble email Send this article ... eye disease bothers the patient more. What Causes Dry Eye Syndrome? Dry eye can be caused by many ...

  5. Managing eye injuries

    Directory of Open Access Journals (Sweden)

    Dorothy Mutie

    2016-01-01

    Full Text Available Based on what you found during the eye examination, classify the injury as a non-mechanical injury (chemical or thermal injury, a non-globe injury (orbital or adnexal injury or as a mechanical globe injury. In the case of mechanical globe injuries, it is important to classify the injury according to the Birmingham Eye Trauma Terminology System (BETTS and write it down in the patient’s notes; this will help to ensure that everyone involved in caring for the patient will have a consistent understanding of the type of injury. The resulting uniformity of terminology also helps with research, making it possible to compare data and do audits of injuries – which is essential for prevention.

  6. (abstract) ARGOS: a System to Monitor Ulysses Nutation and Thruster Firings from Variations of the Spacecraft Radio Signal

    Science.gov (United States)

    McElrath, T. P.; Cangahuala, L. A.; Miller, K. J.; Stravert, L. R.; Garcia-Perez, Raul

    1995-01-01

    Ulysses is a spin-stabilized spacecraft that experienced significant nutation after its launch in October 1990. This was due to the Sun-spacecraft-Earth geometry, and a study of the phenomenon predicted that the nutation would again be a problem during 1994-95. The difficulty of obtaining nutation estimates in real time from the spacecraft telemetry forced the ESA/NASA Ulysses Team to explore alternative information sources. The work performed by the ESA Operations Team provided a model for a system that uses the radio signal strength measurements to monitor the spacecraft dynamics. These measurements (referred to as AGC) are provided once per second by the tracking stations of the DSN. The system was named ARGOS (Attitude Reckoning from Ground Observable Signals) after the ever-vigilant, hundred-eyed giant of Greek Mythology. The ARGOS design also included Doppler processing, because Doppler shifts indicate thruster firings commanded by the active nutation control carried out onboard the spacecraft. While there is some visibility into thruster activity from telemetry, careful processing of the high-sample-rate Doppler data provides an accurate means of detecting the presence and time of thruster firings. DSN Doppler measurements are available at a ten-per-second rate in the same tracking data block as the AGC data.

  7. Model-based dose calculations for COMS eye plaque brachytherapy using an anatomically realistic eye phantom.

    Science.gov (United States)

    Lesperance, Marielle; Inglis-Whalen, M; Thomson, R M

    2014-02-01

    To investigate the effects of the composition and geometry of ocular media and tissues surrounding the eye on dose distributions for COMS eye plaque brachytherapy with(125)I, (103)Pd, or (131)Cs seeds, and to investigate doses to ocular structures. An anatomically and compositionally realistic voxelized eye model with a medial tumor is developed based on a literature review. Mass energy absorption and attenuation coefficients for ocular media are calculated. Radiation transport and dose deposition are simulated using the EGSnrc Monte Carlo user-code BrachyDose for a fully loaded COMS eye plaque within a water phantom and our full eye model for the three radionuclides. A TG-43 simulation with the same seed configuration in a water phantom neglecting the plaque and interseed effects is also performed. The impact on dose distributions of varying tumor position, as well as tumor and surrounding tissue media is investigated. Each simulation and radionuclide is compared using isodose contours, dose volume histograms for the lens and tumor, maximum, minimum, and average doses to structures of interest, and doses to voxels of interest within the eye. Mass energy absorption and attenuation coefficients of the ocular media differ from those of water by as much as 12% within the 20-30 keV photon energy range. For all radionuclides studied, average doses to the tumor and lens regions in the full eye model differ from those for the plaque in water by 8%-10% and 13%-14%, respectively; the average doses to the tumor and lens regions differ between the full eye model and the TG-43 simulation by 2%-17% and 29%-34%, respectively. Replacing the surrounding tissues in the eye model with water increases the maximum and average doses to the lens by 2% and 3%, respectively. Substituting the tumor medium in the eye model for water, soft tissue, or an alternate melanoma composition affects tumor dose compared to the default eye model simulation by up to 16%. In the full eye model

  8. Model-based dose calculations for COMS eye plaque brachytherapy using an anatomically realistic eye phantom

    International Nuclear Information System (INIS)

    Lesperance, Marielle; Inglis-Whalen, M.; Thomson, R. M.

    2014-01-01

    Purpose : To investigate the effects of the composition and geometry of ocular media and tissues surrounding the eye on dose distributions for COMS eye plaque brachytherapy with 125 I, 103 Pd, or 131 Cs seeds, and to investigate doses to ocular structures. Methods : An anatomically and compositionally realistic voxelized eye model with a medial tumor is developed based on a literature review. Mass energy absorption and attenuation coefficients for ocular media are calculated. Radiation transport and dose deposition are simulated using the EGSnrc Monte Carlo user-code BrachyDose for a fully loaded COMS eye plaque within a water phantom and our full eye model for the three radionuclides. A TG-43 simulation with the same seed configuration in a water phantom neglecting the plaque and interseed effects is also performed. The impact on dose distributions of varying tumor position, as well as tumor and surrounding tissue media is investigated. Each simulation and radionuclide is compared using isodose contours, dose volume histograms for the lens and tumor, maximum, minimum, and average doses to structures of interest, and doses to voxels of interest within the eye. Results : Mass energy absorption and attenuation coefficients of the ocular media differ from those of water by as much as 12% within the 20–30 keV photon energy range. For all radionuclides studied, average doses to the tumor and lens regions in the full eye model differ from those for the plaque in water by 8%–10% and 13%–14%, respectively; the average doses to the tumor and lens regions differ between the full eye model and the TG-43 simulation by 2%–17% and 29%–34%, respectively. Replacing the surrounding tissues in the eye model with water increases the maximum and average doses to the lens by 2% and 3%, respectively. Substituting the tumor medium in the eye model for water, soft tissue, or an alternate melanoma composition affects tumor dose compared to the default eye model simulation by up

  9. The Effect of Golden Pothos in Reducing the Level of Volatile Organic Compounds in a Simulated Spacecraft Cabin

    Science.gov (United States)

    Ursprung, Matthew; Amiri, Azita; Kayatin, Matthew; Perry, Jay

    2016-01-01

    The impact of Golden Pothos on indoor air quality was studied against a simulated spacecraft trace contaminant load model, consistent with the International Space Station (ISS), containing volatile organic compounds (VOCs) and formaldehyde. Previous research provides inconclusive results on the efficacy of plant VOC removal which this projects seeks to rectify through a better experimental design. This work develops a passive system for removing common VOC's from spacecraft and household indoor air and decreasing the necessity for active cabin trace contaminant removal systems.

  10. DOD Recovery personnel and NASA technicians inspect Friendship 7 spacecraft

    Science.gov (United States)

    1964-01-01

    Department of Defense Recovery personnel and spacecraft technicians from NASA adn McDonnell Aircraft Corp., inspect Astronaut John Glenn's Mercury spacecraft, Friendship 7, following its return to Cape Canaveral after recovery in the Atlantic Ocean.

  11. High-Performance Fire Detector for Spacecraft, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The danger from fire aboard spacecraft is immediate with only moments for detection and suppression. Spacecraft are unique high-value systems where the cost of...

  12. Through the creator's eyes

    DEFF Research Database (Denmark)

    Glaveanu, Vlad Petre; Lahlou, Saadi

    2012-01-01

    of an adapted Subjective Evidence-Based Ethnography (SEBE). This methodology combines (a) obtaining first person audio-visual recordings of creative action with a miniature video-camera worn at eye-level, (b) accessing the subjective experience of the participant through a confrontation interview based...... of creativity at both process and content levels. The benefits, limitations, and possible applications of the method are considered in the broader context of creativity studies....

  13. Christoph Scheiner's eye studies.

    Science.gov (United States)

    Daxecker, F

    1992-01-01

    Christoph Scheiner was born in 1573 or 1575. In 1595 he entered into the Order of the Jesuits; he died in 1650. In 1619 his book Oculus, dealing with the optics of the eye, appeared in Innsbruck. The invention of the telescope was of utmost importance for progress in astronomical and physical research. Scheiner himself built telescopes and discovered the sunspots. As a result, an unpleasant priority dispute with Galilei ensued. From 1624 onwards, Scheiner was in Rome, where his main work Rosa Ursina was published in 1630. A part of this book deals with the physiological optics of the eye as well. Some of his discoveries and experiments are taken from these two books: determination of the radius of curvature of the cornea, discovery of the nasal exit of the optic nerve, increase in the radius of curvature of the lens in case of accommodation, Scheiner's procedure (double images with ametropia), refractive indices of various parts of the eye, Scheiner's experiment. Without any doubt, Christoph Scheiner belongs to the foremost scientists of the first half of the 17th century.

  14. Comprehensive eye evaluation algorithm

    Science.gov (United States)

    Agurto, C.; Nemeth, S.; Zamora, G.; Vahtel, M.; Soliz, P.; Barriga, S.

    2016-03-01

    In recent years, several research groups have developed automatic algorithms to detect diabetic retinopathy (DR) in individuals with diabetes (DM), using digital retinal images. Studies have indicated that diabetics have 1.5 times the annual risk of developing primary open angle glaucoma (POAG) as do people without DM. Moreover, DM patients have 1.8 times the risk for age-related macular degeneration (AMD). Although numerous investigators are developing automatic DR detection algorithms, there have been few successful efforts to create an automatic algorithm that can detect other ocular diseases, such as POAG and AMD. Consequently, our aim in the current study was to develop a comprehensive eye evaluation algorithm that not only detects DR in retinal images, but also automatically identifies glaucoma suspects and AMD by integrating other personal medical information with the retinal features. The proposed system is fully automatic and provides the likelihood of each of the three eye disease. The system was evaluated in two datasets of 104 and 88 diabetic cases. For each eye, we used two non-mydriatic digital color fundus photographs (macula and optic disc centered) and, when available, information about age, duration of diabetes, cataracts, hypertension, gender, and laboratory data. Our results show that the combination of multimodal features can increase the AUC by up to 5%, 7%, and 8% in the detection of AMD, DR, and glaucoma respectively. Marked improvement was achieved when laboratory results were combined with retinal image features.

  15. Pax genes in eye development and evolution

    Czech Academy of Sciences Publication Activity Database

    Kozmik, Zbyněk

    2005-01-01

    Roč. 15, č. 4 (2005), s. 430-438 ISSN 0959-437X R&D Projects: GA MŠk(CZ) 1M0520; GA ČR(CZ) GA204/04/1358 Institutional research plan: CEZ:AV0Z5052915 Keywords : paxpax * eye development * evolution Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 9.361, year: 2005

  16. Space tribology: its role in spacecraft mechanisms

    International Nuclear Information System (INIS)

    Roberts, E W

    2012-01-01

    The subject of tribology encompasses the friction, wear and lubrication of mechanical components such as bearings and gears. Tribological practices are aimed at ensuring that such components operate with high efficiency (low friction) and achieve long lives. On spacecraft mechanisms the route to achieving these goals brings its own unique challenges. This review describes the problems posed by the space environment, the types of tribological component used on spacecraft and the approaches taken to their lubrication. It is shown that in many instances lubrication needs can be met by synthetic oils having exceedingly low volatilities, but that at temperature extremes the only means of reducing friction and wear is by solid lubrication. As the demands placed on space engineering increase, innovatory approaches will be needed to solve future tribological problems. The direction that future developments might take is anticipated and discussed.

  17. MIDN: A spacecraft Micro-dosimeter mission

    International Nuclear Information System (INIS)

    Pisacane, V. L.; Ziegler, J. F.; Nelson, M. E.; Caylor, M.; Flake, D.; Heyen, L.; Youngborg, E.; Rosenfeld, A. B.; Cucinotta, F.; Zaider, M.; Dicello, J. F.

    2006-01-01

    MIDN (Micro-dosimetry instrument) is a payload on the MidSTAR-I spacecraft (Midshipman Space Technology Applications Research) under development at the United States Naval Academy. MIDN is a solid-state system being designed and constructed to measure Micro-dosimetric spectra to determine radiation quality factors for space environments. Radiation is a critical threat to the health of astronauts and to the success of missions in low-Earth orbit and space exploration. The system will consist of three separate sensors, one external to the spacecraft, one internal and one embedded in polyethylene. Design goals are mass <3 kg and power <2 W. The MidSTAR-I mission in 2006 will provide an opportunity to evaluate a preliminary version of this system. Its low power and mass makes it useful for the International Space Station and manned and unmanned interplanetary missions as a real-time system to assess and alert astronauts to enhanced radiation environments. (authors)

  18. Galileo spacecraft power management and distribution system

    International Nuclear Information System (INIS)

    Detwiler, R.C.; Smith, R.L.

    1990-01-01

    It has been twelve years since two Voyager spacecraft began the direct route to the outer planets. In October 1989 a single Galileo spacecraft started the return to Jupiter. Conceived as a simple Voyager look-alike, the Galileo power management and distribution (PMAD) system has undergone many iterations in configuration. Major changes to the PMAD resulted from dual spun slip ring limitations, variations in launch vehicle thrust capabilities, and launch delays. Lack of an adequate launch vehicle for an interplanetary mission of Galileo's size has resulted in an extremely long flight duration. A Venus-Earth-Earth Gravity Assist (VEEGA) tour, vital to attain the required energy, results in a 6 year trip to Jupiter and its moons. This paper provides a description of the Galileo PMAD and documents the design drivers that established the final as-built hardware

  19. Improved techniques for predicting spacecraft power

    International Nuclear Information System (INIS)

    Chmielewski, A.B.

    1987-01-01

    Radioisotope Thermoelectric Generators (RTGs) are going to supply power for the NASA Galileo and Ulysses spacecraft now scheduled to be launched in 1989 and 1990. The duration of the Galileo mission is expected to be over 8 years. This brings the total RTG lifetime to 13 years. In 13 years, the RTG power drops more than 20 percent leaving a very small power margin over what is consumed by the spacecraft. Thus it is very important to accurately predict the RTG performance and be able to assess the magnitude of errors involved. The paper lists all the error sources involved in the RTG power predictions and describes a statistical method for calculating the tolerance

  20. Data combinations accounting for LISA spacecraft motion

    International Nuclear Information System (INIS)

    Shaddock, Daniel A.; Tinto, Massimo; Estabrook, Frank B.; Armstrong, J.W.

    2003-01-01

    The laser interferometer space antenna is an array of three spacecraft in an approximately equilateral triangle configuration which will be used as a low-frequency gravitational wave detector. We present here new generalizations of the Michelson- and Sagnac-type time-delay interferometry data combinations. These combinations cancel laser phase noise in the presence of different up and down propagation delays in each arm of the array, and slowly varying systematic motion of the spacecraft. The gravitational wave sensitivities of these generalized combinations are the same as previously computed for the stationary cases, although the combinations are now more complicated. We introduce a diagrammatic representation to illustrate that these combinations are actually synthesized equal-arm interferometers

  1. The Stardust spacecraft arrives at KSC

    Science.gov (United States)

    1998-01-01

    After arrival at the Shuttle Landing Facility in the early morning hours, the crated Stardust spacecraft waits to be unloaded from the aircraft. Built by Lockheed Martin Astronautics near Denver, Colo., for the Jet Propulsion Laboratory (JPL) NASA, the spacecraft Stardust will use a unique medium called aerogel to capture comet particles flying off the nucleus of comet Wild 2 in January 2004, plus collect interstellar dust for later analysis. Stardust will be launched aboard a Boeing Delta 7426 rocket from Complex 17, Cape Canaveral Air Station, targeted for Feb. 6, 1999. The collected samples will return to Earth in a re- entry capsule to be jettisoned from Stardust as it swings by in January 2006.

  2. Close-Range Photogrammetry & Next Generation Spacecraft

    Science.gov (United States)

    Pappa, Richard S.

    2002-01-01

    NASA is focusing renewed attention on the topic of large, ultra-lightweight space structures, also known as 'gossamer' spacecraft. Nearly all of the details of the giant spacecraft are still to be worked out. But it's already clear that one of the most challenging aspects will be developing techniques to align and control these systems after they are deployed in space. A critical part of this process is creating new ground test methods to measure gossamer structures under stationary, deploying and vibrating conditions for validation of corresponding analytical predictions. In addressing this problem, I considered, first of all, the possibility of simply using conventional displacement or vibration sensor that could provide spatial measurements. Next, I turned my attention to photogrammetry, a method of determining the spatial coordinates of objects using photographs. The success of this research and development has convinced me that photogrammetry is the most suitable method to solve the gossamer measurement problem.

  3. Large Scale Experiments on Spacecraft Fire Safety

    DEFF Research Database (Denmark)

    Urban, David L.; Ruff, Gary A.; Minster, Olivier

    2012-01-01

    -based microgravity facilities or has been limited to very small fuel samples. Still, the work conducted to date has shown that fire behaviour in low-gravity is very different from that in normal-gravity, with differences observed for flammability limits, ignition delay, flame spread behaviour, flame colour and flame......Full scale fire testing complemented by computer modelling has provided significant knowhow about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due...... to the complexity, cost and risk associ-ated with operating a long duration fire safety experiment of a relevant size in microgravity. Therefore, there is currently a gap in knowledge of fire behaviour in spacecraft. The entire body of low-gravity fire research has either been conducted in short duration ground...

  4. FORTE spacecraft vibration mitigation. Final report

    International Nuclear Information System (INIS)

    Maly, J.R.

    1996-02-01

    This report documents work that was performed by CSA Engineering, Inc., for Los Alamos National Laboratory (LANL), to reduce vibrations of the FORTE spacecraft by retrofitting damped structural components into the spacecraft structure. The technical objective of the work was reduction of response at the location of payload components when the structure is subjected to the dynamic loading associated with launch and proto-qualification testing. FORTE is a small satellite that will be placed in orbit in 1996. The structure weighs approximately 425 lb, and is roughly 80 inches high and 40 inches in diameter. It was developed and built by LANL in conjunction with Sandia National Laboratories Albuquerque for the United States Department of Energy. The FORTE primary structure was fabricated primarily with graphite epoxy, using aluminum honeycomb core material for equipment decks and solar panel substrates. Equipment decks were bonded and bolted through aluminum mounting blocks to adjoining structure

  5. Eye movement perimetry in glaucoma.

    Science.gov (United States)

    Trope, G E; Eizenman, M; Coyle, E

    1989-08-01

    Present-day computerized perimetry is often inaccurate and unreliable owing to the need to maintain central fixation over long periods while repressing the normal response to presentation of peripheral stimuli. We tested a new method of perimetry that does not require prolonged central fixation. During this test eye movements were encouraged on presentation of a peripheral target. Twenty-three eyes were studied with an Octopus perimeter, with a technician monitoring eye movements. The sensitivity was 100% and the specificity 23%. The low specificity was due to the technician's inability to accurately monitor small eye movements in the central 6 degrees field. If small eye movements are monitored accurately with an eye tracker, eye movement perimetry could become an alternative method to standard perimetry.

  6. Redundancy for electric motors in spacecraft applications

    Science.gov (United States)

    Smith, Robert J.; Flew, Alastair R.

    1986-01-01

    The parts of electric motors which should be duplicated in order to provide maximum reliability in spacecraft application are identified. Various common types of redundancy are described. The advantages and disadvantages of each are noted. The principal types are illustrated by reference to specific examples. For each example, constructional details, basic performance data and failure modes are described, together with a discussion of the suitability of particular redundancy techniques to motor types.

  7. Research on spacecraft electrical power conversion

    Science.gov (United States)

    Wilson, T. G.

    1983-01-01

    The history of spacecraft electrical power conversion in literature, research and practice is reviewed. It is noted that the design techniques, analyses and understanding which were developed make today's contribution to power computers and communication installations. New applications which require more power, improved dynamic response, greater reliability, and lower cost are outlined. The switching mode approach in electronic power conditioning is discussed. Technical aspects of the research are summarized.

  8. Schema for Spacecraft-Command Dictionary

    Science.gov (United States)

    Laubach, Sharon; Garcia, Celina; Maxwell, Scott; Wright, Jesse

    2008-01-01

    An Extensible Markup Language (XML) schema was developed as a means of defining and describing a structure for capturing spacecraft command- definition and tracking information in a single location in a form readable by both engineers and software used to generate software for flight and ground systems. A structure defined within this schema is then used as the basis for creating an XML file that contains command definitions.

  9. Additive Manufacturing: Ensuring Quality for Spacecraft Applications

    Science.gov (United States)

    Swanson, Theodore; Stephenson, Timothy

    2014-01-01

    Reliable manufacturing requires that material properties and fabrication processes be well defined in order to insure that the manufactured parts meet specified requirements. While this issue is now relatively straightforward for traditional processes such as subtractive manufacturing and injection molding, this capability is still evolving for AM products. Hence, one of the principal challenges within AM is in qualifying and verifying source material properties and process control. This issue is particularly critical for applications in harsh environments and demanding applications, such as spacecraft.

  10. Wheel speed management control system for spacecraft

    Science.gov (United States)

    Goodzeit, Neil E. (Inventor); Linder, David M. (Inventor)

    1991-01-01

    A spacecraft attitude control system uses at least four reaction wheels. In order to minimize reaction wheel speed and therefore power, a wheel speed management system is provided. The management system monitors the wheel speeds and generates a wheel speed error vector. The error vector is integrated, and the error vector and its integral are combined to form a correction vector. The correction vector is summed with the attitude control torque command signals for driving the reaction wheels.

  11. The Manned Spacecraft Center and medical technology

    Science.gov (United States)

    Johnston, R. S.; Pool, S. L.

    1974-01-01

    A number of medically oriented research and hardware development programs in support of manned space flights have been sponsored by NASA. Blood pressure measuring systems for use in spacecraft are considered. In some cases, complete new bioinstrumentation systems were necessary to accomplish a specific physiological study. Plans for medical research during the Skylab program are discussed along with general questions regarding space-borne health service systems and details concerning the Health Services Support Control Center.

  12. Artificial Intelligence and Spacecraft Power Systems

    Science.gov (United States)

    Dugel-Whitehead, Norma R.

    1997-01-01

    This talk will present the work which has been done at NASA Marshall Space Flight Center involving the use of Artificial Intelligence to control the power system in a spacecraft. The presentation will include a brief history of power system automation, and some basic definitions of the types of artificial intelligence which have been investigated at MSFC for power system automation. A video tape of one of our autonomous power systems using co-operating expert systems, and advanced hardware will be presented.

  13. THE FUTURE OF SPACECRAFT NUCLEAR PROPULSION

    OpenAIRE

    Jansen, Frank

    2014-01-01

    This paper summarizes the advantages of space nuclear power and propulsion systems. It describes the actual status of international power level dependent spacecraft nuclear propulsion missions, especially the high power EU-Russian MEGAHIT study including the Russian Megawatt-Class Nuclear Power Propulsion System, the NASA GRC project and the low and medium power EU DiPoP study. Space nuclear propulsion based mission scenarios of these studies are sketched as well.

  14. Spacecraft early design validation using formal methods

    International Nuclear Information System (INIS)

    Bozzano, Marco; Cimatti, Alessandro; Katoen, Joost-Pieter; Katsaros, Panagiotis; Mokos, Konstantinos; Nguyen, Viet Yen; Noll, Thomas; Postma, Bart; Roveri, Marco

    2014-01-01

    The size and complexity of software in spacecraft is increasing exponentially, and this trend complicates its validation within the context of the overall spacecraft system. Current validation methods are labor-intensive as they rely on manual analysis, review and inspection. For future space missions, we developed – with challenging requirements from the European space industry – a novel modeling language and toolset for a (semi-)automated validation approach. Our modeling language is a dialect of AADL and enables engineers to express the system, the software, and their reliability aspects. The COMPASS toolset utilizes state-of-the-art model checking techniques, both qualitative and probabilistic, for the analysis of requirements related to functional correctness, safety, dependability and performance. Several pilot projects have been performed by industry, with two of them having focused on the system-level of a satellite platform in development. Our efforts resulted in a significant advancement of validating spacecraft designs from several perspectives, using a single integrated system model. The associated technology readiness level increased from level 1 (basic concepts and ideas) to early level 4 (laboratory-tested)

  15. Determination of Realistic Fire Scenarios in Spacecraft

    Science.gov (United States)

    Dietrich, Daniel L.; Ruff, Gary A.; Urban, David

    2013-01-01

    This paper expands on previous work that examined how large a fire a crew member could successfully survive and extinguish in the confines of a spacecraft. The hazards to the crew and equipment during an accidental fire include excessive pressure rise resulting in a catastrophic rupture of the vehicle skin, excessive temperatures that burn or incapacitate the crew (due to hyperthermia), carbon dioxide build-up or accumulation of other combustion products (e.g. carbon monoxide). The previous work introduced a simplified model that treated the fire primarily as a source of heat and combustion products and sink for oxygen prescribed (input to the model) based on terrestrial standards. The model further treated the spacecraft as a closed system with no capability to vent to the vacuum of space. The model in the present work extends this analysis to more realistically treat the pressure relief system(s) of the spacecraft, include more combustion products (e.g. HF) in the analysis and attempt to predict the fire spread and limiting fire size (based on knowledge of terrestrial fires and the known characteristics of microgravity fires) rather than prescribe them in the analysis. Including the characteristics of vehicle pressure relief systems has a dramatic mitigating effect by eliminating vehicle overpressure for all but very large fires and reducing average gas-phase temperatures.

  16. Probing interferometric parallax with interplanetary spacecraft

    Science.gov (United States)

    Rodeghiero, G.; Gini, F.; Marchili, N.; Jain, P.; Ralston, J. P.; Dallacasa, D.; Naletto, G.; Possenti, A.; Barbieri, C.; Franceschini, A.; Zampieri, L.

    2017-07-01

    We describe an experimental scenario for testing a novel method to measure distance and proper motion of astronomical sources. The method is based on multi-epoch observations of amplitude or intensity correlations between separate receiving systems. This technique is called Interferometric Parallax, and efficiently exploits phase information that has traditionally been overlooked. The test case we discuss combines amplitude correlations of signals from deep space interplanetary spacecraft with those from distant galactic and extragalactic radio sources with the goal of estimating the interplanetary spacecraft distance. Interferometric parallax relies on the detection of wavefront curvature effects in signals collected by pairs of separate receiving systems. The method shows promising potentialities over current techniques when the target is unresolved from the background reference sources. Developments in this field might lead to the construction of an independent, geometrical cosmic distance ladder using a dedicated project and future generation instruments. We present a conceptual overview supported by numerical estimates of its performances applied to a spacecraft orbiting the Solar System. Simulations support the feasibility of measurements with a simple and time-saving observational scheme using current facilities.

  17. On-orbit supervisor for controlling spacecraft

    Science.gov (United States)

    Vandervoort, Richard J.

    1992-07-01

    Spacecraft systems of the 1990's and beyond will be substantially more complex than their predecessors. They will have demanding performance requirements and will be expected to operate more autonomously. This underscores the need for innovative approaches to Fault Detection, Isolation and Recovery (FDIR). A hierarchical expert system is presented that provides on-orbit supervision using intelligent FDIR techniques. Each expert system in the hierarchy supervises the operation of a local set of spacecraft functions. Spacecraft operational goals flow top down while responses flow bottom up. The expert system supervisors have a fairly high degree of autonomy. Bureaucratic responsibilities are minimized to conserve bandwidth and maximize response time. Data for FDIR can be acquired local to an expert and from other experts. By using a blackboard architecture for each supervisor, the system provides a great degree of flexibility in implementing the problem solvers for each problem domain. In addition, it provides for a clear separation between facts and knowledge, leading to an efficient system capable of real time response.

  18. Delamination Assessment Tool for Spacecraft Composite Structures

    Science.gov (United States)

    Portela, Pedro; Preller, Fabian; Wittke, Henrik; Sinnema, Gerben; Camanho, Pedro; Turon, Albert

    2012-07-01

    Fortunately only few cases are known where failure of spacecraft structures due to undetected damage has resulted in a loss of spacecraft and launcher mission. However, several problems related to damage tolerance and in particular delamination of composite materials have been encountered during structure development of various ESA projects and qualification testing. To avoid such costly failures during development, launch or service of spacecraft, launcher and reusable launch vehicles structures a comprehensive damage tolerance verification approach is needed. In 2009, the European Space Agency (ESA) initiated an activity called “Delamination Assessment Tool” which is led by the Portuguese company HPS Lda and includes academic and industrial partners. The goal of this study is the development of a comprehensive damage tolerance verification approach for launcher and reusable launch vehicles (RLV) structures, addressing analytical and numerical methodologies, material-, subcomponent- and component testing, as well as non-destructive inspection. The study includes a comprehensive review of current industrial damage tolerance practice resulting from ECSS and NASA standards, the development of new Best Practice Guidelines for analysis, test and inspection methods and the validation of these with a real industrial case study. The paper describes the main findings of this activity so far and presents a first iteration of a Damage Tolerance Verification Approach, which includes the introduction of novel analytical and numerical tools at an industrial level. This new approach is being put to the test using real industrial case studies provided by the industrial partners, MT Aerospace, RUAG Space and INVENT GmbH

  19. Which lamp will be optimum to eye? Incandescent, fluorescent or LED etc

    Directory of Open Access Journals (Sweden)

    Liang Chen

    2014-02-01

    Full Text Available Low frequency flicker, high frequency flicker, strong light, strong blue light, infrared, ultraviolet, electromagnetic radiation, ripple flicker and dimming flicker produced by different lamps have negative impact on vision, eyes and health. Negative impact on eyes resulting in myopia or cataract etc:the solution is to remove all the negative factors by applying upright lighting technology and that is optimum to vision, eyes and health.

  20. Eye trauma in Laurel and Hardy movies - another nice mess.

    Science.gov (United States)

    Zegers, Lara DA; Zegers, Richard Hc

    2016-11-01

    One of the characteristics in Laurel and Hardy films is a lot of physical violence. The present study examines the occurrence of eye trauma in Laurel and Hardy movies and discusses the impact they could have been had if the films were set in reality. All 92 movies starring Laurel and Hardy as a pair in leading roles were watched together by the authors and were scored for any eye trauma. Eighty-eight eye traumas happened, of which 48% were directed at Hardy. The eye poke was the most frequently occurring eye trauma and the traumatic corneal abrasion was very likely the most frequently occurring injury. Among the most serious causes of eye trauma were the pin of a door handle, a stick, a champagne cork, a tree branch and tacks. Without a doubt, if their films had been reality, especially Hardy but also Laurel and several other people, would have suffered from serious eye injuries caused by the 88 eye traumas. The findings of the present study might reflect the personality, character and intellectual capacity of both Laurel and Hardy as 'Two Minds Without a Single Thought'. © The Author(s) 2016.

  1. The Effect of Eye Contact Is Contingent on Visual Awareness

    Directory of Open Access Journals (Sweden)

    Shan Xu

    2018-02-01

    Full Text Available The present study explored how eye contact at different levels of visual awareness influences gaze-induced joint attention. We adopted a spatial-cueing paradigm, in which an averted gaze was used as an uninformative central cue for a joint-attention task. Prior to the onset of the averted-gaze cue, either supraliminal (Experiment 1 or subliminal (Experiment 2 eye contact was presented. The results revealed a larger subsequent gaze-cueing effect following supraliminal eye contact compared to a no-contact condition. In contrast, the gaze-cueing effect was smaller in the subliminal eye-contact condition than in the no-contact condition. These findings suggest that the facilitation effect of eye contact on coordinating social attention depends on visual awareness. Furthermore, subliminal eye contact might have an impact on subsequent social attention processes that differ from supraliminal eye contact. This study highlights the need to further investigate the role of eye contact in implicit social cognition.

  2. System and Method for Eye Tracking

    DEFF Research Database (Denmark)

    2017-01-01

    A method and system for monitoring the motion of one or both eyes, includes capturing a sequence of overlapping images of a subject's face including an eye and the corresponding non-eye region; identifying a plurality of keypoints in each image; mapping corresponding keypoints in two or more images...... of the sequence; assigning the keypoints to the eye and to the corresponding non-eye region; calculating individual velocities of the corresponding keypoints in the eye and the corresponding non-eye region to obtain a distribution of velocities; extracting at least one velocity measured for the eye and at least...... one velocity measured for the corresponding non-eye region; calculating the eye-in-head velocity for the eye based upon the measured velocity for the eye and the measured velocity for the corresponding non-eye region; and calculating the eye-in-head position based upon the eye- in-head velocity....

  3. Ethical Issues in Transnational Eye Banking.

    Science.gov (United States)

    Martin, Dominique E; Kelly, Richard; Jones, Gary L A; Machin, Heather; Pollock, Graeme A

    2017-02-01

    To review ethical issues that may arise in the setting of transnational eye banking activities, such as when exporting or importing corneal tissue for transplantation. A principle-based normative analysis of potential common dilemmas in transnational eye banking activities was performed. Transnational activities in eye banking, like those in other fields involving procurement and use of medical products of human origin, may present a number of ethical issues for policy makers and professionals. Key ethical concerns include the potential impact of export or import activities on self-sufficiency of corneal tissue supply within exporting and importing countries; potential disclosure requirements when obtaining consent or authorization for ocular tissue donation when donations may be exported; and difficulties inherent in assuring equity in the allocation of tissues available for export and in establishing and respecting standards of safety and quality across different jurisdictions. Further analysis of specific ethical issues in eye banking is necessary to inform development of guidelines and other governance tools that will assist policy makers and professionals to support ethical practice.

  4. Space Environments and Spacecraft Effects Organization Concept

    Science.gov (United States)

    Edwards, David L.; Burns, Howard D.; Miller, Sharon K.; Porter, Ron; Schneider, Todd A.; Spann, James F.; Xapsos, Michael

    2012-01-01

    The National Aeronautics and Space Administration (NASA) is embarking on a course to expand human presence beyond Low Earth Orbit (LEO) while also expanding its mission to explore the solar system. Destinations such as Near Earth Asteroids (NEA), Mars and its moons, and the outer planets are but a few of the mission targets. Each new destination presents an opportunity to increase our knowledge of the solar system and the unique environments for each mission target. NASA has multiple technical and science discipline areas specializing in specific space environments disciplines that will help serve to enable these missions. To complement these existing discipline areas, a concept is presented focusing on the development of a space environments and spacecraft effects (SENSE) organization. This SENSE organization includes disciplines such as space climate, space weather, natural and induced space environments, effects on spacecraft materials and systems and the transition of research information into application. This space environment and spacecraft effects organization will be composed of Technical Working Groups (TWG). These technical working groups will survey customers and users, generate products, and provide knowledge supporting four functional areas: design environments, engineering effects, operational support, and programmatic support. The four functional areas align with phases in the program mission lifecycle and are briefly described below. Design environments are used primarily in the mission concept and design phases of a program. Engineering effects focuses on the material, component, sub-system and system-level selection and the testing to verify design and operational performance. Operational support provides products based on real time or near real time space weather to mission operators to aid in real time and near-term decision-making. The programmatic support function maintains an interface with the numerous programs within NASA, other federal

  5. Large Scale Experiments on Spacecraft Fire Safety

    Science.gov (United States)

    Urban, David; Ruff, Gary A.; Minster, Olivier; Fernandez-Pello, A. Carlos; Tien, James S.; Torero, Jose L.; Legros, Guillaume; Eigenbrod, Christian; Smirnov, Nickolay; Fujita, Osamu; hide

    2012-01-01

    Full scale fire testing complemented by computer modelling has provided significant knowhow about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due to the complexity, cost and risk associated with operating a long duration fire safety experiment of a relevant size in microgravity. Therefore, there is currently a gap in knowledge of fire behaviour in spacecraft. The entire body of low-gravity fire research has either been conducted in short duration ground-based microgravity facilities or has been limited to very small fuel samples. Still, the work conducted to date has shown that fire behaviour in low-gravity is very different from that in normal gravity, with differences observed for flammability limits, ignition delay, flame spread behaviour, flame colour and flame structure. As a result, the prediction of the behaviour of fires in reduced gravity is at present not validated. To address this gap in knowledge, a collaborative international project, Spacecraft Fire Safety, has been established with its cornerstone being the development of an experiment (Fire Safety 1) to be conducted on an ISS resupply vehicle, such as the Automated Transfer Vehicle (ATV) or Orbital Cygnus after it leaves the ISS and before it enters the atmosphere. A computer modelling effort will complement the experimental effort. Although the experiment will need to meet rigorous safety requirements to ensure the carrier vehicle does not sustain damage, the absence of a crew removes the need for strict containment of combustion products. This will facilitate the possibility of examining fire behaviour on a scale that is relevant to spacecraft fire safety and will provide unique data for fire model validation. This unprecedented opportunity will expand the understanding of the fundamentals of fire behaviour in spacecraft. The experiment is being

  6. Topology Optimization of Spacecraft Transfer Compartment

    Directory of Open Access Journals (Sweden)

    A. A. Borovikov

    2016-01-01

    Full Text Available IntroductionThe subject of this research is topology optimization of the adapter of a spacecraft transfer compartment. The finite element topology optimization [1] is widely used for simple structure elements [6, 7]. It is argued that using this method in conjunction with additive technology (3D - printing it is possible to create construction designs with the best weight characteristics. However, the paper shows that when applying this method to a complex construction design the optimization results are highly sensitive to optimization algorithm parameters. The goal of this research is to study parameters of the topology optimization algorithm and the influence of their variations on results.1.      Problem formulation   A commercial software Altair HyperWorks/OptiStruct (student’s license performed numerical calculations. The paper presents a detailed description of the finite element model.The main features of the proposed model are as follows:-          Simplicity with non-complicated geometry;-          Building a finite element model in terms of computing time minimization;-          Using the lumped mass elements to simulate the impacts of the conjugates on the adapter;-          A limit of material strength, decreased by an order of magnitude, to eliminate stress concentrators;-          The gravitational load applied corresponds to the loads for the Angara-A5 launcher [8]. 2.      Method of solutionA brief description of the SIMP-method realized in the Altair HyperWorks/OptiStruct software is given.3.      ResultsPerformed numerical calculations, and shown the influence of variations of algorithm parameters (DISCRETE, MATINIT, MINDIM, MAXDIM on construction design as well as the parameters SINGLE and SPLIT used to reveal restrictions on manufacturing.Shown that, depending on variations of parameters, an adapter construction strives to «truss» or «shell» type. Described

  7. The application of autologous serum eye drops in severe dry eye patients; subjective and objective parameters before and after treatment.

    Science.gov (United States)

    Jirsova, Katerina; Brejchova, Kristyna; Krabcova, Ivana; Filipec, Martin; Al Fakih, Aref; Palos, Michalis; Vesela, Viera

    2014-01-01

    To assess the impact of autologous serum (AS) eye drops on the ocular surface of patients with bilateral severe dry eye and to draw a comparison between the clinical and laboratory examinations and the degree of subjective symptoms before and after serum treatment. A three-month prospective study was conducted on 17 patients with severe dry eye. AS eye drops were applied a maximum of 12 times a day together with regular therapy. Dry eye status was evaluated by clinical examination (visual acuity, Schirmer test, tear film breakup time, vital staining, tear film debris and meniscus), conjunctival impression cytology (epithelial and goblet cell density, snake-like chromatin, HLA-DR-positive and apoptotic cells) and subjectively by the patients. The application of AS eye drops led to a significant improvement in the Schirmer test (p treatment. A significant decrease (p eyes. We found that three-month AS treatment led especially to the improvement of ocular surface dryness and damage of the epithelium. The improvement of dry eye after AS treatment correlated well with the clinical, laboratory and subjective findings. From the patients' subjective point of view, the positive effect of AS decreased with time, but still persisted up to three months after the end of therapy.

  8. Contemporary state of spacecraft/environment interaction research

    CERN Document Server

    Novikov, L S

    1999-01-01

    Various space environment effects on spacecraft materials and equipment, and the reverse effects of spacecrafts and rockets on space environment are considered. The necessity of permanent updating and perfection of our knowledge on spacecraft/environment interaction processes is noted. Requirements imposed on models of space environment in theoretical and experimental researches of various aspects of the spacecraft/environment interaction problem are formulated. In this field, main problems which need to be solved today and in the nearest future are specified. The conclusion is made that the joint analysis of both aspects of spacecraft/environment interaction problem promotes the most effective solution of the problem.

  9. Spacecraft Charging: Hazard Causes, Hazard Effects, Hazard Controls

    Science.gov (United States)

    Koontz, Steve.

    2018-01-01

    Spacecraft flight environments are characterized both by a wide range of space plasma conditions and by ionizing radiation (IR), solar ultraviolet and X-rays, magnetic fields, micrometeoroids, orbital debris, and other environmental factors, all of which can affect spacecraft performance. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of spacecraft charging and charging effects that can be applied to solving practical spacecraft and spacesuit engineering design, verification, and operations problems, with an emphasis on spacecraft operations in low-Earth orbit, Earth's magnetosphere, and cis-Lunar space.

  10. Electronic Systems for Spacecraft Vehicles: Required EDA Tools

    Science.gov (United States)

    Bachnak, Rafic

    1999-01-01

    The continuous increase in complexity of electronic systems is making the design and manufacturing of such systems more challenging than ever before. As a result, designers are finding it impossible to design efficient systems without the use of sophisticated Electronic Design Automation (EDA) tools. These tools offer integrated simulation of the electrical, mechanical, and manufacturing functions and lead to a correct by design methodology. This report identifies the EDA tools that would be needed to design, analyze, simulate, and evaluate electronic systems for spacecraft vehicles. In addition, the report presents recommendations to enhance the current JSC electronic design capabilities. This includes cost information and a discussion as to the impact, both positive and negative, of implementing the recommendations.

  11. Intelligent data management for real-time spacecraft monitoring

    Science.gov (United States)

    Schwuttke, Ursula M.; Gasser, Les; Abramson, Bruce

    1992-01-01

    Real-time AI systems have begun to address the challenge of restructuring problem solving to meet real-time constraints by making key trade-offs that pursue less than optimal strategies with minimal impact on system goals. Several approaches for adapting to dynamic changes in system operating conditions are known. However, simultaneously adapting system decision criteria in a principled way has been difficult. Towards this end, a general technique for dynamically making such trade-offs using a combination of decision theory and domain knowledge has been developed. Multi-attribute utility theory (MAUT), a decision theoretic approach for making one-time decisions is discussed and dynamic trade-off evaluation is described as a knowledge-based extension of MAUT that is suitable for highly dynamic real-time environments, and provides an example of dynamic trade-off evaluation applied to a specific data management trade-off in a real-world spacecraft monitoring application.

  12. Efficacy of corneal eye shields in protecting patients' eyes from laser irradiation.

    Science.gov (United States)

    Russell, S W; Dinehart, S M; Davis, I; Flock, S T

    1996-07-01

    The continuing development of new types and applications of lasers has appeared to surpass the development of specific eye protection for these lasers. There are a variety of eye shields on the market, but few are specifically designed for laser protection. Our purpose was to test a variety of eye shields by two parameters, light transmission and temperature rise, and to determine from these measurements the most protective shield for patients. We tested four plastic shields, one metal shield, and two sets of tanning goggles for temperature rise and light transmission when irradiated with a beam from a flashlamp-pumped, pulsed-dye laser. The temperature rise at the surface of the shield opposite the laser impacts was no more than 0.2 degree C in any case. White light was transmitted at significant levels through several of the shields, but yellow light transmittance was noted only through the green eye shield. Our measurements indicate that all except the green shield appeared safe from transmission of the 585-nm radiant energy. However, the optimal laser eye shield, in our opinion, would be a composite of several different shields' characteristics.

  13. With eyes wide open

    DEFF Research Database (Denmark)

    Frølunde, Lisbeth; Pedersen, Chistina Hee

    2013-01-01

    and that vulnerability and discomfort are often overlooked as transformative forces. The analysis draws on data from a classroom context in which university students tested methods for facilitating creative thinking in a course on data production and creativity. The data stem from a session on the method “Lego Serious...... in constructions of group identity when an external facilitator disrupts a context. We argue that the facilitation of creative methods calls for keeping our eyes wide open for tensions, for they are the mulch that improves the soil....

  14. Eye trauma in boxing.

    Science.gov (United States)

    Corrales, Gustavo; Curreri, Anthony

    2009-10-01

    In boxing, along with a few other sports, trauma is inherent to the nature of the sport; therefore it is considered a high-risk sport for ocular injuries. The long-term morbidity of ocular injuries suffered by boxers is difficult to estimate due to the lack of structured long-term follow-up of these athletes. Complications of blunt ocular trauma may develop years after the athlete has retired from the ring and is no longer considered to be at risk for boxing-related injuries. This article describes the wide range of eye injuries a boxer can sustain, and their immediate and long-term clinical management.

  15. SHARP - Automated monitoring of spacecraft health and status

    Science.gov (United States)

    Atkinson, David J.; James, Mark L.; Martin, R. G.

    1990-01-01

    Briefly discussed here are the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory (JPL). Some of the difficulties associated with the existing technology used in mission operations are highlighted. A new automated system based on artificial intelligence technology is described which seeks to overcome many of these limitations. The system, called the Spacecraft Health Automated Reasoning Prototype (SHARP), is designed to automate health and status analysis for multi-mission spacecraft and ground data systems operations. The system has proved to be effective for detecting and analyzing potential spacecraft and ground systems problems by performing real-time analysis of spacecraft and ground data systems engineering telemetry. Telecommunications link analysis of the Voyager 2 spacecraft was the initial focus for evaluation of the system in real-time operations during the Voyager spacecraft encounter with Neptune in August 1989.

  16. SHARP: Automated monitoring of spacecraft health and status

    Science.gov (United States)

    Atkinson, David J.; James, Mark L.; Martin, R. Gaius

    1991-01-01

    Briefly discussed here are the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory (JPL). Some of the difficulties associated with the existing technology used in mission operations are highlighted. A new automated system based on artificial intelligence technology is described which seeks to overcome many of these limitations. The system, called the Spacecraft Health Automated Reasoning Prototype (SHARP), is designed to automate health and status analysis for multi-mission spacecraft and ground data systems operations. The system has proved to be effective for detecting and analyzing potential spacecraft and ground systems problems by performing real-time analysis of spacecraft and ground data systems engineering telemetry. Telecommunications link analysis of the Voyager 2 spacecraft was the initial focus for evaluation of the system in real-time operations during the Voyager spacecraft encounter with Neptune in August 1989.

  17. Impact spacecraft imagery and comparative morphology of craters

    International Nuclear Information System (INIS)

    Moutsoulas, M.; Piteri, S.

    1979-01-01

    The use of hard-landing 'simple' missions for wide-scale planetary exploration is considered. As an example of their imagery potentialities, Ranger VII data are used for the study of the morphological characteristics of 16 Mare Cognitum craters. The morphological patterns of lunar craters, expressed in terms of the Depth/Diameter ratios appear to be in most cases independent of the crater location or size. (Auth.)

  18. On Biometrics With Eye Movements.

    Science.gov (United States)

    Zhang, Youming; Juhola, Martti

    2017-09-01

    Eye movements are a relatively novel data source for biometric identification. When video cameras applied to eye tracking become smaller and more efficient, this data source could offer interesting opportunities for the development of eye movement biometrics. In this paper, we study primarily biometric identification as seen as a classification task of multiple classes, and secondarily biometric verification considered as binary classification. Our research is based on the saccadic eye movement signal measurements from 109 young subjects. In order to test the data measured, we use a procedure of biometric identification according to the one-versus-one (subject) principle. In a development from our previous research, which also involved biometric verification based on saccadic eye movements, we now apply another eye movement tracker device with a higher sampling frequency of 250 Hz. The results obtained are good, with correct identification rates at 80-90% at their best.

  19. Eye-based head gestures

    DEFF Research Database (Denmark)

    Mardanbegi, Diako; Witzner Hansen, Dan; Pederson, Thomas

    2012-01-01

    A novel method for video-based head gesture recognition using eye information by an eye tracker has been proposed. The method uses a combination of gaze and eye movement to infer head gestures. Compared to other gesture-based methods a major advantage of the method is that the user keeps the gaze...... mobile phone screens. The user study shows that the method detects a set of defined gestures reliably.......A novel method for video-based head gesture recognition using eye information by an eye tracker has been proposed. The method uses a combination of gaze and eye movement to infer head gestures. Compared to other gesture-based methods a major advantage of the method is that the user keeps the gaze...

  20. Eye laterality: a comprehensive analysis in refractive surgery candidates.

    Science.gov (United States)

    Linke, Stephan J; Druchkiv, Vasyl; Steinberg, Johannes; Richard, Gisbert; Katz, Toam

    2013-08-01

    To explore eye laterality (higher refractive error in one eye) and its association with refractive state, spherical/astigmatic anisometropia, age and sex in refractive surgery candidates. Medical records of 12 493 consecutive refractive surgery candidates were filtered. Refractive error (subjective and cycloplegic) was measured in each subject and correlated with eye laterality. Only subjects with corrected distance visual acuity (CDVA) of >20/22 in each eye were enrolled to exclude amblyopia. Associations between eye laterality and refractive state were analysed by means of t-test, chi-squared test, Spearman's correlation and multivariate logistic regression analysis, respectively. There was no statistically significant difference in spherical equivalent between right (-3.47 ± 2.76 D) and left eyes (-3.47 ± 2.76 D, p = 0.510; Pearson's r = 0.948, p laterality for anisometropia >2.5 D in myopic (-5.64 ± 2.5 D versus -4.92 ± 2.6 D; p = 0.001) and in hyperopic (4.44 ± 1.69 D versus 3.04 ± 1.79 D; p = 0.025) subjects, (II) a tendency for left eye cylindrical laterality in myopic subjects, and (III) myopic male subjects had a higher prevalence of left eye laterality. (IV) Age did not show any significant impact on laterality. Over the full refractive spectrum, this study confirmed previously described strong interocular refractive correlation but revealed a statistically significant higher rate of right eye laterality for anisometropia >2.5 D. In general, our results support the use of data from one eye only in studies of ocular refraction. © 2013 The Authors. Acta Ophthalmologica © 2013 Acta Ophthalmologica Scandinavica Foundation.

  1. Cluster PEACE observations of electrons of spacecraft origin

    Directory of Open Access Journals (Sweden)

    S. Szita

    2001-09-01

    Full Text Available The two PEACE (Plasma Electron And Current Experiment sensors on board each Cluster spacecraft sample the electron velocity distribution across the full 4 solid angle and the energy range 0.7 eV to 26 keV with a time resolution of 4 s. We present high energy and angular resolution 3D observations of electrons of spacecraft origin in the various environments encountered by the Cluster constellation, including a lunar eclipse interval where the spacecraft potential was reduced but remained positive, and periods of ASPOC (Active Spacecraft POtential Control operation which reduced the spacecraft potential. We demonstrate how the spacecraft potential may be found from a gradient change in the PEACE low energy spectrum, and show how the observed spacecraft electrons are confined by the spacecraft potential. We identify an intense component of the spacecraft electrons with energies equivalent to the spacecraft potential, the arrival direction of which is seen to change when ASPOC is switched on. Another spacecraft electron component, observed in the sunward direction, is reduced in the eclipse but unaffected by ASPOC, and we believe this component is produced in the analyser by solar UV. We find that PEACE anodes with a look direction along the spacecraft surfaces are more susceptible to spacecraft electron contamination than those which look perpendicular to the surface, which justifies the decision to mount PEACE with its field-of-view radially outward rather than tangentially.Key words. Magnetosheric physics (general or miscellaneous Space plasma physics (spacecraft sheaths, wakes, charging

  2. Electromagnetic Dissociation and Spacecraft Electronics Damage

    Science.gov (United States)

    Norbury, John W.

    2016-01-01

    When protons or heavy ions from galactic cosmic rays (GCR) or solar particle events (SPE) interact with target nuclei in spacecraft, there can be two different types of interactions. The more familiar strong nuclear interaction often dominates and is responsible for nuclear fragmentation in either the GCR or SPE projectile nucleus or the spacecraft target nucleus. (Of course, the proton does not break up, except possibly to produce pions or other hadrons.) The less familiar, second type of interaction is due to the very strong electromagnetic fields that exist when two charged nuclei pass very close to each other. This process is called electromagnetic dissociation (EMD) and primarily results in the emission of neutrons, protons and light ions (isotopes of hydrogen and helium). The cross section for particle production is approximately defined as the number of particles produced in nucleus-nucleus collisions or other types of reactions. (There are various kinematic and other factors which multiply the particle number to arrive at the cross section.) Strong, nuclear interactions usually dominate the nuclear reactions of most interest that occur between GCR and target nuclei. However, for heavy nuclei (near Fe and beyond) at high energy the EMD cross section can be much larger than the strong nuclear interaction cross section. This paper poses a question: Are there projectile or target nuclei combinations in the interaction of GCR or SPE where the EMD reaction cross section plays a dominant role? If the answer is affirmative, then EMD mechanisms should be an integral part of codes that are used to predict damage to spacecraft electronics. The question can become more fine-tuned and one can ask about total reaction cross sections as compared to double differential cross sections. These issues will be addressed in the present paper.

  3. Spacecraft computer technology at Southwest Research Institute

    Science.gov (United States)

    Shirley, D. J.

    1993-01-01

    Southwest Research Institute (SwRI) has developed and delivered spacecraft computers for a number of different near-Earth-orbit spacecraft including shuttle experiments and SDIO free-flyer experiments. We describe the evolution of the basic SwRI spacecraft computer design from those weighing in at 20 to 25 lb and using 20 to 30 W to newer models weighing less than 5 lb and using only about 5 W, yet delivering twice the processing throughput. Because of their reduced size, weight, and power, these newer designs are especially applicable to planetary instrument requirements. The basis of our design evolution has been the availability of more powerful processor chip sets and the development of higher density packaging technology, coupled with more aggressive design strategies in incorporating high-density FPGA technology and use of high-density memory chips. In addition to reductions in size, weight, and power, the newer designs also address the necessity of survival in the harsh radiation environment of space. Spurred by participation in such programs as MSTI, LACE, RME, Delta 181, Delta Star, and RADARSAT, our designs have evolved in response to program demands to be small, low-powered units, radiation tolerant enough to be suitable for both Earth-orbit microsats and for planetary instruments. Present designs already include MIL-STD-1750 and Multi-Chip Module (MCM) technology with near-term plans to include RISC processors and higher-density MCM's. Long term plans include development of whole-core processors on one or two MCM's.

  4. Ultraviolet radiation: the eye

    International Nuclear Information System (INIS)

    Cesarini, J.P.; Sliney, D.H.

    1996-01-01

    Under most conditions, the eye is well adapted to protect itself against ultraviolet radiation encountered in the outdoor environment as a result of the exposure geometry of the sun. Only when snow is on the ground does one experience acute effects of UV sunlight exposure (i.e. snow blindness, or photokeratitis). With regard to artificial sources, there are many occasions where one views bright light sources such as tungsten-halogen lamps, arc lamps and welding arcs. Such viewing is normally only momentary because of the aversion response to bright light and due to discomfort glare. However, such an aversion does not take place for germicidal lamps and other UV lamps which do not contain a strong visible component in their spectrum. The adverse effects from viewing such sources has been studied for decades and during the last two decades guidelines for limiting exposure to protect the eye have been developed. The guidelines were fostered to a large extent by the growing use of lasers and the quickly recognized hazard posed by viewing laser sources. (author)

  5. Chapter 2. Eyes

    International Nuclear Information System (INIS)

    Blanquet, P.

    1975-01-01

    Ocular scintigraphy can now be carried out with several tracers: 131 I diiodofluorescein and sup(99m)Tc, hypervascularisation indicators; 131 I iodinated chloroquine, melanoma selective. The detector used is an Anger scintillation camera coupled to a multiparameter analysis chain or a computer. The ''pin-hole'' type collimator, which has a stenopaeic opening in front of each eye, is adaptable to any inter-pupil distance. The very simple scintigraphic procedure is described. The results, taken from two statistical studies on 198 and 80 patients respectively, concern the main types of eye disease encountered: malignant melanic tumours, other tumours, metastases, choroiditis, idiopathic detachments of the retina etc... The interpretation of the scintigrams and the problems involved are considered. Finally the main indications of the method are defined with emphasis on the possibilities of double scintigraphy, diiodofluorescein only showing up the hypervascularisation often associated with the tumour whereas iodinated chloroquine, when the result is positive, points to the presence of a malignant melanoma [fr

  6. Post-LASIK dry eye

    Science.gov (United States)

    Shtein, Roni M

    2011-01-01

    Laser-assisted in situ keratomileusis (LASIK) is a frequently performed corneal refractive surgery with excellent refractive outcomes. The most common complication of LASIK is dry eyes, with virtually all patients developing some degree of dryness in the immediate postoperative period. Identifying preoperative dry eyes, and conscientious attention and treatment in the perioperative time period, can lead to enhanced patient satisfaction and more accurate visual outcomes. Improved understanding of the development of dry eyes after LASIK will advance our understanding of the complex pathophysiology of dry eye disease. PMID:22174730

  7. Juvenile eye growth, when completed?

    DEFF Research Database (Denmark)

    Fledelius, Hans C; Christensen, Anders S; Fledelius, Christian

    2014-01-01

    PURPOSE: To test Sorsby's classical statement of axial eye growth as completed at the age of 13 years, with a view also to differentiating between basic eye growth and juvenile elongation associated with eventual refractive change towards myopia. METHODS: (i) A total of 160 healthy eyes close...... about age 13 as general limit found support from the cross-sectional data, which suggested stable emmetropic eye size from about 11-12 years, with an average apparently outgrown male emmetropic value of 23.5 mm versus females' 22.9 mm. The longitudinal data, however, showed emmetropic growth also beyond...

  8. Soyuz Spacecraft Transported to Launch Pad

    Science.gov (United States)

    2003-01-01

    The Soyuz TMA-3 spacecraft and its booster rocket (rear view) is shown on a rail car for transport to the launch pad where it was raised to a vertical launch position at the Baikonur Cosmodrome, Kazakhstan on October 16, 2003. Liftoff occurred on October 18th, transporting a three man crew to the International Space Station (ISS). Aboard were Michael Foale, Expedition-8 Commander and NASA science officer; Alexander Kaleri, Soyuz Commander and flight engineer, both members of the Expedition-8 crew; and European Space agency (ESA) Astronaut Pedro Duque of Spain. Photo Credit: 'NASA/Bill Ingalls'

  9. Effects of Spacecraft Landings on the Moon

    Science.gov (United States)

    Metzger, Philip T.; Lane, John E.

    2013-01-01

    The rocket exhaust of spacecraft landing on the Moon causes a number of observable effects that need to be quantified, including: disturbance of the regolith and volatiles at the landing site; damage to surrounding hardware such as the historic Apollo sites through the impingement of high-velocity ejecta; and levitation of dust after engine cutoff through as-yet unconfirmed mechanisms. While often harmful, these effects also beneficially provide insight into lunar geology and physics. Some of the research results from the past 10 years is summarized and reviewed here.

  10. Fault Detection and Isolation for Spacecraft

    DEFF Research Database (Denmark)

    Jensen, Hans-Christian Becker; Wisniewski, Rafal

    2002-01-01

    This article realizes nonlinear Fault Detection and Isolation for actuators, given there is no measurement of the states in the actuators. The Fault Detection and Isolation of the actuators is instead based on angular velocity measurement of the spacecraft and knowledge about the dynamics...... of the satellite. The algorithms presented in this paper are based on a geometric approach to achieve nonlinear Fault Detection and Isolation. The proposed algorithms are tested in a simulation study and the pros and cons of the algorithms are discussed....

  11. Aircraft, ships, spacecraft, nuclear plants and quality

    International Nuclear Information System (INIS)

    Patrick, M.G.

    1984-05-01

    A few quality assurance programs outside the purview of the Nuclear Regulatory Commission were studied to identify features or practices which the NRC could use to enhance its program for assuring quality in the design and construction of nuclear power plants. The programs selected were: the manufacture of large commercial transport aircraft, regulated by the Federal Aviation Administration; US Navy shipbuilding; commercial shipbuilding regulated by the Maritime Administration and the US Coast Guard; Government-owned nuclear plants under the Department of Energy; spacecraft under the National Aeronautics and Space Administration; and the construction of nuclear power plants in Canada, West Germany, France, Japan, Sweden, and the United Kingdom

  12. SSS-A spacecraft and experiment description.

    Science.gov (United States)

    Longanecker, G. W.; Hoffman, R. A.

    1973-01-01

    The scientific objectives of the Explorer-45 mission are discussed. The primary objective is the study of the ring current responsible for the main phase of magnetic storms. Closely associated with this objective is the determination of the relationship between magnetic storms, substorms, and the acceleration of charged particles in the magnetosphere. Further objectives are the measurement of a wide range of proton, electron and alpha-particle energies, and studies of wave-particle interactions responsible for particle transport and loss in the inner magnetosphere. The orbital parameters, the spacecraft itself, and some of its unique features, such as the data handling system, which is programmable from the ground, are described.

  13. Utah Fly's Eye detector

    Energy Technology Data Exchange (ETDEWEB)

    Baltrusaitis, R.M.; Cady, R.; Cassiday, G.L.; Cooper, R.; Elbert, J.W.; Gerhardy, P.R.; Ko, S.; Loh, E.C.; Salamon, M.; Steck, D.; Sokolsky, P.

    1985-10-15

    We report the details of the design, operation and performance of the University of Utah Fly's Eye detector which was built to record the passage of ultra-high energy cosmic rays through the atmosphere via atmospheric fluorescence. Emphasized in the presentation are (1) light production by charged particles in the atmosphere, (2) kinematics of an EAS as seen by the Fly's Eye, (3) signal to noise considerations and its impact on detector design, (4) details of detector hardware and software, (5) detector calibration, (6) techniques employed in measurement of shower longitudinal development profiles and primary particle energy, and (7) assessment of detector performance by a comparison of Monte Carlo and real data distributions. (orig.).

  14. Association of IL-21 cytokine with severity of primary Sjögren syndrome dry eye.

    Science.gov (United States)

    Lim, Sung A; Nam, Doo Hyun; Lee, Jee Hye; Kwok, Seung-Ki; Park, Sung-Hwan; Chung, So-Hyang

    2015-03-01

    IL-21 plays an important role in primary Sjögren syndrome (SS) pathogenesis. The purpose of this study was to evaluate IL-21 expression in tears and the conjunctiva and to analyze the impact of IL-21 on primary SS dry eyes. Eighty subjects were enrolled in this study: 30 patients with primary SS dry eye (30 eyes); 30 patients with non-SS dry eye (30 eyes), and 20 normal controls. Tear IL-21 levels were measured by flow cytometry, and IL-21 gene expression in the conjunctiva from impression cytology was evaluated by quantitative polymerase chain reaction. Ocular Surface Disease Index, tear film breakup time, Schirmer I test, and ocular surface staining scores were obtained for all patients. Primary SS dry eyes had significantly higher tear IL-21 levels than non-SS dry eyes and normal controls (P dry eyes than in non-SS dry eyes and normal controls (P dry eyes and controls. The tear IL-21 level was significantly correlated with ocular surface stain scores (r = 0.54, P dry eyes. Our findings suggest that severity of primary SS dry eye is associated with IL-21.

  15. Eye Movement Abnormalities in Multiple Sclerosis: Pathogenesis, Modeling, and Treatment

    Directory of Open Access Journals (Sweden)

    Alessandro Serra

    2018-02-01

    Full Text Available Multiple sclerosis (MS commonly causes eye movement abnormalities that may have a significant impact on patients’ disability. Inflammatory demyelinating lesions, especially occurring in the posterior fossa, result in a wide range of disorders, spanning from acquired pendular nystagmus (APN to internuclear ophthalmoplegia (INO, among the most common. As the control of eye movements is well understood in terms of anatomical substrate and underlying physiological network, studying ocular motor abnormalities in MS provides a unique opportunity to gain insights into mechanisms of disease. Quantitative measurement and modeling of eye movement disorders, such as INO, may lead to a better understanding of common symptoms encountered in MS, such as Uhthoff’s phenomenon and fatigue. In turn, the pathophysiology of a range of eye movement abnormalities, such as APN, has been clarified based on correlation of experimental model with lesion localization by neuroimaging in MS. Eye movement disorders have the potential of being utilized as structural and functional biomarkers of early cognitive deficit, and possibly help in assessing disease status and progression, and to serve as platform and functional outcome to test novel therapeutic agents for MS. Knowledge of neuropharmacology applied to eye movement dysfunction has guided testing and use of a number of pharmacological agents to treat some eye movement disorders found in MS, such as APN and other forms of central nystagmus.

  16. Eye Movements in Darkness Modulate Self-Motion Perception.

    Science.gov (United States)

    Clemens, Ivar Adrianus H; Selen, Luc P J; Pomante, Antonella; MacNeilage, Paul R; Medendorp, W Pieter

    2017-01-01

    During self-motion, humans typically move the eyes to maintain fixation on the stationary environment around them. These eye movements could in principle be used to estimate self-motion, but their impact on perception is unknown. We had participants judge self-motion during different eye-movement conditions in the absence of full-field optic flow. In a two-alternative forced choice task, participants indicated whether the second of two successive passive lateral whole-body translations was longer or shorter than the first. This task was used in two experiments. In the first ( n = 8), eye movements were constrained differently in the two translation intervals by presenting either a world-fixed or body-fixed fixation point or no fixation point at all (allowing free gaze). Results show that perceived translations were shorter with a body-fixed than a world-fixed fixation point. A linear model indicated that eye-movement signals received a weight of ∼25% for the self-motion percept. This model was independently validated in the trials without a fixation point (free gaze). In the second experiment ( n = 10), gaze was free during both translation intervals. Results show that the translation with the larger eye-movement excursion was judged more often to be larger than chance, based on an oculomotor choice probability analysis. We conclude that eye-movement signals influence self-motion perception, even in the absence of visual stimulation.

  17. Small Rocket/Spacecraft Technology (SMART) Platform

    Science.gov (United States)

    Esper, Jaime; Flatley, Thomas P.; Bull, James B.; Buckley, Steven J.

    2011-01-01

    The NASA Goddard Space Flight Center (GSFC) and the Department of Defense Operationally Responsive Space (ORS) Office are exercising a multi-year collaborative agreement focused on a redefinition of the way space missions are designed and implemented. A much faster, leaner and effective approach to space flight requires the concerted effort of a multi-agency team tasked with developing the building blocks, both programmatically and technologically, to ultimately achieve flights within 7-days from mission call-up. For NASA, rapid mission implementations represent an opportunity to find creative ways for reducing mission life-cycle times with the resulting savings in cost. This in tum enables a class of missions catering to a broader audience of science participants, from universities to private and national laboratory researchers. To that end, the SMART (Small Rocket/Spacecraft Technology) micro-spacecraft prototype demonstrates an advanced avionics system with integrated GPS capability, high-speed plug-and-playable interfaces, legacy interfaces, inertial navigation, a modular reconfigurable structure, tunable thermal technology, and a number of instruments for environmental and optical sensing. Although SMART was first launched inside a sounding rocket, it is designed as a free-flyer.

  18. Time delay interferometry with moving spacecraft arrays

    International Nuclear Information System (INIS)

    Tinto, Massimo; Estabrook, F.B.; Armstrong, J.W.

    2004-01-01

    Space-borne interferometric gravitational wave detectors, sensitive in the low-frequency (millihertz) band, will fly in the next decade. In these detectors the spacecraft-to-spacecraft light-travel-times will necessarily be unequal, time varying, and (due to aberration) have different time delays on up and down links. The reduction of data from moving interferometric laser arrays in solar orbit will in fact encounter nonsymmetric up- and down-link light time differences that are about 100 times larger than has previously been recognized. The time-delay interferometry (TDI) technique uses knowledge of these delays to cancel the otherwise dominant laser phase noise and yields a variety of data combinations sensitive to gravitational waves. Under the assumption that the (different) up- and down-link time delays are constant, we derive the TDI expressions for those combinations that rely only on four interspacecraft phase measurements. We then turn to the general problem that encompasses time dependence of the light-travel times along the laser links. By introducing a set of noncommuting time-delay operators, we show that there exists a quite general procedure for deriving generalized TDI combinations that account for the effects of time dependence of the arms. By applying our approach we are able to re-derive the 'flex-free' expression for the unequal-arm Michelson combinations X 1 , and obtain the generalized expressions for the TDI combinations called relay, beacon, monitor, and symmetric Sagnac

  19. Relativistic effects of spacecraft with circumnavigating observer

    Science.gov (United States)

    Shanklin, Nathaniel; West, Joseph

    A variation of the recently introduced Trolley Paradox, itself is a variation of the Ehrenfest Paradox is presented. In the Trolley Paradox, a ``stationary'' set of observers tracking a wheel rolling with a constant velocity find that the wheel travels further than its rest length circumference during one revolution of the wheel, despite the fact that the Lorentz contracted circumference is less than its rest value. In the variation presented, a rectangular spacecraft with onboard observers moves with constant velocity and is circumnavigated by several small ``sloops'' forming teams of inertial observers. This whole precession moves relative to a set of ``stationary'' Earth observers. Two cases are presented, one in which the sloops are evenly spaced according to the spacecraft observers, and one in which the sloops are evenly spaced according to the Earth observes. These two cases, combined with the rectangular geometry and an emphasis on what is seen by, and what is measured by, each set of observers is very helpful in sorting out the apparent contradictions. To aid in the visualizations stationary representations in excel along with animation in Visual Python and Unity are presented. The analysis presented is suitable for undergraduate physics majors.

  20. Wavefront Derived Refraction and Full Eye Biometry in Pseudophakic Eyes.

    Directory of Open Access Journals (Sweden)

    Xinjie Mao

    Full Text Available To assess wavefront derived refraction and full eye biometry including ciliary muscle dimension and full eye axial geometry in pseudophakic eyes using spectral domain OCT equipped with a Shack-Hartmann wavefront sensor.Twenty-eight adult subjects (32 pseudophakic eyes having recently undergone cataract surgery were enrolled in this study. A custom system combining two optical coherence tomography systems with a Shack-Hartmann wavefront sensor was constructed to image and monitor changes in whole eye biometry, the ciliary muscle and ocular aberration in the pseudophakic eye. A Badal optical channel and a visual target aligning with the wavefront sensor were incorporated into the system for measuring the wavefront-derived refraction. The imaging acquisition was performed twice. The coefficients of repeatability (CoR and intraclass correlation coefficient (ICC were calculated.Images were acquired and processed successfully in all patients. No significant difference was detected between repeated measurements of ciliary muscle dimension, full-eye biometry or defocus aberration. The CoR of full-eye biometry ranged from 0.36% to 3.04% and the ICC ranged from 0.981 to 0.999. The CoR for ciliary muscle dimensions ranged from 12.2% to 41.6% and the ICC ranged from 0.767 to 0.919. The defocus aberrations of the two measurements were 0.443 ± 0.534 D and 0.447 ± 0.586 D and the ICC was 0.951.The combined system is capable of measuring full eye biometry and refraction with good repeatability. The system is suitable for future investigation of pseudoaccommodation in the pseudophakic eye.

  1. Spacecraft Dynamic Characterization by Strain Energies Method

    Science.gov (United States)

    Bretagne, J.-M.; Fragnito, M.; Massier, S.

    2002-01-01

    In the last years the significant increase in satellite broadcasting demand, with the wide band communication dawn, has given a great impulse to the telecommunication satellite market. The big demand is translated from operators (such as SES/Astra, Eutelsat, Intelsat, Inmarsat, EuroSkyWay etc.) in an increase of orders of telecom satellite to the world industrials. The largest part of these telecom satellite orders consists of Geostationary platforms which grow more and more in mass (over 5 tons) due to an ever longer demanded lifetime (up to 20 years), and become more complex due to the need of implementing an ever larger number of repeaters, antenna reflectors and feeds, etc... In this frame, the mechanical design and verification of these large spacecraft become difficult and ambitious at the same time, driven by the dry mass limitation objective. By the Finite Element Method (FEM), and on the basis of the telecom satellite heritage of a world leader constructor such as Alcatel Space Industries it is nowadays possible to model these spacecraft in a realistic and confident way in order to identify the main global dynamic aspects such as mode shapes, mass participation and/or dynamic responses. But on the other hand, one of the main aims consists in identifying soon in a program the most critical aspects of the system behavior in the launch dynamic environment, such as possible dynamic coupling between the different subsystems and secondary structures of the spacecraft (large deployable reflectors, thrusters, etc.). To this aim a numerical method has been developed in the frame of the Alcatel SPACEBUS family program, using MSC/Nastran capabilities and it is presented in this paper. The method is based on Spacecraft sub-structuring and strain energy calculation. The method mainly consists of two steps : 1) subsystem modal strain energy ratio (with respect to the global strain energy); 2) subsystem strain energy calculation for each mode according to the base driven

  2. Contact Lens-Related Eye Infections

    Science.gov (United States)

    ... Español Eye Health / Eye Health A-Z Contact Lens-Related Eye Infections Sections Contact Lens-Related Eye ... Six Steps to Avoid Contact Lens Infections Contact Lens-Related Eye Infections Leer en Español: Infecciones relacionadas ...

  3. The impact of glaucoma referral refinement criteria on referral to, and first-visit discharge rates from, the hospital eye service: the Health Innovation & Education Cluster (HIEC) Glaucoma Pathways project.

    Science.gov (United States)

    Ratnarajan, Gokulan; Newsom, Wendy; French, Karen; Kean, Jane; Chang, Lydia; Parker, Mike; Garway-Heath, David F; Bourne, Rupert R A

    2013-03-01

    To assess the impact of referral refinement criteria on the number of patients referred to, and first-visit discharges from, the Hospital Eye Service (HES) in relation to the National Institute for Health & Clinical Excellence (NICE) Glaucoma Guidelines, Joint College Group Guidance (JCG) and the NICE commissioning guidance. All low-risk (one risk factor: suspicious optic disc, abnormal visual field (VF), raised intra-ocular pressure (IOP) (22-28 mmHg) or IOP asymmetry (>5 mmHg) and high-risk (more than one risk factor, shallow anterior chamber or IOP >28 mmHg) referrals to the HES from 2006 to 2011 were analysed. Low-risk referrals were seen by Optometrists with a specialist interest in glaucoma and high-risk referrals were referred directly to the HES. Two thousand nine hundred and twelve patient records were analysed. The highest Consultant first-visit discharge rates were for referrals based on IOP alone (45% for IOP 22-28 mmHg) and IOP asymmetry (53%), VF defect alone (46%) and for abnormal IOP and VF (54%). The lowest first-visit discharge rates were for referrals for suspicious optic disc (19%) and IOP >28 mmHg (22%). 73% of patients aged 65-80 and 60% of patients aged >80 who were referred by the OSI due to an IOP between 22-28 mmHg would have satisfied the JCG criteria for non-referral. For patients referred with an IOP >28 mmHg and an otherwise normal examination, adherence to the NICE commissioning guidance would have resulted in 6% fewer referrals. In 2010 this scheme reduced the number of patients attending the HES by 15%, which resulted in a saving of £16 258 (13%). The results support that referrals for a raised IOP alone or in combination with an abnormal VF be classified as low-risk and undergo referral refinement. Adherence to the JCG and the NICE commissioning guidance as onward referral criteria for specialist optometrists in this referral refinement scheme would result in fewer referrals. Ophthalmic & Physiological Optics © 2013 The College

  4. Eye tracking for visual marketing

    NARCIS (Netherlands)

    Wedel, M.; Pieters, R.

    2008-01-01

    We provide the theory of visual attention and eye-movements that serves as a basis for evaluating eye-tracking research and for discussing salient and emerging issues in visual marketing. Motivated from its rising importance in marketing practice and its potential for theoretical contribution, we

  5. Eye Movements in Gaze Interaction

    DEFF Research Database (Denmark)

    Møllenbach, Emilie; Hansen, John Paulin; Lillholm, Martin

    2013-01-01

    Gaze as a sole input modality must support complex navigation and selection tasks. Gaze interaction combines specific eye movements and graphic display objects (GDOs). This paper suggests a unifying taxonomy of gaze interaction principles. The taxonomy deals with three types of eye movements...

  6. Compensatory eye movements in mice

    NARCIS (Netherlands)

    A.M. van Alphen (Arjan)

    2002-01-01

    textabstractThis thesis will address the generation of compensatory eye movements in naturally mutated or genetically modified mice. The reason for generating compensatory eye movements is solely related to the requirements for good vision. In a subject moving through its environment the projection

  7. Telemedicine and Diabetic Eye Disease

    Centers for Disease Control (CDC) Podcasts

    We know that the leading cause of blindness in working-age adults is eye disease related to poorly managed diabetes. In a prevention research study, telemedicine was shown to increase the number of people getting screened for diabetic eye disease.

  8. Genetic Testing and Eye Disease

    Science.gov (United States)

    ... condition called Cogan’s syndrome. Google AI May Reveal Health Risks Through Your Eyes FEB 20, 2018 By Ari Soglin Researchers at Google say a new application of artificial intelligence shows whether a patient’s eyes point to high ...

  9. Penetrating eye injury in war.

    Science.gov (United States)

    Biehl, J W; Valdez, J; Hemady, R K; Steidl, S M; Bourke, D L

    1999-11-01

    The percentage of penetrating eye injuries in war has increased significantly in this century compared with the total number of combat injuries. With the increasing use of fragmentation weapons and possibly laser weapons on the battle-field in the future, the rate of eye injuries may exceed the 13% of the total military injuries found in Operations Desert Storm/Shield. During the Iran-Iraq War (1980-1988), eye injuries revealed that retained foreign bodies and posterior segment injuries have an improved prognosis in future military ophthalmic surgery as a result of modern diagnostic and treatment modalities. Compared with the increasing penetrating eye injuries on the battlefield, advances in ophthalmic surgery are insignificant. Eye armor, such as visors that flip up and down and protect the eyes from laser injury, needs to be developed. Similar eye protection is being developed in civilian sportswear. Penetrating eye injury in the civilian sector is becoming much closer to the military model and is now comparable for several reasons.

  10. Apoptosis of conjunctival epithelial cells before and after the application of autologous serum eye drops in severe dry eye disease.

    Science.gov (United States)

    Rybickova, Ivana; Vesela, Viera; Fales, Ivan; Skalicka, Pavlina; Jirsova, Katerina

    2016-06-01

    To assess the impact of autologous serum eye drops on the level of ocular surface apoptosis in patients with bilateral severe dry eye disease. This prospective study was conducted on 10 patients with severe dry eye due to graft versus host disease (group 1) and 6 patients with severe dry eye due to primary Sjögren's syndrome (group 2). Impression cytology specimens from the bulbar conjunctiva were obtained before and after a three-month treatment with 20% autologous serum eye drops applied a maximum of 12 times a day together with regular therapy with artificial tears. The percentage of apoptotic epithelial cells was evaluated immunochemically using anti-active caspase 3 antibody. In group 1, the mean percentage of apoptotic cells was 3.6% before the treatment. The three-month treatment led to a significant decrease to a mean percentage of 1.8% (P = 0.028). The mean percentage of apoptotic conjunctival cells decreased from 5.4% before the treatment to 3.8% in group 2; however, these results did not reach the level of significance. Three-month autologous serum treatment led to the improvement of ocular surface apoptosis, especially in the group of patients with severe dry eye due to graft versus host disease. This result supports the very positive effect of autologous serum on the ocular surface in patients suffering from severe dry eye.

  11. Dry eyes: etiology and management.

    Science.gov (United States)

    Latkany, Robert

    2008-07-01

    Until recently, the cause of dry eye syndrome was uncertain and the treatment was palliative. Since discovering that dry eyes are caused by inflammation, there has been an abundance of research focusing on anti-inflammatory therapies, other contributing causes, and better diagnostic testing. This review summarizes some of the interesting published research on ocular surface disease over the past year. The definition of dry eye now highlights the omnipresent symptom of blurry vision. The re-evaluation of ocular surface staining, tear meniscus height, and visual change will allow for a better diagnosis and understanding of dry eyes. Punctal plugs, and oral and topical anti-inflammatory use will strengthen our arsenal against ocular surface disease. Major progress has occurred in the past few years in gaining a better understanding of the etiology of dry eye syndrome, which will inevitably lead to more effective therapeutic options.

  12. Spacecraft Dynamics Should be Considered in Kalman Filter Attitude Estimation

    Science.gov (United States)

    Yang, Yaguang; Zhou, Zhiqiang

    2016-01-01

    Kalman filter based spacecraft attitude estimation has been used in some high-profile missions and has been widely discussed in literature. While some models in spacecraft attitude estimation include spacecraft dynamics, most do not. To our best knowledge, there is no comparison on which model is a better choice. In this paper, we discuss the reasons why spacecraft dynamics should be considered in the Kalman filter based spacecraft attitude estimation problem. We also propose a reduced quaternion spacecraft dynamics model which admits additive noise. Geometry of the reduced quaternion model and the additive noise are discussed. This treatment is more elegant in mathematics and easier in computation. We use some simulation example to verify our claims.

  13. Electromagnetic Forces on a Relativistic Spacecraft in the Interstellar Medium

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, Thiem [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of); Loeb, Abraham, E-mail: thiemhoang@kasi.re.kr, E-mail: aloeb@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA (United States)

    2017-10-10

    A relativistic spacecraft of the type envisioned by the Breakthrough Starshot initiative will inevitably become charged through collisions with interstellar particles and UV photons. Interstellar magnetic fields would therefore deflect the trajectory of the spacecraft. We calculate the expected deflection for typical interstellar conditions. We also find that the charge distribution of the spacecraft is asymmetric, producing an electric dipole moment. The interaction between the moving electric dipole and the interstellar magnetic field is found to produce a large torque, which can result in fast oscillation of the spacecraft around the axis perpendicular to the direction of motion, with a period of ∼0.5 hr. We then study the spacecraft rotation arising from impulsive torques by dust bombardment. Finally, we discuss the effect of the spacecraft rotation and suggest several methods to mitigate it.

  14. The eye amputated - consequences of eye amputation with emphasis on clinical aspects, phantom eye syndrome and quality of life.

    Science.gov (United States)

    Rasmussen, Marie Louise Roed

    2010-12-01

    continuous sharp light or as moving dots. The most frequent triggers were darkness, closing of the eyes, fatigue and psychological stress. Fifty-four percent of the patients had visual hallucinations more than once a week. Ten patients were so visually disturbed that it interfered with their daily life. Approximately 23% of all EA experience phantom pain for several years after the surgery. Phantom pain was reported to be of three different qualities: (i) cutting, penetrating, gnawing or oppressive (n=19); (ii) radiating, zapping or shooting (n=8); (iii) superficial burning or stinging (n=5); or a mixture of these different pain qualities (n=7). The median intensity on a visual analogue scale, ranging from 0 to 100, was 36 [range: 1-89]. One-third of the patients experienced phantom pain every day. Chilliness, windy weather and psychological stress/fatigue were the most commonly reported triggers for pain. Factors associated with phantom pain were: ophthalmic pain before EA, the presence of implant and a patient reported high degree of conjunctival secretion. A common reason for EA is the presence of a painful blind eye. However, one third of these patients continue to have pain after the EA. Phantom sensations were present in 2% of the patients. The impact of an eye amputation is considerable. EA patients have poorer health related quality of life, poorer self-rated health and more perceived stress than does the general population. The largest differences in health related quality of life between the EA patients and the general population were related to role limitations due to emotional problems and mental health. Patients with the indication painful blind eye are having lower scores in all aspects of health related quality of life and perceived stress than patients with the indication neoplasm and trauma. The percentage of eye amputated which is divorced or separated was twice as high as in the general population. Furthermore, 25% retired or changed to part-time jobs due

  15. Keep an Eye on Your Eyes (A Cup of Health with CDC)

    Centers for Disease Control (CDC) Podcasts

    2013-05-09

    If you struggle to read the pages of a book or a billboard on the side of the road, you might be among the millions of Americans who suffer from vision impairment. Problems seeing can impact many daily activities. In this podcast, Dr. Jinan Saaddine discusses the importance of regular eye exams.  Created: 5/9/2013 by MMWR.   Date Released: 5/9/2013.

  16. 3D Display of Spacecraft Dynamics Using Real Telemetry

    Directory of Open Access Journals (Sweden)

    Sanguk Lee

    2002-12-01

    Full Text Available 3D display of spacecraft motion by using telemetry data received from satellite in real-time is described. Telemetry data are converted to the appropriate form for 3-D display by the real-time preprocessor. Stored playback telemetry data also can be processed for the display. 3D display of spacecraft motion by using real telemetry data provides intuitive comprehension of spacecraft dynamics.

  17. Structural Dynamic Analyses And Test Predictions For Spacecraft Structures With Non-Linearities

    Science.gov (United States)

    Vergniaud, Jean-Baptiste; Soula, Laurent; Newerla, Alfred

    2012-07-01

    The overall objective of the mechanical development and verification process is to ensure that the spacecraft structure is able to sustain the mechanical environments encountered during launch. In general the spacecraft structures are a-priori assumed to behave linear, i.e. the responses to a static load or dynamic excitation, respectively, will increase or decrease proportionally to the amplitude of the load or excitation induced. However, past experiences have shown that various non-linearities might exist in spacecraft structures and the consequences of their dynamic effects can significantly affect the development and verification process. Current processes are mainly adapted to linear spacecraft structure behaviour. No clear rules exist for dealing with major structure non-linearities. They are handled outside the process by individual analysis and margin policy, and analyses after tests to justify the CLA coverage. Non-linearities can primarily affect the current spacecraft development and verification process on two aspects. Prediction of flights loads by launcher/satellite coupled loads analyses (CLA): only linear satellite models are delivered for performing CLA and no well-established rules exist how to properly linearize a model when non- linearities are present. The potential impact of the linearization on the results of the CLA has not yet been properly analyzed. There are thus difficulties to assess that CLA results will cover actual flight levels. Management of satellite verification tests: the CLA results generated with a linear satellite FEM are assumed flight representative. If the internal non- linearities are present in the tested satellite then there might be difficulties to determine which input level must be passed to cover satellite internal loads. The non-linear behaviour can also disturb the shaker control, putting the satellite at risk by potentially imposing too high levels. This paper presents the results of a test campaign performed in

  18. Eye lens dose estimation during interventional radiology and its impact on the existing radiation protection and safety program: in the context with new International Commission on Radiological Protection guidelines

    International Nuclear Information System (INIS)

    Chaudhari, Suresh

    2014-01-01

    Interventional radiology procedures are used for diagnosing certain medical conditions. The radiologists and medical professionals are exposed to ionizing radiation from X-rays of the equipments and also from scattered radiation during these procedures. The radiation exposure to the eye is more important to be assessed while performing such procedures. ICRP has revised the annual dose limit to the lens of the eye from 150 mSv to 20 mSv. In view of this revision, a study was carried out to evaluate the dose to the lens of the eye during interventional radiology. The paper gives the details of calibration of TLDs using a head phantom, predict annual equivalent dose and also highlight the dependence of dose on the position of TLD on the head. It is observed the predicted annual equivalent doses to the lens of eye are in the range of 25 mGy to 37 mGy. The selection of dosimeter placement may also result in an uncertainty of -14% to 20%. (author)

  19. Sun, UV Radiation and Your Eyes

    Science.gov (United States)

    ... Sunglasses Sun Smart UV Safety Infographic The Sun, UV Radiation and Your Eyes Leer en Español: El ... Aug. 28, 2014 Keep an Eye on Ultraviolet (UV) Safety Eye medical doctors (ophthalmologists) caution us that ...

  20. Application of advanced electronics to a future spacecraft computer design

    Science.gov (United States)

    Carney, P. C.

    1980-01-01

    Advancements in hardware and software technology are summarized with specific emphasis on spacecraft computer capabilities. Available state of the art technology is reviewed and candidate architectures are defined.