Advanced EVA system design requirements study, executive summary

NASA Technical Reports Server (NTRS)

1986-01-01

Design requirements and criteria for the space station advanced Extravehicular Activity System (EVAS) including crew enclosures, portable life support systems, maneuvering propulsion systems, and related EVA support equipment were established. The EVA mission requirements, environments, and medical and physiological requirements, as well as operational, procedures and training issues were considered.

Study to evaluate the effect of EVA on payload systems. Volume 1: Executive summary. [project planning of space missions employing extravehicular activity as a means of cost reduction

NASA Technical Reports Server (NTRS)

Patrick, J. W.; Kraly, E. F.

1975-01-01

Programmatic benefits to payloads are examined which can result from the routine use of extravehicular activity (EVA) during space missions. Design and operations costs were compared for 13 representative baseline payloads to the costs of those payloads adapted for EVA operations. The EVA-oriented concepts developed in the study were derived from these baseline concepts and maintained mission and program objectives as well as basic configurations. This permitted isolation of cost saving factors associated specifically with incorporation of EVA in a variety of payload designs and operations. The study results were extrapolated to a total of 74 payload programs. Using appropriate complexity and learning factors, net EVA savings were extrapolated to over $551M for NASA and U.S. civil payloads for routine operations. Adding DOD and ESRO payloads increases the net estimated savings of $776M. Planned maintenance by EVA indicated an estimated $168M savings due to elimination of automated service equipment. Contingency problems of payloads were also analyzed to establish expected failure rates for shuttle payloads. The failure information resulted in an estimated potential for EVA savings of $1.9 B.

An Integrated Extravehicular Activity Research Plan

NASA Technical Reports Server (NTRS)

Abercromby, Andrew F. J.; Ross, Amy J.; Cupples, J. Scott

2016-01-01

Multiple organizations within NASA and outside of NASA fund and participate in research related to extravehicular activity (EVA). In October 2015, representatives of the EVA Office, the Crew and Thermal Systems Division (CTSD), and the Human Research Program (HRP) at NASA Johnson Space Center agreed on a formal framework to improve multi-year coordination and collaboration in EVA research. At the core of the framework is an Integrated EVA Research Plan and a process by which it will be annually reviewed and updated. The over-arching objective of the collaborative framework is to conduct multi-disciplinary cost-effective research that will enable humans to perform EVAs safely, effectively, comfortably, and efficiently, as needed to enable and enhance human space exploration missions. Research activities must be defined, prioritized, planned and executed to comprehensively address the right questions, avoid duplication, leverage other complementary activities where possible, and ultimately provide actionable evidence-based results in time to inform subsequent tests, developments and/or research activities. Representation of all appropriate stakeholders in the definition, prioritization, planning and execution of research activities is essential to accomplishing the over-arching objective. A formal review of the Integrated EVA Research Plan will be conducted annually. External peer review of all HRP EVA research activities including compilation and review of published literature in the EVA Evidence Book is already performed annually. Coordination with stakeholders outside of the EVA Office, CTSD, and HRP is already in effect on a study-by-study basis; closer coordination on multi-year planning with other EVA stakeholders including academia is being actively pursued. Details of the current Integrated EVA Research Plan are presented including description of ongoing and planned research activities in the areas of: Benchmarking; Anthropometry and Suit Fit; Sensors; Human-Suit Modeling; Suit Trauma Monitoring and Countermeasures; EVA Workload and Duration Effects; Decompression Sickness Risk Mitigation; Deconditioned EVA Performance; and Exploration EVA Concept of Operations.

Integrated Extravehicular Activity Human Research Plan: 2017

NASA Technical Reports Server (NTRS)

Abercromby, Andrew

2017-01-01

Multiple organizations within NASA as well as industry and academia fund and participate in research related to extravehicular activity (EVA). In October 2015, representatives of the EVA Office, the Crew and Thermal Systems Division (CTSD), and the Human Research Program (HRP) at NASA Johnson Space Center agreed on a formal framework to improve multi-year coordination and collaboration in EVA research. At the core of the framework is an Integrated EVA Human Research Plan and a process by which it will be annually reviewed and updated. The over-arching objective of the collaborative framework is to conduct multi-disciplinary cost-effective research that will enable humans to perform EVAs safely, effectively, comfortably, and efficiently, as needed to enable and enhance human space exploration missions. Research activities must be defined, prioritized, planned and executed to comprehensively address the right questions, avoid duplication, leverage other complementary activities where possible, and ultimately provide actionable evidence-based results in time to inform subsequent tests, developments and/or research activities. Representation of all appropriate stakeholders in the definition, prioritization, planning and execution of research activities is essential to accomplishing the over-arching objective. A formal review of the Integrated EVA Human Research Plan will be conducted annually. Coordination with stakeholders outside of the EVA Office, CTSD, and HRP is already in effect on a study-by-study basis; closer coordination on multi-year planning with other EVA stakeholders including academia is being actively pursued. Details of the preliminary Integrated EVA Human Research Plan are presented including description of ongoing and planned research activities in the areas of: physiological and performance capabilities; suit design parameters; EVA human health and performance modeling; EVA tasks and concepts of operations; EVA informatics; human-suit sensors; suit sizing and fit; and EVA injury risk and mitigation. This paper represents the 2017 update to the Integrated EVA Human Research Plan.

Advanced EVA Capabilities: A Study for NASA's Revolutionary Aerospace Systems Concept Program

NASA Technical Reports Server (NTRS)

Hoffman, Stephen J.

2004-01-01

This report documents the results of a study carried out as part of NASA s Revolutionary Aerospace Systems Concepts Program examining the future technology needs of extravehicular activities (EVAs). The intent of this study is to produce a comprehensive report that identifies various design concepts for human-related advanced EVA systems necessary to achieve the goals of supporting future space exploration and development customers in free space and on planetary surfaces for space missions in the post-2020 timeframe. The design concepts studied and evaluated are not limited to anthropomorphic space suits, but include a wide range of human-enhancing EVA technologies as well as consideration of coordination and integration with advanced robotics. The goal of the study effort is to establish a baseline technology "road map" that identifies and describes an investment and technical development strategy, including recommendations that will lead to future enhanced synergistic human/robot EVA operations. The eventual use of this study effort is to focus evolving performance capabilities of various EVA system elements toward the goal of providing high performance human operational capabilities for a multitude of future space applications and destinations. The data collected for this study indicate a rich and diverse history of systems that have been developed to perform a variety of EVA tasks, indicating what is possible. However, the data gathered for this study also indicate a paucity of new concepts and technologies for advanced EVA missions - at least any that researchers are willing to discuss in this type of forum.

A human factors analysis of EVA time requirements

NASA Technical Reports Server (NTRS)

Pate, D. W.

1996-01-01

Human Factors Engineering (HFE), also known as Ergonomics, is a discipline whose goal is to engineer a safer, more efficient interface between humans and machines. HFE makes use of a wide range of tools and techniques to fulfill this goal. One of these tools is known as motion and time study, a technique used to develop time standards for given tasks. A human factors motion and time study was initiated with the goal of developing a database of EVA task times and a method of utilizing the database to predict how long an ExtraVehicular Activity (EVA) should take. Initial development relied on the EVA activities performed during the STS-61 mission (Hubble repair). The first step of the analysis was to become familiar with EVAs and with the previous studies and documents produced on EVAs. After reviewing these documents, an initial set of task primitives and task time modifiers was developed. Videotaped footage of STS-61 EVAs were analyzed using these primitives and task time modifiers. Data for two entire EVA missions and portions of several others, each with two EVA astronauts, was collected for analysis. Feedback from the analysis of the data will be used to further refine the primitives and task time modifiers used. Analysis of variance techniques for categorical data will be used to determine which factors may, individually or by interactions, effect the primitive times and how much of an effect they have.

Advanced EVA system design requirements study

NASA Technical Reports Server (NTRS)

1986-01-01

Design requirements and criteria for the Space Station Advanced Extravehicular Activity System (EVAS) including crew enclosures, portable life support systems, maneuvering propulsion systems, and related extravehicular activity (EVA) support equipment were defined and established. The EVA mission requirements, environments, and medical and physiological requirements, as well as opertional, procedures, and training issues were considered.

EVA1A inhibits GBM cell proliferation by inducing autophagy and apoptosis.

PubMed

Shen, Xue; Kan, Shifeng; Liu, Zhen; Lu, Guang; Zhang, Xiaoyan; Chen, Yingyu; Bai, Yun

2017-03-01

Eva-1 homolog A (EVA1A) is a novel lysosome and endoplasmic reticulum-associated protein involved in autophagy and apoptosis. In this study, we constructed a recombinant adenovirus 5-EVA1A vector (Ad5-EVA1A) to overexpress EVA1A in glioblastoma (GBM) cell lines and evaluated its anti-tumor activities in vitro and in vivo. We found that overexpression of EVA1A in three GBM cell lines (U251, U87 and SHG44) resulted in a suppression of tumor cell growth via activation of autophagy and induction of cell apoptosis in a dose- and time-dependent manner. EVA1A-mediated autophagy was associated with inactivation of the mTOR/RPS6KB1 signaling pathway. Furthermore in vivo, overexpression of EVA1A successfully inhibited tumor growth in NOD/SCID mice. Our data suggest that EVA1A-induced autophagy and apoptosis play a role in suppressing the development of GBM and their up-regulation may be an effective method for treating this form of cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

Extravehicular activity at geosynchronous earth orbit

NASA Technical Reports Server (NTRS)

Shields, Nicholas, Jr.; Schulze, Arthur E.; Carr, Gerald P.; Pogue, William

1988-01-01

The basic contract to define the system requirements to support the Advanced Extravehicular Activity (EVA) has three phases: EVA in geosynchronous Earth orbit; EVA in lunar base operations; and EVA in manned Mars surface exploration. The three key areas to be addressed in each phase are: environmental/biomedical requirements; crew and mission requirements; and hardware requirements. The structure of the technical tasks closely follows the structure of the Advanced EVA studies for the Space Station completed in 1986.

Effect of PEG6000 on the in vitro and in vivo transdermal permeation of ondansetron hydrochloride from EVA1802 membranes.

PubMed

Krishnaiah, Yellela S R; Rama, Bukka; Raghumurthy, Vanambattina; Ramanamurthy, Kolapalli V; Satyanarayana, Vemulapalli

2009-01-01

The objective was to evaluate ethylene vinyl acetate (EVA) copolymer membranes with vinyl acetate content of 18% w/w (EVA1802) for transdermal delivery of ondansetron hydrochloride. The EVA1802 membranes containing selected concentrations (0, 5, 10 and 15% w/w) of PEG6000 were prepared, and subjected to in vitro permeation studies from a nerodilol-based drug reservoir. Flux of ondansetron from EVA1802 membranes without PEG6000 was 64.1 +/- 0.6 microg/cm(2.)h, and with 10%w/w of PEG6000 (EVA1802-PEG6000-10) it increased to 194.9 +/- 4.6 microg/cm(2.)h. However, with 15%w/w of PEG6000, EVA1802 membranes produced a burst release of drug which in turn decreased drug flux. The EVA1802-PEG6000-10 membrane was coated with an adhesive emulsion, applied to rat epidermis and subjected to in vitro permeation studies against controls. Flux of ondansetron from transdermal patch across rat epidermis was 111.7 +/- 1.3 microg/cm(2.)h, which is about 1.3 times the required flux. A TTS was fabricated using adhesive-coated EVA1802-PEG6000-10 membrane and other TTS components, and subjected to in vivo delivery in human volunteers against a control. It was concluded from the comparative pharmacokinetic study that TTS of ondansetron, prepared with EVA1802-PEG6000-10 membrane, provided average steady-state plasma concentration on par with multiple-dosed oral tablets, but with a low percent of peak-to-trough fluctuation.

Apollo 16 time and motion study

NASA Technical Reports Server (NTRS)

Kubis, J. F.; Elrod, J. T.; Rusnak, R.; Barnes, J. E.; Saxon, S. C.

1972-01-01

A time and motion study is presented of astronaut lunar surface activity on Apollo 16 which consists of five distinct analyses: an evaluation of lunar mobility, a comparison of task performance in 1-g training and lunar EVA, a study of metabolic costs and adaptation, a discussion of falls, and retrieval of fallen objects. Two basic mobility patterns, the hop or canter and the traditional walking gait, were consistently utilized in longer traverses. The metabolic rates associated with these two mobility types, each used by a different astronaut, were relatively equivalent. The time to perform tasks on the lunar surface was significantly longer (on the order of 70%) than the time to perform the same tasks during the last 1-g training session. These results corroborated the findings on Apollo 15 and were not significantly different from them. There was general improvement in lunar EVA performance upon repetition of tasks. Metabolic rate (BTU/hr.) and metabolic cost (BTU) decreased over successive EVAs. Specifically, the metabolic rate associated with riding the lunar roving vehicle (LRV) decreased by approximately 18% from EVA 1 to EVA 2 and by 15% from EVA 2 to EVA 3.

Do Astronauts have a Higher Rate of Orthopedic Shoulder Conditions than a Cohort of Working Professionals?

NASA Technical Reports Server (NTRS)

Laughlin, Mitzi S.; Murray, Jocelyn D.; Young, Millenia; Wear, Mary L.; Tarver, W. J.; Van Baalen, Mary

2016-01-01

Occupational surveillance of astronaut shoulder injuries began with operational concerns at the Neutral Buoyancy Laboratory (NBL) during Extra Vehicular Activity (EVA) training. NASA has implemented several occupational health initiatives during the past 20 years to decrease the number and severity of injuries, but the individual success rate is unknown. Orthopedic shoulder injury and surgery rates were calculated, but classifying the rates as normal, high or low was highly dependent on the comparison group. The purpose of this study was to identify a population of working professionals and compare orthopedic shoulder consultation and surgery rates.

Control of biofilm formation by poly-ethylene-co-vinyl acetate films incorporating nisin.

PubMed

Nostro, Antonia; Scaffaro, Roberto; Ginestra, Giovanna; D'Arrigo, Manuela; Botta, Luigi; Marino, Andreana; Bisignano, Giuseppe

2010-06-01

The aim of this study was to evaluate the effect of poly-ethylene-co-vinyl acetate (EVA) films incorporating different concentrations (0.1%, 0.5% and 1%) of nisin on the biofilm-forming ability of Listeria monocytogenes ATCC 7644, Staphylococcus aureus 815 and Staphylococcus epidermidis ATCC 35984. Nisin was incorporated into two grades of EVA (EVA14 and EVA28) in the melt during a common film-blowing operation. The efficacy of EVA/nisin films was evaluated by biofilm biomass measurements and Live/Dead staining in combination with fluorescence microscopy. In order to evaluate whether the nisin incorporation could modify the film surface properties, contact angle measurements and scanning electron microscopy were performed. The results revealed the efficacy of EVA14/nisin films in reducing biofilm formation on their surfaces with more evident effect for S. epidermidis than L. monocytogenes and S. aureus strains. In contrast, EVA28/nisin films showed unsatisfactory activity. Fluorescence microscopy confirmed poor biofilm formation on EVA14/nisin films, also characterised by the presence of dead cells. The data presented in this study offer new potential applications for developing strategies aimed to improve the effect of antimicrobial agents.

Evaluation of Visual Acuity Measurements after Autorefraction versus Manual Refraction in Eyes with and without Diabetic Macular Edema

PubMed Central

Sun, Jennifer K.; Qin, Haijing; Aiello, Lloyd Paul; Melia, Michele; Beck, Roy W.; Andreoli, Christopher M.; Edwards, Paul A.; Glassman, Adam R.; Pavlica, Michael R.

2012-01-01

Objective To compare visual acuity (VA) scores after autorefraction versus research protocol manual refraction in eyes of patients with diabetes and a wide range of VA. Methods Electronic Early Treatment Diabetic Retinopathy Study (E-ETDRS) VA Test© letter score (EVA) was measured after autorefraction (AR-EVA) and after Diabetic Retinopathy Clinical Research Network (DRCR.net) protocol manual refraction (MR-EVA). Testing order was randomized, study participants and VA examiners were masked to refraction source, and a second EVA utilizing an identical manual refraction (MR-EVAsupl) was performed to determine test-retest variability. Results In 878 eyes of 456 study participants, median MR-EVA was 74 (Snellen equivalent approximately 20/32). Spherical equivalent was often similar for manual and autorefraction (median difference: 0.00, 5th and 95th percentiles −1.75 to +1.13 Diopters). However, on average, MR-EVA results were slightly better than AR-EVA results across the entire VA range. Furthermore, variability between AR-EVA and MR-EVA was substantially greater than the test-retest variability of MR-EVA (P<0.001). Variability of differences was highly dependent on autorefractor model. Conclusions Across a wide range of VA at multiple sites using a variety of autorefractors, VA measurements tend to be worse with autorefraction than manual refraction. Differences between individual autorefractor models were identified. However, even among autorefractor models comparing most favorably to manual refraction, VA variability between autorefraction and manual refraction is higher than the test-retest variability of manual refraction. The results suggest that with current instruments, autorefraction is not an acceptable substitute for manual refraction for most clinical trials with primary outcomes dependent on best-corrected VA. PMID:22159173

The Evolution of Extravehicular Activity Operations to Lunar Exploration Based on Operational Lessons Learned During 2009 NASA Desert RATS Field Testing

NASA Technical Reports Server (NTRS)

Bell, Ernest R., Jr.; Welsh, Daren; Coan, Dave; Johnson, Kieth; Ney, Zane; McDaniel, Randall; Looper, Chris; Guirgis, Peggy

2010-01-01

This paper will present options to evolutionary changes in several philosophical areas of extravehicular activity (EVA) operations. These areas will include single person verses team EVAs; various loss of communications scenarios (with Mission Control, between suited crew, suited crew to rover crew, and rover crew A to rover crew B); EVA termination and abort time requirements; incapacitated crew ingress time requirements; autonomous crew operations during loss of signal periods including crew decisions on EVA execution (including decision for single verses team EVA). Additionally, suggestions as to the evolution of the make-up of the EVA flight control team from the current standard will be presented. With respect to the flight control team, the major areas of EVA flight control, EVA Systems and EVA Tasks, will be reviewed, and suggested evolutions of each will be presented. Currently both areas receive real-time information, and provide immediate feedback during EVAs as well as spacesuit (extravehicular mobility unit - EMU) maintenance and servicing periods. With respect to the tasks being performed, either EMU servicing and maintenance, or the specific EVA tasks, daily revising of plans will need to be able to be smoothly implemented to account for unforeseen situations and findings. Many of the presented ideas are a result of lessons learned by the NASA Johnson Space Center Mission Operations Directorate operations team support during the 2009 NASA Desert Research and Technology Studies (Desert RATS). It is important that the philosophy of both EVA crew operations and flight control be examined now, so that, where required, adjustments can be made to a next generation EMU and EVA equipment that will complement the anticipated needs of both the EVA flight control team and the crews.

Advanced development of non-discoloring EVA-based PV encapsulants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holley, W.H.; Galica, J.P.; Argo, S.C.

1996-01-01

The purpose of this investigation was to better define the problem of field yellowing of EVA-based PV encapsulant, through laboratory study of probable chemical mechanisms and the development of stabilization strategies for protecting EVA from discoloration. EVA from fielded modules was analyzed for vinyl acetate content, unsaturation, and additive levels. These test results were then compared to results from Xenon Arc Weather-Ometer aged glass/EVA/glass laminates made in the laboratory. Variables evaluated in Weather-Ometer aged laminates included ``standard-cure`` A9918P EVA, ``fast-cure`` 15295P EVA, low iron glass superstrate containing cerium oxide, and systematic elimination or addition of specific additives. Six significant findingsmore » were revealed: 1) Improved ``standard-cure`` and ``fast-cure`` type EVA encapsulants, formulations X9903P and X15303P, respectively, showed little or no yellowing after extended Weather-Ometer exposure; 2) The use of {open_quote}{open_quote}fast-cure{close_quote}{close_quote} EVA reduced discoloration when compared with {open_quote}{open_quote}standard-cure{close_quote}{close_quote} A9918P EVA; 3) Glass superstrate containing cerium oxide resulted in a reduced rate of EVA discoloration; 4) {open_quote}{open_quote}Fast-cure{close_quote}{close_quote} EVA used with glass superstrate containing cerium oxide showed no visible yellowing after 32 weeks in the Weather-Ometer{emdash}a period estimated to be roughly equivalent to 20{endash}30 years of exposure in the Southwest; 5) Severely discolored EVA samples from the field showed no measurable loss of acetate group and little detectable unsaturation; and 6) EVA encapsulant with a Tefzel cover exhibited no yellowing after extended Weather-Ometer exposure. {copyright} {ital 1996 American Institute of Physics.}« less

Adhesion Strength Study of EVA Encapsulants on Glass Substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F. J.; Glick, S. H.

2003-05-01

An extensive peel-test study was conducted to investigate the various factors that may affect the adhesion strength of photovoltaic module encapsulants, primarily ethylene-vinyl acetate (EVA), on glass substrates of various laminates based on a common configuration of glass/encapsulant/backfoil. The results show that"pure" or"absolute" adhesion strength of EVA-to-glass was very difficult to obtain because of tensile deformation of the soft, semi-elastic EVA layer upon pulling. A mechanically"strong enough" backing foil on the EVA was critical to achieving the"apparent" adhesion strength. Peel test method with a 90-degree-pull yielded similar results to a 180-degree-pull. The 90-degree-pull method better revealed the four stages ofmore » delamination failure of the EVA/backfoil layers. The adhesion strength is affected by a number of factors, which include EVA type, formulation, backfoil type and manufacturing source, glass type, and surface priming treatment on the glass surface or on the backfoil. Effects of the glass-cleaning method and surface texture are not obvious. Direct priming treatments used in the work did not improve, or even worsened, the adhesion. Aging of EVA by storage over~5 years reduced notably the adhesion strength. Lower adhesion strengths were observed for the blank (unformulated) EVA and non-EVA copolymers, such as poly(ethylene-co-methacrylate) (PEMA) or poly(ethylene-co-butylacrylate) (PEBA). Their adhesion strengths increased if the copolymers were cross-linked. Transparent fluoropolymer superstrates such as TefzelTM and DureflexTM films used for thin-film PV modules showed low adhesion strengths to the EVA at a level of~2 N/mm.« less

EVA Health and Human Performance Benchmarking Study

NASA Technical Reports Server (NTRS)

Abercromby, A. F.; Norcross, J.; Jarvis, S. L.

2016-01-01

Multiple HRP Risks and Gaps require detailed characterization of human health and performance during exploration extravehicular activity (EVA) tasks; however, a rigorous and comprehensive methodology for characterizing and comparing the health and human performance implications of current and future EVA spacesuit designs does not exist. This study will identify and implement functional tasks and metrics, both objective and subjective, that are relevant to health and human performance, such as metabolic expenditure, suit fit, discomfort, suited postural stability, cognitive performance, and potentially biochemical responses for humans working inside different EVA suits doing functional tasks under the appropriate simulated reduced gravity environments. This study will provide health and human performance benchmark data for humans working in current EVA suits (EMU, Mark III, and Z2) as well as shirtsleeves using a standard set of tasks and metrics with quantified reliability. Results and methodologies developed during this test will provide benchmark data against which future EVA suits, and different suit configurations (eg, varied pressure, mass, CG) may be reliably compared in subsequent tests. Results will also inform fitness for duty standards as well as design requirements and operations concepts for future EVA suits and other exploration systems.

Generic extravehicular (EVA) and telerobot task primitives for analysis, design, and integration. Version 1.0: Reference compilation for the EVA and telerobotics communities

NASA Technical Reports Server (NTRS)

Smith, Jeffrey H.; Drews, Michael

1990-01-01

The results are described of an effort to establish commonality and standardization of generic crew extravehicular (crew-EVA) and telerobotic task analysis primitives used for the study of spaceborne operations. Although direct crew-EVA plans are the most visible output of spaceborne operations, significant ongoing efforts by a wide variety of projects and organizations also require tools for estimation of crew-EVA and telerobotic times. Task analysis tools provide estimates for input to technical and cost tradeoff studies. A workshop was convened to identify the issues and needs to establish a common language and syntax for task analysis primitives. In addition, the importance of such a syntax was shown to have precedence over the level to which such a syntax is applied. The syntax, lists of crew-EVA and telerobotic primitives, and the data base in diskette form are presented.

Preparation, characterization and application of EVA film containing Eu3+ complex with 1-tridecanecarboxylic acid ligand

NASA Astrophysics Data System (ADS)

Dong, Jin; Lin, Baoping

2017-11-01

In this study, on the basis of complex Eu(DBM)3Phen which was widely applied in polymer matrices, quaternary complex Eu(DBM)2Phen(TA) was synthesized by the introduction of 1-tridecanecarboxylic acid (TA). XRD analyses show that Eu(DBM)2Phen(TA) inclines to amorphization compared with Eu(DBM)3Phen which is crystal. Ethylene-vinyl acetate (EVA) film doped with Eu(DBM)2Phen(TA) was prepared by casting method. SEM and AFM analyses show that the compatibility of Eu(DBM)2Phen(TA) with EVA is better than that of Eu(DBM)3Phen with EVA. Under the same addition amount of Eu3+ complexes, visible light transmittance of Eu(DBM)2Phen(TA)/EVA film is obviously greater than that of Eu(DBM)3Phen/EVA film, and the fluorescence intensity of Eu(DBM)2Phen(TA)/EVA film is only slightly lower than that of Eu(DBM)3Phen/EVA film. With the optimum addition amount of Eu3+ complexes, the energy conversion efficiency of the polycrystalline silicon solar cell coated with Eu(DBM)2Phen(TA)/EVA film is improved to 12.14%, and in comparison, that of the solar cell coated with Eu(DBM)3Phen/EVA film is only 11.98%. Hence Eu(DBM)2Phen(TA)/EVA film has a potential prospect as luminescent down-shifting material.

Self-Control and Emotional and Verbal Aggression in Dating Relationships: A Dyadic Understanding.

PubMed

Baker, Elizabeth A; Klipfel, Katherine M; van Dulmen, Manfred H M

2016-08-01

Guided by the dynamic developmental systems perspective, this study extends past research by examining the association between self-control and emotional and verbal aggression (EVA) using a dyadic multi-method design. Guided by empirical research and the dynamic developmental systems perspective, we hypothesized that (a) there would be a negative association between one's own self-control and one's own perpetration of EVA and (b) there would also be a negative association between one's partner's self-control and one's own perpetration of EVA. One hundred twenty heterosexual dating couples (ages 18-25 years) provided data on self-control (Grasmick et al.'s Low Self-Control Scale; reverse scored for ease of interpretation), self-reported perpetration of EVA (Emotional and Verbal Abuse subscale of the Conflict in Adolescent Dating Relationships Inventory), and observationally assessed perpetration of EVA. Data were analyzed using path analyses within the Actor-Partner Interdependence Model (APIM) framework. Consistent with previous findings, we found that self-control was negatively associated with the perpetration of EVA. Furthermore, we found partner effects, such that female-but not male-self-control predicted partner-observed perpetration of EVA. These findings highlight the importance of examining risk factors for EVA of both partners. Our findings also suggest that the association between self-control and EVA is partially a function of whether EVA is assessed through self-report or observational methodology. This highlights the need to conduct multi-method assessments in future research. As discussed in the article, our findings have implications for theories on intimate partner violence, study designs, and couple interventions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Glick, S.H.; Czanderna, A.W.

The stabilization effects of various superstrate materials against UV-induced EVA discoloration and the effect of photocurrent enhancement by white light-reflecting substrates are summarized. Based on the results, some alternative PV module encapsulation schemes are proposed for improved module performance, where the current or modified formulations of EVA encapsulants still can be used so that the typical processing tools and conditions need not to be changed significantly. The schemes are designed in an attempt to eliminate or minimize the EVA yellow-browning and to increase the module power output. Four key experimental results from the studies of EVA discoloration and encapsulation aremore » to employ: (1) UV-absorbing (filtering) glasses as superstrates to protect EVA from UV-induced discoloration, (2) gas-permeable polymer films as superstrates and/or substrates to prevent EVA yellowing by permitting photobleaching reactions, (3) modified EVA formulations, and (4) internal reflection of the light by white substrates. {copyright} {ital 1996 American Institute of Physics.}« less

Extravehicular activities limitations study. Volume 2: Establishment of physiological and performance criteria for EVA gloves

NASA Technical Reports Server (NTRS)

Ohara, John M.; Briganti, Michael; Cleland, John; Winfield, Dan

1988-01-01

One of the major probelms faced in Extravehicular Activity (EVA) glove development has been the absence of concise and reliable methods to measure the effects of EVA gloves on human hand capabilities. This report describes the development of a standardized set of tests designed to assess EVA-gloved hand capabilities in six measurement domains: Range of Motion, Strength, Tactile Perception, Dexterity, Fatigue, and Comfort. Based on an assessment of general human hand functioning and EVA task requirements several tests within each measurement domain were developed to provide a comprehensive evaluation. All tests were designed to be conducted in a glove box with the bare hand as a baseline and the EVA glove at operating pressure. A test program was conducted to evaluate the tests using a representative EVA glove. Eleven test subjects participated in a repeated-measures design. The report presents the results of the tests in each capability domain.

Correlation between surface carbon concentration and adhesive strength at the Si cell/EVA interface in a PV module

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhere, N.G.; Wollam, M.E.; Gadre, K.S.

1997-12-31

Silicon solar cell/EVA composite is being studied with an objective to further improve the manufacturing technology of PV modules. Sample extraction and adhesion strength measurement process has been modified. Silicon and EVA samples were extracted from solar cells of new and field-deployed modules. Optical microscopy, SEM, and AES of samples from new modules revealed EVA islands covering most of the silicon cell surface indicating a cohesive failure. A good correlation was observed between the adhesive strength and surface concentration of carbon. A low carbon concentration which indicated less EVA clinging to cell surface always resulted in low adhesive strengths. Themore » correlation provides a simple technique for inferring properties of EVA.« less

Collaborative Human Engineering Work in Space Exploration Extravehicular Activities (EVA)

NASA Technical Reports Server (NTRS)

DeSantis, Lena; Whitmore, Mihriban

2007-01-01

A viewgraph presentation on extravehicular activities in space exploration in collaboration with other NASA centers, industries, and universities is shown. The topics include: 1) Concept of Operations for Future EVA activities; 2) Desert Research and Technology Studies (RATS); 3) Advanced EVA Walkback Test; 4) Walkback Subjective Results; 5) Integrated Suit Test 1; 6) Portable Life Support Subsystem (PLSS); 7) Flex PLSS Design Process; and 8) EVA Information System; 9)

Advanced extravehicular activity systems requirements definition study. Phase 2: Extravehicular activity at a lunar base

NASA Technical Reports Server (NTRS)

Neal, Valerie; Shields, Nicholas, Jr.; Carr, Gerald P.; Pogue, William; Schmitt, Harrison H.; Schulze, Arthur E.

1988-01-01

The focus is on Extravehicular Activity (EVA) systems requirements definition for an advanced space mission: remote-from-main base EVA on the Moon. The lunar environment, biomedical considerations, appropriate hardware design criteria, hardware and interface requirements, and key technical issues for advanced lunar EVA were examined. Six remote EVA scenarios (three nominal operations and three contingency situations) were developed in considerable detail.

EVA - Don't Leave Earth Without It

NASA Technical Reports Server (NTRS)

Cupples, J. Scott; Smith, Stephen A.

2011-01-01

Modern manned space programs come in two categories: those that need Extravehicular Activity (EVA) and those that will need EVA. This paper discusses major milestones in the Shuttle Program where EVA was used to save payloads, enhance on-orbit capabilities, and build structures in order to ensure success of National Aeronautics and Space Administration (NASA) missions. In conjunction, the Extravehicular Mobility Unit s (EMU) design, and hence, its capabilities evolved as its mission evolved. It is the intent that lessons can be drawn from these case studies so that EVA compatibility is designed into future vehicles and payloads.

An Experimental Investigation of Dextrous Robots Using EVA Tools and Interfaces

NASA Technical Reports Server (NTRS)

Ambrose, Robert; Culbert, Christopher; Rehnmark, Frederik

2001-01-01

This investigation of robot capabilities with extravehicular activity (EVA) equipment looks at how improvements in dexterity are enabling robots to perform tasks once thought to be beyond machines. The approach is qualitative, using the Robonaut system at the Johnson Space Center (JSC), performing task trials that offer a quick look at this system's high degree of dexterity and the demands of EVA. Specific EVA tools attempted include tether hooks, power torque tools, and rock scoops, as well as conventional tools like scissors, wire strippers, forceps, and wrenches. More complex EVA equipment was also studied, with more complete tasks that mix tools, EVA hand rails, tethers, tools boxes, PIP pins, and EVA electrical connectors. These task trials have been ongoing over an 18 month period, as the Robonaut system evolved to its current 43 degree of freedom (DOF) configuration, soon to expand to over 50. In each case, the number of teleoperators is reported, with rough numbers of attempts and their experience level, with a subjective difficulty rating assigned to each piece of EVA equipment and function. JSC' s Robonaut system was successful with all attempted EVA hardware, suggesting new options for human and robot teams working together in space.

Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT)

NASA Technical Reports Server (NTRS)

Brown, Cheryl B.; Conger, Bruce C.; Miranda, Bruno M.; Bue, Grant C.; Rouen, Michael N.

2007-01-01

An effort was initiated by NASA/JSC in 2001 to develop an Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT) for the sizing of Extravehicular Activity System (EVAS) architecture and studies. Its intent was to support space suit development efforts and to aid in conceptual designs for future human exploration missions. Its basis was the Life Support Options Performance Program (LSOPP), a spacesuit and portable life support system (PLSS) sizing program developed for NASA/JSC circa 1990. EVAS_SAT estimates the mass, power, and volume characteristics for user-defined EVAS architectures, including Suit Systems, Airlock Systems, Tools and Translation Aids, and Vehicle Support equipment. The tool has undergone annual changes and has been updated as new data have become available. Certain sizing algorithms have been developed based on industry standards, while others are based on the LSOPP sizing routines. The sizing algorithms used by EVAS_SAT are preliminary. Because EVAS_SAT was designed for use by members of the EVA community, subsystem familiarity on the part of the intended user group and in the analysis of results is assumed. The current EVAS_SAT is operated within Microsoft Excel 2003 using a Visual Basic interface system.

Cluster-based exposure variation analysis

PubMed Central

2013-01-01

Background Static posture, repetitive movements and lack of physical variation are known risk factors for work-related musculoskeletal disorders, and thus needs to be properly assessed in occupational studies. The aims of this study were (i) to investigate the effectiveness of a conventional exposure variation analysis (EVA) in discriminating exposure time lines and (ii) to compare it with a new cluster-based method for analysis of exposure variation. Methods For this purpose, we simulated a repeated cyclic exposure varying within each cycle between “low” and “high” exposure levels in a “near” or “far” range, and with “low” or “high” velocities (exposure change rates). The duration of each cycle was also manipulated by selecting a “small” or “large” standard deviation of the cycle time. Theses parameters reflected three dimensions of exposure variation, i.e. range, frequency and temporal similarity. Each simulation trace included two realizations of 100 concatenated cycles with either low (ρ = 0.1), medium (ρ = 0.5) or high (ρ = 0.9) correlation between the realizations. These traces were analyzed by conventional EVA, and a novel cluster-based EVA (C-EVA). Principal component analysis (PCA) was applied on the marginal distributions of 1) the EVA of each of the realizations (univariate approach), 2) a combination of the EVA of both realizations (multivariate approach) and 3) C-EVA. The least number of principal components describing more than 90% of variability in each case was selected and the projection of marginal distributions along the selected principal component was calculated. A linear classifier was then applied to these projections to discriminate between the simulated exposure patterns, and the accuracy of classified realizations was determined. Results C-EVA classified exposures more correctly than univariate and multivariate EVA approaches; classification accuracy was 49%, 47% and 52% for EVA (univariate and multivariate), and C-EVA, respectively (p < 0.001). All three methods performed poorly in discriminating exposure patterns differing with respect to the variability in cycle time duration. Conclusion While C-EVA had a higher accuracy than conventional EVA, both failed to detect differences in temporal similarity. The data-driven optimality of data reduction and the capability of handling multiple exposure time lines in a single analysis are the advantages of the C-EVA. PMID:23557439

Extravehicular Activity (EVA) Hardware & Operations Overview

NASA Technical Reports Server (NTRS)

Moore, Sandra; Marmolejo, Jose

2014-01-01

The objectives of this presentation are to: Define Extravehicular Activity (EVA), identify the reasons for conducting an EVA, and review the role that EVA has played in the space program; Identify the types of EVAs that may be performed; Describe some of the U.S. Space Station equipment and tools that are used during an EVA, such as the Extravehicular Mobility Unit (EMU), the Simplified Aid For EVA Rescue (SAFER), the International Space Station (ISS) Joint Airlock and Russian Docking Compartment 1 (DC-1), and EVA Tools & Equipment; Outline the methods and procedures of EVA Preparation, EVA, and Post-EVA operations; Describe the Russian spacesuit used to perform an EVA; Provide a comparison between U.S. and Russian spacesuit hardware and EVA support; and Define the roles that different training facilities play in EVA training.

A Human Factors Analysis of EVA Time Requirements

NASA Technical Reports Server (NTRS)

Pate, Dennis W.

1997-01-01

Human Factors Engineering (HFE) is a discipline whose goal is to engineer a safer, more efficient interface between humans and machines. HFE makes use of a wide range of tools and techniques to fulfill this goal. One of these tools is known as motion and time study, a technique used to develop time standards for given tasks. During the summer of 1995, a human factors motion and time study was initiated with the goals of developing a database of EVA task times and developing a method of utilizing the database to predict how long an EVA should take. Initial development relied on the EVA activities performed during the STS-61 (Hubble) mission. The first step of the study was to become familiar with EVA's, the previous task-time studies, and documents produced on EVA's. After reviewing these documents, an initial set of task primitives and task-time modifiers was developed. Data was collected from videotaped footage of two entire STS-61 EVA missions and portions of several others, each with two EVA astronauts. Feedback from the analysis of the data was used to further refine the primitives and modifiers used. The project was continued during the summer of 1996, during which data on human errors was also collected and analyzed. Additional data from the STS-71 mission was also collected. Analysis of variance techniques for categorical data was used to determine which factors may affect the primitive times and how much of an effect they have. Probability distributions for the various task were also generated. Further analysis of the modifiers and interactions is planned.

Evaluation of visual acuity measurements after autorefraction vs manual refraction in eyes with and without diabetic macular edema.

PubMed

Sun, Jennifer K; Qin, Haijing; Aiello, Lloyd Paul; Melia, Michele; Beck, Roy W; Andreoli, Christopher M; Edwards, Paul A; Glassman, Adam R; Pavlica, Michael R

2012-04-01

To compare visual acuity (VA) scores after autorefraction vs manual refraction in eyes of patients with diabetes mellitus and a wide range of VAs. The letter score from the Electronic Visual Acuity (EVA) test from the electronic Early Treatment Diabetic Retinopathy Study was measured after autorefraction (AR-EVA score) and after manual refraction (MR-EVA score), which is the research protocol of the Diabetic Retinopathy Clinical Research Network. Testing order was randomized, study participants and VA examiners were masked to refraction source, and a second EVA test using an identical supplemental manual refraction (MR-EVAsuppl score) was performed to determine test-retest variability. In 878 eyes of 456 study participants, the median MR-EVA score was 74 (Snellen equivalent, approximately 20/32). The spherical equivalent was often similar for manual refraction and autorefraction (median difference, 0.00; 5th-95th percentile range, -1.75 to 1.13 diopters). However, on average, the MR-EVA scores were slightly better than the AR-EVA scores, across the entire VA range. Furthermore, the variability between the AR-EVA scores and the MR-EVA scores was substantially greater than the test-retest variability of the MR-EVA scores (P < .001). The variability of differences was highly dependent on the autorefractor model. Across a wide range of VAs at multiple sites using a variety of autorefractors, VA measurements tend to be worse with autorefraction than manual refraction. Differences between individual autorefractor models were identified. However, even among autorefractor models that compare most favorably with manual refraction, VA variability between autorefraction and manual refraction is higher than the test-retest variability of manual refraction. The results suggest that, with current instruments, autorefraction is not an acceptable substitute for manual refraction for most clinical trials with primary outcomes dependent on best-corrected VA.

Asteroid Redirect Crewed Mission Space Suit and EVA System Architecture Trade Study

NASA Technical Reports Server (NTRS)

Blanco, Raul A.; Bowie, Jonathan T.; Watson, Richard D.; Sipila, Stephanie A.

2014-01-01

The Asteroid Redirect Crewed Mission (ARCM) requires a Launch/Entry/Abort (LEA) suit capability and short duration Extra Vehicular Activity (EVA) capability for Orion. The EVAs will involve a two-person crew for approximately four hours. Currently, two EVAs are planned with one contingency EVA in reserve. Providing this EVA capability is very challenging due to system level constraints and a new and unknown environment. The goal of the EVA architecture for ARCM is one that builds upon previously developed technologies and lessons learned, and that accomplishes the ARCM mission while providing a stepping stone to future missions and destinations. The primary system level constraints are to 1) minimize system mass and volume and 2) minimize the interfacing impacts to the baseline Orion design. In order to minimize the interfacing impacts and to not perturb the baseline Orion schedule, the concept of adding "kits" to the baseline system is proposed. These kits consist of: an EVA kit (converts LEA suit to EVA suit), EVA Servicing and Recharge Kit (provides suit consumables), the EVA Tools, Translation Aids & Sample Container Kit (the tools and mobility aids to complete the tasks), the EVA Communications Kit (interface between the EVA radio and the MPCV), and the Cabin Repress Kit (represses the MPCV between EVAs). This paper will focus on the trade space, analysis, and testing regarding the space suit (pressure garment and life support system). Historical approaches and lessons learned from all past EVA operations were researched. Previous and current, successfully operated EVA hardware and high technology readiness level (TRL) hardware were evaluated, and a trade study was conducted for all possible pressure garment and life support options. Testing and analysis was conducted and a recommended EVA system architecture was proposed. Pressure garment options that were considered for this mission include the currently in-use ISS EVA Mobility Unit (EMU), all variations of the Advanced Crew Escape Suit (ACES), and the Exploration Z-suit. For this mission, the pressure garment that was selected is the Modified ACES (MACES) with EVA enhancements. Life support options that were considered included short closed-loop umbilicals, long open-loop umbilicals, the currently in-use ISS EMU Portable Life Support System (PLSS), and the currently in development Exploration PLSS. For this mission, the life support option that was selected is the Exploration PLSS. The greatest risk in the proposed architecture is viewed to be the comfort and mobility of the baseline MACES and the delicate balance between adding more mobility features while not compromising landing safety. Feasibility testing was accomplished in low fidelity analogs and in the JSC Neutral Buoyancy Laboratory (NBL) to validate the concept before a final recommendation on the architecture was made. The proposed architecture was found to meet the mission constraints, but much more work is required to determine the details of the required suit upgrades, the integration with the PLSS, and the rest of the tools and equipment required to accomplish the mission. This work and further definition of the remaining kits will be conducted in government fiscal year 14.

Eva Physiology, Systems, and Performance (EPSP) Project Overview

NASA Technical Reports Server (NTRS)

Gernhardt, Michael L.

2007-01-01

Extravehicular activity (EVA) is any activity performed by astronauts outside their space vehicle or habitat. EVA may be performed on orbit, such as outside the Space Shuttle or the International Space Station, or on a planetary surface such as Mars or on the moon. Astronauts wear a pressurized suit that provides environmental protection, mobility, life support, and communications while they work in the harsh conditions of a microgravity environment. Exploration missions to the moon and Mars may last many days and will include many types of EVAs; exploration, science, construction and maintenance. The effectiveness and success of these EVA-filled missions is dependent on the ability to perform tasks efficiently. The EVA Physiology, Systems and Performance (EPSP) project will conduct a number of studies to understand human performance during EVA, from a molecular level to full-scale equipment and suit design aspects, with the aim of developing safe and efficient systems for Exploration missions and the Constellation Program. The EPSP project will 1) develop Exploration Mission EVA suit requirements for metabolic and thermal loading, optional center of gravity location, biomedical sensors, hydration, nutrition, and human biomedical interactions; 2) develop validated EVA prebreathe protocols that meet medical, vehicle, and habitat constraints while minimizing crew time and thus increasing EVA work efficiency; and 3) define exploration decompression sickness (DCS) risks, policy, and mission success statistics and develop a DCS risk definition report.

Extravehicular Activity Asteroid Exploration and Sample Collection Capability

NASA Technical Reports Server (NTRS)

Sipila, Stephanie A.; Scoville, Zebulon C.; Bowie, Jonathan T.; Buffington, Jesse A.

2014-01-01

One of the challenging primary objectives associated with NASA's Asteroid Redirect Crewed Mission (ARCM) is to demonstrate deep space Extravehicular Activity (EVA) and tools and to obtain asteroid samples to return to Earth for further study. Prior Shuttle and International Space Station (ISS) spacewalks have benefited from engineered EVA interfaces which have been designed and manufactured on Earth. Rigid structurally mounted handrails, and tools with customized interfaces and restraints optimize EVA performance. For ARCM, EVA complexity increases due to the uncertainty of the asteroid properties. The variability of rock size, shape and composition, as well as behavior of the asteroid capture mechanism will complicate EVA translation, tool restraint, and body stabilization. The unknown asteroid hardness and brittleness will complicate tool use. The rock surface will introduce added safety concerns for cut gloves and debris control. Feasible solutions to meet ARCM EVA objectives were identified using experience gained during Apollo, Shuttle, and ISS EVAs, terrestrial mountaineering practices, NASA Extreme Environment Mission Operations (NEEMO) 16 mission, and during Neutral Buoyancy Laboratory testing in the Modified Advanced Crew Escape Suit (MACES) suit. This paper will summarize the overall operational concepts for conducting EVAs for the ARCM mission including translation paths and body restraint methods, potential tools used to extract the samples, design implications for the Asteroid Redirect Vehicle (ARV) for EVA, and the results of early development testing of potential EVA tasks.

EVA: laparoscopic instrument tracking based on Endoscopic Video Analysis for psychomotor skills assessment.

PubMed

Oropesa, Ignacio; Sánchez-González, Patricia; Chmarra, Magdalena K; Lamata, Pablo; Fernández, Alvaro; Sánchez-Margallo, Juan A; Jansen, Frank Willem; Dankelman, Jenny; Sánchez-Margallo, Francisco M; Gómez, Enrique J

2013-03-01

The EVA (Endoscopic Video Analysis) tracking system is a new system for extracting motions of laparoscopic instruments based on nonobtrusive video tracking. The feasibility of using EVA in laparoscopic settings has been tested in a box trainer setup. EVA makes use of an algorithm that employs information of the laparoscopic instrument's shaft edges in the image, the instrument's insertion point, and the camera's optical center to track the three-dimensional position of the instrument tip. A validation study of EVA comprised a comparison of the measurements achieved with EVA and the TrEndo tracking system. To this end, 42 participants (16 novices, 22 residents, and 4 experts) were asked to perform a peg transfer task in a box trainer. Ten motion-based metrics were used to assess their performance. Construct validation of the EVA has been obtained for seven motion-based metrics. Concurrent validation revealed that there is a strong correlation between the results obtained by EVA and the TrEndo for metrics, such as path length (ρ = 0.97), average speed (ρ = 0.94), or economy of volume (ρ = 0.85), proving the viability of EVA. EVA has been successfully validated in a box trainer setup, showing the potential of endoscopic video analysis to assess laparoscopic psychomotor skills. The results encourage further implementation of video tracking in training setups and image-guided surgery.

Immunodominant IgM and IgG Epitopes Recognized by Antibodies Induced in Enterovirus A71-Associated Hand, Foot and Mouth Disease Patients

PubMed Central

Aw-Yong, Kam Leng; Sam, I-Ching; Koh, Mia Tuang

2016-01-01

Enterovirus A71 (EV-A71) is one of the main causative agents of hand, foot and mouth disease (HFMD). Unlike other enteroviruses that cause HFMD, EV-A71 is more frequently associated with severe neurological complications and fatality. To date, no effective licensed antivirals are available to combat EV-A71 infection. Little is known about the immunogenicity of viral non-structural proteins in humans. Previous studies have mainly focused on characterization of epitopes of EV-A71 structural proteins by using immunized animal antisera. In this study, we have characterized human antibody responses against the structural and non-structural proteins of EV-A71. Each viral protein was cloned and expressed in either bacterial or mammalian systems, and tested with antisera by western blot. Results revealed that all structural proteins (VP1-4), and non-structural proteins 2A, 3C and 3D were targets of EV-A71 IgM, whereas EV-A71 IgG recognized all the structural and non-structural proteins. Sixty three synthetic peptides predicted to be immunogenic in silico were synthesized and used for the characterization of EV-A71 linear B-cell epitopes. In total, we identified 22 IgM and four IgG dominant epitopes. Synthetic peptide PEP27, corresponding to residues 142–156 of VP1, was identified as the EV-A71 IgM-specific immunodominant epitope. PEP23, mapped to VP1 41–55, was recognized as the EV-A71 IgG cross-reactive immunodominant epitope. The structural protein VP1 is the major immunodominant site targeted by anti-EV-A71 IgM and IgG antibodies, but epitopes against non-structural proteins were also detected. These data provide new understanding of the immune response to EV-A71 infection, which benefits the development of diagnostic tools, potential therapeutics and subunit vaccine candidates. PMID:27806091

Mechanical behaviour study on SBR/EVA composite for FDM feedstock fabrication

NASA Astrophysics Data System (ADS)

Raveverma, P.; Ibrahim, M.; Sa'ude, N.; Yarwindran, M.; Nasharuddin, M.

2017-04-01

This paper presents the research development of a new SBR/EVA composite flexible feedstock material by the injection moulding machine. The material consists of poly (ethylene-co-vinyl acetate) in styrene butadiene rubber cross-linked by Dicumyl Peroxide. In this study, the mechanical behaviour of injection moulded SBR/EVA composite with different blend ratio investigated experimentally. The formulations of blend ratio with several combinations of a new SBR/EVA flexible feedstock was done by volume percentage (vol. %). Based on the result obtained from the mechanical testing done which is tensile and hardness the composite of SBR/EVA has the high potency to be fabricated as the flexible filament feedstock. The ratio of 80:20 which as an average hardness and tensile strength proved to be the suitable choice to be fabricated as the flexible filament feedstock. The study has reached its goals on the fabricating and testing a new PMC which is flexible.

Study of space shuttle EVA/IVA support requirements. Volume 2: EVA/IVA tasks, guidelines, and constraints definition

NASA Technical Reports Server (NTRS)

Webbon, B. W.; Copeland, R. J.; Wood, P. W., Jr.; Cox, R. L.

1973-01-01

The guidelines for EVA and IVA tasks to be performed on the space shuttle are defined. In deriving tasks, guidelines, and constraints, payloads were first identified from the mission model. Payload requirements, together with man and manipulator capabilities, vehicle characteristics and operation, and safety considerations led to a definition of candidate tasks. Guidelines and constraints were also established from these considerations. Scenarios were established, and screening criteria, such as commonality of EVA and IVA activities, were applied to derive representative planned and unplanned tasks. The whole spectrum of credible contingency situations with a potential requirement for EVA/IVA was analyzed.

Morphological and Mechanical Properties of Polypropylene[PP]/Poly(Ethylene Vinyl Acetate)[EVA] Blends. I. Homopolymer PP/Eva Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramirez-Vargas, E.

2000-10-01

Morphological and mechanical properties of polypropylene [PP]/poly(ethylene vinyl acetate) [EVA] blends have been studied. Infrared results using thin films first indicated a transition toward compatibility between both components at concentrations above 40% EVA. The transition was verified with different experimental techniques and it was associated to morphological changes and mechanical properties. The PP/EVA blends were mechanically evaluated in terms of impact and tensile strength to determine the influence of blending on the performance properties of these materials. Agreement was found between the transition and the enhancement of both elongation at break and impact strength.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holley, W.H. Jr.; Agro, S.C.; Galica, J.P.

The problem of browning in a number of EVA encapsulated flat plate photovoltaic modules has led to the questioning of EVA as a suitable material for such applications. By isolating the variables that could possibly lead to EVA browning, such as module construction, types of glass superstrates, additives, and processing conditions, the authors have been able to determine those significant specific variables that seem to have the most influence on discoloration.When standard-cure EVA-based laminates were exposed to accelerated UV aging, measurable yellowing of those laminates was evident after only one to two weeks exposure, and visual discoloration was observed aftermore » four to six weeks. Some samples yellowed quickly and some not at all, and there were significant differences in the rates of discoloration between standard-cure and fast-cure EVA. This paper looks at the results of these studies, especially focusing on the effect of additives in the EVA on the rate of yellowing, and discusses how preliminary results can be used to reformulate EVA encapsulants.« less

Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA).

PubMed

Brancher, Luiza R; Nunes, Maria Fernanda de O; Grisa, Ana Maria C; Pagnussat, Daniel T; Zeni, Mára

2016-01-15

This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite.

Spaceborne construction and operations planning - Decision rules for selecting EVA, telerobot, and combined work-systems

NASA Technical Reports Server (NTRS)

Smith, Jeffrey H.

1992-01-01

An approach is presented for selecting an appropriate work-system for performing construction and operations tasks by humans and telerobots. The decision to use extravehicular activity (EVA) performed by astronauts, extravehicular robotics (EVR), or a combination of EVA and EVR is determined by the ratio of the marginal costs of EVA, EVR, and IVA. The approach proposed here is useful for examining cost trade-offs between tasks and performing trade studies of task improvement techniques (human or telerobotic).

EVA Human Health and Performance Benchmarking Study Overview and Development of a Microgravity Protocol

NASA Technical Reports Server (NTRS)

Norcross, Jason; Jarvis, Sarah; Bekdash, Omar; Cupples, Scott; Abercromby, Andrew

2017-01-01

The primary objective of this study is to develop a protocol to reliably characterize human health and performance metrics for individuals working inside various EVA suits under realistic spaceflight conditions. Expected results and methodologies developed during this study will provide the baseline benchmarking data and protocols with which future EVA suits and suit configurations (e.g., varied pressure, mass, center of gravity [CG]) and different test subject populations (e.g., deconditioned crewmembers) may be reliably assessed and compared. Results may also be used, in conjunction with subsequent testing, to inform fitness-for-duty standards, as well as design requirements and operations concepts for future EVA suits and other exploration systems.

Extravehicular Activity Asteroid Exploration and Sample Collection Capability

NASA Technical Reports Server (NTRS)

Scoville, Zebulon; Sipila, Stephanie; Bowie, Jonathan

2014-01-01

NASA's Asteroid Redirect Crewed Mission (ARCM) is challenged with primary mission objectives of demonstrating deep space Extravehicular Activity (EVA) and tools, and obtaining asteroid samples to return to Earth for further study. Although the Modified Advanced Crew Escape Suit (MACES) is used for the EVAs, it has limited mobility which increases fatigue and decreases the crews' capability to perform EVA tasks. Furthermore, previous Shuttle and International Space Station (ISS) spacewalks have benefited from EVA interfaces which have been designed and manufactured on Earth. Rigid structurally mounted handrails, and tools with customized interfaces and restraints optimize EVA performance. For ARCM, some vehicle interfaces and tools can leverage heritage designs and experience. However, when the crew ventures onto an asteroid capture bag to explore the asteroid and collect rock samples, EVA complexity increases due to the uncertainty of the asteroid properties. The variability of rock size, shape and composition, as well as bunching of the fabric bag will complicate EVA translation, tool restraint and body stabilization. The unknown asteroid hardness and brittleness will complicate tool use. The rock surface will introduce added safety concerns for cut gloves and debris control. Feasible solutions to meet ARCM EVA objectives were identified using experience gained during Apollo, Shuttle, and ISS EVAs, terrestrial mountaineering practices, NASA Extreme Environment Mission Operations (NEEMO) 16 mission, and during Neutral Buoyancy Laboratory testing in the MACES suit. The proposed concept utilizes expandable booms and integrated features of the asteroid capture bag to position and restrain the crew at the asteroid worksite. These methods enable the capability to perform both finesse, and high load tasks necessary to collect samples for scientific characterization of the asteroid. This paper will explore the design trade space and options that were examined for EVA, the overall concept for the EVAs including translation paths and body restraint methods, potential tools used to extract the samples, design implications for the Asteroid Redirect Vehicle (ARV) for EVA, the results of early development testing of potential EVA tasks, and extensibility of the EVA architecture to NASA's exploration missions.

Energy Expenditure During Extravehicular Activity: Apollo Skylab Through STS-135

NASA Technical Reports Server (NTRS)

Paul, Heather L.

2011-01-01

The importance of real-time metabolic rate monitoring during extravehicular activities (EVAs) came into question during the Gemini missions, when the energy expenditure required to conduct an EVA over-tasked the crewmember and exceeded the capabilities of vehicle and space suit life support systems. Energy expenditure was closely evaluated through the Apollo lunar surface EVAs, resulting in modifications to space suit design and EVA operations. After the Apollo lunar surface missions were completed, the United States shifted its focus to long duration human space flight, to study the human response to living and working in a microgravity environment. This paper summarizes the energy expenditure during EVA from Apollo Skylab through STS-135.

Preliminary Work Domain Analysis for Human Extravehicular Activity

NASA Technical Reports Server (NTRS)

McGuire, Kerry; Miller, Matthew; Feigh, Karen

2015-01-01

A work domain analysis (WDA) of human extravehicular activity (EVA) is presented in this study. A formative methodology such as Cognitive Work Analysis (CWA) offers a new perspective to the knowledge gained from the past 50 years of living and working in space for the development of future EVA support systems. EVA is a vital component of human spaceflight and provides a case study example of applying a work domain analysis (WDA) to a complex sociotechnical system. The WDA presented here illustrates how the physical characteristics of the environment, hardware, and life support systems of the domain guide the potential avenues and functional needs of future EVA decision support system development.

Clinically isolated enterovirus A71 subgenogroup C4 strain with lethal pathogenicity in 14-day-old mice and the application as an EV-A71 mouse infection model.

PubMed

Xu, Yi; Ma, Shuzhi; Zhu, Limeng; Huang, Zhiqiu; Chen, Liyun; Xu, Yuhua; Yin, Haibin; Peng, Tao; Wang, Yi

2017-01-01

The Enterovirus A71 (EV-A71) subgenogroup C4 is prevalent in China. EV-A71 causes hand, foot and mouth disease (HFMD) in children and may lead to severe neurological diseases. The development of antiviral and protective vaccines against EV-A71 is significantly hindered by the lack of suitable animal models to recapitulate human neurological symptoms. In this study, GZ-CII, a highly virulent EV-A71 subgenogroup C4 strain, was isolated from hospitalized children with HFMD. Intraperitoneal infections of GZ-CII resulted in progressive neurological disease in mice as old as 14 days. Administration of an inactivated EV-A71 vaccine or an anti-EV-A71 immune serum protected the mice against the GZ-CII infection. This demonstrated that a mouse model with EV-A71 GZ-CII could be used to evaluate potential vaccine candidates and therapeutics for subgenogroup C4. Comparing the genome sequence of GZ-CII with that of the avirulent EV-A71 subgenogroup C4 strain revealed unique mutations in GZ-CII. When mutation VP2-K149I was introduced into the nonpathogenic EV-A71 subgenogroup C4 strain, the variant similar to GZ-CII significantly increased viral replication and virulence in mice. These results indicated that the VP2-K149I mutation played an important role in enhancing the virulence of the EV-A71 subgenogroup C4 strain in mice, and that mice infected with the GZ-CII strain are a promising model for evaluating vaccines and therapeutics against the EV-A71 subgenogroup C4. Copyright © 2016 Elsevier B.V. All rights reserved.

Epidemiology of hand, foot and mouth disease in China, 2008 to 2015 prior to the introduction of EV-A71 vaccine.

PubMed

Yang, Bingyi; Liu, Fengfeng; Liao, Qiaohong; Wu, Peng; Chang, Zhaorui; Huang, Jiao; Long, Lu; Luo, Li; Li, Yu; Leung, Gabriel M; Cowling, Benjamin J; Yu, Hongjie

2017-12-01

Hand, foot and mouth disease (HFMD) is usually caused by several serotypes from human enterovirus A species, including enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16). Two inactivated monovalent EV-A71 vaccines have been recently licensed in China and monovalent CV-A16 vaccine and bivalent EV-A71 and CV-A16 vaccine are under development. Using notifications from the national surveillance system, we describe the epidemiology and dynamics of HFMD in the country, before the introduction of EV-A71 vaccination, from 2008 through 2015. Laboratory-identified serotype categories, i.e. CV-A16, EV-A71 and other enteroviruses, circulated annually. EV-A71 remained the most virulent serotype and was the major serotype for fatal cases (range: 88.5-95.4%) and severe cases (range: 50.7-82.3%) across years. Except for 2013 and 2015, when other enteroviruses were more frequently found in mild HFMD (48.8% and 52.5%), EV-A71 was more frequently detected from mild cases in the rest of the years covered by the study (range: 39.4-52.6%). The incidence rates and severity risks of HFMD associated with all serotype categories were the highest for children aged 1 year and younger, and decreased with increasing age. This study provides baseline epidemiology for evaluation of vaccine impact and potential serotype replacement.

Eva1 Maintains the Stem-like Character of Glioblastoma-Initiating Cells by Activating the Noncanonical NF-κB Signaling Pathway.

PubMed

Ohtsu, Naoki; Nakatani, Yuka; Yamashita, Daisuke; Ohue, Shiro; Ohnishi, Takanori; Kondo, Toru

2016-01-01

Glioblastoma (GBM)-initiating cells (GIC) are a tumorigenic subpopulation that are resistant to radio- and chemotherapies and are the source of disease recurrence. Therefore, the identification and characterization of GIC-specific factors is critical toward the generation of effective GBM therapeutics. In this study, we investigated the role of epithelial V-like antigen 1 (Eva1, also known as myelin protein zero-like 2) in stemness and GBM tumorigenesis. Eva1 was prominently expressed in GICs in vitro and in stem cell marker (Sox2, CD15, CD49f)-expressing cells derived from human GBM tissues. Eva1 knockdown in GICs reduced their self-renewal and tumor-forming capabilities, whereas Eva1 overexpression enhanced these properties. Eva1 deficiency was also associated with decreased expression of stemness-related genes, indicating a requirement for Eva1 in maintaining GIC pluripotency. We further demonstrate that Eva1 induced GIC proliferation through the activation of the RelB-dependent noncanonical NF-κB pathway by recruiting TRAF2 to the cytoplasmic tail. Taken together, our findings highlight Eva1 as a novel regulator of GIC function and also provide new mechanistic insight into the role of noncanonical NF-κB activation in GIC, thus offering multiple potential therapeutic targets for preclinical investigation in GBM. ©2015 American Association for Cancer Research.

EVA worksite analysis--use of computer analysis for EVA operations development and execution.

PubMed

Anderson, D

1999-01-01

To sustain the rate of extravehicular activity (EVA) required to assemble and maintain the International Space Station, we must enhance our ability to plan, train for, and execute EVAs. An underlying analysis capability has been developed to ensure EVA access to all external worksites as a starting point for ground training, to generate information needed for on-orbit training, and to react quickly to develop contingency EVA plans, techniques, and procedures. This paper describes the use of computer-based EVA worksite analysis techniques for EVA worksite design. EVA worksite analysis has been used to design 80% of EVA worksites on the U.S. portion of the International Space Station. With the launch of the first U.S. element of the station, EVA worksite analysis is being developed further to support real-time analysis of unplanned EVA operations. This paper describes this development and deployment of EVA worksite analysis for International Space Station (ISS) mission support.

Enterovirus A71 DNA-Launched Infectious Clone as a Robust Reverse Genetic Tool

PubMed Central

Tan, Chee Wah; Tee, Han Kang; Lee, Michelle Hui Pheng; Sam, I-Ching; Chan, Yoke Fun

2016-01-01

Enterovirus A71 (EV-A71) causes major outbreaks of hand, foot and mouth disease, and is occasionally associated with neurological complications and death in children. Reverse genetics is widely used in the field of virology for functional study of viral genes. For EV-A71, such tools are limited to clones that are transcriptionally controlled by T7/SP6 bacteriophage promoter. This is often time-consuming and expensive. Here, we describe the development of infectious plasmid DNA-based EV-A71 clones, for which EV-A71 genome expression is under transcriptional control by the CMV-intermediate early promoter and SV40 transcriptional-termination signal. Transfection of this EV-A71 infectious DNA produces good virus yield similar to in vitro-transcribed EV-A71 infectious RNA, 6.4 and 5.8 log10PFU/ml, respectively. Infectious plasmid with enhanced green fluorescence protein and Nano luciferase reporter genes also produced good virus titers, with 4.3 and 5.0 log10 PFU/ml, respectively. Another infectious plasmid with both CMV and T7 promoters was also developed for easy manipulation of in vitro transcription or direct plasmid transfection. Transfection with either dual-promoter infectious plasmid DNA or infectious RNA derived from this dual-promoter clone produced infectious viral particles. Incorporation of hepatitis delta virus ribozyme, which yields precise 3’ ends of the DNA-launched EV-A71 genomic transcripts, increased infectious viral production. In contrast, the incorporation of hammerhead ribozyme in the DNA-launched EV-A71 resulted in lower virus yield, but improved the virus titers for T7 promoter-derived infectious RNA. This study describes rapid and robust reverse genetic tools for EV-A71. PMID:27617744

Development of an EVA systems cost model. Volume 3: EVA systems cost model

NASA Technical Reports Server (NTRS)

1975-01-01

The EVA systems cost model presented is based on proposed EVA equipment for the space shuttle program. General information on EVA crewman requirements in a weightless environment and an EVA capabilities overview are provided.

Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA)

PubMed Central

Brancher, Luiza R.; Nunes, Maria Fernanda de O.; Grisa, Ana Maria C.; Pagnussat, Daniel T.; Zeni, Mára

2016-01-01

This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite. PMID:28787851

Operational Assessment of Apollo Lunar Surface Extravehicular Activity

NASA Technical Reports Server (NTRS)

Miller, Matthew James; Claybrook, Austin; Greenlund, Suraj; Marquez, Jessica J.; Feigh, Karen M.

2017-01-01

Quantifying the operational variability of extravehicular activity (EVA) execution is critical to help design and build future support systems to enable astronauts to monitor and manage operations in deep-space, where ground support operators will no longer be able to react instantly and manage execution deviations due to the significant communication latency. This study quantifies the operational variability exhibited during Apollo 14-17 lunar surface EVA operations to better understand the challenges and natural tendencies of timeline execution and life support system performance involved in surface operations. Each EVA (11 in total) is individually summarized as well as aggregated to provide descriptive trends exhibited throughout the Apollo missions. This work extends previous EVA task analyses by calculating deviations between planned and as-performed timelines as well as examining metabolic rate and consumables usage throughout the execution of each EVA. The intent of this work is to convey the natural variability of EVA operations and to provide operational context for coping with the variability inherent to EVA execution as a means to support future concepts of operations.

Compiling a Comprehensive EVA Training Dataset for NASA Astronauts

NASA Technical Reports Server (NTRS)

Laughlin, M. S.; Murry, J. D.; Lee, L. R.; Wear, M. L.; Van Baalen, M.

2016-01-01

Training for a spacewalk or extravehicular activity (EVA) is considered hazardous duty for NASA astronauts. This activity places astronauts at risk for decompression sickness as well as various musculoskeletal disorders from working in the spacesuit. As a result, the operational and research communities over the years have requested access to EVA training data to supplement their studies.

Evaluation of cardiac rhythm disturbances during extravehicular activity.

PubMed

Rossum, A C; Wood, M L; Bishop, S L; Deblock, H; Charles, J B

1997-04-15

This study represents the first systematic evaluation of dysrhythmias before, during, and after spaceflight including extravehicular activity (EVA). The data, based on 7 Shuttle crew members, revealed a nonsignificant decrease in ventricular and supraventricular ectopy during EVA, suggesting that the incidence of dysrhythmias is no greater during EVA than with any other phase of a mission or preflight.

Decision rules for spaceborne operations planning

NASA Technical Reports Server (NTRS)

Smith, Jeffrey H.

1992-01-01

Recent study of Space Station Freedom requirements for extravehicular activity (EVA) to perform external maintenance tasks emphasize an oversubscription of resources for performing on-orbit tasks. Extravehicular robotics (EVR) and cooperative EVA combined with EVR (using crew and robots synergistically to perform tasks) have been suggested as a part of the solution to reduce EVA. The question remains however, 'Under what conditions is it cost-effective to use the EVA and/or EVR resource.' The answer to such a question also has implications for the Space Station Freedom and its external maintenance as well as the Space Exploration Initiative (SEI) where the issue of work-system allocation is magnified by the long distances and scope of EVA work. This paper describes a simple technique of interest to operational planners and robot technology planners for determining in an economic context whether to use EVA alone, EVR alone, or Cooperative EVA. It is also shown that given: (1) the task times for these alternatives; and (2) the marginal costs of EVA, EVR, and IVA, the appropriate work system for performing the task can be identified. The paper illustrates how the work system choice is based on the ratio of costs. An example using Space Station Freedom data is presented to illustrate the trade-offs among alternative work-systems.

Shuttle EVA description and design criteria

NASA Technical Reports Server (NTRS)

1983-01-01

The STS extravehicular mobility unit, orbiter EVA provisions, EVA equipment, factors affecting employment of EVA, EVA mission integration, baselined extravehicular activity are discussed. Design requirements are also discussed.

Equine viral arteritis in breeding and sport horses in central Spain.

PubMed

Cruz-Lopez, Fatima; Newton, Richard; Sanchez-Rodriguez, Ana; Ireland, Joanne; Mughini-Gras, Lapo; Moreno, Miguel A; Fores, Paloma

2017-12-01

Equine viral arteritis (EVA) may have a high economic impact on breeding stud farms due to the occurrence of EVA-associated abortion outbreaks and the ability of the virus to persist in carrier stallions. While the consequences of EVA in premises with sport horses are usually less severe, the first confirmed outbreak of EVA in Spain occurred in a riding club in Barcelona, but no data on the seroprevalence of EVA in sport horses have been reported in Spain. Given the importance of both Spanish Purebred (SP) breeding horses and sport horses for Spain's equine industry, the aim of this study was to determine and compare the seroprevalence of EVA in these two horse populations in central Spain. Serum samples from 155 SP breeding horses residing in 16 stud farms and 105 sport horses of different breeds housed in 12 riding clubs, collected between September 2011 and November 2013, were tested using a commercial EVA antibody ELISA test with a 100% sensitivity, and confirmed by seroneutralisation (SN) test. EVA seroprevalence in SP breeding horses was higher 21.1% (95% CI 15.3-26.8%) than that in sport horses (6.7%, 95% CI 1.89-11.45%). However, the primary use (breeding vs. sport) was not significantly associated with seropositivity to Equine Arteritis Virus (EAV), suggesting that different management factors do not affect EVA circulation in these two horse populations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Risk Management in EVA

NASA Technical Reports Server (NTRS)

Hall, Jonathan; Lutomski, M.

2006-01-01

This viewgraph presentation reviews the use of risk management in Extravehicular Activities (EVA). The contents include: 1) EVA Office at NASA - JSC; 2) EVA Project Risk Management: Why and When; 3) EVA Office Risk Management: How; 4) Criteria for Closing a Risk; 5) Criteria for Accepting a Risk; 6) ISS IRMA Reference Card Data Entry Requirement s; 7) XA/ EVA Office Risk Activity Summary; 8) EVA Significant Change Summary; 9) Integrated Risk Management Application (XA) Matrix, March 31, 2004; 10) ISS Watch Item: 50XX Summary Report; and 11) EVA Project RM Usefulness

[Gender differences of psychological, nutritional, and physical fitness variables influencing obesity/overweight in Austrian children and adolescents].

PubMed

Ardelt-Gattinger, Elisabeth; Ring-Dimitriou, Susanne; Hofmann, Johannes; Paulmichl, Katharina; Zsoldos, Fanni; Weghuber, Daniel

2016-03-01

Eating behavior and physical activity behavior are under the control of certain cognitive patterns. 6600 adults and 4400 children/adolescents (8-18 years) were tested with the Obesity Diagnostics and Evaluation System (AD-EVA). Potentially significant gender differences will be detailed for the entire juvenile cohort, the subgroup of obese children/adolescents as compared to the adult cohort in this article.Among all the subscales tested, obese girls primarily showed significantly higher values of (preclinical) eating disorders than boys. These data are relevant for both prevention and health promotion.No significant differences were found in regard to sports motivation. This warrants facilitation of physical activity for both genders. Further, a male predilection for "Snacks" and "High-fat food" that could be found in the total representative study group, could not be verified in the subgroup of obese girls and boys, thus suggesting a similarily unhealthy eating behavior in both genders of juvenility.

EVA Systems Technology Gaps and Priorities 2017

NASA Technical Reports Server (NTRS)

Johnson, Brian J.; Buffington, Jesse A.

2017-01-01

Performance of Extra-Vehicular Activities (EVA) has been and will continue to be a critical capability for human space flight. Human exploration missions beyond LEO will require EVA capability for either contingency or nominal activities to support mission objectives and reduce mission risk. EVA systems encompass a wide array of products across pressure suits, life support systems, EVA tools and unique spacecraft interface hardware (i.e. EVA Translation Paths and EVA Worksites). In a fiscally limited environment with evolving transportation and habitation options, it is paramount that the EVA community's strategic planning and architecture integration products be reviewed and vetted for traceability between the mission needs far into the future to the known technology and knowledge gaps to the current investments across EVA systems. To ascertain EVA technology and knowledge gaps many things need to be brought together, assessed and analyzed. This includes an understanding of the destination environments, various mission concept of operations, current state of the art of EVA systems, EVA operational lessons learned, and reference advanced capabilities. A combined assessment of these inputs should result in well-defined list of gaps. This list can then be prioritized depending on the mission need dates and time scale of the technology or knowledge gap closure plan. This paper will summarize the current state of EVA related technology and knowledge gaps derived from NASA's Exploration EVA Reference Architecture and Operations Concept products. By linking these products and articulating NASA's approach to strategic development for EVA across all credible destinations an EVA could be done in, the identification of these gaps is then used to illustrate the tactical and strategic planning for the EVA technology development portfolio. Finally, this paper illustrates the various "touch points" with other human exploration risk identification areas including human health and performance.

Energy utilization rates during shuttle extravehicular activities.

PubMed

Waligora, J M; Kumar, K V

1995-01-01

The work rates or energy utilization rates during EVA are major factors in sizing of life support systems. These rates also provide a measure of ease of EVA and its cost in crew fatigue. From the first Shuttle EVA on the STS-6 mission in 1983, we have conducted 59 man-EVA and 341 man-hours of EVA. Energy utilization rates have been measured on each of these EVA. Metabolic rate was measured during each EVA using oxygen utilization corrected for suit leakage. From 1981-1987, these data were available for average data over the EVA or over large segments of the EVA. Since 1987, EVA oxygen utilization data were available at 2-minute intervals. The average metabolic rate on Shuttle EVA (194 kcal/hr.) has been significantly lower than metabolic rates during Apollo and Skylab missions. Peak rates have been below design levels, infrequent, and of short duration. The data suggest that the energy cost of tasks may be inversely related to the degree of training for the task. The data provide insight on the safety margins provided by life support designs and on the energy cost of Station construction EVA.

Extravehicular Activity Testing in Analog Environments: Evaluating the Effects of Center of Gravity and Environment on Human Performance

NASA Technical Reports Server (NTRS)

Chappell, Steve P.; Gernhardt, Michael L.

2009-01-01

Center of gravity (CG) is likely to be an important variable in astronaut performance during partial gravity extravehicular activity (EVA). The Apollo Lunar EVA experience revealed challenges with suit stability and control. The EVA Physiology, Systems and Performance Project (EPSP) in conjunction with the Constellation EVA Systems Project Office have developed plans to systematically understand the role of suit weight, CG and suit pressure on astronaut performance in partial gravity environments. This presentation based upon CG studies seeks to understand the impact of varied CG on human performance in lunar gravity.

EVA manipulation and assembly of space structure columns

NASA Technical Reports Server (NTRS)

Loughead, T. E.; Pruett, E. C.

1980-01-01

Assembly techniques and hardware configurations used in assembly of the basic tetrahedral cell by A7LB pressure-suited subjects in a neutral bouyancy simulator were studied. Eleven subjects participated in assembly procedures which investigated two types of structural members and two configurations of attachment hardware. The assembly was accomplished through extra-vehicular activity (EVA) only, EVA with simulated manned maneuvering unit (MMU), and EVA with simulated MMU and simulated remote manipulator system (RMS). Assembly times as low as 10.20 minutes per tetrahedron were achieved. Task element data, as well as assembly procedures, are included.

Application of Shuttle EVA Systems to Payloads. Volume 2: Payload EVA Task Completion Plans

NASA Technical Reports Server (NTRS)

1976-01-01

Candidate payload tasks for EVA application were identified and selected, based on an analysis of four representative space shuttle payloads, and typical EVA scenarios with supporting crew timelines and procedures were developed. The EVA preparations and post EVA operations, as well as the timelines emphasizing concurrent payload support functions, were also summarized.

Tracking Historical NASA EVA Training: Lifetime Surveillance of Astronaut Health (LSAH) Development of the EVA Suit Exposure Tracker (EVA SET)

NASA Technical Reports Server (NTRS)

Laughlin, Mitzi S.; Murray, Jocelyn D.; Lee, Lesley R.; Wear, Mary L.; Van Baalen, Mary

2017-01-01

During a spacewalk, designated as extravehicular activity (EVA), an astronaut ventures from the protective environment of the spacecraft into the vacuum of space. EVAs are among the most challenging tasks during a mission, as they are complex and place the astronaut in a highly stressful environment dependent on the spacesuit for survival. Due to the complexity of EVA, NASA has conducted various training programs on Earth to mimic the environment of space and to practice maneuvers in a more controlled and forgiving environment. However, rewards offset the risks of EVA, as some of the greatest accomplishments in the space program were accomplished during EVA, such as the Apollo moonwalks and the Hubble Space Telescope repair missions. Water has become the environment of choice for EVA training on Earth, using neutral buoyancy as a substitute for microgravity. During EVA training, an astronaut wears a modified version of the spacesuit adapted for working in water. This high fidelity suit allows the astronaut to move in the water while performing tasks on full-sized mockups of space vehicles, telescopes, and satellites. During the early Gemini missions, several EVA objectives were much more difficult than planned and required additional time. Later missions demonstrated that "complex (EVA) tasks were feasible when restraints maintained body position and underwater simulation training ensured a high success probability".1,2 EVA training has evolved from controlling body positioning to perform basic tasks to complex maintenance of the Hubble Space Telescope and construction of the International Space Station (ISS). Today, preparation is centered at special facilities built specifically for EVA training, such as the Neutral Buoyancy Laboratory (NBL) at NASA's Johnson Space Center ([JSC], Houston) and the Hydrolab at the Gagarin Cosmonaut Training Centre ([GCTC], Star City, outside Moscow). Underwater training for an EVA is also considered hazardous duty for NASA astronauts. This activity places astronauts at risk for decompression sickness and barotrauma as well as various musculoskeletal disorders from working in the spacesuit. The medical, operational and research communities over the years have requested access to EVA training data to better understand the risks. As a result of these requests, epidemiologists within the Lifetime Surveillance of Astronaut Health (LSAH) team have compiled records from numerous EVA training venues to quantify the exposure to EVA training. The EVA Suit Exposure Tracker (EVA SET) dataset is a compilation of ground-based training activities using the extravehicular mobility unit (EMU) in neutrally buoyant pools to enhance EVA performance on orbit. These data can be used by the current ISS program and future exploration missions by informing physicians, researchers, and operational personnel on the risks of EVA training in order that future suit and mission designs incorporate greater safety. The purpose of this technical report is to document briefly the various facilities where NASA astronauts have performed EVA training while describing in detail the EVA training records used to generate the EVA SET dataset.

A clinically authentic mouse model of enterovirus 71 (EV-A71)-induced neurogenic pulmonary oedema.

PubMed

Victorio, Carla Bianca Luena; Xu, Yishi; Ng, Qimei; Chua, Beng Hooi; Alonso, Sylvie; Chow, Vincent T K; Chua, Kaw Bing

2016-06-30

Enterovirus 71 (EV-A71) is a neurotropic virus that sporadically causes fatal neurologic illness among infected children. Animal models of EV-A71 infection exist, but they do not recapitulate in animals the spectrum of disease and pathology observed in fatal human cases. Specifically, neurogenic pulmonary oedema (NPE)-the main cause of EV-A71 infection-related mortality-is not observed in any of these models. This limits their utility in understanding viral pathogenesis of neurologic infections. We report the development of a mouse model of EV-A71 infection displaying NPE in severely affected animals. We inoculated one-week-old BALB/c mice with an adapted EV-A71 strain and identified clinical signs consistent with observations in human cases and other animal models. We also observed respiratory distress in some mice. At necropsy, we found their lungs to be heavier and incompletely collapsed compared to other mice. Serum levels of catecholamines and histopathology of lung and brain tissues of these mice strongly indicated onset of NPE. The localization of virally-induced brain lesions also suggested a potential pathogenic mechanism for EV-A71-induced NPE. This novel mouse model of virally-induced NPE represents a valuable resource for studying viral mechanisms of neuro-pathogenesis and pre-clinical testing of potential therapeutics and prophylactics against EV-A71-related neurologic complications.

Study of space shuttle EVA/IVA support requirements. Volume 1: Technical summary report

NASA Technical Reports Server (NTRS)

Copeland, R. J.; Wood, P. W., Jr.; Cox, R. L.

1973-01-01

Results are summarized which were obtained for equipment requirements for the space shuttle EVA/IVA pressure suit, life support system, mobility aids, vehicle support provisions, and energy 4 support. An initial study of tasks, guidelines, and constraints and a special task on the impact of a 10 psia orbiter cabin atmosphere are included. Supporting studies not related exclusively to any one group of equipment requirements are also summarized. Representative EVA/IVA task scenarios were defined based on an evaluation of missions and payloads. Analysis of the scenarios resulted in a total of 788 EVA/IVA's in the 1979-1990 time frame, for an average of 1.3 per shuttle flight. Duration was estimated to be under 4 hours on 98% of the EVA/IVA's, and distance from the airlock was determined to be 70 feet or less 96% of the time. Payload water vapor sensitivity was estimated to be significant on 9%-17% of the flights. Further analysis of the scenarios was carried out to determine specific equipment characteristics, such as suit cycle and mobility requirements.

Oxidative Lung Damage Resulting from Repeated Exposure to Radiation and Hyperoxia Associated with Space Exploration.

PubMed

Pietrofesa, Ralph A; Turowski, Jason B; Arguiri, Evguenia; Milovanova, Tatyana N; Solomides, Charalambos C; Thom, Stephen R; Christofidou-Solomidou, Melpo

2013-09-30

Spaceflight missions may require crewmembers to conduct Extravehicular Activities (EVA) for repair, maintenance or scientific purposes. Pre-breathe protocols in preparation for an EVA entail 100% hyperoxia exposure that may last for a few hours (5-8 hours), and may be repeated 2-3 times weekly. Each EVA is associated with additional challenges such as low levels of total body cosmic/galactic radiation exposure that may present a threat to crewmember health and therefore, pose a threat to the success of the mission. We have developed a murine model of combined, hyperoxia and radiation exposure (double-hit) in the context of evaluating countermeasures to oxidative lung damage associated with space flight. In the current study, our objective was to characterize the early and chronic effects of repeated single and double-hit challenge on lung tissue using a novel murine model of repeated exposure to low-level total body radiation and hyperoxia. This is the first study of its kind evaluating lung damage relevant to space exploration in a rodent model. Mouse cohorts (n=5-15/group) were exposed to repeated: a) normoxia; b) >95% O 2 (O 2 ); c) 0.25Gy single fraction gamma radiation (IR); or d) a combination of O 2 and IR (O 2 +IR) given 3 times per week for 4 weeks. Lungs were evaluated for oxidative damage, active TGFβ1 levels, cell apoptosis, inflammation, injury, and fibrosis at 1, 2, 4, 8, 12, 16, and 20 weeks post-initiation of exposure. Mouse cohorts exposed to all challenge conditions displayed decreased bodyweight compared to untreated controls at 4 and 8 weeks post-challenge initiation. Chronic oxidative lung damage to lipids (malondialdehyde levels), DNA (TUNEL, cleaved Caspase 3, cleaved PARP positivity) leading to apoptotic cell death and to proteins (nitrotyrosine levels) was elevated all treatment groups. Importantly, significant systemic oxidative stress was also noted at the late phase in mouse plasma, BAL fluid, and urine. Importantly, however, late oxidative damage across all parameters that we measured was significantly higher than controls in all cohorts but was exacerbated by the combined exposure to O 2 and IR. Additionally, impaired levels of arterial blood oxygenation were noted in all exposure cohorts. Significant but transient elevation of lung tissue fibrosis ( p <0.05), determined by lung hydroxyproline content, was detected as early as 2 week in mice exposed to challenge conditions and persisted for 4-8 weeks only. Interestingly, active TGFβ1 levels in +BAL fluid was also transiently elevated during the exposure time only (1-4 weeks). Inflammation and lung edema/lung injury was also significantly elevated in all groups at both early and late time points, especially the double-hit group. We have characterized significant, early and chronic lung changes consistent with oxidative tissue damage in our murine model of repeated radiation and hyperoxia exposure relevant to space travel. Lung tissue changes, detectable several months after the original exposure, include significant oxidative lung damage (lipid peroxidation, DNA damage and protein nitrosative stress) and increased pulmonary fibrosis. These findings, along with increased oxidative stress in diverse body fluids and the observed decreases in blood oxygenation levels in all challenge conditions (whether single or in combination), lead us to conclude that in our model of repeated exposure to oxidative stressors, chronic tissue changes are detected that persist even months after the exposure to the stressor has ended. This data will provide useful information in the design of countermeasures to tissue oxidative damage associated with space exploration.

Oxidative Lung Damage Resulting from Repeated Exposure to Radiation and Hyperoxia Associated with Space Exploration

PubMed Central

Pietrofesa, Ralph A; Turowski, Jason B; Arguiri, Evguenia; Milovanova, Tatyana N; Solomides, Charalambos C; Thom, Stephen R; Christofidou-Solomidou, Melpo

2013-01-01

Background Spaceflight missions may require crewmembers to conduct Extravehicular Activities (EVA) for repair, maintenance or scientific purposes. Pre-breathe protocols in preparation for an EVA entail 100% hyperoxia exposure that may last for a few hours (5-8 hours), and may be repeated 2-3 times weekly. Each EVA is associated with additional challenges such as low levels of total body cosmic/galactic radiation exposure that may present a threat to crewmember health and therefore, pose a threat to the success of the mission. We have developed a murine model of combined, hyperoxia and radiation exposure (double-hit) in the context of evaluating countermeasures to oxidative lung damage associated with space flight. In the current study, our objective was to characterize the early and chronic effects of repeated single and double-hit challenge on lung tissue using a novel murine model of repeated exposure to low-level total body radiation and hyperoxia. This is the first study of its kind evaluating lung damage relevant to space exploration in a rodent model. Methods Mouse cohorts (n=5-15/group) were exposed to repeated: a) normoxia; b) >95% O2 (O2); c) 0.25Gy single fraction gamma radiation (IR); or d) a combination of O2 and IR (O2+IR) given 3 times per week for 4 weeks. Lungs were evaluated for oxidative damage, active TGFβ1 levels, cell apoptosis, inflammation, injury, and fibrosis at 1, 2, 4, 8, 12, 16, and 20 weeks post-initiation of exposure. Results Mouse cohorts exposed to all challenge conditions displayed decreased bodyweight compared to untreated controls at 4 and 8 weeks post-challenge initiation. Chronic oxidative lung damage to lipids (malondialdehyde levels), DNA (TUNEL, cleaved Caspase 3, cleaved PARP positivity) leading to apoptotic cell death and to proteins (nitrotyrosine levels) was elevated all treatment groups. Importantly, significant systemic oxidative stress was also noted at the late phase in mouse plasma, BAL fluid, and urine. Importantly, however, late oxidative damage across all parameters that we measured was significantly higher than controls in all cohorts but was exacerbated by the combined exposure to O2 and IR. Additionally, impaired levels of arterial blood oxygenation were noted in all exposure cohorts. Significant but transient elevation of lung tissue fibrosis (p<0.05), determined by lung hydroxyproline content, was detected as early as 2 week in mice exposed to challenge conditions and persisted for 4-8 weeks only. Interestingly, active TGFβ1 levels in +BAL fluid was also transiently elevated during the exposure time only (1-4 weeks). Inflammation and lung edema/lung injury was also significantly elevated in all groups at both early and late time points, especially the double-hit group. Conclusion We have characterized significant, early and chronic lung changes consistent with oxidative tissue damage in our murine model of repeated radiation and hyperoxia exposure relevant to space travel. Lung tissue changes, detectable several months after the original exposure, include significant oxidative lung damage (lipid peroxidation, DNA damage and protein nitrosative stress) and increased pulmonary fibrosis. These findings, along with increased oxidative stress in diverse body fluids and the observed decreases in blood oxygenation levels in all challenge conditions (whether single or in combination), lead us to conclude that in our model of repeated exposure to oxidative stressors, chronic tissue changes are detected that persist even months after the exposure to the stressor has ended. This data will provide useful information in the design of countermeasures to tissue oxidative damage associated with space exploration. PMID:24358450

Knockout of Eva1a leads to rapid development of heart failure by impairing autophagy

PubMed Central

Zhang, Shu; Lin, Xin; Li, Ge; Shen, Xue; Niu, Di; Lu, Guang; Fu, Xin; Chen, Yingyu; Cui, Ming; Bai, Yun

2017-01-01

EVA1A (Eva-1 homologue A) is a novel lysosome and endoplasmic reticulum-associated protein that can regulate cell autophagy and apoptosis. Eva1a is expressed in the myocardium, but its function in myocytes has not yet been investigated. Therefore, we generated inducible, cardiomyocyte-specific Eva1a knockout mice with an aim to determine the role of Eva1a in cardiac remodelling in the adult heart. Data from experiments showed that loss of Eva1a in the adult heart increased cardiac fibrosis, promoted cardiac hypertrophy, and led to cardiomyopathy and death. Further investigation suggested that this effect was associated with impaired autophagy and increased apoptosis in Eva1a knockout hearts. Moreover, knockout of Eva1a activated Mtor signalling and the subsequent inhibition of autophagy. In addition, Eva1a knockout hearts showed disorganized sarcomere structure and mitochondrial misalignment and aggregation, leading to the lack of ATP generation. Collectively, these data demonstrated that Eva1a improves cardiac function and inhibits cardiac hypertrophy and fibrosis by increasing autophagy. In conclusion, our results demonstrated that Eva1a may have an important role in maintaining cardiac homeostasis. PMID:28151473

Post-Shuttle EVA Operations on ISS

NASA Technical Reports Server (NTRS)

West, William; Witt, Vincent; Chullen, Cinda

2010-01-01

The expected retirement of the NASA Space Transportation System (also known as the Space Shuttle ) by 2011 will pose a significant challenge to Extra-Vehicular Activities (EVA) on-board the International Space Station (ISS). The EVA hardware currently used to assemble and maintain the ISS was designed assuming that it would be returned to Earth on the Space Shuttle for refurbishment, or if necessary for failure investigation. With the retirement of the Space Shuttle, a new concept of operations was developed to enable EVA hardware (Extra-vehicular Mobility Unit (EMU), Airlock Systems, EVA tools, and associated support hardware and consumables) to perform ISS EVAs until 2015, and possibly beyond to 2020. Shortly after the decision to retire the Space Shuttle was announced, the EVA 2010 Project was jointly initiated by NASA and the One EVA contractor team. The challenges addressed were to extend the operating life and certification of EVA hardware, to secure the capability to launch EVA hardware safely on alternate launch vehicles, to protect for EMU hardware operability on-orbit, and to determine the source of high water purity to support recharge of PLSSs (no longer available via Shuttle). EVA 2010 Project includes the following tasks: the development of a launch fixture that would allow the EMU Portable Life Support System (PLSS) to be launched on-board alternate vehicles; extension of the EMU hardware maintenance interval from 3 years (current certification) to a minimum of 6 years (to extend to 2015); testing of recycled ISS Water Processor Assembly (WPA) water for use in the EMU cooling system in lieu of water resupplied by International Partner (IP) vehicles; development of techniques to remove & replace critical components in the PLSS on-orbit (not routine); extension of on-orbit certification of EVA tools; and development of an EVA hardware logistical plan to support the ISS without the Space Shuttle. Assumptions for the EVA 2010 Project included no more than 8 EVAs per year for ISS EVA operations in the Post-Shuttle environment and limited availability of cargo upmass on IP launch vehicles. From 2010 forward, EVA operations on-board the ISS without the Space Shuttle will be a paradigm shift in safely operating EVA hardware on orbit and the EVA 2010 effort was initiated to accommodate this significant change in EVA evolutionary history. 1

Post-Shuttle EVA Operations on ISS

NASA Technical Reports Server (NTRS)

West, Bill; Witt, Vincent; Chullen, Cinda

2010-01-01

The EVA hardware used to assemble and maintain the ISS was designed with the assumption that it would be returned to Earth on the Space Shuttle for ground processing, refurbishment, or failure investigation (if necessary). With the retirement of the Space Shuttle, a new concept of operations was developed to enable EVA hardware (EMU, Airlock Systems, EVA tools, and associated support equipment and consumables) to perform ISS EVAs until 2016 and possibly beyond to 2020. Shortly after the decision to retire the Space Shuttle was announced, NASA and the One EVA contractor team jointly initiated the EVA 2010 Project. Challenges were addressed to extend the operating life and certification of EVA hardware, secure the capability to launch EVA hardware safely on alternate launch vehicles, and protect EMU hardware operability on orbit for long durations.

Diagnostic Value of SLC26A4 Mutation Status in Hereditary Hearing Loss With EVA: A PRISMA-Compliant Meta-Analysis.

PubMed

Lu, Ya-Jie; Yao, Jun; Wei, Qin-Jun; Xing, Guang-Qian; Cao, Xin

2015-12-01

Many SLC26A4 mutations have been identified in patients with nonsyndromic enlarged vestibular aqueduct (EVA). However, the roles of SLC26A4 genotypes and phenotypes in hereditary deafness remain unexplained. This study aims to perform a meta-analysis based on the PRISMA statement to evaluate the diagnostic value of SLC26A4 mutant alleles and their correlations with multiethnic hearing phenotypes in EVA patients. The systematic literature search of the PubMed, Wiley Online Library, EMBASE, Web of Science, and Science Direct databases was conducted in English for articles published before July 15, 2015. Two investigators independently reviewed retrieved literature and evaluated eligibility. Discrepancy was resolved by discussion and a third investigator. Quality of included studies was evaluated using Newcastle-Ottawa Quality Assessment Scale. Data were synthesized using random-effect or fixed-effect models. The effect sizes were estimated by measuring odds ratios (ORs) with 95% confidence interval (CI). Twenty-five eligible studies involved 2294 cases with EVA data. A total of 272 SLC26A4 variations were found in deafness with EVA and 26 mutations of SCL26A4 had higher frequency. The overall OR was 646.71 (95% CI: 383.30-1091.15, P = 0.000). A total of 22 mutants were considered statistically significant in all ethnicities (ORs >1, P < 0.05). In particular, 8 mutants were specificity of EVA phenotypes in mutations of SLC26A4 for Asia deafness populations (ORs >1, P < 0.05), 4 mutants for Europe and North America (ORs >1, P < 0.05), and the IVS7-2A>G mutations in SLC26A4 were found to have the highest frequency in deafness individuals with EVA phenotype (62.42%). Moreover, subgroups for studies limited to cases with EVA phenotype, 11 mutants relevant risks (RRs) were P < 0.05, especially for IVS7-2A>G bi-allelic mutants assayed in a deafness population (RR = 0.880, P = 0.000). Diagnostic accuracy of SLC26A4 mutation results also identified the significant association of IVS7-2A>G (AUC = 0.99, 95% CI: 0.97-0.99) and p.H723R (AUC = 0.99, 95% CI: 0.98-1.00) detecting deafness with EVA. To conclude, the IVS7-2A>G and H723R in SLC26A4 present a significant predicting value and discriminatory ability for clinical use on diagnosis of EVA within a deafness population.

[Analysis of decompression safety during extravehicular activity of astronauts in the light of probability theory].

PubMed

Nikolaev, V P; Katuntsev, V P

1998-01-01

Objectives of the study were comparative assessment of the risk of decompression sickness (DCS) in human subjects during shirt-sleeve simulation of extravehicular activity (EVA) following Russian and U.S. protocols, and analysis of causes of the difference between real and simulated EVA decompression safety. To this end, DCS risk during exposure to a sing-step decompression was estimated with an original method. According to the method, DCS incidence is determined by distribution of nucleation efficacy index (z) in the worst body tissues and its critical values (zm) as a function of initial nitrogen tension in these tissues and final ambient pressure post decompression. Gaussian distribution of z values was calculated basing on results of the DCS risk evaluation on the U.S. EVA protocol in an unsuited chamber test with various pre-breath procedures (Conkin et al., 1987). Half-time of nitrogen washout from the worst tissues was presumed to be 480 min. Calculated DCS risk during short-sleeve EVA simulation by the Russian and U.S. protocols with identical physical loading made up 19.2% and 23.4%, respectively. Effects of the working spacesuit pressure, spacesuit rigidity, metabolic rates during operations in EVA space suit, transcutaneous nitrogen exchange in the oxygen atmosphere of space suit, microgravity, analgesics, short compression due to spacesuit leak tests on the eye of EVA are discussed. Data of the study illustrate and advocate for high decompression safety of current Russian and U.S. EVA protocols.

Lunar Extravehicular Activity Program

NASA Technical Reports Server (NTRS)

Heartsill, Amy Ellison

2006-01-01

Extravehicular Activity (EVA) has proven an invaluable tool for space exploration since the inception of the space program. There are situations in which the best means to evaluate, observe, explore and potentially troubleshoot space systems are accomplished by direct human intervention. EVA provides this unique capability. There are many aspects of the technology required to enable a "miniature spaceship" to support individuals in a hostile environment in order to accomplish these tasks. This includes not only the space suit assembly itself, but the tools, design interfaces of equipment on which EVA must work and the specific vehicles required to support transfer of humans between habitation areas and the external world. This lunar mission program will require EVA support in three primary areas. The first of these areas include Orbital stage EVA or micro-gravity EVA which includes both Low Earth Orbit (LEO), transfer and Lunar Orbit EVA. The second area is Lunar Lander EVA capability, which is lunar surface EVA and carries slightly different requirements from micro-gravity EVA. The third and final area is Lunar Habitat based surface EVA, which is the final system supporting a long-term presence on the moon.

EVA Wiki - Transforming Knowledge Management for EVA Flight Controllers and Instructors

NASA Technical Reports Server (NTRS)

Johnston, Stephanie S.; Alpert, Brian K.; Montalvo, Edwin James; Welsh, Lawrence Daren; Wray, Scott; Mavridis, Costa

2016-01-01

The EVA Wiki was recently implemented as the primary knowledge database to retain critical knowledge and skills in the EVA Operations group at NASA's Johnson Space Center by ensuring that information is recorded in a common, easy to search repository. Prior to the EVA Wiki, information required for EVA flight controllers and instructors was scattered across different sources, including multiple file share directories, SharePoint, individual computers, and paper archives. Many documents were outdated, and data was often difficult to find and distribute. In 2011, a team recognized that these knowledge management problems could be solved by creating an EVA Wiki using MediaWiki, a free and open-source software developed by the Wikimedia Foundation. The EVA Wiki developed into an EVA-specific Wikipedia on an internal NASA server. While the technical implementation of the wiki had many challenges, one of the biggest hurdles came from a cultural shift. Like many enterprise organizations, the EVA Operations group was accustomed to hierarchical data structures and individually-owned documents. Instead of sorting files into various folders, the wiki searches content. Rather than having a single document owner, the wiki harmonized the efforts of many contributors and established an automated revision controlled system. As the group adapted to the wiki, the usefulness of this single portal for information became apparent. It transformed into a useful data mining tool for EVA flight controllers and instructors, as well as hundreds of others that support the EVA. Program managers, engineers, astronauts, flight directors, and flight controllers in differing disciplines now have an easier-to-use, searchable system to find EVA data. This paper presents the benefits the EVA Wiki has brought to NASA's EVA community, as well as the cultural challenges it had to overcome.

EVA Wiki - Transforming Knowledge Management for EVA Flight Controllers and Instructors

NASA Technical Reports Server (NTRS)

Johnston, Stephanie S.; Alpert, Brian K.; Montalvo, Edwin James; Welsh, Lawrence Daren; Wray, Scott; Mavridis, Costa

2016-01-01

The EVA Wiki was recently implemented as the primary knowledge database to retain critical knowledge and skills in the EVA Operations group at NASA's Johnson Space Center by ensuring that information is recorded in a common, easy to search repository. Prior to the EVA Wiki, information required for EVA flight controllers and instructors was scattered across different sources, including multiple file share directories, SharePoint, individual computers, and paper archives. Many documents were outdated, and data was often difficult to find and distribute. In 2011, a team recognized that these knowledge management problems could be solved by creating an EVA Wiki using MediaWiki, a free and open-source software developed by the Wikimedia Foundation. The EVA Wiki developed into an EVA-specific Wikipedia on an internal NASA server. While the technical implementation of the wiki had many challenges, one of the biggest hurdles came from a cultural shift. Like many enterprise organizations, the EVA Operations group was accustomed to hierarchical data structures and individually-owned documents. Instead of sorting files into various folders, the wiki searches content. Rather than having a single document owner, the wiki harmonized the efforts of many contributors and established an automated revision controlled system. As the group adapted to the wiki, the usefulness of this single portal for information became apparent. It transformed into a useful data mining tool for EVA flight controllers and instructors, as well as hundreds of others that support EVA. Program managers, engineers, astronauts, flight directors, and flight controllers in differing disciplines now have an easier-to-use, searchable system to find EVA data. This paper presents the benefits the EVA Wiki has brought to NASA's EVA community, as well as the cultural challenges it had to overcome.

Development of new EVA formulations for improved performance at NREL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.

1997-02-01

We review in chronological order the research stages and fundamental concepts involved in developing modified and new EVA formulations for improved performance against photo-induced degradation and discoloration. The new NREL EVA formulations use additives totally different from the present commercial formulations (EVA A9918 and EVA 15295). Validation of their long-term photostability and thermostability is presently under way. Together with UV-absorbing glass superstrates, they may offer better success in achieving a more reliable module performance and longer service life without significant EVA discoloration problems, which are commonly experienced with EVA A9918 and, at a lesser rate, EVA 15295. {copyright} {ital 1997more » American Institute of Physics.}« less

Effect of EVA on thermal stability, flammability, mechanical properties of HDPE/EVA/Mg(OH)2 composites

NASA Astrophysics Data System (ADS)

Cao, R.; Deng, Z. L.; Ma, Y. H.; Chen, X. L.

2017-06-01

In this work, ethylene vinyl acetate (EVA) is introduced to improve the properties of high-density polyethylene (HDPE)/magnesium hydroxide (MH) composites. The thermal stability, flame retardancy and mechanical properties of HDPE/EVA/MH composites are investigated and discussed. With increasing content of EVA, the limiting oxygen index (LOI) of the composites increases. The thermal stability analysis shows that the initial decomposition temperature begins at a low temperature; however, the residues of the composites at 600°C increase when HDPE is replaced by small amounts of EVA. The early degradation absorbs heat, dilute oxygen and residue. During this process, it protects the matrix inside. Compared with the HDPE/MH and EVA/MH composites, the ternary HDPE/EVA/MH composites exhibit better flame retardancy by increasing the LOI values, and reducing the heat release rate (HRR) and total heat release (THR). With increasing content of EVA, the mechanical properties can also be improved, which is attributed to the good affinity between EVA and MH particles.

Application of shuttle EVA systems to payloads. Volume 1: EVA systems and operational modes description

NASA Technical Reports Server (NTRS)

1976-01-01

Descriptions of the EVA system baselined for the space shuttle program were provided, as well as a compendium of data on available EVA operational modes for payload and orbiter servicing. Operational concepts and techniques to accomplish representative EVA payload tasks are proposed. Some of the subjects discussed include: extravehicular mobility unit, remote manipulator system, airlock, EVA translation aids, restraints, workstations, tools and support equipment.

Spacesuit Glove-Induced Hand Trauma and Analysis of Potentially Related Risk Variables

NASA Technical Reports Server (NTRS)

Charvat, Chacqueline M.; Norcross, Jason; Reid, Christopher R.; McFarland, Shane M.

2015-01-01

Injuries to the hands are common among astronauts who train for extravehicular activity (EVA). When the gloves are pressurized, they restrict movement and create pressure points during tasks, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally more severe injuries such as onycholysis. Glove injuries, both anecdotal and recorded, have been reported during EVA training and flight persistently through NASA's history regardless of mission or glove model. Theories as to causation such as glove-hand fit are common but often lacking in supporting evidence. Previous statistical analysis has evaluated onycholysis in the context of crew anthropometry only. The purpose of this study was to analyze all injuries (as documented in the medical records) and available risk factor variables with the goal to determine engineering and operational controls that may reduce hand injuries due to the EVA glove in the future. A literature review and data mining study were conducted between 2012 and 2014. This study included 179 US NASA crew who trained or completed an EVA between 1981 and 2010 (crossing both Shuttle and ISS eras) and wore either the 4000 Series or Phase VI glove during Extravehicular Mobility Unit (EMU) spacesuit EVA training and flight. All injuries recorded in medical records were analyzed in their association to candidate risk factor variables. Those risk factor variables included demographic characteristics, hand anthropometry, glove fit characteristics, and training/EVA characteristics. Utilizing literature, medical records and anecdotal causation comments recorded in crewmember injury data, investigators were able to identify several risk factors associated with increased risk of glove related injuries. Prime among them were smaller hand anthropometry, duration of individual suited exposures, and improper glove-hand fit as calculated by the difference in the anthropometry middle finger length compared to the baseline EVA glove middle finger length.

Spacesuit Glove-Induced Hand Trauma and Analysis of Potentially Related Risk Variables

NASA Technical Reports Server (NTRS)

McFarland, Shane M.; Reid, Christopher R.; Norcross, Jason; Charvat, Jacqueline M.

2015-01-01

Injuries to the hands are common among astronauts who train for extravehicular activity (EVA). When the gloves are pressurized, they restrict movement and create pressure points during tasks, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally more severe injuries such as onycholysis. Glove injuries, both anecdotal and recorded, have been reported during EVA training and flight persistently through NASA's history regardless of mission or glove model. Theories as to causation such as glove-hand fit are common but often lacking in supporting evidence. Previous statistical analysis has evaluated onycholysis in the context of crew anthropometry only (Opperman et al 2010). The purpose of this study was to analyze all injuries (as documented in the medical records) and available risk factor variables with the goal to determine engineering and operational controls that may reduce hand injuries due to the EVA glove in the future. A literature review and data mining study were conducted between 2012 and 2014. This study included 179 US NASA crew who trained or completed an EVA between 1981 and 2010 (crossing both Shuttle and ISS eras) and wore either the 4000 Series or Phase VI glove during Extravehicular Mobility Unit (EMU) spacesuit EVA training and flight. All injuries recorded in medical records were analyzed in their association to candidate risk factor variables. Those risk factor variables included demographic characteristics, hand anthropometry, glove fit characteristics, and training/EVA characteristics. Utilizing literature, medical records and anecdotal causation comments recorded in crewmember injury data, investigators were able to identify several risk factors associated with increased risk of glove related injuries. Prime among them were smaller hand anthropometry, duration of individual suited exposures, and improper glove-hand fit as calculated by the difference in the anthropometry middle finger length compared to the baseline EVA glove middle finger length.

Preparation, Characterization and Thermo-Chromic Properties of EVA/VO2 Laminate Films for Smart Window Applications and Energy Efficiency in Building

PubMed Central

Srirodpai, Onruthai; Wootthikanokkhan, Jatuphorn; Nawalertpanya, Saiwan; Yuwawech, Kitti; Meeyoo, Vissanu

2017-01-01

Thermochromic films based on vanadium dioxide (VO2)/ethylene vinyl acetate copolymer (EVA) composite were developed. The monoclinic VO2 particles was firstly prepared via hydrothermal and calcination processes. The effects of hydrothermal time and tungsten doping agent on crystal structure and morphology of the calcined metal oxides were reported. After that, 1 wt % of the prepared VO2 powder was mixed with EVA compound, using two different mixing processes. It was found that mechanical properties of the EVA/VO2 films prepared by the melt process were superior to those of which prepared by the solution process. On the other hand, percentage visible light transmittance of the solution casted EVA/VO2 film was greater than that of the melt processed composite film. This was related to the different gel content of EVA rubber and state of dispersion and distribution of VO2 within the polymer matrix phase. Thermochromic behaviors and heat reflectance of the EVA/VO2 film were also verified. In overall, this study demonstrated that it was possible to develop a thermochromic film using the polymer composite approach. In this regard, the mixing condition was found to be one of the most important factors affecting morphology and thermo-mechanical properties of the films. PMID:28772413

Preparation, Characterization and Thermo-Chromic Properties of EVA/VO₂ Laminate Films for Smart Window Applications and Energy Efficiency in Building.

PubMed

Srirodpai, Onruthai; Wootthikanokkhan, Jatuphorn; Nawalertpanya, Saiwan; Yuwawech, Kitti; Meeyoo, Vissanu

2017-01-11

Thermochromic films based on vanadium dioxide (VO₂)/ethylene vinyl acetate copolymer (EVA) composite were developed. The monoclinic VO₂ particles was firstly prepared via hydrothermal and calcination processes. The effects of hydrothermal time and tungsten doping agent on crystal structure and morphology of the calcined metal oxides were reported. After that, 1 wt % of the prepared VO₂ powder was mixed with EVA compound, using two different mixing processes. It was found that mechanical properties of the EVA/VO₂ films prepared by the melt process were superior to those of which prepared by the solution process. On the other hand, percentage visible light transmittance of the solution casted EVA/VO₂ film was greater than that of the melt processed composite film. This was related to the different gel content of EVA rubber and state of dispersion and distribution of VO₂ within the polymer matrix phase. Thermochromic behaviors and heat reflectance of the EVA/VO₂ film were also verified. In overall, this study demonstrated that it was possible to develop a thermochromic film using the polymer composite approach. In this regard, the mixing condition was found to be one of the most important factors affecting morphology and thermo-mechanical properties of the films.

Enhancing enterovirus A71 vaccine production yield by microcarrier profusion bioreactor culture.

PubMed

Liu, Chia-Chyi; Wu, Suh-Chin; Wu, Shang-Rung; Lin, Hsiao-Yu; Guo, Meng-Shin; Yung-Chih Hu, Alan; Chow, Yen-Hung; Chiang, Jen-Ron; Shieh, Dar-Bin; Chong, Pele

2018-05-24

Hand, foot and mouth diseases (HFMD) are mainly caused by Enterovirus A71 (EV-A71) infections. Clinical trials in Asia conducted with formalin-inactivated EV-A71 vaccine candidates produced from serum-free Vero cell culture using either roller bottle or cell factory technology, are found to be safe and highly efficacious. To increase vaccine yields and reduce the production costs, the bioprocess improvement for EV-A71 vaccine manufacturing is currently being investigated. The parameters that could affect and enhance the production yields of EV-A71 virus growth in the microcarrier bioreactor were investigated. The medium replacement culture strategy included a multi-harvested semi-batch process and perfusion technology and was found to increase the production yields more than 7-14 folds. Based on the western blot and cryo-EM analyses of the EV-A71 virus particles produced from either the multi-harvested semi-batch (MHSBC) or perfusion cultures were found to be similar to those virus particles obtained from the single batch culture. Mouse immunogenicity studies indicate that the EV-A71 vaccine candidates produced from the perfusion culture have similar potency to those obtained from single batch bioprocess. The physical structures of the EV-A71 particles revealed by the cryo-EM analysis were found to be spherical capsid particles. These results provide feasible technical bioprocesses for increasing virus yields and the scale up of EV-A71 vaccine manufacturing using the bioreactor cell culture methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

Risk Factors for Enterovirus A71 Seropositivity in Rural Indigenous Populations in West Malaysia.

PubMed

NikNadia, Nmn; Sam, I-Ching; Khaidir, Nasibah; Ngui, Romano; Lim, Yvonne A L; Goh, Xiang Ting; Choy, Seow Huey; Chan, Yoke Fun

2016-01-01

Enterovirus A71 (EV-A71), which is transmitted by the fecal-oral route, causes hand, foot and mouth disease and, rarely, severe neurological complications. In Malaysia, the indigenous rural community (Orang Asli) has a high prevalence of parasitic diseases due to poor sanitation, water supply and hygiene practices. This cross-sectional study compared the seroepidemiology of EV-A71 among rural Orang Asli and urban Kuala Lumpur populations in West Malaysia, and determined the risk factors associated with EV-A71 seropositivity in rural Orang Asli. Seropositive rates were determined by neutralization assay. EV-A71 seropositivity was strongly associated with increasing age in both populations. Rural Orang Asli children ≤12 years had significantly higher EV-A71 seropositivity rates than urban Kuala Lumpur children (95.5% vs 57.6%, P < 0.001), and also higher rates in the age groups of 1-3, 4-6 and 7-12 years. Multivariate analysis confirmed that age ≤12 years (adjusted OR 8.1, 95% CI 3.2-20.7, P < 0.001) and using untreated water (adjusted OR 6.2, 95% CI 2.3-16.6, P < 0.001) were independently associated with EV-A71 seropositivity in the Orang Asli population. Supply of clean drinking water may reduce the risk of EV-A71 infection. With significantly higher EV-A71 seropositive rates, younger rural children should be a priority target for future vaccination programs in Malaysia.

Human Enterovirus 71 Protein Displayed on the Surface of Saccharomyces cerevisiae as an Oral Vaccine.

PubMed

Zhang, Congdang; Wang, Yi; Ma, Shuzhi; Li, Leike; Chen, Liyun; Yan, Huimin; Peng, Tao

2016-06-01

Human enterovirus 71 (EV-A71), a major agent of hand, foot, and mouth disease, has become an important public health issue in recent years. No effective antiviral or vaccines against EV-A71 infection are currently available. EV-A71 infection intrudes bodies through the gastric mucosal surface and it is necessary to enhance mucosal immune response to protect children from these pathogens. Recently, the majority of EV-A71 vaccine candidates have been developed for parenteral immunization. However, parenteral vaccine candidates often induce poor mucosal responses. On the other hand, oral vaccines could induce effective mucosal and systemic immunity, and could be easily and safely administered. Thus, proper oral vaccines have attached more interest compared with parenteral vaccine. In this study, the major immunogenic capsid protein of EV-A71 was displayed on the surface of Saccharomyces cerevisiae. Oral immunization of mice with surface-displayed VP1 S. cerevisiae induced systemic humoral and mucosal immune responses, including virus-neutralizing titers, VP1-specific antibody, and the induction of Th1 immune responses in the spleen. Furthermore, oral immunization of mother mice with surface-displayed VP1 S. cerevisiae conferred protection to neonatal mice against the lethal EV-A71 infection. Furthermore, we observed that multiple boost immunization as well as higher immunization dosage could induce higher EV-A71-specific immune response. Our results demonstrated that surface-displayed VP1 S. cerevisiae could be used as potential oral vaccine against EV-A71 infection.

Risk Factors for Enterovirus A71 Seropositivity in Rural Indigenous Populations in West Malaysia

PubMed Central

NikNadia, NMN; Sam, I-Ching; Khaidir, Nasibah; Ngui, Romano; Lim, Yvonne A. L.; Goh, Xiang Ting; Choy, Seow Huey; Chan, Yoke Fun

2016-01-01

Enterovirus A71 (EV-A71), which is transmitted by the fecal-oral route, causes hand, foot and mouth disease and, rarely, severe neurological complications. In Malaysia, the indigenous rural community (Orang Asli) has a high prevalence of parasitic diseases due to poor sanitation, water supply and hygiene practices. This cross-sectional study compared the seroepidemiology of EV-A71 among rural Orang Asli and urban Kuala Lumpur populations in West Malaysia, and determined the risk factors associated with EV-A71 seropositivity in rural Orang Asli. Seropositive rates were determined by neutralization assay. EV-A71 seropositivity was strongly associated with increasing age in both populations. Rural Orang Asli children ≤12 years had significantly higher EV-A71 seropositivity rates than urban Kuala Lumpur children (95.5% vs 57.6%, P < 0.001), and also higher rates in the age groups of 1–3, 4–6 and 7–12 years. Multivariate analysis confirmed that age ≤12 years (adjusted OR 8.1, 95% CI 3.2–20.7, P < 0.001) and using untreated water (adjusted OR 6.2, 95% CI 2.3–16.6, P < 0.001) were independently associated with EV-A71 seropositivity in the Orang Asli population. Supply of clean drinking water may reduce the risk of EV-A71 infection. With significantly higher EV-A71 seropositive rates, younger rural children should be a priority target for future vaccination programs in Malaysia. PMID:26866912

Wax inhibitor based on ethylene vinyl acetate with methyl methacrylate and diethanolamine for crude oil pipeline

NASA Astrophysics Data System (ADS)

Anisuzzaman, S. M.; Abang, S.; Bono, A.; Krishnaiah, D.; Karali, R.; Safuan, M. K.

2017-06-01

Wax precipitation and deposition is one of the most significant flow assurance challenges in the production system of the crude oil. Wax inhibitors are developed as a preventive strategy to avoid an absolute wax deposition. Wax inhibitors are polymers which can be known as pour point depressants as they impede the wax crystals formation, growth, and deposition. In this study three formulations of wax inhibitors were prepared, ethylene vinyl acetate, ethylene vinyl acetate co-methyl methacrylate (EVA co-MMA) and ethylene vinyl acetate co-diethanolamine (EVA co-DEA) and the comparison of their efficiencies in terms of cloud point¸ pour point, performance inhibition efficiency (%PIE) and viscosity were evaluated. The cloud point and pour point for both EVA and EVA co-MMA were similar, 15°C and 10-5°C, respectively. Whereas, the cloud point and pour point for EVA co-DEA were better, 10°C and 10-5°C respectively. In conclusion, EVA co-DEA had shown the best % PIE (28.42%) which indicates highest percentage reduction of wax deposit as compared to the other two inhibitors.

Mapping Enterovirus A71 Antigenic Determinants from Viral Evolution.

PubMed

Huang, Sheng-Wen; Tai, Ching-Hui; Fonville, Judith M; Lin, Chin-Hui; Wang, Shih-Min; Liu, Ching-Chung; Su, Ih-Jen; Smith, Derek J; Wang, Jen-Ren

2015-11-01

Human enterovirus A71 (EV-A71) belongs to the Enterovirus A species in the Picornaviridae family. Several vaccines against EV-A71, a disease causing severe neurological complications or even death, are currently under development and being tested in clinical trials, and preventative vaccination programs are expected to start soon. To characterize the potential for antigenic change of EV-A71, we compared the sequences of two antigenically diverse genotype B4 and B5 strains of EV-A71 and identified substitutions at residues 98, 145, and 164 in the VP1 capsid protein as antigenic determinants. To examine the effects of these three substitutions on antigenicity, we constructed a series of recombinant viruses containing different mutation combinations at these three residues with a reverse genetics system and then investigated the molecular basis of antigenic changes with antigenic cartography. We found that a novel EV-A71 mutant, containing lysine, glutamine, and glutamic acid at the respective residues 98, 145, and 164 in the VP1 capsid protein, exhibited neutralization reduction against patients' antisera and substantially increased virus binding ability to human cells. These observations indicated that this low-neutralization-reactive EV-A71 VP1-98K/145Q/164E mutant potentially increases viral binding ability and that surveillance studies should look out for these mutants, which could compromise vaccine efficacy. Emerging and reemerging EV-A71 viruses can cause severe neurological etiology, primarily affecting children, especially around Asia-Pacific countries. We identified a set of mutations in EV-A71 that both reduced neutralization activity against humoral immunity in antisera of patients and healthy adults and greatly increased the viral binding ability to cells. These findings provide important insights for EV-A71 antigenic determinants and emphasize the importance of continuous surveillance, especially after EV-A71 vaccination programs begin. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Mapping Enterovirus A71 Antigenic Determinants from Viral Evolution

PubMed Central

Huang, Sheng-Wen; Tai, Ching-Hui; Fonville, Judith M.; Lin, Chin-Hui; Wang, Shih-Min; Liu, Ching-Chung; Su, Ih-Jen

2015-01-01

ABSTRACT Human enterovirus A71 (EV-A71) belongs to the Enterovirus A species in the Picornaviridae family. Several vaccines against EV-A71, a disease causing severe neurological complications or even death, are currently under development and being tested in clinical trials, and preventative vaccination programs are expected to start soon. To characterize the potential for antigenic change of EV-A71, we compared the sequences of two antigenically diverse genotype B4 and B5 strains of EV-A71 and identified substitutions at residues 98, 145, and 164 in the VP1 capsid protein as antigenic determinants. To examine the effects of these three substitutions on antigenicity, we constructed a series of recombinant viruses containing different mutation combinations at these three residues with a reverse genetics system and then investigated the molecular basis of antigenic changes with antigenic cartography. We found that a novel EV-A71 mutant, containing lysine, glutamine, and glutamic acid at the respective residues 98, 145, and 164 in the VP1 capsid protein, exhibited neutralization reduction against patients' antisera and substantially increased virus binding ability to human cells. These observations indicated that this low-neutralization-reactive EV-A71 VP1-98K/145Q/164E mutant potentially increases viral binding ability and that surveillance studies should look out for these mutants, which could compromise vaccine efficacy. IMPORTANCE Emerging and reemerging EV-A71 viruses can cause severe neurological etiology, primarily affecting children, especially around Asia-Pacific countries. We identified a set of mutations in EV-A71 that both reduced neutralization activity against humoral immunity in antisera of patients and healthy adults and greatly increased the viral binding ability to cells. These findings provide important insights for EV-A71 antigenic determinants and emphasize the importance of continuous surveillance, especially after EV-A71 vaccination programs begin. PMID:26339057

Cyclical Patterns of Hand, Foot and Mouth Disease Caused by Enterovirus A71 in Malaysia

PubMed Central

NikNadia, NMN; Sam, I-Ching; Rampal, Sanjay; WanNorAmalina, WMZ; NurAtifah, Ghazali; Verasahib, Khebir; Ong, Chia Ching; MohdAdib, MohdAidinniza; Chan, Yoke Fun

2016-01-01

Enterovirus A71 (EV-A71) is an important emerging pathogen causing large epidemics of hand, foot and mouth disease (HFMD) in children. In Malaysia, since the first EV-A71 epidemic in 1997, recurrent cyclical epidemics have occurred every 2–3 years for reasons that remain unclear. We hypothesize that this cyclical pattern is due to changes in population immunity in children (measured as seroprevalence). Neutralizing antibody titers against EV-A71 were measured in 2,141 residual serum samples collected from children ≤12 years old between 1995 and 2012 to determine the seroprevalence of EV-A71. Reported national HFMD incidence was highest in children <2 years, and decreased with age; in support of this, EV-A71 seroprevalence was significantly associated with age, indicating greater susceptibility in younger children. EV-A71 epidemics are also characterized by peaks of increased genetic diversity, often with genotype changes. Cross-sectional time series analysis was used to model the association between EV-A71 epidemic periods and EV-A71 seroprevalence adjusting for age and climatic variables (temperature, rainfall, rain days and ultraviolet radiance). A 10% increase in absolute monthly EV-A71 seroprevalence was associated with a 45% higher odds of an epidemic (adjusted odds ratio, aOR1.45; 95% CI 1.24–1.69; P<0.001). Every 10% decrease in seroprevalence between preceding and current months was associated with a 16% higher odds of an epidemic (aOR = 1.16; CI 1.01–1.34 P<0.034). In summary, the 2–3 year cyclical pattern of EV-A71 epidemics in Malaysia is mainly due to the fall of population immunity accompanying the accumulation of susceptible children between epidemics. This study will impact the future planning, timing and target populations for vaccine programs. PMID:27010319

EVA Physiology and Medical Considerations Working in the Suit

NASA Technical Reports Server (NTRS)

Parazynski, Scott

2012-01-01

This "EVA Physiology and Medical Considerations Working in the Suit" presentation covers several topics related to the medical implications and physiological effects of suited operations in space from the perspective of a physician with considerable first-hand Extravehicular Activity (EVA) experience. Key themes include EVA physiology working in a pressure suit in the vacuum of space, basic EVA life support and work support, Thermal Protection System (TPS) inspections and repairs, and discussions of the physical challenges of an EVA. Parazynski covers the common injuries and significant risks during EVAs, as well as physical training required to prepare for EVAs. He also shares overall suit physiological and medical knowledge with the next generation of Extravehicular Mobility Unit (EMU) system designers.

Exploration EVA System

NASA Technical Reports Server (NTRS)

Kearney, Lara

2004-01-01

In January 2004, the President announced a new Vision for Space Exploration. NASA's Office of Exploration Systems has identified Extravehicular Activity (EVA) as a critical capability for supporting the Vision for Space Exploration. EVA is required for all phases of the Vision, both in-space and planetary. Supporting the human outside the protective environment of the vehicle or habitat and allow ing him/her to perform efficient and effective work requires an integrated EVA "System of systems." The EVA System includes EVA suits, airlocks, tools and mobility aids, and human rovers. At the core of the EVA System is the highly technical EVA suit, which is comprised mainly of a life support system and a pressure/environmental protection garment. The EVA suit, in essence, is a miniature spacecraft, which combines together many different sub-systems such as life support, power, communications, avionics, robotics, pressure systems and thermal systems, into a single autonomous unit. Development of a new EVA suit requires technology advancements similar to those required in the development of a new space vehicle. A majority of the technologies necessary to develop advanced EVA systems are currently at a low Technology Readiness Level of 1-3. This is particularly true for the long-pole technologies of the life support system.

Information Flow Model of Human Extravehicular Activity Operations

NASA Technical Reports Server (NTRS)

Miller, Matthew J.; McGuire, Kerry M.; Feigh, Karen M.

2014-01-01

Future human spaceflight missions will face the complex challenge of performing human extravehicular activity (EVA) beyond the low Earth orbit (LEO) environment. Astronauts will become increasingly isolated from Earth-based mission support and thus will rely heavily on their own decision-making capabilities and onboard tools to accomplish proposed EVA mission objectives. To better address time delay communication issues, EVA characters, e.g. flight controllers, astronauts, etc., and their respective work practices and roles need to be better characterized and understood. This paper presents the results of a study examining the EVA work domain and the personnel that operate within it. The goal is to characterize current and historical roles of ground support, intravehicular (IV) crew and EV crew, their communication patterns and information needs. This work provides a description of EVA operations and identifies issues to be used as a basis for future investigation.

Extravehicular Activity and Planetary Protection

NASA Technical Reports Server (NTRS)

Buffington, J. A.; Mary, N. A.

2015-01-01

The first human mission to Mars will be the farthest distance that humans have traveled from Earth and the first human boots on Martian soil in the Exploration EVA Suit. The primary functions of the Exploration EVA Suit are to provide a habitable, anthropometric, pressurized environment for up to eight hours that allows crewmembers to perform autonomous and robotically assisted extravehicular exploration, science/research, construction, servicing, and repair operations on the exterior of the vehicle, in hazardous external conditions of the Mars local environment. The Exploration EVA Suit has the capability to structurally interface with exploration vehicles via next generation ingress/egress systems. Operational concepts and requirements are dependent on the mission profile, surface assets, and the Mars environment. This paper will discuss the effects and dependencies of the EVA system design with the local Mars environment and Planetary Protection. Of the three study areas listed for the workshop, EVA identifies most strongly with technology and operations for contamination control.

EVA Wiki - Transforming Knowledge Management for EVA Flight Controllers and Instructors

NASA Technical Reports Server (NTRS)

Johnston, Stephanie

2016-01-01

The EVA (Extravehicular Activity) Wiki was recently implemented as the primary knowledge database to retain critical knowledge and skills in the EVA Operations group at NASA's Johnson Space Center by ensuring that information is recorded in a common, searchable repository. Prior to the EVA Wiki, information required for EVA flight controllers and instructors was scattered across different sources, including multiple file share directories, SharePoint, individual computers, and paper archives. Many documents were outdated, and data was often difficult to find and distribute. In 2011, a team recognized that these knowledge management problems could be solved by creating an EVA Wiki using MediaWiki, a free and open-source software developed by the Wikimedia Foundation. The EVA Wiki developed into an EVA-specific Wikipedia on an internal NASA server. While the technical implementation of the wiki had many challenges, the one of the biggest hurdles came from a cultural shift. Like many enterprise organizations, the EVA Operations group was accustomed to hierarchical data structures and individually-owned documents. Instead of sorting files into various folders, the wiki searches content. Rather than having a single document owner, the wiki harmonized the efforts of many contributors and established an automated revision control system. As the group adapted to the wiki, the usefulness of this single portal for information became apparent. It transformed into a useful data mining tool for EVA flight controllers and instructors, and also for hundreds of other NASA and contract employees. Program managers, engineers, astronauts, flight directors, and flight controllers in differing disciplines now have an easier-to-use, searchable system to find EVA data. This paper presents the benefits the EVA Wiki has brought to NASA's EVA community, as well as the cultural challenges it had to overcome.

Preparation and Properties of Ethylene Vinyl Acetate Copolymer/Silica Nanocomposites in Presence of EVA-g-Acrylic Acid.

PubMed

Tham, Do Quang; Tuan, Vu Manh; Thanh, Dinh Thi Mai; Chinh, Nguyen Thuy; Giang, Nguyen Vu; Trang, Nguyen Thi Thu; Hang, To Thi Xuan; Huong, Ho Thu; Dung, Nguyen Thi Kim; Hoang, Thai

2015-04-01

Here we report a facile approach to enhance the dispersibility of ethylene vinyl acetate copolymer (EVA)/silica nanocomposites (for the EVA/silica nanocomposites and interaction between silica nanoparticles (nanosilica) and EVA by adding EVA-g-acrylic acid (EVAgAA) as a compatibilizer, which was formed by grafting acrylic acid onto EVA chains with the aid of dicumyl peroxide). The above nanocomposites with and without EVAgAA were prepared by melt mixing in a Haake intermixer with different contents of silica and EVAgAA. Their structure and morphology were characterized by Fourier transform infra-red (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), and the mechanical, rheological, dielectrical, and flammability properties of the nanocomposites were also investigated. The FT-IR spectra of the nanocomposites confirmed the formation of hydrogen bonds between the surface silanol groups of nanosilica and C=O groups of EVA and/or EVAgAA. The presence of EVAgAA remarkably increased the intensity of hydrogen bonding between nanosilica and EVA which not only enhanced the dispersion of nanosilica in EVA matrix but also increased the mechanical, viscosity and storage modulus of EVA/silica nanocomposites. In addition, the flammability of EVA/silica nanocomposites is also significantly reduced after the functionalization with EVAgAA. However, the mechanical properties of EVA/silica nanocomposites tended to level off when its content was above 1.5 wt.%. It has also been found that the dielectric constant value of the EVA/EVAgAA/silica nanocomposites is much lower than that of the EVA/silica nanocomposites, which is another evidence of the hydrogen bonding formation between EVAgAA and nanosilica.

Real-Time EVA Troubleshooting

NASA Technical Reports Server (NTRS)

Leestma, David

2013-01-01

David Leestma was EV-1 for the STS-41G extravehicular activity (EVA) with Kathy Sullivan (first American female spacewalker). They conducted an EVA to fully demonstrate the feasibility of refueling satellites from the Space Shuttle, and performed the first contingency EVA task involving the Ku-band antenna. STS-41G was the fourth Space Shuttle mission to perform an EVA, and Leestma related his experiences with training, the spacesuit, and EVA tasks that were conducted on October 11, 1984 during this mission.

Electrical research on solar cells and photovoltaic materials

NASA Technical Reports Server (NTRS)

Orehotsky, J.

1985-01-01

A systematic study of the properties of various polymer pottant materials and of the electrochemical corrosion mechanisms in solar cell materials is required for advancing the technology of terrestrial photovoltaic modules. The items of specific concern in this sponsored research activity involve: (1) kinetics of plasticizer loss in PVB, (2) kinetics of water absorption and desorption in PVB, (3) kinetics of water absorption and desorption in EVA, (4) the electrical properties at PVB as a function of temperature and humidity, (5) the electrical properties of EVA as a function of temperature and humidity, (6) solar cell corrosion characteristics, (7) water absorption effects in PVB and EVA, and (8) ion implantation and radiation effects in PVB and EVA.

Development of Damp-Heat Resistant Self-Primed EVA and Non-EVA Encapsulant Formulations at NREL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F. J.; Jorgensen, G. J.

2005-11-01

Self-primed ethylene-vinyl acetate (EVA) and non-EVA (PMG) encapsulant formulations were developed that have greater resistance to damp heat exposure at 85 deg C and 85% relative humidity (RH) (in terms of adhesion strength to glass substrates) than a commonly used commercial EVA product. The self-primed EVA formulations were developed on the basis of high-performing glass priming formulations that have previously proven to significantly enhance the adhesion strength of unprimed and primed EVA films on glass substrates during damp heat exposure. The PMG encapsulant formulations were based on an ethylene-methylacrylate copolymer containing glycidyl methacrylate.

Effect of VA and MWNT contents on the rheological and physical properties of EVA

NASA Astrophysics Data System (ADS)

Kim, Jong-Ho; Lee, Seungwon; Kim, Byoung Chul; Shin, Bong-Seob; Jeon, Jong-Young; Chae, Dong Wook

2016-02-01

Ethylene vinyl acetate (EVA) copolymers with two different VA contents (15 and 33 wt.%, denoted by EVA15 and EVA33, respectively) were melt compounded with multi-walled carbon nanotubes (MWNTs) and the effect of VA and nanotube contents on the rheological, thermal and morphological properties was investigated. The addition of nanotubes into both EVAs increased the onset temperature of crystallization and broadened the peak, but further addition from 3 wt.% slightly decreased the temperature with increasing nanotube contents. In the wide angle X-ray diffraction patterns the peak of EVA15 was little affected by the presence of nanotubes but that of EVA33 slightly shifted to higher degree and became sharper with increasing nanotube contents. Dynamic viscosity (η') increased with nanotube contents giving abrupt increase at 2 wt.% nanotubes. Loss tangent decreased with increasing nanotube contents exhibiting the plateau-like behavior over most of the frequency range from 2 wt.% nanotubes. In the Casson plot, yield stress increased with nanotube content and its increasing extent was more notable for more VA content. In the Cole-Cole plot, the presence of nanotubes from 2 wt.% gave rise to the deviation from the single master curve by decreasing the slope. The deviated extent of EVA33 became more remarkable with increasing nanotube contents than that of EVA15. The stress-strain curve showed that more improved tensile modulus and yield stress were achieved by the introduction of MWNTs for EVA 33 than for EVA15. Tensile strength of EVA33 increased with increasing nanotube contents, while that of EVA15 decreased.

Space shuttle EVA opportunities. [a technology assessment

NASA Technical Reports Server (NTRS)

Bland, D. A., Jr.

1976-01-01

A technology assessment is presented on space extravehicular activities (EVA) that will be possible when the space shuttle orbiter is completed and launched. The use of EVA in payload systems design is discussed. Also discussed is space crew training. The role of EVA in connection with the Large Space Telescope and Skylab are described. The value of EVA in constructing structures in space and orbital assembly is examined. Excellent color illustrations are provided which show the proposed EVA functions that were described.

[The present status and development of thermal control system of spacesuits for extravehicular activity].

PubMed

Zhao, C Y; Sun, J B; Yuan, X G

1999-04-01

With the extension of extravehicular activity (EVA) duration, the need for more effective thermal control of EVA spacesuits is required. The specific schemes investigated in heat sink system for EVA are discussed, including radiator, ice storage, metal hydride heat pump, phase-change storage/radiator and sublimator. The importance and requirements of automatic thermal control for EVA are also discussed. Existed automatic thermal control for EVA are reviewed. Prospects of further developments of thermal control of spacesuits for EVA are proposed.

One hundred US EVAs: a perspective on spacewalks.

PubMed

Wilde, Richard C; McBarron, James W; Manatt, Scott A; McMann, Harold J; Fullerton, Richard K

2002-01-01

In the 36 years between June 1965 and February 2001, the US human space flight program has conducted 100 spacewalks, or extravehicular activities (EVAs), as NASA officially calls them. EVA occurs when astronauts wearing spacesuits travel outside their protective spacecraft to perform tasks in the space vacuum environment. US EVA started with pioneering feasibility tests during the Gemini Program. The Apollo Program required sending astronauts to the moon and performing EVA to explore the lunar surface. EVA supported scientific mission objectives of the Skylab program, but may be best remembered for repairing launch damage to the vehicle and thus saving the program. EVA capability on Shuttle was initially planned to be a kit that could be flown at will, and was primarily intended for coping with vehicle return emergencies. The Skylab emergency and the pivotal role of EVA in salvaging that program quickly promoted Shuttle EVA to an essential element for achieving mission objectives, including retrieving satellites and developing techniques to assemble and maintain the International Space Station (ISS). Now, EVA is supporting assembly of ISS. This paper highlights development of US EVA capability within the context of the overarching mission objectives of the US human space flight program. c2002 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved.

Coronal CT scan measurements and hearing evolution in enlarged vestibular aqueduct syndrome.

PubMed

Saliba, Issam; Gingras-Charland, Marie-Eve; St-Cyr, Karine; Décarie, Jean-Claude

2012-04-01

To assess the correlation between the enlarged vestibular aqueduct (EVA) diameter and (1) the hearing loss level (mild, moderate, severe and profound and (2) the hearing evolution. The secondary objective was to obtain measurement limits on the coronal plane of the temporal bone CT scan for the diagnosis of EVA. Retrospective study in a tertiary pediatric center. Mastoid CT scans were reviewed to measure the VA diameter at its midpoint and operculum on axial and coronal planes in a pathologic and normal population. We used their serial audiograms to assess the evolution of hearing. 101 EVA was identified out of 1812 temporal bones CT scan from our radiologic database in 8 years. Bone conduction was stable after a mean follow-up of 40.9 ± 32.9 months. PTA has been the most affected in time by the EVA (p=0.006). No correlation was identified between impedancemetry and the diameter of the EVA. On the diagnostic audiogram, 61% of hearing loss were in the mild and moderate hearing levels; at the end of the follow-up 64% of hearing loss are still in the mild and moderate hearing levels. The cut-off values for the coronal midpoint and operculum planes on the CT scan to diagnose an EVA are 2.4 mm and 4.34 mm respectively. Conductive or mixed hearing loss might be the first manifestation of EVA. Coronal CT scan cuts can provide additional information to evaluate EVA especially when axial cuts are not conclusive. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Application of EVA guidelines and design criteria. Volume 2: EVA workstation conceptual designs

NASA Technical Reports Server (NTRS)

Brown, N. E.

1973-01-01

Several EV workstation concepts were developed and are documented. The workstation concepts were developed following a comprehensive analysis of potential EV missions, functions, and tasks as interpreted from NASA and contractor space shuttle and space station studies, mission models, and related reports. The design of a versatile, portable EVA workstation is aimed at reducing the design and development costs for each mission and aiding in the development of on-orbit serviceable payloads.

Vascular Aging: Lessons From Pediatric Hypertension.

PubMed

Litwin, Mieczyslaw; Feber, Janusz; Ruzicka, Marcel

2016-05-01

Hypertension (HTN) in children is associated with early vascular aging (EVA) and underlying immunologic-metabolic abnormalities and accelerated biological maturation. Morphologic and functional vascular changes underlying EVA and HTN in children resemble those seen in the elderly including but not limited to an increase in intima-media thickness (IMT) and arterial stiffness and endothelial dysfunction. Although progeria syndrome leading to EVA and the development of clinically manifested cardiovascular (CV) disease in the second decade of life is a rare hereditary disorder, primary HTN, which is also associated with EVA, is much more common (reported in up to 10% in adolescents). EVA associated with HTN in children leads to the premature development of target organ injury in childhood and CV events in early adulthood. Limited evidence from prospective observational studies in children and adolescents indicates that early lifestyle measures (low salt/low sugar intake and exercise) or pharmacologic treatment of HTN, or both, partially reverses morphologic and functional changes underlying EVA such as an increase in carotid IMT and pulse wave velocity, a decrease in flow-mediated dilation of the brachial artery, and an increase in oxidative stress and visceral fat. Future mechanistic and therapeutic clinical trials are desirable to assess the mechanisms and treatment strategies of EVA in the context of HTN in children and their effect on CV events in early adulthood. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

EVA safety: Space suit system interoperability

NASA Technical Reports Server (NTRS)

Skoog, A. I.; McBarron, J. W.; Abramov, L. P.; Zvezda, A. O.

1995-01-01

The results and the recommendations of the International Academy of Astronautics extravehicular activities (IAA EVA) Committee work are presented. The IAA EVA protocols and operation were analyzed for harmonization procedures and for the standardization of safety critical and operationally important interfaces. The key role of EVA and how to improve the situation based on the identified EVA space suit system interoperability deficiencies were considered.

EVA Training and Development Facilities

NASA Technical Reports Server (NTRS)

Cupples, Scott

2016-01-01

Overview: Vast majority of US EVA (ExtraVehicular Activity) training and EVA hardware development occurs at JSC; EVA training facilities used to develop and refine procedures and improve skills; EVA hardware development facilities test hardware to evaluate performance and certify requirement compliance; Environmental chambers enable testing of hardware from as large as suits to as small as individual components in thermal vacuum conditions.

One-Step Preparation of Long-Term Stable and Flexible CsPbBr3 Perovskite Quantum Dots/Ethylene Vinyl Acetate Copolymer Composite Films for White Light-Emitting Diodes.

PubMed

Li, Yang; Lv, Ying; Guo, Ziquan; Dong, Liubing; Zheng, Jianghui; Chai, Chufen; Chen, Nan; Lu, Yijun; Chen, Chao

2018-05-09

CsPbBr 3 perovskite quantum dots (PQDs)/ethylene vinyl acetate (EVA) composite films were prepared via a one-step method; on the basis of this, both supersaturated recrystallization of CsPbBr 3 PQDs and dissolution of EVA were realized in toluene. The prepared films display outstanding green-emitting performance with high color purity of 92% and photoluminescence (PL) quantum yield of 40.5% at appropriate CsPbBr 3 PQD loading. They possess long-term stable luminescent properties in the air and in water, benefiting from the effective protection of CsPbBr 3 PQDs by the EVA matrix. Besides, the prepared CsPbBr 3 PQDs/EVA films are flexible enough to be repeatedly bent for 1000 cycles while keeping unchanged the PL intensity. The optical properties of the CsPbBr 3 PQDs/EVA films in white light-emitting diodes were also studied by experiments and theoretical simulation. Overall, facile preparation process, good long-term stability, and high flexibility allow our green-emitting CsPbBr 3 PQDs/EVA films to be applied in lighting applications and flexible displays.

Thermal processing of EVA encapsulants and effects of formulation additives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Glick, S.H.

1996-05-01

The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores, in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as formulated EVA films, A9918P and 15295P, and solution-cast films of Elvaxrm (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugardmore » P{trademark}, used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155{degrees}C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.« less

Thermal processing of EVA encapsulants and effects of formulation additives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Glick, S.H.

1996-09-01

The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as-formulated EVA films. A9918P and 15295P, and solution-cast films of Elvax{trademark} (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugard P{trademark},more » used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155 C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.« less

Using surveillance data to estimate pandemic vaccine effectiveness against laboratory confirmed influenza A(H1N1)2009 infection: two case-control studies, Spain, season 2009-2010

PubMed Central

2011-01-01

Background Physicians of the Spanish Influenza Sentinel Surveillance System report and systematically swab patients attended to their practices for influenza-like illness (ILI). Within the surveillance system, some Spanish regions also participated in an observational study aiming at estimating influenza vaccine effectiveness (cycEVA study). During the season 2009-2010, we estimated pandemic influenza vaccine effectiveness using both the influenza surveillance data and the cycEVA study. Methods We conducted two case-control studies using the test-negative design, between weeks 48/2009 and 8/2010 of the pandemic season. The surveillance-based study included all swabbed patients in the sentinel surveillance system. The cycEVA study included swabbed patients from seven Spanish regions. Cases were laboratory-confirmed pandemic influenza A(H1N1)2009. Controls were ILI patients testing negative for any type of influenza. Variables collected in both studies included demographic data, vaccination status, laboratory results, chronic conditions, and pregnancy. Additionally, cycEVA questionnaire collected data on previous influenza vaccination, smoking, functional status, hospitalisations, visits to the general practitioners, and obesity. We used logistic regression to calculate adjusted odds ratios (OR), computing pandemic influenza vaccine effectiveness as (1-OR)*100. Results We included 331 cases and 995 controls in the surveillance-based study and 85 cases and 351 controls in the cycEVA study. We detected nine (2.7%) and two (2.4%) vaccine failures in the surveillance-based and cycEVA studies, respectively. Adjusting for variables collected in surveillance database and swabbing month, pandemic influenza vaccine effectiveness was 62% (95% confidence interval (CI): -5; 87). The cycEVA vaccine effectiveness was 64% (95%CI: -225; 96) when adjusting for common variables with the surveillance system and 75% (95%CI: -293; 98) adjusting for all variables collected. Conclusion Point estimates of the pandemic influenza vaccine effectiveness suggested a protective effect of the pandemic vaccine against laboratory-confirmed influenza A(H1N1)2009 in the season 2009-2010. Both studies were limited by the low vaccine coverage and the late start of the vaccination campaign. Routine influenza surveillance provides reliable estimates and could be used for influenza vaccine effectiveness studies in future seasons taken into account the surveillance system limitations. PMID:22129083

EVA Design, Verification, and On-Orbit Operations Support Using Worksite Analysis

NASA Technical Reports Server (NTRS)

Hagale, Thomas J.; Price, Larry R.

2000-01-01

The International Space Station (ISS) design is a very large and complex orbiting structure with thousands of Extravehicular Activity (EVA) worksites. These worksites are used to assemble and maintain the ISS. The challenge facing EVA designers was how to design, verify, and operationally support such a large number of worksites within cost and schedule. This has been solved through the practical use of computer aided design (CAD) graphical techniques that have been developed and used with a high degree of success over the past decade. The EVA design process allows analysts to work concurrently with hardware designers so that EVA equipment can be incorporated and structures configured to allow for EVA access and manipulation. Compliance with EVA requirements is strictly enforced during the design process. These techniques and procedures, coupled with neutral buoyancy underwater testing, have proven most valuable in the development, verification, and on-orbit support of planned or contingency EVA worksites.

Modified EVA Encapsulant Formulations for Low Temperature Processing: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mei, Z.; Pern, F. J.; Glick, S. H.

2001-10-01

Presented at the 2001 NCPV Program Review Meeting: We have developed several new ethylene-vinyl acetate (EVA) formulations modified on the basis of NREL patented EVA formulations [1]. The new formulations can be cured to a desired gel content of {approx}80% in the ambient at temperatures 20-30 C lower than the typical conditions in vacuum (i.e. {approx}150 C). Glass/glass laminates showed transmittance spectra that are essentially the same as that of EVA 15295P in the visible and NIR regions but higher in the UV region. Results of fluorescence analysis of the ambient-processed new EVA formulations showed the concentrations of the curing-generatedmore » {alpha},{beta}-unsaturated carbonyl chromophores, which are responsible for the UV induced EVA discoloration and photodegradation, were considerably lower than that of EVA 15295P, therefore suggesting a better photochemical stability of new EVA formulations.« less

In Vivo Noninvasive Analysis of Human Forearm Muscle Function and Fatigue: Applications to EVA Operations and Training Maneuvers

NASA Technical Reports Server (NTRS)

Fotedar, L. K.; Marshburn, T.; Quast, M. J.; Feeback, D. L.

1999-01-01

Forearm muscle fatigue is one of the major limiting factors affecting endurance during performance of deep-space extravehicular activity (EVA) by crew members. Magnetic resonance (MR) provides in vivo noninvasive analysis of tissue level metabolism and fluid exchange dynamics in exercised forearm muscles through the monitoring of proton magnetic resonance imaging (MRI) and phosphorus magnetic resonance spectroscopy (P-31-MRS) parameter variations. Using a space glove box and EVA simulation protocols, we conducted a preliminary MRS/MRI study in a small group of human test subjects during submaximal exercise and recovery and following exhaustive exercise. In assessing simulated EVA-related muscle fatigue and function, this pilot study revealed substantial changes in the MR image longitudinal relaxation times (T2) as an indicator of specific muscle activation and proton flux as well as changes in spectral phosphocreatine-to-phosphate (PCr/Pi) levels as a function of tissue bioenergetic potential.

Resource Tracking Model Updates and Trade Studies

NASA Technical Reports Server (NTRS)

Chambliss, Joe; Stambaugh, Imelda; Moore, Michael

2016-01-01

The Resource tracking model has been updated to capture system manager and project manager inputs. Both the Trick/GUNNS RTM simulator and the RTM mass balance spreadsheet have been revised to address inputs from system managers and to refine the way mass balance is illustrated. The revisions to the RTM included addition of a Plasma Pyrolysis Assembly (PPA) to recover hydrogen from Sabatier reactor methane which was vented in the prior version of the RTM. The effect of the PPA on the overall balance of resources in an exploration vehicle is illustrated in the increased recycle of vehicle oxygen. Additionally simulation of EVAs conducted from the exploration module was added. Since the focus of the exploration module is to provide a habitat during deep space operations the EVA simulation approach to EVA is based on ISS EVA protocol and processes. Case studies have been run to show the relative effect of performance changes on vehicle resources.

EVA/ORU model architecture using RAMCOST

NASA Technical Reports Server (NTRS)

Ntuen, Celestine A.; Park, Eui H.; Wang, Y. M.; Bretoi, R.

1990-01-01

A parametrically driven simulation model is presented in order to provide a detailed insight into the effects of various input parameters in the life testing of a modular space suit. The RAMCOST model employed is a user-oriented simulation model for studying the life-cycle costs of designs under conditions of uncertainty. The results obtained from the EVA simulated model are used to assess various mission life testing parameters such as the number of joint motions per EVA cycle time, part availability, and number of inspection requirements. RAMCOST first simulates EVA completion for NASA application using a probabilistic like PERT network. With the mission time heuristically determined, RAMCOST then models different orbital replacement unit policies with special application to the astronaut's space suit functional designs.

Extravehicular Activity (EVA) Technology Development Status and Forecast

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Westheimer, David T.

2010-01-01

Beginning in Fiscal Year (FY) 2011, Extravehicular activity (EVA) technology development became a technology foundational domain under a new program Enabling Technology Development and Demonstration. The goal of the EVA technology effort is to further develop technologies that will be used to demonstrate a robust EVA system that has application for a variety of future missions including microgravity and surface EVA. Overall the objectives will be reduce system mass, reduce consumables and maintenance, increase EVA hardware robustness and life, increase crew member efficiency and autonomy, and enable rapid vehicle egress and ingress. Over the past several years, NASA realized a tremendous increase in EVA system development as part of the Exploration Technology Development Program and the Constellation Program. The evident demand for efficient and reliable EVA technologies, particularly regenerable technologies was apparent under these former programs and will continue to be needed as future mission opportunities arise. The technological need for EVA in space has been realized over the last several decades by the Gemini, Apollo, Skylab, Space Shuttle, and the International Space Station (ISS) programs. EVAs were critical to the success of these programs. Now with the ISS extension to 2028 in conjunction with a current forecasted need of at least eight EVAs per year, the EVA technology life and limited availability of the EMUs will become a critical issue eventually. The current Extravehicular Mobility Unit (EMU) has vastly served EVA demands by performing critical operations to assemble the ISS and provide repairs of satellites such as the Hubble Space Telescope. However, as the life of ISS and the vision for future mission opportunities are realized, a new EVA systems capability could be an option for the future mission applications building off of the technology development over the last several years. Besides ISS, potential mission applications include EVAs for missions to Near Earth Objects (NEO), Phobos, or future surface missions. Surface missions could include either exploration of the Moon or Mars. Providing an EVA capability for these types of missions enables in-space construction of complex vehicles or satellites, hands on exploration of new parts of our solar system, and engages the public through the inspiration of knowing that humans are exploring places that they have never been before. This paper offers insight into what is currently being developed and what the potential opportunities are in the forecast

Study on thermal properties and crystallization behavior of electron beam irradiated ethylene vinyl acetate (EVA)/waste tyre dust (WTD) blends in the presence of polyethylene graft maleic anhydride (PEgMAH)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramli, Syuhada; Ahmad, S. H.; Ratnam, C. T.

2013-11-27

The aim of this article is to show the effects of the electron beam irradiation dose and presence of a compatibiliser on the thermal properties and crystallinity of EVA/WTD blends. The purpose of applying electron beam radiation with doses range 50 to 200 kGy and adding a compatibiliser was to enhance the compatibility of the studied blends and at the same time to investigate the possibility of using this technique in the process of recycling polymeric materials. As the compatibilisers, the polyethylene grafted maleic anhydride (PEgMAH) was utilized, they were added at the amounts of 1-5 phr respectively. The enhancementmore » of thermal properties was accompanied by the following effects, discussed in this article: i) an irradiated EVA/WTD blend at 200kGy was found to improve the thermal properties of EVA, ii) the addition of PEgMAH in EVA/WTD blends and the subsequent irradiation allowed prevention of degradation mechanism. iii) the ΔH{sub f} and crystallinity percentage decrease at higher PEgMAH content.« less

Stress, workload and physiology demand during extravehicular activity: a pilot study.

PubMed

Rai, Balwant; Kaur, Jasdeep; Foing, Bernard H

2012-06-01

Extravehicular activity (EVA), such as exercise performed under unique environmental conditions, is essential for supporting daily living in weightlessness and for further space exploration like long Mars mission. The study was planned stress, workload, and physiological demands of simulated Mars exploration. In this study, the six-person crew lived (24 hours) for 14 days during a short-term stay at the Mars Desert Research Station. The heart rates, salivary cortisol, workload, peak oxygen uptake or maximal aerobic capacity of the crew are measured before, during and after an EVA. Data for heart rate showed the same trend as peak oxygen uptake or maximal aerobic capacity, with a maximal increase to 85% of peak. The rating of subscale showed a significant increase in EVA as compared to run. Salivary cortisol levels and heart rates were increased in both groups, although significant increased of cortisol levels and heart rates more in EVA as compared to hill running crew members. Further study is required on large scale taken into account of limitations of this study and including other physiological and psychological parameters in Mars analog environment.

Frequency of early vascular aging and associated risk factors among an adult population in Latin America: the OPTIMO study.

PubMed

Botto, Fernando; Obregon, Sebastian; Rubinstein, Fernando; Scuteri, Angelo; Nilsson, Peter M; Kotliar, Carol

2018-03-01

The main objective was to estimate the frequency of early vascular aging (EVA) in a sample of subjects from Latin America, with emphasis in young adults. We included 1416 subjects from 12 countries in Latin America who provided information about lifestyle, cardiovascular risk factors (CVRF), and anthropometrics. We measured pulse wave velocity (PWV) as a marker of arterial stiffness, and blood pressure (BP) using an oscillometric device (Mobil-O-Graph). To determine the frequency of EVA, we used multiple linear regression to estimate each subject's PWV expected for his/her age and systolic BP, and compared with observed values to obtain standardized residuals (z-scores). We defined EVA when z-score was ≥1.96. Finally, a multivariable logistic regression analysis was performed to determine baseline characteristics associated with EVA. Mean age was 49.9 ± 15.5 years, male gender was 50.3%. Mean PWV was 7.52 m/s (SD 1.97), mean systolic BP was 125.3 mmHg (SD 16.7) and mean diastolic BP was 78.9 mmHg (SD 12.2). The frequency of EVA was 5.7% in the total population, 9.8% in adults of 40 years or less and 18.7% in those 30 years or less. In these young adults, multiple logistic regression analyses demonstrated that dyslipidemia and hypertension showed an independent association with EVA, and smoking a borderline association (p  =  0.07). In conclusion, the frequency of EVA in a sample from Latin America was around 6%, with higher rates in young adults. These results would support the search of CVRF and EVA during early adulthood.

Effect of electron beam irradiation and microencapsulation on the flame retardancy of ethylene-vinyl acetate copolymer materials during hot water ageing test

NASA Astrophysics Data System (ADS)

Sheng, Haibo; Zhang, Yan; Wang, Bibo; Yu, Bin; Shi, Yongqian; Song, Lei; Kundu, Chanchal Kumar; Tao, Youji; Jie, Ganxin; Feng, Hao; Hu, Yuan

2017-04-01

Microencapsulated ammonium polyphosphate (MCAPP) in combination with polyester polyurethane (TPU) was used to flame retardant ethylene-vinyl acetate copolymer (EVA). The EVA composites with different irradiation doses were immersed in hot water (80 °C) to accelerate ageing process. The microencapsulation and irradiation dose ensured positive impacts on the properties of the EVA composites in terms of better dimensional stability and flame retardant performance. The microencapsulation of APP could lower its solubility in water and the higher irradiation dose led to the more MCAPP immobilized in three dimensional crosslinked structure of the EVA matrix which could jointly enhance the flame retardant and electrical insulation properties of the EVA composites. So, the EVA composites with 180 kGy irradiation dose exhibited better dimensional stability than the EVA composites with 120 kGy due to the higher crosslinking degree. Moreover, the higher irradiation dose lead to the more MCAPP immobilizated in crosslinked three-dimensional structure of EVA, enhancing the flame retardancy and electrical insulation properties of the EVA composites. After ageing test in hot water at 80 °C for 2 weeks, the EVA/TPU/MCAPP composite with 180 kGy could still maintain the UL-94 V-0 rating and the limiting oxygen index (LOI) value was as high as 30%. This investigation indicated the flame retardant EVA cable containing MCAPP could achieve stable properties and lower electrical fire hazard risk during long-term hot water ageing test.

Compiling a Comprehensive EVA Training Dataset for NASA Astronauts

NASA Technical Reports Server (NTRS)

Laughlin, M. S.; Murray, J. D.; Lee, L. R.; Wear, M. L.; Van Baalen, M.

2016-01-01

Training for a spacewalk or extravehicular activity (EVA) is considered a hazardous duty for NASA astronauts. This places astronauts at risk for decompression sickness as well as various musculoskeletal disorders from working in the spacesuit. As a result, the operational and research communities over the years have requested access to EVA training data to supplement their studies. The purpose of this paper is to document the comprehensive EVA training data set that was compiled from multiple sources by the Lifetime Surveillance of Astronaut Health (LSAH) epidemiologists to investigate musculoskeletal injuries. The EVA training dataset does not contain any medical data, rather it only documents when EVA training was performed, by whom and other details about the session. The first activities practicing EVA maneuvers in water were performed at the Neutral Buoyancy Simulator (NBS) at the Marshall Spaceflight Center in Huntsville, Alabama. This facility opened in 1967 and was used for EVA training until the early Space Shuttle program days. Although several photographs show astronauts performing EVA training in the NBS, records detailing who performed the training and the frequency of training are unavailable. Paper training records were stored within the NBS after it was designated as a National Historic Landmark in 1985 and closed in 1997, but significant resources would be needed to identify and secure these records, and at this time LSAH has not pursued acquisition of these early training records. Training in the NBS decreased when the Johnson Space Center in Houston, Texas, opened the Weightless Environment Training Facility (WETF) in 1980. Early training records from the WETF consist of 11 hand-written dive logbooks compiled by individual workers that were digitized at the request of LSAH. The WETF was integral in the training for Space Shuttle EVAs until its closure in 1998. The Neutral Buoyancy Laboratory (NBL) at the Sonny Carter Training Facility near JSC opened in March 1997 and is the current site for US EVA training. Other space agencies also have used water to simulate weightlessness and train for EVAs. Russia has a training facility similar to the NBL named the Hydro Lab. The Hydro Lab began operations at the Gagarin Cosmonaut Training Center (GCTC) in 1980 and has been used extensively to the present. Although a majority of training in the Hydro Lab uses the Russian Orlan suit, a small number of sessions have been conducted using a NASA suit. The Japanese Weightlessness Environment Test System (WETS) went into service at the Tsukuba Space Center in 1997 but was closed in 2011 due to extensive earthquake damage. Several sessions were performed using a NASA suit, but these sessions were short and considered "development" runs. LSAH has assembled records from the WETF, NBL and Hydro Lab. Recording of the EVA training data has changed considerably from 1967 to present. The goal of early record keeping was to track use of hardware components, and the person involved was treated as a suited operator, not as a focus of interest. Records from the past two decades are fairly precise with the person, date, suit type and size noted. On occasion the length of the session was listed, but this data is not included on all records. Records were merged from data sources and extensive cleaning of the records was required since the multiple sources frequently overlapped and duplicated records. To date the LSAH EVA training dataset includes over 12,500 EVA training sessions performed by NASA astronauts since 1981. The following variables are included for most records: Name, Sex, Event date, Event name, HUT type, HUT size, Facility, and Estimated run time. For a smaller subset of records, the following variables are available: Actual run time, Time inverted, and the suit components Waist bearing type, Shoulder harness, Shoulder pads, and Teflon inserts. The LSAH dataset is currently the most complete resource for data regarding EVA training sessions performed by NASA astronauts. However, it is not 100 percent complete since the WETS (Japan) and NBS (Marshall) training facility data were not included. This dataset has been compiled by LSAH to study the relationship of EVA training to musculoskeletal injuries but has many other non-medical applications. This dataset can be provided to other groups in order to respond to program and research questions with appropriate board approvals.

Advanced extravehicular activity systems requirements definition study

NASA Technical Reports Server (NTRS)

1988-01-01

A study to define the requirements for advanced extravehicular activities (AEVA) was conducted. The purpose of the study was to develop an understanding of the EVA technology requirements and to map a pathway from existing or developing technologies to an AEVA system capable of supporting long-duration missions on the lunar surface. The parameters of an AEVA system which must sustain the crewmembers and permit productive work for long periods in the lunar environment were examined. A design reference mission (DRM) was formulated and used as a tool to develop and analyze the EVA systems technology aspects. Many operational and infrastructure design issues which have a significant influence on the EVA system are identified.

Extravehicular Activity Technology Development Status and Forecast

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Westheimer, David T.

2011-01-01

The goal of NASA s current EVA technology effort is to further develop technologies that will be used to demonstrate a robust EVA system that has application for a variety of future missions including microgravity and surface EVA. Overall the objectives will be to reduce system mass, reduce consumables and maintenance, increase EVA hardware robustness and life, increase crew member efficiency and autonomy, and enable rapid vehicle egress and ingress. Over the past several years, NASA realized a tremendous increase in EVA system development as part of the Exploration Technology Development Program and the Constellation Program. The evident demand for efficient and reliable EVA technologies, particularly regenerable technologies was apparent under these former programs and will continue to be needed as future mission opportunities arise. The technological need for EVA in space has been realized over the last several decades by the Gemini, Apollo, Skylab, Space Shuttle, and the International Space Station (ISS) programs. EVAs were critical to the success of these programs. Now with the ISS extension to 2028 in conjunction with a current forecasted need of at least eight EVAs per year, the EVA hardware life and limited availability of the Extravehicular Mobility Units (EMUs) will eventually become a critical issue. The current EMU has successfully served EVA demands by performing critical operations to assemble the ISS and provide repairs of satellites such as the Hubble Space Telescope. However, as the life of ISS and the vision for future mission opportunities are realized, a new EVA systems capability will be needed and the current architectures and technologies under development offer significant improvements over the current flight systems. In addition to ISS, potential mission applications include EVAs for missions to Near Earth Objects (NEO), Phobos, or future surface missions. Surface missions could include either exploration of the Moon or Mars. Providing an EVA capability for these types of missions enables in-space construction of complex vehicles or satellites, hands on exploration of new parts of our solar system, and engages the public through the inspiration of knowing that humans are exploring places that they have never been before. This paper offers insight into what is currently being developed and what the potential opportunities are in the forecast.

Influence of association of "EVA-NBR" on indirect tensile strength of modified bituminous concrete

NASA Astrophysics Data System (ADS)

Chinoun, M.; Soudani, K.; Haddadi, S.

2016-04-01

The aim of this work is to contribute to the improvement of the mechanical properties of bituminous concrete by modification of bituminous concrete. In this study, we present the results of the indirect tensile strength "ITS" of modified bituminous concrete by the combination of two modifiers, one is a plastomer EVA (Ethylene Vinyl Acetate) and the other is a industrial waste from the shoe soles grinding NBR (Nitrile Butadiene Rubber) as crumb rubber. To modify the bitumen a wet process was used. The results show that the modification of bitumen by EVA-NBR combination increases their resistance to the indirect traction "ITS" compared to the bituminous concrete control. The mixture of 5% [50% EVA+ 50% NBR] is given the best result among the other associations.

Extravehicular Activity training and hardware design considerations

NASA Technical Reports Server (NTRS)

Thuot, Pierre J.; Harbaugh, Gregory J.

1993-01-01

Designing hardware that can be successfully operated by EVA astronauts for EVA tasks required to assemble and maintain Space Station Freedom requires a thorough understanding of human factors and of the capabilities and limitations of the space-suited astronaut, as well as of the effect of microgravity environment on the crew member's capabilities and on the overhead associated with EVA. This paper describes various training methods and facilities that are being designed for training EVA astronauts for Space Station assembly and maintenance, taking into account the above discussed factors. Particular attention is given to the user-friendly hardware design for EVA and to recent EVA flight experience.

Current status of EVA degradation in Si modules and interface stability in CdTe/CdS modules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Czanderna, A.W.

1994-06-30

The goals, objectives, background, technical approach, status, and accomplishments on the PV Module Reliability Research Task are summarized for FY 1993. The accomplishments are reported in two elements, ethylene vinyl acetate (EVA) degradation and stability in CdTe/CdS modules. The EVA results are presented under the headings modified EVA and potential EVA replacements, degradation mechanisms, efficiency losses from yellowed EVA, and equipment acquisitions. The results on CdTe/CdS modules are presented under subheadings of stability of the SnO[sub 2]/CdS interface and degradation at the CdTe/CdS interface.

Utilization of ISS to Develop and Test Operational Concepts and Hardware for Low-Gravity Terrestrial EVA

NASA Technical Reports Server (NTRS)

Gast, Matthew A.

2010-01-01

NASA has considerable experience in two areas of Extravehicular Activities (EVA). The first can be defined as microgravity, orbital EVAs. This consists of everything done in low Earth orbit (LEO), from the early, proof of concept EVAs conducted during the Gemini program of the 1960s, to the complex International Space Station (ISS) assembly tasks of the first decade of the 21st century. The second area of expertise is comprised of those EVAs conducted on the lunar surface, under a gravitational force one-sixth that of Earth. This EVA expertise encapsulates two extremes - microgravity and Earthlike gravitation - but is insufficient as humans expand their exploration purview, most notably with respect to spacewalks conducted on very low-gravity bodies, such as near- Earth objects (NEO) and the moons of Mars. The operational and technical challenges of this category of EVA have yet to be significantly examined, and as such, only a small number of operational concepts have been proposed thus far. To ensure mission success, however, EVA techniques must be developed and vetted to allow the selection of operational concepts that can be utilized across an assortment of destinations whose physical characteristics vary. This paper examines the utilization of ISS-based EVAs to test operational concepts and hardware in preparation for a low-gravity terrestrial EVA. While the ISS cannot mimic some of the fundamental challenges of a low-gravity terrestrial EVA - such as rotation rate and surface composition - it may be the most effective test bed available.

Photothermal Stability of an E-Beam Pre-Crosslinked EVA Encapsulant and Its Performance Degradation on a-Si Submodules: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F. J.; Watson, G. L.; Glick, S. H.

2001-10-01

Presented at the 2001 NCPV Program Review Meeting: Study of photothermal stability of special EVA encapsulant by accelerated exposure testing and analysis of causes of performance degradation on a-Si modules.

EVA design: lessons learned.

PubMed

Ross, J L

1994-01-01

Extravehicular Activities (EVAs) are very demanding and specialized space flight activities. There are many aspects to consider in the design of hardware, tools, and procedures to be used on an EVA mission. To help minimize costs and optimize the EVA productivity, experience shows that astronauts should become involved early in the design process.

Development of an EVA systems cost model. Volume 2: Shuttle orbiter crew and equipment translation concepts and EVA workstation concept development and integration

NASA Technical Reports Server (NTRS)

1975-01-01

EVA crewman/equipment translational concepts are developed for a shuttle orbiter payload application. Also considered are EVA workstation systems to meet orbiter and payload requirements for integration of workstations into candidate orbiter payload worksites.

International Space Station (ISS) Plasma Contactor Unit (PCU) Utilization Plan Assessment Update

NASA Technical Reports Server (NTRS)

Hernandez-Pellerano, Amri; Iannello, Christopher J.; Garrett, Henry B.; Ging, Andrew T.; Katz, Ira; Keith, R. Lloyd; Minow, Joseph I.; Willis, Emily M.; Schneider, Todd A.; Whittlesey, Edward J.;

The role of EVA on Space Shuttle. [experimental support and maintenance activities

NASA Technical Reports Server (NTRS)

Carson, M. A.

1974-01-01

The purpose of this paper is to present the history of Extravehicular Activity (EVA) through the Skylab Program and to outline the expected tasks and equipment capabilities projected for the Space Shuttle Program. Advantages offered by EVA as a tool to extend payload capabilities and effectiveness and economic advantages of using EVA will be explored. The presentation will conclude with some guidelines and recommendations for consideration by payload investigators in establishing concepts and designs utilizing EVA support.

Extravehicular Activity/Air Traffic Control (EVA/ATC) test report. [communication links to the astronaut

NASA Technical Reports Server (NTRS)

Tomaro, D. J.

1982-01-01

During extravehicular activity (EVA), communications between the EVA astronaut and the space shuttle orbiter are maintained by means of transceiver installed in the environmental support system backpack. Onboard the orbiter, a transceiver line replaceable unit and its associated equipment performs the task of providing a communications link to the astronaut in the extravehicular activity/air traffic control (EVA/ATC) mode. Results of the acceptance tests that performed on the system designed and fabricated for EVA/ATC testing are discussed.

Influence of menthol and pressure-sensitive adhesives on the in vivo performance of membrane-moderated transdermal therapeutic system of nicardipine hydrochloride in human volunteers.

PubMed

Krishnaiah, Y S R; Satyanarayana, V; Bhaskar, P

2003-05-01

A membrane-moderated transdermal therapeutic system of nicardipine hydrochloride was developed using 2% w/w hydroxypropylcellulose (HPC) gel as a reservoir system containing 5% w/w of menthol as a penetration enhancer. The permeability flux of nicardipine hydrochloride through the ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer. The effect of various pressure-sensitive adhesives (MA-31, MA-38 or TACKWHITE A 4MED on the permeability of nicardipine hydrochloride through EVA 2825 membrane (28% w/w vinyl acetate) or EVA 2825 membrane/skin composite was also studied. The results showed that nicardipine hydrochloride permeability through EVA 2825 membrane coated with TACKWHITE A 4MED/skin composite was higher than that coated with MA-31 or MA-38. Thus, a new transdermal therapeutic system for nicardipine hydrochloride was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE A 4MED, and 2% w/w HPC gel as reservoir containing 5% w/w of menthol as a penetration enhancer. In vivo studies in healthy human volunteers indicated that the TTS of nicardipine hydrochloride, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations for 26h with improved bioavailability in comparison with the immediate release capsule dosage form.

Formulation and in vivo evaluation of membrane-moderated transdermal therapeutic systems of nicardipine hydrochloride using carvone as a penetration enhancer.

PubMed

Krishnaiah, Y S R; Satyanarayana, V; Bhaskar, P

2003-01-01

A membrane-moderated transdermal therapeutic system (TTS) of nicardipine hydrochloride was developed using 2%w/w hydroxy propyl cellulose (HPC) gel as a reservoir system containing 8%w/w of carvone as a penetration enhancer. The permeability flux of nicardipine hydrochloride through ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer. The effect of various pressure-sensitive adhesives (MA-31, MA-38, or TACKWHITE A 4MED) on the permeability of nicardipine hydrochloride through EVA 2825 membrane (28%w/w vinyl acetate) or EVA 2825 membrane/skin composite also was studied. The results showed that nicardipine hydrochloride permeability through EVA 2825 membrane coated with TACKWHITE A 4MED/skin composite was higher than that coated with MA-31 or MA-38. Thus, a new TTS for nicardipine hydrochloride was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE A 4MED and 2%w/w HPC gel as reservoir containing 8%w/w of carvone as a penetration enhancer. The bioavailability studies in healthy human volunteers indicated that the TTS of nicardipine hydrochloride, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations for 23 hr with improved bioavailability in comparison with the immediate-release capsule dosage form.

US space flight experience. Physical exertion and metabolic demand of extravehicular activity: Past, present, and future

NASA Technical Reports Server (NTRS)

Moore, Thomas P.

1989-01-01

A review of physical exertion and metabolic demands of extravehicular activity (EVA) on U.S. astronauts is given. Information is given on EVA during Gemini, Apollo and Skylab missions. It is noted that nominal EVA's should not be overstressful from a cardiovascular standpoint; that manual-intensive EVA's such as are planned for the construction phase of the Space Station can and will be demanding from a muscular standpoint, primarily for the upper extremities; that off-nominal unplanned EVA's can be physically demanding both from an endurance and from a muscular standpoint; and that crewmembers should be physically prepared and capable of performing these EVA's at any time during the mission.

Factors that affect the EVA encapsulant discoloration rate upon accelerated exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.

1994-12-31

Several factors that may affect the net discoloration rate of the ethylene-vinyl acetate (EVA) copolymer encapsulants used in crystalline-Si photovoltaic (c-Si PV) modules upon accelerated exposure have been investigated by employing UV-visible spectrophotometry, spectrocolorimetry, and fluorescence analysis. A number of laminated films, including the two typical EVA formulations, A9918 and 15295, were studied. The results indicate that the rate of EVA discoloration is affected by the (1) curing agent and curing conditions; (2) presence and concentration of curing-generated, UV-excitable chromophores; (3) UV light intensity; (4) loss rate of the UV absorber, Cyasorb UV 531; (5) lamination; (6) film thickness; andmore » (7) photobleaching rate due to the diffusion of air into the laminated films. In general, the loss rate of the UV absorber and the rate of discoloration from light yellow to brown follow a sigmoidal pattern. A reasonable correlation for net changes in transmittance at 420 nm, yellowness index, and fluorescence peak area (or intensity) ratio is obtained as the extent of EVA discoloration progressed.« less

Physiological and technological considerations for Mars mission extravehicular activity

NASA Technical Reports Server (NTRS)

Waligora, James M.; Sedej, Melaine M.

1986-01-01

The nature of the suit is a function of the needs of human physiology, the ambient environment outside the suit, and the type of activity to be accomplished while in the suit. The physiological requirements that must be provided for in the Martian Extravehicular Activity (EVA) suit will be reviewed. The influence of the Martian environment on the EVA suit and EVA capabilities is elaborated, and the Martian environment is compared with the lunar environment. The differences that may influence the EVA design are noted. The type, nature, and duration of activities to be done in transit to Mars and on the Martian surface will be evaluated and the impact of these activities on the requirements for EVA systems will be discussed. Furthermore, the interaction between Martian surface transportation systems and EVA systems will be covered. Finally, options other than EVA will be considered such as robotics, nonanthropometric suits, and vehicles with anthropometric extremities or robotic end effectors.

U.S. Exploration EVA: ConOps, Interfaces and Test Objectives for Airlocks

NASA Technical Reports Server (NTRS)

Buffington, J.

2017-01-01

NASA is moving forward on defining the xEVA System Architecture and its implications to the spacecraft that host exploration EVA systems. This presentation provides an overview of the latest information for NASA's Concept of Operations (ConOps), Interfaces and corresponding Test Objectives for Airlocks hosting the xEVA System.

2014 Decompression Sickness/Extravehicular Activity Risks Standing Review Panel

NASA Technical Reports Server (NTRS)

Steinberg, Susan

2015-01-01

The 2014 Decompression Sickness (DCS)/Extravehicular Activity (EVA) Risks Standing Review Panel (from here on referred to as the SRP) met for a site visit in Houston, TX on November 4 - 5, 2014. The SRP reviewed the updated Evidence Reports for The Risk of Decompression Sickness (from here on referred to as the 2014 DCS Evidence Report) and the Risk of Injury and Compromised Performance due to EVA Operations (from here on referred to as the 2014 EVA Evidence Report), as well as the Research Plans for these Risks. The SRP appreciated the time and effort that the DCS and EVA disciplines put into their review documents and presentations. The SRP felt that the 2014 DCS Evidence Report and the 2014 EVA Evidence Reports were very thorough and addressed the majority of the known DCS and EVA issues. The researchers at NASA Johnson Space Center (JSC) have the knowledge base to deal with the DCS and EVA issues. Overall, the SRP thinks the DCS and EVA research teams have compiled excellent reports which address the majority of the literature and background information.

Trials and tribulations of carotid artery stenting: The Interventionalists' perspective on SAPPHIRE, EVA-3S, and SPACE Trials.

PubMed

Harjai, Kishore J; Mehta, Rajendra H

2007-10-01

Three recently completed randomized studies of carotid artery stenting (CAS) versus endarterectomy-Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE), Endarterectomy versus Stenting in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S), and Stent-Supported Percutaneous Angioplasty of the Carotid Artery versus Endarterectomy (SPACE)-reached vividly different conclusions about the safety of stenting versus endarterectomy. The methodologies of these studies differed from each other in many respects. In an attempt to explain the disparate results of SAPPHIRE, EVA-3S, and SPACE, this focused review compares and contrasts these studies, with specific reference to inclusion and exclusion criteria, technical considerations, and the experience level of the interventional operators.

Potential roles for EVA and telerobotics in a unified worksite

NASA Astrophysics Data System (ADS)

Akin, David; Howard, Russel D.

1993-02-01

Although telerobotics and extravehicular activity (EVA) are often portrayed as competitive approaches to space operations, ongoing research in the Space Systems Laboratory (SSL) has demonstrated the utility of cooperative roles in an integrated EVA/telerobotic work site. Working in the neutral buoyancy simulation environment, tests were performed on interactive roles or EVA subjects and telerobots in structural assembly and satellite servicing tasks. In the most elaborate of these tests to date, EVA subjects were assisted by the SSL's Beam Assembly Teleoperator (BAT) in several servicing tasks planned for Hubble Space Telescope, using the high-fidelity crew training article in the NASA Marshall Neutral Buoyancy Simulator. These tests revealed several shortcomings in the design of BAT for satellite servicing and demonstrated the utility of a free-flying or RMS-mounted telerobot for providing EVA crew assistance. This paper documents the past tests, including the use of free-flying telerobots to effect the rescue of a simulated incapacitated EVA subject, and details planned future efforts in this area, including the testing of a new telerobotic system optimized for the satellite servicing role, the development of dedicated telerobotic devices designed specifically for assisting EVA crew, and conceptual approaches to advanced EVA/telerobotic operations such as the Astronaut Operations Vehicle.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Eisgruber, I.L.; Micheels, R.H.

The effects of ethylene-vinyl acetate (EVA) discoloration due to accelerated field or laboratory exposure on the encapsulated silicon (Si) solar cells or EVA/glass laminates were characterized quantitatively by using non-invasive, non-destructive ultraviolet-visible (UV-vis) spectrophotometry, spectrocolorimetry, spectrofluorometry, scanning laser OBIC (optical beam induced current) spectroscopy, and current-voltage (I-V) and quantum efficiency (QE) measurements. The results show that the yellowness index (YI) measured directly over the AR-coated solar cells under the glass superstrate increased from the range of {minus}80 to {minus}90 to the range of {minus}20 to 15 as the EVA changed from clear to brown. The ratio of two fluorescence emissionmore » peak areas generally increased from 1.45 to 5.69 as browning increased, but dropped to 4.21 on a darker EVA. For a solar cell with brown EVA in the central region, small-area grating QE measurements and scanning laser OBIC analysis between the brown and clear EVA regions showed that the quantum efficiency loss at 633 nm was 42%--48% of the loss at 488 nm, due to a reduced decrease of transmittance in browned EVA at the longer wavelengths. The portion of the solar cell under the browned EVA showed a decrease of {approximately}36% in efficiency, as compared to the cell efficiency under clear EVA. Transmittance loss at 633 nm was 38% of the loss at 488 nm for a light yellow-brown EVA/glass laminate that showed a small increase of 10 in the yellowness index.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Eisgruber, I.L.; Micheels, R.H.

The effects of ethylene-vinyl acetate (EVA) discoloration due to accelerated field or laboratory exposure on the encapsulated silicon (Si) solar cells or EVA/glass laminates were characterized quantitatively by using non-invasive, non-destructive ultraviolet-visible (UV-vis) spectrophotometry, spectrocolorimetry, spectrofluorometry, scanning laser OBIC (optical beam induced current) spectroscopy, and current-voltage (I-V) and quantum efficiency (QE) measurements. The results show that the yellowness index (YI) measured directly over the AR-coated solar cells under the glass superstrate increased from the range of -80 to -90 to the range of -20 to 15 as the EVA changed from clear to brown. The ratio of two fluorescence emissionmore » peak areas generally increased from 1.45 to 5.69 as browning increased, but dropped to 4.21 on a darker EVA. For a solar cell with brown EVA in the central region, small-area grating QE measurements and scanning laser OBIC analysis between the brown and clear EVA regions showed that the quantum efficiency loss at 633 nm was 42%-48% of the loss at 488 nm, due to a reduced decrease of transmittance in browned EVA at the longer wavelengths. The portion of the solar cell under the browned EVA showed a decrease of {approximately}36% in efficiency, as compared to the cell efficiency under clear EVA. Transmittance loss at 633 nm was 38% of the loss at 488 nm for a light yellow-brown EVA/glass laminate that showed a small increase of 10 in the yellowness index.« less

2BC Non-Structural Protein of Enterovirus A71 Interacts with SNARE Proteins to Trigger Autolysosome Formation.

PubMed

Lai, Jeffrey K F; Sam, I-Ching; Verlhac, Pauline; Baguet, Joël; Eskelinen, Eeva-Liisa; Faure, Mathias; Chan, Yoke Fun

2017-07-04

Viruses have evolved unique strategies to evade or subvert autophagy machinery. Enterovirus A71 (EV-A71) induces autophagy during infection in vitro and in vivo. In this study, we report that EV-A71 triggers autolysosome formation during infection in human rhabdomyosarcoma (RD) cells to facilitate its replication. Blocking autophagosome-lysosome fusion with chloroquine inhibited virus RNA replication, resulting in lower viral titres, viral RNA copies and viral proteins. Overexpression of the non-structural protein 2BC of EV-A71 induced autolysosome formation. Yeast 2-hybrid and co-affinity purification assays showed that 2BC physically and specifically interacted with a N -ethylmaleimide-sensitive factor attachment receptor (SNARE) protein, syntaxin-17 (STX17). Co-immunoprecipitation assay further showed that 2BC binds to SNARE proteins, STX17 and synaptosome associated protein 29 (SNAP29). Transient knockdown of STX17, SNAP29, and microtubule-associated protein 1 light chain 3B (LC3B), crucial proteins in the fusion between autophagosomes and lysosomes) as well as the lysosomal-associated membrane protein 1 (LAMP1) impaired production of infectious EV-A71 in RD cells. Collectively, these results demonstrate that the generation of autolysosomes triggered by the 2BC non-structural protein is important for EV-A71 replication, revealing a potential molecular pathway targeted by the virus to exploit autophagy. This study opens the possibility for the development of novel antivirals that specifically target 2BC to inhibit formation of autolysosomes during EV-A71 infection.

Incorporation of nisin in poly (ethylene-co-vinyl acetate) films by melt processing: a study on the antimicrobial properties.

PubMed

Scaffaro, Roberto; Botta, Luigi; Marineo, Sandra; Puglia, Anna Maria

2011-07-01

Both industry and academia have shown a growing interest in materials with antimicrobial properties suitable for food packaging applications. In this study, we prepared and characterized thin films of ethylene-co-vinyl acetate (EVA) copolymer with antimicrobial properties. The films were prepared with a film blowing process by incorporating a nisin preparation as an antimicrobial agent in the melt. Two grades of EVA containing 14 and 28% (wt/wt) vinyl acetate (EVA 14 and EVA 28, respectively) and two commercial formulations of nisin with different nominal activities were used. The effect of the nisin concentration also was evaluated. The films with the highest antimicrobial activity were those formulated with nisin at the highest activity and EVA with the highest content of vinyl acetate. The use of the commercial formulation of nisin with high activity in the EVA films allowed reduction in the amount of nisin needed to provide antimicrobial properties. Consequently, the mechanical properties of these films were only slightly inferior to those of the pure polymers. In contrast, films prepared by incorporating more of the nisin with lower activity had poor mechanical properties. The effect of different processing temperatures used in the preparation of the films on the antimicrobial properties of the films also was evaluated. The materials displayed antimicrobial properties even when they were prepared at temperatures as high as 160 °C, probably because of the very short processing time (60 to 90 s) required for preparation. Copyright ©, International Association for Food Protection

2BC Non-Structural Protein of Enterovirus A71 Interacts with SNARE Proteins to Trigger Autolysosome Formation

PubMed Central

Lai, Jeffrey K. F.; Sam, I-Ching; Verlhac, Pauline; Baguet, Joël; Faure, Mathias

2017-01-01

Viruses have evolved unique strategies to evade or subvert autophagy machinery. Enterovirus A71 (EV-A71) induces autophagy during infection in vitro and in vivo. In this study, we report that EV-A71 triggers autolysosome formation during infection in human rhabdomyosarcoma (RD) cells to facilitate its replication. Blocking autophagosome-lysosome fusion with chloroquine inhibited virus RNA replication, resulting in lower viral titres, viral RNA copies and viral proteins. Overexpression of the non-structural protein 2BC of EV-A71 induced autolysosome formation. Yeast 2-hybrid and co-affinity purification assays showed that 2BC physically and specifically interacted with a N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein, syntaxin-17 (STX17). Co-immunoprecipitation assay further showed that 2BC binds to SNARE proteins, STX17 and synaptosome associated protein 29 (SNAP29). Transient knockdown of STX17, SNAP29, and microtubule-associated protein 1 light chain 3B (LC3B), crucial proteins in the fusion between autophagosomes and lysosomes) as well as the lysosomal-associated membrane protein 1 (LAMP1) impaired production of infectious EV-A71 in RD cells. Collectively, these results demonstrate that the generation of autolysosomes triggered by the 2BC non-structural protein is important for EV-A71 replication, revealing a potential molecular pathway targeted by the virus to exploit autophagy. This study opens the possibility for the development of novel antivirals that specifically target 2BC to inhibit formation of autolysosomes during EV-A71 infection. PMID:28677644

Use MACES IVA Suit for EVA Mobility Evaluations

NASA Technical Reports Server (NTRS)

Watson, Richard D.

2014-01-01

The use of an Intra-Vehicular Activity (IVA) suit for a spacewalk or Extra-Vehicular Activity (EVA) was evaluated for mobility and usability in the Neutral Buoyancy Lab (NBL) environment. The Space Shuttle Advanced Crew Escape Suit (ACES) has been modified (MACES) to integrate with the Orion spacecraft. The first several missions of the Orion MPCV spacecraft will not have mass available to carry an EVA specific suit so any EVA required will have to be performed by the MACES. Since the MACES was not designed with EVA in mind, it was unknown what mobility the suit would be able to provide for an EVA or if a person could perform useful tasks for an extended time inside the pressurized suit. The suit was evaluated in multiple NBL runs by a variety of subjects including crewmembers with significant EVA experience. Various functional mobility tasks performed included: translation, body positioning, carrying tools, body stabilization, equipment handling, and use of tools. Hardware configurations included with and without TMG, suit with IVA gloves and suit with EVA gloves. Most tasks were completed on ISS mockups with existing EVA tools. Some limited tasks were completed with prototype tools on a simulated rocky surface. Major findings include: demonstration of the ability to weigh-out the suit, understanding the need to have subjects perform multiple runs prior to getting feedback, determination of critical sizing factors, and need for adjustment of suit work envelop. The early testing has demonstrated the feasibility of EVA's limited duration and limited scope. Further testing is required with more flight like tasking and constraints to validate these early results. If the suit is used for EVA, it will require mission specific modifications for umbilical management or PLSS integration, safety tether attachment, and tool interfaces. These evaluations are continuing through calendar year 2014.

Stress, Workload and Physiology Demand During Extravehicular Activity: A Pilot Study

PubMed Central

Rai, Balwant; Kaur, Jasdeep; Foing, Bernard H

2012-01-01

Background: Extravehicular activity (EVA), such as exercise performed under unique environmental conditions, is essential for supporting daily living in weightlessness and for further space exploration like long Mars mission. Aim: The study was planned stress, workload, and physiological demands of simulated Mars exploration. Materials and Methods: In this study, the six-person crew lived (24 hours) for 14 days during a short-term stay at the Mars Desert Research Station. The heart rates, salivary cortisol, workload, peak oxygen uptake or maximal aerobic capacity of the crew are measured before, during and after an EVA. Results: Data for heart rate showed the same trend as peak oxygen uptake or maximal aerobic capacity, with a maximal increase to 85% of peak. The rating of subscale showed a significant increase in EVA as compared to run. Salivary cortisol levels and heart rates were increased in both groups, although significant increased of cortisol levels and heart rates more in EVA as compared to hill running crew members. Conclusion: Further study is required on large scale taken into account of limitations of this study and including other physiological and psychological parameters in Mars analog environment. PMID:22754877

Walking to Olympus: An EVA Chronology

NASA Technical Reports Server (NTRS)

Portree, David S. F.; Trevino, Robert C.

1997-01-01

Spacewalkers enjoy a view of Earth once reserved for Apollo, Zeus, and other denizens of Mt. Olympus. During humanity's first extravehicular activity (EVA), Alexei Leonov floated above Gibraltar, the rock ancient seafarers saw as the gateway to the great unknown Atlantic. The symbolism was clear, Leonov stepped past a new Gibraltar when he stepped into space. More than 32 years and 154 EVAs later, Jerry Linenger conducted an EVA with Vladimir Tsibliyev as part of International Space Station Phase 1. They floated together above Gibraltar. Today the symbolism has new meaning: humanity is starting to think of stepping out of Earth orbit, space travel's new Gibraltar, and perhaps obtaining a new olympian view, a close-up look at Olympus Mons on Mars. Walking to Olympus: An EVA Chronology chronicles the 154 EVAs conducted from March 1965 to April 1997. It is intended to make clear the crucial role played by EVA in the history of spaceflight, as well as to chronicle the large body of EVA "lessons learned." Russia and the U.S. define EVA differently. Russian cosmonauts are said to perform EVA any time they are in vacuum in a space suit. A U.S. astronaut must have at least his head outside his spacecraft before he is said to perform an EVA. The difference is based in differing spacecraft design philoso- phies. Russian and Soviet spacecraft have always had a specialized airlock through which the EVA cosmonaut egressed, leaving the main habitable volume of the spacecraft pressurized. The U.S. Gemini and Apollo vehicles, on the other hand, depressurized their entire habitable volume for egress. In this document, we apply the Russian definition to Russian EVAS, and the U.S. definition to U.S. EVAS. Thus, for example, Gemini 4 Command Pilot James McDivitt does not share the honor of being first American spacewalker with Ed White, even though he was suited and in vacuum when White stepped out into space. Non-EVA spaceflights are listed in the chronology to provide context and to display the large num- ber of flights in which EVA played a role. This approach also makes apparent significant EVA gaps, for example, the U.S. gap between 1985 and 1991 following the Challenger accident. This NASA History Monograph is an edited extract from an extensive EVA Chronology and Reference Book being produced by the EVA Project Office, NASA Johnson Space Center, Houston, Texas. The larger work will be published as part of the NASA Formal Series in 1998. The authors gratefully acknowledge the assistance rendered by Max Ary, Ashot Bakunts, Gert-Jan Bartelds, Frank Cepollina, Andrew Chaikin, Phillip Clark, Richard Fullerton, Steven Glenn, Linda Godwin, Jennifer Green, Greg Harris, Clifford Hess, Jeffrey Hoffman, David Homan, Steven Hopkins, Nicholas Johnson, Eric Jones, Neville Kidger, Joseph Kosmo, Alexei Lebedev, Mark Lee, James LeBlanc, Dmitri Leshchenskii, Jerry Linenger, Igor Lissov, James McBarron, Clay McCullough, Joseph McMann, Story Musgrave, Dennis Newkirk, James Oberg, Joel Powell, Lee Saegesser, Andy Salmon, Glen Swanson, Joseph Tatarewicz, Kathy Thornton, Chris Vandenberg, Charles Vick, Bert Vis, David Woods, Mike Wright, John Young, and Keith Zimmerman. Special thanks to Laurie Buchanan, John Charles, Janet Kovacevich, Joseph Loftus, Sue McDonald, Martha Munies, Colleen Rapp, and Jerry Ross. Any errors remain the responsibility of the authors.

Study of roles of remote manipulator systems and EVA for shuttle mission support, volume 1

NASA Technical Reports Server (NTRS)

Malone, T. B.; Micocci, A. J.

1974-01-01

Alternate extravehicular activity (EVA) and remote manipulator system (RMS) configurations were examined for their relative effectiveness in performing an array of representative shuttle and payload support tasks. Initially a comprehensive analysis was performed of payload and shuttle support missions required to be conducted exterior to a pressurized inclosure. A set of task selection criteria was established, and study tasks were identified. The EVA and RMS modes were evaluated according to their applicability for each task and task condition. The results are summarized in tabular form, showing the modes which are chosen as most effective or as feasible for each task/condition. Conclusions concerning the requirements and recommendations for each mode are presented.

Study on structure and hydrophobicity of PP/EVA co-blending membrane: Quenching rate

NASA Astrophysics Data System (ADS)

Tang, Na; Li, Zhao; Hua, Xinxin

2017-03-01

Isotactic polypropylene (iPP)/ethylene vinyl acetate (EVA) co-blending hydrophobic microporous membranes for vacuum membrane distillation (VMD) were prepared via thermally induced phase separation (TIPS). In the process of preparation, quenching rate has a great influence on the membrane morphology.

EVA console personnel during STS-61 simulations

NASA Image and Video Library

1993-09-01

Susan P. Rainwater monitors an extravehicular activity (EVA) simulation from the EVA console at JSC's Mission Control Center (MCC) during joint integrated simulations for the STS-61 mission. Astronauts assigned to extravehicular activity (EVA) tasks with the Hubble Space Telescope (HST) were simultaneously rehearsing in a neutral buoyancy tank at the Marshall Space Flight Center (MSFC) in Alabama.

ChEVAS: Combining Suprarenal EVAS with Chimney Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Torella, Francesco, E-mail: f.torella@liverpool.ac.uk; Chan, Tze Y., E-mail: tze.chan@rlbuht.nhs.uk; Shaikh, Usman, E-mail: usman.shaikh@rlbuht.nhs.uk

2015-10-15

Endovascular sealing with the Nellix{sup ®} endoprosthesis (EVAS) is a new technique to treat infrarenal abdominal aortic aneurysms. We describe the use of endovascular sealing in conjunction with chimney stents for the renal arteries (chEVAS) in two patients, one with a refractory type Ia endoleak and an expanding aneurysm, and one with a large juxtarenal aneurysm unsuitable for fenestrated endovascular repair (EVAR). Both aneurysms were successfully excluded. Our report confirms the utility of chEVAS in challenging cases, where suprarenal seal is necessary. We suggest that, due to lack of knowledge on its durability, chEVAS should only been considered when moremore » conventional treatment modalities (open repair and fenestrated EVAR) are deemed difficult or unfeasible.« less

Prospective assessment of clinical symptoms associated with enterovirus and parechovirus genotypes in a multicenter study in Dutch children.

PubMed

de Crom, S C M; Rossen, J W A; de Moor, R A; Veldkamp, E J M; van Furth, A M; Obihara, C C

2016-04-01

Human non-polio enterovirus (EV) and human parechovirus (HPeV) are important pathogens of viral infection and aseptic meningitis in children. The aim of this study is to prospectively compare the incidence, clinical signs, blood and cerebrospinal fluid in EV and HPeV infected children. To compare the clinical symptoms and laboratory data of children with different EV and HPeV genotypes. This study is part of a multicenter prospective cohort study. Children were included in 3 different hospitals in The Netherlands from 2008 to 2011. Of 285 included patients, 140 (49%) had EV and 44 (15%) HPeV infection. Of children with EV infection 9 (6%) had EV-A, 109 (78%) EV-B, 12 (9%) had a non-type able EV and in 10 (7%) no genotyping was performed. Of children with HPeV infection, 24 (55%) had HPeV-3, 6 (14%) HPeV-1, 2 (5%) HPeV-4 and 1 (2%) HPeV-6. Meningitis was more frequent in EV than in HPeV infected children (54% vs. 36%, p=0.046), and in EV-B than EV-A infected children (60 vs. 33%). In contrast gastroenteritis was more frequent in HPeV than EV infected children (30% vs. 15%, p=0.030), and significantly more in HPeV-1 than HPeV-3 infected children (p<0.001). EV infection is more often associated with meningitis and HPeV infection more often with a gastro-enteritis. EV genotype B infection is more often associated with meningitis than EV genotype A infection. HPeV-1 infection was more often associated with gastroenteritis than HPeV-3 infection. Copyright © 2016 Elsevier B.V. All rights reserved.

The space station assembly phase: Flight telerobotic servicer feasibility. Volume 2: Methodology and case study

NASA Technical Reports Server (NTRS)

Smith, Jeffrey H.; Gyamfi, Max A.; Volkmer, Kent; Zimmerman, Wayne F.

1987-01-01

A methodology is described for examining the feasibility of a Flight Telerobotic Servicer (FTS) using two assembly scenarios, defined at the EVA task level, for the 30 shuttle flights (beginning with MB-1) over a four-year period. Performing all EVA tasks by crew only is compared to a scenario in which crew EVA is augmented by FTS. A reference FTS concept is used as a technology baseline and life-cycle cost analysis is performed to highlight cost tradeoffs. The methodology, procedure, and data used to complete the analysis are documented in detail.

Space shuttle EVA/IVA support equipment requirements study. Volume 1: Final summary report

NASA Technical Reports Server (NTRS)

1973-01-01

A study was conducted to determine the support equipment requirements for space shuttle intravehicular and extravehicular activities. The subjects investigated are; (1) EVA/IVA task identification and analysis,. (2) primary life support system, (3) emergency life support system, (4) pressure suit assembly, (5) restraints, (6) work site provision, (7) emergency internal vehicular emergencies, and (8) vehicular interfaces.

Phylodynamics of Enterovirus A71-Associated Hand, Foot, and Mouth Disease in Viet Nam.

PubMed

Geoghegan, Jemma L; Tan, Le Van; Kühnert, Denise; Halpin, Rebecca A; Lin, Xudong; Simenauer, Ari; Akopov, Asmik; Das, Suman R; Stockwell, Timothy B; Shrivastava, Susmita; Ngoc, Nghiem My; Uyen, Le Thi Tam; Tuyen, Nguyen Thi Kim; Thanh, Tran Tan; Hang, Vu Thi Ty; Qui, Phan Tu; Hung, Nguyen Thanh; Khanh, Truong Huu; Thinh, Le Quoc; Nhan, Le Nguyen Thanh; Van, Hoang Minh Tu; Viet, Do Chau; Tuan, Ha Manh; Viet, Ho Lu; Hien, Tran Tinh; Chau, Nguyen Van Vinh; Thwaites, Guy; Grenfell, Bryan T; Stadler, Tanja; Wentworth, David E; Holmes, Edward C; Van Doorn, H Rogier

2015-09-01

Enterovirus A71 (EV-A71) is a major cause of hand, foot, and mouth disease (HFMD) and is particularly prevalent in parts of Southeast Asia, affecting thousands of children and infants each year. Revealing the evolutionary and epidemiological dynamics of EV-A71 through time and space is central to understanding its outbreak potential. We generated the full genome sequences of 200 EV-A71 strains sampled from various locations in Viet Nam between 2011 and 2013 and used these sequence data to determine the evolutionary history and phylodynamics of EV-A71 in Viet Nam, providing estimates of the effective reproduction number (Re) of the infection through time. In addition, we described the phylogeography of EV-A71 throughout Southeast Asia, documenting patterns of viral gene flow. Accordingly, our analysis reveals that a rapid genogroup switch from C4 to B5 likely took place during 2012 in Viet Nam. We show that the Re of subgenogroup C4 decreased during the time frame of sampling, whereas that of B5 increased and remained >1 at the end of 2013, corresponding to a rise in B5 prevalence. Our study reveals that the subgenogroup B5 virus that emerged into Viet Nam is closely related to variants that were responsible for large epidemics in Malaysia and Taiwan and therefore extends our knowledge regarding its associated area of endemicity. Subgenogroup B5 evidently has the potential to cause more widespread outbreaks across Southeast Asia. EV-A71 is one of many viruses that cause HFMD, a common syndrome that largely affects infants and children. HFMD usually causes only mild illness with no long-term consequences. Occasionally, however, severe infection may arise, especially in very young children, causing neurological complications and even death. EV-A71 is highly contagious and is associated with the most severe HFMD cases, with large and frequent epidemics of the virus recorded worldwide. Although major advances have been made in the development of a potential EV-A71 vaccine, there is no current prevention and little is known about the patterns and dynamics of EV-A71 spread. In this study, we utilize full-length genome sequence data obtained from HFMD patients in Viet Nam, a geographical region where the disease has been endemic since 2003, to characterize the phylodynamics of this important emerging virus. Copyright © 2015 Geoghegan et al.

Phylodynamics of Enterovirus A71-Associated Hand, Foot, and Mouth Disease in Viet Nam

PubMed Central

Kühnert, Denise; Halpin, Rebecca A.; Lin, Xudong; Simenauer, Ari; Akopov, Asmik; Das, Suman R.; Stockwell, Timothy B.; Shrivastava, Susmita; Ngoc, Nghiem My; Uyen, Le Thi Tam; Tuyen, Nguyen Thi Kim; Thanh, Tran Tan; Hang, Vu Thi Ty; Qui, Phan Tu; Hung, Nguyen Thanh; Khanh, Truong Huu; Thinh, Le Quoc; Nhan, Le Nguyen Thanh; Van, Hoang Minh Tu; Viet, Do Chau; Tuan, Ha Manh; Viet, Ho Lu; Hien, Tran Tinh; Chau, Nguyen Van Vinh; Thwaites, Guy; Grenfell, Bryan T.; Stadler, Tanja; Wentworth, David E.; Holmes, Edward C.; Van Doorn, H. Rogier

2015-01-01

ABSTRACT Enterovirus A71 (EV-A71) is a major cause of hand, foot, and mouth disease (HFMD) and is particularly prevalent in parts of Southeast Asia, affecting thousands of children and infants each year. Revealing the evolutionary and epidemiological dynamics of EV-A71 through time and space is central to understanding its outbreak potential. We generated the full genome sequences of 200 EV-A71 strains sampled from various locations in Viet Nam between 2011 and 2013 and used these sequence data to determine the evolutionary history and phylodynamics of EV-A71 in Viet Nam, providing estimates of the effective reproduction number (Re) of the infection through time. In addition, we described the phylogeography of EV-A71 throughout Southeast Asia, documenting patterns of viral gene flow. Accordingly, our analysis reveals that a rapid genogroup switch from C4 to B5 likely took place during 2012 in Viet Nam. We show that the Re of subgenogroup C4 decreased during the time frame of sampling, whereas that of B5 increased and remained >1 at the end of 2013, corresponding to a rise in B5 prevalence. Our study reveals that the subgenogroup B5 virus that emerged into Viet Nam is closely related to variants that were responsible for large epidemics in Malaysia and Taiwan and therefore extends our knowledge regarding its associated area of endemicity. Subgenogroup B5 evidently has the potential to cause more widespread outbreaks across Southeast Asia. IMPORTANCE EV-A71 is one of many viruses that cause HFMD, a common syndrome that largely affects infants and children. HFMD usually causes only mild illness with no long-term consequences. Occasionally, however, severe infection may arise, especially in very young children, causing neurological complications and even death. EV-A71 is highly contagious and is associated with the most severe HFMD cases, with large and frequent epidemics of the virus recorded worldwide. Although major advances have been made in the development of a potential EV-A71 vaccine, there is no current prevention and little is known about the patterns and dynamics of EV-A71 spread. In this study, we utilize full-length genome sequence data obtained from HFMD patients in Viet Nam, a geographical region where the disease has been endemic since 2003, to characterize the phylodynamics of this important emerging virus. PMID:26085170

Applications of EVA guidelines and design criteria. Volume 3: EVA systems cost model formating

NASA Technical Reports Server (NTRS)

Brown, N. E.

1973-01-01

The development of a model for estimating the impact of manned EVA costs on future payloads is discussed. Basic information on the EV crewman requirements, equipment, physical and operational characteristics, and vehicle interfaces is provided. The cost model is being designed to allow system designers to quantify the impact of EVA on vehicle and payload systems.

EVA-SCRAM operations

NASA Technical Reports Server (NTRS)

Flanigan, Lee A.; Tamir, David; Weeks, Jack L.; Mcclure, Sidney R.; Kimbrough, Andrew G.

1994-01-01

This paper wrestles with the on-orbit operational challenges introduced by the proposed Space Construction, Repair, and Maintenance (SCRAM) tool kit for Extra-Vehicular Activity (EVA). SCRAM undertakes a new challenging series of on-orbit tasks in support of the near-term Hubble Space Telescope, Extended Duration Orbiter, Long Duration Orbiter, Space Station Freedom, other orbital platforms, and even the future manned Lunar/Mars missions. These new EVA tasks involve welding, brazing, cutting, coating, heat-treating, and cleaning operations. Anticipated near-term EVA-SCRAM applications include construction of fluid lines and structural members, repair of punctures by orbital debris, refurbishment of surfaces eroded by atomic oxygen, and cleaning of optical, solar panel, and high emissivity radiator surfaces which have been degraded by contaminants. Future EVA-SCRAM applications are also examined, involving mass production tasks automated with robotics and artificial intelligence, for construction of large truss, aerobrake, and reactor shadow shield structures. Realistically achieving EVA-SCRAM is examined by addressing manual, teleoperated, semi-automated, and fully-automated operation modes. The operational challenges posed by EVA-SCRAM tasks are reviewed with respect to capabilities of existing and upcoming EVA systems, such as the Extravehicular Mobility Unit, the Shuttle Remote Manipulating System, the Dexterous End Effector, and the Servicing Aid Tool.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F. J.; Glick, S. H.

We have conducted a series of accelerated exposure test (AET) studies for various crystalline-Si (c-Si) and amorphous-Si (a-Si) cell samples that were encapsulated with different superstrates, pottants, and substrates. Nonuniform browning patterns of ethylene vinyl acetate (EVA) pottants were observed for glass/EVA/glass-encapsulated c-Si cell samples under solar simulator exposures at elevated temperatures. The polymer/polymer-configured laminates with Tedlar or Tefzel did not discolor because of photobleaching reactions, but yellowed with polyester or nylon top films. Delamination was observed for the polyester/EVA layers on a-Si minimodules and for a polyolefin-based thermoplastic pottant at high temperatures. For all tested c-Si cell samples, irregularmore » changes in the current-voltage parameters were observed that could not be accounted for simply by the transmittance changes of the superstrate/pottant layers. Silicone-type adhesives used under UV-transmitting polymer top films were observed to cause greater cell current/efficiency loss than EVA or polyethylene pottants.« less

An Effective Division of Labor Between Human and Robotic Agents Performing a Cooperative Assembly Task

NASA Technical Reports Server (NTRS)

Rehnmark, Fredrik; Bluethmann, William; Rochlis, Jennifer; Huber, Eric; Ambrose, Robert

2003-01-01

NASA's Human Space Flight program depends heavily on spacewalks performed by human astronauts. These so-called extra-vehicular activities (EVAs) are risky, expensive and complex. Work is underway to develop a robotic astronaut's assistant that can help reduce human EVA time and workload by delivering human-like dexterous manipulation capabilities to any EVA worksite. An experiment is conducted to evaluate human-robot teaming strategies in the context of a simplified EVA assembly task in which Robonaut, a collaborative effort with the Defense Advanced Research Projects Agency (DARPA), an anthropomorphic robot works side-by-side with a human subject. Team performance is studied in an effort to identify the strengths and weaknesses of each teaming configuration and to recommend an appropriate division of labor. A shared control approach is developed to take advantage of the complementary strengths of the human teleoperator and robot, even in the presence of significant time delay.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Lik Fai, E-mail: rickieclf@yahoo.com.hk; Cheung, Kwok Fai; Chan, Kwong Man

Nellix Endovascular Aneurysm Sealing (EVAS) system is a new concept and technology of abdominal aortic aneurysm (AAA) repair. Elective EVAS using Nellix device was performed for a 83-year-old man with AAA. 2-month post-EVAS CTA surveillance demonstrated mild enlargement of aneurysmal sac and separation of the EndoBags, but without detectable endoleak. The patient developed sudden AAA rupture with retroperitoneal hematoma at about 4 months after EVAS. We postulated that early enlargement of aneurysmal sac and separation of EndoBags of Nellix devices after EVAS, even without detectable endoleak, might indicate significant aneurysmal wall weakening with increased risk of later AAA rupture. To themore » best of the authors’ knowledge, this was the first reported case of aortic rupture after EVAS without detectable endoleak during and after the procedure.« less

Crosscutting Development- EVA Tools and Geology Sample Acquisition

NASA Technical Reports Server (NTRS)

2011-01-01

Exploration to all destinations has at one time or another involved the acquisition and return of samples and context data. Gathered at the summit of the highest mountain, the floor of the deepest sea, or the ice of a polar surface, samples and their value (both scientific and symbolic) have been a mainstay of Earthly exploration. In manned spaceflight exploration, the gathering of samples and their contextual information has continued. With the extension of collecting activities to spaceflight destinations comes the need for geology tools and equipment uniquely designed for use by suited crew members in radically different environments from conventional field geology. Beginning with the first Apollo Lunar Surface Extravehicular Activity (EVA), EVA Geology Tools were successfully used to enable the exploration and scientific sample gathering objectives of the lunar crew members. These early designs were a step in the evolution of Field Geology equipment, and the evolution continues today. Contemporary efforts seek to build upon and extend the knowledge gained in not only the Apollo program but a wealth of terrestrial field geology methods and hardware that have continued to evolve since the last lunar surface EVA. This paper is presented with intentional focus on documenting the continuing evolution and growing body of knowledge for both engineering and science team members seeking to further the development of EVA Geology. Recent engineering development and field testing efforts of EVA Geology equipment for surface EVA applications are presented, including the 2010 Desert Research and Technology Studies (Desert RATs) field trial. An executive summary of findings will also be presented, detailing efforts recommended for exotic sample acquisition and pre-return curation development regardless of planetary or microgravity destination.

Energy Expenditure During Extravehicular Activity Through Apollo

NASA Technical Reports Server (NTRS)

Paul, Heather L.

2011-01-01

Monitoring crew health during manned space missions has always been an important factor to ensure that the astronauts can complete the missions successfully and within safe physiological limits. The necessity of real-time metabolic rate monitoring during extravehicular activities (EVAs) came into question during the Gemini missions, when the energy expenditure required to complete EVA tasks exceeded the life support capabilities for cooling and humidity control and crewmembers (CMs) ended the EVAs fatigued and overworked. This paper discusses the importance of real-time monitoring of metabolic rate during EVA, and provides a historical look at energy expenditure during EVA through the Apollo program.

Suited for Space

NASA Technical Reports Server (NTRS)

Kosmo, Joseph J.

2006-01-01

This viewgraph presentation describes the basic functions of space suits for EVA astronauts. Space suits are also described from the past, present and future space missions. The contents include: 1) Why Do You Need A Space Suit?; 2) Generic EVA System Requirements; 3) Apollo Lunar Surface Cycling Certification; 4) EVA Operating Cycles for Mars Surface Missions; 5) Mars Surface EVA Mission Cycle Requirements; 6) Robustness Durability Requirements Comparison; 7) Carry-Weight Capabilities; 8) EVA System Challenges (Mars); 9) Human Planetary Surface Exploration Experience; 10) NASA Johnson Space Center Planetary Analog Activities; 11) Why Perform Remote Field Tests; and 12) Other Reasons Why We Perform Remote Field Tests.

Evaluation of an Anthropometric Human Body Model for Simulated EVA Task Assessment

NASA Technical Reports Server (NTRS)

Etter, Brad

1996-01-01

One of the more mission-critical tasks performed in space is extravehicular activity (EVA) which requires the astronaut to be external to the station or spacecraft, and subsequently at risk from the many threats posed by space. These threats include, but are not limited to: no significant atmosphere, harmful electromagnetic radiation, micrometeoroids, and space debris. To protect the astronaut from this environment, a special EVA suit is worn which is designed to maintain a sustainable atmosphere (at 1/3 atmosphere) and provide protection against the hazards of space. While the EVA suit serves these functions well, it does impose limitations on the astronaut as a consequence of the safety it provides. Since the astronaut is in a virtual vacuum, any atmospheric pressure inside the suit serves to pressurize the suit and restricts mobility of flexible joints (such as fabric). Although some of the EVA suit joints are fixed, rotary-style joints, most of the mobility is achieved by the simple flexibility of the fabric. There are multiple layers of fabric, each of which serves a special purpose in the safety of the astronaut. These multiple layers add to the restriction of motion the astronaut experiences in the space environment. Ground-based testing is implemented to evaluate the capability of EVA-suited astronauts to perform the various tasks in space. In addition to the restriction of motion imposed by the EVA suit, most EVA activity is performed in a micro-gravity (weight less) environment. To simulate weightlessness EVA-suited testing is performed in a neutral buoyancy simulator (NBS). The NBS is composed of a large container of water (pool) in which a weightless environment can be simulated. A subject is normally buoyant in the pressurized suit; however he/she can be made neutrally buoyant with the addition of weights. In addition, most objects the astronaut must interface with in the NBS sink in water and flotation must be added to render them "weightless". The implementation of NBS testing has proven to invaluable in the assessment of EVA activities performed with the Orbiter and is considered to be a key step in the construction of the International Space Station (ISS). While the NBS testing is extremely valuable, it does require considerable overhead to maintain and operate. It has been estimated that the cost of utilizing the facility is approximately $10,000 per day. Therefore it is important to maximize the utility of NBS testing for optimal results. One important aspect to consider in any human/worksite interface is the considerable wealth of anthropometric and ergonomic data available. A subset of this information specific to EVA activity is available in NASA standard 3000. The difficulty in implementing this data is that most of the anthropometric information is represented in a two-dimensional format. This poses some limitations in complete evaluation of the astronaut's capabilities in a three-dimensional environment. Advances in computer hardware and software have provided for three-dimensional design and implementation of hardware with the advance of computer aided design (CAD) software. There are a number of CAD products available and most companies and agencies have adopted CAD as a fundamental aspect of the design process. Another factor which supports the use of CAD is the implementation of computer aided manufacturing (CAM) software and hardware which provides for rapid prototyping and decreases the time to product in the design process. It is probable that most hardware to be accessed by astronauts in EVA or IVA (intravehicular activity) has been designed by a CAD system, and is therefore represented in three-dimensional space for evaluation. Because of the implementation of CAD systems and the movement towards early prototyping, a need has arisen in industry and government for tools which facilitate the evaluation of ergonomic consideration in a three-dimensional environment where the hardware has been designed by the CAD tools. One such product is Jack which was developed by the University of Pennsylvania with funding from several government agencies, including NASA. While the primary purpose of Jack is to model human figures in a ground-based (gravity) environment, it can be utilized to evaluate EVA-suited activities as well. The effects of simulated gravity must be turned off by turning off "behaviors". Although Jack provides human figures for manipulation, the primary instrument to be evaluated for EVA mobility is the work envelope provided by the EVA suit. An EVA Jack suit model has been developed by NASA-JSC and was utilized in this study. This suit model provided a more restrictive motion environment as expected for an EVA suited subject. As part of this study, the anthropometric dimensions for a 50th percentile male were compared with basic anthropometric data and were found to be representative for the population group expected in the NASA flight program. The joints for the suit were created in a manner which provided consistent performance with EVA reach envelopes published in NASA standard #3000.

Molecular Comparison and Evolutionary Analyses of VP1 Nucleotide Sequences of New African Human Enterovirus 71 Isolates Reveal a Wide Genetic Diversity

PubMed Central

Nougairède, Antoine; Joffret, Marie-Line; Deshpande, Jagadish M.; Dubot-Pérès, Audrey; Héraud, Jean-Michel

2014-01-01

Most circulating strains of Human enterovirus 71 (EV-A71) have been classified primarily into three genogroups (A to C) on the basis of genetic divergence between the 1D gene, which encodes the VP1 capsid protein. The aim of the present study was to provide further insights into the diversity of the EV-A71 genogroups following the recent description of highly divergent isolates, in particular those from African countries, including Madagascar. We classified recent EV-A71 isolates by a large comparison of 3,346 VP1 nucleotidic sequences collected from GenBank. Analysis of genetic distances and phylogenetic investigations indicated that some recently-reported isolates did not fall into the genogroups A-C and clustered into three additional genogroups, including one Indian genogroup (genogroup D) and 2 African ones (E and F). Our Bayesian phylogenetic analysis provided consistent data showing that the genogroup D isolates share a recent common ancestor with the members of genogroup E, while the isolates of genogroup F evolved from a recent common ancestor shared with the members of the genogroup B. Our results reveal the wide diversity that exists among EV-A71 isolates and suggest that the number of circulating genogroups is probably underestimated, particularly in developing countries where EV-A71 epidemiology has been poorly studied. PMID:24598878

SLC26A4 mutation testing for hearing loss associated with enlargement of the vestibular aqueduct

PubMed Central

Ito, Taku; Muskett, Julie; Chattaraj, Parna; Choi, Byung Yoon; Lee, Kyu Yup; Zalewski, Christopher K; King, Kelly A; Li, Xiangming; Wangemann, Philine; Shawker, Thomas; Brewer, Carmen C; Alper, Seth L; Griffith, Andrew J

2014-01-01

Pendred syndrome (PS) is characterized by autosomal recessive inheritance of goiter associated with a defect of iodide organification, hearing loss, enlargement of the vestibular aqueduct (EVA), and mutations of the SLC26A4 gene. However, not all EVA patients have PS or SLC26A4 mutations. Two mutant alleles of SLC26A4 are detected in ¼ of North American or European EVA populations, one mutant allele is detected in another ¼ of patient populations, and no mutations are detected in the other ½. The presence of two mutant alleles of SLC26A4 is associated with abnormal iodide organification, increased thyroid gland volume, increased severity of hearing loss, and bilateral EVA. The presence of a single mutant allele of SLC26A4 is associated with normal iodide organification, normal thyroid gland volume, less severe hearing loss and either bilateral or unilateral EVA. When other underlying correlations are accounted for, the presence of a cochlear malformation or the size of EVA does not have an effect on hearing thresholds. This is consistent with observations of an Slc26a4 mutant mouse model of EVA in which hearing loss is independent of endolymphatic hydrops or inner ear malformations. Segregation analyses of EVA in families suggest that the patients carrying one mutant allele of SLC26A4 have a second, undetected mutant allele of SLC26A4, and the probability of a sibling having EVA is consistent with its segregation as an autosomal recessive trait. Patients without any mutations are an etiologically heterogeneous group in which siblings have a lower probability of having EVA. SLC26A4 mutation testing can provide prognostic information to guide clinical surveillance and management, as well as the probability of EVA affecting a sibling. PMID:25960948

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Glick, S.H.; Czanderna, A.W.

Results from extensive studies of the commercial ethylene vinyl acetate (EVA) formulations show that the UV absorber and curing-generated UV-excitable, {alpha},{beta}-unsaturated carbonyl chromophores facilitate the EVA discoloration, which is further enhanced by curing-generated acetic acid and probably residual peroxide curing agent also. Formation and concentration of the UV-excitable chromophores are substantially promoted by the antioxidant, Naugard P. The discoloration rate is greater under higher UV light intensity and temperatures. Heating in the dark at elevated temperatures (e.g., 85&hthinsp;{degree}C) in the air for {approximately}200 days only results in light yellowing. The discoloration reactions compete with photobleaching reactions, which destroy curing-generated chromophoresmore » and result in non-discoloring of EVA. By using better performance stabilizers to minimize the curing-generated UV-excitable chromophores, a new fast curing agent, and no UV absorber, the NREL-developed EVA formulations show a superior photothermal stability against browning to the commercial counterparts. Alternatively, the discoloration rate of the commercial EVA pottants can be considerably reduced by using UV-filtering glass superstrates that largely inhibit the UV-induced photooxidation reactions, or completely eliminated by using air-permeable polymer superstrate films that enable photobleaching reactions. {copyright} {ital 1999 American Institute of Physics.}« less

Study of montmorillonite nanoparticles and electron beam irradiation interaction of ethylene vinyl acetate (EVA)/de-vulcanized waste rubber thermoplastic composites

NASA Astrophysics Data System (ADS)

Bee, Soo-Tueen; Sin, Lee Tin; Hoe, Tie Teck; Ratnam, C. T.; Bee, Soo Ling; Rahmat, A. R.

2018-05-01

The purpose of this work was to investigate the effects of montmorillonite (MMT) loading level and electron beam irradiation on the physical-mechanical properties and thermal stability of ethylene vinyl acetate (EVA)- devulcanised waste rubber blends. The addition of MMT particles has significantly increased the d-spacing and interchain separation of deflection peak (0 0 2) of MMT particles. This indicates that MMT particles have effectively intercalated in polymer matrix of EVA-devulcanised waste rubber blends. Besides, the application of electron beam irradiation dosages <150 kGy could also significantly induce the effective intercalation effect of MMT particles in polymer matrix by introducing crosslinking networks. The increasing of electron beam irradiation dosages up to 250 kGy has gradually increased the gel content of all EVA-devulcanized rubber blends by inducing the formation of crosslinking networks in polymer matrix. Also, the tensile strength of all EVA-devulcanized waste rubber blends was gradually increased when irradiated up to 150 kGy. This is due to the occurrence of crosslinking networks by irradiation could significantly provide reinforcement effect to polymer matrix by effectively transferring the stress applied on polymer matrix throughout the whole polymer matrix.

The properties of neutron shielding and flame retardant of EVA polymer after modified by EB accelerator

NASA Astrophysics Data System (ADS)

Wang, Guo-hui; He, Man-li; Jiang, Dan-feng; He, Fan; Chang, Shu-quan; Dai, Yao-dong

2017-11-01

According to the requirements for neutron shielding and flame retardant properties of some nuclear devices, a new kind of polymer composite materials based on ethylene and vinyl acetate (EVA) polymer have been studied. EVA is the copolymer of ethylene and vinyl acetate, It can be used as materials for applications due to its flexibility, good processability, and low cost. Insulating EVA can be used for cable sheath, automotive sound damping and many other appication. Boron nitride (BN), zinc borate (ZB), magnesium hydroxide (MH) and EVA consisted the compounds with the properties of neutron shielding and flame retardant. With increasing of the contents of BN and ZB, the neutron shielding performance of materials increased up to 33.08%. With the increasing contents of MH and ZB as flame retardant, oxygen index of material have been improved. The elongation at break and tensile strength of material decreased with the increasing of filler powders. Sheet E was chosen and modified by electron beam accelerator in different doses. After modification by electron beam irradiation the sheets showed varying degrees of transformation in the OI, neutron shielding rate and mechanical properties.

Electron beam irradiation induced compatibilization of immiscible polyethylene/ethylene vinyl acetate (PE/EVA) blends: Mechanical properties and morphology stability

NASA Astrophysics Data System (ADS)

Entezam, Mehdi; Aghjeh, Mir Karim Razavi; Ghaffari, Mehdi

2017-02-01

Gel content, mechanical properties and morphology of immiscible PE/EVA blends irradiated by high energy electron beam were studied. The results of gel content measurements showed that the capability of cross-linking of the blend samples increased with an increase of the EVA composition. Also, the gel content for most compositions of the blends displayed a positive deviation from the additive rule. The results of mechanical properties showed that the tensile strength and elongation at break of the samples increased and decreased, respectively, with irradiation dose. On the other hand, the mechanical properties of the irradiated blends also depicted a positive deviation from additive rule contrary to the un-irradiated blends. A synergistic effect observed for the mechanical properties improvement of the irradiated blends and it was attributed to the probable formation of the PE-graft-EVA copolymers at the interface of the blends during the irradiation process. A theoretical analysis revealed that irradiation induced synergistic effect was more significant for EVA-rich blends with weaker interfacial interaction as compared to PE-rich blends. The morphological analysis indicated that the blend morphology was not affected obviously, whereas it was stabilized by irradiation.

The economic value added (EVA) resulting from medical care of functional amblyopia, strabismus, (pathologies of binocular vision) and asthma.

PubMed

Beauchamp, Cynthia L; Felius, Joost; Beauchamp, George R

2010-01-01

Value analysis in health care calculates the economic value added (EVA) that results from improvements in health and health care. Our purpose was to develop an EVA model and to apply the model to typical and hypothetical (instantaneous and perfect) cures for amblyopia, surgical strabismus and asthma, as another, but non-ophthalmological disease standard for comparison, in the United States. The model is based on changes in utility and longevity, the associated incremental costs, and an estimate of the value of life. Univariate sensitivity analyses were performed to arrive at a plausible range of outcomes. For the United States, the EVA for current practice amblyopia care is 12.9B dollars (billion) per year, corresponding to a return on investment (ROI) of 10.4% per yr. With substantial increases in investment aimed at maximal improvement ("perfect cure"), the EVA is 32.7B per yr, with ROI of 5.3% per yr. The EVA for typical surgical strabismus care is 10.3B per yr. A perfect cure may yield EVA of 9.6B per yr. The EVA for asthma is 1317B per yr (ROI 20.4% per yr.., while a perfect cure may yield EVA of 110 B per yr. Sensitivity analysis demonstrated the relatively large effects of incidence, utility, and longevity, while incremental costs have a relatively minor effect on the EVA. The economic value added by improvements in patient-centered outcomes is very large. Failing to make the necessary investments in research, prevention, detection, prompt treatment and rehabilitation of these diseases, at virtually any conceivable cost, appears economically, medically, morally and ethically deficient and consequently wasteful at very least economically for our society.

Enlarged Vestibular Aqueducts and Childhood Hearing Loss

MedlinePlus

... EVA. However, this is a rare event in commercial aircraft with pressurized cabins. If you have EVA, ... EVA, will benefit from learning other forms of communication, such as sign language or cued speech, or ...

Climbing the Extravehicular Activity (EVA) Wall - Safely

NASA Technical Reports Server (NTRS)

Fuentes, Jose; Greene, Stacie

2010-01-01

The success of the EVA team, that includes the EVA project office, Crew Office, Mission Operations, Engineering and Safety, is assured by the full integration of all necessary disciplines. Safety participation in all activities from hardware development concepts, certification and crew training, provides for a strong partnership within the team. Early involvement of Safety on the EVA team has mitigated risk and produced a high degree of mission success.

Health and Safety Benefits of Small Pressurized Suitport Rovers as EVA Surface Support Vehicles

NASA Technical Reports Server (NTRS)

Gernhardt, Michael L.; Abercromby, Andrew F. J.

2008-01-01

Pressurized safe-haven providing SPE protection and decompression sickness (DCS) treatment capabilities within 20 mins at all times. Up to 50% reduction in time spent in EVA suits (vs. Unpressurized Rovers) for equal or greater Boots-on-Surface EVA exploration time. Reduces suit-induced trauma and provides improved options for nutrition, hydration, and waste-management. Time spent inside SPR during long translations may be spent performing resistive and cardiovascular exercise. Multiple shorter EVAs versus single 8 hr EVAs increases DCS safety and decreases prebreathe requirements. SPRs also offer many potential operational, engineering and exploration benefits not addressed here.

Energy Expenditure During Extravehicular Activity Through Apollo

NASA Technical Reports Server (NTRS)

Paul, Heather L.

2012-01-01

Monitoring crew health during manned space missions has always been an important factor to ensure that the astronauts can complete the missions successfully and within safe physiological limits. The necessity of real-time metabolic rate monitoring during extravehicular activities (EVAs) came into question during the Gemini missions, when the energy expenditure required to complete EVA tasks exceeded the life support capabilities for cooling and humidity control and, as a result, crew members ended the EVAs fatigued and overworked. This paper discusses the importance of real-time monitoring of metabolic rate during EVAs, and provides a historical look at energy expenditure during EVAs through the Apollo Program.

Suited crewmember productivity.

PubMed

Barer, A S; Filipenkov, S N

1994-01-01

Analysis of the extravehicular activity (EVA) sortie experience gained in the former Soviet Union and physiologic hygienic aspect of space suit design and development shows that crewmember productivity is related to the following main factors: -space suit microclimate (gas composition, pressure and temperature); -limitation of motion activity and perception, imposed by the space suit; -good crewmember training in the ground training program; -level of crewmember general physical performance capabilities in connection with mission duration and intervals between sorties; -individual EVA experience (with accumulation) at which workmanship improves, while metabolism, physical and emotional stress decreases; -concrete EVA duration and work rate; -EVA bioengineering, including selection of tools, work station, EVA technology and mechanization.

Regenerable thermal control and carbon dioxide control techniques for use in advanced extravehicular protective systems

NASA Technical Reports Server (NTRS)

Williams, J. L.; Copeland, R. J.; Nebbon, B. W.

1972-01-01

The most promising closed CO2 control concept identified by this study is the solid pellet, Mg(OH2)2 system. Two promising approaches to closed thermal control were identified. The AHS system uses modular fusible heat sinks, with a contingency evaporative mode, to allow maximum EVA mobility. The AHS/refrigerator top-off subsystem requires an umbilical to minimize expendables, but less EVA time is used to operate the system, since there is no requirement to change modules. Both of these subsystems are thought to be practical solutions to the problem of providing closed heat rejection for an EVA system.

Human-Robot Teaming in a Multi-Agent Space Assembly Task

NASA Technical Reports Server (NTRS)

Rehnmark, Fredrik; Currie, Nancy; Ambrose, Robert O.; Culbert, Christopher

2004-01-01

NASA's Human Space Flight program depends heavily on spacewalks performed by pairs of suited human astronauts. These Extra-Vehicular Activities (EVAs) are severely restricted in both duration and scope by consumables and available manpower. An expanded multi-agent EVA team combining the information-gathering and problem-solving skills of humans with the survivability and physical capabilities of robots is proposed and illustrated by example. Such teams are useful for large-scale, complex missions requiring dispersed manipulation, locomotion and sensing capabilities. To study collaboration modalities within a multi-agent EVA team, a 1-g test is conducted with humans and robots working together in various supporting roles.

Modeling Oxygen Prebreathe Protocols for Exploration Extravehicular Activities Using Variable Pressure Suits

NASA Technical Reports Server (NTRS)

Abercromby, Andrew F. J.; Conkin, Johnny; Gernhardt, Michael L.

2017-01-01

Exploration missions are expected to use variable pressure extravehicular activity (EVA) spacesuits as well as a spacecraft "exploration atmosphere" of 56.5 kPa (8.2 psia), 34% O2, both of which provide the possibility of reducing the oxygen prebreathe times necessary to reduce decompression sickness (DCS) risk. Previous modeling work predicted 8.4% DCS risk for an EVA beginning at the exploration atmosphere, followed by 15 minutes of in-suit O2 prebreathe, and 6 hours of EVA at 29.6 kPa (4.3 psia). In this study we model notional prebreathe protocols for a variable pressure suit where the exploration atmosphere is unavailable.

Simplified Abrasion Test Methodology for Candidate EVA Glove Lay-Ups

NASA Technical Reports Server (NTRS)

Rabel, Emily; Aitchison, Lindsay

2015-01-01

During the Apollo Program, space suit outer-layer fabrics were badly abraded after performing just a few extravehicular activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots that penetrated the outer-layer fabric into the thermal protection layers after less than 8 hrs of surface operations. Current plans for the exploration planetary space suits require the space suits to support hundreds of hours of EVA on a lunar or Martian surface, creating a challenge for space suit designers to utilize materials advances made over the last 40 years and improve on the space suit fabrics used in the Apollo Program. Over the past 25 years the NASA Johnson Space Center Crew and Thermal Systems Division has focused on tumble testing as means of simulating wear on the outer layer of the space suit fabric. Most recently, in 2009, testing was performed on 4 different candidate outer layers to gather baseline data for future use in design of planetary space suit outer layers. In support of the High Performance EVA Glove Element of the Next Generation Life Support Project, testing a new configuration was recently attempted in which require 10% of the fabric per replicate of that need in 2009. The smaller fabric samples allowed for reduced per sample cost and flexibility to test small samples from manufacturers without the overhead to have a production run completed. Data collected from this iteration was compared to that taken in 2009 to validate the new test method. In addition the method also evaluated the fabrics and fabric layups used in a prototype thermal micrometeoroid garment (TMG) developed for EVA gloves under the NASA High Performance EVA Glove Project. This paper provides a review of previous abrasion studies on space suit fabrics, details methodologies used for abrasion testing in this particular study, results of the validation study, and results of the TMG testing.

Moments applied in the manual assembly of space structures - Ease biomechanics results from STS-61B. [Experimental Assembly of Structures in EVA

NASA Technical Reports Server (NTRS)

Cousins, D.; Akin, D. L.

1989-01-01

Measurements of the level and pattern of moments applied in the manual assembly of a space structure were made in extravehicular activity (EVA) and neutral buoyancy simulation (NBS). The Experimental Assembly of Structures in EVA program included the repeated assembly of a 3.6 m tetrahedral truss structure in EVA on STS-61B after extensive neutral buoyancy crew training. The flight and training structures were of equivalent mass and geometry to allow a direct correlation between EVA and NBS performance. A stereo photographic motion camera system was used to reconstruct in three dimensions rotational movements of structural beams during assembly. Moments applied in these manual handling tasks were calculated on the basis of the reconstructed movements taking into account effects of inertia, drag and virtual mass. Applied moments of 2.0 Nm were typical for beam rotations in EVA. Corresponding applied moments in NBS were typically up to five times greater. Moments were applied as impulses separated by several seconds of coasting in both EVA and NBS. Decelerating impulses were only infrequently observed in NBS.

Evaluation of Encapsulant Adhesion to Surface Metallization of Photovoltaic Cells: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tracy, Jared; Dauskardt, Reinhold; Bosco, Nick

Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of EVA encapsulant to screen printed silver metallization was evaluated. At room temperature, the fracture energy, Gc [J/m2], of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/AR coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 hours of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2, while that of themore » EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and elevated temperature, and may explain the propensity for delamination to occur at metallized surfaces in the field.« less

Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tracy, Jared; Bosco, Nick; Dauskardt, Reinhold

Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of ethylene vinyl acetate (EVA) encapsulant to screen-printed silver metallization was evaluated. At room temperature, the fracture energy Gc [J/m2] of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/antireflective (AR) coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 h of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2 whilemore » that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and chemical byproducts at elevated temperature, which in part accounts for the propensity of metalized surfaces to delaminate in the field.« less

Extravehicular activity space suit interoperability.

PubMed

Skoog, A I; McBarron JW 2nd; Severin, G I

1995-10-01

The European Agency (ESA) and the Russian Space Agency (RKA) are jointly developing a new space suit system for improved extravehicular activity (EVA) capabilities in support of the MIR Space Station Programme, the EVA Suit 2000. Recent national policy agreements between the U.S. and Russia on planned cooperations in manned space also include joint extravehicular activity (EVA). With an increased number of space suit systems and a higher operational frequency towards the end of this century an improved interoperability for both routine and emergency operations is of eminent importance. It is thus timely to report the current status of ongoing work on international EVA interoperability being conducted by the Committee on EVA Protocols and Operations of the International Academy of Astronauts initiated in 1991. This paper summarises the current EVA interoperability issues to be harmonised and presents quantified vehicle interface requirements for the current U.S. Shuttle EMU and Russian MIR Orlan DMA and the new European/Russian EVA Suit 2000 extravehicular systems. Major critical/incompatible interfaces for suits/mother-craft of different combinations are discussed, and recommendations for standardisations given.

European Space Agency (ESA) Mission Specialist Nicollier trains in JSC's WETF

NASA Technical Reports Server (NTRS)

1987-01-01

European Space Agency (ESA) Mission Specialist (MS) Claude Nicollier (left) is briefed by Randall S. McDaniel on Space Shuttle extravehicular activity (EVA) tools and equipment prior to donning an extravehicular mobility unit and participating in an underwater EVA simulation in JSC's Weightless Environment Training Facility (WETF) Bldg 29 pool. Nicollier is holding the EMU mini workstation. Other equipment on the table includes EVA tool caddies and EVA crewmember safety tethers.

Early Enlargement of Aneurysmal Sac and Separation of EndoBags of Nellix Endovascular Aneurysm Sealing System as Signs of Increased Risk of Later Aneurysm Rupture.

PubMed

Cheng, Lik Fai; Cheung, Kwok Fai; Chan, Kwong Man; Ma, Johnny Ka Fai; Luk, Wing Hang; Chan, Micah Chi King; Ng, Carol Wing Kei; Mahboobani, Neeraj Ramesh; Ng, Wai Kin; Wong, Ting

2016-11-01

Nellix Endovascular Aneurysm Sealing (EVAS) system is a new concept and technology of abdominal aortic aneurysm (AAA) repair. Elective EVAS using Nellix device was performed for a 83-year-old man with AAA. 2-month post-EVAS CTA surveillance demonstrated mild enlargement of aneurysmal sac and separation of the EndoBags, but without detectable endoleak. The patient developed sudden AAA rupture with retroperitoneal hematoma at about 4 months after EVAS. We postulated that early enlargement of aneurysmal sac and separation of EndoBags of Nellix devices after EVAS, even without detectable endoleak, might indicate significant aneurysmal wall weakening with increased risk of later AAA rupture. To the best of the authors' knowledge, this was the first reported case of aortic rupture after EVAS without detectable endoleak during and after the procedure.

Enhanced Adhesion of EVA Laminates to Primed Glass Substrates Subjected to Damp-Heat Exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F. J.; Jorgensen, G. J.

2005-02-01

We investigated the effectiveness of glass-surface priming to promote enhanced adhesion of EVA laminates during damp-heat exposure at 85 C and 85% relative humidity. The primary objective was to develop advanced encapsulant formulations by incorporation of various primer formulations that exhibit improved adhesion during damp-heat exposure. Several primer formulations were identified that greatly enhanced the EVA adhesion strength, including to the extent that peeling could not be initiated, even for the laminates of the glass substrate/fast-cure EVA15295P/TPE backsheet (a Tedlar/polyester/EVA tri-laminate) that were exposed in a damp-heat test chamber for more than 750 h. The results show that a synergisticmore » increase in the interfacial hydrophobicity, siloxane density, and cross-linking density are the key attributes to the improvement in the EVA adhesion strength.« less

A generic assay for whole-genome amplification and deep sequencing of enterovirus A71

PubMed Central

Tan, Le Van; Tuyen, Nguyen Thi Kim; Thanh, Tran Tan; Ngan, Tran Thuy; Van, Hoang Minh Tu; Sabanathan, Saraswathy; Van, Tran Thi My; Thanh, Le Thi My; Nguyet, Lam Anh; Geoghegan, Jemma L.; Ong, Kien Chai; Perera, David; Hang, Vu Thi Ty; Ny, Nguyen Thi Han; Anh, Nguyen To; Ha, Do Quang; Qui, Phan Tu; Viet, Do Chau; Tuan, Ha Manh; Wong, Kum Thong; Holmes, Edward C.; Chau, Nguyen Van Vinh; Thwaites, Guy; van Doorn, H. Rogier

2015-01-01

Enterovirus A71 (EV-A71) has emerged as the most important cause of large outbreaks of severe and sometimes fatal hand, foot and mouth disease (HFMD) across the Asia-Pacific region. EV-A71 outbreaks have been associated with (sub)genogroup switches, sometimes accompanied by recombination events. Understanding EV-A71 population dynamics is therefore essential for understanding this emerging infection, and may provide pivotal information for vaccine development. Despite the public health burden of EV-A71, relatively few EV-A71 complete-genome sequences are available for analysis and from limited geographical localities. The availability of an efficient procedure for whole-genome sequencing would stimulate effort to generate more viral sequence data. Herein, we report for the first time the development of a next-generation sequencing based protocol for whole-genome sequencing of EV-A71 directly from clinical specimens. We were able to sequence viruses of subgenogroup C4 and B5, while RNA from culture materials of diverse EV-A71 subgenogroups belonging to both genogroup B and C was successfully amplified. The nature of intra-host genetic diversity was explored in 22 clinical samples, revealing 107 positions carrying minor variants (ranging from 0 to 15 variants per sample). Our analysis of EV-A71 strains sampled in 2013 showed that they all belonged to subgenogroup B5, representing the first report of this subgenogroup in Vietnam. In conclusion, we have successfully developed a high-throughput next-generation sequencing-based assay for whole-genome sequencing of EV-A71 from clinical samples. PMID:25704598

Ethylene-vinyl acetate foam as a new lung substitute in radiotherapy.

PubMed

Marqués, Enrique; Mancha, Pedro J

2018-04-01

The purpose of this study was to evaluate ethylene-vinyl acetate (EVA) foam as a new lung substitute in radiotherapy and to study its physical and dosimetric characteristics. We calculated the ideal vinyl acetate (VA) content of EVA foam sheets to mimic the physical and dosimetric characteristics of the ICRU lung tissue. We also computed the water-to-medium mass collision stopping power ratios, mass attenuation coefficients, CT numbers, effective atomic numbers and electron densities for: ICRU lung tissue, the RANDO commercial phantom, scaled WATER and EVA foam sheets with varying VA contents in a range between the minimum and maximum values supplied by the manufacturer. For all these substitutes, we simulated percent depth-dose curves with EGSnrc Monte Carlo (MC PDDs) in a water-lung substitute-water slab phantom expressed as dose-to-medium and dose-to-water for 3 × 3- and 10 × 10-cm 2 field sizes. PDD for the 10 × 10-cm 2 field size was also calculated with the MultiGrid Superposition algorithm (MGS PDD) for a relative electron density to water ratio of 0.26. The latter was compared with the MC PDDs in dose-to-water for scaled WATER and EVA foam sheets with the VA content that was most similar to the calculated ideal content that is physically achievable in practice. We calculated an ideal VA content of 55%; however, the maximum physically achievable content with current manufacturing techniques is 40%. The physical characteristics of the EVA foam sheets with a VA content of 40% (EVA40) are very close to those of the ICRU lung reference. The physical densities of the EVA40 foam sheets ranged from 0.030 to 0.965 g/cm 3 , almost covering the entire physical density range of the inflated/deflated lung (0.260-1.050 g/cm 3 ). Its mass attenuation coefficient at the effective energy of a 6-MV photon beam agrees within 0.8% of the ICRU reference value, and its CT number agrees within 6 HU. The effective atomic number for EVA40 varies by less than 0.42 of the ICRU value, and its effective electron density is within 0.9%. PDDs expressed in dose-to-medium and dose-to-water agree with the ICRU curve within 2% in all regions. PDDs calculated with both MC and MGS were within 1.5%. The EVA40 is an excellent cork-like lung substitute for radiotherapy applications. From a sole material used in footwear, it is possible to obtain a lung substitute that mimics the physical and dosimetric characteristics of ICRU lung tissue even better than the RANDO commercial phantom. © 2018 American Association of Physicists in Medicine.

Investigation of the effects of Extra Vehicular Activity (EVA) and Launch and Entry (LES) gloves on performance

NASA Technical Reports Server (NTRS)

Bishu, Ram R.

1992-01-01

Human capabilities such as dexterity, manipulability, and tactile perception are unique and render the hand as a very versatile, effective and a multipurpose tool. This is especially true for unknown environments such as the EVA environment. In the microgravity environment interfaces, procedures, and activities are too complex, diverse, and defy advance definition. Under these conditions the hand becomes the primary means of locomotion, restraint, and material handling. Facilitation of these activities, with simultaneous protection from the cruel EVA environment are the two, often conflicting, objectives of glove design. The objectives of this study was (1) to assess the effects of EVA gloves at different pressures on human hand capabilities, (2) to devise a protocol for evaluating EVA gloves, (3) to develop force time relations for a number of EVA glove pressure combinations, and (4) to evaluate two types of launch and entry suit gloves. The objectives were achieved through three experiments. The experiments for achieving objectives 1, 2, and 3 were performed in the glove box in building 34. In experiment 1 three types of EVA gloves were tested at five pressure differentials. A number of performance measures were recorded. In experiment 2 the same gloves as in experiment 1 were evaluated in a reduced number of pressure conditions. The performance measure was endurance time. Six subjects participated in both the experiments. In experiment 3 two types of launch and entry suit gloves were evaluated using a paradigm similar to experiment 1. Currently the data is being analyzed. However for this report some summary analyses have been performed. The results indicate that a) With EVA gloves strength is reduced by nearly 50 percent, b) performance decrements increase with increasing pressure differential, c) TMG effects are not consistent across the three gloves tested, d) some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand, and e) differences in performance exist between partial pressure suit glove and full pressure suit glove, especially in the unpressurized condition.

Suited crewmember productivity

NASA Astrophysics Data System (ADS)

Barer, A. S.; Filipenkov, S. N.

Analysis of the extravehicular activity (EVA) sortie experience gained in the former Soviet Union and physiologic hygienic aspect of space suit design and development shows that crewmember productivity is related to the following main factors: —space suit microclimate (gas composition, pressure and temperature); —limitation of motion activity and perception, imposed by the space suit; —good crewmember training in the ground training program; —level of crewmember general physical performance capabilities in connection with mission duration and intervals between sorties; —individual EVA experience (with accumulation) at which workmanship improves, while metabolism, physical and emotional stress decreases; —concrete EVA duration and work rate; —EVA bioengineering, including selection of tools, work station, EVA technology and mechanization.

Flaxseed Mitigates Acute Oxidative Lung Damage in a Mouse Model of Repeated Radiation and Hyperoxia Exposure Associated with Space Exploration.

PubMed

Pietrofesa, Ralph A; Solomides, Charalambos C; Christofidou-Solomidou, Melpo

Spaceflight missions may require crewmembers to conduct extravehicular activities (EVA). Pre-breathe protocols in preparation for an EVA entail 100% hyperoxia exposure that may last for a few hours and be repeated 2-3 times weekly. Each EVA is associated with additional challenges such as low levels of total body cosmic/galactic radiation exposure that may present a threat to crewmember health. We have developed a mouse model of total body radiation and hyperoxia exposure and identified acute damage of lung tissues. In the current study we evaluated the usefulness of dietary flaxseed (FS) as a countermeasure agent for such double-hit exposures. We evaluated lung tissue changes 2 weeks post-initiation of exposure challenges. Mouse cohorts (n=5/group) were pre-fed diets containing either 0% FS or 10% FS for 3 weeks and exposed to: a) normoxia (Untreated); b) >95% O 2 (O 2 ); c) 0.25Gy single fraction gamma radiation (IR); or d) a combination of O 2 and IR (O 2 +IR) 3 times per week for 2 consecutive weeks, where 8-hour hyperoxia treatments were spanned by normoxic intervals. At 2 weeks post challenge, while control-diet fed mice developed significant lung injury and inflammation across all challenges, FS protected lung tissues by decreasing bronchoalveolar lavage fluid (BALF) neutrophils (p<0.003) and protein levels, oxidative tissue damage, as determined by levels of malondialdehyde (MDA) (p<0.008) and nitrosative stress as determined by nitrite levels. Lung hydroxyproline levels, a measure of lung fibrosis, were significantly elevated in mice fed 0% FS (p<0.01) and exposed to hyperoxia/radiation or the combination treatment, but not in FS-fed mice. FS also decreased levels of a pro-inflammatory, pro-fibrogenic cytokine (TGF-β1) gene expression levels in lung. Flaxseed mitigated adverse effects in lung of repeat exposures to radiation/hyperoxia. This data will provide useful information in the design of countermeasures to early tissue oxidative damage associated with space exploration.

Flaxseed Mitigates Acute Oxidative Lung Damage in a Mouse Model of Repeated Radiation and Hyperoxia Exposure Associated with Space Exploration

PubMed Central

Pietrofesa, Ralph A.; Solomides, Charalambos C.; Christofidou-Solomidou, Melpo

2015-01-01

Background Spaceflight missions may require crewmembers to conduct extravehicular activities (EVA). Pre-breathe protocols in preparation for an EVA entail 100% hyperoxia exposure that may last for a few hours and be repeated 2-3 times weekly. Each EVA is associated with additional challenges such as low levels of total body cosmic/galactic radiation exposure that may present a threat to crewmember health. We have developed a mouse model of total body radiation and hyperoxia exposure and identified acute damage of lung tissues. In the current study we evaluated the usefulness of dietary flaxseed (FS) as a countermeasure agent for such double-hit exposures. Methods We evaluated lung tissue changes 2 weeks post-initiation of exposure challenges. Mouse cohorts (n=5/group) were pre-fed diets containing either 0% FS or 10% FS for 3 weeks and exposed to: a) normoxia (Untreated); b) >95% O2 (O2); c) 0.25Gy single fraction gamma radiation (IR); or d) a combination of O2 and IR (O2+IR) 3 times per week for 2 consecutive weeks, where 8-hour hyperoxia treatments were spanned by normoxic intervals. Results At 2 weeks post challenge, while control-diet fed mice developed significant lung injury and inflammation across all challenges, FS protected lung tissues by decreasing bronchoalveolar lavage fluid (BALF) neutrophils (p<0.003) and protein levels, oxidative tissue damage, as determined by levels of malondialdehyde (MDA) (p<0.008) and nitrosative stress as determined by nitrite levels. Lung hydroxyproline levels, a measure of lung fibrosis, were significantly elevated in mice fed 0% FS (p<0.01) and exposed to hyperoxia/radiation or the combination treatment, but not in FS-fed mice. FS also decreased levels of a pro-inflammatory, pro-fibrogenic cytokine (TGF-β1) gene expression levels in lung. Conclusion Flaxseed mitigated adverse effects in lung of repeat exposures to radiation/hyperoxia. This data will provide useful information in the design of countermeasures to early tissue oxidative damage associated with space exploration. PMID:25705570

Does hard insertion and space improve shock absorption ability of mouthguard?

PubMed

Takeda, Tomotaka; Ishigami, Keiichi; Handa, Jun; Naitoh, Kaoru; Kurokawa, Katsuhide; Shibusawa, Mami; Nakajima, Kazunori; Kawamura, Shintaro

2006-04-01

Mouthguards are expected to reduce sports-related orofacial injuries. Numerous studies have been conduced to improve the shock absorption ability of mouthguards using air cells, sorbothane, metal wire, or hard material insertion. Most of these were shown to be effective; however, the result of each study has not been applied to clinical use. The aim of this study was to develop mouthguards that have sufficient prevention ability and ease of clinical application with focus on a hard insertion and space. Ethylene vinyl acetate (EVA) mouthguard blank used was Drufosoft and the acrylic resin was Biolon (Dreve-Dentamid GMBH, Unna, Germany). Three types of mouthguard samples tested were constructed by means of a Dreve Drufomat (Type SO, Dreve-Dentamid) air pressure machine: the first was a conventional laminated type of EVA mouthguard material; the second was a three layer type with acrylic resin inner layer (hard-insertion); the third was the same as the second but with space that does not come into contact with tooth surfaces (hard + space). As a control, without any mouthguard condition (NOMG) was measured. A pendulum type impact testing machine with interchangeable impact object (steel ball and baseball) and dental study model (D17FE-NC.7PS, Nissin, Tokyo, Japan) with the strain gages (KFG-1-120-D171-11N30C2: Kyowa, Tokyo, Japan) applied to teeth and the accelerometer to the dentition (AS-A YG-2768 100G, Kyowa) were used to measure transmitted forces. Statistical analysis (anova, P < 0.01) showed significant differences among four conditions of NOMG and three different mouthguards in both objects and sensor. About acceleration: in a steel ball which was a harder impact object, shock absorption ability of about 40% was shown with conventional EVA and hard-insertion and about 50% with hard + space. In a baseball that was softer compared with steel ball, a decrease rate is smaller, reduction (EVA = approximately 4%, hard-insertion = approximately 12%, hard + space = approximately 25%) was admitted in the similar order. A significant difference was found with all the combinations except for between EVA and hard-insertion with steel ball (Tukey test). About distortion: both buccal and lingual, distortions had become small in order of EVA, hard-insertion, and hard + space, too. The decrease rate is larger than acceleration, EVA = approximately 47%, hard-insertion = 80% or more, and hard +space = approximately 98%, in steel ball. EVA = approximately 30%, hard-insertion = approximately 75%, and hard + space = approximately 98% in baseball. And a significant difference was found with all the combinations (Tukey test). Especially, hard + space has decreased the distortion of teeth up to several percentages. Acceleration of the maxilla and distortions of the tooth became significantly smaller when wearing any type of mouthguard, in both impact objects. But the effect of mouthguard was clearer in the distortion of the tooth and with steel ball. Considering the differences of mouthguards, the hard-insertion and the hard + space had significantly greater buffer capacity than conventional EVA. Furthermore, hard + space shows quite high shock absorption ability in the tooth distortion. Namely, hard + space has decreased the distortion of teeth up to several percentages in both impact objects.

Information requirements and methodology for development of an EVA crewmember's heads up display

NASA Astrophysics Data System (ADS)

Petrek, J. S.

This paper presents a systematic approach for developing a Heads Up Display (HUD) to be used within the helmet of the Extra Vehicular Activity (EVA) crewmember. The information displayed on the EVA HUD will be analogous to EVA Flight Data File (FDF) information, which is an integral part of NASA's current Space Transportation System. Another objective is to determine information requirements and media techniques ultimately leading to the helmet-mounted HUD presentation technique.

The main results of EVA medical support on the Mir Space Station

NASA Astrophysics Data System (ADS)

Katuntsev, V. P.; Osipov, Yu. Yu.; Barer, A. S.; Gnoevaya, N. K.; Tarasenkov, G. G.

2004-04-01

The aim of this paper is to review the main results of medical support of 78 two-person extravehicular activities (EVAs) which have been conducted in the Mir Space Program. Thirty-six male crewmembers participated in these EVAs. Maximum length of a space walk was equal to 7 h 14 min. The total duration of all space walks reached 717.1 man-hours. The maximum frequency of EVA's execution was 10 per year. Most of the EVAs (67) have been performed at mission elapsed time ranging from 31 to 180 days. The oxygen atmosphere of the Orlan space suit with a pressure of 40 kPa in combination with the normobaric cabin environment and a short (30 min) oxygen prebreathe protocol have minimized the risk of decompression sickness (DCS). There has been no incidence of DCS during performed EVAs. At the peak activity, metabolic rates and heart rates increased up to 9.9- 13 kcal/ min and 150- 174 min-1, respectively. The medical problems have centred on feeling of moderate overcooling during a rest period in a shadow after the high physical loads, episodes with tachycardia accompanied by cardiac rhythm disorders at the moments of emotional stress, pains in the muscles and general fatigue after the end of a hard EVA. All of the EVAs have been completed safely.

The main results of EVA medical support on the Mir Space Station.

PubMed

Katuntsev, V P; Osipov, Yu Yu; Barer, A S; Gnoevaya, N K; Tarasenkov, G G

2004-04-01

The aim of this paper is to review the main results of medical support of 78 two-person extravehicular activities (EVAs) which have been conducted in the Mir Space Program. Thirty-six male crewmembers participated in these EVAs. Maximum length of a space walk was equal to 7 h 14 min. The total duration of all space walks reached 717.1 man-hours. The maximum frequency of EVA's execution was 10 per year. Most of the EVAs (67) have been performed at mission elapsed time ranging from 31 to 180 days. The oxygen atmosphere of the Orlan space suit with a pressure of 40 kPa in combination with the normobaric cabin environment and a short (30 min) oxygen prebreathe protocol have minimized the risk of decompression sickness (DCS). There has been no incidence of DCS during performed EVAs. At the peak activity, metabolic rates and heart rates increased up to 9.9-13 kcal/min and 150-174 min-1, respectively. The medical problems have centred on feeling of moderate overcooling during a rest period in a shadow after the high physical loads, episodes with tachycardia accompanied by cardiac rhythm disorders at the moments of emotional stress, pains in the muscles and general fatigue after the end of a hard EVA. All of the EVAs have been completed safely. c2003 Elsevier Ltd. All rights reserved.

Payload bay activity during second EVA of STS-72 mission

NASA Image and Video Library

1996-01-16

STS072-393-008 (17 Jan. 1996) --- Astronaut Leroy Chiao gives a thumbs up signal, marking the success of his second extravehicular activity (EVA) in three days. Chiao was joined by astronaut Winston E. Scott on this EVA.

Shkaplerov works with EVA Hardware in the SM

NASA Image and Video Library

2012-02-03

ISS030-E-061158 (3 Feb. 2012) --- Russian cosmonaut Oleg Kononenko, Expedition 30 flight engineer, works with extravehicular activity (EVA) hardware in the Zvezda Service Module of the International Space Station in preparation for an EVA scheduled for Feb. 16, 2012.

Shkaplerov works with EVA Hardware in the SM

NASA Image and Video Library

2012-02-03

ISS030-E-061157 (3 Feb. 2012) --- Russian cosmonaut Anton Shkaplerov, Expedition 30 flight engineer, works with extravehicular activity (EVA) hardware in the Zvezda Service Module of the International Space Station in preparation for an EVA scheduled for Feb. 16, 2012.

The Exercise and Environmental Physiology of Extravehicular Activity

NASA Technical Reports Server (NTRS)

Cowell, S. A.; Stocks, J. M.; Evans, D. G.; Simonson, S. R.; Greenleaf, J. E.; Dalton, Bonnie P. (Technical Monitor)

2000-01-01

Over the history of human expansion into space, extravehicular activity (EVA) has become indispensable for both daily living in weightlessness and for further space exploration. The physiological factors involved in the performance of extensive EVA, necessary for construction and maintenance of the International Space Station and during future human interplanetary missions, require further examination. An understanding of the physiological aspects of exercise and thermoregulation in the EVA environment will help to insure the health, safety, and efficiency of working astronauts. To that end, this review will focus on the interaction of the exercise and environmental aspects of EVA, as well as exercise during spaceflight and ground-based simulations such as bed-rest deconditioning. It will examine inflight exercise thermoregulation, and exercise, muscular strength, supine vs. seated exercise, exercise thermoregulation, and exercise in a hypobaric environment. Due to the paucity of data from controlled human research in this area, it is clear that more scientific studies are needed to insure safe and efficient extravehicular activity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karina, Wiwiek, E-mail: wiekarina@gmail.com; Heraldy, Eddy, E-mail: eheraldy@gmail.com; Pramono, Edi

Ca-Mg-Al hydrotalcite-like compound (Ca-Mg-Al HTlc) was prepared by co-precipitation method using brine water that is well known as the desalination process waste water. The structure of Ca-Mg-Al HTlc was determined by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. Ca-Mg-Al HTlc was studied as a non-halogenated filler in ethylene vinyl acetate (EVA) matrix. Composites with different filler concentrations were prepared to evaluate the influence of Ca-Mg-Al HTlc on thermal and mechanical properties of EVA.The presence of Ca-Mg-Al HTlc in the composite has been confirmed by FTIR analysis. Thermal properties of composites show significant reduction of degradation temperature as wellmore » as the loading of HTlc in EVA. However, the total enthalpies combustion of composites with 1% and 5% HTlc loadings higher compared to neat EVA. Further, mechanical properties were determined by tensile test. The result shows that tensile strength and elongation at break of composites decrease relatively by Ca-Mg-Al HTlc addition.« less

Modified Advanced Crew Escape Suit Intravehicular Activity Suit for Extravehicular Activity Mobility Evaluations

NASA Technical Reports Server (NTRS)

Watson, Richard D.

2014-01-01

The use of an intravehicular activity (IVA) suit for a spacewalk or extravehicular activity (EVA) was evaluated for mobility and usability in the Neutral Buoyancy Laboratory (NBL) environment at the Sonny Carter Training Facility near NASA Johnson Space Center in Houston, Texas. The Space Shuttle Advanced Crew Escape Suit was modified to integrate with the Orion spacecraft. The first several missions of the Orion Multi-Purpose Crew Vehicle will not have mass available to carry an EVA-specific suit; therefore, any EVA required will have to be performed by the Modified Advanced Crew Escape Suit (MACES). Since the MACES was not designed with EVA in mind, it was unknown what mobility the suit would be able to provide for an EVA or whether a person could perform useful tasks for an extended time inside the pressurized suit. The suit was evaluated in multiple NBL runs by a variety of subjects, including crewmembers with significant EVA experience. Various functional mobility tasks performed included: translation, body positioning, tool carrying, body stabilization, equipment handling, and tool usage. Hardware configurations included with and without Thermal Micrometeoroid Garment, suit with IVA gloves and suit with EVA gloves. Most tasks were completed on International Space Station mock-ups with existing EVA tools. Some limited tasks were completed with prototype tools on a simulated rocky surface. Major findings include: demonstrating the ability to weigh-out the suit, understanding the need to have subjects perform multiple runs prior to getting feedback, determining critical sizing factors, and need for adjusting suit work envelope. Early testing demonstrated the feasibility of EVA's limited duration and limited scope. Further testing is required with more flight-like tasking and constraints to validate these early results. If the suit is used for EVA, it will require mission-specific modifications for umbilical management or Primary Life Support System integration, safety tether attachment, and tool interfaces. These evaluations are continuing through calendar year 2014.

An Alternative Approach to Human Servicing of Crewed Earth Orbiting Spacecraft

NASA Technical Reports Server (NTRS)

Mularski, John R.; Alpert, Brian K.

2017-01-01

As crewed spacecraft have grown larger and more complex, they have come to rely on spacewalks, or Extravehicular Activities (EVA), for mission success and crew safety. Typically, these spacecraft maintain all of the hardware and trained personnel needed to perform an EVA on-board at all times. Maintaining this capability requires volume and up-mass for storage of EVA hardware, crew time for ground and on-orbit training, and on-orbit maintenance of EVA hardware. This paper proposes an alternative methodology, utilizing launch on-need hardware and crew to provide EVA capability for space stations in Earth orbit after assembly complete, in the same way that one would call a repairman to fix something at their home. This approach would reduce ground training requirements, save Intravehicular Activity (IVA) crew time in the form of EVA hardware maintenance and on-orbit training, and lead to more efficient EVAs because they would be performed by specialists with detailed knowledge and training stemming from their direct involvement in the development of the EVA. The on-orbit crew would then be available to focus on the immediate response to the failure as well as the day-to-day operations of the spacecraft and payloads. This paper will look at how current unplanned EVAs are conducted, including the time required for preparation, and offer alternatives for future spacecraft. As this methodology relies on the on-time and on-need launch of spacecraft, any space station that utilized this approach would need a robust transportation system including more than one launch vehicle capable of carrying crew. In addition, the fault tolerance of the space station would be an important consideration in how much time was available for EVA preparation after the failure. Each future program would have to weigh the risk of on-time launch against the increase in available crew time for the main objective of the spacecraft.

An Alternative Approach to Human Servicing of Manned Earth Orbiting Spacecraft

NASA Technical Reports Server (NTRS)

Mularski, John; Alpert, Brian

2011-01-01

As manned spacecraft have grown larger and more complex, they have come to rely on spacewalks or Extravehicular Activities (EVA) for both mission success and crew safety. Typically these spacecraft maintain all of the hardware and trained personnel needed to perform an EVA on-board at all times. Maintaining this capability requires volume and up-mass for storage of EVA hardware, crew time for ground and on-orbit training, and on-orbit maintenance of EVA hardware . This paper proposes an alternative methodology to utilize launch-on-need hardware and crew to provide EVA capability for space stations in Earth orbit after assembly complete, in the same way that most people would call a repairman to fix something at their home. This approach would not only reduce ground training requirements and save Intravehicular Activity (IVA) crew time in the form of EVA hardware maintenance and on-orbit training, but would also lead to more efficient EVAs because they would be performed by specialists with detailed knowledge and training stemming from their direct involvement in the development of the EVA. The on-orbit crew would then be available to focus on the immediate response to the failure as well as the day-to-day operations of the spacecraft and payloads. This paper will look at how current ISS unplanned EVAs are conducted, including the time required for preparation, and offer alternatives for future spacecraft utilizing lessons learned from ISS. As this methodology relies entirely on the on-time and on-need launch of spacecraft, any space station that utilized this approach would need a robust transportation system including more than one launch vehicle capable of carrying crew. In addition the fault tolerance of the space station would be an important consideration in how much time was available for EVA preparation after the failure. Each future program would have to weigh the risk of on-time launch against the increase in available crew time for the main objective of the spacecraft.

EVA assembly of large space structure element

NASA Technical Reports Server (NTRS)

Bement, L. J.; Bush, H. G.; Heard, W. L., Jr.; Stokes, J. W., Jr.

1981-01-01

The results of a test program to assess the potential of manned extravehicular activity (EVA) assembly of erectable space trusses are described. Seventeen tests were conducted in which six "space-weight" columns were assembled into a regular tetrahedral cell by a team of two "space"-suited test subjects. This cell represents the fundamental "element" of a tetrahedral truss structure. The tests were conducted under simulated zero-gravity conditions. Both manual and simulated remote manipulator system modes were evaluated. Articulation limits of the pressure suit and zero gravity could be accommodated by work stations with foot restraints. The results of this study have confirmed that astronaut EVA assembly of large, erectable space structures is well within man's capabilities.

Determination of the linear coefficient of thermal expansion in polymer films at the nanoscale: influence of the composition of EVA copolymers and the molecular weight of PMMA.

PubMed

González-Benito, J; Castillo, E; Cruz-Caldito, J F

2015-07-28

Nanothermal-expansion of poly(ethylene-co-vinylacetate), EVA, and poly(methyl methacrylate), PMMA, in the form of films was measured to finally obtain linear coefficients of thermal expansion, CTEs. The simple deflection of a cantilever in an atomic force microscope, AFM, was used to monitor thermal expansions at the nanoscale. The influences of: (a) the structure of EVA in terms of its composition (vinylacetate content) and (b) the size of PMMA chains in terms of the molecular weight were studied. To carry out this, several polymer samples were used, EVA copolymers with different weight percents of the vinylacetate comonomer (12, 18, 25 and 40%) and PMMA polymers with different weight average molecular weights (33.9, 64.8, 75.600 and 360.0 kg mol(-1)). The dependencies of the vinyl acetate weight fraction of EVA and the molecular weight of PMMA on their corresponding CTEs were analyzed to finally explain them using new, intuitive and very simple models based on the rule of mixtures. In the case of EVA copolymers a simple equation considering the weighted contributions of each comonomer was enough to estimate the final CTE above the glass transition temperature. On the other hand, when the molecular weight dependence is considered the free volume concept was used as novelty. The expansion of PMMA, at least at the nanoscale, was well and easily described by the sum of the weighted contributions of the occupied and free volumes, respectively.

Astronaut Ronald Evans photographed during transearth coast EVA

NASA Technical Reports Server (NTRS)

1972-01-01

Astronaut Ronald E. Evans is photographed performing extravehicular activity (EVA) during the Apollo 17 spacecraft's transearth coast. During his EVA Command Module pilot Evans retrieved film cassettes from the Lunar Sounder, Mapping Camera, and Panoramic Camera. The total time for the transearth EVA was one hour seven minutes 19 seconds, starting at ground elapsed time of 257:25 (2:28 p.m.) amd ending at ground elapsed time of 258:42 (3:35 p.m.) on Sunday, December 17, 1972.

The development of a test methodology for the evaluation of EVA gloves

NASA Technical Reports Server (NTRS)

O'Hara, John M.; Cleland, John; Winfield, Dan

1988-01-01

This paper describes the development of a standardized set of tests designed to assess EVA-gloved hand capabilities in six measurement domains: range of motion, strength, tactile perception, dexterity, fatigue, and comfort. Based upon an assessment of general human-hand functioning and EVA task requirements, several tests within each measurement domain were developed to provide a comprehensive evaluation. All tests were designed to be conducted in a glove box with the bare hand as a baseline and the EVA glove at operating pressure.

Helms during EVA on the ISS

NASA Image and Video Library

2001-04-06

STS102-325-023 (11 March 2001) --- Astronaut Susan J. Helms completes a scheduled space walk task on the International Space Station (ISS). This extravehicular activity (EVA), on which Helms was joined by astronaut James S. Voss (out of frame), was the first of two scheduled STS-102 EVA sessions. The pair, destined to become members of the Expedition Two crew aboard the station later in the mission, rode aboard Discovery into orbit and at the time of this EVA were still regarded as STS-102 mission specialists.

Metabolic assessments during extra-vehicular activity.

PubMed

Osipov YuYu; Spichkov, A N; Filipenkov, S N

1998-01-01

Extra-vehicular activity (EVA) has a significant role during extended space flights. It demonstrates that humans can survive and perform useful work outside the Orbital Space Stations (OSS) while wearing protective space suits (SS). When the International Space Station 'Alpha' (ISSA) is fully operational, EVA assembly, installation, maintenance and repair operations will become an everyday repetitive work activity in space. It needs new ergonomic evaluation of the work/rest schedule for an increasing of the labor amount per EVA hour. The metabolism assessment is a helpful method to control the productivity of the EVA astronaut and to optimize the work/rest regime. Three following methods were used in Russia to estimate real-time metabolic rates during EVA: 1. Oxygen consumption, computed from the pressure drop in a high pressure bottle per unit time (with actual thermodynamic oxygen properties under high pressure and oxygen leakage taken into account). 2. Carbon dioxide production, computed from CO2 concentration at the contaminant control cartridge and gas flow rate in the life support subsystem closed loop (nominal mode) or gas leakage in the SS open loop (emergency mode). 3. Heat removal, computed from the difference between the temperatures of coolant water or gas and its flow rate in a unit of time (with assumed humidity and wet oxygen state taken into account). Comparison of heat removal values with metabolic rates enables us to determine the thermal balance during an operative medical control of EVA at "Salyut-6", "Salyut-7" and "Mir" OSS. Complex analysis of metabolism, body temperature and heat rate supports a differential diagnosis between emotional and thermal components of stress during EVA. It gives a prognosis of human homeostasis during EVA. Available information has been acquired into an EVA data base which is an effective tool for ergonomical optimization.

Metabolic assessments during extra-vehicular activity

NASA Astrophysics Data System (ADS)

Osipov, Yu. Yu.; Spichkov, A. N.; Filipenkov, S. N.

Extra-vehicular activity (EVA) has a significant role during extended space flights. It demonstrates that humans can survive and perform useful work outside the Orbital Space Stations (OSS) while wearing protective space suits (SS). When the International Space Station 'Alpha'(ISSA) is fully operational, EVA assembly, installation, maintenance and repair operations will become an everyday repetitive work activity in space. It needs new ergonomic evaluation of the work/rest schedule for an increasing of the labor amount per EVA hour. The metabolism assessment is a helpful method to control the productivity of the EVA astronaut and to optimize the work/rest regime. Three following methods were used in Russia to estimate real-time metabolic rates during EVA: 1. Oxygen consumption, computed from the pressure drop in a high pressure bottle per unit time (with actual thermodynamic oxygen properties under high pressure and oxygen leakage taken into account). 2. Carbon dioxide production, computed from CO 2 concentration at the contaminant control cartridge and gas flow rate in the life support subsystem closed loop (nominal mode) or gas leakage in the SS open loop (emergency mode). 3. Heat removal, computed from the difference between the temperatures of coolant water or gas and its flow rate in a unit of time (with assumed humidity and wet oxygen state taken into account). Comparison of heat removal values with metabolic rates enables us to determine the thermal balance during an operative medical control of EVA at "Salyut-6", "Salyut-7" and "Mir" OSS. Complex analysis of metabolism, body temperature and heat rate supports a differential diagnosis between emotional and thermal components of stress during EVA. It gives a prognosis of human homeostasis during EVA. Available information has been acquired into an EVA data base which is an effective tool for ergonomical optimization.

Shoulder Injuries in US Astronauts Related to EVA Suit Design

NASA Technical Reports Server (NTRS)

Scheuring, R. A.; McCulloch, P.; Van Baalen, Mary; Minard, Charles; Watson, Richard; Blatt, T.

2011-01-01

Introduction: For every one hour spent performing extravehicular activity (EVA) in space, astronauts in the US space program spend approximately six to ten hours training in the EVA spacesuit at NASA-Johnson Space Center's Neutral Buoyancy Lab (NBL). In 1997, NASA introduced the planar hard upper torso (HUT) EVA spacesuit which subsequently replaced the existing pivoted HUT. An extra joint in the pivoted shoulder allows increased mobility but also increased complexity. Over the next decade a number of astronauts developed shoulder problems requiring surgical intervention, many of whom performed EVA training in the NBL. This study investigated whether changing HUT designs led to shoulder injuries requiring surgical repair. Methods: US astronaut EVA training data and spacesuit design employed were analyzed from the NBL data. Shoulder surgery data was acquired from the medical record database, and causal mechanisms were obtained from personal interviews Analysis of the individual HUT designs was performed as it related to normal shoulder biomechanics. Results: To date, 23 US astronauts have required 25 shoulder surgeries. Approximately 48% (11/23) directly attributed their injury to training in the planar HUT, whereas none attributed their injury to training in the pivoted HUT. The planar HUT design limits shoulder abduction to 90 degrees compared to approximately 120 degrees in the pivoted HUT. The planar HUT also forces the shoulder into a forward flexed position requiring active retraction and extension to increase abduction beyond 90 degrees. Discussion: Multiple factors are associated with mechanisms leading to shoulder injury requiring surgical repair. Limitations to normal shoulder mechanics, suit fit, donning/doffing, body position, pre-existing injury, tool weight and configuration, age, in-suit activity, and HUT design have all been identified as potential sources of injury. Conclusion: Crewmembers with pre-existing or current shoulder injuries or certain anthropometric body types should conduct NBL EVA training in the pivoted HUT.

New monitoring by thermogravimetry for radiation degradation of EVA

NASA Astrophysics Data System (ADS)

Boguski, J.; Przybytniak, G.; Łyczko, K.

2014-07-01

The radiation ageing of ethylene vinyl-acetate copolymer (EVA) as the jacket of cable applied in nuclear power plant was carried out by gamma rays irradiation, and the degradation was monitored by a thermo-gravimetric analysis (TGA). The EVA decomposition rate in air by the isothermal at 400 °C decreased with increase of dose and also with decrease of the dose rate. The behavior of EVA jacket of cable indicated that the decomposition rate at 400 °C was reduced with increase of oxidation. The elongation at break by tensile test for the radiation aged EVA was closely related to the decomposition rate at 400 °C; therefore, the TGA might be applied for a diagnostic technique of the cable degradation.

Extravehicular Activity (EVA) 101: Constellation EVA Systems

NASA Technical Reports Server (NTRS)

Jordan, Nicole C.

2007-01-01

A viewgraph presentation on Extravehicular Activity (EVA) Systems is shown. The topics include: 1) Why do we need space suits? 2) Protection From the Environment; 3) Primary Life Support System (PLSS); 4) Thermal Control; 5) Communications; 6) Helmet and Extravehicular Visor Assy; 7) Hard Upper Torso (HUT) and Arm Assy; 8) Display and Controls Module (DCM); 9) Gloves; 10) Lower Torso Assembly (LTA); 11) What Size Do You Need?; 12) Boot and Sizing Insert; 13) Boot Heel Clip and Foot Restraint; 14) Advanced and Crew Escape Suit; 15) Nominal & Off-Nominal Landing; 16) Gemini Program (mid-1960s); 17) Apollo EVA on Service Module; 18) A Bold Vision for Space Exploration, Authorized by Congress; 19) EVA System Missions; 20) Configurations; 21) Reduced Gravity Program; and 22) Other Opportunities.

Fogging Control on LDPE/EVA Coextruded Films: Wettability Behavior and Its Correlation with Electric Performance.

PubMed

Waldo-Mendoza, Miguel A; Quiñones-Jurado, Zoe V; Pérez-Medina, Juan C; Yañez-Soto, Bernardo; Ramírez-González, Pedro E

2017-02-22

The transformation of fog at a non-visible water layer on a membrane of low-density polyethylene (LDPE) and ethylene-vinyl acetate (EVA) was evaluated. Nonionic surfactants of major demand in the polyolefin industry were studied. A kinetic study using a hot fog chamber showed that condensation is controlled by both the diffusion and permanency of the surfactant more than by the change of the surface energy developed by the wetting agents. The greatest permanency of the anti-fog effect of the LDPE/EVA surface was close to 3000 h. The contact angle results demonstrated the ability of the wetting agent to spread out to the surface. Complementarily, the migration of nonionic surfactants from the inside of the polymeric matrix to the surface was analyzed by Fourier transform infrared (FTIR) microscopy. Additionally, electrical measurement on the anti-fogging membrane at alternating currents and at a sweep frequency was proposed to test the conductivity and wetting ability of nonionic surfactants. We proved that the amphiphilic molecules had the ability to increase the conductivity in the polyolefin membrane. A correlation between the bulk electrical conductivity and the permanency of the fogging control on the LDPE/EVA coextruded film was found.

Fogging Control on LDPE/EVA Coextruded Films: Wettability Behavior and Its Correlation with Electric Performance

PubMed Central

Waldo-Mendoza, Miguel A.; Quiñones-Jurado, Zoe V.; Pérez-Medina, Juan C.; Yañez-Soto, Bernardo; Ramírez-González, Pedro E.

2017-01-01

The transformation of fog at a non-visible water layer on a membrane of low-density polyethylene (LDPE) and ethylene-vinyl acetate (EVA) was evaluated. Nonionic surfactants of major demand in the polyolefin industry were studied. A kinetic study using a hot fog chamber showed that condensation is controlled by both the diffusion and permanency of the surfactant more than by the change of the surface energy developed by the wetting agents. The greatest permanency of the anti-fog effect of the LDPE/EVA surface was close to 3000 h. The contact angle results demonstrated the ability of the wetting agent to spread out to the surface. Complementarily, the migration of nonionic surfactants from the inside of the polymeric matrix to the surface was analyzed by Fourier transform infrared (FTIR) microscopy. Additionally, electrical measurement on the anti-fogging membrane at alternating currents and at a sweep frequency was proposed to test the conductivity and wetting ability of nonionic surfactants. We proved that the amphiphilic molecules had the ability to increase the conductivity in the polyolefin membrane. A correlation between the bulk electrical conductivity and the permanency of the fogging control on the LDPE/EVA coextruded film was found. PMID:28241433

Underwater EVA training in the WETF with astronaut Robert L. Stewart

NASA Technical Reports Server (NTRS)

1983-01-01

Underwater extravehicular activity (EVA) training in the weightless environment training facility (WETF) with astronaut Robert L. Stewart. Stewart is simulating a planned EVA using the mobile foot restraint device and a one-G version of the Canadian-built remote manipulator system.

A human factors evaluation of Extravehicular Activity gloves

NASA Technical Reports Server (NTRS)

O'Hara, John M.; Briganti, Michael; Cleland, John; Winfield, Dan

1989-01-01

One of the major problems faced in Extravehicular Activity (EVA) glove development has been the absence of concise and reliable methods to measure the effects of EVA gloves on human-hand capabilities. NASA has sponsored a program to develop a standardized set of tests designed to assess EVA-gloved hand capabilities in six performance domains: Range of Motion, Strength, Tactile Perception, Dexterity, Fatigue, and Comfort. Based upon an assessment of general human-hand functioning and EVA task requirements, several tests within each performance domain were developed to provide a comprehensive evaluation. All tests were designed to be conducted in a glove box with the bare hand, an EVA glove without pressure, an EVA glove at operation pressure. Thus, the differential effect on performance of the glove with and without pressure was tested. Bare hand performance was used to 'calibrate' the effects. Ten subjects participated in the test setup as a repeated-measures experimental design. The paper will report the results of the test program.

EVA dosimetry in manned spacecraft.

PubMed

Thomson, I

1999-12-06

Extra Vehicular Activity (EVA) will become a large part of the astronaut's work on board the International Space Station (ISS). It is already well known that long duration space missions inside a spacecraft lead to radiation doses which are high enough to be a significant health risk to the crew. The doses received during EVA, however, have not been quantified to the same degree. This paper reviews the space radiation environment and the current dose limits to critical organs. Results of preliminary radiation dosimetry experiments on the external surface of the BION series of satellites indicate that EVA doses will vary considerably due to a number of factors such as EVA suit shielding, temporal fluctuations and spacecraft orbit and shielding. It is concluded that measurement of doses to crew members who engage in EVA should be done on board the spacecraft. An experiment is described which will lead the way to implementing this plan on the ISS. It is expected that results of this experiment will help future crew mitigate the risks of ionising radiation in space.

Influence of limonene on the bioavailability of nicardipine hydrochloride from membrane-moderated transdermal therapeutic systems in human volunteers.

PubMed

Krishnaiah, Y S R; Satyanarayana, V; Bhaskar, P

2002-10-24

The aim of the present study was to develop a membrane-moderated transdermal therapeutic system (TTS) of nicardipine hydrochloride using 2%w/w hydroxy propyl cellulose (HPC) gel as a reservoir system containing 4%w/w of limonene as a penetration enhancer. The permeability flux of nicardipine hydrochloride through ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate (VA) content in the copolymer. The effect of various pressure-sensitive adhesives (MA-31, MA-38 or TACKWHITE A 4MED) on the permeability of nicardipine hydrochloride through EVA membrane 2825 (28% w/w VA) or membrane/skin composite was also studied. The results showed that nicardipine hydrochloride permeability through EVA 2825 membrane coated with TACKWHITE 4A MED/skin composite was higher than that coated with MA-31or MA-38. Thus a new TTS for nicardipine hydrochloride was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE 4A MED and 2%w/w HPC gel as reservoir containing 4%w/w of limonene as a penetration enhancer. The bioavailability studies in healthy human volunteers indicated that the TTS of nicardipine hydrochloride, designed in the present study, provided steady state plasma concentration of the drug with minimal fluctuations for 20 h with improved bioavailability in comparison with the immediate release capsule dosage form. Copyright 2002 Elsevier Science B.V.

Astronaut David Scott practicing for Gemini 8 EVA

NASA Image and Video Library

1966-02-01

S66-19284 (1 Feb. 1966) --- Astronaut David R. Scott practicing for Gemini-8 extravehicular activity (EVA) in building 4 of the Manned Spacecraft Center on the air bearing floor. He is wearing the Hand-Held Maneuvering Unit which he will use during the EVA. Photo credit: NASA

Mission control activity during STS-61 EVA

NASA Image and Video Library

1993-12-07

Flight controller Susan P. Rainwater observes as two astronauts work through a lengthy period of extravehicular activity (EVA) in the cargo bay of the Earth-looking Space Shuttle Endeavour. Rainwater's EVA console was one of Mission Control's busiest during this eleven-day Hubble Space Telescope (HST) servicing mission in Earth orbit.

"Astronaut STS-123 EVA 1, NBL Training"

NASA Image and Video Library

2007-04-18

• Event (Mission for flight / Class for training): STS-118 (13A.1) • Title: STS-118 EVA 1 NBL • Date: 4-18-07 • Location: NBL • Key words: 118, 13A.1, S5, NBL • Description: NBL underwater photos of STS-118 EVA 1 S5 install.

76 FR 30143 - Proposed Agency Information Collection

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-24

... soon as possible. ADDRESSES: Written comments may be sent to: Eva Auman, GC-63; Department of Energy;1000 Independence Ave, SW.; Washington, DC 20585; Fax: 202-586-7373; E-mail: eva[email protected] . FOR... instrument and instructions should be directed to Eva Auman, GC-63; Department of Energy; 1000 Independence...

STS-49 MS Akers in OV-105's payload bay during ASEM procedures

NASA Image and Video Library

1992-05-14

STS049-77-023 (14 May 1992) --- Astronaut Thomas D. Akers joins three struts together, as fourth period of extravehicular activity (EVA) proceeds in the Space Shuttle Endeavour's cargo bay. The purpose of the final EVA on this nine-day mission was the evaluation of Assembly of Station by EVA Methods (ASEM). The scene was recorded on 70mm film by a fellow crew member in the Space Shuttle's cabin. Astronaut Kathryn C. Thornton (out of frame) joined Akers on the 7 1/2 hour EVA.

Astronaut Ronald Evans photographed during transearth coast EVA

NASA Technical Reports Server (NTRS)

1972-01-01

Astronaut Ronald E. Evans is photographed performing extravehicular activity (EVA) during the Apollo 17 spacecraft's transearth coast. During his EVA Command Module pilot Evans retrieved film cassettes from the Lunar Sounder, Mapping Camera, and Panoramic Camera. The cylindrical object at Evans left side is the mapping camera cassette. The total time for the transearth EVA was one hour seven minutes 19 seconds, starting at ground elapsed time of 257:25 (2:28 p.m.) amd ending at ground elapsed time of 258:42 (3:35 p.m.) on Sunday, December 17, 1972.

Dynamics, control and sensor issues pertinent to robotic hands for the EVA retriever system

NASA Technical Reports Server (NTRS)

Mclauchlan, Robert A.

1987-01-01

Basic dynamics, sensor, control, and related artificial intelligence issues pertinent to smart robotic hands for the Extra Vehicular Activity (EVA) Retriever system are summarized and discussed. These smart hands are to be used as end effectors on arms attached to manned maneuvering units (MMU). The Retriever robotic systems comprised of MMU, arm and smart hands, are being developed to aid crewmen in the performance of routine EVA tasks including tool and object retrieval. The ultimate goal is to enhance the effectiveness of EVA crewmen.

Man in space.

PubMed

Solovjev, V A

1987-09-01

Today, more than 20 years after the first in the world man's space walk, soviet cosmonautics gained large experience of extravehicular activity (EVA). Space suits of high reliability, onboard facilities for passing through the airlock, sets of special tools and technological rigging, as well as procedures for carrying out various EVA's were developed. In the course of the Salyut-7 space station orbital operation the EVA's have become regular. The author of the report as the participant of the EVA's considers the main steps of man activities in space and analyzes specific problems arised in performing such activities.

Astronaut Jack Lousma seen outside Skylab space station during EVA

NASA Image and Video Library

1973-08-06

S73-31976 (5 Aug. 1973) --- Astronaut Jack R. Lousma, Skylab 3 pilot, is seen outside the Skylab space station in Earth orbit during the Aug. 5, 1973 Skylab 3 extravehicular activity (EVA) in this photographic reproduction taken from a television transmission made by a color TV camera aboard the space station. Scientist-astronaut Owen K. Garriott, Skylab 3 science pilot, participated in the EVA with Lousma. During the EVA the two crewmen deployed the twin pole solar shield to help shade the Orbital Workshop. Photo credit: NASA

ESEM analysis of polymeric film in EVA-modified cement paste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, D.A.; Monteiro, P.J.M.

2005-10-01

Portland cement pastes modified by 20% weight (polymer/cement ratio) of poly(ethylene-co-vinyl acetate) (EVA) were prepared, cured, and immersed in water for 11 days. The effects of water saturation and drying on the EVA polymeric film formed in cement pastes were observed using environmental scanning electron microscopy (ESEM). This technique allowed the imaging of the EVA film even in saturated samples. The decrease of the relative humidity inside the ESEM chamber did not cause any visual modification of the polymeric film during its drying.

EVA Suit Microbial Leakage Investigation Project

NASA Technical Reports Server (NTRS)

Falker, Jay; Baker, Christopher; Clayton, Ronald; Rucker, Michelle

2016-01-01

The objective of this project is to collect microbial samples from various EVA suits to determine how much microbial contamination is typically released during simulated planetary exploration activities. Data will be released to the planetary protection and science communities, and advanced EVA system designers. In the best case scenario, we will discover that very little microbial contamination leaks from our current or prototype suit designs, in the worst case scenario, we will identify leak paths, learn more about what affects leakage--and we'll have a new, flight-certified swab tool for our EVA toolbox.

EVA-1 functions as an UNC-40 Co-receptor to enhance attraction to the MADD-4 guidance cue in Caenorhabditis elegans.

PubMed

Chan, Kevin Ka Ming; Seetharaman, Ashwin; Bagg, Rachel; Selman, Guillermo; Zhang, Yuqian; Kim, Joowan; Roy, Peter J

2014-08-01

We recently discovered a secreted and diffusible midline cue called MADD-4 (an ADAMTSL) that guides migrations along the dorsoventral axis of the nematode Caenorhabditis elegans. We showed that the transmembrane receptor, UNC-40 (DCC), whose canonical ligand is the UNC-6 (netrin) guidance cue, is required for extension towards MADD-4. Here, we demonstrate that MADD-4 interacts with an EVA-1/UNC-40 co-receptor complex to attract cell extensions. EVA-1 is a conserved transmembrane protein with predicted galactose-binding lectin domains. EVA-1 functions in the same pathway as MADD-4, physically interacts with both MADD-4 and UNC-40, and enhances UNC-40's sensitivity to the MADD-4 cue. This enhancement is especially important in the presence of UNC-6. In EVA-1's absence, UNC-6 interferes with UNC-40's responsiveness to MADD-4; in UNC-6's absence, UNC-40's responsiveness to MADD-4 is less dependent on EVA-1. By enabling UNC-40 to respond to MADD-4 in the presence of UNC-6, EVA-1 may increase the precision by which UNC-40-directed processes can reach their MADD-4-expressing targets within a field of the UNC-6 guidance cue.

EVA-1 Functions as an UNC-40 Co-receptor to Enhance Attraction to the MADD-4 Guidance Cue in Caenorhabditis elegans

PubMed Central

Bagg, Rachel; Selman, Guillermo; Zhang, Yuqian; Kim, Joowan; Roy, Peter J.

2014-01-01

We recently discovered a secreted and diffusible midline cue called MADD-4 (an ADAMTSL) that guides migrations along the dorsoventral axis of the nematode Caenorhabditis elegans. We showed that the transmembrane receptor, UNC-40 (DCC), whose canonical ligand is the UNC-6 (netrin) guidance cue, is required for extension towards MADD-4. Here, we demonstrate that MADD-4 interacts with an EVA-1/UNC-40 co-receptor complex to attract cell extensions. EVA-1 is a conserved transmembrane protein with predicted galactose-binding lectin domains. EVA-1 functions in the same pathway as MADD-4, physically interacts with both MADD-4 and UNC-40, and enhances UNC-40's sensitivity to the MADD-4 cue. This enhancement is especially important in the presence of UNC-6. In EVA-1's absence, UNC-6 interferes with UNC-40's responsiveness to MADD-4; in UNC-6's absence, UNC-40's responsiveness to MADD-4 is less dependent on EVA-1. By enabling UNC-40 to respond to MADD-4 in the presence of UNC-6, EVA-1 may increase the precision by which UNC-40-directed processes can reach their MADD-4-expressing targets within a field of the UNC-6 guidance cue. PMID:25122090

Hand, Foot, and Mouth Disease in China: Modeling Epidemic Dynamics of Enterovirus Serotypes and Implications for Vaccination

PubMed Central

Takahashi, Saki; Liao, Qiaohong; Van Boeckel, Thomas P.; Xing, Weijia; Sun, Junling; Hsiao, Victor Y.; Metcalf, C. Jessica E.; Chang, Zhaorui; Liu, Fengfeng; Zhang, Jing; Wu, Joseph T.; Cowling, Benjamin J.; Leung, Gabriel M.; Farrar, Jeremy J.; van Doorn, H. Rogier; Grenfell, Bryan T.; Yu, Hongjie

2016-01-01

Background Hand, foot, and mouth disease (HFMD) is a common childhood illness caused by serotypes of the Enterovirus A species in the genus Enterovirus of the Picornaviridae family. The disease has had a substantial burden throughout East and Southeast Asia over the past 15 y. China reported 9 million cases of HFMD between 2008 and 2013, with the two serotypes Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CV-A16) being responsible for the majority of these cases. Three recent phase 3 clinical trials showed that inactivated monovalent EV-A71 vaccines manufactured in China were highly efficacious against HFMD associated with EV-A71, but offered no protection against HFMD caused by CV-A16. To better inform vaccination policy, we used mathematical models to evaluate the effect of prospective vaccination against EV-A71-associated HFMD and the potential risk of serotype replacement by CV-A16. We also extended the model to address the co-circulation, and implications for vaccination, of additional non-EV-A71, non-CV-A16 serotypes of enterovirus. Methods and Findings Weekly reports of HFMD incidence from 31 provinces in Mainland China from 1 January 2009 to 31 December 2013 were used to fit multi-serotype time series susceptible–infected–recovered (TSIR) epidemic models. We obtained good model fit for the two-serotype TSIR with cross-protection, capturing the seasonality and geographic heterogeneity of province-level transmission, with strong correlation between the observed and simulated epidemic series. The national estimate of the basic reproduction number, R 0, weighted by provincial population size, was 26.63 for EV-A71 (interquartile range [IQR]: 23.14, 30.40) and 27.13 for CV-A16 (IQR: 23.15, 31.34), with considerable variation between provinces (however, predictions about the overall impact of vaccination were robust to this variation). EV-A71 incidence was projected to decrease monotonically with higher coverage rates of EV-A71 vaccination. Across provinces, CV-A16 incidence in the post-EV-A71-vaccination period remained either comparable to or only slightly increased from levels prior to vaccination. The duration and strength of cross-protection following infection with EV-A71 or CV-A16 was estimated to be 9.95 wk (95% confidence interval [CI]: 3.31, 23.40) in 68% of the population (95% CI: 37%, 96%). Our predictions are limited by the necessarily short and under-sampled time series and the possible circulation of unidentified serotypes, but, nonetheless, sensitivity analyses indicate that our results are robust in predicting that the vaccine should drastically reduce incidence of EV-A71 without a substantial competitive release of CV-A16. Conclusions The ability of our models to capture the observed epidemic cycles suggests that herd immunity is driving the epidemic dynamics caused by the multiple serotypes of enterovirus. Our results predict that the EV-A71 and CV-A16 serotypes provide a temporary immunizing effect against each other. Achieving high coverage rates of EV-A71 vaccination would be necessary to eliminate the ongoing transmission of EV-A71, but serotype replacement by CV-A16 following EV-A71 vaccination is likely to be transient and minor compared to the corresponding reduction in the burden of EV-A71-associated HFMD. Therefore, a mass EV-A71 vaccination program of infants and young children should provide significant benefits in terms of a reduction in overall HFMD burden. PMID:26882540

Hand, Foot, and Mouth Disease in China: Modeling Epidemic Dynamics of Enterovirus Serotypes and Implications for Vaccination.

PubMed

Takahashi, Saki; Liao, Qiaohong; Van Boeckel, Thomas P; Xing, Weijia; Sun, Junling; Hsiao, Victor Y; Metcalf, C Jessica E; Chang, Zhaorui; Liu, Fengfeng; Zhang, Jing; Wu, Joseph T; Cowling, Benjamin J; Leung, Gabriel M; Farrar, Jeremy J; van Doorn, H Rogier; Grenfell, Bryan T; Yu, Hongjie

2016-02-01

Hand, foot, and mouth disease (HFMD) is a common childhood illness caused by serotypes of the Enterovirus A species in the genus Enterovirus of the Picornaviridae family. The disease has had a substantial burden throughout East and Southeast Asia over the past 15 y. China reported 9 million cases of HFMD between 2008 and 2013, with the two serotypes Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CV-A16) being responsible for the majority of these cases. Three recent phase 3 clinical trials showed that inactivated monovalent EV-A71 vaccines manufactured in China were highly efficacious against HFMD associated with EV-A71, but offered no protection against HFMD caused by CV-A16. To better inform vaccination policy, we used mathematical models to evaluate the effect of prospective vaccination against EV-A71-associated HFMD and the potential risk of serotype replacement by CV-A16. We also extended the model to address the co-circulation, and implications for vaccination, of additional non-EV-A71, non-CV-A16 serotypes of enterovirus. Weekly reports of HFMD incidence from 31 provinces in Mainland China from 1 January 2009 to 31 December 2013 were used to fit multi-serotype time series susceptible-infected-recovered (TSIR) epidemic models. We obtained good model fit for the two-serotype TSIR with cross-protection, capturing the seasonality and geographic heterogeneity of province-level transmission, with strong correlation between the observed and simulated epidemic series. The national estimate of the basic reproduction number, R0, weighted by provincial population size, was 26.63 for EV-A71 (interquartile range [IQR]: 23.14, 30.40) and 27.13 for CV-A16 (IQR: 23.15, 31.34), with considerable variation between provinces (however, predictions about the overall impact of vaccination were robust to this variation). EV-A71 incidence was projected to decrease monotonically with higher coverage rates of EV-A71 vaccination. Across provinces, CV-A16 incidence in the post-EV-A71-vaccination period remained either comparable to or only slightly increased from levels prior to vaccination. The duration and strength of cross-protection following infection with EV-A71 or CV-A16 was estimated to be 9.95 wk (95% confidence interval [CI]: 3.31, 23.40) in 68% of the population (95% CI: 37%, 96%). Our predictions are limited by the necessarily short and under-sampled time series and the possible circulation of unidentified serotypes, but, nonetheless, sensitivity analyses indicate that our results are robust in predicting that the vaccine should drastically reduce incidence of EV-A71 without a substantial competitive release of CV-A16. The ability of our models to capture the observed epidemic cycles suggests that herd immunity is driving the epidemic dynamics caused by the multiple serotypes of enterovirus. Our results predict that the EV-A71 and CV-A16 serotypes provide a temporary immunizing effect against each other. Achieving high coverage rates of EV-A71 vaccination would be necessary to eliminate the ongoing transmission of EV-A71, but serotype replacement by CV-A16 following EV-A71 vaccination is likely to be transient and minor compared to the corresponding reduction in the burden of EV-A71-associated HFMD. Therefore, a mass EV-A71 vaccination program of infants and young children should provide significant benefits in terms of a reduction in overall HFMD burden.

Genetic evolution of Human Enterovirus A71 subgenotype C4 in Shenzhen, China, 1998-2013.

PubMed

He, Yaqing; Zou, Linjie; Chong, Marc Ka Chun; Men, Ruoting; Xu, Wenbo; Yang, Hong; Yao, Xiangjie; Chen, Long; Xian, Huixia; Zhang, Hailong; Luo, Min; Cheng, Jinquan; Ma, Hanwu; Feng, Qianjin; Huang, Yun; Wang, Yujie; Yeoh, Eng-Kiong; Zee, Benny Chung-Ying; Zhou, Yuanping; He, Ming-Liang; Wang, Maggie Haitian

2016-06-01

Human Enterovirus A71 (EV-A71) is one of the severest enteroviruses that causes hand, foot, and mouth disease (HFMD) among children. This study identified the mutations of EV-A71 VP1 amino acid residues over a number of years and explored the possible association of identified mutations and HFMD epidemic outbreaks in Shenzhen, China. A total of 3760 stool specimens were collected from HFMD patients by Shenzhen Centers for Disease Control and Prevention (CDC) between 1998 and 2013. In total 289 VP1 strains were sequenced in this study, and amino acids mutation frequency was calculated. There were 2040 China nationwide sequences downloaded from Genebank as replication data. In our samples, 1036 subjects (27.6%) were EV-A71 infected. Three amino acid positions on VP1 protein were found to have high mutation prevalence. These are Q22H, S283T, and A289H. Site 22 showed a fast mutation fixation in the year 2008, at the time of the large scale epidemic outbreak in Shenzhen. Analysis of the nationwide data replicated the same trend of mutation prevalence of the three sites. The switching from Q to H on site 22 of the EV-A71 VP1 strain might be associated with the HFMD outbreak in Shenzhen in 2008. The identified amino acid sites 22, 283 and 289 provided information for developing anti-viral drugs against EV-A71 in the future. Copyright © 2016 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Desert Research and Technology Study 2003 Trip Report/ICES Paper

NASA Technical Reports Server (NTRS)

Ross, Amy; Kosmo, Joseph J.; Janoiko, Barbara; Eppler, Dean

2004-01-01

The Advanced Extra-vehicular Activity (EVA) team of the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) Crew and Thermal Systems Division (CTSD) participated in the Desert Research and Technology Study (RATS) in September 2003, at Meteor Crater, AZ. The Desert RATS is an integrated remote field site te t with team members from several NASA centers (Johnson Space Center; Glenn and Ames Research Centers) and universities (Bowling Green State University, University of Cincinnati, Massachusetts Institute of Technology) participating. Each week of the two-week field test had a primary focus. The primary test hardware for the first week was the I-Gravity Lunar Rover Training Vehicle, or Grover, which was on loan to NASA from the United States Geological Survey (USGS) Astrogeology Research Program. The 2003 Grover driving test results serve as a rover performance characterization baseline for the Science, Crew, Operation and Utility Testbed (SCOUT) project team, which will be designing and fabricating a next generation roving vehicle prototype in Fiscal Year (FY) 2004. The second week of testing focused on EVA geologic traverses that utilized a geologic sample field analysis science trailer and also focused on human-robotic interaction between the suited subjects and the EVA Robotic Assistant (ERA). This paper will review the Advanced EVA team's role in the context of the overall Desert RATS, as well as the EVA team results and lessons learned. For information regarding other test participants' results, the authors can refer interested parties to the test reports produced by those Desert RATS teams.

Characterization of three small molecule inhibitors of enterovirus 71 identified from screening of a library of natural products.

PubMed

Li, Guiming; Gao, Qianqian; Yuan, Shilin; Wang, Lili; Altmeyer, Ralf; Lan, Ke; Yin, Feifei; Zou, Gang

2017-07-01

Enterovirus 71 (EV-A71) is a major cause of hand, foot, and mouth disease (HFMD). Infection with EV-A71 is more often associated with neurological complications in children and is responsible for the majority of fatalities, but currently there is no approved antiviral therapy for treatment. Here, we identified auraptene, formononetin, and yangonin as effective inhibitors of EV-A71 infection in the low-micromolar range from screening of a natural product library. Among them, formononetin and yangonin selectively inhibited EV-A71 while auraptene could inhibit viruses within the enterovirus species A. Time of addition studies showed that all the three inhibitors inhibit both attachment and postattachment step of entry. We found mutations conferring the resistance to these inhibitors in the VP1 and VP4 capsid proteins and confirmed the target residues using a reverse genetic approach. Interestingly, auraptene- and formononetin-resistant viruses exhibit cross-resistance to other inhibitors while yangonin-resistant virus still remains susceptible to auraptene and formononetin. Moreover, auraptene and formononetin, but not yangonin protected EV-A71 against thermal inactivation, indicating a direct stabilizing effect of both compounds on virion capsid conformation. Finally, neither biochanin A (an analog of formononetin) nor DL-Kavain (an analog of yangonin) exhibited anti-EV-A71 activity, suggesting the structural elements required for anti-EV-A71 activity. Taken together, these compounds could become potential lead compounds for anti-EV-A71 drug development and also serve as tool compounds for studying virus entry. Copyright © 2017 Elsevier B.V. All rights reserved.

Ethylene vinyl acetate (EVA) as a new drug carrier for 3D printed medical drug delivery devices.

PubMed

Genina, Natalja; Holländer, Jenny; Jukarainen, Harri; Mäkilä, Ermei; Salonen, Jarno; Sandler, Niklas

2016-07-30

The main purpose of this work was to investigate the printability of different grades of ethylene vinyl acetate (EVA) copolymers as new feedstock material for fused-deposition modeling (FDM™)-based 3D printing technology in fabrication of custom-made T-shaped intrauterine systems (IUS) and subcutaneous rods (SR). The goal was to select an EVA grade with optimal properties, namely vinyl acetate content, melting index, flexural modulus, for 3D printing of implantable prototypes with the drug incorporated within the entire matrix of the medical devices. Indomethacin was used as a model drug in this study. Out of the twelve tested grades of the EVA five were printable. One of them showed superior print quality and was further investigated by printing drug-loaded filaments, containing 5% and 15% indomethacin. The feedstock filaments were fabricated by hot-melt extrusion (HME) below the melting point of the drug substance and the IUS and SR were successfully printed at the temperature above the melting point of the drug. As a result, the drug substance in the printed prototypes showed to be at least partly amorphous, while the drug in the corresponding HME filaments was crystalline. This difference affected the drug release profiles from the filaments and printed prototype products: faster release from the prototypes over 30days in the in vitro tests. To conclude, this study indicates that certain grades of EVA were applicable feedstock material for 3D printing to produce drug-loaded implantable prototypes. Copyright © 2015 Elsevier B.V. All rights reserved.

Assessment of Health-Cost Externalities of Air Pollution at the National Level using the EVA Model System

NASA Astrophysics Data System (ADS)

Brandt, Jørgen; Silver, Jeremy David; Heile Christensen, Jesper; Skou Andersen, Mikael; Geels, Camilla; Gross, Allan; Buus Hansen, Ayoe; Mantzius Hansen, Kaj; Brandt Hedegaard, Gitte; Ambelas Skjøth, Carsten

2010-05-01

Air pollution has significant negative impacts on human health and well-being, which entail substantial economic consequences. We have developed an integrated model system, EVA (External Valuation of Air pollution), to assess health-related economic externalities of air pollution resulting from specific emission sources/sectors. The EVA system was initially developed to assess externalities from power production, but in this study it is extended to evaluate costs at the national level. The EVA system integrates a regional-scale atmospheric chemistry transport model (DEHM), address-level population data, exposure-response functions and monetary values applicable for Danish/European conditions. Traditionally, systems that assess economic costs of health impacts from air pollution assume linear approximations in the source-receptor relationships. However, atmospheric chemistry is non-linear and therefore the uncertainty involved in the linear assumption can be large. The EVA system has been developed to take into account the non-linear processes by using a comprehensive, state-of-the-art chemical transport model when calculating how specific changes to emissions affect air pollution levels and the subsequent impacts on human health and cost. Furthermore, we present a new "tagging" method, developed to examine how specific emission sources influence air pollution levels without assuming linearity of the non-linear behaviour of atmospheric chemistry. This method is more precise than the traditional approach based on taking the difference between two concentration fields. Using the EVA system, we have estimated the total external costs from the main emission sectors in Denmark, representing the ten major SNAP codes. Finally, we assess the impacts and external costs of emissions from international ship traffic around Denmark, since there is a high volume of ship traffic in the region.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holley, W.A.

The goals of the NREL PVMaT program are, among others, to reduce module manufacturing costs and improve the quality, and we might add here the reliability, of manufactured PV products. One component critical to the service life of PV modules is the useful life of the EVA resin-based encapsulant which is employed extensively by module manufacturers on a worldwide basis. This pottant has been in commercial use since 1982, and over that time has proven to be a dependable material from the standpoint of production, module fabrication, and end-use. But despite the widespread acceptance of the EVA resin-based A9918 andmore » similar formulations for PV encapsulation, some module producers, end-users, and investigators have reported a yellowing or browning phenomenon with EVA resin-based encapsulants in the field. Wile the incidence of this discoloration/degradation appeared at comparatively few sites at the time that this present program was conceived, it raised serious concern as to the long term reliability of EVA resin-based encapsulation systems. Consequently, under the NREL PVMaT program, Springborn Laboratories proposed a comprehensive study of the EVA aging and discoloration problem and its possible solution(s). During the first year of this program, accelerated U.V. aging methods were surveyed. On careful review of the various types of accelerated U.V. aging equipment available, an Atlas Ci35A Weather-Ometer Xenon Exposure System was selected as appropriate equipment for this work. The following report summarizes how this accelerated aging technique has been used to develop a family of solutions to the discoloration problem, the most significant of which is a series of EVA-based encapsulants which are resistant to discoloration.« less

The MADD-3 LAMMER Kinase Interacts with a p38 MAP Kinase Pathway to Regulate the Display of the EVA-1 Guidance Receptor in Caenorhabditis elegans.

PubMed

D'Souza, Serena A; Rajendran, Luckshika; Bagg, Rachel; Barbier, Louis; van Pel, Derek M; Moshiri, Houtan; Roy, Peter J

2016-04-01

The proper display of transmembrane receptors on the leading edge of migrating cells and cell extensions is essential for their response to guidance cues. We previously discovered that MADD-4, which is an ADAMTSL secreted by motor neurons in Caenorhabditis elegans, interacts with an UNC-40/EVA-1 co-receptor complex on muscles to attract plasma membrane extensions called muscle arms. In nematodes, the muscle arm termini harbor the post-synaptic elements of the neuromuscular junction. Through a forward genetic screen for mutants with disrupted muscle arm extension, we discovered that a LAMMER kinase, which we call MADD-3, is required for the proper display of the EVA-1 receptor on the muscle's plasma membrane. Without MADD-3, EVA-1 levels decrease concomitantly with a reduction of the late-endosomal marker RAB-7. Through a genetic suppressor screen, we found that the levels of EVA-1 and RAB-7 can be restored in madd-3 mutants by eliminating the function of a p38 MAP kinase pathway. We also found that EVA-1 and RAB-7 will accumulate in madd-3 mutants upon disrupting CUP-5, which is a mucolipin ortholog required for proper lysosome function. Together, our data suggests that the MADD-3 LAMMER kinase antagonizes the p38-mediated endosomal trafficking of EVA-1 to the lysosome. In this way, MADD-3 ensures that sufficient levels of EVA-1 are present to guide muscle arm extension towards the source of the MADD-4 guidance cue.

The MADD-3 LAMMER Kinase Interacts with a p38 MAP Kinase Pathway to Regulate the Display of the EVA-1 Guidance Receptor in Caenorhabditis elegans

PubMed Central

D’Souza, Serena A.; Rajendran, Luckshika; Bagg, Rachel; van Pel, Derek M.; Moshiri, Houtan; Roy, Peter J.

2016-01-01

The proper display of transmembrane receptors on the leading edge of migrating cells and cell extensions is essential for their response to guidance cues. We previously discovered that MADD-4, which is an ADAMTSL secreted by motor neurons in Caenorhabditis elegans, interacts with an UNC-40/EVA-1 co-receptor complex on muscles to attract plasma membrane extensions called muscle arms. In nematodes, the muscle arm termini harbor the post-synaptic elements of the neuromuscular junction. Through a forward genetic screen for mutants with disrupted muscle arm extension, we discovered that a LAMMER kinase, which we call MADD-3, is required for the proper display of the EVA-1 receptor on the muscle’s plasma membrane. Without MADD-3, EVA-1 levels decrease concomitantly with a reduction of the late-endosomal marker RAB-7. Through a genetic suppressor screen, we found that the levels of EVA-1 and RAB-7 can be restored in madd-3 mutants by eliminating the function of a p38 MAP kinase pathway. We also found that EVA-1 and RAB-7 will accumulate in madd-3 mutants upon disrupting CUP-5, which is a mucolipin ortholog required for proper lysosome function. Together, our data suggests that the MADD-3 LAMMER kinase antagonizes the p38-mediated endosomal trafficking of EVA-1 to the lysosome. In this way, MADD-3 ensures that sufficient levels of EVA-1 are present to guide muscle arm extension towards the source of the MADD-4 guidance cue. PMID:27123983

The transformed-stationary approach: a generic and simplified methodology for non-stationary extreme value analysis

NASA Astrophysics Data System (ADS)

Mentaschi, Lorenzo; Vousdoukas, Michalis; Voukouvalas, Evangelos; Sartini, Ludovica; Feyen, Luc; Besio, Giovanni; Alfieri, Lorenzo

2016-09-01

Statistical approaches to study extreme events require, by definition, long time series of data. In many scientific disciplines, these series are often subject to variations at different temporal scales that affect the frequency and intensity of their extremes. Therefore, the assumption of stationarity is violated and alternative methods to conventional stationary extreme value analysis (EVA) must be adopted. Using the example of environmental variables subject to climate change, in this study we introduce the transformed-stationary (TS) methodology for non-stationary EVA. This approach consists of (i) transforming a non-stationary time series into a stationary one, to which the stationary EVA theory can be applied, and (ii) reverse transforming the result into a non-stationary extreme value distribution. As a transformation, we propose and discuss a simple time-varying normalization of the signal and show that it enables a comprehensive formulation of non-stationary generalized extreme value (GEV) and generalized Pareto distribution (GPD) models with a constant shape parameter. A validation of the methodology is carried out on time series of significant wave height, residual water level, and river discharge, which show varying degrees of long-term and seasonal variability. The results from the proposed approach are comparable with the results from (a) a stationary EVA on quasi-stationary slices of non-stationary series and (b) the established method for non-stationary EVA. However, the proposed technique comes with advantages in both cases. For example, in contrast to (a), the proposed technique uses the whole time horizon of the series for the estimation of the extremes, allowing for a more accurate estimation of large return levels. Furthermore, with respect to (b), it decouples the detection of non-stationary patterns from the fitting of the extreme value distribution. As a result, the steps of the analysis are simplified and intermediate diagnostics are possible. In particular, the transformation can be carried out by means of simple statistical techniques such as low-pass filters based on the running mean and the standard deviation, and the fitting procedure is a stationary one with a few degrees of freedom and is easy to implement and control. An open-source MATLAB toolbox has been developed to cover this methodology, which is available at https://github.com/menta78/tsEva/ (Mentaschi et al., 2016).

An Alternative Approach to Human Servicing of Crewed Earth Orbiting Spacecraft

NASA Technical Reports Server (NTRS)

Mularski, John R.; Alpert, Brian K.

2017-01-01

As crewed spacecraft have grown larger and more complex, they have come to rely on spacewalks, or Extravehicular Activities (EVA), for assembly and to assure mission success. Typically, these spacecraft maintain all of the hardware and trained personnel needed to perform an EVA on-board at all times. Maintaining this capability requires up-mass, volume for storage of EVA hardware, crew time for ground and on-orbit training, and on-orbit maintenance of EVA hardware. This paper proposes an alternative methodology, utilizing either launch-on-need hardware and crew or regularly scheduled missions to provide EVA capability for space stations in low Earth orbit after assembly complete. Much the same way that one would call a repairman to fix something at their home these EVAs are dedicated to maintenance and upgrades of the orbiting station. For crew safety contingencies it is assumed the station would be designed such the crew could either solve those issues from inside the spacecraft or use the docked Earth to Orbit vehicles as a return lifeboat, in the same manner as the International Space Station (ISS) which does not rely on EVA for crew safety related contingencies. This approach would reduce ground training requirements for long duration crews, save Intravehicular Activity (IVA) crew time in the form of EVA hardware maintenance and on-orbit training, and lead to more efficient EVAs because they would be performed by specialists with detailed knowledge and training stemming from their direct involvement in the development of the EVA. The on-orbit crew would then be available to focus on the immediate response to any failures such as IVA systems reconfiguration or jumper installation as well as the day-to-day operations of the spacecraft and payloads. This paper will look at how current unplanned EVAs are conducted on ISS, including the time required for preparation, and offer an alternative for future spacecraft. As this methodology relies on the on-time and on-need launch of spacecraft, any space station that utilized this approach would need a robust transportation system, possibly including more than one launch vehicle capable of carrying crew. In addition, the fault tolerance of the future space station would be an important consideration in how much time was available for EVA preparation after the failure. Ideally the fault tolerance of the station would allow for the maintenance tasks to be grouped such that they could be handled by regularly scheduled maintenance visits and not contingency launches. Each future program would have to weigh the risk of on-time launch against the increase in available crew time for the main objective of the spacecraft. This is only one of several ideas that could be used to reduce or eliminate a station's reliance on rapid turnaround EVAs using on-board crew. Others could include having shirt-sleeve access to critical systems or utilizing low pressure temporarily pressurized equipment bays.

EVA 4 - Massimino during EVA

NASA Image and Video Library

2002-03-07

STS109-323-013 (7 March 2002) --- Astronaut Michael J. Massimino moves about in the cargo bay of the Space Shuttle Columbia while performing work on the Hubble Space Telescope (HST), partially visible behind him. Astronauts Massimino and James H. Newman (out of frame), mission specialists, were participating in the fourth STS-109 space walk (EVA-4).

Extravehicular activity training and hardware design consideration

NASA Technical Reports Server (NTRS)

Thuot, P. J.; Harbaugh, G. J.

1995-01-01

Preparing astronauts to perform the many complex extravehicular activity (EVA) tasks required to assemble and maintain Space Station will be accomplished through training simulations in a variety of facilities. The adequacy of this training is dependent on a thorough understanding of the task to be performed, the environment in which the task will be performed, high-fidelity training hardware and an awareness of the limitations of each particular training facility. Designing hardware that can be successfully operated, or assembled, by EVA astronauts in an efficient manner, requires an acute understanding of human factors and the capabilities and limitations of the space-suited astronaut. Additionally, the significant effect the microgravity environment has on the crew members' capabilities has to be carefully considered not only for each particular task, but also for all the overhead related to the task and the general overhead associated with EVA. This paper will describe various training methods and facilities that will be used to train EVA astronauts for Space Station assembly and maintenance. User-friendly EVA hardware design considerations and recent EVA flight experience will also be presented.

Biosensors for EVA: Muscle Oxygen and pH During Walking, Running and Simulated Reduced Gravity

NASA Technical Reports Server (NTRS)

Lee, S. M. C.; Ellerby, G.; Scott, P.; Stroud, L.; Norcross, J.; Pesholov, B.; Zou, F.; Gernhardt, M.; Soller, B.

2009-01-01

During lunar excursions in the EVA suit, real-time measurement of metabolic rate is required to manage consumables and guide activities to ensure safe return to the base. Metabolic rate, or oxygen consumption (VO2), is normally measured from pulmonary parameters but cannot be determined with standard techniques in the oxygen-rich environment of a spacesuit. Our group developed novel near infrared spectroscopic (NIRS) methods to calculate muscle oxygen saturation (SmO2), hematocrit, and pH, and we recently demonstrated that we can use our NIRS sensor to measure VO2 on the leg during cycling. Our NSBRI-funded project is looking to extend this methodology to examine activities which more appropriately represent EVA activities, such as walking and running and to better understand factors that determine the metabolic cost of exercise in both normal and lunar gravity. Our 4 year project specifically addresses risk: ExMC 4.18: Lack of adequate biomedical monitoring capability for Constellation EVA Suits and EPSP risk: Risk of compromised EVA performance and crew health due to inadequate EVA suit systems.

Extravehicular activity training and hardware design consideration.

PubMed

Thuot, P J; Harbaugh, G J

1995-07-01

Preparing astronauts to perform the many complex extravehicular activity (EVA) tasks required to assemble and maintain Space Station will be accomplished through training simulations in a variety of facilities. The adequacy of this training is dependent on a thorough understanding of the task to be performed, the environment in which the task will be performed, high-fidelity training hardware and an awareness of the limitations of each particular training facility. Designing hardware that can be successfully operated, or assembled, by EVA astronauts in an efficient manner, requires an acute understanding of human factors and the capabilities and limitations of the space-suited astronaut. Additionally, the significant effect the microgravity environment has on the crew members' capabilities has to be carefully considered not only for each particular task, but also for all the overhead related to the task and the general overhead associated with EVA. This paper will describe various training methods and facilities that will be used to train EVA astronauts for Space Station assembly and maintenance. User-friendly EVA hardware design considerations and recent EVA flight experience will also be presented.

Investigation of test methods, material properties, and processes for solar cell encapsulants. Fourteenth quarterly progress report, August 12, 1978-November 12, 1979. [EVA, EPDM, aliphatic urethane, PVC plastisol, and butyl acrylate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Willis, P. B.; Baum, B.; Schnitzer, H. S.

1979-12-01

Springborn Laboratories is engaged in a study of evaluating potentially useful encapsulating materials for Task 3 of the Low-Cost Silicon Solar Array project (LSA) funded by DOE. The goal of this program is to identify, evaluate, and recommend encapsulant materials and processes for the production of cost-effective, long-life solar cell modules. This report presents the results of a cost analysis of candidate potting compounds for long life solar module encapsulation. Additionally, the two major encapsulation processes, sheet lamination and liquid casting, are costed on the basis of a large scale production facility. Potting compounds studied include EVA, sheet, clear; EVA,more » sheet, pigmented; EPDM, sheet, clear; Aliphatic urethane, syrup; PVC Plastisol; Butyl acrylate, syrup; and Butyl acrylate, sheet.« less

Asteroid Redirect Crewed Mission Space Suit and EVA System Architecture Trade Study

NASA Technical Reports Server (NTRS)

Bowie, Jonathan; Buffington, Jesse; Hood, Drew; Kelly, Cody; Naids, Adam; Watson, Richard; Blanco, Raul; Sipila, Stephanie

2014-01-01

The Asteroid Redirect Crewed Mission (ARCM) requires a Launch/Entry/Abort (LEA) suit capability and short duration Extra Vehicular Activity (EVA) capability from the Orion spacecraft. For this mission, the pressure garment selected for both functions is the Modified Advanced Crew Escape Suit (MACES) with EVA enhancements and the life support option that was selected is the Exploration Portable Life Support System (PLSS) currently under development for Advanced Exploration Systems (AES). The proposed architecture meets the ARCM constraints, but much more work is required to determine the details of the suit upgrades, the integration with the PLSS, and the tools and equipment necessary to accomplish the mission. This work has continued over the last year to better define the operations and hardware maturation of these systems. EVA simulations were completed in the Neutral Buoyancy Lab (NBL) and interfacing options were prototyped and analyzed with testing planned for late 2014. This paper discusses the work done over the last year on the MACES enhancements, the use of tools while using the suit, and the integration of the PLSS with the MACES.

Electrical Currents and Adhesion of Edge-Delete Regions of EVA-to-Glass Module Packaging: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMahon, T. J.; Jorgensen, G. J.

2001-10-01

Presented at the 2001 NCPV Program Review Meeting: Electrical conductivity pathways from the grounded frame to the cell area in a PV module are reviewed here. Electrical conductivity pathways from the grounded frame to the cell area in a PV module are reviewed here. Measurements are made on 4 inch x 8 inch soda lime (SL) glass substrates with contact patterns defined using 3-mil and 10-mil diameter bead-blast removal of the SnO{sub 2} coating to study the dominant path, which is the EVA/glass interface. The remaining SnO{sub 2} contact strips are separated by what would simulate the module edge deletemore » regions. EVA encapsulated bead-blast surface resistances are 8 x 10{sup 15} ohm/sq compared to 8 x 10{sup 12} ohm/sq for native SL glass surfaces. Adhesion strengths to bead-blast surfaces are 25 to 30 lbs/in. Stress test results on these interfaces after removal from damp heat suggest corrosion of the glass at the glass-EVA interface.« less

Enhancing the thermal conductivity of ethylene-vinyl acetate (EVA) in a photovoltaic thermal collector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allan, J., E-mail: james.p.allan14@gmail.com; ChapmanBDSP, Saffron House, 6-10 Kirby Street, London, EC1N 8EQ; Pinder, H.

2016-03-15

Samples of Ethylene-Vinyl Acetate (EVA) were doped with particles of Boron Nitride (BN) in concentrations ranging from 0-60% w/w. Thermal conductivity was measured using a Differential Scanning Calorimetery (DSC) technique. The thermal conductivity of parent EVA was increased from 0.24 W/m ⋅ K to 0.80 W/m ⋅ K for the 60% w/w sample. Two PV laminates were made; one using the parent EVA the other using EVA doped with 50% BN. When exposed to a one directional heat flux the doped laminate was, on average, 6% cooler than the standard laminate. A finite difference model had good agreement with experimentalmore » results and showed that the use of 60% BN composite achieved a PV performance increase of 0.3% compared to the standard laminate.« less

The Potential of Wearable Sensor Technology for EVA Glove Ergonomic Evaluation

NASA Technical Reports Server (NTRS)

Reid, Christopher R.; McFarland, Shane M.; Norcross, Jason R.; Rajulu, Sudhakar

2014-01-01

Injuries to the hands are common among astronauts who train for extravehicular activity (EVA). Many of these injuries refer to the gloves worn during EVA as the root cause. While pressurized, the bladder and outer material of these gloves restrict movement and create pressure points while performing tasks, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally a more severe injury, onycholysis (fingernail delamination). The most common injury causes are glove contact (pressure point/rubbing), ill-fitting gloves, and/or performing EVA tasks in pressurized gloves. A brief review of the Lifetime Surveillance of Astronaut Health's injury database reveals over 57% of the total injuries to the upper extremities during EVA training occurred either to the metacarpophalangeal (MCP) joint, fingernail, or the fingertip. Twenty-five of these injuries resulted in a diagnosis of onycholysis.

The Potential of Wearable Sensor Technology for EVA Glove Ergonomic Evaluation

NASA Technical Reports Server (NTRS)

Reid, Christopher R.; McFarland, Shane; Norcross, Jason R.; Rajulu, Sudhakar

2014-01-01

Injuries to the hands are common among astronauts who train for extravehicular activity (EVA). Many of these injuries refer to the gloves worn during EVA as the root cause. While pressurized, the bladder and outer material of these gloves restrict movement and create pressure points while performing tasks, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally a more severe injury, onycholysis (fingernail delamination). The most common injury causes are glove contact (pressure point/rubbing), ill-fitting gloves, and/or performing EVA tasks in pressurized gloves. A brief review of the Lifetime Surveillance of Astronaut Health's injury database reveals over 57% of the total injuries to the upper extremities during EVA training occurred either to the metacarpophalangeal (MCP) joint, fingernail, or the fingertip. Twenty-five of these injuries resulted in a diagnosis of onycholysis

Plasma Hazards and Acceptance for International Space Station Extravehicular Activities

NASA Astrophysics Data System (ADS)

Patton, Thomas

2010-09-01

Extravehicular activity(EVA) is accepted by NASA and other space faring agencies as a necessary risk in order to build and maintain a safe and efficient laboratory in space. EVAs are used for standard construction and as contingency operations to repair critical equipment for vehicle sustainability and safety of the entire crew in the habitable volume. There are many hazards that are assessed for even the most mundane EVA for astronauts, and the vast majority of these are adequately controlled per the rules of the International Space Station Program. The need for EVA repair and construction has driven acceptance of a possible catastrophic hazard to the EVA crewmember which cannot currently be controlled adequately. That hazard is electrical shock from the very environment in which they work. This paper describes the environment, causes and contributors to the shock of EVA crewmembers attributed to the ionospheric plasma environment in low Earth orbit. It will detail the hazard history, and acceptance process for the risk associated with these hazards that give assurance to a safe EVA. In addition to the hazard acceptance process this paper will explore other factors that go into the decision to accept a risk including criticality of task, hardware design and capability, and the probability of hazard occurrence. Also included will be the required interaction between organizations at NASA(EVA Office, Environments, Engineering, Mission Operations, Safety) in order to build and eventually gain adequate acceptance rationale for a hazard of this kind. During the course of the discussion, all current methods of mitigating the hazard will be identified. This paper will capture the history of the plasma hazard analysis and processes used by the International Space Station Program to formally assess and qualify the risk. The paper will discuss steps that have been taken to identify and perform required analysis of the floating potential shock hazard from the ISS environment which eventually led to its status as an accepted risk for ISS EVAs.

Overview of EVA PRA for TPS Repair for Hubble Space Telescope Servicing Mission

NASA Technical Reports Server (NTRS)

Bigler, Mark; Duncan, Gary; Roeschel, Eduardo; Canga, Michael

2010-01-01

Following the Columbia accident in 2003, NASA developed techniques to repair the Thermal Protection System (TPS) in the event of damage to the TPS as one of several actions to reduce the risk to future flights from ascent debris, micro-meteoroid and/or orbital debris (MMOD). Other actions to help reduce the risk include improved inspection techniques, reduced shedding of debris from the External Tank and ability to rescue the crew with a launch on need vehicle. For the Hubble Space Telescope (HST) Servicing Mission the crew rescue capability was limited by the inability to safe haven on the International Space Station (ISS), resulting in a greater reliance on the repair capability. Therefore it was desirable to have an idea of the risk associated with conducting a repair, where the repair would have to be conducted using an Extra-Vehicular Activity (EVA). Previously, focused analyses had been conducted to quantify the risk associated with certain aspects of an EVA, for example the EVA Mobility Unit (EMU) or Space Suit; however, the analyses were somewhat limited in scope. A complete integrated model of an EVA which could quantify the risk associated with all of the major components of an EVA had never been done before. It was desired to have a complete integrated model to be able to assess the risks associated with an EVA to support the Space Shuttle Program (SSP) in making risk informed decisions. In the case of the HST Servicing Mission, this model was developed to assess specifically the risks associated with performing a TPS repair EVA. This paper provides an overview of the model that was developed to support the HST mission in the event of TPS damage. The HST Servicing Mission was successfully completed on May 24th 2009 with no critical TPS damage; therefore the model was not required for real-time mission support. However, it laid the foundation upon which future EVA quantitative risk assessments could be based.

Extravehicular Space Suit Bearing Technology Development Research

NASA Astrophysics Data System (ADS)

Pang, Yan; Liu, Xiangyang; Guanghui, Xie

2017-03-01

Pressure bearing has been acting an important role in the EVA (extravehicular activity) suit as a main mobility component. EVA suit bearing has its unique traits on the material, dustproof design, seal, interface, lubrication, load and performance. This paper states the peculiarity and development of the pressure bearing on the construction design element, load and failure mode, and performance and test from the point view of structure design. The status and effect of EVA suit pressure bearing is introduced in the paper. This analysis method can provide reference value for our country’s EVA suit pressure bearing design and development.

[Radiation effect on cosmonauts during extravehicular activities in 2008-2009].

PubMed

Mitrikas, V G

2010-01-01

The geometrical model of suited cosmonaut's phantom was used in mathematical modeling of EVAs performed by cosmonauts with consideration of changes in the ISS Russian segment configuration during 2008-2009 and the dependence of space radiation absorbed dose on EVA scene. Influence of spatial position of cosmonaut on absorbed dose value was evaluated with the EVA dosimeter model reproducing the actually determined weight and dimension. Calculated absorbed dose values are in good agreement with experimental data. Absorbed doses imparted to body organs (skin, lens, hemopoietic system, gastrointestinal tract, central nervous system, gonads) were determined for specific EVA events.

PLRP-3: Operational Perspectives of Conducting Science-Driven Extravehicular Activity with Communications Latency

NASA Technical Reports Server (NTRS)

Miller, Matthew J.; Lim, Darlene S. S.; Brady, Allyson; Cardman, Zena; Bell, Ernest; Garry, Brent; Reid, Donnie; Chappell, Steve; Abercromby, Andrew F. J.

2016-01-01

The Pavilion Lake Research Project (PLRP) is a unique platform where the combination of scientific research and human space exploration concepts can be tested in an underwater spaceflight analog environment. The 2015 PLRP field season was performed at Pavilion Lake, Canada, where science-driven exploration techniques focusing on microbialite characterization and acquisition were evaluated within the context of crew and robotic extravehicular activity (EVA) operations. The primary objectives of this analog study were to detail the capabilities, decision-making process, and operational concepts required to meet non-simulated scientific objectives during 5-minute one-way communication latency utilizing crew and robotic assets. Furthermore, this field study served as an opportunity build upon previous tests at PLRP, NASA Desert Research and Technology Studies (DRATS), and NASA Extreme Environment Mission Operations (NEEMO) to characterize the functional roles and responsibilities of the personnel involved in the distributed flight control team and identify operational constraints imposed by science-driven EVA operations. The relationship and interaction between ground and flight crew was found to be dependent on the specific scientific activities being addressed. Furthermore, the addition of a second intravehicular operator was found to be highly enabling when conducting science-driven EVAs. Future human spaceflight activities will need to cope with the added complexity of dynamic and rapid execution of scientific priorities both during and between EVA execution to ensure scientific objectives are achieved.

Effect of oxidation agent on wood biomass in ethylene vinyl acetate conductive polymer: tensile properties, tensile fracture surface and electrical properties

NASA Astrophysics Data System (ADS)

Hanif, M. P. M.; Supri, A. G.; Rozyanty, A. R.; Tan, S. J.

2017-10-01

The wood fiber (WF) type of Pulverised Wood Filler obtained by combustion process at temperature under 700 °C for 3 hours was characterized and coated with ferric chloride (FeCl3) by ethanol solution. Both carbonized wood fiber (CWF) and carbonized wood fiber-ferric chloride (CWF-FeCl3) were used as filler in ethylene vinyl acetate (EVA) conductive polymer. The filler was coated with FeCl3 to enhance the properties of the CWF to achieve progressive mechanical and electrical properties. The CWF and CWF-FeCl3 loading were varied from 2.5 to 10.0 wt%. EVA/CWF and EVA/CWF-FeCl3 conductive polymer were processed by using Brabender Plasticoder at 160 °C with 50 rpm rotor speed for 10 min. The mechanical properties were investigated by tensile testing and the tensile fractured surface of conductive polymers was analyzed by scanning electron microscopy (SEM) analysis. Then, the electrical conductivity of conductive polymer was determined by four-point probe I-V measurement system. The EVA/CWF-FeCl3 conductive polymer showed greater electrical conductivity and tensile strength but lower elongation at break than EVA/CWF conductive polymer. SEM morphology displayed rougher surface between CWF-FeCl3 and EVA phases compared to EVA/CWF conductive polymer.

Extravehicular activities limitations study. Volume 1: Physiological limitations to extravehicular activity in space

NASA Technical Reports Server (NTRS)

Furr, Paul A.; Monson, Conrad B.; Santoro, Robert L.; Sears, William J.; Peterson, Donald H.; Smith, Malcolm

1988-01-01

This report contains the results of a comprehensive literature search on physiological aspects of EVA. Specifically, the topics covered are: (1) Oxygen levels; (2) Optimum EVA work; (3) Food and Water; (4) Carbon dioxide levels; (5) Repetitive decompressions; (6) Thermal, and (7) Urine collection. The literature was assessed on each of these topics, followed by statements on conclusions and recommended future research needs.

Validation of the Long- and Short-Form of the Ethical Values Assessment (EVA): A Questionnaire Measuring the Three Ethics Approach to Moral Psychology

ERIC Educational Resources Information Center

Padilla-Walker, Laura Maria; Jensen, Lene Arnett

2016-01-01

Moral psychology has been moving toward consideration of multiple kinds of moral concepts and values, such as the Ethics of Autonomy, Community, and Divinity. While these three ethics have commonly been measured qualitatively, the current study sought to validate the long and short forms of the Ethical Values Assessment (EVA), which is a…

Genetic Characterization of Enterovirus A71 Circulating in Africa.

PubMed

Fernandez-Garcia, Maria Dolores; Volle, Romain; Joffret, Marie-Line; Sadeuh-Mba, Serge Alain; Gouandjika-Vasilache, Ionela; Kebe, Ousmane; Wiley, Michael R; Majumdar, Manasi; Simon-Loriere, Etienne; Sakuntabhai, Anavaj; Palacios, Gustavo; Martin, Javier; Delpeyroux, Francis; Ndiaye, Kader; Bessaud, Maël

2018-04-01

We analyzed whole-genome sequences of 8 enterovirus A71 isolates (EV-A71). We confirm the circulation of genogroup C and the new genogroup E in West Africa. Our analysis demonstrates wide geographic circulation and describes genetic exchanges between EV-A71 and autochthonous EV-A that might contribute to the emergence of pathogenic lineages.

Genetic Characterization of Enterovirus A71 Circulating in Africa

PubMed Central

Volle, Romain; Joffret, Marie-Line; Sadeuh-Mba, Serge Alain; Gouandjika-Vasilache, Ionela; Kebe, Ousmane; Wiley, Michael R.; Majumdar, Manasi; Simon-Loriere, Etienne; Sakuntabhai, Anavaj; Palacios, Gustavo; Martin, Javier; Delpeyroux, Francis; Ndiaye, Kader; Bessaud, Maël

2018-01-01

We analyzed whole-genome sequences of 8 enterovirus A71 isolates (EV-A71). We confirm the circulation of genogroup C and the new genogroup E in West Africa. Our analysis demonstrates wide geographic circulation and describes genetic exchanges between EV-A71 and autochthonous EV-A that might contribute to the emergence of pathogenic lineages. PMID:29553325

Activity during first EVA of STS-72 mission

NASA Image and Video Library

1996-01-15

STS072-305-034 (15 Jan. 1996) --- Astronaut Daniel T. Barry, mission specialist, works in the cargo bay of the Space Shuttle Endeavour during the first of two extravehicular activities (EVA). Barry was joined by astronaut Leroy Chiao for the EVA. The two joined four other NASA astronauts for a week and a half aboard Endeavour.

Space Shuttle Projects

NASA Image and Video Library

1994-09-16

Astronaut Mark Lee floats freely as he tests the new backpack called the Simplified Aid for EVA Rescue (SAFER) system. SAFER is designed for use in the event a crew member becomes untethered while conducting an EVA. The STS-64 mission marked the first untethered U.S. EVA in 10 years, and was launched on September 9, 1994, aboard the Space Shuttle Orbiter Discovery.

Exploratory Visual Analysis of Statistical Results from Microarray Experiments Comparing High and Low Grade Glioma

PubMed Central

Reif, David M.; Israel, Mark A.; Moore, Jason H.

2007-01-01

The biological interpretation of gene expression microarray results is a daunting challenge. For complex diseases such as cancer, wherein the body of published research is extensive, the incorporation of expert knowledge provides a useful analytical framework. We have previously developed the Exploratory Visual Analysis (EVA) software for exploring data analysis results in the context of annotation information about each gene, as well as biologically relevant groups of genes. We present EVA as a flexible combination of statistics and biological annotation that provides a straightforward visual interface for the interpretation of microarray analyses of gene expression in the most commonly occuring class of brain tumors, glioma. We demonstrate the utility of EVA for the biological interpretation of statistical results by analyzing publicly available gene expression profiles of two important glial tumors. The results of a statistical comparison between 21 malignant, high-grade glioblastoma multiforme (GBM) tumors and 19 indolent, low-grade pilocytic astrocytomas were analyzed using EVA. By using EVA to examine the results of a relatively simple statistical analysis, we were able to identify tumor class-specific gene expression patterns having both statistical and biological significance. Our interactive analysis highlighted the potential importance of genes involved in cell cycle progression, proliferation, signaling, adhesion, migration, motility, and structure, as well as candidate gene loci on a region of Chromosome 7 that has been implicated in glioma. Because EVA does not require statistical or computational expertise and has the flexibility to accommodate any type of statistical analysis, we anticipate EVA will prove a useful addition to the repertoire of computational methods used for microarray data analysis. EVA is available at no charge to academic users and can be found at http://www.epistasis.org. PMID:19390666

Minimizing EVA Airlock Time and Depress Gas Losses

NASA Technical Reports Server (NTRS)

Trevino, Luis A.; Lafuse, Sharon A.

2008-01-01

This paper describes the need and solution for minimizing EVA airlock time and depress gas losses using a new method that minimizes EVA out-the-door time for a suited astronaut and reclaims most of the airlock depress gas. This method consists of one or more related concepts that use an evacuated reservoir tank to store and reclaim the airlock depress gas. The evacuated tank can be an inflatable tank, a spent fuel tank from a lunar lander descent stage, or a backup airlock. During EVA airlock operations, the airlock and reservoir would be equalized at some low pressure, and through proper selection of reservoir size, most of the depress gas would be stored in the reservoir for later reclamation. The benefit of this method is directly applicable to long duration lunar and Mars missions that require multiple EVA missions (up to 100, two-person lunar EVAs) and conservation of consumables, including depress pump power and depress gas. The current ISS airlock gas reclamation method requires approximately 45 minutes of the astronaut s time in the airlock and 1 KW in electrical power. The proposed method would decrease the astronaut s time in the airlock because the depress gas is being temporarily stored in a reservoir tank for later recovery. Once the EVA crew is conducting the EVA, the volume in the reservoir would be pumped back to the cabin at a slow rate. Various trades were conducted to optimize this method, which include time to equalize the airlock with the evacuated reservoir versus reservoir size, pump power to reclaim depress gas versus time allotted, inflatable reservoir pros and cons (weight, volume, complexity), and feasibility of spent lunar nitrogen and oxygen tanks as reservoirs.

Near Real Time Tools for ISS Plasma Science and Engineering Applications

NASA Astrophysics Data System (ADS)

Minow, J. I.; Willis, E. M.; Parker, L. N.; Shim, J.; Kuznetsova, M. M.; Pulkkinen, A. A.

2013-12-01

The International Space Station (ISS) program utilizes a plasma environment forecast for estimating electrical charging hazards for crews during extravehicular activity (EVA). The process uses ionospheric electron density and temperature measurements from the ISS Floating Potential Measurement Unit (FPMU) instrument suite with the assumption that the plasma conditions will remain constant for one to fourteen days with a low probability for a space weather event which would significantly change the environment before an EVA. FPMU data is typically not available during EVA's, therefore, the most recent FPMU data available for characterizing the state of the ionosphere during EVA is typically a day or two before the start of an EVA or after the EVA has been completed. In addition to EVA support, information on ionospheric plasma densities is often needed for support of ISS science payloads and anomaly investigations during periods when the FPMU is not operating. This presentation describes the application of space weather tools developed by MSFC using data from near real time satellite radio occultation and ground based ionosonde measurements of ionospheric electron density and a first principle ionosphere model providing electron density and temperature run in a real time mode by GSFC. These applications are used to characterize the space environment during EVA periods when FPMU data is not available, monitor for large charges in ionosphere density that could render the ionosphere forecast and plasma hazard assessment invalid, and validate the assumption of 'persistence of conditions' used in deriving the hazard forecast. In addition, the tools are used to provide space environment input to science payloads on ISS and anomaly investigations during periods the FPMU is not operating.

EVA-Compatible Microbial Swab Tool

NASA Technical Reports Server (NTRS)

Rucker, Michelle A.

2016-01-01

When we send humans to search for life on Mars, we'll need to know what we brought with us versus what may already be there. To ensure our crewed spacecraft meet planetary protection requirements—and to protect our science from human contamination—we'll need to know whether micro-organisms are leaking/venting from our ships and spacesuits. This is easily done by swabbing external vents and suit surfaces for analysis, but requires a specialized tool for the job. Engineers at the National Aeronautics and Space Administration (NASA) recently developed an Extravehicular Activity (EVA)-compatible swab tool that can be used to sample current space suits and life support systems. Data collected now will influence Mars life support and EVA hardware early in the planning process, before design changes become difficult and expensive.NASA’s EVA swab tool pairs a Space Shuttle-era tool handle with a commercially available swab tip mounted into a custom-designed end effector. A glove-compatible release mechanism allows the handle to quickly switch between swab tips, much like a shaving razor handle can snap onto a disposable blade cartridge. Swab tips are stowed inside individual sterile containers, each fitted with a microbial filter that allows the container to equalize atmospheric pressure, but prevents cabin contaminants from rushing into the container when passing from the EVA environment into a pressurized cabin. A bank of containers arrayed inside a tool caddy allows up to six individual samples to be collected during a given spacewalk.NASA plans to use the tool in 2016 to collect samples from various spacesuits during ground testing to determine what (if any) human-borne microbial contamination leaks from the suit under simulated thermal vacuum conditions. Next, the tool will be used on board the International Space Station to assess the types of microbial contaminants found on external environmental control and life support system vents. Data will support advanced EVA and life support system maturation studies, helping to answer questions such as “how close can an EVA-suited crew member approach an area of scientific interest without compromising the science?”

A rapidly equilibrating, thin film, passive water sampler for organic contaminants; characterization and field testing.

PubMed

St George, Tiffany; Vlahos, Penny; Harner, Tom; Helm, Paul; Wilford, Bryony

2011-02-01

Improving methods for assessing the spatial and temporal resolution of organic compound concentrations in marine environments is important to the sustainable management of our coastal systems. Here we evaluate the use of ethylene vinyl acetate (EVA) as a candidate polymer for thin-film passive sampling in waters of marine environments. Log K(EVA-W) partition coefficients correlate well (r(2) = 0.87) with Log K(OW) values for selected pesticides and polychlorinated biphenyls (PCBs) where Log K(EVA-W) = 1.04 Log K(OW) + 0.22. EVA is a suitable polymer for passive sampling due to both its high affinity for organic compounds and its ease of coating at sub-micron film thicknesses on various substrates. Twelve-day field deployments were effective in detecting target compounds with good precision making EVA a potential multi-media fugacity meter. Published by Elsevier Ltd.

The micro conical system: Lessons learned from a successful EVA/robot-compatible mechanism

NASA Technical Reports Server (NTRS)

Gittleman, Mark; Johnston, Alistair

1996-01-01

The Micro Conical System (MCS) is a three-part, multi-purpose mechanical interface system used for acquiring and manipulating masses on-orbit by either extravehicular activity (EVA) or telerobotic means. The three components of the system are the micro conical fitting (MCF), the EVA micro tool (EMCT), and the Robot Micro Conical Tool (RMCT). The MCS was developed and refined over a four-year period. This period culminated with the delivery of 358 Class 1 and Class 2 micro conical fittings for the International Space Station and with its first use in space to handle a 1272 kg (2800 lbm) Spartan satellite (11000 times greater than the MCF mass) during an EVA aboard STS-63 in February, 1995. The micro conical system is the first successful EVA/robot-compatible mechanism to be demonstrated in the external environment aboard the U.S. Space Shuttle.

Human Space Exploration and Radiation Exposure from EVA: 1981-2011

NASA Astrophysics Data System (ADS)

Way, A. R.; Saganti, S. P.; Erickson, G. M.; Saganti, P. B.

2011-12-01

There are several risks for any human space exploration endeavor. One such inevitable risk is exposure to the space radiation environment of which extra vehicular activity (EVA) demands more challenges due to limited amount of protection from space suit shielding. We recently compiled all EVA data comprising low-earth orbit (LEO) from Space Shuttle (STS) flights, International Space Station (ISS) expeditions, and Shuttle-Mir missions. Assessment of such radiation risk is very important, particularly for the anticipated long-term, deep-space human explorations in the near future. We present our assessment of anticipated radiation exposure and space radiation dose contribution to each crew member from a listing of 350 different EVA events resulting in more than 1000+ hrs of total EVA time. As of July 12, 2011, 197 astronauts have made spacewalks (out of 520 people who have gone into Earth orbit). Only 11 women have been on spacewalks.

A simulation system for Space Station extravehicular activity

NASA Technical Reports Server (NTRS)

Marmolejo, Jose A.; Shepherd, Chip

1993-01-01

America's next major step into space will be the construction of a permanently manned Space Station which is currently under development and scheduled for full operation in the mid-1990's. Most of the construction of the Space Station will be performed over several flights by suited crew members during an extravehicular activity (EVA) from the Space Shuttle. Once fully operational, EVA's will be performed from the Space Station on a routine basis to provide, among other services, maintenance and repair operations of satellites currently in Earth orbit. Both voice recognition and helmet-mounted display technologies can improve the productivity of workers in space by potentially reducing the time, risk, and cost involved in performing EVA. NASA has recognized this potential and is currently developing a voice-controlled information system for Space Station EVA. Two bench-model helmet-mounted displays and an EVA simulation program have been developed to demonstrate the functionality and practicality of the system.

High-Pressure Oxygen Generation for Outpost EVA Study

NASA Technical Reports Server (NTRS)

Jeng, Frank F.; Conger, Bruce; Ewert, Michael K.; Anderson, Molly S.

2009-01-01

The amount of oxygen consumption for crew extravehicular activity (EVA) in future lunar exploration missions will be significant. Eight technologies to provide high pressure EVA O2 were investigated. They are: high pressure O2 storage, liquid oxygen (LOX) storage followed by vaporization, scavenging LOX from Lander followed by vaporization, LOX delivery followed by sorption compression, water electrolysis followed by compression, stand-alone high pressure water electrolyzer, Environmental Control and Life Support System (ECLSS) and Power Elements sharing a high pressure water electrolyzer, and ECLSS and In-Situ Resource Utilization (ISRU) Elements sharing a high pressure electrolyzer. A trade analysis was conducted comparing launch mass and equivalent system mass (ESM) of the eight technologies in open and closed ECLSS architectures. Technologies considered appropriate for the two architectures were selected and suggested for development.

Study of EVA operations associated with satellite services

NASA Technical Reports Server (NTRS)

Nash, J. O.; Wilde, R. D.

1982-01-01

Extravehicular mobility unit (EMU) factors associated with satellite servicing activities are identified and the EMU improvements necessary to enhance satellite servicing operations are outlined. Areas of EMU capabilities, equipment and structural interfaces, time lines, EMU modifications for satellite servicing, environmental hazards, and crew training are vital to manned Eva/satellite services and as such are detailed. Evaluation of EMU capabilities indicates that the EMU can be used in performing near term, basic satellite servicing tasks; however, satellite servicing is greatly enhanced by incorporating key modifications into the EMU. The servicing missions involved in contamination sensitive payload repair are illustrated. EVA procedures and equipment can be standardized, reducing both crew training time and in orbit operations time. By standardizing and coordinating procedures, mission cumulative time lines fall well within the EMU capability.

Influences of modified bacterial cellulose nanofibers (BCNs) on structural, thermophysical, optical, and barrier properties of poly ethylene-co-vinyl acetate (EVA) nanocomposite.

PubMed

Ghadikolaei, Shila Shirdel; Omrani, Abdollah; Ehsani, Morteza

2018-04-14

The BCNs were chemically modified using acetic anhydride with the aim of improving its dispersion and interfacial adhesion. Acetylation of BCNs was confirmed by FT-IR spectroscopy. Morphology studies using TEM and SEM revealed that a reasonable dispersion of the modified BCNs in the EVA matrix was accomplished. The DSC data displayed a little shift in the T g to higher temperatures with the incorporation of both modified and unmodified BCNs. Increased thermal stability of the nanocomposites consisting acetylated BCNs was confirmed by TGA technique. DMA measurements highlighted that the storage modulus increased and the damping properties decreased for the nanocomposites with regard to the neat EVA. Copyright © 2018 Elsevier B.V. All rights reserved.

Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

NASA Technical Reports Server (NTRS)

Mitchell, Kathryn

2009-01-01

During the Apollo program, the space suit outer layer fabrics were severely abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub-layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, shares the results of the testing, and provides recommendations for future work.

Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

NASA Technical Reports Server (NTRS)

Mitchell, Kathryn C.

2010-01-01

During the Apollo program, the space suit outer layer fabrics were badly abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub -layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This Paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, and shares the results and conclusions of the testing.

The use of decompression to simulate the effect of extravehicular activity on human lymphocyte transformation

NASA Technical Reports Server (NTRS)

Meehan, R. T.; Duncan, U.; Neale, L.; Waligora, J.; Taylor, G. R.

1986-01-01

Lymphocytes from 35 subjects participating in a chamber study simulating extravehicular activity (EVA) conditions were studied. No significant differences in H3 thymidine uptake between pre chamber and post chamber response to any mitogens autologous plasma, or among circulating mononuclear cells by flow cytometry are observed. The studies could not identify the subjects who developed venous bubbles. Data from eight subjects suggests that acute stress associated with participating in the study augments in vitro lymphocyte proliferation. Results indicate EVA exposure does not greatly influence space-flight induced alterations in immune effector cell function.

Astronaut Carl Walz during EVA in Discovery's payload bay

NASA Technical Reports Server (NTRS)

1993-01-01

Astronaut Carl E. Walz reaches for equipment from the provisional stowage assembly (PSA) in Discvoery's cargo bay during a lengthy period of extravehicular activity (EVA). The hatch to Discovery's airlock is open nearby. Sun glare is evident above the orbiter. The picture was taken with a 35mm camera by astronaut James H. Newman, who shared EVA duties with Walz.

Second-Order Learning and Education for Peace: Eva Nordland and the Project "Preparedness for Peace." Peace Education Miniprints No. 54.

ERIC Educational Resources Information Center

Bjerstedt, Ake

This interview explores the views of Eva Norland, an educational researcher and peace activist. A discussion of peace education examines definitions, school contribution, age levels, teacher training, and instructional approach. Eva Norland offers her opinion on the concept of peace from environmental development, solidarity work, human rights,…

STS-49 MS Akers handles strut during ASEM procedures in OV-105's payload bay

NASA Image and Video Library

1992-05-14

STS049-77-028 (14 May 1992) --- Astronaut Thomas D. Akers, STS-49 mission specialist, grabs a strut device as fourth period of extravehicular activity (EVA) gets underway in the Space Shuttle Endeavour's cargo bay. Akers is positioned near the Multi-purpose Support Structure (MPESS). The purpose of the final EVA on this nine-day mission was the evaluation of Assembly of Station by EVA Methods (ASEM). The scene was recorded on 70mm film by a fellow crew member in the space shuttle's cabin. Astronaut Kathryn C. Thornton (out of frame) joined Akers on the 7 1/2 hour EVA.

Photovoltaics module interface: General purpose primers

NASA Technical Reports Server (NTRS)

Boerio, J.

1985-01-01

The interfacial chemistry established between ethylene vinyl acetate (EVA) and the aluminized back surface of commercial solar cells was observed experimentally. The technique employed is called Fourier Transform Infrared (FTIR) spectroscopy, with the infrared signal being reflected back from the aluminum surface through the EVA film. Reflection infrared (IR) spectra are given and attention is drawn to the specific IR peak at 1080/cm which forms on hydrolytic aging of the EVA/aluminum system. With this fundamental finding, and the workable experimental techniques, candidate silane coupling agents are employed at the interface, and their effects on eliminating or slowing hydrolytic aging of the EVA/aluminum interface are monitored.

Extravehicular Activity (EVA) Microbial Swab Tool

NASA Technical Reports Server (NTRS)

Rucker, Michelle

2015-01-01

When we send humans to search for life on Mars, we'll need to know what we brought with us versus what may already be there. To ensure our crewed spacecraft meet planetary protection requirements--and to protect our science from human contamination--we'll need to know whether micro-organisms are leaking/venting from our ships and spacesuits. This is easily done by swabbing external vents and surfaces for analysis, but there was no US EVA tool for that job. NASA engineers developed an EVA-compatible swab tool that can be used to collect data on current hardware, which will influence eventual Mars life support and EVA hardware designs.

Human-Centric Teaming in a Multi-Agent EVA Assembly Task

NASA Technical Reports Server (NTRS)

Rehnmark, Fredrik; Currie, Nancy; Ambrose, Robert O.; Culbert, Christopher

2004-01-01

NASA's Human Space Flight program depends heavily on spacewalks performed by pairs of suited human astronauts. These Extra-Vehicular Activities (EVAs) are severely restricted in both duration and scope by consumables and available manpower.An expanded multi-agent EVA team combining the information-gathering and problem-solving skills of human astronauts with the survivability and physical capabilities of highly dexterous space robots is proposed. A 1-g test featuring two NASA/DARPA Robonaut systems working side-by-side with a suited human subject is conducted to evaluate human-robot teaming strategies in the context of a simulated EVA assembly task based on the STS-61B ACCESS flight experiment.

Changes in the EV-A71 Genome through Recombination and Spontaneous Mutations: Impact on Virulence.

PubMed

Mandary, Madiiha Bibi; Poh, Chit Laa

2018-06-12

Enterovirus 71 (EV-A71) is a major etiological agent of hand, foot and mouth disease (HFMD) that mainly affects young children less than five years old. The onset of severe HFMD is due to neurological complications bringing about acute flaccid paralysis and pulmonary oedema. In this review, we address how genetic events such as recombination and spontaneous mutations could change the genomic organization of EV-A71, leading to an impact on viral virulence. An understanding of the recombination mechanism of the poliovirus and non-polio enteroviruses will provide further evidence of the emergence of novel strains responsible for fatal HFMD outbreaks. We aim to see if the virulence of EV-A71 is contributed solely by the presence of fatal strains or is due to the co-operation of quasispecies within a viral population. The phenomenon of quasispecies within the poliovirus is discussed to reflect viral fitness, virulence and its implications for EV-A71. Ultimately, this review gives an insight into the evolution patterns of EV-A71 by looking into its recombination history and how spontaneous mutations would affect its virulence.

Development of an Extra-vehicular (EVA) Infrared (IR) Camera Inspection System

NASA Technical Reports Server (NTRS)

Gazarik, Michael; Johnson, Dave; Kist, Ed; Novak, Frank; Antill, Charles; Haakenson, David; Howell, Patricia; Pandolf, John; Jenkins, Rusty; Yates, Rusty

2006-01-01

Designed to fulfill a critical inspection need for the Space Shuttle Program, the EVA IR Camera System can detect crack and subsurface defects in the Reinforced Carbon-Carbon (RCC) sections of the Space Shuttle s Thermal Protection System (TPS). The EVA IR Camera performs this detection by taking advantage of the natural thermal gradients induced in the RCC by solar flux and thermal emission from the Earth. This instrument is a compact, low-mass, low-power solution (1.2cm3, 1.5kg, 5.0W) for TPS inspection that exceeds existing requirements for feature detection. Taking advantage of ground-based IR thermography techniques, the EVA IR Camera System provides the Space Shuttle program with a solution that can be accommodated by the existing inspection system. The EVA IR Camera System augments the visible and laser inspection systems and finds cracks and subsurface damage that is not measurable by the other sensors, and thus fills a critical gap in the Space Shuttle s inspection needs. This paper discusses the on-orbit RCC inspection measurement concept and requirements, and then presents a detailed description of the EVA IR Camera System design.

Real-Time EVA Troubleshooting

NASA Technical Reports Server (NTRS)

Parazynski, Scott

2012-01-01

Dr. Parazynski focused on the Shuttle Transportation System (STS)-120 Solar Array Repair Extravehicular Activity (EVA) with personal anecdotes and then spoke about what it takes to have a successful EVA during the event, what types of problems can occur during an EVA, particularly with the spacesuit and the safety of the crew, and how to resolve these quickly, safely, and efficiently. He also described the participants and the types of decisions and actions each had to take to ensure success. He described "Team 4," in Houston and on-orbit, as well as anecdotes from his STS-86 and STS-100 missions. Parazynski provided a retrospective on the EVA tools and procedures NASA used in the aftermath of Columbia for shuttle Thermal Protection System (TPS) inspection and repair. He described his role as the lead astronaut during this effort, and covered all the Neutral Buoyancy Laboratory (NBL), KC-135, precision air-bearing floor (PABF), vacuum chamber, and 1-G testing performed to develop the tools and techniques that were flown. Parazynski discussed how the EVA community worked together to resolve a huge safety issue, and how his work in the spacesuit was critical to overcoming a design limitation of the Space Shuttle.

Evaluation of safety of hypobaric decompressions and EVA from positions of probabilistic theory

NASA Astrophysics Data System (ADS)

Nikolaev, V. P.

Formation and subsequent evolution of gas bubbles in blood and tissues of subjects exposed to decompression are casual processes in their nature. Such character of bubbling processes in a body predetermines probabilistic character of decompression sickness (DCS) incidence in divers, aviators and astronauts. Our original probabilistic theory of decompression safety is based on stochastic models of these processes and on the concept of critical volume of a free gas phase in body tissues. From positions of this theory, the probability of DCS incidence during single-stage decompressions and during hypobaric decompressions under EVA in particular, is defined by the distribution of possible values of nucleation efficiency in "pain" tissues and by its critical significance depended on the parameters of a concrete decompression. In the present study the following is shown: 1) the dimensionless index of critical nucleation efficiency for "pain" body tissues is a more adequate index of decompression stress in comparison with Tissue Ratio, TR; 2) a priory the decompression under EVA performed according to the Russian protocol is more safe than decompression under EVA performed in accordance with the U.S. protocol; 3) the Russian space suit operated at a higher pressure and having a higher "rigidity" induces a stronger inhibition of mechanisms of cavitation and gas bubbles formation in tissues of a subject located in it, and by that provides a more considerable reduction of the DCS risk during real EVA performance.

Results and Lessons Learned from Performance Testing of Humans in Spacesuits in Simulated Reduced Gravity

NASA Technical Reports Server (NTRS)

Chappell, Steven P.; Norcross, Jason R.; Gernhardt, Michael L.

2010-01-01

The Apollo lunar EVA experience revealed challenges with suit stability and control-likely a combination of mass, mobility, and center of gravity (CG) factors. The EVA Physiology, Systems and Performence (EPSP) Project is systematically working with other NASA projects, labs, and facilities to lead a series of studies to understand the role of suit mass, weight, CG, and other parameters on astronaut performance in partial gravity environments.

Near Real Time Tools for ISS Plasma Science and Engineering Applications

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Willis, Emily M.; Parker, Linda Neergaard; Shim, Ja Soon; Kuznetsova, Maria M.; Pulkkinen, Antti, A.

2013-01-01

The International Space Station (ISS) program utilizes a plasma environment forecast for estimating electrical charging hazards for crews during extravehicular activity (EVA). The process uses ionospheric electron density (Ne) and temperature (Te) measurements from the ISS Floating Potential Measurement Unit (FPMU) instrument suite with the assumption that the plasma conditions will remain constant for one to fourteen days with a low probability for a space weather event which would significantly change the environment before an EVA. FPMU data is typically not available during EVA's, therefore, the most recent FPMU data available for characterizing the state of the ionosphere during EVA is typically a day or two before the start of an EVA or after the EVA has been completed. Three near real time space weather tools under development for ISS applications are described here including: (a) Ne from ground based ionosonde measurements of foF2 (b) Ne from near real time satellite radio occultation measurements of electron density profiles (c) Ne, Te from a physics based ionosphere model These applications are used to characterize the ISS space plasma environment during EVA periods when FPMU data is not available, monitor for large changes in ionosphere density that could render the ionosphere forecast and plasma hazard assessment invalid, and validate the "persistence of conditions" forecast assumption. In addition, the tools are useful for providing space environment input to science payloads on ISS and anomaly investigations during periods the FPMU is not operating.

[Use of the EvalObs® adherence scale in an unselected French population of treated subjects with antihypertensive, hypolipemiants or oral antidiabetics medications: The FLAHS 2017 adherence survey].

PubMed

Girerd, X; Hanon, O; Vaïsse, B

2018-06-01

A Visual Analog Scale (VAS) is useful for diagnosing medication nonadherence and its validity has been evaluated using electronic pillbox as the gold standard. We have developed the EvaLobs ® scale for use on paper or on smartphone and the aim of the study was to administrate the scale among FLAHS 2017 participants treated for an hypertension, a dyslipidemia or diabetes. In subjects treated with antihypertensive medications, participants completed the 6-item Girerd Scale and EvaLobs ® . The French League Against Hypertension Survey (FLAHS) are carried out by self-questionnaire sent by mail to individuals from the French Kantar Health sampling frame (representative panel of the population living in metropolitan France). In 2017, FLAHS was conducted in 4783 subjects aged 35 and over. The EvaLobs ® has a scale from 0 to 15 and the use instruction is "how many days have you taken the drug in the past 15 days". A score>12 indicates a "good compliance". The 6-item Girerd scale was also completed. "Good adherence" was determined for a score of 0 to 2 and "nonadherence" for a score of 3 or more. The agreement between EvaLobs ® and the 6-item Girerd scale was evaluated in treated hypertensives. The survey included 4783 subjects with 1308 treated hypertensives, 942 subjects treated with lipid-lowering drugs and 405 subjects treated with anti-diabetics. EVALOBS ® indicates "Good adherence" in 96% of subjects and the 6 questions questionnaire indicates "good adherence" in 95% of subjects. An excellent agreement is noted in 93.8%. An EvaLobs ® score indicating nonadherence or an absence of response to EvaLobs ® is observed in 3.6% [CI 95, 2.5-4.7] of hypertensives, in 6.0% [CI 95, 3.9-8.1] of diabetics and in 8.2% [CI 95, 6.5-9.9] of dyslipidemic patients. In the population living in France and in unselected patients treated for metabolic disease or hypertension, non-adherence is lowest for antihypertensive medications and highest for statins. EvaLobs ® , which shows good agreement with an adherence questionnaire, is a quick and simple tool for assessing adherence. The smartphone app EvaLobs ® is available for free on Google play and the Apple store. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

STS-64 extravehicular activity (EVA) hardware view

NASA Image and Video Library

1993-01-21

S93-26920 (8 Sept. 1994) --- Scott Bleisath, an extravehicular activity (EVA) engineer, demonstrates the hand control module for the Simplified Aid for EVA Rescue (SAFER) system making its first flight on the scheduled September STS-64 mission. Astronauts Mark C. Lee and Carl J. Meade are the spacewalkers assigned to test the system in space. Photo credit: NASA or National Aeronautics and Space Administration

Polyblends of LDPE with EVA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deanin, R.D.; Hou, T.J.A.

1993-12-31

Melt processability of LDPE was improved by blending with EVA copolymers containing 10-28% VA. Softening of modules was controlled primarily by overall VA content of the blends. Tensile necking was converted to smooth rubbery elongation by adding larger amounts of VA. Transparency was produced by adding EVA containing 10% VA and then stretching the polyblend film. These parameters give the film manufacturer wide control over processability and properties.

Astronaut Dale Gardner holds up for sale sign after EVA

NASA Technical Reports Server (NTRS)

1984-01-01

Astronaut Dale A. Gardner, having just completed the major portion of his second extravehicular activity (EVA) period in three days, holds up a 'for sale' sign. Astronaut Joseph P. ALlen IV, who also participated in the two EVA's, is reflected in Gardner's helmet visor. A portion of each of two recovered satellites is in the lower right corner, with Westar nearer Discovery's aft.

New Introductions of Enterovirus 71 Subgenogroup C4 Strains, France, 2012

PubMed Central

Henquell, Cécile; Mirand, Audrey; Coste-Burel, Marianne; Marque-Juillet, Stéphanie; Desbois, Delphine; Lagathu, Gisèle; Bornebusch, Laure; Bailly, Jean-Luc; Lina, Bruno

2014-01-01

In France during 2012, human enterovirus 71 (EV-A71) subgenogroup C4 strains were detected in 4 children hospitalized for neonatal fever or meningitis. Phylogenetic analysis showed novel and independent EV-A71 introductions, presumably from China, and suggested circulation of C4 strains throughout France. This observation emphasizes the need for monitoring EV-A71 infections in Europe. PMID:25061698

Metabolic and Subjective Results Review of the Integrated Suit Test Series

NASA Technical Reports Server (NTRS)

Norcross, J.R.; Stroud, L.C.; Klein, J.; Desantis, L.; Gernhardt, M.L.

2009-01-01

Crewmembers will perform a variety of exploration and construction activities on the lunar surface. These activities will be performed while inside an extravehicular activity (EVA) spacesuit. In most cases, human performance is compromised while inside an EVA suit as compared to a crewmember s unsuited performance baseline. Subjects completed different EVA type tasks, ranging from ambulation to geology and construction activities, in different lunar analog environments including overhead suspension, underwater and 1-g lunar-like terrain, in both suited and unsuited conditions. In the suited condition, the Mark III (MKIII) EVA technology demonstrator suit was used and suit pressure and suit weight were parameters tested. In the unsuited conditions, weight, mass, center of gravity (CG), terrain type and navigation were the parameters. To the extent possible, one parameter was varied while all others were held constant. Tests were not fully crossed, but rather one parameter was varied while all others were left in the most nominal setting. Oxygen consumption (VO2), modified Cooper-Harper (CH) ratings of operator compensation and ratings of perceived exertion (RPE) were measured for each trial. For each variable, a lower value correlates to more efficient task performance. Due to a low sample size, statistical significance was not attainable. Initial findings indicate that suit weight, CG and the operational environment can have a large impact on human performance during EVA. Systematic, prospective testing series such as those performed to date will enable a better understanding of the crucial interactions of the human and the EVA suit system and their environment. However, work remains to be done to confirm these findings. These data have been collected using only unsuited subjects and one EVA suit prototype that is known to fit poorly on a large demographic of the astronaut population. Key findings need to be retested using an EVA suit prototype better suited to a larger anthropometric portion of the astronaut population, and elements tested only in the unsuited condition need to be evaluated with an EVA suit and appropriate analog environment.

Thermal and chemical stabilization of ethylene/vinyl acetate/vinyl alcohol (EVA-OH) terpolymers under nitroplasticizer environments

DOE PAGES

Yang, Dali; Hubbard, Kevin M.; Henderson, Kevin C.; ...

2014-09-17

Here, we compare the aging behaviors of cross-linked ethylene/vinyl acetate/vinyl alcohol terpolymers, also referred to as EVA-OH, when they are either immersed in nitroplasticizer (NP) liquid or exposed to NP vapor at different temperatures. And while thermogravimetric analysis and differential scanning calorimetry are used to probe the thermal stability of aged NP and polymers, Fourier transform infrared, gel permeation chromatography, ultra-violet/vis, and nuclear magnetic resonance are used to probe their structural changes over the aging process. Our study confirms that NP degrades through C[BOND]N cleavage, and releases HONO molecules at a slightly elevated temperature (<75°C). As these molecules accumulate inmore » the vapor phase, they react among themselves to create an acidic environment. Therefore, these chemical constituents in the NP vapor significantly accelerate the hydrolysis of EVA-OH polymer. When the hydrolysis occurs in both vinyl acetate and urethane groups and the scission at the cross-linker progresses, EVA-OH becomes vulnerable to further degradation in the NP vapor environment. Finally, through the comprehensive characterization, the possible degradation mechanisms of the terpolymers are proposed.« less

Verification of a Viscous Computational Aeroacoustics Code using External Verification Analysis

NASA Technical Reports Server (NTRS)

Ingraham, Daniel; Hixon, Ray

2015-01-01

The External Verification Analysis approach to code verification is extended to solve the three-dimensional Navier-Stokes equations with constant properties, and is used to verify a high-order computational aeroacoustics (CAA) code. After a brief review of the relevant literature, the details of the EVA approach are presented and compared to the similar Method of Manufactured Solutions (MMS). Pseudocode representations of EVA's algorithms are included, along with the recurrence relations needed to construct the EVA solution. The code verification results show that EVA was able to convincingly verify a high-order, viscous CAA code without the addition of MMS-style source terms, or any other modifications to the code.

Verification of a Viscous Computational Aeroacoustics Code Using External Verification Analysis

NASA Technical Reports Server (NTRS)

Ingraham, Daniel; Hixon, Ray

2015-01-01

The External Verification Analysis approach to code verification is extended to solve the three-dimensional Navier-Stokes equations with constant properties, and is used to verify a high-order computational aeroacoustics (CAA) code. After a brief review of the relevant literature, the details of the EVA approach are presented and compared to the similar Method of Manufactured Solutions (MMS). Pseudocode representations of EVA's algorithms are included, along with the recurrence relations needed to construct the EVA solution. The code verification results show that EVA was able to convincingly verify a high-order, viscous CAA code without the addition of MMS-style source terms, or any other modifications to the code.

The impact of electron beam irradiation on Low density polyethylene and Ethylene vinyl acetate

NASA Astrophysics Data System (ADS)

Sabet, Maziyar; Soleimani, Hassan

2017-05-01

Improvement of measured gel content, hardness, tensile strength and elongation at break of Ethylene vinyl acetate (EVA) have confirmed positive effect of electron beam irradiation on EVA. Results obtained from both gel content tests show that degree of cross-linking in amorphous regions is dependent on dose. A significant improvement in tensile strength of neat EVA samples is obtained upon electron-beam radiation up to 210 kGy. Similarly, hardness properties of Low-density polyethylene (LDPE) improvewith increasing electron beam irradiation. This article deals with the impacts of electron beam (EB) irradiation on the properties of LDPE and Ethylene-Vinyl Acetate (EVA) as the two common based formulations for wire and cable applications.

Applications of ethylene vinyl acetate copolymers (EVA) in drug delivery systems.

PubMed

Schneider, Christian; Langer, Robert; Loveday, Donald; Hair, Dirk

2017-09-28

The potential for use of polymers in controlled drug delivery systems has been long recognized. Since their appearance in the literature, a wide range of degradable and non-degradable polymers have been demonstrated in drug delivery devices. The significance and features of ethylene-vinyl acetate (EVA) copolymers in initial research and development led to commercial drug delivery systems. This review examines the breadth of EVA use in drug delivery, and will aid the researcher in locating key references and experimental results, as well as understanding the features of EVA as a highly versatile, biocompatible polymer for drug delivery devices. Topics will include. Copyright © 2017 Elsevier B.V. All rights reserved.

The Epidemiology of Hand, Foot and Mouth Disease in Asia

PubMed Central

Koh, Wee Ming; Bogich, Tiffany; Siegel, Karen; Jin, Jing; Chong, Elizabeth Y.; Tan, Chong Yew; Chen, Mark IC; Horby, Peter

2016-01-01

Context: Hand, foot and mouth disease (HFMD) is a widespread pediatric disease caused primarily by human enterovirus 71 (EV-A71) and Coxsackievirus A16 (CV-A16). Objective: This study reports a systematic review of the epidemiology of HFMD in Asia. Data Sources: PubMed, Web of Science and Google Scholar were searched up to December 2014. Study Selection: Two reviewers independently assessed studies for epidemiologic and serologic information about prevalence and incidence of HFMD against predetermined inclusion/exclusion criteria. Data Extraction: Two reviewers extracted answers for 8 specific research questions on HFMD epidemiology. The results are checked by 3 others. Results: HFMD is found to be seasonal in temperate Asia with a summer peak and in subtropical Asia with spring and fall peaks, but not in tropical Asia; evidence of a climatic role was identified for temperate Japan. Risk factors for HFMD include hygiene, age, gender and social contacts, but most studies were underpowered to adjust rigorously for confounding variables. Both community-level and school-level transmission have been implicated, but their relative importance for HFMD is inconclusive. Epidemiologic indices are poorly understood: No supporting quantitative evidence was found for the incubation period of EV-A71; the symptomatic rate of EV-A71/Coxsackievirus A16 infection was from 10% to 71% in 4 studies; while the basic reproduction number was between 1.1 and 5.5 in 3 studies. The uncertainty in these estimates inhibits their use for further analysis. Limitations: Diversity of study designs complicates attempts to identify features of HFMD epidemiology. Conclusions: Knowledge on HFMD remains insufficient to guide interventions such as the incorporation of an EV-A71 vaccine in pediatric vaccination schedules. Research is urgently needed to fill these gaps. PMID:27273688

NEEMO 14: Evaluation of Human Performance for Rover, Cargo Lander, Crew Lander, and Exploration Tasks in Simulated Partial Gravity

NASA Technical Reports Server (NTRS)

Chappell, Steven P.; Abercromby, Andrew F.; Gernhardt, Michael L.

2011-01-01

The ultimate success of future human space exploration missions is dependent on the ability to perform extravehicular activity (EVA) tasks effectively, efficiently, and safely, whether those tasks represent a nominal mode of operation or a contingency capability. To optimize EVA systems for the best human performance, it is critical to study the effects of varying key factors such as suit center of gravity (CG), suit mass, and gravity level. During the 2-week NASA Extreme Environment Mission Operations (NEEMO) 14 mission, four crewmembers performed a series of EVA tasks under different simulated EVA suit configurations and used full-scale mockups of a Space Exploration Vehicle (SEV) rover and lander. NEEMO is an underwater spaceflight analog that allows a true mission-like operational environment and uses buoyancy effects and added weight to simulate different gravity levels. Quantitative and qualitative data collected during NEEMO 14, as well as from spacesuit tests in parabolic flight and with overhead suspension, are being used to directly inform ongoing hardware and operations concept development of the SEV, exploration EVA systems, and future EVA suits. OBJECTIVE: To compare human performance across different weight and CG configurations. METHODS: Four subjects were weighed out to simulate reduced gravity and wore either a specially designed rig to allow adjustment of CG or a PLSS mockup. Subjects completed tasks including level ambulation, incline/decline ambulation, standing from the kneeling and prone position, picking up objects, shoveling, ladder climbing, incapacitated crewmember handling, and small and large payload transfer. Subjective compensation, exertion, task acceptability, and duration data as well as photo and video were collected. RESULTS: There appear to be interactions between CG, weight, and task. CGs nearest the subject s natural CG are the most predictable in terms of acceptable performance across tasks. Future research should focus on understanding the interactions between CG, mass, and subject differences.

FY13 High Performance EVA Glove (HPEG) Collaboration: Glove Injury Data Mining Effort - Training Data Overview

NASA Technical Reports Server (NTRS)

Reid, Christopher; Benson, Elizabeth; England, Scott; Charvat, Jacqueline; Norcross, Jason; McFarland, Shane; Rajulu, Sudhakar

2014-01-01

From the time hand-intensive tasks were first created for EVAs, discomforts and injuries have been noted.. There have been numerous versions of EVA gloves for US crew over the past 50 years, yet pain and injuries persist. The investigation team was tasked with assisting in a glove injury assessment for the High Performance EVA Glove (HPEG) project.center dot To aid in this assessment, the team was asked to complete the following objectives: - First, to develop the best current understanding of what glove-related injuries have occurred to date, and when possible, identify the specific mechanisms that caused those injuries - Second, to create a standardized method for comparison of glove injury potential from one glove to another. center dot The overall goal of the gloved hand injury assessment is to utilize ergonomics in understanding how these glove injuries are occurring, and to propose mitigations to current designs or design changes in the next generation of EVA gloves.

Overview of crew member energy expenditure during Shuttle Flight 61-8 EASE/ACCESS task performance

NASA Technical Reports Server (NTRS)

Horrigan, D. J.; Waligora, J. W.; Stanford, J.; Edwards, B. F.

1987-01-01

The energy expenditure of the Shuttle Flight 61-B crewmembers during the extravehicular performance of Experimental Assembly of Structures in EVA (EASE) and Assembly Concept of Construction of Space Structures (ACCESS) construction system tasks are reported. These data consist of metabolic rate time profiles correlated with specific EASE and ACCESS tasks and crew comments. Average extravehicular activity metabolic rates are computed and compared with those reported from previous Apollo, Shylab, and Shuttle flights. These data reflect total energy expenditure and not that of individual muscle groups such as hand and forearm. When correlated with specific EVA tasks and subtasks, the metabolic profile data is expected to be useful in planning future EVA protocols. For example, after experiencing high work rates and apparent overheating during some Gemini EVAs, it was found useful to carefully monitor work rates in subsequent flights to assess the adequacy of cooling garments and as an aid to preplanning EVA procedures. This presentation is represented by graphs and charts.

SYBR Green Real-Time PCR for the Detection of All Enterovirus-A71 Genogroups

PubMed Central

Dubot-Pérès, Audrey; Tan, Charlene Y. Q.; de Chesse, Reine; Sibounheuang, Bountoy; Vongsouvath, Manivanh; Phommasone, Koukeo; Bessaud, Maël; Gazin, Céline; Thirion, Laurence; Phetsouvanh, Rattanaphone; Newton, Paul N.; de Lamballerie, Xavier

2014-01-01

Enterovirus A71 (EV-A71) has recently become an important public health threat, especially in South-East Asia, where it has caused massive outbreaks of Hand, Foot and Mouth disease every year, resulting in significant mortality. Rapid detection of EV-A71 early in outbreaks would facilitate implementation of prevention and control measures to limit spread. Real-time RT-PCR is the technique of choice for the rapid diagnosis of EV-A71 infection and several systems have been developed to detect circulating strains. Although eight genogroups have been described globally, none of these PCR techniques detect all eight. We describe, for the first time, a SYBR Green real-time RT-PCR system validated to detect all 8 EV-A71 genogroups. This tool could permit the early detection and shift in genogroup circulation and the standardization of HFMD virological diagnosis, facilitating networking of laboratories working on EV-A71 in different regions. PMID:24651608

Extra dose due to extravehicular activity during the NASA4 mission measured by an on-board TLD system.

PubMed

Deme, S; Apathy, I; Hejja, I; Lang, E; Feher, I

1999-01-01

A microprocessor-controlled on-board TLD system, 'Pille'96', was used during the NASA4 (1997) mission to monitor the cosmic radiation dose inside the Mir Space Station and to measure the extra dose to two astronauts in the course of their extravehicular activity (EVA). For the EVA dose measurements, CaSO4:Dy bulb dosemeters were located in specially designed pockets of the ORLAN spacesuits. During an EVA lasting 6 h, the dose ratio inside and outside Mir was measured. During the EVA, Mir crossed the South Atlantic Anomaly (SAA) three times. Taking into account the influence of these three crossings the mean EVA/internal dose rate ratio was 3.2. Internal dose mapping using CaSO4:Dy dosemeters gave mean dose rates ranging from 9.3 to 18.3 microGy h-1 at locations where the shielding effect was not the same. Evaluation results of the high temperature region of LiF dosemeters are given to estimate the mean LET.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holley, W H

This report describes the results of the literature search, interviews, and site visits conducted during the first six months of this subcontract. This survey was conducted to establish a baseline of information about thermal and photothermal degradation of EVA and case history surveys on discoloration (yellowing/browning) of EVA-based encapsulants in fielded flat-plate PV modules. The literature search revealed that EVA will undergo thermolysis of the acetate groups at temperatures of 130{degrees}C to 150{degrees}C and above, leading to formation of double bonds in the backbone of the copolymer. The survey of case histories of EVA-based encapsulant discoloration in fielded modules inmore » the United States revealed that the problem is limited to those areas of the west and southwest that have comparatively high solar insolation and ambient temperature. It is clear that the discoloration problem is not limited to the modules of any one manufacturer. Discoloration in the EVA encapsulant was experienced in fielded modules from all major US module producers.« less

EVA Skills Training

NASA Technical Reports Server (NTRS)

Parazynski, Scott

2012-01-01

Dr. Parazynski and a colleague from Extravehicular Activity (EVA), Robotics, & Crew Systems Operations (DX) worked closely to build the EVA Skills Training Program, and for the first time, defined the gold standards of EVA performance, allowing crewmembers to increase their performance significantly. As part of the program, individuals had the opportunity to learn at their own rate, taking additional water time as required, to achieve that level of performance. This focus on training to one's strengths and weaknesses to bolster them enabled the Crew Office and DX to field a much larger group of spacewalkers for the daunting "wall of EVA" required for the building and maintenance of the ISS. Parazynski also stressed the need for designers to understand the capabilities and the limitations of a human in a spacesuit, as well as opportunities to improve future generations of space. He shared lessons learned (how the Crew Office engaged in these endeavors) and illustrated the need to work as a team to develop these complex systems.

Design, development and evaluation of Stanford/Ames EVA prehensors

NASA Technical Reports Server (NTRS)

Leifer, Larry J.; Aldrich, J.; Leblanc, M.; Sabelman, E.; Schwandt, D.

1988-01-01

Space Station operations and maintenance are expected to make unprecedented demands on astronaut EVA. With Space Station expected to operate with an 8 to 10 psi atmosphere (4 psi for Shuttle operations), the effectivness of pressurized gloves is called into doubt at the same time that EVA activity levels are to be increased. To address the need for more frequent and complex EVA missions and also to extend the dexterity, duration, and safety of EVA astronauts, NASA Ames and Stanford University have an ongoing cooperative agreement to explore and compare alternatives. This is the final Stanford/Ames report on manually powered Prehensors, each of which consists of a shroud forming a pressure enclosure around the astronaut's hand, and a linkage system to transfer the motions and forces of the hand to mechanical digits attached to the shroud. All prehensors are intended for attachment to a standard wrist coupling, as found on the AX-5 hard suit prototype, so that realistic tests can be performed under normal and reduced gravity as simulated by water flotation.

Improved photostability of NREL-developed EVA pottant formulations for PV module encapsulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Glick, S.H.

1997-12-31

Several new formulations of ethylene vinyl acetate (EVA)-based encapsulant have been developed at NREL and have greatly improved photostability against UV-induced discoloration. The new EVA formulations use stabilizers and a curing agent entirely different from any of those used in existing formulations known to the authors. No discoloration was observed for the laminated and cured samples that were exposed to a {approximately}5-sun UV light (300--400 nm) from a solar simulator at a black panel temperature (BPT) of 44 {+-} 2 C for {approximately}3250 h followed by at 85 C for {approximately}850 h, an equivalent of approximately 9.4 years for anmore » average 6-h daily, 1-sun solar exposure in Golden, Colorado. Under the same conditions, substantial discoloration and premature delamination were observed for two commercial EVA formulations. Encapsulation with the new EVA formulations should extend the long-term stability for PV modules in the field, especially when coupled with UV-filtering, Ce-containing glass superstrates.« less

Apollo 15 time and motion study

NASA Technical Reports Server (NTRS)

Kubis, J. F.; Elrod, J. T.; Rusnak, R.; Barnes, J. E.

1972-01-01

A time and motion study of Apollo 15 lunar surface activity led to examination of four distinct areas of crewmen activity. These areas are: an analysis of lunar mobility, a comparative analysis of tasks performed in 1-g training and lunar EVA, an analysis of the metabolic cost of two activities that are performed in several EVAs, and a fall/near-fall analysis. An analysis of mobility showed that the crewmen used three basic mobility patterns (modified walk, hop, side step) while on the lunar surface. These mobility patterns were utilized as adaptive modes to compensate for the uneven terrain and varied soil conditions that the crewmen encountered. A comparison of the time required to perform tasks at the final 1-g lunar EVA training sessions and the time required to perform the same task on the lunar surface indicates that, in almost all cases, it took significantly more time (on the order of 40%) to perform tasks on the moon. This increased time was observed even after extraneous factors (e.g., hardware difficulties) were factored out.

Advanced Extravehicular Protective Systems (AEPS) study

NASA Technical Reports Server (NTRS)

Williams, J. L.; Copeland, R. J.; Webbon, B. W.

1971-01-01

A description is given of life support subsystem concepts for advanced extravehicular protective systems (AEPS) intended for use on future orbital, lunar surface, and Mars surface missions in the late 1970's and 1980's. Primary interest was centered around the thermal control and carbon dioxide control subsystems because they offer the greatest potential for total weight savings. Emphasis was placed on the generation of regenerable subsystem concepts; however, partially regenerable and expendable concepts were also considered. Previously conceived and developed subsystem concepts were included in the study. Concepts were evaluated on the basis of subsystem weight and volume, and subsystem contribution to parent vehicle weight and volume, which included spares, regeneration equipment, expendables, expandables storage penalty, power penalty, and process heating or cooling penalty. Results are presented showing total weight and volume penalty as a function of total mission extravehicular activity (EVA) hours, and showing EVA weight and volume as a function of EVA duration. Subsystem concepts are recommended for each life support function, and secondary concepts which should be developed are also identified.

Space Flight Decompression Sickness Contingency Plan

NASA Technical Reports Server (NTRS)

Dervay, Joseph; Gernhardt, Michael L.; Ross, Charles E.; Hamilton, Douglas; Homick, Jerry L. (Technical Monitor)

2000-01-01

The purpose was to develop an enhanced plan to diagnose, treat, and manage decompression sickness (DCS) during extravehicular activity (EVA). This plan is merited by the high frequency of upcoming EVAs necessary to construct and maintain the International Space Station (ISS). The upcoming ISS era will demand a significant increase in EVA. The DCS Risk and Contingency Plan provided a new and improved approach to DCS reporting, treatment, management, and training.

STS-64 extravehicular activity (EVA) hardware view

NASA Image and Video Library

1993-01-21

S93-26918 (8 Sept. 1994) --- Scott Bleisath, an extravehicular activity (EVA) engineer, demonstrates the hand control module for the Simplified Aid for EVA Rescue (SAFER) system making its first flight on the scheduled September STS-64 mission. Astronauts Mark C. Lee and Carl J. Meade are the spacewalkers assigned to test the system in space. Unidentified technicians and engineers look on. Photo credit: NASA or National Aeronautics and Space Administration

Understanding Skill in EVA Mass Handling. Volume 4; An Integrated Methodology for Evaluating Space Suit Mobility and Stability

NASA Technical Reports Server (NTRS)

McDonald, P. Vernon; Newman, Dava

1999-01-01

The empirical investigation of extravehicular activity (EVA) mass handling conducted on NASA's Precision Air-Bearing Floor led to a Phase I SBIR from JSC. The purpose of the SBIR was to design an innovative system for evaluating space suit mobility and stability in conditions that simulate EVA on the surface of the Moon or Mars. The approach we used to satisfy the Phase I objectives was based on a structured methodology for the development of human-systems technology. Accordingly the project was broken down into a number of tasks and subtasks. In sequence, the major tasks were: 1) Identify missions and tasks that will involve EVA and resulting mobility requirements in the near and long term; 2) Assess possible methods for evaluating mobility of space suits during field-based EVA tests; 3) Identify requirements for behavioral evaluation by interacting with NASA stakeholders;.4) Identify necessary and sufficient technology for implementation of a mobility evaluation system; and 5) Prioritize and select technology solutions. The work conducted in these tasks is described in this final volume of the series on EVA mass handling. While prior volumes in the series focus on novel data-analytic techniques, this volume addresses technology that is necessary for minimally intrusive data collection and near-real-time data analysis and display.

Miniature EVA Software Defined Radio

NASA Technical Reports Server (NTRS)

Pozhidaev, Aleksey

2012-01-01

As NASA embarks upon developing the Next-Generation Extra Vehicular Activity (EVA) Radio for deep space exploration, the demands on EVA battery life will substantially increase. The number of modes and frequency bands required will continue to grow in order to enable efficient and complex multi-mode operations including communications, navigation, and tracking applications. Whether conducting astronaut excursions, communicating to soldiers, or first responders responding to emergency hazards, NASA has developed an innovative, affordable, miniaturized, power-efficient software defined radio that offers unprecedented power-efficient flexibility. This lightweight, programmable, S-band, multi-service, frequency- agile EVA software defined radio (SDR) supports data, telemetry, voice, and both standard and high-definition video. Features include a modular design, an easily scalable architecture, and the EVA SDR allows for both stationary and mobile battery powered handheld operations. Currently, the radio is equipped with an S-band RF section. However, its scalable architecture can accommodate multiple RF sections simultaneously to cover multiple frequency bands. The EVA SDR also supports multiple network protocols. It currently implements a Hybrid Mesh Network based on the 802.11s open standard protocol. The radio targets RF channel data rates up to 20 Mbps and can be equipped with a real-time operating system (RTOS) that can be switched off for power-aware applications. The EVA SDR's modular design permits implementation of the same hardware at all Network Nodes concept. This approach assures the portability of the same software into any radio in the system. It also brings several benefits to the entire system including reducing system maintenance, system complexity, and development cost.

Simulation of Martian EVA at the Mars Society Arctic Research Station

NASA Astrophysics Data System (ADS)

Pletser, V.; Zubrin, R.; Quinn, K.

The Mars Society has established a Mars Arctic Research Station (M.A.R.S.) on Devon Island, North of Canada, in the middle of the Haughton crater formed by the impact of a large meteorite several million years ago. The site was selected for its similarities with the surface of the Mars planet. During the Summer 2001, the MARS Flashline Research Station supported an extended international simulation campaign of human Mars exploration operations. Six rotations of six person crews spent up to ten days each at the MARS Flashline Research Station. International crews, of mixed gender and professional qualifications, conducted various tasks as a Martian crew would do and performed scientific experiments in several fields (Geophysics, Biology, Psychology). One of the goals of this simulation campaign was to assess the operational and technical feasibility of sustaining a crew in an autonomous habitat, conducting a field scientific research program. Operations were conducted as they would be during a Martian mission, including Extra-Vehicular Activities (EVA) with specially designed unpressurized suits. The second rotation crew conducted seven simulated EVAs for a total of 17 hours, including motorized EVAs with All Terrain Vehicles, to perform field scientific experiments in Biology and Geophysics. Some EVAs were highly successful. For some others, several problems were encountered related to hardware technical failures and to bad weather conditions. The paper will present the experiment programme conducted at the Mars Flashline Research Station, the problems encountered and the lessons learned from an EVA operational point of view. Suggestions to improve foreseen Martian EVA operations will be discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Czanderna, A.W.

Yellow-browning of the ethylene-vinyl acetate (EVA) copolymer encapsulant used in PV modules has resulted in significant power losses of over 50% of the initial power output. The weathering-degraded yellow-brown EVA films have lost the ultraviolet (UV) absorber, Cyasorb UV 531[sup (R)], and the degree of cross-linking (gel content) has increased. EVA degradation mechanisms identified thus far are discussed in this work. Upon exposure to UV light at 45[degree]--85 [degree]C, virgin EVA films that are stabilized with Cyasorb UV 531[sup (R)] and two antioxidants show an increase in the gel content, a gradual loss of Cyasorb by photooxidation, and the generationmore » of acetic acid. The deacetylation reaction, which leads to the formation of polyenes, also occurs significantly in the films heated in the dark at 130 [degree]C for five days. Acetic acid thermally catalyzes the EVA film discoloration at 85[degree]--130 [degree]C, which increases from a light yellow to a yellow-brown color as the heating temperature increases. The factors can account for the yellow-browning of the EVA in the accelerated testing of mini-modules, and the discoloration is more profound when exposed to UV light at 85 [degree]C than when heated in the dark at the same temperature. In the presence of the EVA-produced acetic acid, oxygen, and sunlight exposure, the Cu buslines that were coated with a thin layer of Pb-Sn alloy showed significant oxidation and metal interdiffusion, which in turn may contribute to the resistance increase and hence the current loss reported for weathered PV modules.« less

Shape Analysis and Deployment of the ExaVolt Antenna

NASA Astrophysics Data System (ADS)

Baginski, Frank; Zhao, Kaiyu; Furer, Joshua; Landay, Justin; Bailoor, Shantanu; Gorham, Peter; Varner, Gary; Miki, Christian; Hill, Brian; Schoorlemmer, Harm; Nguyen, Liem; Romero-Wolf, Andrew; Liewer, Kurt; Sauder, Jonathan; Brakke, Kenneth; Beatty, Jim; Connolly, Amy; Allison, Patrick; Pfendner, Carl; Dailey, Brian; Fairbrother, Debra; Said, Magdi; Lang, Steven; Young, Leyland

The ExaVolt Antenna (EVA) is the next generation balloon-borne ultra-high energy (UHE) particle observatory under development for NASA’s suborbital super-pressure balloon program in Antarctica. Unlike a typical mission where the balloon lifts a gondola that carries the primary scientific instrument, the EVA mission is a first-of-its-kind in that the balloon itself is part of the science instrument. Specifically, a toroidal RF reflector is mounted onto the outside surface of a superpressure balloon (SPB) and a feed antenna is suspended inside the balloon, creating a high-gain antenna system with a synoptic view of the Antarctic ice sheet. The EVA mission presents a number of technical challenges. For example, can a stowed feed antenna be inserted through an opening in the top-plate? Can the feed antenna be deployed during the ascent? Once float altitude is achieved, how might small shape changes in the balloon shape affect the antenna performance over the life of the EVA mission? The EVA team utilized a combination of testing with a 1/20-scale physical model, mathematical modeling and numerical simulations to probe these and related questions. While the problems are challenging, they are solvable with current technology and expertise. Experiments with a 1/20-scale EVA physical model outline a pathway for inserting a stowed feed into a SPB. Analysis indicates the EVA system will ascend, deploy and assume a stable configuration at float altitude. Nominal shape changes in an Antarctic SPB are sufficiently small to allow the use of the surface of the balloon as a high-gain reflector.

Fifteen-minute Extravehicular Activity Prebreathe Protocol Using NASA's Exploration Atmosphere (8.2 psia/ 34% 02)

NASA Technical Reports Server (NTRS)

Abercromby, Andrew F. J.; Gernhardt, Michael L.; Conkin, Johnny

2013-01-01

A TBDM DCS probability model based on an existing biophysical model of inert gas bubble growth provides significant prediction and goodness-of-fit with 84 cases of DCS in 668 human altitude exposures. 2. Model predictions suggest that 15-minute O2 prebreathe protocols used in conjunction with suit ports and an 8.2 psi, 34% O2, 66% N2 atmosphere may enable rapid EVA capability for future exploration missions with the risk of DCS = 12%. ? EVA could begin immediately at 6.0 psi, with crewmembers decreasing suit pressure to 4.3 psi after completing the 15-minute in-suit prebreathe. 3. Model predictions suggest that intermittent recompression during exploration EVA may reduce decompression stress by 1.8% to 2.3% for 6 hours of total EVA time. Savings in gas consumables and crew time may be accumulated by abbreviating the EVA suit N2 purge to 2 minutes (20% N2) compared with 8 minutes (5% N2) at the expense of an increase in estimated decompression risk of up to 2.4% for an 8-hour EVA. ? Increased DCS risk could be offset by IR or by spending additional time at 6 psi at the beginning of the EVA. ? Savings of 0.48 lb of gas and 6 minutes per person per EVA corresponds to more than 31 hours of crew time and 1800 lb of gas and tankage under the Constellation lunar architecture. 6. Further research is needed to characterize and optimize breathing mixtures and intermittent recompression across the range of environments and operational conditions in which astronauts will live and work during future exploration missions. 7. Development of exploration prebreathe protocols will begin with definition of acceptable risk, followed by development of protocols based on models such as ours, and, ultimately, validation of protocols through ground trials before operational implementation.

The Epidemiology of Hand, Foot and Mouth Disease in Asia: A Systematic Review and Analysis.

PubMed

Koh, Wee Ming; Bogich, Tiffany; Siegel, Karen; Jin, Jing; Chong, Elizabeth Y; Tan, Chong Yew; Chen, Mark Ic; Horby, Peter; Cook, Alex R

2016-10-01

Hand, foot and mouth disease (HFMD) is a widespread pediatric disease caused primarily by human enterovirus 71 (EV-A71) and Coxsackievirus A16 (CV-A16). This study reports a systematic review of the epidemiology of HFMD in Asia. PubMed, Web of Science and Google Scholar were searched up to December 2014. Two reviewers independently assessed studies for epidemiologic and serologic information about prevalence and incidence of HFMD against predetermined inclusion/exclusion criteria. Two reviewers extracted answers for 8 specific research questions on HFMD epidemiology. The results are checked by 3 others. HFMD is found to be seasonal in temperate Asia with a summer peak and in subtropical Asia with spring and fall peaks, but not in tropical Asia; evidence of a climatic role was identified for temperate Japan. Risk factors for HFMD include hygiene, age, gender and social contacts, but most studies were underpowered to adjust rigorously for confounding variables. Both community-level and school-level transmission have been implicated, but their relative importance for HFMD is inconclusive. Epidemiologic indices are poorly understood: No supporting quantitative evidence was found for the incubation period of EV-A71; the symptomatic rate of EV-A71/Coxsackievirus A16 infection was from 10% to 71% in 4 studies; while the basic reproduction number was between 1.1 and 5.5 in 3 studies. The uncertainty in these estimates inhibits their use for further analysis. Diversity of study designs complicates attempts to identify features of HFMD epidemiology. Knowledge on HFMD remains insufficient to guide interventions such as the incorporation of an EV-A71 vaccine in pediatric vaccination schedules. Research is urgently needed to fill these gaps.

Biomedical Support of U.S. Extravehicular Activity

NASA Technical Reports Server (NTRS)

Gernhardt, Michael L.; Dervay, J. P.; Gillis, D.; McMann, H. J.; Thomas, K. S.

2007-01-01

The world's first extravehicular activity (EVA) was performed by A. A. Leonov on March 18, 1965 during the Russian Voskhod-2 mission. The first US EVA was executed by Gemini IV astronaut Ed White on June 3, 1965, with an umbilical tether that included communications and an oxygen supply. A hand-held maneuvering unit (HHMU) also was used to test maneuverability during the brief EVA; however the somewhat stiff umbilical limited controlled movement. That constraint, plus difficulty returning through the vehicle hatch, highlighted the need for increased thermal control and improved EVA ergonomics. Clearly, requirements for a useful EVA were interrelated with the vehicle design. The early Gemini EVAs generated requirements for suits providing micro-meteor protection, adequate visual field and eye protection from solar visual and infrared radiation, gloves optimized for dexterity while pressurized, and thermal systems capable of protecting the astronaut while rejecting metabolic heat during high workloads. Subsequent Gemini EVAs built upon this early experience and included development of a portable environmental control and life support systems (ECLSS) and an astronaut maneuvering unit. The ECLSS provided a pressure vessel and controller with functional control over suit pressure, oxygen flow, carbon dioxide removal, humidity, and temperature control. Gemini EVA experience also identified the usefulness of underwater neutral buoyancy and altitude chamber task training, and the importance of developing reliable task timelines. Improved thermal management and carbon dioxide control also were required for high workload tasks. With the Apollo project, EVA activity was primarily on the lunar surface; and suit durability, integrated liquid cooling garments, and low suit operating pressures (3.75 pounds per square inch absolute [psia] or 25.8 kilopascal [kPa],) were required to facilitate longer EVAs with ambulation and significant physical workloads with average metabolic rates of 1000 BTU/hr and peaks of up to 2200 BTU/hr. Mobility was further augmented with the Lunar Roving Vehicle. The Apollo extravehicular mobility unit (EMU) was made up of over 15 components, ranging from a biomedical belt for capturing and transmitting biomedical data, urine and fecal containment systems, a liquid cooling garment, communications cap, a modular portable life support system (PLSS), a boot system, thermal overgloves, and a bubble helmet with eye protection. Apollo lunar astronauts performed successful EVAs on the lunar surface from a 5 psia (34.4 kPa) 100% oxygen environment in the Lunar Lander. A maximum of three EVAs were performed on any mission. For Skylab a modified A7LB suit, used for Apollo 15, was selected. The Skylab astronaut life support assembly (ALSA) provided umbilical support through the life support umbilical (LSU) and used open loop oxygen flow, rather than closed-loop as in Apollo missions. Thermal control was provided by liquid water circulated by spacecraft pumps and electrical power also was provided from the spacecraft via the umbilical. The cabin atmosphere of 5 psia (34.4 kPa), 70% oxygen, provided a normoxic atmosphere and because of the very low nitrogen partial pressures, no special protocols were required to protect against decompression sickness (DCS) as was the case with the Apollo spacecraft with a 5 psi, 100% oxygen environment.

Viscometric investigation of compatibilization of the poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) blends by terpolymer of maleic anhydride styrene vinyl acetate

NASA Astrophysics Data System (ADS)

İmren, Dilek; Boztuğ, Ali; Yılmaz, Ersen; Zengin, H. Bayram

2008-11-01

In this study, a blend of poly(vinyl chloride) (PVC)/ethylene-co-vinyl acetate (EVA) was compatibilized by terpolymer of maleic anhydride-styrene-vinyl acetate (MAStVA) used as a compatibilizer. It was prepared the blends of 50/50 PVC/EVA containing 2-10% of the terpolymer. The compatibility experiences of these blends were investigated by using viscometric method in the range of concentrations (0.5-2.0 g dL -1) where tetrahydrofuran (THF) is the solvent. The interaction parameter (Δ b) was used to study the miscibility and compatibility of polymer blend in solution, obtained from the modified Krigbaum and Wall theory. Turbidity and FTIR measurements were also used to investigate the miscibility of this pair of polymers. The values of the relative viscosities of the each polymer solution and their blends were measured by a Cannon-Fenske type viscometer. In consequence of the study, it was observed that a considerable improvement was achieved in the miscibility of PVC/EVA blends by adding among 5 and 10 wt% of compatibilizer.

An Onboard ISS Virtual Reality Trainer

NASA Technical Reports Server (NTRS)

Miralles, Evelyn

2013-01-01

Prior to the retirement of the Space Shuttle, many exterior repairs on the International Space Station (ISS) were carried out by shuttle astronauts, trained on the ground and flown to the Station to perform these specific repairs. With the retirement of the shuttle, this is no longer an available option. As such, the need for ISS crew members to review scenarios while on flight, either for tasks they already trained for on the ground or for contingency operations has become a very critical issue. NASA astronauts prepare for Extra-Vehicular Activities (EVA) or Spacewalks through numerous training media, such as: self-study, part task training, underwater training in the Neutral Buoyancy Laboratory (NBL), hands-on hardware reviews and training at the Virtual Reality Laboratory (VRLab). In many situations, the time between the last session of a training and an EVA task might be 6 to 8 months. EVA tasks are critical for a mission and as time passes the crew members may lose proficiency on previously trained tasks and their options to refresh or learn a new skill while on flight are limited to reading training materials and watching videos. In addition, there is an increased need for unplanned contingency repairs to fix problems arising as the Station ages. In order to help the ISS crew members maintain EVA proficiency or train for contingency repairs during their mission, the Johnson Space Center's VRLab designed an immersive ISS Virtual Reality Trainer (VRT). The VRT incorporates a unique optical system that makes use of the already successful Dynamic On-board Ubiquitous Graphics (DOUG) software to assist crew members with procedure reviews and contingency EVAs while on board the Station. The need to train and re-train crew members for EVAs and contingency scenarios is crucial and extremely demanding. ISS crew members are now asked to perform EVA tasks for which they have not been trained and potentially have never seen before. The Virtual Reality Trainer (VRT) provides an immersive 3D environment similar to the one experienced at the VRLab crew training facility at the NASA Johnson Space Center. VRT bridges the gap by allowing crew members to experience an interactive, 3D environment to reinforce skills already learned and to explore new work sites and repair procedures outside the Station.

Time series analysis of reported cases of hand, foot, and mouth disease from 2010 to 2013 in Wuhan, China.

PubMed

Chen, Banghua; Sumi, Ayako; Toyoda, Shin'ichi; Hu, Quan; Zhou, Dunjin; Mise, Keiji; Zhao, Junchan; Kobayashi, Nobumichi

2015-11-03

Hand, foot, and mouth disease (HFMD) is an infectious disease caused by a group of enteroviruses, including Coxsackievirus A16 (CVA16) and Enterovirus A71 (EV-A71). In recent decades, Asian countries have experienced frequent and widespread HFMD outbreaks, with deaths predominantly among children. In several Asian countries, epidemics usually peak in the late spring/early summer, with a second small peak in late autumn/early winter. We investigated the possible underlying association between the seasonality of HFMD epidemics and meteorological variables, which could improve our ability to predict HFMD epidemics. We used a time series analysis composed of a spectral analysis based on the maximum entropy method (MEM) in the frequency domain and the nonlinear least squares method in the time domain. The time series analysis was applied to three kinds of monthly time series data collected in Wuhan, China, where high-quality surveillance data for HFMD have been collected: (i) reported cases of HFMD, (ii) reported cases of EV-A71 and CVA16 detected in HFMD patients, and (iii) meteorological variables. In the power spectral densities for HFMD and EV-A71, the dominant spectral lines were observed at frequency positions corresponding to 1-year and 6-month cycles. The optimum least squares fitting (LSF) curves calculated for the 1-year and 6-month cycles reproduced the bimodal cycles that were clearly observed in the HFMD and EV-A71 data. The peak months on the LSF curves for the HFMD data were consistent with those for the EV-A71 data. The risk of infection was relatively high at 10 °C ≤ t < 15 °C (t, temperature [°C]) and 15 °C ≤ t < 20 °C, and peaked at 20 °C ≤ t < 25 °C. In this study, the HFMD infections occurring in Wuhan showed two seasonal peaks, in summer (June) and winter (November or December). The results obtained with a time series analysis suggest that the bimodal seasonal peaks in HFMD epidemics are attributable to EV-A71 epidemics. Our results suggest that controlling the spread of EV-A71 infections when the temperature is approximately 20-25 °C should be considered to prevent HFMD infections in Wuhan, China.

Russian EVA 36.

NASA Image and Video Library

2013-11-09

ISS037-E-028082 (9 Nov. 2013) --- Russian cosmonaut Sergey Ryazanskiy, Expedition 37 flight engineer, attired in a Russian Orlan spacesuit, participates in a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Ryazanskiy and Russian cosmonaut Oleg Kotov (out of frame) continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22.

Russian EVA 36.

NASA Image and Video Library

2013-11-09

ISS037-E-028067 (9 Nov. 2013) --- Russian cosmonaut Oleg Kotov, Expedition 37 flight engineer, attired in a Russian Orlan spacesuit, participates in a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Kotov and Russian cosmonaut Sergey Ryazanskiy (out of frame) continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22.

Russian EVA 36.

NASA Image and Video Library

2013-11-09

ISS037-E-028101 (9 Nov. 2013) --- Russian cosmonaut Oleg Kotov, Expedition 37 flight engineer, attired in a Russian Orlan spacesuit, participates in a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Kotov and Russian cosmonaut Sergey Ryazanskiy (out of frame) continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22.

Russian EVA 36.

NASA Image and Video Library

2013-11-09

ISS037-E-028094 (9 Nov. 2013) --- Russian cosmonaut Oleg Kotov, Expedition 37 flight engineer, attired in a Russian Orlan spacesuit, participates in a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Kotov and Russian cosmonaut Sergey Ryazanskiy (out of frame) continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22.

Russian EVA 36.

NASA Image and Video Library

2013-11-09

ISS037-E-028107 (9 Nov. 2013) --- Russian cosmonaut Oleg Kotov, Expedition 37 flight engineer, attired in a Russian Orlan spacesuit, participates in a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Kotov and Russian cosmonaut Sergey Ryazanskiy (out of frame) continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22.

Russian EVA 36.

NASA Image and Video Library

2013-11-09

ISS037-E-028102 (9 Nov. 2013) --- Russian cosmonaut Oleg Kotov, Expedition 37 flight engineer, attired in a Russian Orlan spacesuit, participates in a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Kotov and Russian cosmonaut Sergey Ryazanskiy (out of frame) continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22.

Assessment of Scheduling and Plan Execution of Apollo 14 Lunar Surface Operations

NASA Technical Reports Server (NTRS)

Marquez, Jessica J.

2010-01-01

Although over forty years have passed since first landing on the Moon, there is not yet a comprehensive, quantitative assessment of Apollo extravehicular activities (EVAs). Quantitatively evaluating lunar EVAs will provide a better understanding of the challenges involved with surface operations. This first evaluation of a surface EVA centers on comparing the planned and the as-ran timeline, specifically collecting data on discrepancies between durations that were estimated versus executed. Differences were summarized by task categories in order to gain insight as to the type of surface operation activities that were most challenging. One Apollo 14 EVA was assessed utilizing the described methodology. Selected metrics and task categorizations were effective, and limitations to this process were identified.

Concepts for the evolution of the Space Station Program

NASA Technical Reports Server (NTRS)

Michaud, Roger B.; Miller, Ladonna J.; Primeaux, Gary R.

1986-01-01

An evaluation is made of innovative but pragmatic waste management, interior and exterior orbital module construction, Space Shuttle docking, orbital repair operation, and EVA techniques applicable to the NASA Space Station program over the course of its evolution. Accounts are given of the Space Shuttle's middeck extender module, an on-orbit module assembly technique employing 'Pringles' stack-transportable conformal panels, a flexible Shuttle/Space Station docking tunnel, an 'expandable dome' for transfer of objects into the Space Station, and a Space Station dual-hatch system. For EVA operations, pressurized bubbles with articulating manipulator arms and EVA hard suits incorporating maneuvering, life support and propulsion capabilities, as well as an EVA gas propulsion system, are proposed. A Space Station ultrasound cleaning system is also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holley, W A

This report describes work performed under a subcontract to the National Renewable Energy Laboratory under the Photovoltaic Manufacturing Technology Project. The objectives of this subcontract are to (1) define the problem of yellowing/browning of EVA-based encapsulants; (2) determine probable mechanisms and the role of various parameters such as heat, UV exposure, module construction, EVA interfaces, and EVA thickness, in the browning of EVA-based encapsulants; (3) develop stabilization strategies for various module constructions to protect the encapsulant from degradative failure; (4) conduct laboratory, accelerated outdoor, and field testing of encapsulant, laminated test coupons, and full modules to demonstrate the functional adequacymore » of the stabilization strategies; and (5) implement these strategies. This report summarizes the accomplishments related to the above goals for the reporting period.« less

Novel antibacterial mouthguard material manufactured using silver-nanoparticleembedded ethylene-vinyl acetate copolymer masterbatch.

PubMed

Yoshida, Yuriko; Churei, Hiroshi; Takeuchi, Yasuo; Wada, Takahiro; Uo, Motohiro; Izumi, Yuichi; Ueno, Toshiaki

2018-01-26

The purpose of the present study was to develop an antibacterial mouthguard (MG) material using a masterbatch of silvernanoparticle-embedded ethylene-vinyl acetate (EVA) copolymers. In order to verify that the testing material was clinically applicable as an antibacterial MG material, we conducted an antibacterial test, a shock absorption test, and analysis of in vitro silver release. The colony-forming activity of Streptococcus sobrinus, Porphyromonas gingivalis, and Escherichia coli were significantly inhibited on the testing materials compared with the commercial EVA sheet (p<0.05). The shock absorption capability of the testing material was not significantly different from that of the commercial EVA sheet. Cumulative silver release (in pure water) from the testing materials were infinitesimal after soaking for 20 days, which implied that there could be no harm in wearing the MG during exercise. These results showed that this testing material could be clinically applicable as an antibacterial MG material.

EVA Radio DRATS 2011 Report

NASA Technical Reports Server (NTRS)

Swank, Aaron J.; Bakula, Casey J.

2012-01-01

In the Fall of 2011, National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) participated in the Desert Research and Technology Studies (DRATS) field experiments held near Flagstaff, Arizona. The objective of the DRATS outing is to provide analog mission testing of candidate technologies for space exploration, especially those technologies applicable to human exploration of extra- terrestrial rocky bodies. These activities are performed at locations with similarities to extra-terrestrial conditions. This report describes the Extravehicular Activity (EVA) Dual-Band Radio Communication System which was demonstrated during the 2011 outing. The EVA radio system is designed to transport both voice and telemetry data through a mobile ad hoc wireless network and employs a dual-band radio configuration. Some key characteristics of this system include: 1. Dual-band radio configuration. 2. Intelligent switching between two different capability wireless networks. 3. Self-healing network. 4. Simultaneous data and voice communication.

Mechanisms of Injury and Countermeasures for EVA Associated Upper Extremity Medical Issues: Extended Vent Tube Study

NASA Technical Reports Server (NTRS)

Jones, Jeff; Hoffman, Ron; Harvey, Craig; Bowen, C. K.; Hudy, C. E.; Tuxhorn, Jennifer; Gernhardt, Mike; Scheuring, Richard A.

2007-01-01

The goal of this study is to determine the role that moisture plays in the injury to the fingers and fingernails during EVA training operations in the Neutral Buoyancy Laboratory. Current Extravehicular Mobility Unit (EMU, with a PLSS) as configured in the NBL was used for all testing and a vent tube was extended down a single arm of the crewmember during the test; vent tube was moved between left and right arm to serve as experimental condition being investigated and the other arm served as control condition.

[Heat transfer analysis of liquid cooling garment used for extravehicular activity].

PubMed

Qiu, Y F; Yuan, X G; Mei, Z G; Jia, S G; Ouyang, H; Ren, Z S

2001-10-01

Brief description was given about the construction and function of the LCG (liquid cooling garment) used for EVA (extravehicular activity). The heat convection was analyzed between ventilating gas and LCG, the heat and mass transfer process was analyzed too, then a heat and mass transfer mathematical model of LCG was developed. Thermal physiological experimental study with human body wearing LVCG (liquid cooling and ventilation garment) used for EVA was carried out to verify this mathematical model. This study provided a basis for the design of liquid-cooling and ventilation system for the space suit.

EVA 3

NASA Image and Video Library

2005-08-03

S114-E-6893 (3 August 2005) --- Astronaut Soichi Noguchi, STS-114 mission specialist representing Japan Aerospace Exploration Agency (JAXA), participates in the mission’;s third session of extravehicular activity (EVA).

EVA 3

NASA Image and Video Library

2005-08-03

S114-E-6897 (3 August 2005) --- Astronaut Soichi Noguchi, STS-114 mission specialist representing Japan Aerospace Exploration Agency (JAXA), participates in the mission’;s third session of extravehicular activity (EVA).

Artemyev post-EVA

NASA Image and Video Library

2014-06-19

Cosmonaut Oleg Artemyev, Expedition 40 flight engineer, is photographed still wearing his liquid cooling and ventilation garment after a Russian Extravehicular Activity (EVA). Artemyev is standing in his crew quarters (CQ).

The Utility of a Small Pressurized Rover with Suit Ports for Lunar Exploration: A Geologist's Perspective

NASA Technical Reports Server (NTRS)

Kring, David A.; Bleacher, Jacob E.; Garry, W. Brent; Love, Stanley G.; Young, Kelsey E.

2017-01-01

Rover trade study: As summarized recently, mission simulations at Black Point Lava Flow (Arizona) that included realistic extravehicular activity (EVA) tasking, accurate traverse timelines, and an in-loop science CAPCOM (or SciCOM) showed that a small pressurized rover (SPR) was a better mobility asset than an unpressurized rover (UPR). Traverses within the SPR were easier on crew than spending an entire day in a spacesuit, enhancing crew productivity at each station. The SPR, named Lunar Electric Rover (LER), and sometimes called the Space Exploration Vehicle (SEV), could also provide shelter during a suit malfunction, radiation event, or medical emergency that might occur on the Moon. Intravehicular activity (IVA) capabilities: From within the vehicle, crew could describe and photo-document distant features during drives between stations, as well as in the near-field, directly in front of the LER, providing an ability to begin EVA planning on approach to each outcrop prior to egress. The vehicle can rotate 360º without any lateral movement, providing views in all directions. It has high-visibility windows, a ForeCam, AftCam, port and starboard cameras, docking cameras, and a GigaPan camera. EVA capabilities: To reduce timeline, mass, and volumetric overhead, rapid egress and ingress were envisioned, replacing an airlock with lower cabin pressure than on the International Space Station and suit ports on the aft cabin wall [2]. When needed for closer inspection and sample collecting, crew could egress in about 10 minutes through suit ports. Crew use SuitCams for additional photo-documentation, transmit mobile observations verbally, and collect surface materials. Typical simulations involved 3 to 4 EVA stations/day and 2 to 3 hr/day of boots on the ground. This allowed crew to explore a far larger territory, with more complex geological and in situ resource utilization (ISRU) features, than would a single, longer-duration EVA at one location, while also minimizing crew time in a spacesuit. Additionally, the vehicle could be driven with crew locked into the suit ports. This approach could involve a driver in the cockpit with a suited crewmember in a suit port, or the vehicle could be driven from the aft deck with both crewmembers in their suit ports. This approach was used when distances between stops were short enough that vehicle ingress and egress were less efficient than remaining in the suits and driving. Utility of suit ports: The advantages of suit ports were clearly demonstrated in those field-based trade studies. To illustrate those advantages further, consider the consequences of a SPR without suit ports at the Apollo 17 landing site. At that site, the crew's second EVA was an approximately 18 km loop conducted in a UPR, called the Lunar Roving Vehicle (LRV), in 7 hr 36 min 56 s. The traverse was composed of 5 formal stations, plus 8 additional LRV stations where crew made brief scientific stops. In a scenario involving a SPR without suit ports, crew would go EVA through an airlock and probably be limited to a single EVA per day. In that case, crew could drive the SPR 9 km from the landing site to station 2, go EVA, and complete station 2 tasks. However, to conduct station 3 tasks, the crew would then need to walk approximately 3 km to station 3, while ground control in Houston tele-robotically drives the LER to station 3. A walk of approximately 3 km is possible, as that is what the Apollo 14 crew did before LRVs were deployed, but it is a lengthy and potentially grueling EVA. Assuming crew completes station 3 tasks, they would likely need to re-enter the SPR, ending the day's EVA, and return to the landing site. They would not be able to walk the additional distances to stations 4 and 5 (the latter being about 6 km from station 3). Thus, crew in an SPR without suit ports would require two days to accomplish the same tasks Apollo 17 crew completed in a single day. If a future crew is involved in long duration traverses on the lunar surface, the deployment of a vehicle with suit ports would probably be a better solution.

Creating a Lunar EVA Work Envelope

NASA Technical Reports Server (NTRS)

Griffin, Brand N.; Howard, Robert; Rajulu, Sudhakar; Smitherman, David

2009-01-01

A work envelope has been defined for weightless Extravehicular Activity (EVA) based on the Space Shuttle Extravehicular Mobility Unit (EMU), but there is no equivalent for planetary operations. The weightless work envelope is essential for planning all EVA tasks because it determines the location of removable parts, making sure they are within reach and visibility of the suited crew member. In addition, using the envelope positions the structural hard points for foot restraints that allow placing both hands on the job and provides a load path for reacting forces. EVA operations are always constrained by time. Tasks are carefully planned to ensure the crew has enough breathing oxygen, cooling water, and battery power. Planning first involves computers using a virtual work envelope to model tasks, next suited crew members in a simulated environment refine the tasks. For weightless operations, this process is well developed, but planetary EVA is different and no work envelope has been defined. The primary difference between weightless and planetary work envelopes is gravity. It influences anthropometry, horizontal and vertical mobility, and reaction load paths and introduces effort into doing "overhead" work. Additionally, the use of spacesuits other than the EMU, and their impacts on range of motion, must be taken into account. This paper presents the analysis leading to a concept for a planetary EVA work envelope with emphasis on lunar operations. There is some urgency in creating this concept because NASA has begun building and testing development hardware for the lunar surface, including rovers, habitats and cargo off-loading equipment. Just as with microgravity operations, a lunar EVA work envelope is needed to guide designers in the formative stages of the program with the objective of avoiding difficult and costly rework.

Development of single-step multiplex real-time RT-PCR assays for rapid diagnosis of enterovirus 71, coxsackievirus A6, and A16 in patients with hand, foot, and mouth disease.

PubMed

Puenpa, Jiratchaya; Suwannakarn, Kamol; Chansaenroj, Jira; Vongpunsawad, Sompong; Poovorawan, Yong

2017-10-01

Real-time reverse-transcription polymerase chain reaction (rRT-PCR) to detect enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) has facilitated the rapid and accurate identification of the two most common etiological agents underlying hand, foot, and mouth disease (HFMD). However, the worldwide emergence of CV-A6 infection in HFMD necessitates development of an improved multiplex rRT-PCR method. To rapidly determine the etiology of HFMD, two rRT-PCR assays using TaqMan probes were developed to differentiate among three selected common enteroviruses (EV-A71, CV-A16 and CV-A6) and to enable broad detection of enteroviruses (pan-enterovirus assay). No cross-reactions were observed with other RNA viruses examined. The detection limits of both assays were 10 copies per microliter for EV-A71, CV-A6 and CV-A16, and pan-enterovirus. The methods showed high accuracy (EV-A71, 90.6%; CV-A6, 92.0%; CV-A16, 100%), sensitivity (EV-A71, 96.5%; CV-A6, 95.8%; CV-A16, 99.0%), and specificity (EV-A71, 100%; CV-A6, 99.9%; CV-A16, 99.9%) in testing clinical specimens (n=1049) during 2014-2016, superior to those of conventional RT-PCR. Overall, the multiplex rRT-PCR assays enabled highly sensitive detection and rapid simultaneous typing of EV-A71, CV-A6 and CV-A16, and enteroviruses, rendering them feasible and attractive methods for large-scale surveillance of enteroviruses associated with HFMD outbreaks. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of the Radiation Shielding Properties of US andRussian EVA Suits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benton, E.R.; Benton, E.V.; Frank, A.L.

2001-10-26

Reported herein are results from the Eril Research, Inc.(ERI) participationin the NASA Johnson Space Center sponsored studycharacterizing the radiation shielding properties of the two types ofspace suit that astronauts are wearing during the EVA on-orbit assemblyof the International Space Station (ISS). Measurements using passivedetectors were carried out to assess the shielding properties of the USEMU Suit and the Russian Orlan-M suit during irradiations of the suitsand a tissue equivalent phantom to monoenergetic proton and electronbeams at the Loma Linda University Medical Center (LLUMC). Duringirradiations of 6 MeV electrons and 60 MeV protons, absorbed dose as afunction of depth was measuredmore » using TLDs exposed behind swatches of thetwo suit materials and inside the two EVA helmets. Considerable reductionin electron dosewas measured behind all suit materials in exposures to 6MeV electrons. Slowing of the proton beam in the suit materials led to anincrease in dose measured in exposures to 60 MeV protons. During 232 MeVproton irradiations, measurements were made with TLDs and CR-39 PNTDs atfive organ locations inside a tissue equivalent phantom, exposed bothwith and without the two EVA suits. The EVA helmets produce a 13 to 27percent reduction in total dose and a 0 to 25 percent reduction in doseequivalent when compared to measurements made in the phantom head alone.Differences in dose and dose equivalent between the suit and non-suitirradiations forthe lower portions of the two EVA suits tended to besmaller. Proton-induced target fragmentation was found to be asignificant source of increased dose equivalent, especially within thetwo EVA helmets, and average quality factor inside the EMU and Orlan-Mhelmets was 2 to 14 percent greater than that measured in the barephantom head.« less

Low Cost, Single Layer Replacement for the Back-Sheet and Encapsulant Layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kempe, M. D.; Thapa, P.

2008-01-01

Ethylene propylene diene monomer (EPDM) based polymers have been formulated for specific use in photovoltaic modules to produce better performance and longer term stability at a lower cost than standard materials. EPDM formulations are advantageous over ethylene vinyl-acetate (EVA) because they can use the same lamination/cure cycle as EVA, they do not need a second back-sheet protective material (e.g. PET/Tedlar), they have a lower glass transition temperature, no melting transition, more constant mechanical moduli as a function of temperature, they are less polar than EVA (provides better corrosion protection), and they have excellent damp heat (85 C/85% relative humidity) resistancemore » against delamination. Module designs typically use EVA on the back side of cells despite the fact that transparency is not advantageous. We have developed a single encapsulant layer that will replace standard module back-sheet constructions consisting of EVA/PET/Tedlar. Because a single low-cost material layer is used, it will provide a significant materials cost savings of about $6 to $8/m{sup 2} as compared to traditional back-sheets. Electrical insulation tests were conducted using 0.85 mm thick stainless steel sheets as a model for a cell. It was found that a polymer layer thickness of about 0.33mm provided better high voltage electrical insulation than a combined film of Tedla (0.038 mm)/PET (0.051 mm)/EVA (0.55 mm). When formulated with a white pigment, reflectivity was comparable to Tedlar{trademark}. Upon accelerated exposure to light at 60C and 60% RH it was found that an EVA layer in front of these materials would decompose before significant yellowing and delamination of the back EPDM layer occurs.« less

Astronaut Ronald Evans is suited up for EVA training

NASA Technical Reports Server (NTRS)

1972-01-01

Astronaut Ronald E. Evans, command module pilot of the Apollo 17 lunar landing mission, is assisted by technicians in suiting up for extravehicular activity (EVA) training in a water tank in bldg 5 at the Manned Spacecraft Center (49970); Evans participates in EVA training in a water tank in bldg 5 at the Manned Spacecraft Center. The structure in the picture simulates the Scientific Instrument Module (SIM) bay of the Apollo 17 Service Module (49971).

Russian EVA 36

NASA Image and Video Library

2013-11-09

ISS037-E-028569 (9 Nov. 2013) --- Russian cosmonaut Oleg Kotov, Expedition 37 flight engineer, attired in a Russian Orlan spacesuit, uses a still camera during a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Kotov and Russian cosmonaut Sergey Ryazanskiy (out of frame) continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22.

Phillips during EVA

NASA Image and Video Library

2005-08-18

ISS011-E-11944 (18 August 2005) --- Attired in a Russian Orlan spacesuit, astronaut John L. Phillips, Expedition 11 NASA science officer and flight engineer, participates in a session of extravehicular activity (EVA). The 4 hour 58 minute spacewalk by Phillips and cosmonaut Sergei K. Krikalev (out of frame), commander representing Russia's Federal Space Agency, was the 62nd EVA in support of station assembly and maintenance, the 34th conducted from the station itself, and the 16th from the Pirs Docking Compartment.

EVA: Evryscopes for the Arctic and Antarctic

NASA Astrophysics Data System (ADS)

Richichi, A.; Law, N.; Tasuya, O.; Fors, O.; Dennihy, E.; Carlberg, R.; Tuthill, P.; Ashley, M.; Soonthornthum, B.

2017-06-01

We are planning to build Evryscopes for the Arctic and Antarctic (EVA), which will enable the first ultra-wide-field, high-cadence sky survey to be conducted from both Poles. The system is based on the successful Evryscope concept, already installed and operating since 2015 at Cerro Tololo in Chile with the following characteristics: robotic operation, 8,000 square degrees simultaneous sky coverage, 2-minute cadence, milli-mag level photometric accuracy, pipelined data processing for real-time analysis and full data storage for off-line analysis. The initial location proposed for EVA is the PEARL station on Ellesmere island; later also an antarctic location shall be selected. The science goals enabled by this unique combination of almost full-sky coverage and high temporal cadence are numerous, and include among others ground-breaking forays in the fields of exoplanets, stellar variability, asteroseismology, supernovae and other transient events. The EVA polar locations will enable uninterrupted observations lasting in principle over weeks and months. EVA will be fully robotic. We discuss the EVA science drivers and expected results, and present the logistics and the outline of the project which is expected to have first light in the winter of 2018. The cost envelope can be kept very competitive thanks to R&D already employed for the CTIO Evryscope, to our experience with both Arctic and Antarctic locations, and to the use of off-the-shelf components.

Computational simulation of extravehicular activity dynamics during a satellite capture attempt.

PubMed

Schaffner, G; Newman, D J; Robinson, S K

2000-01-01

A more quantitative approach to the analysis of astronaut extravehicular activity (EVA) tasks is needed because of their increasing complexity, particularly in preparation for the on-orbit assembly of the International Space Station. Existing useful EVA computer analyses produce either high-resolution three-dimensional computer images based on anthropometric representations or empirically derived predictions of astronaut strength based on lean body mass and the position and velocity of body joints but do not provide multibody dynamic analysis of EVA tasks. Our physics-based methodology helps fill the current gap in quantitative analysis of astronaut EVA by providing a multisegment human model and solving the equations of motion in a high-fidelity simulation of the system dynamics. The simulation work described here improves on the realism of previous efforts by including three-dimensional astronaut motion, incorporating joint stops to account for the physiological limits of range of motion, and incorporating use of constraint forces to model interaction with objects. To demonstrate the utility of this approach, the simulation is modeled on an actual EVA task, namely, the attempted capture of a spinning Intelsat VI satellite during STS-49 in May 1992. Repeated capture attempts by an EVA crewmember were unsuccessful because the capture bar could not be held in contact with the satellite long enough for the capture latches to fire and successfully retrieve the satellite.

Easy Volcanic Aerosol (EVA v1.0): an idealized forcing generator for climate simulations

NASA Astrophysics Data System (ADS)

Toohey, Matthew; Stevens, Bjorn; Schmidt, Hauke; Timmreck, Claudia

2016-11-01

Stratospheric sulfate aerosols from volcanic eruptions have a significant impact on the Earth's climate. To include the effects of volcanic eruptions in climate model simulations, the Easy Volcanic Aerosol (EVA) forcing generator provides stratospheric aerosol optical properties as a function of time, latitude, height, and wavelength for a given input list of volcanic eruption attributes. EVA is based on a parameterized three-box model of stratospheric transport and simple scaling relationships used to derive mid-visible (550 nm) aerosol optical depth and aerosol effective radius from stratospheric sulfate mass. Precalculated look-up tables computed from Mie theory are used to produce wavelength-dependent aerosol extinction, single scattering albedo, and scattering asymmetry factor values. The structural form of EVA and the tuning of its parameters are chosen to produce best agreement with the satellite-based reconstruction of stratospheric aerosol properties following the 1991 Pinatubo eruption, and with prior millennial-timescale forcing reconstructions, including the 1815 eruption of Tambora. EVA can be used to produce volcanic forcing for climate models which is based on recent observations and physical understanding but internally self-consistent over any timescale of choice. In addition, EVA is constructed so as to allow for easy modification of different aspects of aerosol properties, in order to be used in model experiments to help advance understanding of what aspects of the volcanic aerosol are important for the climate system.

EVA Retriever Demonstration

NASA Technical Reports Server (NTRS)

1988-01-01

The EVA retriever is demonstrated in the Manipulator Development Facility (MDF). The retriever moves on the air bearing table 'searching' for its target, in this case tools 'dropped' by astronauts on orbit.

Williams during EVA 36

NASA Image and Video Library

2016-08-19

Extravehicular crewmember 1 (EV1) Jeff Williams pauses for a photo after installing a Hemispherical (Hemi) Reflector Cover on Pressurized Mating Adapter 2 (PMA-2) during Extravehicular Activity 36 (EVA 36).

802.16e System Profile for NASA Extra-Vehicular Activities

NASA Technical Reports Server (NTRS)

Foore, Lawrence R.; Chelmins, David T.; Nguyen, Hung D.; Downey, Joseph A.; Finn, Gregory G.; Cagley, Richard E.; Bakula, Casey J.

2009-01-01

This report identifies an 802.16e system profile that is applicable to a lunar surface wireless network, and specifically for meeting extra-vehicular activity (EVA) data flow requirements. EVA suit communication needs are addressed. Design-driving operational scenarios are considered. These scenarios are then used to identify a configuration of the 802.16e system (system profile) that meets EVA requirements, but also aim to make the radio realizable within EVA constraints. Limitations of this system configuration are highlighted. An overview and development status is presented by Toyon Research Corporation concerning the development of an 802.16e compatible modem under NASA s Small Business Innovative Research (SBIR) Program. This modem is based on the recommended system profile developed as part of this report. Last, a path forward is outlined that presents an evolvable solution for the EVA radio system and lunar surface radio networks. This solution is based on a custom link layer, and 802.16e compliant physical layer compliant to the identified system profile, and a later progression to a fully interoperable 802.16e system.

Examination of a Standardized Test for Evaluating the Degree of Cure of EVA Encapsulation (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, D.; Wohlgemuth, J.; Gu, X.

2013-11-01

The curing of cross-linkable encapsulation is a critical consideration for photovoltaic (PV) modules manufactured using a lamination process. Concerns related to ethylene-co-vinyl acetate (EVA) include the quality (e.g., expiration and uniformity) of the films or completion (duration) of the cross-linking of the EVA within a laminator. Because these issues are important to both EVA and module manufacturers, an international standard has recently been proposed by the Encapsulation Task-Group within the Working Group 2 (WG2) of the International Electrotechnical Commission (IEC) Technical Committee 82 (TC82) for the quantification of the degree of cure for EVA encapsulation. The present draft of themore » standard calls for the use of differential scanning calorimetry (DSC) as the rapid, enabling secondary (test) method. Both the residual enthalpy- and melt/freeze-DSC methods are identified. The DSC methods are calibrated against the gel content test, the primary (reference) method. Aspects of other established methods, including indentation and rotor cure metering, were considered by the group. Key details of the test procedure will be described.« less

Is a multivalent hand, foot, and mouth disease vaccine feasible?

PubMed Central

Klein, Michel; Chong, Pele

2015-01-01

Enterovirus A infections are the primary cause of hand, foot and mouth disease (HFMD) in infants and young children. Although enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) are the predominant causes of HFMD epidemics worldwide, EV-A71 has emerged as a major neurovirulent virus responsible for severe neurological complications and fatal outcomes. HFMD is a serious health threat and economic burden across the Asia-Pacific region. Inactivated EV-A71 vaccines have elicited protection against EV-A71 but not against CV-A16 infections in large efficacy trials. The current development of a bivalent inactivated EV-A71/CV-A16 vaccine is the next step toward that of multivalent HFMD vaccines. These vaccines should ultimately include other prevalent pathogenic coxsackieviruses A (CV-A6 and CV-A10), coxsackieviruses B (B3 and B5) and echovirus 30 that often co-circulate during HFMD epidemics and can cause severe HFMD, aseptic meningitis and acute viral myocarditis. The prospect and challenges for the development of such multivalent vaccines are discussed. PMID:26009802

Impact of genetic changes, pathogenicity and antigenicity on Enterovirus- A71 vaccine development.

PubMed

Yee, Pinn Tsin Isabel; Laa Poh, Chit

2017-06-01

Enterovirus-A71 (EV-A71) is an etiological agent of the hand, foot and mouth disease (HFMD). EV-A71 infection produces high fever and ulcers in children. Some EV-A71 strains produce severe infections leading to pulmonary edema and death. Although the protective efficacy of the inactivated vaccine (IV) was ≥90% against mild HFMD, there was approximately 80% protection against severe HFMD. The monovalent EV-A71 IV elicits humoral immunity but lacks long-term immunogenicity. Spontaneous mutations of the EV-A71 genome could lead to antigenicity changes and the virus may not be neutralized by antibodies elicited by the IV. A better alternative would be the live attenuated vaccine (LAV) that elicits cellular and humoral immunity. The LAV induces excellent antigenicity and chances of reversion is reduced by presence of multiple mutations which could reduce pathogenicity. Besides CV-A16, outbreaks have been caused by CV-A6 and CV-A10, hence the development of bivalent and trivalent vaccines is required. Copyright © 2017 Elsevier Inc. All rights reserved.

Property tuning of poly(lactic acid)/cellulose bio-composites through blending with modified ethylene-vinyl acetate copolymer.

PubMed

Pracella, Mariano; Haque, Md Minhaz-Ul; Paci, Massimo; Alvarez, Vera

2016-02-10

The effect of addition of an ethylene-vinyl acetate copolymer modified with glycidyl methacrylate (EVA-GMA) on the structure and properties of poly(lactic acid) (PLA) composites with cellulose micro fibres (CF) was investigated. Binary (PLA/CF) and ternary (PLA/EVA-GMA/CF) composites obtained by melt mixing in Brabender mixer were analysed by SEM, POM, WAXS, DSC, TGA and tensile tests. The miscibility and morphology of PLA/EVA-GMA blends were first examined as a function of composition: a large rise of PLA spherulite growth rate in the blends was discovered with increasing the EVA-GMA content (0-30 wt%) in the isothermal crystallization both from the melt and the solid state. PLA/EVA-GMA/CF ternary composites displayed improved adhesion and dispersion of fibres into the matrix as compared to PLA/CF system. Marked changes of thermodynamic and tensile parameters, as elastic modulus, strength and elongation at break were observed for the composites, depending on blend composition, polymer miscibility and fibre-matrix chemical interactions at the interface. Copyright © 2015 Elsevier Ltd. All rights reserved.

Occurrence of simultaneous cathodal-anodal capture with left ventricular quadripolar leads for cardiac resynchronization therapy: an electrocardiogram evaluation.

PubMed

Occhetta, Eraldo; Dell'Era, Gabriele; Giubertoni, Ailia; Magnani, Andrea; Rametta, Francesco; Blandino, Alessandro; Magnano, Vincenzo; Malacrida, Maurizio; Marino, Paolo

2017-04-01

The occurrence of left ventricular (LV) anodal activation during pacing with modern multipolar cardiac resynchronization therapy (CRT) systems has never been reported. The aim of our study was to demonstrate, by means of electrocardiogram (ECG) analysis, the occurrence of simultaneous cathodal-anodal LV capture with quadripolar LV leads. We studied 10 first-time recipients of a CRT device equipped with a quadripolar LV lead. During follow-up, standard supine 12-lead ECGs were obtained in available cathode-to-anode LV pacing configurations with a pulse amplitude equal to twice the pacing threshold. The occurrence of simultaneous cathodal-anodal LV capture was defined as the presence of variations in electrocardiographic ventricular activation (EVA) when the distal tip (cathode)-to-device can (anode) pacing configuration was compared with the distal tip (cathode)-to-proximal ring (anode) configuration. In eight patients, we found differences in EVA when different LV sites were paced through the unipolar LV tip and unipolar LV ring configurations. In these patients, a difference in EVA was detected in 61.5% (59 of 96) of the ECG leads (marked difference in 31.3%, slight difference in 30.2%). Changes in EVA between unipolar tip-to-can and bipolar tip-to-ring pacing that were suggestive of cathodal-anodal LV capture were found in six patients. In these patients, a total of 30 (41.7%) ECG leads showed a difference in EVA (marked difference in 20.8%, slight difference in 20.8%). In our experience, additional anodal capture by the proximal LV ring during LV pacing is provable in most recipients of a resynchronization device equipped with a multipolar LV lead. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

STS-103 crewmembers during NBL EVA training

NASA Image and Video Library

1999-06-21

S99-06194 (21 June 1999) --- Astronaut C. Michael Foale, mission specialist, rehearses Extravehicular Activity (EVA) with the Hubble Space Telescope (HST) mockup in the Neutral Buoyancy Laboratory (NBL).

Using Analogs for Performance Testing of Humans in Spacesuits in Simulated Reduced Gravity

NASA Technical Reports Server (NTRS)

Norcross, Jason R.

2013-01-01

In general metabolic rates tend to be higher in NBL than in flight: a) Restraint method dependant; b) Significant differences between the NBL and flight for BRT and APFR (buoyancy effects). c) No significant difference between NBL and flight for free float and SRMS/SSRMS operations. The total metabolic energy expenditure for a given task and for the EVA as a whole are similar between NBL and flight: a) NBL metabolic rates are higher, but training EVAs are constrained to 5 1/2 hours. b) Flight metabolic rates are lower, but the EVAs are typically an hour or more longer in duration. NBL metabolic rates provide a useful operational tool for flight planning. Quantifying differences and similarities between training and flight improves knowledge for preparation of safe and efficient EVAs.

Metabolic Expenditures During Extravehicular Activity: Spaceflight versus Ground-based Simulation

NASA Technical Reports Server (NTRS)

Klein, Jill; Conkin, Johnny; Gernhardt, Michael; Srinivasan, Ramachandra

2008-01-01

In general metabolic rates tend to be higher in NBL than in flight: a) Restraint method dependent; b) Significant differences between the NBL and flight for BRT and APFR (buoyancy effects); and c) No significant difference between NBL and flight for free float and SRMS/SSRMS operations. The total metabolic energy expenditure for a given task and for the EVA as a whole are similar between NBL and flight: a) NBL metabolic rates are higher, but training EVAs are constrained to 5 hours; and b) Flight metabolic rates are lower, but the EVAs are typically an hour or more longer in duration. NBL metabolic rates provide a useful operational tool for flight planning. Quantifying differences and similarities between training and flight improves knowledge for preparation of safe and efficient EVAs.

Prevention of decompression sickness during extravehicular activity in space: a review.

PubMed

Tokumaru, O

1997-12-01

Extended and more frequent extravehicular activity (EVA) is planned in NASA's future space programs. The more EVAs are conducted, the higher the incidence of decompression sickness (DCS) that is anticipated. Since Japan is also promoting the Space Station Freedom project with NASA, DCS during EVA will be an inevitable complication. The author reviewed the pathophysiology of DCS and detailed four possible ways of preventing decompression sickness during EVA in space: (1) higher pressure suit technology; (2) preoxygenation/prebreathing; (3) staged decompression; and (4) habitat or vehicle pressurization. Among these measures, development of zero-prebreathe higher pressure suit technology seems most ideal, but because of economic and technical reasons and in cases of emergency, other methods must also be improved. Unsolved problems like repeated decompression or oxygen toxicity were also listed.

Evolution and Spatiotemporal Dynamics of Enterovirus A71 Subgenogroups in Vietnam.

PubMed

Thao, Nguyen Thi Thanh; Donato, Celeste; Trang, Vu Thi Huyen; Kien, Nguyen Trung; Trang, Ph M Mai Thuy; Khanh, Tran Quoc; Nguyet, Dang Thi; Sessions, October M; Cuong, Hoang Quoc; Lan, Phan Trong; Huong, Vu Thi Que; van Doorn, H Rogier; Vijaykrishna, Dhanasekaran

2017-12-12

Enterovirus A71 (EV-A71) is the major cause of severe hand, foot, and mouth disease and viral encephalitis in children across the Asia-Pacific region, including in Vietnam, which has experienced a high burden of disease in recent years. Multiple subgenogroups (C1, C4, C5, and B5) concurrently circulate in the region with a large variation in epidemic severity. The relative differences in their evolution and epidemiology were examined within Vietnam and globally. A total of 752 VP1 gene sequences were analyzed (413 generated in this study combined with 339 obtained from GenBank), collected from patients in 36 provinces in Vietnam during 2003-2013, along with epidemiological metadata. Globally representative VP1 gene datasets of subgenogroups were used to coestimate time-resolved phylogenies and relative genetic diversity to infer virus origins and regional transmission network. Despite frequent virus migration between countries, the highest genetic diversity of individual subgenogroups was maintained independently for several years in specific Asian countries representing genogroup-specific sources of EV-A71 diversity. This study highlights a persistent transmission network of EV-A71, with specific Asian countries seeding other countries in the region and beyond, emphasizing the need for improved EV-A71 surveillance and detailed genetic and antigenic characterization. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Photos taken inside ISS during EVA day

NASA Image and Video Library

2013-07-09

Astronaut Karen Nyberg,Expedition 36 flight engineer,is photographed at the Space Station Remote Manipulator System (SSRMS) controls in the U.S. Laboratory during a session of extravehicular activity (EVA).

Go for EVA!

NASA Technical Reports Server (NTRS)

1995-01-01

In this educational video series, 'Liftoff to Learning', astronauts from the STS-37 Space Shuttle Mission (Jay Apt, Jerry Ross, Ken Cameron, Steve Nagel, and Linda Godwin) show what EVA (extravehicular activity) means, talk about the history and design of the space suits and why they are designed the way they are, describe different ways they are used (payload work, testing and maintenance of equipment, space environment experiments) in EVA work, and briefly discuss the future applications of the space suits. Computer graphics and animation is included.

Application of EVA guidelines and design criteria. Volume 1: EVA selection/systems design considerations

NASA Technical Reports Server (NTRS)

Brown, N. E.

1973-01-01

Parameters that require consideration by the planners and designers when planning for man to perform functions outside the vehicle are presented in terms of the impact the extravehicular crewmen and major EV equipment items have on the mission, vehicle, and payload. Summary data on man's performance capabilities in the weightless space environment are also provided. The performance data are based on orbital and transearth EVA from previous space flight programs and earthbound simulations, such as water immersion and zero-g aircraft.

ASTRONAUT KERWIN, JOSEPH P. - EXTRAVEHICULAR ACTIVITY (EVA) - SKYLAB (SL)-2

NASA Image and Video Library

1973-06-01

S73-27562 (June 1973) --- Scientist-astronaut Joseph P. Kerwin, Skylab 2 science pilot, performs extravehicular activity (EVA) at the Skylab 1 and 2 space station cluster in Earth orbit, as seen in this reproduction taken from a color television transmission made by a TV camera aboard the station. Kerwin is just outside the Airlock Module. Kerwin assisted astronaut Charles Conrad Jr., Skylab 2 commander, during the successful EVA attempt to free the stuck solar array system wing on the Orbital Workshop. Photo credit: NASA

Phillips during EVA

NASA Image and Video Library

2005-08-18

ISS011-E-11948 (18 August 2005) --- Attired in a Russian Orlan spacesuit, astronaut John L. Phillips, Expedition 11 NASA Space Station science officer and flight engineer, participates in a session of extravehicular activity (EVA). The 4 hour 58 minute spacewalk by Phillips and cosmonaut Sergei K. Krikalev (seen in Phillip’;s helmet visor), commander representing Russia's Federal Space Agency, was the 62nd EVA in support of Station assembly and maintenance, the 34th conducted from the Station itself, and the 16th from the Pirs Docking Compartment.

Phillips during EVA

NASA Image and Video Library

2005-08-18

ISS011-E-11949 (18 August 2005) --- Attired in a Russian Orlan spacesuit, astronaut John L. Phillips, Expedition 11 NASA Space Station science officer and flight engineer, participates in a session of extravehicular activity (EVA). The 4 hour 58 minute spacewalk by Phillips and cosmonaut Sergei K. Krikalev (seen in Phillip’;s helmet visor), commander representing Russia's Federal Space Agency, was the 62nd EVA in support of Station assembly and maintenance, the 34th conducted from the Station itself, and the 16th from the Pirs Docking Compartment.

Phillips during EVA

NASA Image and Video Library

2005-08-18

ISS011-E-11947 (18 August 2005) --- Attired in a Russian Orlan spacesuit, astronaut John L. Phillips, Expedition 11 NASA Space Station science officer and flight engineer, participates in a session of extravehicular activity (EVA). The 4 hour 58 minute spacewalk by Phillips and cosmonaut Sergei K. Krikalev (seen in Phillip’;s helmet visor), commander representing Russia's Federal Space Agency, was the 62nd EVA in support of Station assembly and maintenance, the 34th conducted from the Station itself, and the 16th from the Pirs Docking Compartment.

Russian EVA 36

NASA Image and Video Library

2013-11-09

ISS037-E-028787 (9 Nov. 2013) --- Russian cosmonauts Oleg Kotov (left) and Sergey Ryazanskiy, both Expedition 37 flight engineers, attired in Russian Orlan spacesuits, participate in a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Kotov and Ryazanskiy continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22. Earth’s horizon and the blackness of space provide the backdrop for the scene.

Phillips during EVA

NASA Image and Video Library

2005-08-18

ISS011-E-11958 (18 August 2005) --- Attired in a Russian Orlan spacesuit, astronaut John L. Phillips, Expedition 11 NASA Space Station science officer and flight engineer, participates in a session of extravehicular activity (EVA). The 4 hour 58 minute spacewalk by Phillips and cosmonaut Sergei K. Krikalev (out of frame), commander representing Russia's Federal Space Agency, was the 62nd EVA in support of Station assembly and maintenance, the 34th conducted from the Station itself, and the 16th from the Pirs Docking Compartment.

CREW TRAINING (EXTRAVEHICULAR ACTIVITY [EVA]) - STS-41G - JSC

NASA Image and Video Library

1984-07-06

S84-36956 (1 July 1984) --- Astronaut Robert L. Crippen, 41-G crew commander, prepares his SCUBA mask prior to submerging into the weightless environment training facility's 25 ft. deep pool to observe a simulation exercise for two fellow 41-G crewmembers assigned to an extravehicular activity (EVA) in space. Not pictured are Astronauts Kathryn D. Sullivan and David C. Leestma, mission specialists who will perform the EVA during the eight-day mission scheduled for October of this year.

EV-A71 vaccine licensure: a first step for multivalent enterovirus vaccine to control HFMD and other severe diseases

PubMed Central

Mao, Qunying; Wang, Yiping; Bian, Lianlian; Xu, Miao; Liang, Zhenglun

2016-01-01

Enteroviruses (EVs) are the most common viral agents in humans. Although most infections are mild or asymptomatic, there is a wide spectrum of clinical manifestations that may be caused by EV infections with varying degrees of severity. Among these viruses, EV-A71 and coxsackievirus (CV) CV-A16 from group A EVs attract the most attention because they are responsible for hand, foot and mouth disease (HFMD). Other EV-A viruses such as CV-A6 and CV-A10 were also reported to cause HFMD outbreaks in several countries or regions. Group B EVs such as CV-B3, CV-B5 and echovirus 30 were reported to be the main pathogens responsible for myocarditis and encephalitis epidemics and were also detected in HFMD patients. Vaccines are the best tools to control infectious diseases. In December 2015, China's Food and Drug Administration approved two inactivated EV-A71 vaccines for preventing severe HFMD.The CV-A16 vaccine and the EV-A71-CV-A16 bivalent vaccine showed substantial efficacy against HFMD in pre-clinical animal models. Previously, research on EV-B group vaccines was mainly focused on CV-B3 vaccine development. Because the HFMD pathogen spectrum has changed, and the threat from EV-B virus-associated severe diseases has gradually increased, it is necessary to develop multivalent HFMD vaccines. This study summarizes the clinical symptoms of diseases caused by EVs, such as HFMD, myocarditis and encephalitis, and the related EV vaccine development progress. In conclusion, developing multivalent EV vaccines should be strongly recommended to prevent HFMD, myocarditis, encephalitis and other severe diseases. PMID:27436364

The use of an extended ventilation tube as a countermeasure for EVA-associated upper extremity medical issues

NASA Astrophysics Data System (ADS)

Jones, J. A.; Hoffman, R. B.; Buckland, D. A.; Harvey, C. M.; Bowen, C. K.; Hudy, C. E.; Strauss, S.; Novak, J.; Gernhardt, M. L.

Introduction: Onycholysis due to repetitive activity in the space suit glove during Neutral Buoyancy Laboratory (NBL) training and during spaceflight extravehicular activity (EVA) is a common observation. Moisture accumulates in gloves during EVA task performance and may contribute to the development of pain and damage to the fingernails experienced by many astronauts. The study evaluated the use of a long ventilation tube to determine if improved gas circulation into the hand area could reduce hand moisture and thereby decrease the associated symptoms. Methods: The current Extravehicular Mobility Unit (EMU) was configured with a ventilation tube that extended down a single arm of the crew member (E) and compared with the unventilated arm (C). Skin surface moisture was measured on both hands immediately after glove removal and a questionnaire administered to determine subjective measures. Astronauts ( n=6) were examined pre- and post-run. Results: There were consistent trends in the reduction of relative hydration ratios at dorsum ( C=3.34, E=2.11) and first ring finger joint ( C=2.46, E=1.96) when the ventilation tube was employed. Ventilation appeared more effective on the left versus the right hand, implying an interaction with hand anthropometry and glove fit. Symptom score was lower on the hand that had the long ventilation tube relative to the control hand in 2/6 EVA crew members. Conclusions: Increased ventilation to the hand was effective in reducing the risks of hand and nail discomfort symptoms from moderate to low in one-third of the subjects. Improved design in the ventilation capability of EVA spacesuits is expected to improve efficiency of air flow distribution.

EV-A71 vaccine licensure: a first step for multivalent enterovirus vaccine to control HFMD and other severe diseases.

PubMed

Mao, Qunying; Wang, Yiping; Bian, Lianlian; Xu, Miao; Liang, Zhenglun

2016-07-20

Enteroviruses (EVs) are the most common viral agents in humans. Although most infections are mild or asymptomatic, there is a wide spectrum of clinical manifestations that may be caused by EV infections with varying degrees of severity. Among these viruses, EV-A71 and coxsackievirus (CV) CV-A16 from group A EVs attract the most attention because they are responsible for hand, foot and mouth disease (HFMD). Other EV-A viruses such as CV-A6 and CV-A10 were also reported to cause HFMD outbreaks in several countries or regions. Group B EVs such as CV-B3, CV-B5 and echovirus 30 were reported to be the main pathogens responsible for myocarditis and encephalitis epidemics and were also detected in HFMD patients. Vaccines are the best tools to control infectious diseases. In December 2015, China's Food and Drug Administration approved two inactivated EV-A71 vaccines for preventing severe HFMD.The CV-A16 vaccine and the EV-A71-CV-A16 bivalent vaccine showed substantial efficacy against HFMD in pre-clinical animal models. Previously, research on EV-B group vaccines was mainly focused on CV-B3 vaccine development. Because the HFMD pathogen spectrum has changed, and the threat from EV-B virus-associated severe diseases has gradually increased, it is necessary to develop multivalent HFMD vaccines. This study summarizes the clinical symptoms of diseases caused by EVs, such as HFMD, myocarditis and encephalitis, and the related EV vaccine development progress. In conclusion, developing multivalent EV vaccines should be strongly recommended to prevent HFMD, myocarditis, encephalitis and other severe diseases.

Design Considerations for a Crewed Mars Ascent Vehicle

NASA Technical Reports Server (NTRS)

Rucker, Michelle A.

2015-01-01

Exploration architecture studies identified the Mars Ascent Vehicle (MAV) as one of the largest "gear ratio" items in a crewed Mars mission. Because every kilogram of mass ascended from the Martian surface requires seven kilograms or more of ascent propellant, it is desirable for the MAV to be as small and lightweight as possible. Analysis identified four key factors that drive MAV sizing: 1) Number of crew: more crew members require more equipment-and a larger cabin diameter to hold that equipment-with direct implications to structural, thermal, propulsion, and power subsystem mass. 2) Which suit is worn during ascent: Extravehicular Activity (EVA) type suits are physically larger and heavier than Intravehicular Activity (IVA) type suits and because they are less flexible, EVA suits require more elbow-room to maneuver in and out of. An empty EVA suit takes up about as much cabin volume as a crew member. 3) How much time crew spends in the MAV: less than about 12 hours and the MAV can be considered a "taxi" with few provisions for crew comfort. However, if the crew spends more than 12 consecutive hours in the MAV, it begins to look like a Habitat requiring more crew comfort items. 4) How crew get into/out of the MAV: ingress/egress method drives structural mass (for example, EVA hatch vs. pressurized tunnel vs. suit port) as well as consumables mass for lost cabin atmosphere, and has profound impacts on surface element architecture. To minimize MAV cabin mass, the following is recommended: Limit MAV usage to 24 consecutive hours or less; discard EVA suits on the surface and ascend wearing IVA suits; Limit MAV functionality to ascent only, rather than dual-use ascent/habitat functions; and ingress/egress the MAV via a detachable tunnel to another pressurized surface asset.

Extreme value analysis of the time derivative of the horizontal magnetic field and computed electric field

NASA Astrophysics Data System (ADS)

Wintoft, Peter; Viljanen, Ari; Wik, Magnus

2016-05-01

High-frequency ( ≈ minutes) variability of ground magnetic fields is caused by ionospheric and magnetospheric processes driven by the changing solar wind. The varying magnetic fields induce electrical fields that cause currents to flow in man-made conductors like power grids and pipelines. Under extreme conditions the geomagnetically induced currents (GIC) may be harmful to the power grids. Increasing our understanding of the extreme events is thus important for solar-terrestrial science and space weather. In this work 1-min resolution of the time derivative of measured local magnetic fields (|dBh/dt|) and computed electrical fields (Eh), for locations in Europe, have been analysed with extreme value analysis (EVA). The EVA results in an estimate of the generalized extreme value probability distribution that is described by three parameters: location, width, and shape. The shape parameter controls the extreme behaviour. The stations cover geomagnetic latitudes from 40 to 70° N. All stations included in the study have contiguous coverage of 18 years or more with 1-min resolution data. As expected, the EVA shows that the higher latitude stations have higher probability of large |dBh/dt| and |Eh| compared to stations further south. However, the EVA also shows that the shape of the distribution changes with magnetic latitude. The high latitudes have distributions that fall off faster to zero than the low latitudes, and upward bounded distributions can not be ruled out. The transition occurs around 59-61° N magnetic latitudes. Thus, the EVA shows that the observed series north of ≈ 60° N have already measured values that are close to the expected maxima values, while stations south of ≈ ° N will measure larger values in the future.

EVA 25

NASA Image and Video Library

2013-12-24

View of Rick Mastracchio,in his Extravehicular Mobility Unit (EMU),working to mate spare Pump Module (PM) Quick Disconnects (QDs) during International Space Station (ISS) Extravehicular Activity (EVA) 25. Image was released by astronaut on Twitter.

The exercise and environmental physiology of extravehicular activity

NASA Technical Reports Server (NTRS)

Cowell, Stephenie A.; Stocks, Jodie M.; Evans, David G.; Simonson, Shawn R.; Greenleaf, John E.

2002-01-01

Extravehicular activity (EVA), i.e., exercise performed under unique environmental conditions, is indispensable for supporting daily living in weightlessness and for further space exploration. From 1965-1996 an average of 20 h x yr(-1) were spent performing EVA. International Space Station (ISS) assembly will require 135 h x yr(-1) of EVA, and 138 h x yr(-1) is planned for post-construction maintenance. The extravehicular mobility unit (EMU), used to protect astronauts during EVA, has a decreased pressure of 4.3 psi that could increase astronauts' risk of decompression sickness (DCS). Exercise in and repeated exposure to this hypobaria may increase the incidence of DCS, although weightlessness may attenuate this risk. Exercise thermoregulation within the EMU is poorly understood; the liquid cooling garment (LCG), worn next to the skin and designed to handle thermal stress, is manually controlled. Astronauts may become dehydrated (by up to 2.6% of body weight) during a 5-h EVA, further exacerbating the thermoregulatory challenge. The EVA is performed mainly with upper body muscles; but astronauts usually exercise at only 26-32% of their upper body maximal oxygen uptake (VO2max). For a given ground-based work task in air (as opposed to water), the submaximal VO2 is greater while VO2max and metabolic efficiency are lower during ground-based arm exercise as compared with leg exercise, and cardiovascular responses to exercise and training are also different for arms and legs. Preflight testing and training, whether conducted in air or water, must account for these differences if ground-based data are extrapolated for flight requirements. Astronauts experience deconditioning during microgravity resulting in a 10-20% loss in arm strength, a 20-30% loss in thigh strength, and decreased lower-body aerobic exercise capacity. Data from ground-based simulations of weightlessness such as bed rest induce a 6-8% decrease in upper-body strength, a 10-16% loss in thigh extensor strength, and a 15-20% decrease in lower-body aerobic exercise capacity. Changes in EVA support systems and training based on a greater understanding of the physiological aspects of exercise in the EVA environment will help to insure the health, safety, and efficiency of working astronauts.

The exercise and environmental physiology of extravehicular activity.

PubMed

Cowell, Stephenie A; Stocks, Jodie M; Evans, David G; Simonson, Shawn R; Greenleaf, John E

2002-01-01

Extravehicular activity (EVA), i.e., exercise performed under unique environmental conditions, is indispensable for supporting daily living in weightlessness and for further space exploration. From 1965-1996 an average of 20 h x yr(-1) were spent performing EVA. International Space Station (ISS) assembly will require 135 h x yr(-1) of EVA, and 138 h x yr(-1) is planned for post-construction maintenance. The extravehicular mobility unit (EMU), used to protect astronauts during EVA, has a decreased pressure of 4.3 psi that could increase astronauts' risk of decompression sickness (DCS). Exercise in and repeated exposure to this hypobaria may increase the incidence of DCS, although weightlessness may attenuate this risk. Exercise thermoregulation within the EMU is poorly understood; the liquid cooling garment (LCG), worn next to the skin and designed to handle thermal stress, is manually controlled. Astronauts may become dehydrated (by up to 2.6% of body weight) during a 5-h EVA, further exacerbating the thermoregulatory challenge. The EVA is performed mainly with upper body muscles; but astronauts usually exercise at only 26-32% of their upper body maximal oxygen uptake (VO2max). For a given ground-based work task in air (as opposed to water), the submaximal VO2 is greater while VO2max and metabolic efficiency are lower during ground-based arm exercise as compared with leg exercise, and cardiovascular responses to exercise and training are also different for arms and legs. Preflight testing and training, whether conducted in air or water, must account for these differences if ground-based data are extrapolated for flight requirements. Astronauts experience deconditioning during microgravity resulting in a 10-20% loss in arm strength, a 20-30% loss in thigh strength, and decreased lower-body aerobic exercise capacity. Data from ground-based simulations of weightlessness such as bed rest induce a 6-8% decrease in upper-body strength, a 10-16% loss in thigh extensor strength, and a 15-20% decrease in lower-body aerobic exercise capacity. Changes in EVA support systems and training based on a greater understanding of the physiological aspects of exercise in the EVA environment will help to insure the health, safety, and efficiency of working astronauts.

Early Vascular Ageing - A Concept in Development.

PubMed

M Nilsson, Peter

2015-04-01

Cardiovascular disease (CVD) is a prevalent condition in the elderly, often associated with metabolic disturbance and type 2 diabetes. For a number of years, research dedicated to understand atherosclerosis dominated, and for many good reasons, this pathophysiological process being proximal to the CVD events. In recent years, research has been devoted to an earlier stage of vascular pathology named arteriosclerosis (arterial stiffness) and the new concept of early vascular ageing (EVA), developed by a group of mostly European researchers. This overview describes recent developments in research dedicated to EVA and new emerging aspects found in studies of families at high cardiovascular risk. There are new aspects related to genetics, telomere biology and the role of gut microbiota. However, there is still no unifying definition available of EVA and no direct treatment, but rather only recommendations for conventional cardiovascular risk factor control. New interventions are being developed - not only new antihypertensive drugs, but also new drugs for vascular protection - the selective angiotensin-II (AT2) agonist Compound 21 (C21). Human studies are eagerly awaited. Even new functional food products could have the potential to positively influence cardiometabolic regulation, to be confirmed.

Science Support Room Operations During Desert RATS 2009

NASA Technical Reports Server (NTRS)

Lofgren, G. E.; Horz, F.; Bell, M. S.; Cohen, B. A.; Eppler,D. B.; Evans, C. a.; Hodges, K. V.; Hynek, B. M.; Gruener, J. E.; Kring, D. A.;

Encapsulation Processing and Manufacturing Yield Analysis

NASA Technical Reports Server (NTRS)

Willis, P.

1985-01-01

Evaluation of the ethyl vinyl acetate (EVA) encapsulation system is presented. This work is part of the materials baseline needed to demonstrate a 30 year module lifetime capability. Process and compound variables are both being studied along with various module materials. Results have shown that EVA should be stored rolled up, and enclosed in a plastic bag to retard loss of peroxide curing agents. The TBEC curing agent has superior shelf life and processing than the earlier Lupersol-101 curing agent. Analytical methods were developed to test for peroxide content, and experimental methodologies were formalized.

Analytical study of electrical disconnect system for use on manned and unmanned missions

NASA Technical Reports Server (NTRS)

Rosener, A. A.; Lenda, J. A.; Trummer, R. O.; Jonkoniec, T. G.

1977-01-01

The program to survey existing electrical connector availability, and establish an optimum connector design for maintainable spacecraft substation interfaces is reported. Functional and operational requirements are given along with the results of the documentation survey, which disclosed that the MSFC series connectors have the preferred features of current connector technology. Optimum design concepts for EVA tasks, modules serviced by manipulators, and for manipulators independent of other servicing units are presented. It is concluded that separate connector designs are required for spacecraft replaceable modules, and for crewman EVA.

Russian EVA 33

NASA Image and Video Library

2013-06-24

View of Russian cosmonaut Alexander Misurkin (bottom center), Expedition 36 flight engineer, participating in Russian extravehicular activity (EVA) 33. Also visible are the Progress spacecraft docked to the Pirs Docking Compartment (DC1) with the Service Module (SM) .

In-Suit Light Exercise (ISLE) Prebreathe Protocol Peer Review Assessment. Part 2; Appendices

NASA Technical Reports Server (NTRS)

Brady, Timothy K.; Polk, James D.

2011-01-01

The performance of extravehicular activity (EVA) by National Aeronautics and Space Administration astronauts involves the risk of decompression sickness. This risk has been mitigated by the use of oxygen "prebreathe" to effectively wash out tissue nitrogen prior to each EVA. Now that the Space Shuttle Program (SSP) is being retired, high-pressure oxygen will become a limited resource. The In-Suit Light Exercise (ISLE) Prebreathe Protocol offers several potential benefits including its potential to save 6 pounds of oxygen per EVA. At the request of the NASA Engineering and Safety Center, the peer review convened on October 14, 2010. The major recommendation of the Review Committee was that the ISLE protocol was acceptable for operational use as a prebreathe option prior to EVA. The appendices to Volume I of the report are contained in this document.

In-Suit Light Exercise (ISLE) Prebreathe Protocol Peer Review Assessment. Volume 1

NASA Technical Reports Server (NTRS)

Brady, Timothy K.; Polk, James D.

2011-01-01

The performance of extravehicular activity (EVA) by National Aeronautics and Space Administration astronauts involves the risk of decompression sickness. This risk has been mitigated by the use of oxygen "prebreathe" to effectively wash out tissue nitrogen prior to each EVA. Now that the Space Shuttle Program (SSP) is being retired, high-pressure oxygen will become a limited resource. The In-Suit Light Exercise (ISLE) Prebreathe Protocol offers several potential benefits including its potential to save 6 pounds of oxygen per EVA. At the request of the NASA Engineering and Safety Center, the peer review convened on October 14, 2010. The major recommendation of the Review Committee was that the ISLE protocol was acceptable for operational use as a prebreathe option prior to EVA. The results from the peer review are contained in this document.

Verification of an altitude decompression sickness prevention protocol for Shuttle operations utilizing a 10.s psi pressure stage

NASA Technical Reports Server (NTRS)

Waligora, J. M.; Horrigan, D. J., Jr.; Conkin, J.; Hadley, A. T., III

1984-01-01

Three test series involving 173-man tess were conducted to define and verify a pre-extravehicular activity (EVA) denitrogenation procedure that would provide acceptable protection against altitude decompression sickness while minimizing the required duration of oxygen (O2) prebreathe in the suit prior to EVA. The tests also addressed the safety, in terms of incidence of decompression sickness, of conducting EVA's on consecutive days rather than on alternate days. The tests were conducted in an altitude chamber, subjects were selected as representative of the astronaut population, and EVA periods were simulated by reducing the chamber pressure to suit pressure while the subjects breathed O2 with masks and worked at EVA representative work rates. A higher than anticipated incidence of both venous bubbles (55%) and symptoms (26%) was measured following all denitrogenation protocols in this test. For the most part, symptoms were very minor and stabilized, diminished, or disappeared in the six-hour tests. Instances of clear, possible, or potential systemic symptoms were encountered only after use of the unmodified 10.2 psi protocol and not after the modified 10.2 psi protocol, the 3.5-hour O2 prebreathed protocol, or the 4.0-hour O2 prebreathe protocol. The high incidence of symptoms is ascribed to the type and duration of exercise and the sensitivity of the reporting technique to minor symptoms. Repeated EVA exposures after only 17 hours did not increase symptom or bubble incidence.

Comparison Of Human Modelling Tools For Efficiency Of Prediction Of EVA Tasks

NASA Technical Reports Server (NTRS)

Dischinger, H. Charles, Jr.; Loughead, Tomas E.

1998-01-01

Construction of the International Space Station (ISS) will require extensive extravehicular activity (EVA, spacewalks), and estimates of the actual time needed continue to rise. As recently as September, 1996, the amount of time to be spent in EVA was believed to be about 400 hours, excluding spacewalks on the Russian segment. This estimate has recently risen to over 1100 hours, and it could go higher before assembly begins in the summer of 1998. These activities are extremely expensive and hazardous, so any design tools which help assure mission success and improve the efficiency of the astronaut in task completion can pay off in reduced design and EVA costs and increased astronaut safety. The tasks which astronauts can accomplish in EVA are limited by spacesuit mobility. They are therefore relatively simple, from an ergonomic standpoint, requiring gross movements rather than time motor skills. The actual tasks include driving bolts, mating and demating electric and fluid connectors, and actuating levers; the important characteristics to be considered in design improvement include the ability of the astronaut to see and reach the item to be manipulated and the clearance required to accomplish the manipulation. This makes the tasks amenable to simulation in a Computer-Assisted Design (CAD) environment. For EVA, the spacesuited astronaut must have his or her feet attached on a work platform called a foot restraint to obtain a purchase against which work forces may be actuated. An important component of the design is therefore the proper placement of foot restraints.

From "Below Dignity" to "Above It All": Origins and Early History of Underwater Neutral Buoyancy Simulation of Weightlessness for EVA Procedures Development and Training

NASA Technical Reports Server (NTRS)

Charles, John B.

2013-01-01

An attempt to clarify some vague memories of underwater studies of astronaut capabilities in space led Dr. John Charles to become acquainted with Sam Mattingly, one of the pioneers in the field, and to greater insights into Mattingly's work simulating Gemini EVAs in the mid-1960s. Charles recounted major accomplishments by Environmental Research Associates (ERA), Mattingly's company for contracting with NASA Langley on several early studies. ERA's work was considered within the context of contemporary efforts to simulate weightlessness and the widespread development of neutral buoyancy facilities after ERA's successful demonstration for Gemini 12.

Evaluating the Benefits of Aphasia Intervention Delivered in Virtual Reality: Results of a Quasi-Randomised Study.

PubMed

Marshall, Jane; Booth, Tracey; Devane, Niamh; Galliers, Julia; Greenwood, Helen; Hilari, Katerina; Talbot, Richard; Wilson, Stephanie; Woolf, Celia

2016-01-01

This study evaluated an intervention for people with aphasia delivered in a novel virtual reality platform called EVA Park. EVA Park contains a number of functional and fantastic locations and allows for interactive communication between multiple users. Twenty people with aphasia had 5 weeks' intervention, during which they received daily language stimulation sessions in EVA Park from a support worker. The study employed a quasi randomised design, which compared a group that received immediate intervention with a waitlist control group. Outcome measures explored the effects of intervention on communication and language skills, communicative confidence and feelings of social isolation. Compliance with the intervention was also explored through attrition and usage data. There was excellent compliance with the intervention, with no participants lost to follow up and most (18/20) receiving at least 88% of the intended treatment dose. Intervention brought about significant gains on a measure of functional communication. Gains were achieved by both groups of participants, once intervention was received, and were well maintained. Changes on the measures of communicative confidence and feelings of social isolation were not achieved. Results are discussed with reference to previous aphasia therapy findings.

Evaluating the Benefits of Aphasia Intervention Delivered in Virtual Reality: Results of a Quasi-Randomised Study

PubMed Central

Marshall, Jane; Booth, Tracey; Devane, Niamh; Galliers, Julia; Greenwood, Helen; Hilari, Katerina; Talbot, Richard; Wilson, Stephanie; Woolf, Celia

2016-01-01

Introduction This study evaluated an intervention for people with aphasia delivered in a novel virtual reality platform called EVA Park. EVA Park contains a number of functional and fantastic locations and allows for interactive communication between multiple users. Twenty people with aphasia had 5 weeks’ intervention, during which they received daily language stimulation sessions in EVA Park from a support worker. The study employed a quasi randomised design, which compared a group that received immediate intervention with a waitlist control group. Outcome measures explored the effects of intervention on communication and language skills, communicative confidence and feelings of social isolation. Compliance with the intervention was also explored through attrition and usage data. Results There was excellent compliance with the intervention, with no participants lost to follow up and most (18/20) receiving at least 88% of the intended treatment dose. Intervention brought about significant gains on a measure of functional communication. Gains were achieved by both groups of participants, once intervention was received, and were well maintained. Changes on the measures of communicative confidence and feelings of social isolation were not achieved. Results are discussed with reference to previous aphasia therapy findings. PMID:27518188

Venous gas emboli and exhaled nitric oxide with simulated and actual extravehicular activity.

PubMed

Karlsson, Lars L; Blogg, S Lesley; Lindholm, Peter; Gennser, Mikael; Hemmingsson, Tryggve; Linnarsson, Dag

2009-10-01

The decompression experienced due to the change in pressure from a space vehicle (1013hPa) to that in a suit for extravehicular activity (EVA) (386hPa) was simulated using a hypobaric chamber. Previous ground-based research has indicated around a 50% occurrence of both venous gas emboli (VGE) and symptoms of decompression illness (DCI) after similar decompressions. In contrast, no DCI symptoms have been reported from past or current space activities. Twenty subjects were studied using Doppler ultrasound to detect any VGE during decompression to 386hPa, where they remained for up to 6h. Subjects were supine to simulate weightlessness. A large number of VGE were found in one subject at rest, who had a recent arm fracture; a small number of VGE were found in another subject during provocation with calf contractions. No changes in exhaled nitric oxide were found that can be related to either simulated EVA or actual EVA (studied in a parallel study on four cosmonauts). We conclude that weightlessness appears to be protective against DCI and that exhaled NO is not likely to be useful to monitor VGE.

[Role of Toll-like receptor 7 in the production of inflammatory cytokines in EV-A71-infected human Jurkat T cells].

PubMed

Chi, Jing; He, Yaqing; Yu, Guangqing; Lei, Lei

2016-03-01

To investigate the expression of Toll-like receptor (TLR) mRNA in enterovirus 71(EV-A71) infected human Jurkat T cells and clarify the role of TLRs in the pathogenesis of EV-A71 infection-induced inflammation. EV-A71 strains were isolated from feces of children patients with hand, foot and mouth disease in 2014 by Shenzhen Center for Disease Control and Prevention. Human Jurkat T cells were infected with 200 μl EV-A71 at 10(3) cell culture infective dose 50%(CCID50)/ml. The expression of TLR1-TLR10 mRNA in human Jurkat T cells was assessed at different exposure time by RT-PCR. Levels of TLR7 mRNA expression were detected by real-time PCR, and levels of myeloid differentiation factor 88 (MyD88) by western blot. The cytokine secretion of interleukin (IL)-6, IL-8 and Tumor Necrosis Factor α (TNF-α) was analyzed by ELISA assay. The relative expression level of TLR7 mRNA in human Jurkat T cells were 1.26 ± 0.15, 1.75 ± 0.20, 2.26 ± 0.23 and 3.74 ± 0.62 in 6, 12, 24 and 48 h after EV-A71 infection, which the differences were significant with mock-infected group(t values were -2.96, -6.38, -9.57, -7.71; P<0.05). Western blot showed that the protein expression levels of MyD88 had increased 1.34 times and 2.17 times in 24 h and 48 h after EV-A71 infection compared with mock-infected group. After infected for 24 h and 48 h, the levels of IL-6 were (302.86 ± 38.11), (179.70 ± 14.50) pg/ml, which were significantly higher than mock-infected group (176.42 ± 9.60), (179.70 ± 14.50) pg/ml (t values were -5.57, -18.54, P<0.05). The levels of TNF-α in EV-A71 infected group (100.81 ± 9.81) pg/ml was higher than that in mock-infected group (56.19 ± 6.94) pg/ml, and the difference was significant (t=-6.43, P=0.003). TLR7 is the main pattern recognition receptor responsible for EV-A71 recognition in immune cells, which then leads to the activation of TLR7 downstream signaling and the production of proinflammatory cytokines.

Evidence Report: Risk of Hypobaric Hypoxia from the Exploration Atmosphere

NASA Technical Reports Server (NTRS)

Norcross, Jason R.; Conkin, Johnny; Wessel, James H., III; Norsk, Peter; Law, Jennifer; Arias, Diana; Goodwin, Tom; Crucian, Brian; Whitmire, Alexandra; Bloomberg, Jacob;

Anthropometric specifications, development, and evaluation of EvaRID--a 50th percentile female rear impact finite element dummy model.

PubMed

Carlsson, Anna; Chang, Fred; Lemmen, Paul; Kullgren, Anders; Schmitt, Kai-Uwe; Linder, Astrid; Svensson, Mats Y

2014-01-01

Whiplash-associated disorders (WADs), or whiplash injuries, due to low-severity vehicle crashes are of great concern in motorized countries and it is well established that the risk of such injuries is higher for females than for males, even in similar crash conditions. Recent protective systems have been shown to be more beneficial for males than for females. Hence, there is a need for improved tools to address female WAD prevention when developing and evaluating the performance of whiplash protection systems. The objective of this study is to develop and evaluate a finite element model of a 50th percentile female rear impact crash test dummy. The anthropometry of the 50th percentile female was specified based on literature data. The model, called EvaRID (female rear impact dummy), was based on the same design concept as the existing 50th percentile male rear impact dummy, the BioRID II. A scaling approach was developed and the first version, EvaRID V1.0, was implemented. Its dynamic response was compared to female volunteer data from rear impact sled tests. The EvaRID V1.0 model and the volunteer tests compared well until ∼250 ms of the head and T1 forward accelerations and rearward linear displacements and of the head rearward angular displacement. Markedly less T1 rearward angular displacement was found for the EvaRID model compared to the female volunteers. Similar results were received for the BioRID II model when comparing simulated responses with experimental data under volunteer loading conditions. The results indicate that the biofidelity of the EvaRID V1.0 and BioRID II FE models have limitations, predominantly in the T1 rearward angular displacement, at low velocity changes (7 km/h). The BioRID II model was validated against dummy test results in a loading range close to consumer test conditions (EuroNCAP) and lower severity levels of volunteer testing were not considered. The EvaRID dummy model demonstrated the potential of becoming a valuable tool when evaluating and developing seats and whiplash protection systems. However, updates of the joint stiffness will be required to provide better correlation at lower load levels. Moreover, the seated posture, curvature of the spine, and head position of 50th percentile female occupants needs to be established and implemented in future models.

Human factors in space station architecture 2. EVA access facility: A comparative analysis of 4 concepts for on-orbit space suit servicing

NASA Technical Reports Server (NTRS)

Cohen, Marc M.; Bussolari, Steven

1987-01-01

Four concepts for on-orbit spacesuit donning, doffing, servicing, check-out, egress and ingress are presented. These are: the Space Transportation System (STS) Type (shuttle system enlarged), the Transit Airlock (Shuttle Airlock with suit servicing removed from the pump-down chamber), the Suitport (a rear-entry suit mates to a port in the airlock wall), and the Crewlock (a small, individual, conformal airlock). Each of these four concepts is compared through a series of seven steps representing a typical Extra Vehicular Activity (EVA) mission: (1) Predonning suit preparation; (2) Portable Life Support System (PLSS) preparation; (3) Suit Donning and Final Check; (4) Egress/Ingress; (5) Mid-EVA rest period; (6) Post-EVA Securing; (7) Non-Routine Maintenance. The different characteristics of each concept are articulated through this step-by-step approach. Recommendations concerning an approach for further evaluations of airlock geometry, anthropometrics, ergonomics, and functional efficiency are made. The key recommendation is that before any particular airlock can be designed, the full range of spacesuit servicing functions must be considered, including timelines that are most supportive of EVA human productivity.

Mobile colposcopy in urban and underserved suburban areas in Baja California

NASA Astrophysics Data System (ADS)

Madiedo, Marta; Contreras, Sonia; Villalobos, Octavio; Kahn, Bruce S.; Safir, Amit; Levitz, David

2016-03-01

Cervical cancer is the leading cause of cancer death for women in low resource settings, often affecting the most economically disenfranchised segment of the population. The key challenge with cervical cancer is the lack of an effective screening program for many of the at-risk, difficult-to-reach women. Outreach programs that utilize mobile clinics to increase access to screening and care in Baja California have been developed. However, many barriers such as quality assurance, efficient referral remained a challenge in this region. Visualization-based co-tests together with cytology (Pap smears) as a primary screen have been proposed. Here, the mobile colposcope of the enhanced visual assessment (EVA) is used to capture an image immediately following a Pap smear. EVA images were reviewed by expert colposcopists. Initial or preliminary data from pilot services showed that Pap false positives and Pap false negatives maybe reduced by expert review of EVA images. This suggests that reviewing of EVA images may be instrumental in catching inaccurate Pap results, thereby improving care. Thus, there is a need to further explore the benefits of using EVA as additional information when conducting Pap smear screenings.

Flame retardancy and thermal behavior of intumescent flame-retardant EVA composites with an efficient triazine-based charring agent

NASA Astrophysics Data System (ADS)

Xu, Bo; Ma, Wen; Wu, Xiao; Qian, Lijun; Jiang, Shan

2018-04-01

Intumescent flame retardant (IFR) EVA composites were prepared based on a hyperbranched triazine charring-foaming agent (HTCFA) and ammonium polyphosphate (APP). The synergistic effect of HTCFA and APP on the flame retardancy and thermal behavior of the composites were investigated through flammability tests, cone calorimeter measurements, thermogravimetric analysis (TGA) including evolved gas analysis (TG-IR) and residue analysis (Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS), x-ray Photoelectron Spectroscopy (XPS) and scanning electron microscopy (SEM)). The flammability test results showed HTCFA/APP (1/3) system presented the best synergistic effect in flame-retardant EVA composites with the highest LOI value and UL-94 V-0 rating. As for cone calorimeter results, IFR changed the combustion behavior of EVA and resulted in remarkable decrease of flammability and smoke product. TGA results showed the synergistic effect between APP and HTCFA could strengthen the char-forming ability of composites. TG-IR results indicated the melt viscosities and gas release with increasing temperature were well-correlated for EVA/IFR composite. The residue analysis results from SEM, LRS, FT-IR and XPS revealed IFR promoted forming more compact graphitic char layer, connected by rich P–O–C and P–N structures.

EVA Skills training in the NBL

NASA Image and Video Library

2012-11-27

ESA astronaut and first astronaut from the United Kingdom, Timothy Peake, with NASA astronaut Scott Tingle (unassigned) during EVA Skills training in the NBL. Photo Date: November 27, 2012. Location: NBL - Pool Topside. Photographer: Robert Markowitz

Baseline tests of the EVA change-of-pace coupe electric passenger vehicle

NASA Technical Reports Server (NTRS)

Bozek, J. M.; Maslowski, E. A.; Dustin, M. O.

1977-01-01

The EVA Change-of-Pace Coupe, is an electric passenger vehicle, to characterize the state-of-the-art of electric vehicles. The EVA Change-of-Pace Coupe is a four passenger sedan that has been coverted to an electric vehicle. It is powered by twenty 6 volt traction batteries through a silicon controlled rectifier chopper controller actuated by a foot throttle to change the voltage applied to the series wound, direct current motor. Braking is accomplished with a vacuum assist hydraulic braking system. Regenerative braking is also provided.

Astronaut Dale Gardner holds up for sale sign after EVA

NASA Image and Video Library

1984-11-14

51A-104-049 (14 Nov. 1984) --- Astronaut Dale A. Gardner, having just completed the major portion of his second extravehicular activity (EVA) period in three days aboard the Earth-orbiting Discovery, holds up a for sale sign. Astronaut Joseph P. Allen IV, who also participated in the two EVA, is reflected in Gardner's helmet visor. A portion of each of two recovered satellites is in lower right corner, with Westar nearer Discovery's aft. Dr. Allen, standing on the mobile foot restraint, connected to the remote manipulator system. Photo credit: NASA

Perrin smiles through the visor of his EVA helmet while working beside the MBS during STS-111 EVA 2

NASA Image and Video Library

2002-06-11

STS111-307-017 (11 June 2002) --- Astronaut Philippe Perrin, STS-111 mission specialist representing CNES, the French Space Agency, participates in the second scheduled session of extravehicular activity (EVA) for the STS-111 mission. During the spacewalk, Perrin and Chang-Diaz attached power, data and video cables from the International Space Station (ISS) to the Mobile Base System (MBS) and used a power wrench to complete the attachment of the MBS onto the Mobile Transporter (MT).

STS-69 Flight Day 10 Highlights

NASA Technical Reports Server (NTRS)

1995-01-01

In honor of the Extravehicular Activity (EVA) spacewalk today, the tenth day of the STS-69 mission, the astronauts, Cmdr. Dave Walker, Pilot Ken Cockrell, and Mission Specialists Jim Voss, Jim Newman, and Mike Gernhardt, were awakened to the Frankie Valle and the Four Seasons tune, 'Walk Like A Man.' Voss and Gernhardt tested the new thermal spacesuits and some new tools in the shuttle's cargo bay for six hours. The EVA was successful. The rest of the astronauts monitored the EVA and packed up the equipment and experiments in preparation for their reentry flight tomorrow.

EVA Roadmap: New Space Suit for the 21st Century

NASA Technical Reports Server (NTRS)

Yowell, Robert

1998-01-01

New spacesuit design considerations for the extra vehicular activity (EVA) of a manned Martian exploration mission are discussed. Considerations of the design includes:(1) regenerable CO2 removal, (2) a portable life support system (PLSS) which would include cryogenic oxygen produced from in-situ manufacture, (3) a power supply for the EVA, (4) the thermal control systems, (5) systems engineering, (5) space suit systems (materials, and mobility), (6) human considerations, such as improved biomedical sensors and astronaut comfort, (7) displays and controls, and robotic interfaces, such as rovers, and telerobotic commands.

EVA view taken during STS-102

NASA Image and Video Library

2001-03-11

STS102-312-004 (11 March 2001) --- Astronaut James S. Voss works while anchored to the remote manipulator system (RMS) robot arm on the Space Shuttle Discovery. This extravehicular activity (EVA), on which Voss was joined by astronaut Susan J. Helms (out of frame), was the first of two scheduled STS-102 space walks. The pair, destined to become members of the Expedition Two crew aboard the station later in the mission, rode aboard Discovery into orbit and at the time of this EVA were still regarded as STS-102 mission specialists.

An innovative exercise method to simulate orbital EVA work - Applications to PLSS automatic controls

NASA Technical Reports Server (NTRS)

Lantz, Renee; Vykukal, H.; Webbon, Bruce

1987-01-01

An exercise method has been proposed which may satisfy the current need for a laboratory simulation representative of muscular, cardiovascular, respiratory, and thermoregulatory responses to work during orbital extravehicular activity (EVA). The simulation incorporates arm crank ergometry with a unique body support mechanism that allows all body position stabilization forces to be reacted at the feet. By instituting this exercise method in laboratory experimentation, an advanced portable life support system (PLSS) thermoregulatory control system can be designed to more accurately reflect the specific work requirements of orbital EVA.

Astronaut Musgrave performing EVA during STS-6

NASA Technical Reports Server (NTRS)

1983-01-01

Views of Mission Specialist F. Story Musgrave performing an extravehicular activity (EVA) during the STS-6 mission. In this view, Musgrave uses hand holds in the payload bay door hinge line to move towards the aft payload bay (30215); Musgrave conducts a simulation of a contingency EVA in the aft payload bay. This was designed to return the inertial upper stage (IUS) support equipment's tilt table device to its normal stowed configuration in the event of failure of an automatic system. A cloud-covered earth can be seen in the background (30216).

Severe paediatric conditions linked with EV-A71 and EV-D68, France, May to October 2016

PubMed Central

Antona, Denise; Kossorotoff, Manoëlle; Schuffenecker, Isabelle; Mirand, Audrey; Leruez-Ville, Marianne; Bassi, Clément; Aubart, Mélodie; Moulin, Florence; Lévy-Bruhl, Daniel; Henquell, Cécile; Lina, Bruno; Desguerre, Isabelle

2016-01-01

We report 59 cases of severe paediatric conditions linked with enterovirus (EV)-A71 and EV-D68 in France between May and October 2016. Fifty-two children had severe neurological symptoms. EV sequence-based typing for 42 cases revealed EV-A71 in 21 (18 subgenotype C1, detected for the first time in France) and EV-D68 in eight. Clinicians should be encouraged to obtain stool and respiratory specimens from patients presenting with severe neurological disorders for EV detection and characterisation. PMID:27918268

A primer on EVA for health care providers.

PubMed

Grant, James L

2007-01-01

Unlike accounting earnings, economic profit (EVA) is a measure of a company's true earnings because it fully "accounts" for the costs of all forms of financing, including debt and equity. In the EVA view, a company is not truly profitable unless it earns a return on capital that bests the opportunity cost of capital. That being said, the question addressed here is how to measure the economic profit of providers in the health care sector, which is largely comprised of not-for-profit organizations such as clinics, laboratories, and hospitals.

Shift of Enterovirus species among children in Cameroon--identification of a new enterovirus, EV-A119.

PubMed

Ayukekbong, James; Kabayiza, Jean-Claude; Lindh, Magnus; Nkuo-Akenji, Theresia; Tah, Ferdinand; Bergström, Tomas; Norder, Helene

2013-09-01

Infections caused by human enteroviruses (EVs) are often asymptomatic or mild, although they may cause more severe illnesses as meningitis and acute flaccid paralysis. EVs have globally posed a threat to children, and outbreaks of aseptic meningitis and hand, foot and mouth disease are frequently reported. To identify EV strains circulating among healthy children in a small community in Limbe, Cameroon two years apart. Species and EV types were obtained by partial 5'UTR-VP4 and VP1 sequencing of RNA from stool samples collected in October 2009 and September 2011 from 150 children in Cameroon. In all, 74 children (49%) were infected with 28 different types of EV. There were 29 (54%) infected children in 2009, and 45 (47%) in 2011. There was a significant difference between detected species of EV, with 15 (47%) children infected with EV-A in 2009, and 22 (71%) with EV-B in 2011 (p=0.0001). In 2009, one child was infected by a divergent EV, which was most similar to EV-A90. Based on the complete VP1 sequence, it was shown to be a new EV designated EV-A119. The current study shows a high heterogeneity of circulating EV types among children in Limbe, Cameroon, and a previously not described shift in predominating EV species. Copyright © 2013 Elsevier B.V. All rights reserved.

Human Research Program Human Health Countermeasures Element Extravehicular Activity (EVA) Risk Standing Review Panel (SRP)

NASA Technical Reports Server (NTRS)

Norfleet, William; Harris, Bernard

2009-01-01

The Extravehicular Activity (EVA) Risk Standing Review Panel (SRP) was favorably impressed by the operational risk management approach taken by the Human Research Program (HRP) Integrated Research Plan (IRP) to address the stated life sciences issues. The life sciences community at the Johnson Space Center (JSC) seems to be focused on operational risk management. This approach is more likely to provide risk managers with the information they need at the time they need it. Concerning the information provided to the SRP by the EVA Physiology, Systems, and Performance Project (EPSP), it is obvious that a great deal of productive activity is under way. Evaluation of this information was hampered by the fact that it often was not organized in a fashion that reflects the "Gaps and Tasks" approach of the overall Human Health Countermeasures (HHC) effort, and that a substantial proportion of the briefing concerned subjects that, while interesting, are not part of the HHC Element (e.g., the pressurized rover presentation). Additionally, no information was provided on several of the tasks or how they related to work underway or already accomplished. This situation left the SRP having to guess at the efforts and relationship to other elements, and made it hard to easily map the EVA Project efforts currently underway, and the data collected thus far, to the gaps and tasks in the IRP. It seems that integration of the EPSP project into the HHC Element could be improved. Along these lines, we were concerned that our SRP was split off from the other participating SRPs at an early stage in the overall agenda for the meeting. In reality, the concerns of EPSP and other projects share much common ground. For example, the commonality of the concerns of the EVA and exercise physiology groups is obvious, both in terms of what reduced exercise capacity can do to EVA capability, and how the exercise performed during an EVA could contribute to an overall exercise countermeasure prescription.

An extravehicular suit impact load attenuation study to improve astronaut bone fracture prediction.

PubMed

Sulkowski, Christina M; Gilkey, Kelly M; Lewandowski, Beth E; Samorezov, Sergey; Myers, Jerry G

2011-04-01

Understanding the contributions to the risk of bone fracture during spaceflight is essential for mission success. A pressurized extravehicular activity (EVA) suit analogue test bed was developed, impact load attenuation data were obtained, and the load at the hip of an astronaut who falls to the side during an EVA was characterized. Offset (representing the gap between the EVA suit and the astronaut's body), impact load magnitude, and EVA suit operating pressure were factors varied in the study. The attenuation data were incorporated into a probabilistic model of bone fracture risk during spaceflight, replacing the previous load attenuation value that was based on commercial hip protector data. Load attenuation was more dependent on offset than on pressurization or load magnitude, especially at small offset values. Load attenuation factors for offsets between 0.1-1.5 cm were 0.69 +/- 0.15, 0.49 +/- 0.22, and 0.35 +/- 0.18 for mean impact forces of 4827, 6400, and 8467 N, respectively. Load attenuation factors for offsets of 2.8-5.3 cm were 0.93 +/- 0.2, 0.94 +/- 0.1, and 0.84 +/- 0.5 for the same mean impact forces. The mean and 95th percentile bone fracture risk index predictions were each reduced by 65-83%. The mean and 95th percentile bone fracture probability predictions were both reduced approximately 20-50%. The reduction in uncertainty and improved confidence in bone fracture predictions increased the fidelity and credibility of the fracture risk model and its benefit to mission design and in-flight operational decisions.

A Simultaneous Analytical Method for Duplex Identification of Porcine and Horse in the Meat Products by EvaGreen based Real-time PCR.

PubMed

Sakalar, Ergün; Ergün, Seyma Özçirak; Akar, Emine

2015-01-01

A duplex real-time polymerase chain reaction (PCR) based assay for the detection of porcine and horse meat in sausages was designed by using EvaGreen fluorescent dye. Primers were selected from mitochondrial 12S rRNA and 16S rRNA genes which are powerful regions for identification of horse and porcine meat. DNA from reference samples and industrial products was successfully extracted using the GIDAGEN® Multi-Fast DNA Isolation Kit. Genomes were identified based on their specific melting peaks (Mp) which are 82.5℃ and 78℃ for horse and porcine, respectively. The assay used in this study allowed the detection of as little as 0.0001% level of horse meat and 0.001% level of porcine meat in the experimental admixtures. These findings indicate that EvaGreen based duplex real-time PCR is a potentially sensitive, reliable, rapid and accurate assay for the detection of meat species adulterated with porcine and horse meats.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.; Glick, S.H.

We have conducted a series of accelerated exposure test (AET) studies for various crystalline-Si (c-Si) and amorphous-Si (a-Si) cell samples that were encapsulated with different superstrates, pottants, and substrates. Nonuniform browning patterns of ethylene vinyl acetate (EVA) pottants were observed for glass/EVA/glass-encapsulated c-Si cell samples under solar simulator exposures at elevated temperatures. The polymer/polymer-configured laminates with Tedlar or Tefzel did not discolor because of photobleaching reactions, but yellowed with polyester or nylon top films. Delamination was observed for the polyester/EVE layers on a-Si minimodules and for a polyolefin-based thermoplastic pottant at high temperatures. For all tested c-Si cell samples, irregularmore » changes in the current-voltage parameters were observed that could not be accounted for simply by the transmittance changes of the superstrate/pottant layers. Silicone-type adhesives used under UV-transmitting polymer top films were observed to cause greater cell current/efficiency loss than EVA or polyethylene pottants. {copyright} {ital 1999 American Institute of Physics.}« less

Task network models in the prediction of workload imposed by extravehicular activities during the Hubble Space Telescope servicing mission

NASA Technical Reports Server (NTRS)

Diaz, Manuel F.; Takamoto, Neal; Woolford, Barbara

1994-01-01

In a joint effort with Brooks AFB, Texas, the Flight Crew Support Division at JSC has begun a computer simulation and performance modeling program directed at establishing the predictive validity of software tools for modeling human performance during spaceflight. This paper addresses the utility of task network modeling for predicting the workload that astronauts are likely to encounter in extravehicular activities (EVA) during the Hubble Space Telescope (HST) repair mission. The intent of the study was to determine whether two EVA crewmembers and one intravehicular activity (IVA) crewmember could reasonably be expected to complete HST Wide Field/Planetary Camera (WFPC) replacement in the allotted time. Ultimately, examination of the points during HST servicing that may result in excessive workload will lead to recommendations to the HST Flight Systems and Servicing Project concerning (1) expectation of degraded performance, (2) the need to change task allocation across crewmembers, (3) the need to expand the timeline, and (4) the need to increase the number of EVA's.

Russian EVA 39

NASA Image and Video Library

2014-08-18

ISS040E099874 (08/18/2014) --- Cosmonauts Alexander Skvortsov (red stripe - foreground) and Oleg Artemyev (blue stripe - background), Expedition 40 flight engineers, move to the Russian Service Module for repairs during International Space Station Russian EVA 39 on Aug. 18, 2014.

Russian EVA 39.

NASA Image and Video Library

2014-08-18

ISS040E099104 (08/18/2014) --- View of Cosmonaut Oleg Artemyev (blue stripe), Expedition 40 flight engineer outside the International Space Station, taken while performing maintenance work on the Russian segment during the Russian EVA 39 on Aug 18 2014.

View of Mission Control during lunar surface Apollo 11 EVA

NASA Image and Video Library

1969-07-20

Overall view of the Mission Operations Control Room in the Mission Control Center, bldg 30, during the lunar surface extravehicular activity (EVA) of Apollo 11 Astronauts Neil A. Armstrong and Edwin E. Aldrin Jr.

EASE (Experimental Assembly of Structures in EVA) overview of selected results

NASA Technical Reports Server (NTRS)

Akin, David L.

1987-01-01

Experimental Assembly of Structures in EVA (EASE) objectives, experimental protocol, neutral buoyancy simulation, task time distribution, assembly task performance, metabolic rate/biomedical readouts are summarized. This presentation is shown in charts, figures, and graphs.

Astronaut Dale Gardner rehearses control of MMU during EVA practice

NASA Technical Reports Server (NTRS)

1984-01-01

Astronaut Dale A. Gardner, 51-A mission specialist, rehearses control of manned maneuvering unit (MMU) during a practice for an extravehicular activity (EVA). Gardner is in the Shuttle mockup and integration laboratory at JSC.

Guiding principle for crystalline Si photovoltaic modules with high tolerance to acetic acid

NASA Astrophysics Data System (ADS)

Masuda, Atsushi; Hara, Yukiko

2018-04-01

A guiding principle for highly reliable crystalline Si photovoltaic modules, especially those with high tolerance to acetic acid generated by hydrolysis reaction between water vapor and an ethylene-vinyl acetate (EVA) encapsulant, is proposed. Degradation behavior evaluated by the damp heat test strongly depends on Ag finger electrodes and also EVA encapsulants. The acetic acid concentration in EVA on the glass side directly determines the degradation behavior. The most important factor for high tolerance is the type of Ag finger electrode materials when using an EVA encapsulant. Photovoltaic modules using newly developed crystalline Si cells with improved Ag finger electrode materials keep their maximum power of 80% of the initial value even after the damp heat test at 85 °C and 85% relative humidity for 10000 h. The pattern of dark regions in electroluminescence images is also discussed on the basis of the dynamics of acetic acid in the modules.

Use of the Remote Access Virtual Environment Network (RAVEN) for coordinated IVA-EVA astronaut training and evaluation.

PubMed

Cater, J P; Huffman, S D

1995-01-01

This paper presents a unique virtual reality training and assessment tool developed under a NASA grant, "Research in Human Factors Aspects of Enhanced Virtual Environments for Extravehicular Activity (EVA) Training and Simulation." The Remote Access Virtual Environment Network (RAVEN) was created to train and evaluate the verbal, mental and physical coordination required between the intravehicular (IVA) astronaut operating the Remote Manipulator System (RMS) arm and the EVA astronaut standing in foot restraints on the end of the RMS. The RAVEN system currently allows the EVA astronaut to approach the Hubble Space Telescope (HST) under control of the IVA astronaut and grasp, remove, and replace the Wide Field Planetary Camera drawer from its location in the HST. Two viewpoints, one stereoscopic and one monoscopic, were created all linked by Ethernet, that provided the two trainees with the appropriate training environments.

Design and simulation of EVA tools for first servicing mission of HST

NASA Technical Reports Server (NTRS)

Naik, Dipak; Dehoff, P. H.

1993-01-01

The Hubble Space Telescope (HST) was launched into near-earth orbit by the space shuttle Discovery on April 24, 1990. The payload of two cameras, two spectrographs, and a high-speed photometer is supplemented by three fine-guidance sensors that can be used for astronomy as well as for star tracking. A widely reported spherical aberration in the primary mirror causes HST to produce images of much lower quality than intended. A space shuttle repair mission in late 1993 will install small corrective mirrors that will restore the full intended optical capability of the HST. The first servicing mission (FSM) will involve considerable extravehicular activity (EVA). It is proposed to design special EVA tools for the FSM. This report includes details of the data acquisition system being developed to test the performance of the various EVA tools in ambient as well as simulated space environment.

Investigation of the effects of extravehicular activity (EVA) gloves on performance

NASA Technical Reports Server (NTRS)

Bishu, Ram R.; Klute, Glenn

1993-01-01

The objective was to assess the effects of extravehicular activity (EVA) gloves at different pressures on human hand capabilities. A factorial experiment was performed in which three types of EVA gloves were tested at five pressure differentials. The independent variables tested in this experiment were gender, glove type, pressure differential, and glove make. Six subjects participated in an experiment where a number of dexterity measures, namely time to tie a rope, and the time to assemble a nut and bolt were recorded. Tactility was measured through a two point discrimination test. The results indicate that with EVA gloves strength is reduced by nearly 50 percent, there is a considerable reduction in dexterity, performance decrements increase with increasing pressure differential, and some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand. The implications for the designer are discussed.

High Performance EVA Glove Collaboration: Glove Injury Data Mining Effort

NASA Technical Reports Server (NTRS)

Reid, C. R.; Benosn, E.; England, S.; Norcross, J. R.; McFarland, S. M.; Rajulu, S.

2014-01-01

Human hands play a significant role during extravehicular activity (EVA) missions and Neutral Buoyancy Lab (NBL) training events, as they are needed for translating and performing tasks in the weightless environment. It is because of this high frequency usage that hand- and arm-related injuries and discomfort are known to occur during training in the NBL and while conducting EVAs. Hand-related injuries and discomforts have been occurring to crewmembers since the days of Apollo. While there have been numerous engineering changes to the glove design, hand-related issues still persist. The primary objectives of this study are therefore to: 1) document all known EVA glove-related injuries and the circumstances of these incidents, 2) determine likely risk factors, and 3) recommend ergonomic mitigations or design strategies that can be implemented in the current and future glove designs. METHODS: The investigator team conducted an initial set of literature reviews, data mining of Lifetime Surveillance of Astronaut Health (LSAH) databases, and data distribution analyses to understand the ergonomic issues related to glove-related injuries and discomforts. The investigation focused on the injuries and discomforts of U.S. crewmembers who had worn pressurized suits and experienced glove-related incidents during the 1980 to 2010 time frame, either during training or on-orbit EVA. In addition to data mining of the LSAH database, the other objective of the study was to find complimentary sources of information such as training experience, EVA experience, suit-related sizing data, and hand-arm anthropometric data to be tied to the injury data from LSAH. RESULTS: Past studies indicated that the hand was the most frequently injured part of the body during both EVA and NBL training. This study effort thus focused primarily on crew training data in the NBL between 2002 and 2010. Of the 87 recorded training incidents, 19 occurred to women and 68 to men. While crew ages ranged from thirties to fifties, the age category most affected was in the forties range. Incident rate calculations (incidents per 100 training runs) revealed that the 2002, 2003, and 2004 time periods registered the highest reported incident rate levels (3.4, 6.1, and 4.1 respectively) when compared to the following years (all = 1.0). In addition to general hand-arm discomfort being the highest reported result from training, specific types of hand injuries or symptoms included erythema, fingernail delamination, abrasions, muscle soreness/fatigue, paresthesia, bruising, blanching, and edema. Specific body locations most affected by hand injuries included the metacarpophalangeal joints, fingernails, finger crotches, fingers in general, interphalangeal joints, and fingertips. Causes of injuries reported in the LSAH data were primarily attributed to the forces that the gloved hands were exposed to due to hand intensive tasks and/or poor glove sizing. DISCUSSION: Although the age data indicate that most injuries are reported by male crewmembers in their forties, that is also the dominant gender and age range of most EVA crew therefore it is not an unexpected finding. Age and gender analysis will continue as more details on the uninjured population is accrued. While there is a reasonable mechanism to link training quantity to injury, the results were inconsistent and point to the need for a consistent method of suit-related injury screening and documentation. For instance, the high-incident rate levels for the years 2002 to 2004 could be attributed to a comprehensive medical review of crewmembers post-NBL EVA training that occurred from July 19, 2002 to January 16, 2004. Furthermore, there could have been increased awareness from an investigation at the NBL. These investigations may have temporarily increased the fidelity of reported injuries and discomforts during these dates as compared to surrounding years, when injury signs and symptom were no longer actively being investigated but rather voluntarily reported. Data mining for possible mechanistic factors continues and includes more detailed training timelines, hand anthropometry, and suit sizing information. The limited published data looking at hand-arm anthropometry correlated hand-anthropometry metrics with injuries stemming from glove design and operation. Future work will include further evaluation of body sizing and fit in relation to hand injury incidents.

Mars Surface Tunnel Element Concept

NASA Technical Reports Server (NTRS)

Rucker, Michelle A.

2016-01-01

How crews get into or out of their ascent vehicle has profound implications for Mars surface architecture. Extravehicular Activity (EVA) hatches and Airlocks have the benefit of relatively low mass and high Technology Readiness Level (TRL), but waste consumables with a volume depressurization for every ingress/egress. Perhaps the biggest drawback to EVA hatches or Airlocks is that they make it difficult to keep Martian dust from being tracked back into the ascent vehicle, in violation of planetary protection protocols. Suit ports offer the promise of dust mitigation by keeping dusty suits outside the cabin, but require significant cabin real estate, are relatively high mass, and current operational concepts still require an EVA hatch to get the suits outside for the first EVA, and back inside after the final EVA. This is primarily because current designs don't provide enough structural support to protect the suits from ascent/descent loads or potential thruster plume impingement. For architectures involving more than one surface element-such as an ascent vehicle and a rover or surface habitat-a retractable tunnel is an attractive option. By pushing spacesuit don/doff and EVA operations to an element that remains on the surface, ascended vehicle mass and dust can be minimized. What's more, retractable tunnels provide operational flexibility by allowing surface assets to be re-configured or built up over time. Retractable tunnel functional requirements and design concepts being developed as part of the National Aeronautics and Space Administration's (NASA) Evolvable Mars Campaign (EMC) work will add a new ingress/egress option to the surface architecture trade space.

First flight test results of the Simplified Aid For EVA Rescue (SAFER) propulsion unit

NASA Technical Reports Server (NTRS)

Meade, Carl J.

1995-01-01

The Simplified Aid for EVA Rescue (SAFER) is a small, self-contained, propulsive-backpack system that provides free-flying mobility for an astronaut engaged in a space walk, also known as extravehicular activity (EVA.) SAFER contains no redundant systems and is intended for contingency use only. In essence, it is a small, simplified version of the Manned Maneuvering Unit (MMU) last flown aboard the Space Shuttle in 1985. The operational SAFER unit will only be used to return an adrift EVA astronaut to the spacecraft. Currently, if an EVA crew member inadvertently becomes separated from the Space Shuttle, the Orbiter will maneuver to within the crew member's reach envelope, allowing the astronaut to regain contact with the Orbiter. However, with the advent of operations aboard the Russian MIR Space Station and the International Space Station, the Space Shuttle will not be available to effect a timely rescue. Under these conditions, a SAFER unit would be worn by each EVA crew member. Flight test of the pre-production model of SAFER occurred in September 1994. The crew of Space Shuttle Mission STS-64 flew a 6.9 hour test flight which included performance, flying qualities, systems, and operational utility evaluations. We found that the unit offers adequate propellant and control authority to stabilize and enable the return of a tumbling/separating crew member. With certain modifications, production model of SAFER can provide self-rescue capability to a separated crew member. This paper will present the program background, explain the flight test results and provide some insight into the complex operations of flight test in space.

Hyperoxia Inhibits T Cell Activation in Mice

NASA Astrophysics Data System (ADS)

Hughes-Fulford, M.; Meissler, J.; Aguayo, E. T.; Globus, R.; Aguado, J.; Candelario, T.

2013-02-01

Background: The immune response is blunted in mice and humans in spaceflight. The effects of hyperoxia in mice alter expression of some of the same immune response genes. If these two conditions are additive, there could be an increased risk of infection in long duration missions. Immunosuppression is seen in healthy astronauts who have flown in space; however little is known about the mechanisms that cause the reduced immunity in spaceflight. Here we examine the role of oxidative stress on mice exposed to periods of high O2 levels mimicking pre-breathing protocols and extravehicular activity (EVA). To prevent decompression sickness, astronauts are exposed to elevated oxygen (hyperoxia) before and during EVA activities. Spaceflight missions may entail up to 24 hours of EVA per crewmember per week to perform construction and maintenance tasks. The effectiveness and success of these missions depends on designing EVA systems and protocols that maximize human performance and efficiency while minimizing health and safety risks for crewmembers. To our knowledge, no studies have been conducted on the immune system under 100% oxygen exposures to determine the potential for immune compromise due to prolonged and repeated EVAs. Methods: Animals were exposed to hyperoxic or control conditions for 8 hours per day over a period of 3 days, initiated 4 hours into the dark cycle (12h dark/12h light), using animal environmental control cabinets and oxygen controller (Biospherix, Lacona, NY). Experimental mice were exposed to 98-100% oxygen as a model for pre-breathing and EVA conditions, while control mice were maintained in chambers supplied with compressed air. These are ground control studies where we use real-time RTPCR (qRTPCR) to measure gene expression of the early immune gene expression during bead activation of splenocytes of normoxic and hyperoxic mice. All procedures were reviewed and approved by the IACUC at Ames Research Center. After the last 8h of hyperoxic exposure, spleens were removed and the splenocytes were isolated and kept as individual biological samples. We have also examined transcription factors (JASPAR) and pathways of the immune system to help us understand the mechanism of regulation. Results: Our recent mouse immunology experiment aboard STS-131 suggests that the early T cell immune response was inhibited in animals that have been exposed to spaceflight, even 24 hours after return to earth. Moreover, recent experiments in hyperoxic mice show that many of the same genes involved in early T cell activation were altered. Specifically, expression of IL-2Rα, Cxcl2, TNFα, FGF2, LTA and BCL2 genes are dysregulated in mice exposed to hyperoxia. Conclusions: If these hyperoxia-induced changes of gene expression in early T cell activation are additive to the changes seen in the microgravity of spaceflight, there could be an increased infection risk to EVA astronauts, which should be addressed prior to conducting a Mars or other long-term mission.

A synopsis of the EVA training conducted on EASE/ACCESS for STS-61-B

NASA Technical Reports Server (NTRS)

Havens, Kathryn A.

1987-01-01

Experimental Assembly of Structure in EVA (EASE)/Assembly Concept for Construction of Erectable Space Structures (ACCESS) training problems; photography/television coverage; training schedules; flight data file (FDF), and flight rules production are summarized.

EVA Physiology, Systems and Performance [EPSP] Project

NASA Technical Reports Server (NTRS)

Gernhardt, Michael L.

2010-01-01

This viewgraph presentation gives a general overview of the biomedical and technological challenges of Extravehicular Activity (EVA). The topics covered include: 1) Prebreathe Protocols; 2) Lunar Suit Testing and Development; and 3) Lunar Electric Rover and Exploration Operations Concepts.

STS-133 crew members Drew, Kopra and Stott during EVA Tile Repair.

NASA Image and Video Library

2010-03-30

JSC2010-E-044337 (30 March 2010) --- NASA astronaut Tim Kopra, STS-133 mission specialist, participates in an EVA tile repair training session in the Space Vehicle Mockup Facility at NASA's Johnson Space Center.

Wavelet-based multiscale window transform and energy and vorticity analysis

NASA Astrophysics Data System (ADS)

Liang, Xiang San

A new methodology, Multiscale Energy and Vorticity Analysis (MS-EVA), is developed to investigate sub-mesoscale, meso-scale, and large-scale dynamical interactions in geophysical fluid flows which are intermittent in space and time. The development begins with the construction of a wavelet-based functional analysis tool, the multiscale window transform (MWT), which is local, orthonormal, self-similar, and windowed on scale. The MWT is first built over the real line then modified onto a finite domain. Properties are explored, the most important one being the property of marginalization which brings together a quadratic quantity in physical space with its phase space representation. Based on MWT the MS-EVA is developed. Energy and enstrophy equations for the large-, meso-, and sub-meso-scale windows are derived and their terms interpreted. The processes thus represented are classified into four categories: transport; transfer, conversion, and dissipation/diffusion. The separation of transport from transfer is made possible with the introduction of the concept of perfect transfer. By the property of marginalization, the classical energetic analysis proves to be a particular case of the MS-EVA. The MS-EVA developed is validated with classical instability problems. The validation is carried out through two steps. First, it is established that the barotropic and baroclinic instabilities are indicated by the spatial averages of certain transfer term interaction analyses. Then calculations of these indicators are made with an Eady model and a Kuo model. The results agree precisely with what is expected from their analytical solutions, and the energetics reproduced reveal a consistent and important aspect of the unknown dynamic structures of instability processes. As an application, the MS-EVA is used to investigate the Iceland-Faeroe frontal (IFF) variability. A MS-EVA-ready dataset is first generated, through a forecasting study with the Harvard Ocean Prediction System using the data gathered during the 1993 NRV Alliance cruise. The application starts with a determination of the scale window bounds, which characterize a double-peak structure in either the time wavelet spectrum or the space wavelet spectrum. The resulting energetics, when locally averaged, reveal that there is a clear baroclinic instability happening around the cold tongue intrusion observed in the forecast. Moreover, an interaction analysis shows that the energy released by the instability indeed goes to the meso-scale window and fuel the growth of the intrusion. The sensitivity study shows that, in this case, the key to a successful application is a correct decomposition of the large-scale window from the meso-scale window.

Impact of embedded voids on thin-films with high thermal expansion coefficients mismatch

NASA Astrophysics Data System (ADS)

Khafagy, Khaled H.; Hatem, Tarek M.; Bedair, Salah M.

2018-01-01

Using technology to reduce defects at heterogeneous interfaces of thin-films is at a high-priority for modern semiconductors. The current work utilizes a three-dimensional multiple-slip crystal-plasticity model and specialized finite-element formulations to study the impact of the embedded void approach (EVA) to reduce defects in thin-films deposited on a substrate with a highly mismatched thermal expansion coefficient, in particular, the growth of an InGaN thin-film on a Si substrate, where EVA has shown a remarkable reduction in stresses on the side of the embedded voids.

Mission control activity during STS-61 EVA-1

NASA Image and Video Library

1993-12-05

Joseph Fanelli, at the Integrated Communications Officer console, monitors the televised activity of Astronauts Story Musgrave and Jeffrey A. Hoffman. The vetern astronauts were performing the first extravehicular activity (EVA-1) of the STS-61 Hubble Space Telescope (HST) servicing mission.

Wilson at RWS for STS-131 EVA 3 SSRMS Support

NASA Image and Video Library

2010-04-13

View of Stephanie Wilson as she works at the Robotics Workstation (RWS) in US Laboratory Destiny as she conducts a Space Station Remote Manipulator System (SSRMS) Ammonia Tank Assembly (ATA) retrieval in support of STS-131 EVA 3.

STS-335 crew training, EVA TPS Overview with instructor John Ray

NASA Image and Video Library

2010-11-03

PHOTO DATE: 11-03-10 LOCATION: Bldg. 9NW - TPST Training Area SUBJECT: STS-335 crew training, EVA TPS Overview with instructor John Ray WORK ORDER: 03247-BS__STS335TILEREPAIR_11-03-10 PHOTOGRAPHER: BILL STAFFORD

Astronauts Allen and Gemar during extravehicular activity (EVA) training in CCT

NASA Technical Reports Server (NTRS)

1994-01-01

Astronauts Charles D. (Sam) Gemar, and Andrew M. Allen participate in a training exercise at JSC's Crew Compartment Trainer (CCT), located in the Space Vehicle Mockup Facility. Gemar sits inside the airlock as Allen reviews procedures for EVA.

Skylab Astronaut participates in EVA to deploy twin pole solar shield

NASA Image and Video Library

1973-08-06

SL3-118-2182 (6 Aug. 1973) --- Skylab 3 astronaut participates in the Aug. 6, 1973 extravehicular activity (EVA) during which the twin pole solar shield was deployed to help shade the Orbital Workshop (OWS). Photo credit: NASA

Tile survey seen during EVA 3

NASA Image and Video Library

2005-08-03

S114-E-6412 (3 August 2005) --- Space Shuttle Discovery’s underside thermal protection tiles are featured in this image photographed by astronaut Stephen K. Robinson, STS-114 mission specialist, during the mission’s third session of extravehicular activities (EVA).

7. LESLIE WICKMAN, EVA (EXTRA VEHICULAR ACTIVITIES) SPECIALIST, IN SPACE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. LESLIE WICKMAN, EVA (EXTRA VEHICULAR ACTIVITIES) SPECIALIST, IN SPACE SUIT AFTER TESTING IN NEUTRAL BUOYANCY TANK. AVERAGE COST OF SUIT IS $1,000,000. - Marshall Space Flight Center, Neutral Buoyancy Simulator Facility, Rideout Road, Huntsville, Madison County, AL

Development of a Pre-Prototype Power Assisted Glove End Effector for Extravehicular Activity

NASA Technical Reports Server (NTRS)

1986-01-01

The purpose of this program was to develop an EVA power tool which is capable of performing a variety of functions while at the same time increasing the EVA crewmember's effectiveness by reducing hand fatigue associated with gripping tools through a pressurized EMU glove. The Power Assisted Glove End Effector (PAGE) preprototype hardware met or exceeded all of its technical requirements and has incorporated acoustic feedback to allow the EVA crewmember to monitor motor loading and speed. If this tool is to be developed for flight use, several issues need to be addressed. These issues are listed.

Severe paediatric conditions linked with EV-A71 and EV-D68, France, May to October 2016.

PubMed

Antona, Denise; Kossorotoff, Manoëlle; Schuffenecker, Isabelle; Mirand, Audrey; Leruez-Ville, Marianne; Bassi, Clément; Aubart, Mélodie; Moulin, Florence; Lévy-Bruhl, Daniel; Henquell, Cécile; Lina, Bruno; Desguerre, Isabelle

2016-11-17

We report 59 cases of severe paediatric conditions linked with enterovirus (EV)-A71 and EV-D68 in France between May and October 2016. Fifty-two children had severe neurological symptoms. EV sequence-based typing for 42 cases revealed EV-A71 in 21 (18 subgenotype C1, detected for the first time in France) and EV-D68 in eight. Clinicians should be encouraged to obtain stool and respiratory specimens from patients presenting with severe neurological disorders for EV detection and characterisation. This article is copyright of The Authors, 2016.

STS-112 Crew Interviews: Melroy

NASA Technical Reports Server (NTRS)

2002-01-01

Pamela A. Melroy USAF Pilot, is seen during a prelaunch interview. She gives a brief overview of the STS-112 mission which is to install the S1 truss on the International Space Station. She also gives some specific details about the structural design of the S1 truss. Pamela Melroy is also the Internal EVA (IV) coordinator for this mission. She talks about her responsibilities as the IV which are to direct the spacewalkers back into the Airlock after the S1 is installed. A detailed description about the goals of EVA (2) and EVA (3) are also given by Melroy.

EVA Glove Research Team

NASA Technical Reports Server (NTRS)

Strauss, Alvin M.; Peterson, Steven W.; Main, John A.; Dickenson, Rueben D.; Shields, Bobby L.; Lorenz, Christine H.

1992-01-01

The goal of the basic research portion of the extravehicular activity (EVA) glove research program is to gain a greater understanding of the kinematics of the hand, the characteristics of the pressurized EVA glove, and the interaction of the two. Examination of the literature showed that there existed no acceptable, non-invasive method of obtaining accurate biomechanical data on the hand. For this reason a project was initiated to develop magnetic resonance imaging as a tool for biomechanical data acquisition and visualization. Literature reviews also revealed a lack of practical modeling methods for fabric structures, so a basic science research program was also initiated in this area.

Astronaut Ronald Evans photographed during transearth coast EVA

NASA Image and Video Library

1972-12-17

AS17-152-23391 (17 Dec. 1972) --- Astronaut Ronald E. Evans is photographed performing extravehicular activity during the Apollo 17 spacecraft's trans-Earth coast. During his EVA, Evans, command module pilot, retrieved film cassettes from the lunar sounder, mapping camera and panoramic camera. The cylindrical object at Evans' left side is the mapping camera cassette. The total time for the trans-Earth EVA was one hour, seven minutes, 18 seconds, starting at ground elapsed time of 257:25 (2:28 p.m.) and ending at G.E.T. of 258:42 (3:35 p.m.) on Sunday, Dec. 17, 1972.

Astronaut Ronald Evans photographed during transearth coast EVA

NASA Image and Video Library

1972-12-17

AS17-152-23393 (17 Dec. 1972) --- Astronaut Ronald E. Evans is photographed performing extravehicular activity during the Apollo 17 spacecraft's trans-Earth coast. During his EVA, command module pilot Evans retrieved film cassettes from the Lunar Sounder, Mapping Camera, and Panoramic Camera. The cylindrical object at Evans' left side is the Mapping Camera cassette. The total time for the trans-Earth EVA was one hour seven minutes 18 seconds, starting at ground elapsed time of 257:25 (2:28 p.m.) and ending at ground elapsed timed of 258:42 (3:35 p.m.) on Sunday, Dec. 17, 1972.

Construction in space - Toward a fresh definition of the man/machine relation

NASA Technical Reports Server (NTRS)

Watters, H. H.; Stokes, J. W.

1979-01-01

The EVA (extravehicular activity) project forming part of the space construction process is reviewed. The manual EVA constuction, demonstrated by the crew of Skylab 3 by assembling a modest space structure in the form of the twin-pole sunshade, is considered, indicating that the experiment dispelled many doubts about man's ability to execute routine and contingency EVA operations. Tests demonstrating the feasibility of remote teleoperator rendezvous, station keeping, and docking operations, using hand controllers for direct input and television for feedback, are noted. Future plans for designing space construction machines are mentioned.

Electrostatic Discharge Issues in International Space Station Program EVAs

NASA Technical Reports Server (NTRS)

Bacon, John B.

2009-01-01

EVA activity in the ISS program encounters several dangerous ESD conditions. The ISS program has been aggressive for many years to find ways to mitigate or to eliminate the associated risks. Investments have included: (1) Major mods to EVA tools, suit connectors & analytical tools (2) Floating Potential Measurement Unit (3) Plasma Contactor Units (4) Certification of new ISS flight attitudes (5) Teraflops of computation (6) Thousands of hours of work by scores of specialists (7) Monthly management attention at the highest program levels. The risks are now mitigated to a level that is orders of magnitude safer than prior operations

Preparations for Underwater EVA training for the STS 41-G crew

NASA Image and Video Library

1984-07-05

S84-36900 (29 June 1984) ---Astronauts Robert L. Crippen (right) and Jon A. McBride, crew commander and pilot, respectively, for NASA's 41-G Space Shuttle mission, don self contained underwater breathing apparatus (SCUBA) gear prior to their underwater to observe a simulation of an extravehicular activity (EVA) to be performed on their mission. Astronauts Kathryn D. Sullivan and David C. Leestma, two of three mission specialists on the seven-member crew, are scheduled for the EVA. The underwater training took place in the Johnson Space Center's weightless environment training facility (WET-F).

Helms holds onto the Rigid Umbilical during EVA

NASA Image and Video Library

2001-03-11

STS102-314-003 (11 March 2001) --- Astronaut Susan J. Helms works while holding onto a rigid umbilical and with her feet anchored to the remote manipulator system (RMS) robot arm on the Space Shuttle Discovery. This extravehicular activity (EVA), on which Helms was joined by astronaut James S. Voss (out of frame), was the first of two scheduled STS-102 space walks. The pair, destined to become members of the Expedition Two crew aboard the station later in the mission, rode aboard Discovery into orbit and at the time of this EVA were still regarded as STS-102 mission specialists.

STS-64 Extravehicular activity (EVA) training view in WETF

NASA Image and Video Library

1994-08-10

S94-39775 (August 1994) --- Astronaut Carl J. Meade, STS-64 mission specialist, listens to ground monitors during a simulation of a spacewalk scheduled for his September mission. Meade, who shared the rehearsal in the Johnson Space Center's (JSC) Weightless Environment Training Facility (WET-F) pool with crewmate astronaut Mark C. Lee, is equipped with a training version of new extravehicular activity (EVA) hardware called the Simplified Aid for EVA Rescue (SAFER) system. The hardware includes a mobility-aiding back harness and a chest-mounted hand control module. Photo credit: NASA or National Aeronautics and Space Administration

STS-64 Extravehicular activity (EVA) training view in WETF

NASA Image and Video Library

1994-08-10

S94-39762 (August 1994) --- Astronaut Carl J. Meade, STS-64 mission specialist, listens to ground monitors prior to a simulation of a spacewalk scheduled for his September mission. Meade, who shared the rehearsal in Johnson Space Center's (JSC) Weightless Environment Training Facility (WET-F) pool with crewmate astronaut Mark C. Lee (out of frame), is equipped with a training version of new extravehicular activity (EVA) hardware called the Simplified Aid for EVA Rescue (SAFER) system. The hardware includes a mobility-aiding back harness and a chest-mounted hand control module. Photo credit: NASA or National Aeronautics and Space Administration

Astronaut William S. McArthur in training for contingency EVA in WETF

NASA Image and Video Library

1993-09-10

S93-43840 (6 Sept 1993) --- Astronaut William S. McArthur, mission specialist, participates in training for contingency Extravehicular Activity (EVA) for the STS-58 mission. For simulation purposes, McArthur was about to be submerged to a point of neutral buoyancy in the Johnson Space Center's (JSC) Weightless Environment Training Facility (WET-F). Though the Spacelab Life Sciences (SLS-2) mission does not include a planned EVA, all crews designate members to learn proper procedures to perform outside the spacecraft in the event of failure of remote means to accomplish those tasks.

Regenerable non-venting thermal control subsystem for extravehicular activity

NASA Technical Reports Server (NTRS)

Roebelen, George J.; Bayes, Stephen A.; Lawson, B. Mike

1986-01-01

Routine and complex EVAs call for more effective heat rejection systems in order to maximize mission productivity; an optimum EVA mobility unit (EMU) thermal control subsystem must require no expendables and introduce no contaminants into the environment, while conforming to minimum size limits and allowing easy regeneration. Attention is presently given to two thermal control subsystems, one of which can be integrated with the existing Space Shuttle Orbiter EMU to provide a 3-hour nonventing heat rejection capability, while the other can furnish the entire heat rejection capability requirement for an 8-hour Space Station EVA.

Systems and methods for circuit lifetime evaluation

NASA Technical Reports Server (NTRS)

Heaps, Timothy L. (Inventor); Sheldon, Douglas J. (Inventor); Bowerman, Paul N. (Inventor); Everline, Chester J. (Inventor); Shalom, Eddy (Inventor); Rasmussen, Robert D. (Inventor)

2013-01-01

Systems and methods for estimating the lifetime of an electrical system in accordance with embodiments of the invention are disclosed. One embodiment of the invention includes iteratively performing Worst Case Analysis (WCA) on a system design with respect to different system lifetimes using a computer to determine the lifetime at which the worst case performance of the system indicates the system will pass with zero margin or fail within a predetermined margin for error given the environment experienced by the system during its lifetime. In addition, performing WCA on a system with respect to a specific system lifetime includes identifying subcircuits within the system, performing Extreme Value Analysis (EVA) with respect to each subcircuit to determine whether the subcircuit fails EVA for the specific system lifetime, when the subcircuit passes EVA, determining that the subcircuit does not fail WCA for the specified system lifetime, when a subcircuit fails EVA performing at least one additional WCA process that provides a tighter bound on the WCA than EVA to determine whether the subcircuit fails WCA for the specified system lifetime, determining that the system passes WCA with respect to the specific system lifetime when all subcircuits pass WCA, and determining that the system fails WCA when at least one subcircuit fails WCA.

Evaluation of Hardware and Procedures for Astronaut Assembly and Repair of Large Precision Reflectors

NASA Technical Reports Server (NTRS)

Lake, Mark S.; Heard, Walter L., Jr.; Watson, Judith J.; Collins, Timothy J.

2000-01-01

A detailed procedure is presented that enables astronauts in extravehicular activity (EVA) to efficiently assemble and repair large (i.e., greater than 10m-diameter) segmented reflectors, supported by a truss, for space-based optical or radio-frequency science instruments. The procedure, estimated timelines, and reflector hardware performance are verified in simulated 0-g (neutral buoyancy) assembly tests of a 14m-diameter, offset-focus, reflector test article. The test article includes a near-flight-quality, 315-member, doubly curved support truss and 7 mockup reflector panels (roughly 2m in diameter) representing a portion of the 37 total panels needed to fully populate the reflector. Data from the tests indicate that a flight version of the design (including all reflector panels) could be assembled in less than 5 hours - less than the 6 hours normally permitted for a single EVA. This assembly rate essentially matches pre-test predictions that were based on a vast amount of historical data on EVA assembly of structures produced by NASA Langley Research Center. Furthermore, procedures and a tool for the removal and replacement of a damaged reflector panel were evaluated, and it was shown that EVA repair of this type of reflector is feasible with the use of appropriate EVA crew aids.

The position of a key tyrosine in dTDP-4-Keto-6-deoxy-D-glucose-5-epimerase (EvaD) alters the substrate profile for this RmlC-like enzyme.

PubMed

Merkel, Alexandra B; Major, Louise L; Errey, James C; Burkart, Michael D; Field, Robert A; Walsh, Christopher T; Naismith, James H

2004-07-30

Vancomycin, the last line of defense antibiotic, depends upon the attachment of the carbohydrate vancosamine to an aglycone skeleton for antibacterial activity. Vancomycin is a naturally occurring secondary metabolite that can be produced by bacterial fermentation. To combat emerging resistance, it has been proposed to genetically engineer bacteria to produce analogues of vancomycin. This requires a detailed understanding of the biochemical steps in the synthesis of vancomycin. Here we report the 1.4 A structure and biochemical characterization of EvaD, an RmlC-like protein that is required for the C-5' epimerization during synthesis of dTDP-epivancosamine. EvaD, although clearly belonging to the RmlC class of enzymes, displays very low activity in the archetypal RmlC reaction (double epimerization of dTDP-6-deoxy-4-keto-D-glucose at C-3' and C-5'). The high resolution structure of EvaD compared with the structures of authentic RmlC enzymes indicates that a subtle change in the enzyme active site repositions a key catalytic Tyr residue. A mutant designed to re-establish the normal position of the Tyr increases the RmlC-like activity of EvaD.

STS-109 Crew Interviews - Linnehan

NASA Technical Reports Server (NTRS)

2002-01-01

STS-109 Mission Specialist 3 (MS3) Richard M. Linnehan is seen during a prelaunch interview. He answers questions about his lifelong desire to become an astronaut and his career path, which included becoming a zoo veterinarian. He gives details on the Columbia Orbiter mission, which has as its main purpose the maintenance and augmentation of the Hubble Space Telescope (HST). As MS3, his primary role in the mission pertains to EVAs (Extravehicular Activities) 1, 3, and 5. During EVA 1, Linnehan and another crewmember will replace one of two flexible solar arrays on the HST with a smaller, more efficient rigid solar array. The second solar array will be replaced on EVA 2 by other crewmembers. EVA 3 will involve the replacement of the Power Control Unit (PCU), and will require the first complete powering down of HST since its deployment. The possibility of a serious problem occurring is greatest during this portion of the mission because the original PCU was not built to be replaced. In EVA 5, Linnehan and another crewmember will install a replacement cooling system on NICMOS (Near Infrared Camera Multi-Object Spectrometer), which has not been operational. Linnehan discusses his role during the mission as well as that of his crewmates, and provides an abbreviated timeline, including possible contingencies.

Effect of fibre treatments on tensile properties of ethylene vinyl acetate/natural rubber/mengkuang leaf fibre (EVA/NR/MLF) thermoplastic elastomer composites

NASA Astrophysics Data System (ADS)

Hashim, Faiezah; Ismail, Hanafi; Rusli, Arjulizan

2017-07-01

Nowadays, a great attention has been dedicated to natural fibers as reinforcement for polymer composites. Natural fibers, compared to glass fibers, exhibit better mechanical properties, such as stiffness, impact strength, flexibility and modulus. However, certain drawbacks, such as the incompatibility between fibers and polymer matrices, the tendency to form aggregates during processing and the poor resistance to moisture, reduce the use of these natural fibers as reinforcements in polymers. Several treatments and modifications are being used to improve the adhesion between fibre and matrix. In this work, the effect of bleaching treatments using hydrogen peroxide in the Mengkuang leaf fibre (MLF) was evaluated on tensile properties of Ethylene Vinyl Acetate (EVA)/Natural Rubber (NR)/MLF composites. Treated MLF were mixed with the EVA/NR blend in Haake internal mixer at 120 °C and rotor speed of 50 rpm for 10 minutes. Fibre morphology and the fibre/matrix interface ware further characterized by scanning electron microscopy (SEM). The tensile strength was increased by about 8% as compared to the composites with untreated fibers. The increased adhesion between fiber and matrix was also observed by SEM. Thus, EVA/NR/MLF composites reinforced with the treated fibres exhibited better tensile properties than untreated EVA/NR/MLF composites.