Operations planning simulation model extension study. Volume 1: Long duration exposure facility ST-01-A automated payload

NASA Technical Reports Server (NTRS)

Marks, D. A.; Gendiellee, R. E.; Kelly, T. M.; Giovannello, M. A.

1974-01-01

Ground processing and operation activities for selected automated and sortie payloads are evaluated. Functional flow activities are expanded to identify payload launch site facility and support requirements. Payload definitions are analyzed from the launch site ground processing viewpoint and then processed through the expanded functional flow activities. The requirements generated from the evaluation are compared with those contained in the data sheets. The following payloads were included in the evaluation: Long Duration Exposure Facility; Life Sciences Shuttle Laboratory; Biomedical Experiments Scientific Satellite; Dedicated Solar Sortie Mission; Magnetic Spectrometer; and Mariner Jupiter Orbiter. The expanded functional flow activities and descriptions for the automated and sortie payloads at the launch site are presented.

Radioactivities of Long Duration Exposure Facility (LDEF) materials: Baggage and bonanzas

NASA Technical Reports Server (NTRS)

Smith, Alan R.; Hurley, Donna L.

1992-01-01

Radioactivities in materials onboard the returned Long Duration Exposure Facility (LDEF) satellite were studied by a variety of techniques. Among the most powerful is low-background Ge-semiconductor detector gamma-ray spectrometry, illustrated here by results obtained at the Lawrence Berkeley Laboratory's (LBL) Low Background Facilities. The observed radioactivities are of two origins: those radionuclides produced by nuclear reactions with the radiation field in orbit, and radionuclides present initially as 'contaminants' in materials used for construction of the spacecraft and experimental assemblies. In the first category are experiment-related monitor foils and tomato seeds, and such spacecraft materials as aluminum, stainless steel, and titanium. In the second category are aluminum, beryllium, titanium, vanadium, and some special glasses.

Investigation of the effects of long duration space exposure on active optical system components

NASA Technical Reports Server (NTRS)

Blue, M. D.

1994-01-01

This experiment was exposed to the space environment for 6 years on the Long Duration Exposure Facility (LDEF). It investigated quantitatively the effects of the long-duration space exposure on the relevant performance parameters of a representative set of electron-optic system components, including lasers, radiation detectors, filters, modulators, windows, and other related components. It evaluated the results and implications of the measurements indicating real or suspected degradation mechanisms. This information will be used to establish guidelines for the selection and use of components for space-based, electro-optic systems.

Calculated values of atomic oxygen fluences and solar exposure on selected surfaces of LDEF

NASA Technical Reports Server (NTRS)

Gillis, J. R.; Pippin, H. G.; Bourassa, R. J.; Gruenbaum, P. E.

1995-01-01

Atomic oxygen (AO) fluences and solar exposure have been modeled for selected hardware from the Long Duration Exposure Facility (LDEF). The atomic oxygen exposure was modeled using the microenvironment modeling code SHADOWV2. The solar exposure was modeled using the microenvironment modeling code SOLSHAD version 1.0.

Exposure to nature gardens has time-dependent associations with mood improvements for people with mid- and late-stage dementia: Innovative practice.

PubMed

White, Piran Cl; Wyatt, Jonathan; Chalfont, Garuth; Bland, J Martin; Neale, Christopher; Trepel, Dominic; Graham, Hilary

2017-01-01

Exposure to green space and nature has a potential role to play in the care of people with dementia, with possible benefits including improved mood and slower disease progression. In this observational study at a dementia care facility in the UK, we used carer-assessed measures to evaluate change in mood of residents with mid- to late-stage dementia following exposure to a nature garden. We found that exposure to nature was associated with a beneficial change in patient mood. There was a non-linear relationship between time spent outdoors and mood outcome. Improvements in patient mood were associated with relatively short duration exposures to nature, and no additional measureable increases in mood were found with exposures beyond 80-90 minutes duration. Whilst further investigation is required before causality can be determined, these results raise important questions for policy about the integration of outdoor space into the design of dementia care facilities and programmes.

Long Duration Exposure Facility (LDEF) attitude measurements of the Interplanetary Dust Experiment

NASA Technical Reports Server (NTRS)

Kassel, Philip C., Jr.; Motley, William R., III; Singer, S. Fred; Mulholland, J. Derral; Oliver, John P.; Weinberg, Jerry L.; Cooke, William J.; Wortman, Jim J.

1993-01-01

Analysis of the data from the Long Duration Exposure Facility (LDEF) Interplanetary Dust Experiment (IDE) sun sensors has allowed a confirmation of the attitude of LDEF during its first year in orbit. Eight observations of the yaw angle at specific times were made and are tabulated in this paper. These values range from 4.3 to 12.4 deg with maximum uncertainty of plus or minus 2.0 deg and an average of 7.9 deg. No specific measurements of pitch or roll were made but the data indicates that LDEF had an average pitch down attitude of less than 0.7 deg.

Overview of the systems special investigation. [long duration exposure facility

NASA Technical Reports Server (NTRS)

Mason, James B.; Dursch, Harry; Edelman, Joel

1992-01-01

The Systems Special Investigation Group (SIG), formed by the Long Duration Exposure Facility (LDEF) Project Office to perform post flight analysis of systems hardware, was chartered to investigate the effects of the extended LDEF mission on both satellite and experiment systems and to coordinate and integrate all systems analysis performed in post flight investigations. Almost all of the top level functional testing of the active experiments has been completed, but many components are still under investigation by either the Systems SIG or individual experimenters. Results reported to date have been collected and integrated by the Systems SIG and an overview of the current results and the status of the Systems Investigation are presented in this paper.

Long Duration Exposure Facility (LDEF) low-temperature heat pipe experiment package power system results

NASA Technical Reports Server (NTRS)

Tiller, Smith E.; Sullivan, David

1992-01-01

An overview of a self-contained Direct Energy Transfer Power System which was developed to provide power to the Long Duration Exposure Facility (LDEF) Low-Temperature Heat Pipe Experiment Package is presented. The power system operated successfully for the entire mission. Data recorded by the onboard recorder shows that the system operated within design specifications. Other than unanticipated overcharging of the battery, the power system operated as expected for nearly 32,000 low earth orbit cycles, and was still operational when tested after the LDEF recovery. Some physical damage was sustained by the solar array panels due to micrometeoroid hits, but there were not electrical failures.

Long Duration Exposure Facility (LDEF) structural verification test report

NASA Technical Reports Server (NTRS)

Jones, T. C.; Lucy, M. H.; Shearer, R. L.

1983-01-01

Structural load tests on the Long Duration Exposure Facility's (LDEF) primary structure were conducted. These tests had three purposes: (1) demonstrate structural adequacy of the assembled LDEF primary structure when subjected to anticipated flight loads; (2) verify analytical models and methods used in loads and stress analysis; and (3) perform tests to comply with the Space Transportation System (STS) requirements. Test loads were based on predicted limit loads which consider all flight events. Good agreement is shown between predicted and observed load, strain, and deflection data. Test data show that the LDEF structure was subjected to 1.2 times limit load to meet the STS requirements. The structural adequacy of the LDEF is demonstrated.

Analysis of selected materials flown on interior locations of the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Smith, H. A.; Nelson, K. M.; Eash, D.; Pippin, H. G.

1994-01-01

This report documents the post-flight condition of selected hardware taken from interior locations on the Long Duration Exposure Facility (LDEF). This hardware was generally in excellent condition. Outgassing data is presented for heat shrink tubing and fiberglass composite shims. Variation in total mass loss (TML) values for heat shrink tubing were correlated with location. Nylon grommets were evaluated for mechanical integrity; slight embrittlement was observed for flight specimens. Multi-layer insulation blankets, wire bundles, and paints in non-exposed interior locations were all in visibly good condition. Silicon-containing contaminant films were observed on silver-coated hex nuts at the space- and Earth-end interior locations.

Results of the TTF-TCNQ and the calcium carbonate crystallization on the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Nielsen, Kjeld Flemming; Lind, M. David

1992-01-01

Experiment A0139A on the Long Duration Exposure Facility (LDEF) carried four large containers into orbit five years with crystal growth solutions for lead sulfide, calcium carbonate, and TTF-TCNQ. Although temperature data was lost, the experimental program had been working since the valves in all containers had been opened. All four experiments produced crystals of varying quality. The calcium carbonate crystals had the best appearance. The TTF-TCNQ crystals were packed together near the valve openings of the container. When taken apart, the single crystals showed some unusual morphological properties. X ray investigations as well as conductivity measurements on long duration space grown TTF-TCNQ crystals will be presented. Comparisons will be made with our previous space solution growth experiments. The TTF-TCNQ crystals are no longer of the highest interest, so this activity has been terminated in favor of calcium carbonate and calcium phosphate crystallizations.

Low Prevalence of Chronic Beryllium Disease among Workers at a Nuclear Weapons Research and Development Facility

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

Arjomandi, M; Seward, J P; Gotway, M B

2010-01-11

To study the prevalence of beryllium sensitization (BeS) and chronic beryllium disease (CBD) in a cohort of workers from a nuclear weapons research and development facility. We evaluated 50 workers with BeS with medical and occupational histories, physical examination, chest imaging with HRCT (N=49), and pulmonary function testing. Forty of these workers also underwent bronchoscopy for bronchoalveolar lavage (BAL) and transbronchial biopsies. The mean duration of employment at the facility was 18 yrs and the mean latency (from first possible exposure) to time of evaluation was 32 yrs. Five of the workers had CBD at the time of evaluation (basedmore » on histology or HRCT); three others had evidence of probable CBD. These workers with BeS, characterized by a long duration of potential Be exposure and a long latency, had a low prevalence of CBD.« less

Low Prevalence of Chronic Beryllium Disease Among Workers at aNuclearWeaponsResearchandDevelopmentFacility

PubMed Central

Arjomandi, Mehrdad; Seward, James; Gotway, Michael B.; Nishimura, Stephen; Fulton, George P.; Thundiyil, Josef; King, Talmadge E.; Harber, Philip; Balmes, John R.

2012-01-01

Objective To study the prevalence of beryllium sensitization (BeS) and chronic beryllium disease (CBD) in a cohort of workers from a nuclear weapons research and development facility. Methods We evaluated 50 workers with BeS with medical and occupational histories, physical examination, chest imaging with high-resolution computed tomography (N = 49), and pulmonary function testing. Forty of these workers also underwent bronchoscopy for bronchoalveolar lavage and transbronchial biopsies. Results The mean duration of employment at the facility was 18 years and the mean latency (from first possible exposure) to time of evaluation was 32 years. Five of the workers had CBD at the time of evaluation (based on histology or high-resolution computed tomography); three others had evidence of probable CBD. Conclusions These workers with BeS, characterized by a long duration of potential Be exposure and a long latency, had a low prevalence of CBD. PMID:20523233

Solidification under zero gravity: A Long Duration Exposure Facility (LDEF) experiment for an early space shuttle mission. [project planning

NASA Technical Reports Server (NTRS)

Bailey, J. A.

1976-01-01

Project planning for two series of simple experiments on the effect of zero gravity on the melting and freezing of metals and nonmetals is described. The experiments will be performed in the Long Duration Exposure Facility, and their purpose will be to study: (1) the general morphology of metals and nonmetals during solidification, (2) the location of ullage space (liquid-vapor interfaces), and (3) the magnitude of surface tension driven convection during solidification of metals and nonmetals. The preliminary design of the experiments is presented. Details of the investigative approach, experimental procedure, experimental hardware, data reduction and analysis, and anticipated results are given. In addition a work plan and cost analysis are provided.

Vacuum Ultraviolet (VUV) radiation-induced degradation of Fluorinated Ethylene Propylene (FEP) Teflon aboard the Long Duration Exposure Facility (LDEF)

NASA Technical Reports Server (NTRS)

Brinza, David E.; Stiegman, A. E.; Staszak, Paul R.; Laue, Eric G.; Liang, Ranty H.

1992-01-01

Examination of fluorinated ethylene propylene (FEP) copolymer specimens recovered from the Long Duration Exposure Facility (LDEF) provides evidence for degradation attributed to extended solar vacuum ultraviolet (VUV) irradiation. Scanning electron microscope (SEM) images of sheared FEP film edges reveal the presence of a highly embrittled layer on the exposed surface of specimens obtained from the trailing edge of the LDEF. Similar images obtained for leading edge and control FEP films do not exhibit evidence for such an embrittled layer. Laboratory VUV irradiation of FEP films is found to produce a damage layer similar to that witnessed in the LDEF trailing edge films. Spectroscopic analyses of irradiated films provide data to advance a photochemical mechanism for degradation.

The preliminary Long Duration Exposure Facility (LDEF) materials data base

NASA Technical Reports Server (NTRS)

Funk, Joan G.; Strickland, John W.; Davis, John M.

1992-01-01

A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated for LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux), and author(s) or principal investigator(s). The LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which was computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. This paper describes the LDEF Materials Data Base and includes step-by-step example searches using the data base. Information on how to become an authorized user of the system is included.

Applicability of Long Duration Exposure Facility environmental effects data to the design of Space Station Freedom electrical power system

NASA Technical Reports Server (NTRS)

Christie, Robert J.; Lu, Cheng-Yi; Aronoff, Irene

1992-01-01

Data defining space environmental effects on the Long Duration Exposure Facility (LDEF) are examined in terms of the design of the electrical power system (EPS) of the Space Station Freedom (SSF). The significant effects of long-term exposure to space are identified with respect to the performance of the LDEF's materials, components, and systems. A total of 57 experiments were conducted on the LDEF yielding information regarding coatings, thermal systems, electronics, optics, and power systems. The resulting database is analyzed in terms of the specifications of the SSF EPS materials and subsystems and is found to be valuable in the design of control and protection features. Specific applications are listed for findings regarding the thermal environment, atomic oxygen, UV and ionizing radiation, debris, and contamination. The LDEF data are shown to have a considerable number of applications to the design and planning of the SSF and its EPS.

Socioeconomic status, occupational characteristics, and sleep duration in African/Caribbean immigrants and US White health care workers.

PubMed

Ertel, Karen A; Berkman, Lisa F; Buxton, Orfeu M

2011-04-01

o advance our understanding of the interplay of socioeconomic factors, occupational exposures, and race/ethnicity as they relate to sleep duration. We hypothesize that non Hispanic African/Caribbean immigrant employees in long term health care have shorter sleep duration than non Hispanic white employees, and that low education, low income, and occupational exposures including night work and job strain account for some of the African/Caribbean immigrant-white difference in sleep duration. Cross sectional Four extended care facilities in Massachusetts, United States 340 employees in extended care facilities Sleep duration was assessed with wrist actigraphy for a mean of 6.3 days. In multivariable regression modeling controlling for gender and age, African/Caribbean immigrants slept 64.4 fewer minutes (95% CI: -81.0, -47.9) per night than white participants; additional control for education and income reduced the racial gap to 50.9 minutes (-69.2, -32.5); additional control for the occupational factors of hours worked per week and working the night shift reduced the racial gap to 37.7 minutes (-57.8, -17.6). his study provides support for the hypothesis that socioeconomic and occupational characteristics explain some of the African/ Caribbean immigrant-white difference in sleep duration in the United States, especially among health care workers.

Results of the TTF-TCNQ- and the calcium carbonate-crystallization on the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Nielsen, Kjeld Flemming; Lind, M. David

1991-01-01

Experiment AO139A on the Long Duration Exposure Facility (LDEF) carried four large containers into orbit for five years with crystal growth solutions for lead sulfide, calcium carbonate, and tetra thiafulvalene- tetra cyanoquino methane (TTF-TCNQ). The LDEF was in excellent condition after the long orbital stay, and although the temperature data was lost, the experiment program had been working since the valves in all containers were opened. All four experiments produced crystals; however, they were of varying quality. The calcium carbonate crystals had the best appearance. The TTF-TCNQ crystals were packed together near the valve openings of the container. When taken apart, the single crystals showed some unusual morphological properties. X-ray investigations as well as conductivity measurements on the long duration space grown TTF-TCNQ crystals are presented, and pictures of the calcium carbonate are shown. Comparisons are made with previous space solution growth experiments on the European Spacelab Mission and the Apollo-Soyuz Test Project.

Analysis of systems hardware flown on LDEF. Results of the systems special investigation group

NASA Technical Reports Server (NTRS)

Dursch, Harry W.; Spear, W. Steve; Miller, Emmett A.; Bohnhoff-Hlavacek, Gail L.; Edelman, Joel

1992-01-01

The Long Duration Exposure Facility (LDEF) was retrieved after spending 69 months in low Earth orbit (LEO). LDEF carried a remarkable variety of mechanical, electrical, thermal, and optical systems, subsystems, and components. The Systems Special Investigation Group (Systems SIG) was formed to investigate the effects of the long duration exposure to LEO on systems related hardware and to coordinate and collate all systems analysis of LDEF hardware. Discussed here is the status of the LDEF Systems SIG investigation through the end of 1991.

Analysis of systems hardware flown on LDEF. Results of the systems special investigation group

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

Dursch, H.W.; Spear, W.S.; Miller, E.A.

1992-04-01

The Long Duration Exposure Facility (LDEF) was retrieved after spending 69 months in low Earth orbit (LEO). LDEF carried a remarkable variety of mechanical, electrical, thermal, and optical systems, subsystems, and components. The Systems Special Investigation Group (Systems SIG) was formed to investigate the effects of the long duration exposure to LEO on systems related hardware and to coordinate and collate all systems analysis of LDEF hardware. Discussed here is the status of the LDEF Systems SIG investigation through the end of 1991.

New experiments selected for 1980 operational shuttle flight

NASA Technical Reports Server (NTRS)

1978-01-01

Experiments selected for NASA's Long Duration Exposure Facility mission are described. Technical areas represented by the experiments include materials, thermal control coatings, detectors, power, micrometeoroids, electronics, lubrication, optics, and space debris detection.

Lithium cell tests at Langley Research Center. [for the long duration exposure facility

NASA Technical Reports Server (NTRS)

Bene, J.

1977-01-01

The long duration exposure facility mission places temperature requirements of from -30 F to +150 F on the batteries to be used. A hermetically sealed lithium sulfur dioxide cell was tested to predict what the temperature of the battery would be over a given spectrum of temperatures of operation. Near the end of cell discharge, as the voltage started collapsing, a very high heat output rise due to chemical reaction took place. However, if the cells were thermally insulated, they vented, ignited, and burned if an attempt was made to discharge them all the way. The cells do not go into reversal. It was determined that the root of the problem was probably the chemical reaction between the lithium and the acetonitrite solvent. A redesigned cell is discussed as well as some alternates.

Analysis of the passive stabilization of the long duration exposure facility

NASA Technical Reports Server (NTRS)

Siegel, S. H.; Vishwanath, N. S.

1977-01-01

The nominal Long Duration Exposure Facility (LDEF) configurations and the anticipated orbit parameters are presented. A linear steady state analysis was performed using these parameters. The effects of orbit eccentricity, solar pressure, aerodynamic pressure, magnetic dipole, and the magnetically anchored rate damper were evaluated to determine the configuration sensitivity to variations in these parameters. The worst case conditions for steady state errors were identified, and the performance capability calculated. Garber instability bounds were evaluated for the range of configuration and damping coefficients under consideration. The transient damping capabilities of the damper were examined, and the time constant as a function of damping coefficient and spacecraft moment of inertia determined. The capture capabilities of the damper were calculated, and the results combined with steady state, transient, and Garber instability analyses to select damper design parameters.

Long Duration Exposure Facility post-flight data as it influences the Tropical Rainfall Measuring Mission

NASA Technical Reports Server (NTRS)

Straka, Sharon A.

1995-01-01

The Tropical Rainfall Measuring Mission (TRMM) is an earth observing satellite that will be in a low earth orbit (350 kilometers) during the next period of maximum solar activity. The TRMM observatory is expected to experience an atomic oxygen fluence of 8.9 x 10(exp 22) atoms per square centimeter. This fluence is ten times higher than the atomic oxygen impingement incident to the Long Duration Exposure Facility (LDEF). Other environmental concerns on TRMM include: spacecraft glow, silicon oxide contaminant build-up, severe spacecraft material degradation, and contamination deposition resulting from molecular interactions with the dense ambient atmosphere. Because of TRMM's predicted harsh environment, TRMM faces many unique material concerns and subsystem design issues. The LDEF data has influenced the design of TRMM and the TRMM material selection process.

Inactivation of Ichthyophonus spores using sodium hypochlorite and polyvinyl pyrrolidone iodine

USGS Publications Warehouse

Hershberger, P.K.; Pacheco, C.A.; Gregg, J.L.

2008-01-01

Chlorine and iodine solutions were effective at inactivating Ichthyophonus spores in vitro. Inactivation in sea water increased directly with halogen concentration and exposure duration, with significant differences (P < 0.05) from controls occurring at all chlorine concentrations and exposure durations tested (1.5-13.3 ppm for 1-60 min) and at most iodine concentrations and exposure durations tested (1.2 ppm for 60 min and 5.9-10.7 ppm for 1-60 min). However, 10-fold reductions in spore viability occurred only after exposure to halogen solutions at higher concentrations and/or longer durations (13 ppm total chlorine for 1-60 min, 5.9 ppm total iodine for 60 min, and 10.7 ppm total iodine for 1-60 min). Inactivation efficacy was greater when halogen solutions were prepared in fresh water, presumably because of combined effects of halogen-induced inactivation and general spore instability in fresh water. The results have practical implications for disinfection and biocontainment in research laboratories and other facilities that handle live Ichthyophonus cultures and/or infected fish.

Space environmental effects on the integrity of chromic acid anodized coatings

NASA Technical Reports Server (NTRS)

Plagemann, W. L.

1993-01-01

This report describes the condition of chromic acid anodized aluminum subsequent to a 69-month exposure to low Earth orbit (LEO) on the Long Duration Exposure Facility. Optical properties and the condition of anodized coating are reported. This material was exposed to each environmental parameter present in LEO. Only slight changes in the material were observed.

Long-duration orbital effects on optical coating materials

NASA Technical Reports Server (NTRS)

Herzig, Howard; Toft, Albert R.; Fleetwood, Charles M., Jr.

1993-01-01

We flew specimens of eight different optical coating materials in low earth orbit as part of the Long Duration Exposure Facility manifest to determine their ability to withstand exposure to the residual atomic 0 and other environmental effects at those altitudes. We included samples of Al, Au, Ir, Os, Pt, Al + MgF2, Al + SiO(x), and chemical-vapor-deposited SiC, representing reflective optical applications from the vacuum ultraviolet through the visible portions of the spectrum. We found that the majority of the materials suffered sufficient reflectance degradation to warrant careful consideration in the design of future space-flight instrumentation.

Microgravity Simulation Facility (MSF)

NASA Technical Reports Server (NTRS)

Richards, Stephanie E. (Compiler); Levine, Howard G.; Zhang, Ye

2016-01-01

The Microgravity Simulator Facility (MSF) at Kennedy Space Center (KSC) was established to support visiting scientists for short duration studies utilizing a variety of microgravity simulator devices that negate the directional influence of the "g" vector (providing simulated conditions of micro or partial gravity). KSC gravity simulators can be accommodated within controlled environment chambers allowing investigators to customize and monitor environmental conditions such as temperature, humidity, CO2, and light exposure.

Socioeconomic Status, Occupational Characteristics, and Sleep Duration in African/Caribbean Immigrants and US White Health Care Workers

PubMed Central

Ertel, Karen A.; Berkman, Lisa F.; Buxton, Orfeu M.

2011-01-01

Study Objectives: o advance our understanding of the interplay of socioeconomic factors, occupational exposures, and race/ethnicity as they relate to sleep duration. We hypothesize that non Hispanic African/Caribbean immigrant employees in long term health care have shorter sleep duration than non Hispanic white employees, and that low education, low income, and occupational exposures including night work and job strain account for some of the African/Caribbean immigrant–white difference in sleep duration. Design: Cross sectional Setting: Four extended care facilities in Massachusetts, United States Participants: 340 employees in extended care facilities Measurements and Results: Sleep duration was assessed with wrist actigraphy for a mean of 6.3 days. In multivariable regression modeling controlling for gender and age, African/Caribbean immigrants slept 64.4 fewer minutes (95% CI: −81.0, −47.9) per night than white participants; additional control for education and income reduced the racial gap to 50.9 minutes (−69.2, −32.5); additional control for the occupational factors of hours worked per week and working the night shift reduced the racial gap to 37.7 minutes (−57.8, −17.6). Conclusions: his study provides support for the hypothesis that socioeconomic and occupational characteristics explain some of the African/ Caribbean immigrant–white difference in sleep duration in the United States, especially among health care workers. Citation: Ertel KA; Berkman LF; Buxton OM. Socioeconomic status, occupational characteristics, and sleep duration in African/Caribbean immi grants and US white health care workers. SLEEP 2011; 34(4):509-518. PMID:21461330

Thermoluminescent dosimetry for LDEF experiment M0006

NASA Technical Reports Server (NTRS)

Chang, J. Y.; Giangano, D.; Kantorcik, T.; Stauber, M.; Snead, L.

1992-01-01

Experiment M0006 on the Long Duration Exposure Facility had as its objective the investigation of space radiation effects on various electronic and optical components, as well as on seed germination. The Grumman Corporate Research Center provided the radiation dosimetric measurements for M0006, comprising the preparation of thermoluminescent dosimeters (TLD) and the subsequent measurement and analysis of flight exposed and control samples. In addition, various laboratory exposures of TLD's with gamma rays and protons were performed to obtain a better understanding of the flight exposures.

Long-term exposure of bacterial spores to space

NASA Technical Reports Server (NTRS)

Horneck, G.; Buecker, H.; Reitz, G.

1992-01-01

With the NASA mission of the Long Duration Exposure Facility (LDEF), the authors have obtained the opportunity to expose Bacillus subtilis spores for nearly six years to the space environment and to analyze their responses after retrieval. The experiment was mounted onto a side tray of LDEF facing space. Data shows that the chances of microorganisms surviving in free space will be greatly increased by adequate shielding against solar ultraviolet light.

Radioactivities of Long Duration Exposure Facility (LDEF) materials: Baggage and bonanzas

NASA Technical Reports Server (NTRS)

Smith, Alan R.; Hurley, Donna L.

1991-01-01

Radioactivities in materials onboard the returned Long Duration Exposure Facility (LDEF) satellite were studied by a variety of techniques. Among the most powerful is low background Ge semiconductor detector gamma ray spectrometry. The observed radioactivities are of two origins: those radionuclides produced by nuclear reactions with the radiation field in orbit and radionuclides present initially as contaminants in materials used for construction of the spacecraft and experimental assemblies. In the first category are experiment related monitor foils and tomato seeds, and such spacecraft materials as Al, stainless steel, and Ti. In the second category are Al, Be, Ti, Va, and some special glasses. Consider that measured peak-area count rates from both categories range from a high value of about 1 count per minute down to less than 0.001 count per minute. Successful measurement of count rates toward the low end of this range can be achieved only through low background techniques, such as used to obtain the results presented here.

Radioactivities of Long Duration Exposure Facility (LDEF) materials: Baggage and bonanzas

NASA Astrophysics Data System (ADS)

Smith, Alan R.; Hurley, Donna L.

1991-06-01

Radioactivities in materials onboard the returned Long Duration Exposure Facility (LDEF) satellite were studied by a variety of techniques. Among the most powerful is low background Ge semiconductor detector gamma ray spectrometry. The observed radioactivities are of two origins: those radionuclides produced by nuclear reactions with the radiation field in orbit and radionuclides present initially as contaminants in materials used for construction of the spacecraft and experimental assemblies. In the first category are experiment related monitor foils and tomato seeds, and such spacecraft materials as Al, stainless steel, and Ti. In the second category are Al, Be, Ti, Va, and some special glasses. Consider that measured peak-area count rates from both categories range from a high value of about 1 count per minute down to less than 0.001 count per minute. Successful measurement of count rates toward the low end of this range can be achieved only through low background techniques, such as used to obtain the results presented here.

Airborne concentrations of benzene for dock workers at the ExxonMobil refinery and chemical plant, Baton Rouge, Louisiana, USA (1977-2005).

PubMed

Widner, Thomas E; Gaffney, Shannon H; Panko, Julie M; Unice, Kenneth M; Burns, Amanda M; Kreider, Marisa; Marshall, J Ralph; Booher, Lindsay E; Gelat, Richard H; Paustenbach, Dennis J

2011-03-01

Benzene is a natural constituent of crude oil and natural gas (0.1-3.0% by volume). Materials that are refined from crude oil and natural gas contain some residual benzene. Few datasets have appeared in the peer-reviewed literature characterizing exposures to benzene at specific refineries or during specific tasks. In this study, historical samples of airborne benzene collected from 1977-2005 at the ExxonMobil Baton Rouge, Louisiana, USA, docks were evaluated. Workers were categorized into 11 job titles, and both non-task (≤180 min sample duration) and task-related (<180 min) benzene concentrations were assessed. Approximately 800 personal air samples (406 non-task and 397 task-related) were analyzed. Non-task samples showed that concentrations varied significantly across job titles and generally resulted from exposures during short-duration tasks such as tank sampling. The contractor - tankerman job title had the highest average concentration [N=38, mean 1.4 parts per million (ppm), standard deviation (SD) 2.6]. Task-related samples indicated that the highest exposures were associated with the disconnection of cargo loading hoses (N=134, mean 11 ppm, SD 32). Non-task samples for specific job categories showed that concentrations have decreased over the past 30 years. Recognizing the potential for benzene exposure, this facility has required workers to use respiratory protective equipment during selected tasks and activities; thus, the concentrations measured were likely greater than those that the employee actually experienced. This study provides a job title- and task-focused analysis of occupational exposure to benzene during dock facility operations that is insightful for understanding the Baton Rouge facility and others similar to it over the past 30 years.

The Long Duration Exposure Facility (LDEF) photographic survey special publication

NASA Technical Reports Server (NTRS)

Oneal, Robert L.; Levine, Arlene S.; Kiser, Carol C.

1995-01-01

During the construction, integration, launch, retrieval and deintegration of the Long Duration Exposure Facility (LDEF), photographic surveys were made. Approximately 10,000 photographs were taken during the various phases of the LDEF project. These surveys are of technical and scientific importance because they revealed the pre and post flight conditions of the experiment trays as well as the spacecraft. Visual inspection of the photographs reveal valuable data such as space environment's effects and the earth atmosphere's effects post-retrieval. Careful files and records have been kept of these photographs. Each photograph has a Kennedy Space Center photo number or a Johnson Spaceflight Center photo number as well as a Langley Research Center photo number. The tray number, row number, and experiment number are also noted. Out of the 10,000 photographs taken, approximately 700 selected photographs were chosen for publication in a NASA Special Publication (SP) because they reveal the effects of space exposure to the viewer. These photographs will give researchers and spacecraft designers visual images of the effects of the space environment on specific materials, systems and spacecraft in general. One can visually see the degradation of thermal blankets, meteoroid craters, outgassing discoloration, atomic oxygen erosion, etc.

Model of spacecraft atomic oxygen and solar exposure microenvironments

NASA Technical Reports Server (NTRS)

Bourassa, R. J.; Pippin, H. G.

1993-01-01

Computer models of environmental conditions in Earth orbit are needed for the following reasons: (1) derivation of material performance parameters from orbital test data, (2) evaluation of spacecraft hardware designs, (3) prediction of material service life, and (4) scheduling spacecraft maintenance. To meet these needs, Boeing has developed programs for modeling atomic oxygen (AO) and solar radiation exposures. The model allows determination of AO and solar ultraviolet (UV) radiation exposures for spacecraft surfaces (1) in arbitrary orientations with respect to the direction of spacecraft motion, (2) overall ranges of solar conditions, and (3) for any mission duration. The models have been successfully applied to prediction of experiment environments on the Long Duration Exposure Facility (LDEF) and for analysis of selected hardware designs for deployment on other spacecraft. The work on these models has been reported at previous LDEF conferences. Since publication of these reports, a revision has been made to the AO calculation for LDEF, and further work has been done on the microenvironments model for solar exposure.

Space Shuttle inflatable training articles

NASA Technical Reports Server (NTRS)

West, M. L.

1984-01-01

The design, development, construction, and testing of the Long Duration Exposure Facility inflatable and the space telescope training articles are discussed. While these articles are of similar nature, materials, and construction, they vary in size and present different problems with regards to size, shape, gross/net lift, and balance.

Selected results for LDEF thermal control coatings

NASA Technical Reports Server (NTRS)

Golden, Johnny L.

1993-01-01

Several different thermal control coatings were analyzed as part of the Long Duration Exposure Facility (LDEF) Materials Special Investigation Group activity and as part of the Space Environment Effects on Spacecraft Materials Experiment M0003. A brief discussion of the results obtained for these materials is presented.

Summary of materials and hardware performance on LDEF

NASA Technical Reports Server (NTRS)

Dursch, Harry; Pippin, Gary; Teichman, Lou

1993-01-01

A wide variety of materials and experiment support hardware were flown on the Long Duration Exposure Facility (LDEF). Postflight testing has determined the effects of the almost 6 years of low-earth orbit (LEO) exposure on this hardware. An overview of the results are presented. Hardware discussed includes adhesives, fasteners, lubricants, data storage systems, solar cells, seals, and the LDEF structure. Lessons learned from the testing and analysis of LDEF hardware is also presented.

Total Dose Effects (TDE) of heavy ionizing radiation in fungus spores and plant seeds: Preliminary investigations

NASA Technical Reports Server (NTRS)

Kranz, A. R.; Zimmermann, M. W.; Stadler, R.; Gartenbach, K. E.; Pickert, M.

1992-01-01

The opportunity to compare cosmic radiation effects caused during long and short duration exposure flights in biological objects are limited until now, and data obtained so far are very rare and insufficient. Because of the very long exposure of the experiment during the Long Duration Exposure Facility (LDEF) mission (approximately 2000 days) structural changes of the hardware material can be expected which will influence its biocompatibility and, thus, will interact with the radiobiological effects. The aim of the experiment flown on LDEF was a detailed investigation of biological effects caused by cosmic radiation especially of particles of high atomic number Z and high energy. The flight hardware consisted of standard BIOSTACK containers; in these containers a special sandwich construction consisted of visual plastic detectors with seed rsp. spore layers interlocked.

Analysis of systems hardware flown on LDEF: New findings and comparison to other retrieved spacecraft hardware

NASA Technical Reports Server (NTRS)

Dursch, Harry; Bohnhoff-Hlavacek, Gail; Blue, Donald; Hansen, Patricia

1995-01-01

The Long Duration Exposure Facility (LDEF) was retrieved in 1990 after spending 69 months in low-earth-orbit (LEO). A wide variety of mechanical, electrical, thermal, and optical systems, subsystems, and components were flown on LDEF. The Systems Special Investigation Group (Systems SIG) was formed by NASA to investigate the effects of the 69 month exposure on systems related hardware and to coordinate and collate all systems analysis of LDEF hardware. This report is the Systems SIG final report which updates earlier findings and compares LDEF systems findings to results from other retrieved spacecraft hardware such as Hubble Space Telescope. Also included are sections titled (1) Effects of Long Duration Space Exposure on Optical Scatter, (2) Contamination Survey of LDEF, and (3) Degradation of Optical Materials in Space.

Analysis of systems hardware flown on LDEF: New findings and comparison to other retrieved spacecraft hardware

NASA Astrophysics Data System (ADS)

Dursch, Harry; Bohnhoff-Hlavacek, Gail; Blue, Donald; Hansen, Patricia

1995-09-01

The Long Duration Exposure Facility (LDEF) was retrieved in 1990 after spending 69 months in low-earth-orbit (LEO). A wide variety of mechanical, electrical, thermal, and optical systems, subsystems, and components were flown on LDEF. The Systems Special Investigation Group (Systems SIG) was formed by NASA to investigate the effects of the 69 month exposure on systems related hardware and to coordinate and collate all systems analysis of LDEF hardware. This report is the Systems SIG final report which updates earlier findings and compares LDEF systems findings to results from other retrieved spacecraft hardware such as Hubble Space Telescope. Also included are sections titled (1) Effects of Long Duration Space Exposure on Optical Scatter, (2) Contamination Survey of LDEF, and (3) Degradation of Optical Materials in Space.

The performance of thermal control coatings on LDEF and implications to future spacecraft

NASA Technical Reports Server (NTRS)

Wilkes, Donald R.; Miller, Edgar R.; Mell, Richard J.; Lemaster, Paul S.; Zwiener, James M.

1993-01-01

The stability of thermal control coatings over the lifetime of a satellite or space platform is crucial to the success of the mission. With the increasing size, complexity, and duration of future missions, the stability of these materials becomes even more important. The Long Duration Exposure Facility (LDEF) offered an excellent testbed to study the stability and interaction of thermal control coatings in the low-Earth orbit (LEO) space environment. Several experiments on LDEF exposed thermal control coatings to the space environment. This paper provides an overview of the different materials flown and their stability during the extended LDEF mission. The exposure conditions, exposure environment, and measurements of materials properties (both in-space and postflight) are described. The relevance of the results and the implications to the design and operation of future space vehicles are also discussed.

Atomic oxygen exposure of LDEF experiment trays

NASA Technical Reports Server (NTRS)

Bourassa, R. J.; Gillis, J. R.

1992-01-01

Atomic oxygen exposures were determined analytically for rows, longerons, and end bays of the Long Duration Exposure Facility (LDEF). The calculations are based on an analytical model that accounts for the effects of thermal molecular velocity, atmospheric temperature, number density, spacecraft velocity, incidence angle, and atmospheric rotation on atomic oxygen flux. Results incorporate variations in solar activity, geomagnetic index, and orbital parameters occurring over the 6-year flight of the spacecraft. To facilitate use of the data, both detailed tabulations and summary charts for atomic oxygen fluences are presented.

Closeup of LDEF experiment trays documented during STS-32 photo survey

NASA Image and Video Library

1990-01-20

Closeup of Long Duration Exposure Facility (LDEF) experiment trays is documented during STS-32 retrieval activity and photo survey conducted by crewmembers onboard Columbia, Orbiter Vehicle (OV) 102. Partially visible is the Polymer Matrix Composite Materials Experiment. In the background is the surface of the Earth.

Seeds in space experiment results

NASA Technical Reports Server (NTRS)

Alston, Jim A.

1991-01-01

Two million seeds of 120 different varieties representing 106 species, 97 genera, and 55 plant families were flown aboard the Long Duration Exposure Facility (LDEF). The seeds were housed on the space exposed experiment developed for students (SEEDS) tray in sealed canister number six and in two small vented canisters. The tray was in the F-2 position. The seeds were germinated and the germination rates and development of the resulting plants compared to the control seed that stayed in Park Seed's seed storage facility. The initial results are presented. There was a better survival rate in the sealed canister in space than in the storage facility at Park Seed. At least some of the seeds in each of the vented canisters survived the exposure to vacuum for almost six years. The number of observed apparent mutations was very low.

Sixty-nine months in space: A history of the first LDEF (Long Duration Exposure Facility)

NASA Technical Reports Server (NTRS)

1990-01-01

The LDEF project is summarized from its conception, through its deployment, to the return of the experiments. A LDEF chronology and a fact sheet is included. The experiments carried more than 10,000 specimens to gather scientific data and to test the effects of long term space exposure on spacecraft materials, components, and systems. Results will be invaluable for the design of future spacecraft such as Space Station Freedom.

Practices of Unregulated Tanning Facilities in Missouri: Implications for Statewide Legislation

PubMed Central

Biesbroeck, Lauren K.; Lickerman, Stephanie H.; Cornelius, Lynn A.; Jeffe, Donna B.

2013-01-01

BACKGROUND: The incidence of skin cancer has increased in the United States, concomitant with increased UV radiation (UVR) exposure among young adults. We examined whether tanning facilities in Missouri, a state without indoor-tanning regulations, acted in accordance with the Food and Drug Administration’s recommendations and consistently imparted information to potential clients about the known risks of UVR. METHODS: We conducted a statewide telephone survey of randomly selected tanning facilities in Missouri. Each tanning facility was surveyed twice, in the morning (7 am–3 pm) and evening (3–10 pm), on different days, to determine intrasalon consistency of information provided to potential clients at different times. RESULTS: On average, 65% of 243 tanning-facility operators would allow children as young as 10 or 12 years old to use indoor-tanning devices, 80% claimed that indoor tanning would prevent future sunburns, and 43% claimed that there were no risks associated with indoor tanning. Intrasalon inconsistencies involved allowable age of use, and UVR exposure type and duration. Morning tanning-facility employees were more likely to allow consumers to start with maximum exposure times and UV-A–emitting devices (P < .001), whereas evening employees were more likely to allow 10- or 12-year-old children to use indoor-tanning devices (P = .008). CONCLUSIONS: Despite increasing evidence that UVR exposure in indoor-tanning devices is associated with skin cancer, ocular damage, and premature photoaging, tanning facilities in Missouri often misinformed consumers regarding these risks and lack of health benefits and inconsistently provided information about the Food and Drug Administration’s guidelines for tanning devices. PMID:23439910

The space shuttle payload planning working groups. Volume 10: Space technology

NASA Technical Reports Server (NTRS)

1973-01-01

The findings and recommendations of the Space Technology group of the space shuttle payload planning activity are presented. The elements of the space technology program are: (1) long duration exposure facility, (2) advanced technology laboratory, (3) physics and chemistry laboratory, (4) contamination experiments, and (5) laser information/data transmission technology. The space technology mission model is presented in tabular form. The proposed experiments to be conducted by each test facility are described. Recommended approaches for user community interfacing are included.

Third LDEF Post-Retrieval Symposium Abstracts

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Compiler)

1993-01-01

This volume is a compilation of abstracts submitted to the Third Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The abstracts represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science.

LDEF: 69 Months in Space. First Post-Retrieval Symposium, part 1

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1992-01-01

A compilation of papers from the symposium is presented. The papers represent the preliminary data analysis of the 57 experiments flown on the Long Duration Exposure Facility (LDEF). The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, and micrometeoroids), electronics, optics, and life sciences.

Outgassing and dimensional changes of polymer matrix composites in space

NASA Technical Reports Server (NTRS)

Tennyson, R. C.; Matthews, R.

1993-01-01

A thermal-vacuum outgassing model and test protocol for predicting outgassing times and dimensional changes for polymer matrix composites is described. Experimental results derived from a 'control' sample are used to provide the basis for analytical predictions to compare with the outgassing response of Long Duration Exposure Facility (LDEF) flight samples.

Holographic data storage crystals for the LDEF

NASA Technical Reports Server (NTRS)

Callen, W. Russell; Gaylord, Thomas K.

1993-01-01

Crystals of lithium niobate were passively exposed to the space environment of the Long Duration Exposure Facility (LDEF). Three of the four crystals contained volume holograms. Although the crystals suffered the surface damage characteristic of that suffered by other components on the Georgia Tech tray, the crystals remained suitable for the formation of volume holograms.

Analysis of impactor residues in tray clamps from the Long Duration Exposure Facility. Part 2: Clamps from Bay B of the satellite

NASA Technical Reports Server (NTRS)

Bernhard, Ronald P.; Zolensky, Michael E.

1994-01-01

The Long Duration Exposure Facility (LDEF) was placed in low-Earth orbit (LEO) in 1984 and recovered 5.7 years later. The LDEF was host to several individual experiments specifically designed to characterize critical aspects of meteoroid and debris environment in LEO. However, it was realized from the beginning that the most efficient use of the satellite would be to examine the entire surface for impact features. In this regard, particular interest centered on common exposed materials that faced in all LDEF pointing directions. Among the most important of these materials was the tray clamps. Therefore, in an effort to better understand the nature of particulates in LEO and their effects on spacecraft hardware, residues found in impact features on LDEF tray clamp surfaces are being analyzed. This catalog presents all data from clamps from Bay B of the LDEF. NASA Technical Memorandum 104759 has cataloged impacts that occurred on Bay B (published March 1993). Subsequent catalogs will include clamps from succeeding bays of the satellite.

Long Duration Exposure Facility (LDEF) optical systems SIG summary and database

NASA Astrophysics Data System (ADS)

Bohnhoff-Hlavacek, Gail

1992-09-01

The main objectives of the Long Duration Exposure Facility (LDEF) Optical Systems Special Investigative Group (SIG) Discipline are to develop a database of experimental findings on LDEF optical systems and elements hardware, and provide an optical system overview. Unlike the electrical and mechanical disciplines, the optics effort relies primarily on the testing of hardware at the various principal investigator's laboratories, since minimal testing of optical hardware was done at Boeing. This is because all space-exposed optics hardware are part of other individual experiments. At this time, all optical systems and elements testing by experiment investigator teams is not complete, and in some cases has hardly begun. Most experiment results to date, document observations and measurements that 'show what happened'. Still to come from many principal investigators is a critical analysis to explain 'why it happened' and future design implications. The original optical system related concerns and the lessons learned at a preliminary stage in the Optical Systems Investigations are summarized. The design of the Optical Experiments Database and how to acquire and use the database to review the LDEF results are described.

Long Duration Exposure Facility (LDEF) optical systems SIG summary and database

NASA Technical Reports Server (NTRS)

Bohnhoff-Hlavacek, Gail

1992-01-01

The main objectives of the Long Duration Exposure Facility (LDEF) Optical Systems Special Investigative Group (SIG) Discipline are to develop a database of experimental findings on LDEF optical systems and elements hardware, and provide an optical system overview. Unlike the electrical and mechanical disciplines, the optics effort relies primarily on the testing of hardware at the various principal investigator's laboratories, since minimal testing of optical hardware was done at Boeing. This is because all space-exposed optics hardware are part of other individual experiments. At this time, all optical systems and elements testing by experiment investigator teams is not complete, and in some cases has hardly begun. Most experiment results to date, document observations and measurements that 'show what happened'. Still to come from many principal investigators is a critical analysis to explain 'why it happened' and future design implications. The original optical system related concerns and the lessons learned at a preliminary stage in the Optical Systems Investigations are summarized. The design of the Optical Experiments Database and how to acquire and use the database to review the LDEF results are described.

Continued results of the seeds in space experiment

NASA Technical Reports Server (NTRS)

Alston, Jim A.

1992-01-01

Two million seeds of 120 different varieties representing 106 species, 97 genera, and 55 plant families were flown aboard the Long Duration Exposure Facility (LDEF). The seeds were housed on the Space Exposed Experiment Developed for Students (SEEDS) tray in the sealed canister number 6 and in two small vented canisters. The seeds were germinated and the germination rates and development of the resulting plants compared to the control seed that stayed in the storage facility. There was a better survival rate in the sealed canister in space than in the storage facility. At least some of the seed in the vented canisters survived the exposure to vacuum for almost six years. The number of observed mutations was very low. In the initial testing, the small seeded crops were not grown to maturity to check for mutation and obtain a second generation seed. These small seeded crops are now being grown for evaluation.

Characterization of selected LDEF polymer matrix resin composite materials

NASA Technical Reports Server (NTRS)

Young, Philip R.; Slemp, Wayne S.; Witte, William G., Jr.; Shen, James Y.

1991-01-01

The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composite materials which received 5 years and 10 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. Resin loss and a decrease in mechanical performance as well as dramatic visual effects were observed. However, chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymeric matrix had not changed significantly in response to this exposure. The potential effect of a silicon-containing molecular contamination of these specimens is addressed.

LDEF materials data analysis: Representative examples

NASA Technical Reports Server (NTRS)

Pippin, H. Gary; Crutcher, E. R.

1992-01-01

Results of measurements on silverized teflon, heat shrink tubing and nylon tie downs on the wire harness clamps, silvered hex nuts, and contamination deposits are presented. We interpret the results in terms of our microenvironments exposure model and locations on the Long Duration Exposure Facility (LDEF). Distinct changes in the surface properties of FEP were observed as a function of UV exposure. Significant differences in outgassing characteristics were detected for hardware on the interior row 3 relative to identical hardware on the interior row 3 relative to identical hardware on nearby rows. The implications for in service performance are reviewed.

LDEF mechanical systems

NASA Technical Reports Server (NTRS)

Spear, Steve; Dursch, Harry

1991-01-01

Following the Long Duration Exposure Facility (LDEF), the Systems Special Investigation Group (SIG) was involved in a considerable amount of testing of mechanical hardware flown on the LDEF. The primary objectives were to determine the effects of the long term exposure on: (1) mechanisms employed both on the LDEF or as part of individual experiments; (2) structural components; and (3) fasteners. Results of testing the following LDEF hardware are presented: LDEF structure, fasteners, trunnions, end support beam, environment exposure control cannisters, motors, and lubricants. A limited discussion of PI test results is included. The lessons learned are discussed along with the future activities of the System SIG.

Walk-through survey report, Gulfstream American Corporation (formerly Grumman-American Aviation Corp. ) Savannah, Georgia

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

Matanoski, G.; Billings, C.; Levine, M.

1979-05-01

The four major paint shops (light aircraft, small parts, Colar anticorrosive primer, and the Alodine epoxy/phenolic resin paint shop) employing 30 workers at Gulfstream American Corporation, Savannah, Georgia were the primary focus of a walk-through on July 12 and 13, 1978. The company's record-keeping system, medical program, and industrial-hygiene program were examined. The authors recommend that the light aircraft paint shop be included in an industrial hygiene study since the workload is fairly steady, types of paints and peripheral exposures are easily documented, and current control measures result in relatively low exposures of personnel to paint constituents. An epidemiological studymore » is not recommended because the facility is new and the number of painters and the duration of exposures are limited. The authors suggest that this factory be considered during the final selection of aircraft manufacturing facilities for medical studies because of the degree of potential exposure to polyurethane paint.« less

LDEF: 69 Months in Space. Part 4: Second Post-Retrieval Symposium

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1993-01-01

A compilation of papers presented at the Second Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium are presented. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life sciences.

LDEF: 69 Months in Space. Part 1: Second Post-Retrieval Symposium

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1993-01-01

A compilation of papers presented at the Second Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium is included. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life sciences.

Surface Analysis of LDEF Materials

NASA Technical Reports Server (NTRS)

Wightman, J. P. (Principal Investigator)

1996-01-01

The abstract to the M.S. thesis included as appendix to this report contains the details of the research performed under this grant. Presentations and publications resulting from the research are listed as the main content of the report itself. The thesis describes the surface characterization procedures and analysis of materials flown in the NASA Long Duration Exposure Facility (LDEF).

LDEF: 69 Months in Space. Part 3: Second Post-Retrieval Symposium

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1993-01-01

Papers presented at the Second Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium are included. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science.

Immune response of laying hens exposed to 30 ppm ammonia for 25 weeks

USDA-ARS?s Scientific Manuscript database

Ammonia is one of the most prominent aerial pollutants inside poultry production facilities, affecting chicken health and well-being based on its levels and exposure durations. The aim of this study was to investigate the effect of 30 ppm ammonia on the immune response of laying hens. Hens at 18 wk ...

Chemical characterization of selected LDEF polymeric materials

NASA Technical Reports Server (NTRS)

Young, Philip R.; Slemp, Wayne S.

1991-01-01

Chemical characterization of selected polymeric materials which received exposure on the Long Duration Exposure Facility (LDEF) is reported. The specimens examined include silvered fluorinated ethylene propylene Teflon thermal blanket material, polysulfone, epoxy, polyimide matrix resin/graphite fiber reinforced composites, and several high performance polymer films. These specimens came from numerous LDEF locations, and thus received different environmental exposures. The results to date show no significant change at the molecular level in the polymer that survived exposure. Scanning electron and scanning tunneling microscopes show resin loss and a texturing of some specimens which resulted in a change in optical properties. The potential effect of a silicon-containing molecular contamination on these materials is addressed. The possibility of continued post-exposure degradation of some polymeric films is also proposed.

Effects of LDEF flight exposure on selected polymer matrix resin composite materials

NASA Technical Reports Server (NTRS)

Slemp, Wayne S.; Young, Philip R.; Witte, William G., Jr.; Shen, James Y.

1992-01-01

The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composites materials which received over five years and nine months of exposure to the low earth orbit (LEO) environment in experiment AO134 on the Long Duration Exposure Facility is reported. The changes in mechanical properties of ultimate tensile strength and tensile modulus for exposed flight specimens are compared to the three sets of control specimens. Marked changes in surface appearance are discussed, and resin loss is reported. The chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymetric matrix had not changed significantly in response to this exposure.

Statistical modelling of formaldehyde occupational exposure levels in French industries, 1986-2003.

PubMed

Lavoué, Jérôme; Vincent, Raymond; Gérin, Michel

2006-04-01

Occupational exposure databanks (OEDBs) have been cited as sources of exposure data for exposure surveillance and exposure assessment in epidemiology. In 2003, an extract was made from COLCHIC, the French national OEDB, of all concentrations of formaldehyde. The data were analysed with extended linear mixed-effects models in order to identify influent variables and elaborate a multi-sector picture of formaldehyde exposures. Respectively, 1401 and 1448 personal and area concentrations were available for the analysis. The fixed effects of the personal and area models explained, respectively, 57 and 53% of the total variance. Personal concentrations were related to the sampling duration (short-term higher than TWA levels), decreased with the year of sampling (-9% per year) and were higher when local exhaust ventilation was present. Personal levels taken during planned visits and for occupational illness notification purpose were consistently lower than those taken during ventilation modification programmes or because the hygienist suspected the presence of significant risk or exposure. Area concentrations were related to the sampling duration (short-term higher than TWA levels), and decreased with the year of sampling (-7% per year) and when the measurement sampling flow increased. Significant within-facility (correlation coefficient 0.4-0.5) and within-sampling campaign correlation (correlation coefficient 0.8) was found for both area and personal data. The industry/task classification appeared to have the greatest influence on exposure variability while the sample duration and the sampling flow were significant in some cases. Estimates made from the models for year 2002 showed elevated formaldehyde exposure in the fields of anatomopathological and biological analyses, operation of gluing machinery in the wood industry, operation and monitoring of mixers in the pharmaceutical industry, and garages and warehouses in urban transit authorities.

Elaborated Odor Test for Extended Exposure

NASA Technical Reports Server (NTRS)

Buchanan, Vanessa D.; Henry, Emily J.; Mast, Dion J.; Harper, Susana A.; Beeson, Harold D.; Tapia, Alma S.

2016-01-01

Concerns were raised when incidental exposure to a proprietary bonding material revealed the material had an irritating odor. The NASA-STD-6001B document describes a supplemental test method option for programs to evaluate materials with odor concerns (Test 6, Odor Assessment). In addition to the supplemental standard odor assessment with less than 10 seconds of exposure, the NASA White Sands Test Facility (WSTF) Materials Flight Acceptance Testing section was requested to perform an odor test with an extended duration to evaluate effects of an extended exposure and to more closely simulate realistic exposure scenarios. With approval from the NASA Johnson Space Center Industrial Hygienist, WSTF developed a 15-minute odor test method. WSTF performed this extended-duration odor test to evaluate the odor and physical effects of the bonding material configured between two aluminum plates, after the safety of the gas was verified via toxicity analysis per NASA-STD-6001B Test 7, Determination of Offgassed Products. During extended-duration testing, odor panel members were arranged near the test material in a small room with the air handlers and doors closed to minimize dilution. The odor panel members wafted gas toward themselves and recorded their individual assessments of odor and physical effects at various intervals during the 15-minute exposure and posttest. A posttest interview was conducted to obtain further information. Testing was effective in providing data for comparison and selection of an optimal offgassing and odor containment configuration. The developed test method for extended exposure is proposed as a useful tool for further evaluating materials with identified odors of concern if continued use of the material is anticipated.

Surveillance of hearing loss among older construction and trade workers at Department of Energy nuclear sites.

PubMed

Dement, John; Ringen, Knut; Welch, Laura; Bingham, Eula; Quinn, Patricia

2005-11-01

Medical screening programs at three Departments of Energy (DOE) nuclear weapons facilities (Hanford Nuclear Reservation, Oak Ridge, and the Savannah River Site) have included audiometric testing since approximately 1996. This report summarizes hearing evaluations through March 31, 2003. Occupational examinations included a medical history, limited physical examination, and tests for medical effects from specific hazards, including audiometric testing. Hearing thresholds by frequency for DOE workers were compared to age-standardized thresholds among an external comparison population of industrial workers with noise exposures <80 dBA. Multivariate analyses were used to explore the risk of hearing impairment by duration of construction trade work and self-reported noise exposure, while controlling for potential confounders such as age, race, sex, smoking, elevated serum cholesterol, hypertension, solvent exposures, and recreational noise exposures. Hearing thresholds among DOE workers were much higher than observed in a comparison population of industrial workers with low noise exposures. Overall, 59.7% of workers examined were found to have material hearing impairment by NIOSH criteria. Age, duration of construction work, smoking, and self-reported noise exposure increased the risk of hearing loss. The risk of material hearing impairment was significantly elevated for construction trade workers compared to the external comparison population (odds-ratio = 1.6, 95% CI = 1.3-2.1) and increased with the duration of trade work. These medical screening programs confirm worker concerns about risks for hearing loss and the need for hearing conservation programs for construction workers, with emphasis on the prevention of noise exposures.

Retrievable payload carrier, next generation Long Duration Exposure Facility: Update 1992

NASA Technical Reports Server (NTRS)

Perry, A. T.; Cagle, J. A.; Newman, S. C.

1993-01-01

Access to space and cost have been two major inhibitors of low Earth orbit research. The Retrievable Payload Carrier (RPC) Program is a commercial space program which strives to overcome these two barriers to space experimentation. The RPC Program's fleet of spacecraft, ground communications station, payload processing facility, and experienced integration and operations team will provide a convenient 'one-stop shop' for investigators seeking to use the unique vantage point and environment of low Earth orbit for research. The RPC is a regularly launched and retrieved, free-flying spacecraft providing resources adequate to meet modest payload/experiment requirements, and presenting ample surface area, volume, mass, and growth capacity for investigator usage. Enhanced capabilities of ground communications, solar-array-supplied electrical power, central computing, and on-board data storage pick up on the path where NASA's Long Duration Exposure Facility (LDEF) blazed the original technology trail. Mission lengths of 6-18 months, or longer, are envisioned. The year 1992 was designated as the 'International Space Year' and coincides with the 500th anniversary of Christopher Columbus's voyage to the New World. This is a fitting year in which to launch the full scale development of our unique shop of discovery whose intent is to facilitate retrieving technological rewards from another new world: space. Presented is an update on progress made on the RPC Program's development since the November 1991 LDEF Materials Workshop.

Results of the examination of LDEF polyurethane thermal control coatings

NASA Technical Reports Server (NTRS)

Golden, Johnny L.

1994-01-01

This report summarizes the condition of polyurethane thermal control coatings subjected to 69 months of low earth orbit (LEO) exposure on the Long Duration Exposure Facility (LDEF) mission. Specimens representing all environmental aspects obtainable by LDEF were analyzed. Widely varying changes in the thermo-optical and mechanical properties of these materials were observed, depending on atomic oxygen and ultraviolet radiation fluences. High atomic oxygen fluences, regardless of ultraviolet radiation exposure levels, resulted in near original optical properties for these coatings but with a degradation in their mechanical condition. A trend in solar absorptance increase with ultraviolet radiation fluence was observed. Contamination, though observed, exhibited minimal effects.

An analysis of LDEF-exposed silvered FEP teflon thermal blanket material

NASA Technical Reports Server (NTRS)

Young, Philip R.; Slemp, Wayne S.

1991-01-01

The characterization of selected silvered fluorinated ethylene propylene (FEP) teflon thermal blanket material which received 5 years and 9 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. X-ray photoelectron spectroscopy, infrared, and thermal analyses did not detect a significant change at the molecular level as the result of this exposure. However, various microscopic analyses revealed a roughening of the coating surface due to atomic oxygen erosion which resulted in some materials changing from specular reflectors of visible radiation to diffuse reflectors. The potential effect of silicon-containing molecular contamination on these materials is addressed.

A technique for synergistic atomic oxygen and vacuum ultraviolet radiation durability evaluation of materials for use in LEO

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Banks, Bruce A.

1996-01-01

Material erosion data collected during flight experiments such as the Environmental Oxygen Interaction with Materials (EOIM)-3 and the Long Duration Exposure Facility (LDEF) have raised questions as to the sensitivity of material erosion to levels of atomic oxygen exposure and vacuum ultraviolet (VUV) radiation. The erosion sensitivity of some materials such as FEP Teflon used as a thermal control material on satellites in low Earth orbit (LEO), is particularly important but difficult to determine. This is in large part due to the inability to hold all but one exposure parameter constant during a flight experiment. This is also difficult to perform in a ground based facility, because often the variation of the level of atomic oxygen or VUV radiation also results in a change in the level of the other parameter. A facility has been developed which allows each parameter to be changed almost independently and offer broad area exposure. The resulting samples can be made large enough for mechanical testing. The facility uses an electron cyclotron resonance plasma source to provide the atomic oxygen. A series of glass plates is used to focus the atomic oxygen while filtering the VUV radiation from the plasma source. After filtering, atomic oxygen effective flux levels can still be measured which are as high as 7 x 10(exp 15) atoms/cm(exp 2)-sec which is adequate for accelerated testing. VUV radiation levels after filtering can be as low as 0.3 suns. Additional VUV suns can be added with the use of deuterium lamps which allow the VUV level to be changed while keeping the flux of atomic oxygen constant. This paper discusses the facility, and results from exposure of Kapton and FEP at pre-determined atomic oxygen flux and VUV sun levels.

Ballistocraft: a novel facility for microgravity research.

PubMed

Mesland, D; Paris, D; Huijser, R; Lammertse, P; Postema, R

1995-05-01

One of ESA's aims is to provide the microgravity research community with various microgravity exposure facilities. Those facilities include drop towers, sounding rockets, and parabolic flights on board aircraft, in addition to orbital spacecraft. Microgravity flights are usually achieved using large aircraft like the French 'Caravelle' that offer a large payload volume and where a person can be present to perform the experiments and to participate as a human test-subject. However, the microgravity community is also very interested in a flexible, complementary facility that would allow frequent and repetitive exposure to microgravity for a laboratory-type of payload. ESA has therefore undertaken a study of the potential of using a 'ballistocraft', a small unmanned aircraft, to provide a low-cost facility for short-duration (30-40 seconds) microgravity experimentation. Fokker Space & Systems performed the study under an ESA contract, supported by Dutch national funding. To assess the ballistocraft, a simple breadboard of the facility was built and flight tests were performed. The ability of the on-board controller to achieve automated parabolic flights was demonstrated, and the performance of the controller in one-g level flights, and in flights with both zero-g and partial-g setpoints, was evaluated. The partial-g flights are a unique and valuable feature of the facility.

Low Earth orbital atomic oxygen environmental simulation facility for space materials evaluation

NASA Technical Reports Server (NTRS)

Stidham, Curtis R.; Banks, Bruce A.; Stueber, Thomas J.; Dever, Joyce A.; Rutledge, Sharon K.; Bruckner, Eric J.

1993-01-01

Simulation of low Earth orbit atomic oxygen for accelerated exposure in ground-based facilities is necessary for the durability evaluation of space power system component materials for Space Station Freedom (SSF) and future missions. A facility developed at the National Aeronautics and Space Administrations's (NASA) Lewis Research Center provides accelerated rates of exposure to a directed or scattered oxygen beam, vacuum ultraviolet (VUV) radiation, and offers in-situ optical characterization. The facility utilizes an electron-cyclotron resonance (ECR) plasma source to generate a low energy oxygen beam. Total hemispherical spectral reflectance of samples can be measured in situ over the wavelength range of 250 to 2500 nm. Deuterium lamps provide VUV radiation intensity levels in the 115 to 200 nm range of three to five equivalent suns. Retarding potential analyses show distributed ion energies below 30 electron volts (eV) for the operating conditions most suited for high flux, low energy testing. Peak ion energies are below the sputter threshold energy (approximately 30 eV) of the protective coatings on polymers that are evaluated in the facility, thus allowing long duration exposure without sputter erosion. Neutral species are expected to be at thermal energies of approximately .04 eV to .1 eV. The maximum effective flux level based on polyimide Kapton mass loss is 4.4 x 10 exp 6 atoms/((sq. cm)*s), thus providing a highly accelerated testing capability.

Elastic modulus measurements of LDEF glasses and glass-ceramics using a speckle technique

NASA Technical Reports Server (NTRS)

Wiedlocher, D. E.; Kinser, D. L.

1992-01-01

Elastic moduli of five glass types and the glass-ceramic Zerodur, exposed to a near-earth orbit environment on the Long Duration Exposure Facility (LDEF), were compared to that of unexposed samples. A double exposure speckle photography technique utilizing 633 nm laser light was used in the production of the speckle pattern. Subsequent illumination of a double exposed negative using the same wavelength radiation produces Young's fringes from which the in-plane displacements are measured. Stresses imposed by compressive loading produced measurable strains in the glasses and glass-ceramic.

Development and application of a 3-D geometry/mass model for LDEF satellite ionizing radiation assessments

NASA Technical Reports Server (NTRS)

Colborn, B. L.; Armstong, T. W.

1993-01-01

A three-dimensional geometry and mass model of the Long Duration Exposure Facility (LDEF) spacecraft and experiment trays was developed for use in predictions and data interpretation related to ionizing radiation measurements. The modeling approach, level of detail incorporated, example models for specific experiments and radiation dosimeters, and example applications of the model are described.

Composite materials flown on the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

George, Pete E.; Dursch, Harry W.; Pippin, H. Gary

1995-01-01

Organic composite test specimens were flown on several LDEF experiments. Both bare and coated composites were flown. Atomic oxygen eroded bare composite material, with the resins being recessed at a greater rate than the fibers. Selected coating techniques protected the composite substrate in each case. Tensile and optical properties are reported for numerous specimens. Fiberglass and metal matrix composites were also flown.

Long Duration Exposure Facility

DTIC Science & Technology

1988-06-30

Blue and Oxazine Dyes- Name Absorption -mazimu= Lasing Wavelengths un. un. (solvent) (solvent) Nile Blue A, 635 690 Perchlorate (ethanol) (ethanol...Fluence(/cm Etching 5 Al 3.5 MeV 5x10 6 N NaOH 6 o BI8 PrQtons Ixl0 50 C, 15 hr. 6 C9 (normal 3x10 (2 sided) incidence) 01 (unirradiated) 5 DIS 2.0

LDEF: 69 Months in Space. Second Post-Retrieval Symposium, part 2

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1993-01-01

This document is a compilation of papers presented at the Second Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science.

LDEF: 69 Months in Space. First Post-Retrieval Symposium, part 3

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1992-01-01

A compilation of papers presented at the First Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium is presented. The papers represent the preliminary data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, and micrometeoroid), electronics, optics, and life sciences.

Optical characterization of contaminant film. [long duration exposure facility

NASA Technical Reports Server (NTRS)

Blakkolb, Brian K.; Yaung, James Y.; Kosic, Tom; Bowen, Howard

1992-01-01

The so called 'nicotine stain' documented at many locations on the Long Duration Exposure Facility is still unexplained as to the exact origin and mechanism of deposition, although enough is known to have some understanding of the conditions coincident for the formation of the deposits. Direct and scattered atomic oxygen flux, and solar ultraviolet radiation interacting with materials outgassing products have all been implicated in the formation of the dark brown contamination deposits. The nicotine stain represents a potential of performance degradation for spacecraft designed for long term operation in low Earth orbit and therefore, a need exists to characterize this form of spacecraft self contamination and quantify the impact on thermal/optical systems. Optical property measurements in the spectral range of 2 to 10 microns were performed on specimens of the contaminated film. Reflectance measurements of the contaminant film as deposited on the surface and as free standing films are presented along with transmission spectra for the bulk material. Thickness measurements along with micrographic examination of the cross section of the deposit reveal the layered structure of the deposit which further implicates solar illumination as a factor in the deposition mechanism.

Current activities and results of the Long Duration Exposure Facility Meteoroid and Debris Special Investigation Group

NASA Astrophysics Data System (ADS)

See, Thomas H.; Leago, Kimberly S.; Warren, Jack L.; Bernhard, Ronald P.; Zolensky, Michael E.

1994-03-01

Fiscal Year 1994 will bring to a close the initial investigative activities associated with the Long Duration Exposure Facility (LDEF). LDEF was a 14-faced spacecraft (i.e., 12-sided cylinder and two ends) which housed 54 different experimental packages in low-Earth orbit (LEO) from Apr. 1984 to Jan. 1990 (i.e., for approx. 5.75 years). Since LDEF's return, the Meteoroid & Debris Special Investigation Group (M&D SIG) has been examining various LDEF components in order to better understand and define the LEO particulate environment. Members of the M&D SIG at JSC in Houston, TX have been contributing to these studies by carefully examining and documenting all impact events found on LDEF's 6061-T6 aluminum Intercostals (i.e., one of the spacecraft's structural frame components). Unlike all other hardware on LDEF, the frame exposed significantly large surface areas of a single homogeneous material in all (i.e., 26) possible LDEF pointing directions. To date, 28 of the 68 Intercostals in the possession of the M&D SIG have been documented. This data, as well as similar information from various LDEF investigators, can be accessed through the M&D SIG Database which is maintained at JSC.

Current activities and results of the Long Duration Exposure Facility Meteoroid and Debris Special Investigation Group

NASA Technical Reports Server (NTRS)

See, Thomas H.; Leago, Kimberly S.; Warren, Jack L.; Bernhard, Ronald P.; Zolensky, Michael E.

1994-01-01

Fiscal Year 1994 will bring to a close the initial investigative activities associated with the Long Duration Exposure Facility (LDEF). LDEF was a 14-faced spacecraft (i.e., 12-sided cylinder and two ends) which housed 54 different experimental packages in low-Earth orbit (LEO) from Apr. 1984 to Jan. 1990 (i.e., for approx. 5.75 years). Since LDEF's return, the Meteoroid & Debris Special Investigation Group (M&D SIG) has been examining various LDEF components in order to better understand and define the LEO particulate environment. Members of the M&D SIG at JSC in Houston, TX have been contributing to these studies by carefully examining and documenting all impact events found on LDEF's 6061-T6 aluminum Intercostals (i.e., one of the spacecraft's structural frame components). Unlike all other hardware on LDEF, the frame exposed significantly large surface areas of a single homogeneous material in all (i.e., 26) possible LDEF pointing directions. To date, 28 of the 68 Intercostals in the possession of the M&D SIG have been documented. This data, as well as similar information from various LDEF investigators, can be accessed through the M&D SIG Database which is maintained at JSC.

Long duration exposure facility post-flight thermal analysis, part 1

NASA Technical Reports Server (NTRS)

Berrios, William M.; Sampair, Thomas R.

1992-01-01

Results of the post-flight thermal analysis of the Long Duration Exposure Facility (LDEF) mission are presented. The LDEF mission thermal analysis was verified by comparing the thermal model results to flight data from the LDEF Thermal Measurements System (THERM). Post-flight calculated temperature uncertainties have been reduced to under +/- 18 F from the pre-flight uncertainties of +/- 40 F. The THERM consisted of eight temperature sensors, a shared tape recorder, a standard LDEF flight battery, and an electronics control box. The temperatures were measured at selected locations on the LDEF structure interior during the first 390 days of flight and recorded for post-flight analysis. After the LDEF retrieval from Space on 12 Jan. 1990, the tape recorder was recovered from the spacecraft and the data reduced for comparison to the LDEF predicted temperatures. The LDEF mission temperatures were calculated prior to the LDEF deployment on 7 Apr. 1980, and updated after the LDEF retrieval with the following actual flight parameter data: including thermal fluxes, spacecraft attitudes, thermal coatings degradation, and contamination effects. All updated data used for the calculation of post-flight temperatures is also presented in this document.

The LDEF ultra heavy cosmic ray experiment

NASA Technical Reports Server (NTRS)

Osullivan, D.; Thompson, A.; Bosch, J.; Keegan, R.; Wenzel, K.-P.; Smit, A.; Domingo, C.

1991-01-01

The Long Duration Exposure Facility (LDEF) Ultra Heavy Cosmic Ray Experiment (UHCRE) used 16 side viewing LDEF trays giving a total geometry factor for high energy cosmic rays of 30 sq m sr. The total exposure factor was 170 sq m sr y. The experiment is based on a modular array of 192 solid state nuclear track detector stacks, mounted in sets of 4 pressure vessels (3 experiment tray). The extended duration of the LDEF mission has resulted in a greatly enhanced potential scientific yield from the UHCRE. Initial scanning results indicate that at least 2000 cosmic ray nuclei with Z greater than 65 were collected, including the world's first statistically significant sample of actinides. Postflight work to date and the current status of the experiment are reviewed. Provisional results from analysis of preflight and postflight calibrations are presented.

Effects of long duration exposure to simulated space environment on nonmetallic materials properties

NASA Technical Reports Server (NTRS)

Peacock, C. L., Jr.; Whitaker, A. F.

1983-01-01

Nonmetallic materials specimens from the Viking program were tested in situ invacuo after continuous thermal vacuum exposure from 1971/1972 to the present. Eleven tests were done on appropriate specimens of 30 materials; however, no single material received all the tests. Some specimens also were exposed to 1 or 2.5 MeV electrons at differing fluences before testing. Baseline exposure data is reported for graphite/epoxy specimens that were exposed to vacuum since 1974. These materials were transferred to the thermal vacuum storage facility for future in situ testing and irradiation. Thin G/E specimens were tensile tested after thermal-vacuum cycling exposure. Photomicrographic examinations and SEM analyses were done on the failed specimens.

Multilayer Insulation Material Guidelines

NASA Technical Reports Server (NTRS)

Finckenor, M. M.; Dooling, D.

1999-01-01

Multilayer Insulation Material Guidelines provides data on multilayer insulation materials used by previous spacecraft such as Spacelab and the Long-Duration Exposure Facility and outlines other concerns. The data presented in the document are presented for information only. They can be used as guidelines for multilayer insulation design for future spacecraft provided the thermal requirements of each new design and the environmental effects on these materials are taken into account.

Mechanisms flown on LDEF

NASA Technical Reports Server (NTRS)

Dursch, Harry; Spear, Steve

1992-01-01

A wide variety of mechanisms were flown on the Long Duration Exposure Facility (LDEF). These include canisters, valves, gears, drive train assemblies, and motors. This report will provide the status of the Systems SIG effort into documenting, integrating, and developing 'lessons learned' for the variety of mechanisms flown on the LDEF. Results will include both testing data developed by the various experimenters and data acquired by testing of hardware at Boeing.

The LDEF benefits. [planned experiments

NASA Technical Reports Server (NTRS)

Kinard, W. H.

1982-01-01

The Long Duration Exposure Facility (LDEF) is described, and experiments planned for the first LDEF mission are discussed. Four of the eight involve scientific studies of interstellar gas, micrometeoroids, cosmic rays, and crystal growth in zero gravity, and four involve technology studies of the space environmental effects on solar cells, composite materials, thermal coatings, fiber optics, and electronic instruments. For each experiment, the objectives and methods are discussed.

Hyperthermal Environments Simulator for Nuclear Rocket Engine Development

NASA Technical Reports Server (NTRS)

Litchford, Ron J.; Foote, John P.; Clifton, W. B.; Hickman, Robert R.; Wang, Ten-See; Dobson, Christopher C.

2011-01-01

An arc-heater driven hyperthermal convective environments simulator was recently developed and commissioned for long duration hot hydrogen exposure of nuclear thermal rocket materials. This newly established non-nuclear testing capability uses a high-power, multi-gas, wall-stabilized constricted arc-heater to produce hightemperature pressurized hydrogen flows representative of nuclear reactor core environments, excepting radiation effects, and is intended to serve as a low-cost facility for supporting non-nuclear developmental testing of hightemperature fissile fuels and structural materials. The resulting reactor environments simulator represents a valuable addition to the available inventory of non-nuclear test facilities and is uniquely capable of investigating and characterizing candidate fuel/structural materials, improving associated processing/fabrication techniques, and simulating reactor thermal hydraulics. This paper summarizes facility design and engineering development efforts and reports baseline operational characteristics as determined from a series of performance mapping and long duration capability demonstration tests. Potential follow-on developmental strategies are also suggested in view of the technical and policy challenges ahead. Keywords: Nuclear Rocket Engine, Reactor Environments, Non-Nuclear Testing, Fissile Fuel Development.

Effect of space exposure on pyroelectric infrared detectors

NASA Technical Reports Server (NTRS)

Robertson, James B.; Clark, Ivan O.

1991-01-01

Twenty pyroelectric type infrared detectors were flown onboard the Long Duration Exposure Facility (LDEF). The detector chips were of three different pyroelectric materials: lithium-tantalate, strontium-barium-niobate, and triglycine-sulfide. The experiment was passive; no measurements were taken during the flight. Performance of the detectors was measured before and after flight. Postflight measurements revealed that detectors made of lithium-tantalate and strontium-barium-niobate suffered no measureable loss in performance. Detectors made of triglycine-sulfide suffered complete loss of performance, but so did the control samples of the same material. Repoling of the triglycine-sulfide failed to revive the detectors.

Induced radioactivity in LDEF components

NASA Technical Reports Server (NTRS)

Harmon, B. A.; Fishman, G. J.; Parnell, T. A.; Laird, C. E.

1992-01-01

A systematic study of the induced radioactivity of the Long Duration Exposure Facility (LDEF) is being carried out in order to gather information about the low earth orbit radiation environment and its effects on materials. The large mass of the LDEF spacecraft, its stabilized configuration, and long mission duration have presented an opportunity to determine space radiation-induced radioactivities with a precision not possible before. Data presented include preliminary activities for steel and aluminum structural samples, and activation subexperiment foils. Effects seen in the data show a clear indication of the trapped proton anisotropy in the South Atlantic Anomaly and suggest contributions from different sources of external radiation fluxes.

American association of poison control centers database characterization of human tilmicosin exposures, 2001-2005.

PubMed

Oakes, Jennifer; Seifert, Steven

2008-12-01

Tilmicosin is a veterinary antibiotic with significant human toxicity at doses commonly used in animals, but the parenteral dose-response relationship has not been well characterized. Human exposures to tilmicosin in the database of the American Association of Poison Control Centers (AAPCC) from 2001 to 2005 were analyzed for demographic associations, exposure dose, clinical effects and outcomes. Over the 5-year period, there were 1,291 single-substance human exposures to tilmicosin. The mean age was 39.1 years, and 80% were male. By route there were 768 (54%) parenteral exposures. Patients with parenteral exposures had a significantly increased likelihood of being seen at a healthcare facility, admission, and admission to an ICU. With nonparenteral exposure, most had no clinical effects or minor effects, and there were no major effects or deaths. With parenteral exposure, moderate effects occurred in 46 (6%), major effects in 2 (0.3%) and there were 4 (0.5%) deaths, two of which were suicides. A dose-response relationship could be demonstrated. Clinical effect durations of up to a week occurred at even the lowest dose range. Over 250 cases of human tilmicosin exposure are reported to poison centers per year and over 150 of those are parenteral. Most exposures produce no or minor effects, but fatalities have occurred with parenteral exposure. The case fatality rate in parenteral exposures is 10 times the case fatality rate for all human exposures in the AAPCC database. Significant adverse and prolonged effects are reported at parenteral doses > 0.5 mL, suggesting that all parenteral exposures should be referred for healthcare facility evaluation.

Meteoroid and Debris Impact Features Documented on the Long Duration Exposure Facility

DTIC Science & Technology

1990-08-01

surfaces was very different from the hole production (penetration) mechanism in true thin films; the laminated structure was never actually penetrated...16 METEOROID & DEBRIS SPECIAL INVESTIGATION GROUP Impacts into laminated polymeric films, such as the Kapton test specimens on experiment A0138...several layers of carbon, glass, and/or Kevlar woven fiber cloth laminated together with resin binders. Impact features in these materials were

Space Shuttle Projects

NASA Image and Video Library

1990-01-08

Five astronauts launched aboard the Space Shuttle Columbia on January 9, 1990 at 7:35:00am (EST) for the STS-32 mission. The crew included David C. Brandenstein, commander; James D. Weatherbee, pilot; and mission specialists Marsha S. Ivins, G. David Low, and Bonnie J. Dunbar. Primary objectives of the mission were the deployment of the SYNCOM IV-F5 defense communications satellite and the retrieval of NASA’s Long Duration Exposure Facility (LDEF).

Do sanitary ceramic workers have a worse presentation of chest radiographs or pulmonary function tests than other ceramic workers?

PubMed

Tsao, Yu-Chung; Liu, Su-Hsun; Tzeng, I-Shiang; Hsieh, Tsung-Han; Chen, Jau-Yuan; Luo, Jiin-Chyuan John

2017-03-01

Silicosis remains the most prevalent occupational disease worldwide. There have been no specific studies focusing on the association between exposure settings at work and the clinical severity in silicosis patients. In this study, we describe and compare the clinical characteristics and silicosis-associated exposure history at work among workers from several types of ceramic production facilities in Taiwan. We reviewed the medical records of 221 patients who were first diagnosed with silicosis at the Occupational Medicine Clinic of Northern Taiwan in 2012. For each patient, we collected data on demographic characteristics, smoking habits, working history, duration of exposure, and years on the first relevant job. We also retrieved clinical reports of the pulmonary function test and the baseline chest radiography used for silicosis staging. As compared to other ceramic workers, sanitary ceramic workers had a worse X-ray type (p=0.044), more advanced age (p<0.001), longer working duration (p=0.029), and a higher proportion of starting the first relevant job prior to the year 1975 (p=0.003). However, after adjusting for age, work duration, and an initial occupational exposure prior to 1975, sanitary ceramic workers showed a comparable risk for worse X-ray findings to other ceramic workers (adjusted odds ratio=1.18, p=0.704). Results of multivariable regression models on individual lung function parameter also suggested comparably impaired lung function tests between sanitary and other ceramic workers (p>0.05). In this study, we found that sanitary ceramic workers were at a similar risk to other ceramic workers for moderate to severe silicosis when older age and longer working duration were accounted for. Copyright © 2016. Published by Elsevier B.V.

Summary of ionizing radiation analysis on the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Parnell, T. A.

1992-01-01

The ionizing radiation measurements flown on the Long Duration Exposure Facility (LDEF) were contained in 15 experiments which utilized passive detectors to pursue objectives in astrophysics and to measure the radiation environment and dosimetric quantities. The spacecraft structure became sufficiently radioactive to permit additional important studies. The induced activity allows extensive radiation mapping in the structure, and independent comparison with experiment dosimetric techniques, and significant studies of secondary effects. The long exposure time, attitude stability, and number and types of measurements produced a unique and critical set of data for low Earth orbit that will not be duplicated for more than a decade. The data allow an unprecedented test, and improvement if required, of models of the radiation environment and the radiation transport methods that are used to calculate the internal radiation and its effects in spacecraft. Results of measurements in the experiments, as well as from radioactivity in the structure, have clearly shown effects from the directional properties of the radiation environment, and progress was made in the dosimetric mapping of LDEF. These measurements have already influenced some Space Station Freedom design requirements. Preliminary results from experiments, reported at this symposium and in earlier papers, show that the 5.8 years exposure considerably enhanced the scientific return of the radiation measurements. The early results give confidence that the experiments will make significant advances in the knowledge of ultra heavy cosmic rays, anomalous cosmic rays, and heavy ions trapped in the radiation belts. Unexpected phenomena were observed, which require explanation. These include stopping iron group ions between the energy ranges anticipated for anomalous and galactic cosmic rays in the LDEF orbit. A surprising concentration of the Be-7 nuclide was discovered on the 'front' surface of LDEF, apparently transported up from the stratosphere with exceptional efficiency.

Olfactory function in chemical workers exposed to acrylate and methacrylate vapors.

PubMed Central

Schwartz, B S; Doty, R L; Monroe, C; Frye, R; Barker, S

1989-01-01

An investigation of the olfactory function of 731 workers at a chemical facility which manufacturers acrylates and methacrylates was undertaken using a standardized quantitative test. In a cross-sectional analysis of the data, no associations of chemical exposure with olfactory test scores were observed. A nested case-control study designed to evaluate the cumulative effects of exposure on olfactory function, however, revealed elevated crude exposure odds ratios (95% confidence interval) of 2.0 (1.1, 3.8) for all workers and 6.0 (1.7, 21.5) for workers who never smoked cigarettes. Logistic regression analysis, adjusting for multiple confounders, revealed exposure odds ratios of 2.8 (1.1, 7.0) and 13.5 (2.1, 87.6) in these same groups, respectively, and a dose-response relationship between olfactory dysfunction and cumulative exposure scores--semi-quantitative indices of lifetime exposure to the acrylates. The data also revealed decreasing exposure odds ratios with increasing duration since last exposure to these chemicals, suggesting that the effects may be reversible. PMID:2784947

Study of activation of metal samples from LDEF-1 and Spacelab-2

NASA Technical Reports Server (NTRS)

Laird, C. E.

1991-01-01

The activation of metal samples and other material orbited onboard the Long Duration Exposure Facility (LDEF) and Spacelab-2 were studied. Measurements of the radioactivities of spacecraft materials were made, and corrections for self-absorption and efficiency were calculated. Activation cross sections for specific metal samples were updated while cross sections for other materials were tabulated from the scientific literature. Activation cross sections for 200 MeV neutrons were experimentally determined. Linear absorption coefficients, half lives, branching ratios and other pertinent technical data needed for LDEF sample analyses were tabulated. The status of the sample counting at low background facilities at national laboratories is reported.

Space environmental effects on silvered Teflon thermal control surfaces

NASA Technical Reports Server (NTRS)

Hemminger, C. S.; Stuckey, W. K.; Uht, J. C.

1991-01-01

Cumulative space environment effects on Ag/fluorinated ethylene propylene (FEP) were a function of exposure orientation. Samples from nineteen silvered Teflon (Ag/FEP) thermal control surfaces recovered from the Long Duration Exposure Facility (LDEF) were analyzed to determine changes in this material as a function of position on the spacecraft. Although solar absorptance and infrared emittance of measured thermal blanket specimens are relatively unchanged from control specimen values, significant changes in surface morphology, composition and chemistry were observed. Researchers hypothesize that the FEP surfaces on LDEF were degraded by ultraviolet radiation exposure at all orientations, but that the damaged material had been removed by erosion from the blankets exposed to atomic oxygen flux and that contamination is masking the damage on trays flanking the trailing edge.

Atomic research

NASA Technical Reports Server (NTRS)

Hadaway, James B.; Connatser, Robert; Cothren, Bobby; Johnson, R. B.

1993-01-01

Work performed by the University of Alabama in Huntsville's (UAH) Center for Applied Optics (CAO) entitled Atomic Research is documented. Atomic oxygen (AO) effects on materials have long been a critical concern in designing spacecraft to withstand exposure to the Low Earth Orbit (LEO) environment. The objective of this research effort was to provide technical expertise in the design of instrumentation and experimental techniques for analyzing materials exposed to atomic oxygen in accelerated testing at NASA/MSFC. Such testing was required to answer fundamental questions concerning Space Station Freedom (SSF) candidate materials and materials exposed to atomic oxygen aboard the Long-Duration Exposure Facility (LDEF). The primary UAH task was to provide technical design, review, and analysis to MSFC in the development of a state-of-the-art 5eV atomic oxygen beam facility required to simulate the RAM-induced low earth orbit (LEO) AO environment. This development was to be accomplished primarily at NASA/MSFC. In support of this task, contamination effects and ultraviolet (UV) simulation testing was also to be carried out using NASA/MSFC facilities. Any materials analysis of LDEF samples was to be accomplished at UAH.

Health effects of gasoline exposure. I. Exposure assessment for U.S. distribution workers.

PubMed Central

Smith, T J; Hammond, S K; Wong, O

1993-01-01

Personal exposures were estimated for a large cohort of workers in the U.S. domestic system for distributing gasoline by trucks and marine vessels. This assessment included development of a rationale and methodology for extrapolating vapor exposures prior to the availability of measurement data, analysis of existing measurement data to estimate task and job exposures during 1975-1985, and extrapolation of truck and marine job exposures before 1975. A worker's vapor exposure was extrapolated from three sets of factors: the tasks in his or her job associated with vapor sources, the characteristics of vapor sources (equipment and other facilities) at the work site, and the composition of petroleum products producing vapors. Historical data were collected on the tasks in job definitions, on work-site facilities, and on product composition. These data were used in a model to estimate the overall time-weighted-average vapor exposure for jobs based on estimates of task exposures and their duration. Task exposures were highest during tank filling in trucks and marine vessels. Measured average annual, full-shift exposures during 1975-1985 ranged from 9 to 14 ppm of total hydrocarbon vapor for truck drivers and 2 to 35 ppm for marine workers on inland waterways. Extrapolated past average exposures in truck operations were highest for truck drivers before 1965 (range 140-220 ppm). Other jobs in truck operations resulted in much lower exposures. Because there were few changes in marine operations before 1979, exposures were assumed to be the same as those measured during 1975-1985. Well-defined exposure gradients were found across jobs within time periods, which were suitable for epidemiologic analyses. PMID:8020436

Summary of solar cell data from the Long Duration Exposure Facility (LDEF)

NASA Technical Reports Server (NTRS)

Hill, David C.; Rose, M. Frank

1994-01-01

The contractor has obtained and reviewed data relating solar cells assemblies (SCA's) flown as part of the following LDEF experiments: the Advanced Photovoltaic Experiment (S0014); the Solar Array Materials Passive LDEF Experiment (A0171); the Advanced Solar Cell and Coverglass Analysis Experiment (M0003-4); the LDEF Heat Pipe Experiment (S1001); the Evaluation of Thermal Control Coatings Y Solar Cells Experiment (S1002); and the Space Plasma-High Voltage Drainage Experiment (A0054). Where possible, electrical data have been tabulated and correlated with various environmental effects, including meteoroid and debris impacts, radiation exposure, atomic oxygen exposure, contamination, UV radiation exposure, and thermal cycling. The type, configuration, and location of all SCA's are documented here. By gathering all data and results together, a comparison of the survivability of the various types and configurations can be made.

Cosmogenic radionuclides on LDEF: An unexpected Be-10 result

NASA Technical Reports Server (NTRS)

Gregory, J. C.; Albrecht, A.; Herzog, G.; Klein, J.; Middleton, R.; Dezfouly-Arjomandy, B.; Harmon, B. A.

1993-01-01

Following the discovery of the atmospheric derived cosmogenic radionuclide Be-7 on the Long Duration Exposure Facility (LDEF), a search began for other known nuclides produced by similar mechanisms. None of the others have the narrow gamma-ray line emission of Be-7 decay which enabled its rapid detection and quantification. A search for Be-10 atoms on LDEF clamp plates using accelerator mass spectrometry is described. An unexpected result was obtained.

Derivation of particulate directional information from analysis of elliptical impact craters on LDEF

NASA Technical Reports Server (NTRS)

Newman, P. J.; Mackay, N.; Deshpande, S. P.; Green, S. F.; Mcdonnell, J. A. M.

1993-01-01

The Long Duration Exposure Facility provided a gravity gradient stabilized platform which allowed limited directional information to be derived from particle impact experiments. The morphology of impact craters on semi-infinite materials contains information which may be used to determine the direction of impact much more accurately. We demonstrate the applicability of this technique and present preliminary results of measurements from LDEF and modelling of interplanetary dust and space debris.

Partial analysis of LDEF experiment A-0114

NASA Technical Reports Server (NTRS)

Gregory, John C.

1991-01-01

During the contract period, work concentrated on four main components. Data from the UAH silver pin hole camera was analyzed for determination of the mean Long Duration Exposure Facility (LDEF) satellite attitude and stability in orbit, to include pitch and yaw. Chemical testing performed on the AO-114 hot plate determined the form and locus of absorption of cosmogenic beryllium-7. Reaction rates of atomic oxygen with Kapton and other polymeric solids integrated over the whole LDEF orbital lifetime were analyzed. These rates were compared with the JSC estimated values for Space Station exposures. Metal and polymer films exposed on A0114 (C-9 and C-3 plates) were also analyzed.

Surface analysis of anodized aluminum clamps from NASA-LDEF satellite

NASA Technical Reports Server (NTRS)

Grammer, H. L.; Wightman, J. P.; Young, Philip R.

1992-01-01

Surface analysis results of selected anodized aluminum clamps containing black (Z306) and white (A276) paints which received nearly six years of Low Earth Orbit (LEO) exposure on the Long Duration Exposure Facility are reported. Surface analytical techniques, including x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and scanning electron microscopy/energy dispersive analysis by x-ray (SEM/EDAX), showed significant differences in the surface composition of these materials depending upon the position on the LDEF. Differences in the surface composition are attributed to varying amounts of atomic oxygen and vacuum ultraviolet radiation (VUV). Silicon containing compounds were the primary contaminant detected on the materials.

Radiation model predictions and validation using LDEF satellite data

NASA Technical Reports Server (NTRS)

Armstrong, T. W.; Colborn, B. L.

1993-01-01

Predictions and comparisons with the radiation dose measurements on Long Duration Exposure Facility (LDEF) by thermoluminescent dosimeters were made to evaluate the accuracy of models currently used in defining the ionizing radiation environment for low Earth orbit missions. The calculations include a detailed simulation of the radiation exposure (altitude and solar cycle variations, directional dependence) and shielding effects (three-dimensional LDEF geometry model) so that differences in the predicted and observed doses can be attributed to environment model uncertainties. The LDEF dose data are utilized to assess the accuracy of models describing the trapped proton flux, the trapped proton directionality, and the trapped electron flux.

Scanning Tunneling Microscopy analysis of space-exposed polymer films

NASA Technical Reports Server (NTRS)

Kalil, Carol R.; Young, Philip R.

1993-01-01

The characterization of the surface of selected space-exposed polymer films by Scanning Tunneling Microscopy (STM) is reported. Principles of STM, an emerging new technique for materials analysis, are reviewed. The analysis of several films which received up to 5.8 years of low Earth orbital (LEO) exposure onboard the NASA Long Duration Exposure Facility (LDEF) is discussed. Specimens included FEP Teflon thermal blanket material, Kapton film, and several experimental polymer films. Ultraviolet and atomic oxygen-induced crazing and erosion are described. The intent of this paper is to demonstrate how STM is enhancing the understanding of LEO space environmental effects on polymer films.

Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1992

NASA Technical Reports Server (NTRS)

Horneck, G. (Editor); Buecher, H. (Editor); Cox, A. (Editor); Todd, P. (Editor); Yang, T. C. (Editor); Worgul, B. V. (Editor); Donlon, M. (Editor); Atwell, W. (Editor); Shea, M. A. (Editor); Smart, D. F. (Editor)

1994-01-01

Papers presented on long-term exposure to ionizing radiation, obtained from the Long Duration Exposure Facility, included radiation monitoring, radiation effects, and dosimetry. Mechanisms of biological systems, especially cells, under ionizing radiation and relative biological effectiveness were compared. The role of HZE particles as agents of mutation were reported from plant, animal, and in vitro models. Data on known and predicted effects of cosmic rays and other solar radiation on biological systems included differences related to Linear Energy Transfer and heavy ion particles.

Thermal control surfaces experiment: Initial flight data analysis

NASA Technical Reports Server (NTRS)

Wilkes, Donald R.; Hummer, Leigh L.

1991-01-01

The behavior of materials in the space environment continues to be a limiting technology for spacecraft and experiments. The thermal control surfaces experiment (TCSE) aboard the Long Duration Exposure Facility (LDEF) is the most comprehensive experiment flown to study the effects of the space environment on thermal control surfaces. Selected thermal control surfaces were exposed to the LDEF orbital environment and the effects of this exposure were measured. The TCSE combined in-space orbital measurements with pre and post-flight analyses of flight materials to determine the effects of long term space exposure. The TCSE experiment objective, method, and measurements are described along with the results of the initial materials analysis. The TCSE flight system and its excellent performance on the LDEF mission is described. A few operational anomalies were encountered and are discussed.

Flight projects overview

NASA Technical Reports Server (NTRS)

Levine, Jack

1988-01-01

Information is given in viewgraph form on the activities of the Flight Projects Division of NASA's Office of Aeronautics and Space Technology. Information is given on space research and technology strategy, current space flight experiments, the Long Duration Exposure Facility, the Orbiter Experiment Program, the Lidar In-Space Technology Experiment, the Ion Auxiliary Propulsion System, the Arcjet Flight Experiment, the Telerobotic Intelligent Interface Flight Experiment, the Cryogenic Fluid Management Flight Experiment, the Industry/University In-Space Flight Experiments, and the Aeroassist Flight Experiment.

Activation calculations for trapped protons below 200 MeV: Appendix

NASA Technical Reports Server (NTRS)

Laird, C. E.

1991-01-01

Tables are given displaying of the results of the activation calculations of metal samples and other material aboard the Long Duration Exposure Facility-1 (LDEF-1) and Spacelab-2 with the computer program, PTRAP4. The computer printouts give the reaction, the reactant product, the proton reaction cross sections as a function of the energy of the incident protons, and the activation as a function of distance into the sample from the exposed surface.

Long Duration Exposure Facility Space Optics Handbook

DTIC Science & Technology

1993-09-01

apparent (Ref. 12). The solar cell covers showed similar impact damage as the refractive optics components. 4-1020 Si i -i 10 • 4.12, Related Material...coatings, which worsens the synergistic A(0 0 cr()Sil Oi on Uateia IS, 11nd canl Upset olties, issoc iated telescope baffles, solar cells , star 0 0 trackers...and material processes which address S primarily solar array materials, including solar cell -, 0 composites, thin films, paints, metals and other

LDEF: 69 Months in Space. Third Post-Retrieval Symposium, part 3

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1995-01-01

This volume is a compilation of papers presented at the Third Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science. In addition, papers on preliminary data analysis of EURECA, EOIM-3, and other spacecraft are included.

Long Duration Exposure Facility experiment M0003 deintegration observation data base

NASA Technical Reports Server (NTRS)

Gyetvay, S. R.; Coggi, J. M.; Meshishnek, M. J.

1993-01-01

The four trays (2 leading edge and 2 trailing edge) of the M0003 materials experiment on the Long Duration Exposure Facility (LDEF) contained 1274 samples from 20 subexperiments. The complete sample complement represented a broad range of materials, including thin film optical coatings, paints, polymer sheets and tapes, adhesives, and composites, for use in various spacecraft applications, including thermal control, structures, optics, and solar power. Most subexperiments contained sets of samples exposed on both the leading and trailing edge trays of LDEF. Each individual sample was examined by high resolution optical microscope during the deintegration of the subexperiments from the M0003 trays. Observations of the post-flight condition of the samples made during this examination were recorded in a computer data base. The deintegration observation data base is available to requesters on floppy disk in 4th Dimension for the Macintosh format. Over 3,000 color macrographs and photomicrographs were shot to complement the observation records and to document the condition of the individual samples and of the M0003 trays. The photographs provide a visual comparison of the response of materials in leading and trailing edge LDEF environments. The Aerospace Corporate Archives is distributing photographs of the samples and hard copies of the database records to the general public upon request. Information on obtaining copies of the data base disks and for ordering photographs and records of specific samples or materials are given.

Space environmental effects on spacecraft: LEO materials selection guide, part 1

NASA Astrophysics Data System (ADS)

Silverman, Edward M.

1995-08-01

This document provides performance properties on major spacecraft materials and subsystems that have been exposed to the low-Earth orbit (LEO) space environment. Spacecraft materials include metals, polymers, composites, white and black paints, thermal-control blankets, adhesives, and lubricants. Spacecraft subsystems include optical components, solar cells, and electronics. Information has been compiled from LEO short-term spaceflight experiments (e.g., space shuttle) and from retrieved satellites of longer mission durations (e.g., Long Duration Exposure Facility). Major space environment effects include atomic oxygen (AO), ultraviolet radiation, micrometeoroids and debris, contamination, and particle radiation. The main objective of this document is to provide a decision tool to designers for designing spacecraft and structures. This document identifies the space environments that will affect the performance of materials and components, e.g., thermal-optical property changes of paints due to UV exposures, AO-induced surface erosion of composites, dimensional changes due to thermal cycling, vacuum-induced moisture outgassing, and surface optical changes due to AO/UV exposures. Where appropriate, relationships between the space environment and the attendant material/system effects are identified. Part 1 covers spacecraft design considerations for the space environment; advanced composites; polymers; adhesives; metals; ceramics; protective coatings; and lubricants, greases, and seals.

Space environmental effects on spacecraft: LEO materials selection guide, part 2

NASA Astrophysics Data System (ADS)

Silverman, Edward M.

1995-08-01

This document provides performance properties on major spacecraft materials and subsystems that have been exposed to the low-Earth orbit (LEO) space environment. Spacecraft materials include metals, polymers, composites, white and black paints, thermal-control blankets, adhesives, and lubricants. Spacecraft subsystems include optical components, solar cells, and electronics. Information has been compiled from LEO short-term spaceflight experiments (e.g., space shuttle) and from retrieved satellites of longer mission durations (e.g., Long Duration Exposure Facility). Major space environment effects include atomic oxygen (AO), ultraviolet radiation, micrometeoroids and debris, contamination, and particle radiation. The main objective of this document is to provide a decision tool to designers for designing spacecraft and structures. This document identifies the space environments that will affect the performance of materials and components, e.g., thermal-optical property changes of paints due to UV exposures, AO-induced surface erosion of composites, dimensional changes due to thermal cycling, vacuum-induced moisture outgassing, and surface optical changes due to AO/UV exposures. Where appropriate, relationships between the space environment and the attendant material/system effects are identified. Part 2 covers thermal control systems, power systems, optical components, electronic systems, and applications.

Space environmental effects on spacecraft: LEO materials selection guide, part 2

NASA Technical Reports Server (NTRS)

Silverman, Edward M.

1995-01-01

This document provides performance properties on major spacecraft materials and subsystems that have been exposed to the low-Earth orbit (LEO) space environment. Spacecraft materials include metals, polymers, composites, white and black paints, thermal-control blankets, adhesives, and lubricants. Spacecraft subsystems include optical components, solar cells, and electronics. Information has been compiled from LEO short-term spaceflight experiments (e.g., space shuttle) and from retrieved satellites of longer mission durations (e.g., Long Duration Exposure Facility). Major space environment effects include atomic oxygen (AO), ultraviolet radiation, micrometeoroids and debris, contamination, and particle radiation. The main objective of this document is to provide a decision tool to designers for designing spacecraft and structures. This document identifies the space environments that will affect the performance of materials and components, e.g., thermal-optical property changes of paints due to UV exposures, AO-induced surface erosion of composites, dimensional changes due to thermal cycling, vacuum-induced moisture outgassing, and surface optical changes due to AO/UV exposures. Where appropriate, relationships between the space environment and the attendant material/system effects are identified. Part 2 covers thermal control systems, power systems, optical components, electronic systems, and applications.

Space environmental effects on spacecraft: LEO materials selection guide, part 1

NASA Technical Reports Server (NTRS)

Silverman, Edward M.

1995-01-01

This document provides performance properties on major spacecraft materials and subsystems that have been exposed to the low-Earth orbit (LEO) space environment. Spacecraft materials include metals, polymers, composites, white and black paints, thermal-control blankets, adhesives, and lubricants. Spacecraft subsystems include optical components, solar cells, and electronics. Information has been compiled from LEO short-term spaceflight experiments (e.g., space shuttle) and from retrieved satellites of longer mission durations (e.g., Long Duration Exposure Facility). Major space environment effects include atomic oxygen (AO), ultraviolet radiation, micrometeoroids and debris, contamination, and particle radiation. The main objective of this document is to provide a decision tool to designers for designing spacecraft and structures. This document identifies the space environments that will affect the performance of materials and components, e.g., thermal-optical property changes of paints due to UV exposures, AO-induced surface erosion of composites, dimensional changes due to thermal cycling, vacuum-induced moisture outgassing, and surface optical changes due to AO/UV exposures. Where appropriate, relationships between the space environment and the attendant material/system effects are identified. Part 1 covers spacecraft design considerations for the space environment; advanced composites; polymers; adhesives; metals; ceramics; protective coatings; and lubricants, greases, and seals.

Evaluation of seals, lubricants, and adhesives used on LDEF

NASA Technical Reports Server (NTRS)

Dursch, Harry; Keough, Bruce; Pippin, Gary

1993-01-01

A wide variety of seals, lubricants, and adhesives were used on the Long Duration Exposure Facility (LDEF). The results, to date, of the Systems Special Investigation Group (SIG) and the Materials SIG investigation into the effect of the long term low Earth orbit (LEO) exposure on these materials is discussed. Results of this investigation show that if the material was shielded from exposure to LDEF's external environment, the 69 month exposure to LEO had minimal effect on the material. However, if the material was on LDEF's exterior surface, a variety of events occurred ranging from no material change, to changes in mechanical or physical properties, to complete disappearance of the material. The results are from the following sources: (1) visual examinations and/or testing of materials performed by various LDEF experimenters, (2) testing done at Boeing in support of the Materials or Systems SIG investigations, (3) testing done at Boeing on Boeing hardware flown on LDEF.

Evaluation of adhesive materials used on the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Dursch, H. W.; Keough, B. K.; Pippin, H. G.

1995-01-01

The adhesive and adhesive-like materials flown on LDEF included epoxies and silicones (including lap shear specimens), conformal coatings, potting compounds, and several tapes and transfer films. With the exception of the lap shear specimens, these materials were used in the fabrication and assembly of the experiments such as bonding thermal control surfaces to other hardware and holding individual specimens in place, similar to applications on other spacecraft. Typically, the adhesives were not exposed to solar radiation or atomic oxygen. Only one adhesive system was used in a structural application. This report documents all results of the Materials and Systems SIG investigation into the effect of long term low Earth orbit (LEO) exposure of these materials. Results of this investigation show that if the material was shielded from exposure to LDEF's external environment, the 69 month exposure to LEO had, in most cases, minimal effect on the material.

Effects of long-term exposure on LDEF fastener assemblies

NASA Astrophysics Data System (ADS)

Spear, Steve; Dursch, Harry

1992-09-01

This presentation summarizes the Systems Special Investigations Group (SIG) findings from testing and analysis of fastener assemblies used on the Long Duration Exposure Facility (LDEF) structure, the tray mounting clamps, and by the various experimenters. The LDEF deintegration team and several experimenters noted severe fastener damage and hardware removal difficulties during post-flight activities. The System SIG has investigated all reported instances, and in all cases examined to date, the difficulties were attributed to galling during installation or post-flight removal. To date, no evidence of coldwelding was found. Correct selection of materials and lubricants as well as proper mechanical procedures is essential to ensure successful on-orbit or post-flight installation and removal of hardware.

Effects of long-term exposure on LDEF fastener assemblies

NASA Technical Reports Server (NTRS)

Spear, Steve; Dursch, Harry

1992-01-01

This presentation summarizes the Systems Special Investigations Group (SIG) findings from testing and analysis of fastener assemblies used on the Long Duration Exposure Facility (LDEF) structure, the tray mounting clamps, and by the various experimenters. The LDEF deintegration team and several experimenters noted severe fastener damage and hardware removal difficulties during post-flight activities. The System SIG has investigated all reported instances, and in all cases examined to date, the difficulties were attributed to galling during installation or post-flight removal. To date, no evidence of coldwelding was found. Correct selection of materials and lubricants as well as proper mechanical procedures is essential to ensure successful on-orbit or post-flight installation and removal of hardware.

Continued results of the seeds in space experiment

NASA Technical Reports Server (NTRS)

Alston, Jim A.

1993-01-01

Two million seeds of 120 different varieties representing 106 species, 97 genera, and 55 plant families were flown aboard the Long Duration Exposure Facility (LDEF). The seed were housed on the Space Exposed Experiment Developed for Students (SEEDS) tray in the sealed canister number 6 and in two small vented canisters. The tray was in the F-2 position. The seed were germinated and the germination rates and the development of the resulting plants were compared to the performance of the control seed that stayed in Park Seed's seed storage facility. The initial results were presented in a paper at the First LDEF Post-Retrieval Symposium. There was a better survival rate of the seed in the sealed canister in space than in the storage facility at Park Seed. At least some of the seed in each of the vented canisters survived the exposure to vacuum for almost six years. The number of observed apparent mutations was very low. In the initial testing, the small seeded crops were not grown to maturity to check for mutations and obtain second generation seed. These small seeded crops have now been grown for evaluation and second generation seed collected.

A case-control study of chronic neuropsychiatric disease and organic solvent exposure in automobile assembly plant workers.

PubMed Central

Nelson, N A; Robins, T G; White, R F; Garrison, R P

1994-01-01

A case-control study of chronic neurological and psychiatric disease and occupational exposure to solvents was carried out in eight automobile assembly plants. Cases included 299 subjects who were granted medical disability retirement in 1980-8. Two control groups were selected, the first from those granted retirement in the same period because of medical disability from causes unrelated to solvent exposure. The second included hourly employees from the plant population. In these facilities, solvent exposures tended to be short term and low level, although common: the average duration of exposure was 2.3 years; about 41% experienced at least one day of exposure. Of those exposed, 46% had less than one year of exposure. Results for all psychiatric disease combined (273 cases) suggested that cases had lower exposures than either control group, regardless of how exposure was expressed. Results could not be explained by conventional confounding exposures or characteristics or by usual manifestations of the healthy worker effect. By contrast, chronic neurological disease, and multiple sclerosis in particular, seemed to be associated with exposure, although few cases were identified and observed increases in risk were not statistically significant. PMID:8199679

Retrospective Assessment of Exposure to Chemicals for a Microelectronics and Business Machine Manufacturing Facility

PubMed Central

Fleming, Donald A.; Woskie, Susan R.; Jones, James H.; Silver, Sharon R.; Luo, Lian; Bertke, Stephen J.

2015-01-01

A retrospective exposure assessment was performed for use in a health outcomes study of a facility manufacturing circuit boards, business machines, and other equipment during the years 1969–2002. A matrix was developed identifying chemical use by department-year based on company-provided information. Use of six chemical agents (fiberglass, lead, methylene chloride, methyl chloroform, perchloroethylene, and trichloroethylene) and six chemical classes (acid-base, aromatic hydrocarbons, chlorinated hydrocarbons, other hydrocarbons, chlorofluorocarbons, and metals), and general (including unspecified) chemicals was identified. The matrix also contained an assignment for each department-year categorizing the potential for use of chemicals as negligible, intermittent/incidental, or routine. These department-based exposure matrix data were combined with work history data to provide duration of potential chemical use for workers. Negligible, intermittent/incidental or routine extent-of-chemical-use categories comprised 42.6%, 39.4%, and 17.9%, respectively, of total person-years of employment. Cumulative exposure scores were also developed, representing a relative measure of the cumulative extent of potential exposure to the six chemical agents, six chemical classes, and general (including unspecified) chemicals. Additionally, the study period was divided into manufacturing eras showing trends in chemical use, and showing that process use of trichloroethylene and methylene chloride ended in the mid-1980s and the mid-1990s, respectively. This approach may be useful in other assessments addressing a variety of chemicals, and with data constraints common to retrospective chemical exposure studies. PMID:24224613

LDEF: 69 Months in Space. Third Post-Retrieval Symposium, part 1

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1995-01-01

This volume (Part 1 of 3) is a compilation of papers presented at the Third Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science. In addition, papers on preliminary data analysis of EURECA, EOIM-3, and other spacecraft are included.

LDEF Materials/Contamination

NASA Technical Reports Server (NTRS)

Pippin, Gary

1997-01-01

This pictorial presentation reviews the post-flight analysis results from two type of hardware (tray clamp bolt heads and uhcre flight experiment tray walls) from the Long Duration Exposure Facility (LDEF). It will also discuss flight hardware for one upcoming (Effects of the Space Environment on Materials (ESEM) flight experiment), and two current flight experiments evaluating the performance of materials in space (Passive Optical Sample Assembly (POSA) 1&2 flight experiments. These flight experiments also are concerned with contamination effects which will also be discussed.

LDEF Experiment P0006 Linear Energy Transfer Spectrum Measurement (LETSME) quick look report

NASA Technical Reports Server (NTRS)

1990-01-01

A preliminary analysis of the various passive radiation detector materials included in the P0006 LETSME experiment flown on LDEF (Long Duration Exposure Facility) is presented. It consists of four tasks: (1) readout and analysis of thermoluminescent detectors (TLD); (2) readout and analysis of fission foil/mica detectors; (3) readout and analysis of (6)LiF/CR-39 detectors; and (4) preliminary processing and readout of CR-39 and polycarbonate plastic nuclear track detectors (PNTD).

Durability of reflector materials in the space environment

NASA Technical Reports Server (NTRS)

Whitaker, Ann F.; Finckenor, Miria M.; Edwards, David; Kamenetzky, Rachel R.; Linton, Roger C.

1995-01-01

Various reflector configurations were flown as part of the Long Duration Exposure Facility (LDEF) A0171 experiment. These reflectors consisted of nickel substrates with aluminum, enhanced aluminum (multiple layers of aluminum and silver), silver, and silver alloy coatings with glassy ceramic overcoatings. These samples have been evaluated for changes in reflectance due to 5.8 years in the space environment. The reflector materials have also been evaluated using angstrometer, Rutherford backscattering (RBS), and electron spectroscopy for chemical analysis (ESCA) techniques.

Thermal-vacuum response of polymer matrix composites in space

NASA Technical Reports Server (NTRS)

Tennyson, R. C.; Matthews, R.

1993-01-01

This report describes a thermal-vacuum outgassing model and test protocol for predicting outgassing times and dimensional changes for polymer matrix composites. Experimental results derived from 'control' samples are used to provide the basis for analytical predictions to compare with the outgassing response of Long Duration Exposure Facility (LDEF) flight samples. Coefficient of thermal expansion (CTE) data are also presented. In addition, an example is given illustrating the dimensional change of a 'zero' CTE laminate due to moisture outgassing.

System related testing and analysis of FRECOPA

NASA Technical Reports Server (NTRS)

Durin, Christian

1992-01-01

Results from the French Cooperative Payload (FRECOPA) system analysis are presented. It was one of the numerous experiments which were flown on the Long Duration Exposure Facility (LDEF) satellite. In our flight configuration (LEO orbit, trailing edge), the environment was a better vacuum than the leading edge, with many thermal cycles (32000) and a large amount of UV radiation (11100 equivalent sun hours). Also, the satellite was mainly bombarded by micro-particles. It saw a low atomic flux and minor doses of protons and electrons.

In orbit degradation of EUV optical components in the wavelength range 10-40 nm AO 138-3

NASA Technical Reports Server (NTRS)

Delaboudiniere, J. P.; Carabetian, C.; Hochedez, J. F.

1993-01-01

A complement of EUV optical components, including mirrors and thin film filters, was flown as part of the Long Duration Exposure Facility (LDEF) AO 138-3. The most original amongst these components were multilayered interference reflectors for the 10-40 nm wavelength range. Very moderate degradation was observed for those components which were exposed to the sun. The degradation is compatible with the deposition of a few nanometers of absorbing material on the surface of the samples.

LDEF: 69 Months in Space. Third Post-Retrieval Symposium, part 2

NASA Technical Reports Server (NTRS)

Levine, Arlene S. (Editor)

1995-01-01

This volume is a compilation of papers presented at the Third Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science. In addition, papers on preliminary data analysis of EURECA, EOIM-3, and other spacecraft are included. This second of three parts covers spacecraft construction materials.

Long duration exposure facility solar illumination data package

NASA Technical Reports Server (NTRS)

Berrios, William M.; Sampair, Thomas

1990-01-01

A post flight solar illumination data package was created by the LDEF thermal analysis data group in support of the LDEF science office data group. The data presented was prepared with the Thermal Radiation Analysis System (TRASYS) program. Ground tracking data was used to calculate daily orbital beta angles for the calculation of resultant fluxes. This data package will be useful in calculation of solar illumination fluent for a variety of beta angle orbital conditions encountered during the LDEF mission.

Space Flight Applications of Optical Fiber; 30 Years of Space Flight Success

NASA Technical Reports Server (NTRS)

Ott, Melanie N.

2010-01-01

For over thirty years NASA has had success with space flight missions that utilize optical fiber component technology. One of the early environmental characterization experiments that included optical fiber was launched as the Long Duration Exposure Facility in 1978. Since then, multiple missions have launched with optical fiber components that functioned as expected, without failure throughout the mission life. The use of optical fiber in NASA space flight communications links and exploration and science instrumentation is reviewed.

Systems special investigation group

NASA Technical Reports Server (NTRS)

1991-01-01

An interim report concerning the Long Duration Exposure Facility (LDEF) is presented by a Boeing Systems special investigation group (SIG). The SIG activities were divided into five engineering disciplines: electrical, mechanical, optics, thermal, and batteries/solar cells. The responsibilities of the SIG included the following areas: support de-integration at Kennedy Space Center (KSC); testing of hardware at Boeing; review of principal investigator (PI) test plans and test results; support of test activities at PI labs; and collation of all test results into the SIG database.

LDEF grappled by remote manipulator system (RMS) during STS-32 retrieval

NASA Image and Video Library

1990-01-20

This view taken through overhead window W7 on Columbia's, Orbiter Vehicle (OV) 102's, aft flight deck shows the Long Duration Exposure Facility (LDEF) in the grasp of the remote manipulator system (RMS) during STS-32 retrieval activities. Other cameras at eye level were documenting the bus-sized spacecraft at various angles as the RMS manipulated LDEF for a lengthy photo survey. The glaring celestial body in the upper left is the sun with the Earth's surface visible below.

Effects of atomic oxygen on polymeric materials flown on EOIM-3

NASA Technical Reports Server (NTRS)

Kamenetzky, Rachel R.; Linton, Roger C.; Finckenor, Miria M.; Vaughn, Jason A.

1995-01-01

Diverse polymeric materials, including several variations of Kapton, were flown on STS-46 as part of the Evaluation of Oxygen Interaction with Materials Experiment (EOIM-3). These materials were flown in the cargo bay and exposed to the space environment July 31 - August 8, 1992, including 40 hours of direct atomic oxygen impingement. The atomic oxygen exposure was approximately 2.2 x 10(exp 20) atoms/sq cm. Polymeric materials flown on EOIM-3 include coated and uncoated Kapton, Tefzel ETFE, Lexan, FEP and TFE Teflon, bulk Halar and PEEK, S383 silicone and Viton elastomeric seal material. Analyses performed included thickness measurements using Dektak and eddy current methods, mass loss, resistance, permeability, hardness, and FTIR. The effects of stress and the space environment on Kapton were also evaluated. Previous EOIM missions on STS-5 and STS-8 and the Long Duration Exposure Facility also contained polymeric material samples. Data from these previous flights are shown for comparison, as well as ground simulation of space environment effects using both thermal energy flow tubes and 5 eV neutral atomic oxygen beam facilities. Reaction efficiencies for the various atomic oxygen exposure conditions are discussed.

Polymer matrix composites on LDEF experiments M0003-9 and M0003-10

NASA Technical Reports Server (NTRS)

Steckel, Gary L.; Cookson, Thomas; Blair, Christopher

1992-01-01

Over 250 polymer matrix composites were exposed to the natural space environment on Long Duration Exposure Facility (LDEF) experiments M0003-9 and 10. The experiments included a wide variety of epoxy, thermoplastic, polyimide, and bismalimide matrix composites reinforced with graphite, glass, or organic fibers. A review of the significant observations and test results obtained to date is presented. Estimated recession depths from atomic oxygen exposure are reported and the resulting surface morphologies are discussed. The effects of the LDEF exposure on the flexural strength and modulus, short beam shear strength, and coefficient of thermal expansion of several classes of bare and coated composites are reviewed. Lap shear data are presented for composite-to-composite and composite-to-aluminum alloy samples that were prepared using different bonding techniques and subsequently flown on LDEF.

Residential Proximity to Industrial Facilities and Risk of Non-Hodgkin Lymphoma

PubMed Central

De Roos, AJ; Davis, S; Colt, JS; Blair, A; Airola, M; Severson, RK; Cozen, W; Cerhan, JR; Hartge, P; Nuckols, JR; Ward, MH

2009-01-01

Industrial pollution has been suspected as a cause of non-Hodgkin lymphoma (NHL), based on associations with chemical exposures in occupational studies. We conducted a case-control study of NHL in four SEER regions of the United States, in which residential locations of 864 cases and 684 controls during the 10 years before recruitment were used to characterize proximity to industrial facilities reporting chemical releases to the Environmental Protection Agency's Toxics Release Inventory (TRI). For each of 15 types of industry (by 2-digit SIC code), we evaluated the risk of NHL associated with having lived within 2 miles of a facility, the distance to the nearest facility (categories of ≤0.5-mile, >0.5-1.0, >1.0-2.0, >2 [referent]), and the duration of residence within 2 miles (10 years, 1-9, 0 [referent]), using logistic regression. Increased risk of NHL was observed in relation to lumber and wood products facilities (SIC 24) for the shortest distance of residential proximity (≤0.5-mile: odds ratio [OR]=2.2, 95% confidence interval [CI]: 0.4-11.8) or longest duration (10 years: OR=1.9, 95% CI: 0.8-4.8); the association with lumber facilities was more apparent for diffuse large B-cell lymphoma (lived within 2 miles: OR=1.7, 95% CI: 1.0-3.0) than for follicular lymphoma (OR=1.1, 95% CI: 0.5-2.2). We also observed elevated ORs for the chemical (SIC 28, 10 years: OR=1.5, 95% CI: 1.1-2.0), petroleum (SIC 29, 10 years: OR=1.9, 95% CI: 1.0-3.6), rubber/miscellaneous plastics products (SIC 30, ≤0.5-mile: OR=2.7, 95% CI: 1.0-7.4), and primary metal (SIC 33, lived within 2 miles: OR=1.3, 95% CI: 1.0-1.6) industries; however, patterns of risk were inconsistent between distance and duration metrics. This study does not provide strong evidence that living near manufacturing industries increases NHL risk. However, future studies designed to include greater numbers of persons living near specific types of industries, along with fate-transport modeling of chemical releases would be informative. PMID:19840879

Meteoroid and Debris Impact Features Documented on the Long Duration Exposure Facility: A Preliminary Report

NASA Technical Reports Server (NTRS)

See, T. (Compiler); Allbrooks, M. (Compiler); Atkinson, D. (Compiler); Simon, C. (Compiler); Zolensky, M. (Compiler)

1990-01-01

The Long Duration Exposure Facility (LDEF) was host to several individual experiments designed to characterize aspects of the meteoroid and space-debris environment in low-Earth orbit. It was realized from the very start, however, that the most complete way to accomplish this goal was to exploit the meteoroid and debris record of the entire LDEF. The Meteoroid and Debris Special Investigation Group (M&D SIG) was organized to achieve this end. Two dominant goals of the M&D SIG are the documentation of the impact record of the entire LDEF, and the dissemination of this information to all interested workers. As a major step towards the accomplishment of these goals, we have prepared this publication describing the M&D SIG observations of impact features made during LDEF deintegration activities at KSC in the spring of 1990. It is hoped that this report will serve as a useful guide for spacecraft designers as well as for meteoroid and space-debris workers, and that it will spur further work on the LDEF impact-laden surfaces collected by the M&D SIG and now available for allocation to qualified investigators. An important aim is to present all data and descriptions of impact features in a form which, though terse, remains comprehensible to the wider community. There is a deliberate minimum of interpretations. Thus, this catalog is intended to serve as a guide to the impact features found on LDEF and is not intended to stand as a definitive interpretive work.

Preliminary analysis of WL experiment number 701: Space environment effects on operating fiber optic systems

NASA Technical Reports Server (NTRS)

Taylor, E. W.; Padden, R. J.; Berry, J. N.; Sanchez, A. D.; Chapman, S. P.

1991-01-01

A brief overview of the analysis performed on WL Experiment number 701 is presented, highlighting the successful operation of the first know active fiber optic links orbited in space. Four operating fiber optic links were exposed to the space environment for a period exceeding five years, situated aboard and external to the Long Duration Exposure Facility (LDEF). Despite the prolonged space exposure to radiation, wide temperature extremums, atomic oxygen interactions, and micrometeorite and debris impacts, the optical data links performed well within specification limits. Early Phillips Laboratory tests and analyses performed on the experiment and its recovered magnetic tape data strongly indicate that fiber optic application in space will have a high success rate.

Analysis, review, and documentation of the activation data from LDEF material

NASA Technical Reports Server (NTRS)

Laird, C. E.

1992-01-01

Samples removed from Long Duration Exposure Facility (LDEF-1) are being studied at various laboratories to determine the specific activity(pCi/kg) produced in orbit by exposure to protons and neutrons in near-Earth orbit. These activities are being corrected for efficiency, self-attenuation, and background. The activities and associated gamma-ray spectra are being collected, analyzed, documented and reviewed by faculty and graduate students at Eastern Kentucky University. The currently available activation results have been tabulated and reviewed in this report. Approximately 500 spectra have been accumulated for future archival and analysis. The effect of the changing satellite orbit on the activation is reported herein and was calculated using more recent estimates of the flux of Van Allen belt protons.

Preparation of Interconnected Biomimetic Poly(vinylidene fluoride-co-chlorotrifluoroethylene) Hydrophobic Membrane by Tuning the Two-Stage Phase Inversion Process.

PubMed

Zheng, Libing; Wang, Jun; Wu, Zhenjun; Li, Jie; Zhang, Yong; Yang, Min; Wei, Yuansong

2016-11-30

A facile strategy was applied for poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) hydrophobic membrane preparation by tuning the two-stage phase inversion process. The exposure stage was found to benefit the solid-liquid demixing process (gelation/crystallization) induced by the solvent evaporation and the subsequent phase inversion induced by immersion benefit the liquid-liquid demixing. It was confirmed that the electrospun nanostructure-like biomimetic surface and interconnected pore structure can be expected by controlling the exposure duration, and 300 s was considered as the inflection point of exposure duration for PVDF-CTFE membrane through which a tremendous variation would show. The micro/nanohierarchical structure in the membrane surface owing to the crystallization of PVDF-CTFE copolymer was responsible for the improvement of membrane roughness and hydrophobicity. Meanwhile, the interconnected pore structure in both the surface and the cross-section, which were formed because of the crystallization process, offers more mass transfer passages and enhances the permeate flux. The membrane then showed excellent MD performance with high permeate flux, high salt rejection, and relatively high stability during a 48 h continuous DCMD operation, according to the morphology, pore structure, and properties, which can be a substitute for hydrophobic membrane application.

Short-term exposure to hypoxia for work and leisure activities in health and disease: which level of hypoxia is safe?

PubMed

Burtscher, Martin; Mairer, Klemens; Wille, Maria; Gatterer, Hannes; Ruedl, Gerhard; Faulhaber, Martin; Sumann, Günther

2012-06-01

Exposures to natural and simulated altitudes entail reduced oxygen availability and thus hypoxia. Depending on the level of hypoxia, the duration of exposure, the individual susceptibility, and preexisting diseases, health problems of variable severity may arise. Although millions of people are regularly or occasionally performing mountain sport activities, are transported by airplanes, and are more and more frequently exposed to short-term hypoxia in athletic training facilities or at their workplace, e.g., with fire control systems, there is no clear consensus on the level of hypoxia which is generally well tolerated by human beings when acutely exposed for short durations (hours to several days). Available data from peer-reviewed literature report adaptive responses even to altitudes below 2,000 m or corresponding normobaric hypoxia (F(i)O(2) > 16.4%), but they also suggest that most of exposed subjects without severe preexisting diseases can tolerate altitudes up to 3,000 m (F(i)O(2) > 14.5%) well. However, physical activity and unusual environmental conditions may increase the risk to get sick. Large interindividual variations of responses to hypoxia have to be expected, especially in persons with preexisting diseases. Thus, the assessment of those responses by hypoxic challenge testing may be helpful whenever possible.

Exposure to space radiation of high-performance infrared multilayer filters

NASA Technical Reports Server (NTRS)

Seeley, J. S.; Hawkins, G. J.; Hunneman, R.

1991-01-01

The University of Reading experiment exposed IR interference filters and crystal substrates on identical earth facing and leading-edge sites of the Long Duration Exposure Facility (LDEF). Filters mostly comprised multilayer coatings of lead telluride (PbTe)/II-IV on germanium (Ge) and other substrates: crystals comprised CdTe, MgF2, sapphire, quartz, silicon, and some softer materials. Identical control samples were maintained in the laboratory throughout the experiment. The filters were novel in their design, construction and manufacture, and categorized high-performance because of their ability to resolve emission spectra of the important atmospheric gases for various purposes in remote sensing. No significant changes were found in the spectra of the hard-coated filters or in the harder crystals (the softer materials were degraded to an extent). By virtue of this well-documented and long exposure in LDEF, the qualification of the filter type is significantly improved for its future requirements.

Migration and generation of contaminants from launch through recovery: LDEF case history

NASA Technical Reports Server (NTRS)

Crutcher, E. R.; Nishimura, L. S.; Warner, K. J.; Wascher, W. W.

1992-01-01

It is possible to recreate the contamination history of the Long Duration Exposure Facility (LDEF) through an analysis of its contaminants and selective samples that were collected from surfaces with better documented exposure histories. This data was then used to compare estimates based on monitoring methods that were selected for the purpose of tracking LDEF's exposure to contaminants. The LDEF experienced much more contamination than would have been assumed based on the monitors. Work is still in progress but much of what was learned so far is already being used in the selection of materials and in the design of systems for space. Now experiments are being prepared for flight to resolve questions created by the discoveries on the LDEF. A summary of what was learned about LDEF contaminants over the first year since recovery and deintegration is presented. Over 35 specific conclusions in 5 contamination related categories are listed.

Vacuum ultraviolet radiation/atomic oxygen synergism in fluorinated ethylene propylene Teflon erosion

NASA Technical Reports Server (NTRS)

Stiegman, A. E.; Brinza, David E.; Laue, Eric G.; Anderson, Mark S.; Liang, Ranty H.

1992-01-01

A micrographic investigation is reported of samples of the fluorinated ethylene propylene (FEP) Teflon thermal-blanketing materials recovered from the Long-Duration Exposure Facility (LDEF) satellite. The samples are taken from the trailing edge and row 8 which correspond to exposures to vacuum UV (VUV) and VUV + atomic O, respectively. Data are taken from SEM and IR-spectra observations, and the LDEF leading-edge FEP shows a high degree of erosion, roughening, and sharp peaks angled in the direction of the flow of atomic O. The trailing edge sample influenced primarily by VUV shows a hard brittle layer and some cracked mosaic patterns. Comparisons to a reference sample suggest that the brittle layer is related to exposure to VUV and is removed by atomic-O impingement. Polymers that are stable to VUV radiation appear to be more stable in terms of atomic oxygen.

Performance of silvered Teflon thermal control blankets on spacecraft

NASA Astrophysics Data System (ADS)

Pippin, G.; Stuckey, W. K.; Hemminger, C. S.

1993-03-01

Silver-backed fluorinated ethylene propylene Teflon (Ag/FEP) thin film material was used for thermal control in many locations on the Long Duration Exposure Facility (LDEF). The Ag/FEP registered the effects of atomic oxygen, solar ultraviolet radiation, meteoroid and debris impacts, thermal cycling, and contamination. This report summarizes the post-flight condition of the Ag/FEP, compares the results with performance on other spacecraft, and presents lifetime estimates for use under a variety of environmental exposures. Measurements of optical property and mechanical property and surface chemistry changes with exposure conditions, and their significance for design considerations and expected performance lifetimes, are reported for material flown on LDEF. The LDEF based data provides detailed information performance of Ag/FEP under relatively long term exposure in low Earth orbit. Comparison of this data with results from short term shuttle flights, Solar Max, SCATHA, other satellites, and ground based measurements is made to present a comprehensive summary of the use of this material for spacecraft applications.

LDEF microenvironments, observed and predicted

NASA Astrophysics Data System (ADS)

Bourassa, R. J.; Pippin, H. G.; Gillis, J. R.

1993-04-01

A computer model for prediction of atomic oxygen exposure of spacecraft in low earth orbit, referred to as the primary atomic oxygen model, was originally described at the First Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The primary atomic oxygen model accounts for variations in orbit parameters, the condition of the atmosphere, and for the orientation of exposed surfaces relative to the direction of spacecraft motion. The use of the primary atomic oxygen model to define average atomic oxygen exposure conditions for a spacecraft is discussed and a second microenvironments computer model is described that accounts for shadowing and scattering of atomic oxygen by complex surface protrusions and indentations. Comparisons of observed and predicted erosion of fluorinated ethylene propylene (FEP) thermal control blankets using the models are presented. Experimental and theoretical results are in excellent agreement. Work is in progress to expand modeling capability to include ultraviolet radiation exposure and to obtain more detailed information on reflecting and scattering characteristics of material surfaces.

LDEF microenvironments, observed and predicted

NASA Technical Reports Server (NTRS)

Bourassa, R. J.; Pippin, H. G.; Gillis, J. R.

1993-01-01

A computer model for prediction of atomic oxygen exposure of spacecraft in low earth orbit, referred to as the primary atomic oxygen model, was originally described at the First Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The primary atomic oxygen model accounts for variations in orbit parameters, the condition of the atmosphere, and for the orientation of exposed surfaces relative to the direction of spacecraft motion. The use of the primary atomic oxygen model to define average atomic oxygen exposure conditions for a spacecraft is discussed and a second microenvironments computer model is described that accounts for shadowing and scattering of atomic oxygen by complex surface protrusions and indentations. Comparisons of observed and predicted erosion of fluorinated ethylene propylene (FEP) thermal control blankets using the models are presented. Experimental and theoretical results are in excellent agreement. Work is in progress to expand modeling capability to include ultraviolet radiation exposure and to obtain more detailed information on reflecting and scattering characteristics of material surfaces.

Fluorescence observations of LDEF exposed materials as an indicator of induced material reactions

NASA Technical Reports Server (NTRS)

Linton, Roger C.; Whitaker, Ann F.; Kamenetzky, Rachel R.

1993-01-01

Observations and measurements of induced changes in the fluorescent emission of materials exposed to the space environment on the Long Duration Exposure Facility (LDEF) have revealed systematic patterns of material-dependent behavior. These results have been supplemented by inspection of similar materials exposed on previous Space Shuttle Missions and in laboratory testing. The space environmental factors affecting the fluorescence of exposed materials have been found to include (but are not necessarily limited to) solar ultraviolet (UV) radiation, atomic oxygen (AO), thermal vacuum exposure, and synergistic combinations of these factors. Observed changes in material fluorescent behavior include stimulation, quenching, and spectral band shifts of emission. For example, the intrinsic yellow fluorescence of zinc oxide pigmented thermal control coatings undergoes quenching as a result of exposure, while coloration is stimulated in the fluorescent emission of several polyurethane coating materials. The changes in fluorescent behavior of these materials are shown to be a revealing indicator of induced material reactions as a result of space environmental exposure.

Evaluation of adhesive materials used on the Long Duration Exposure Facility. Report, October 1989-January 1995

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

Dursch, H.W.; Keough, B.K.; Pippin, H.G.

1995-03-01

The adhesive and adhesive-like materials flown on LDEF included epoxies and silicones (including lap shear specimens), conformal coatings, potting compounds, and several tapes and transfer films. With the exception of the lap shear specimens, these materials were used in the fabrication and assembly of the experiments such as bonding thermal control surfaces to other hardware and holding individual specimens in place, similar to applications on other spacecraft. Typically, the adhesives were not exposed to solar radiation or atomic oxygen. Only one adhesive system was used in a structural application. This report documents all results of the Materials and Systems SIGmore » investigation into the effect of long term low Earth orbit (LEO) exposure of these materials. Results of this investigation show that if the material was shielded from exposure to LDEF`s external environment, the 69 month exposure to LEO had, in most cases, minimal effect on the material.« less

Future directions for LDEF ionizing radiation modeling and assessments

NASA Technical Reports Server (NTRS)

Armstrong, T. W.; Colborn, B. L.

1993-01-01

A calculational program utilizing data from radiation dosimetry measurements aboard the Long Duration Exposure Facility (LDEF) satellite to reduce the uncertainties in current models defining the ionizing radiation environment is in progress. Most of the effort to date has been on using LDEF radiation dose measurements to evaluate models defining the geomagnetically trapped radiation, which has provided results applicable to radiation design assessments being performed for Space Station Freedom. Plans for future data comparisons, model evaluations, and assessments using additional LDEF data sets (LET spectra, induced radioactivity, and particle spectra) are discussed.

Large craters on the meteoroid and space debris impact experiment

NASA Technical Reports Server (NTRS)

Humes, Donald H.

1991-01-01

The distribution around the Long Duration Exposure Facility (LDEF) of 532 large craters in the Al plates from the Meteoroid and Space Debris Impact Experiment (S0001) is discussed along with 74 additional large craters in Al plates donated to the Meteoroid and Debris Special Investigation Group by other LDEF experimenters. The craters are 0.5 mm in diameter and larger. Crater shape is discussed. The number of craters and their distribution around the spacecraft are compared with values predicted with models of the meteoroid environment and the manmade orbital debris environment.

Ionizing radiation measurements on LDEF: A0015 Free flyer biostack experiment

NASA Technical Reports Server (NTRS)

Benton, E. V.; Frank, A. L.; Benton, E. R.; Csige, I.; Frigo, L. A.

1995-01-01

This report covers the analysis of passive radiation detectors flown as part of the A0015 Free Flyer Biostack on LDEF (Long Duration Exposure Facility). LET (linear energy transfer) spectra and track density measurements were made with CR-39 and Polycarbonate plastic nuclear track detectors. Measurements of total absorbed dose were carried out using Thermoluminescent Detectors. Thermal and resonance neutron dose equivalents were measured with LiF/CR-39 detectors. High energy neutron and proton dose equivalents were measured with fission foil/CR-39 detectors.

Characterization of a space orbited incoherent fiber optic bundle

NASA Technical Reports Server (NTRS)

Dewalt, Stephen A.; Taylor, Edward W.

1993-01-01

The results of a study performed to determine the effects of adverse space environments on a bundle of over 1800 optical fibers orbited for 69 months are reported. Experimental results are presented on an incoherent fiber optic bundle oriented in low Earth orbit aboard the Long Duration Exposure Facility (LDEF) satellite as part of the Space Environment Effects Experiment (M0006). Measurements were performed to determine if space induced radiation effects changed the fiber bundle characteristics. Data demonstrating the success of light transmitting fibers to withstand the adverse space environment are presented.

LDEF Satellite Radiation Analyses

NASA Technical Reports Server (NTRS)

Armstrong, T. W.; Colborn, B. L.

1996-01-01

Model calculations and analyses have been carried out to compare with several sets of data (dose, induced radioactivity in various experiment samples and spacecraft components, fission foil measurements, and LET spectra) from passive radiation dosimetry on the Long Duration Exposure Facility (LDEF) satellite, which was recovered after almost six years in space. The calculations and data comparisons are used to estimate the accuracy of current models and methods for predicting the ionizing radiation environment in low earth orbit. The emphasis is on checking the accuracy of trapped proton flux and anisotropy models.

Analysis of Interplanetary Dust Experiment Detectors and Other Witness Plates

NASA Technical Reports Server (NTRS)

Griffis, D. P.; Wortman, J. J.

1992-01-01

The development of analytical procedures for identifying the chemical composition of residue from impacts that occurred on the Interplanetary Dust Experiment (IDE) detectors during the flight of Long Duration Exposure Facility (LDEF) and the carrying out of actual analysis on IDE detectors and other witness plates are discussed. Two papers on the following topics are presented: (1) experimental analysis of hypervelocity microparticle impact sites on IDE sensor surfaces; and (2) contaminant interfaces with secondary Ion Mass Spectrometer (SIMS) analysis of microparticle impactor residues on LDEF surfaces.

The effect of exposure duration on the subjective discomfort of aircraft cabin noise.

PubMed

Huang, Yu; Jiang, Weikang

2017-01-01

The time dependency for subjective responses to noise has been a controversial question over many years. For durations of up to 10 min, the discomfort produced by three levels of noise (ie 60, 70 and 80 dBA) was investigated in this experimental study to determine the relation of discomfort to the time duration of noise. The rate of increase in discomfort with increasing duration was 1.5 dB per doubling of exposure duration, whereas it is currently assumed to be 3 dB per doubling of exposure duration. The sound dose level (SDL) was proposed to predict the discomfort caused by noise of long duration. The combination of SDL and vibration dose value (VDV) provided more consistent estimates of the equivalent comfort contours between noise and vibration over durations from 2 to 32 s than the combination of sound exposure level and VDV or that of sound pressure level and r.m.s. acceleration. Practitioner Summary: The discomfort produced by noise of long duration can be well predicted from a new definition of sound dose level, where the discomfort increases at 1.5 dB per doubling of exposure duration.

Investigation of Teflon FEP Embrittlement on Spacecraft in Low Earth Orbit

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Smith, Daniela C.

1997-01-01

Teflon(registered trademark) FEP (fluorinated ethylene-propylene) is commonly used on exterior spacecraft surfaces in the low Earth orbit (LEO) environment for thermal control. Silverized or aluminized FEP is used for the outer layer of thermal control blankets because of its low solar absorptance and high thermal emittance. FEP is also preferred over other spacecraft polymers because of its relatively high resistance to atomic oxygen erosion. Because of its low atomic oxygen erosion yield, FEP has not been protected in the space environment. Recent, long term space exposures such as on the Long Duration Exposure Facility (LDEF, 5.8 years in space), and the Hubble Space Telescope (HST, after 3.6 years in space) have provided evidence of LEO environmental degradation of FEP. These exposures provide unique opportunities for studying environmental degradation because of the long durations and the different conditions (such as differences in altitude) of the exposures. Samples of FEP from LDEF and from HST (retrieved during its first servicing mission) have been evaluated for solar induced embrittlement and for synergistic effects of solar degradation and atomic oxygen. Micro-indenter results indicate that the surface hardness increased as the ratio of atomic oxygen fluence to solar fluence decreased for the LDEF samples. FEP multilayer insulation (MLI) retrieved from HST provided evidence of severe embrittlement on solar facing surfaces. Micro-indenter measurements indicated higher surface hardness values for these samples than LDEF samples, but the solar exposures were higher. Cracks induced during bend testing were significantly deeper for the HST samples with the highest solar exposure than for LDEF samples with similar atomic oxygen fluence to solar fluence ratios. If solar fluences are compared, the LDEF samples appear as damaged as HST samples, except that HST had deeper induced cracks. The results illustrate difficulties in comparing LEO exposed materials from different missions. Because the HST FEP appears more damaged than LDEF FEP based on depth of embrittlement, other causes for FEP embrittlement in addition to atomic oxygen and ultraviolet (UV) radiation, such as thermal effects and the possible role of soft x-ray radiation, need to be considered. FEP that was exposed to soft x-rays in a ground test facility, showed embrittlement similar to that witnessed in LEO, which indicates that the observed differences between LDEF and HST FEP might be attributed to the different soft x-ray fluences during these two missions.

The ionizing radiation environment of LDEF prerecovery predictions

NASA Technical Reports Server (NTRS)

Watts, John W., Jr.; Derrickson, James H.; Parnell, T. A.; Fishman, G. J.; Harmon, A.; Benton, E. V.; Frank, A. L.; Heinrich, Wolfgang

1991-01-01

The Long Duration Exposure Facility (LDEF) was exposed to several sources of ionizing radiation while in orbit. The principal ones were trapped belt protons and electrons, galactic cosmic rays, and albedo particles (protons and neutrons) from the atmosphere. Large solar flares in 1989 may have caused a small contribution. Prior to the recovery of the spacecraft, a number of calculations and estimates were made to predict the radiation exposure of the spacecraft and experiments. These were made to assess whether measurable radiation effects might exist, and to plan the analysis of the large number of radiation measurements available on the LDEF. Calculations and estimates of total dose, particle fluences, linear energy transfer spectra, and induced radioactivity were made. The principal sources of radiation is described, and the preflight predictions are summarized.

Space environmental effects on silvered Teflon thermal control surfaces

NASA Technical Reports Server (NTRS)

Hemminger, C. S.; Stuckey, W. K.; Uht, J. C.

1992-01-01

Cumulative space environmental effects on silver/fluorinated ethylene propylene (Ag/FEP) were a function of exposure orientation. Samples from nineteen silvered Teflon (Ag/FEP) thermal control surfaces recovered from the Long Duration Exposure Facility (LDEF) were analyzed to determine changes in this material as a function of position on the spacecraft. Although solar absorptance and infrared emittance of measured thermal blanket specimens are relatively unchanged from control specimen values, significant changes in surface morphology, composition, and chemistry were observed. We hypothesize that the FEP surfaces on the LDEF are degraded by UV radiation at all orientations, but that the damaged material has been removed by erosion from the blankets exposed to atomic oxygen flux and that contamination is masking the damage in some areas on the trays flanking the trailing edge.

LDEF materials data analysis: Representative examples

NASA Technical Reports Server (NTRS)

Pippin, Gary; Crutcher, Russ

1993-01-01

Part of the philosophy which guided the examination of hardware from the Long Duration Exposure Facility (LDEF) was that materials present at multiple locations should have fairly high priority for investigation. Properties of such materials were characterized as a function of exposure conditions to obtain as much data as possible for predicting performance lifetimes. Results from examination of several materials from interior locations of LDEF, selected measurements on silverized teflon blanket specimens, and detailed measurements on the copper grounding strap from tray D11 are summarized. Visual observations of interior locations of LDEF made during deintegration at KSC showed apparent changes in particular specimens. This inspection lead to testing of selected nylon clamps, fiberglass shims, and heat shrink tubing from wire harness clamps, and visually discolored silver coated hex nuts.

Long Duration Exposure Facility (LDEF)

NASA Technical Reports Server (NTRS)

1984-01-01

The Long Duration Exposure Facility (LDEF) was designed by the Marshall Space Flight Center (MSFC) to test the performance of spacecraft materials, components, and systems that have been exposed to the environment of micrometeoroids and space debris for an extended period of time. The LDEF proved invaluable to the development of future spacecraft and the International Space Station (ISS). The LDEF carried 57 science and technology experiments, the work of more than 200 investigators. MSFC`s experiments included: Trapped Proton Energy Determination to determine protons trapped in the Earth's magnetic field and the impact of radiation particles; Linear Energy Transfer Spectrum Measurement Experiment which measures the linear energy transfer spectrum behind different shielding configurations; Atomic oxygen-Simulated Out-gassing, an experiment that exposes thermal control surfaces to atomic oxygen to measure the damaging out-gassed products; Thermal Control Surfaces Experiment to determine the effects of the near-Earth orbital environment and the shuttle induced environment on spacecraft thermal control surfaces; Transverse Flat-Plate Heat Pipe Experiment, to evaluate the zero-gravity performance of a number of transverse flat plate heat pipe modules and their ability to transport large quantities of heat; Solar Array Materials Passive LDEF Experiment to examine the effects of space on mechanical, electrical, and optical properties of lightweight solar array materials; and the Effects of Solar Radiation on Glasses. Launched aboard the Space Shuttle Orbiter Challenger's STS-41C mission April 6, 1984, the LDEF remained in orbit for five years until January 1990 when it was retrieved by the Space Shuttle Orbiter Columbia STS-32 mission and brought back to Earth for close examination and analysis.

42 CFR 488.454 - Duration of remedies.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 5 2010-10-01 2010-10-01 false Duration of remedies. 488.454 Section 488.454... Compliance for Long-Term Care Facilities with Deficiencies § 488.454 Duration of remedies. (a) Except as specified in paragraphs (b) and (d) of this section, alternative remedies continue until— (1) The facility...

42 CFR 488.454 - Duration of remedies.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 5 2011-10-01 2011-10-01 false Duration of remedies. 488.454 Section 488.454... Compliance for Long-Term Care Facilities with Deficiencies § 488.454 Duration of remedies. (a) Except as specified in paragraphs (b) and (d) of this section, alternative remedies continue until— (1) The facility...

Effects of low Earth orbit environment on the Long Duration Exposure Facility thermal control coatings

NASA Technical Reports Server (NTRS)

Sampair, Thomas R.; Berrios, William M.

1992-01-01

One of the benefits of the Long Duration Exposure Facility (LDEF) was the opportunity to study the before and after effects of low earth orbit space environment on the spacecraft thermal control coatings. Since the LDEF's thermal control was totally passive by design, the selection of the external surface absorptivity to emissivity ratio (alpha/epsilon) and the ability for the coating to retain the alpha/epsilon over time was an important consideration in the thermal design of the LDEF. The primary surface coating chosen for the LDEF structure was clear chromic anodized aluminum with an average design alpha/epsilon of 0.32/0.16. External surface absorptivity (alpha) and emissivity (epsilon) were measured on all intercostals, longerons, tray mounting flanges, thermal control panels, and a limited number of experiment surface coatings after the experiment trays were removed from the LDEF structure. All surface alpha/epsilon measurements were made using portable hand held infrared and solar spectrum reflectometers. The absorptivity measurements were taken with a Devices and Services SSR-ER version 5.0 solar spectra reflectometer which has a stated uncertainty of +/- 0.01, and all normal emissivity measurements were made using the Gier Dunkle DB-100 infrared reflectometer also with a stated uncertainty of +/- 0.01. Both instruments were calibrated in the laboratory by LaRC instrumentation personnel before being used in the field at KSC. A combined total of 733 measurements were taken on the anodized aluminum hardware which included the structure (intercostals, longerons, and center ring), earth and space end thermal control panels, and experiment tray mounting flanges. The facility thermal control coatings measured in this survey cover 33 percent of the total exposed LDEF surface area. To correlate low earth orbit environmental effects on the anodized coatings, measurements were taken in both exposed and unexposed surfaces and compared to quality assurance (QA) measurements taken on the new surfaces at the time of hardware fabrication in 1978. The results of investigation are presented.

Performance of selected polymeric materials on LDEF

NASA Technical Reports Server (NTRS)

Young, Philip R.; Slemp, Wayne S.; Stein, Bland A.

1993-01-01

The NASA Long Duration Exposure Facility (LDEF) provided a unique environmental exposure of a wide variety of materials for potential advanced spacecraft application. This paper examines the molecular level response of selected polymeric materials which flew onboard this vehicle. Polymers include epolyimide, polysulfone, and polystyrene film and polyimide, polysulfone, and epoxy matrix resin/graphite fiber reinforced composites. Several promising experimental films were also studied. Most specimens received 5.8 years of low Earth orbital (LEO) exposure on LDEF. Several samples received on 10 months of exposure. Chemical characterization techniques included ultraviolet-visible and infrared spectroscopy, thermal analysis, x-ray photoelectron spectroscopy, and selected solution property measurements. Results suggest that many molecular level effects present during the first 10 months of exposure were not present after 5.8 years of exposure for specimens on or near Row 9. Increased AO fluence near the end of the mission likely eroded away much environmentally induced surface phenomena. The objective of this work is to provide fundamental information for use in improving the performance of polymeric materials for LEO application. A secondary objective is to gain an appreciation for the constraints and limitations of results from LDEF polymeric materials experiments.

Induced radioactivity in LDEF components

NASA Technical Reports Server (NTRS)

Harmon, B. A.; Fishman, G. J.; Parnell, T. A.; Laird, C. E.

1991-01-01

The systematics of induced radioactivity on the Long Duration Exposure Facility (LDEF) were studied in a wide range of materials using low level background facilities for detection of gamma rays. Approx. 400 samples of materials processed from structural parts of the spacecraft, as well as materials from onboard experiments, were analyzed at national facilities. These measurements show the variety of radioisotopes that are produced with half-lives greater than 2 wks, most of which are characteristic of proton induced reactions above 20 MeV. For the higher activity, long lived isotopes, it was possible to map the depth and directional dependences of the activity. Due to the stabilized configuration of the LDEF, the induced radioactivity data clearly show contributions from the anisotropic trapped proton flux in the South Atlantic Anomaly. This effect is discussed, along with evidence for activation by galactic protons and thermal neutrons. The discovery of Be-7 was made on leading side parts of the spacecraft, although this was though not to be related to the in situ production of radioisotopes from external particle fluxes.

LDEF polymeric materials: A summary of Langley characterization

NASA Technical Reports Server (NTRS)

Young, Philip R.; Slemp, Wayne S.; Whitley, Karen S.; Kalil, Carol R.; Siochi, Emilie J.; Shen, James Y.; Chang, A. C.

1995-01-01

The NASA Long Duration Exposure Facility (LDEF) enabled the exposure of a wide variety of materials to the low earth orbit (LEO) environment. This paper provides a summary of research conducted at the Langley Research Center into the response of selected LDEF polymers to this environment. Materials examined include graphite fiber reinforced epoxy, polysulfone, and additional polyimide matrix composites, films of FEP Teflon, Kapton, several experimental high performance polyimides, and films of more traditional polymers such as poly(vinyl toluene) and polystyrene. Exposure duration was either 10 months or 5.8 years. Flight and control specimens were characterized by a number of analytical techniques including ultraviolet-visible and infrared spectroscopy, thermal analysis, scanning electron and scanning tunneling microscopy, x-ray photoelectron spectroscopy, and, in some instances, selected solution property measurements. Characterized effects were found to be primarily surface phenomena. These effects included atomic oxygen-induced erosion of unprotected surfaces and ultraviolet-induced discoloration and changes in selected molecular level parameters. No gross changes in molecular structure or glass transition temperature were noted. The intent of this characterization is to increase our fundamental knowledge of space environmental effects as an aid in developing new and improved polymers for space application. A secondary objective is to develop benchmarks to enhance our methodology for the ground-based simulation of environmental effects so that polymer performance in space can be more reliably predicted.

Associations of Frequency and Duration of Patient-Doctor Contact in Hemodialysis Facilities with Mortality

PubMed Central

Karaboyas, Angelo; Robinson, Bruce M.; Li, Yun; Fukuhara, Shunichi; Bieber, Brian A.; Rayner, Hugh C.; Andreucci, Vittorio E.; Pisoni, Ronald L.; Port, Friedrich K.; Morgenstern, Hal; Akizawa, Tadao; Saran, Rajiv

2013-01-01

It is unknown whether regular patient-doctor contact (PDC) contributes to better outcomes for patients undergoing hemodialysis. Here, we analyzed the associations between frequency and duration of PDC during hemodialysis treatments with clinical outcomes among 24,498 patients from 778 facilities in the international Dialysis Outcomes and Practice Patterns Study (DOPPS). The typical facility PDC frequency, estimated by facility personnel, was high (more than once per week) for 55% of facilities, intermediate (once per week) for 24%, and low (less than once per week) for 21%. The mean ± SD estimated duration of a typical interaction between patient and physician was 7.7±5.6 minutes. PDC frequency and duration varied across DOPPS phases and countries; the proportion of facilities with high PDC frequency was 17% in the United States and 73% across the other countries. Compared with high PDC frequency, the adjusted hazard ratio (HR) for all-cause mortality was 1.06 (95% confidence interval [CI], 0.96 to 1.17) for intermediate PDC frequency and 1.11 (95% CI, 1.01 to 1.23) for low PDC frequency (P=0.03 for trend). Furthermore, each 5-minutes-shorter duration of PDC was associated with a 5% higher risk for death, on average (HR, 1.05; 95% CI, 1.01 to 1.09), adjusted for PDC frequency and other covariates. Multivariable analyses also suggested modest inverse associations between both PDC frequency and duration with hospitalization but not with kidney transplantation. Taken together, these results suggest that policies supporting more frequent and longer duration of PDC may improve patient outcomes in hemodialysis. PMID:23886592

Evaluation of exposure-response relationships for health effects of microbial bioaerosols - A systematic review.

PubMed

Walser, Sandra M; Gerstner, Doris G; Brenner, Bernhard; Bünger, Jürgen; Eikmann, Thomas; Janssen, Barbara; Kolb, Stefanie; Kolk, Annette; Nowak, Dennis; Raulf, Monika; Sagunski, Helmut; Sedlmaier, Nadja; Suchenwirth, Roland; Wiesmüller, Gerhard; Wollin, Klaus-Michael; Tesseraux, Irene; Herr, Caroline E W

2015-10-01

Studies suggest adverse health effects following exposure to bioaerosols in the environment and in particular at workplaces. However, there is still a lack of health-related exposure limits based on toxicological or epidemiological studies from environmental health or from the working environment. The aim of this study was to derive health-based exposure limits for bioaerosols that can protect the general population as group "at risk" via environmental exposure using analysis of peer-reviewed studies related to occupational medicine, indoor air and environmental health. The derivation of exposure limits should be conducted by the members of a bioaerosol expert panel according to established toxicological criteria. A systematic review was performed in Medline (PubMed) including studies containing both data on exposure measurements and observed health outcomes. In addition, literature recommended by the experts was considered. A comprehensive search strategy was generated and resulted in a total of n=1569 studies in combination with the literature recommendations. Subsequently, abstracts were screened using defined exclusion criteria yielding a final number of n=44 studies. A standardized extraction sheet was used to combine data on health effects and exposure to different bioaerosols. After full-text screening and extraction according to the defined exclusion criteria n=20 studies were selected all related to occupational exposures comprising the working areas wood processing, farming, waste processing and others. These studies were analyzed in collaboration with the bioaerosol expert network in terms of suitability for derivation of health-related exposure limits. The bioaerosol expert network concluded that none of the analyzed studies provided suitable dose-response relationships for derivation of exposure limits. The main reasons were: (1) lack of studies with valid dose-response data; (2) diversity of employed measuring methods for microorganisms and bioaerosol-emitting facilities; (3) heterogeneity of health effects; (4) insufficient exposure assessment. However, several indicator parameters and exposure concentrations could be identified for different bioaerosol-emitting facilities. Nevertheless, health-related exposure limits are urgently needed especially in approval procedures of facilities like composting plants or livestock farms emitting bioaerosols in the neighbourhood of residents. In the regulatory toxicology framework, it is common to use animal experimental studies for derivation of general exposure limits if appropriate environmental epidemiological studies on harmful substances are lacking. This might be another possibility to obtain health-related exposure limits for specific bioaerosol parameters. Furthermore, we recommend to use suitable measurable outcome parameters related to bioaerosols; to measure bioaerosols according to a protocol representative for exposure pattern and duration at the particular work place; to develop standardized detection methods for indicator parameters; to combine different detection methods to compensate for the limitations of each method; to apply new analysis methods to identify the real risk potential. Copyright © 2015 Elsevier GmbH. All rights reserved.

Induced radioactivity of LDEF materials and structural components

NASA Technical Reports Server (NTRS)

Harmon, B. A.; Laird, C. E.; Fishman, G. J.; Parnell, T. A.; Camp, D. C.; Frederick, C. E.; Hurley, D. L.; Lindstrom, D. J.; Moss, C. E.; Reedy, R. C.;

Estimating pediatric general anesthesia exposure: Quantifying duration and risk.

PubMed

Bartels, Devan Darby; McCann, Mary Ellen; Davidson, Andrew J; Polaner, David M; Whitlock, Elizabeth L; Bateman, Brian T

2018-05-02

Understanding the duration of pediatric general anesthesia exposure in contemporary practice is important for identifying groups at risk for long general anesthesia exposures and designing trials examining associations between general anesthesia exposure and neurodevelopmental outcomes. We performed a retrospective cohort analysis to estimate pediatric general anesthesia exposure duration during 2010-2015 using the National Anesthesia Clinical Outcomes Registry. A total of 1 548 021 pediatric general anesthetics were included. Median general anesthesia duration was 57 minutes (IQR: 28-86) with 90th percentile 145 minutes. Children aged <1 year had the longest median exposure duration (79 minutes, IQR: 39-119) with 90th percentile 210 minutes, and 13.7% of this very young cohort was exposed for >3 hours. High ASA physical status and care at a university hospital were associated with longer exposure times. While the vast majority (94%) of children undergoing general anesthesia are exposed for <3 hours, certain groups may be at increased risk for longer exposures. These findings may help guide the design of future trials aimed at understanding neurodevelopmental impact of prolonged exposure in these high-risk groups. © 2018 John Wiley & Sons Ltd.

Assessment of management policies and practices for occupational exposure to bloodborne pathogens in dialysis facilities.

PubMed

Mbaeyi, Chukwuma; Panlilio, Adelisa L; Hobbs, Cynthia; Patel, Priti R; Kuhar, David T

2012-10-01

Occupational exposure management is an important element in preventing the transmission of bloodborne pathogens in health care settings. In 2008, the US Centers for Disease Control and Prevention conducted a survey to assess procedures for managing occupational bloodborne pathogen exposures in outpatient dialysis facilities in the United States. A cross-sectional survey of randomly selected outpatient dialysis facilities. 339 outpatient dialysis facilities drawn from the 2006 US end-stage renal disease database. Hospital affiliation (free-standing vs hospital-based facilities), profit status (for-profit vs not-for-profit facilities), and number of health care personnel (≥100 vs <100 health care personnel). Exposures to hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV); provision of HBV and HIV postexposure prophylaxis. We calculated the proportion of facilities reporting occupational bloodborne pathogen exposures and offering occupational exposure management services. We analyzed bloodborne pathogen exposures and provision of postexposure prophylaxis by facility type. Nearly all respondents (99.7%) had written policies and 95% provided occupational exposure management services to health care personnel during the daytime on weekdays, but services were provided infrequently during other periods of the week. Approximately 10%-15% of facilities reported having HIV, HBV, or HCV exposures in health care personnel in the 12 months prior to the survey, but inconsistencies were noted in procedures for managing such exposures. Despite 86% of facilities providing HIV prophylaxis for exposed health care personnel, only 37% designated a primary HIV postexposure prophylaxis regimen. For-profit and free-standing facilities reported fewer exposures, but did not as reliably offer HBV prophylaxis or have a primary HIV postexposure prophylaxis regimen relative to not-for-profit and hospital-based facilities. The survey response rate was low (37%) and familiarity of individuals completing the survey with facility policies or national guidelines could not be ascertained. Significant improvements are required in the implementation of guidelines for managing occupational exposures to bloodborne pathogens in outpatient dialysis facilities. Published by Elsevier Inc.

What LDEF means for development and testing of materials

NASA Technical Reports Server (NTRS)

Whitaker, Ann F.; Stuckey, Wayne K.; Stein, Bland A.

1993-01-01

The Long Duration Exposure Facility (LDEF) served as the ultimate laboratory to provide combined space environmental effects on materials. The LDEF structure and its 57 experiments contained an estimated 12,000 to 14,000 specimens of materials and materials processes. It not only provided information about the resistance of these materials to the space environment but gives us direction into future needs for spacecraft materials development and testing. This paper provides an overview of the materials effects observed on the satellite and suggests recommendations for the future work in space-qualified materials development and space environmental simulation.

LDEF Retrieval over the Namib Desert, Namibia, Africa

NASA Image and Video Library

1990-01-20

STS032-85-029 (12 Jan. 1990) --- (ORIENT PHOTO WITH COLUMBIA'S CARGO BAY IN LOWER CENTER). This 70mm frame was taken during a battery of documentary photographs of the recently-recaptured Long Duration Exposure Facility (LEDF). The Atlantic Coast of Namibia serves as a backdrop for the colorful scene. After five-and-one half years orbiting Earth, LDEF was retrieved by STS-32 crewmembers and brought back home at the end of the eleven-day mission for scientific observation. The bus-sized spacecraft was held in the grasp of Columbia's remote manipulator system (RMS) end effector during the survey.

National Space Transportation Systems Program mission report

NASA Technical Reports Server (NTRS)

Collins, M. A., Jr.; Aldrich, A. D.; Lunney, G. S.

1984-01-01

The STS 41-C National Space Transportation Systems Program Mission Report contains a summary of the major activities and accomplishments of the eleventh Shuttle flight and fifth flight of the OV-099 vehicle, Challenger. Also summarized are the significant problems that occurred during STS 41-C, and a problem tracking list that is a complete list of all problems that occurred during the flight. The major objectives of flight STS 41-C were to successfully deploy the LDEF (long duration exposure facility) and retrieve, repair and redeploy the SMM (Solar Maximum Mission) spacecraft, and perform functions of IMAX and Cinema 360 cameras.

Data bases for LDEF results

NASA Technical Reports Server (NTRS)

Bohnhoff-Hlavacek, Gail

1993-01-01

The Long Duration Exposure Facility (LDEF) carried 57 experiments and 10,000 specimens for some 200 LDEF experiment investigators. The external surface of LDEF had a large variety of materials exposed to the space environment which were tested preflight, during flight, and post flight. Thermal blankets, optical materials, thermal control paints, aluminum, and composites are among the materials flown. The investigations have produced an abundance of analysis results. One of the responsibilities of the Boeing Support Contract, Materials and Systems Special Investigation Group, is to collate and compile that information into an organized fashion. The databases developed at Boeing to accomplish this task is described.

An active thermal control surfaces experiment. [spacecraft temperature determination

NASA Technical Reports Server (NTRS)

Wilkes, D. R.; Brown, M. J.

1979-01-01

An active flight experiment is described that has the objectives to determine the effects of the low earth natural environment and the Shuttle induced environment on selected thermal control and optical surfaces. The optical and thermal properties of test samples will be measured in-situ using an integrating sphere reflectrometer and using calorimetric methods. This experiment has been selected for the Long Duration Exposure Facility (LDEF) flight which will be carried to orbit by the NASA Space Shuttle. The LDEF will remain in orbit to be picked up by a later Shuttle mission and returned for postflight evaluation.

Physiological performance of the intertidal Manila clam (Ruditapes philippinarum) to long-term daily rhythms of air exposure

PubMed Central

Yin, Xuwang; Chen, Peng; Chen, Hai; Jin, Wen; Yan, Xiwu

2017-01-01

Intertidal organisms, especially the sessile species, often experience long-term periodic air exposure during their lives. Learning the biochemical and physiological responses of intertidal organisms to long-term periodic air exposure and the relationship to duration of air exposure provides insight into adaptation to this variably stressful environment. We studied the Manila clam, Ruditapes philippinarum, an important species in world aquaculture, as a model to evaluate survival, growth, lipid composition, oxygen consumption, oxidative damage, and antioxidant enzyme activity in relation to the duration of air exposure in a long-term (60 days) laboratory study of varying durations of periodic emersion and re-immersion. Our results show: (1) clams undergoing a longer period of air exposure had lower survival and growth compared to those given a shorter exposure, (2) levels of oxidative damage and activities of antioxidant enzymes were higher in all air exposure treatments, but did not increase with duration of air exposure, and (3) the content of docosahexaenoic acid increased with duration of air exposure. Our results can largely be interpreted in the context of the energy expenditure by the clams caused by aerobic metabolism during the daily cycle of emersion and re-immersion and the roles of docosahexaenoic acid against oxidative stress. PMID:28128354

The Effect of Exposure Duration on Visual Character Identification in Single, Whole, and Partial Report

ERIC Educational Resources Information Center

Petersen, Anders; Andersen, Tobias S.

2012-01-01

The psychometric function of single-letter identification is typically described as a function of stimulus intensity. However, the effect of stimulus exposure duration on letter identification remains poorly described. This is surprising because the effect of exposure duration has played a central role in modeling performance in whole and partial…

Long Duration Exposure Facility (LDEF) preliminary findings: LEO space effects on the space plasma-voltage drainage experiment

NASA Technical Reports Server (NTRS)

Blakkolb, Brian K.; Yaung, James Y.; Henderson, Kelly A.; Taylor, William W.; Ryan, Lorraine E.

1992-01-01

The Space Plasma-High Voltage Drainage Experiment (SP-HVDE) provided a unique opportunity to study long term space environmental effects on materials because it was comprised of two identical experimental trays; one tray located on the ram facing side (D-10), and the other on the wake facing side (B-4) of the LDEF. This configuration allows for the comparison of identical materials exposed to two distinctly different environments. The purpose of this work is to document an assessment of the effects of five and three quarters years of low Earth orbital space exposure on materials comprising the SP-HVDE (experiment no. A0054). The findings of the materials investigation reported focus on atomic oxygen effects, micrometeor and debris impact site documentation, thermal property measurements, and environmentally induced contamination.

Toxicological safeguards in the manned Mars missions

NASA Technical Reports Server (NTRS)

Coleman, Martin E.

1986-01-01

Safeguards against toxic chemical exposures during manned Mars missions (MMMs) will be important for the maintenance of crew health and the accomplishment of mission objectives. Potential sources include offgassing, thermodegradation or combustion of materials, metabolic products of crew members, and escape of chemical from containment. Spacecraft maximum allowable concentration (SMAC) limits will have to be established for potential contaminants during the MMMs. The following factors will be used in establishing these limits: duration of mission, simultaneous exposure to other contaminants, deconditioning of crew members after long periods of reduced gravity, and simultaneous exposure to ionizing radiation. Atmospheric contaminant levels in all compartments of the transit spacecraft and Manned Mars Station (MMS) will be monitored at frequent intervals with a real time analyzer. This analyzer will be highly automated, requiring minimal crew time and expertise. The atmospheric analyzer will find other usages during the MMMs such as analyzing Martian atmospheres and soils, exhaled breath and body fluids of crew members, and reaction products in chemical processing facilities.

Revised prediction of LDEF exposure to trapped protons

NASA Technical Reports Server (NTRS)

Watts, John W.; Armstrong, T. W.; Colborn, B. L.

1993-01-01

The Long Duration Exposure Facility (LDEF) spacecraft flew in a 28.5 deg inclination circular orbit with an altitude in the range from 319.4 to 478.7 km. For this orbital altitude and inclination, two components contribute most of the penetrating charge particle radiation encountered - the galactic cosmic rays and the geomagnetically trapped Van Allen protons. Where shielding is less than 1.0 g/sq cm geomagnetically trapped electrons make a significant contribution. The 'Vette' models together with the associated magnetic field models and the solar conditions were used to obtain the trapped electron and proton omnidirectional fluences reported previously. Results for directional proton spectra using the MSFC anisotropy model for solar minimum and 463 km altitude (representative for the LDEF mission) were also reported. The directional trapped proton flux as a function of mission time is presented considering altitude and solar activity variation during the mission. These additional results represent an extension of previous calculations to provide a more definitive description of the LDEF trapped proton exposure.

Effects of Y27632 on aqueous humor outflow facility with changes in hydrodynamic pattern and morphology in human eyes.

PubMed

Yang, Chen-Yuan Charlie; Liu, Ye; Lu, Zhaozeng; Ren, Ruiyi; Gong, Haiyan

2013-08-28

To determine the effect of Y27632, a Rho-kinase inhibitor on aqueous outflow facility, flow pattern, and juxtacanalicular tissue (JCT)/trabecular meshwork (TM) morphology in human eyes. Sixteen enucleated human eyes were perfused with PBS plus glucose (GPBS) at 15 mm Hg to establish the baseline outflow facility. Six eyes were perfused for short-duration (30 minute) with either 50 μM Y27632 or GPBS (n = 3 per group). Ten eyes were perfused for long duration (3 hours) with either 50 μM Y27632 or GPBS (n = 5 per group). Outflow pattern was labeled using fluorescent microspheres, and effective filtration length (EFL) was measured. Morphologic changes and their relationship to EFL and facility were analyzed. Outflow facility significantly increased after short-duration perfusion with Y27632 compared with its own baseline (P = 0.03), but did not reach statistical significance compared with its controls (P = 0.07). Outflow facility (P = 0.01) and EFL (P < 0.05) were significantly increased after long-duration perfusion with Y27632 compared with its controls. Increases in outflow facility and EFL demonstrated a positive correlation. Morphologically, the TM and JCT of high-tracer regions were more expanded compared with low-tracer regions. A significant increase in JCT thickness was found in the long-duration Y27632 group compared with its control group (10.0 vs. 8.0 μm, P < 0.01). Y27632 increases outflow facility in human eyes. This increase correlates positively with an increase in EFL, which is associated with an increased expansion in the JCT. Our data suggest that EFL could serve as a novel parameter to correlate with outflow facility.

Hypervelocity impact facility for simulating materials exposure to impact by space debris

NASA Technical Reports Server (NTRS)

Rose, M. F.; Best, S.; Chaloupka, T.; Stephens, B.; Crawford, G.

1993-01-01

As a result of man's venturing into space, the local debris contributed by his presence exceeds, at some orbital altitudes, that of the natural component. Man's contribution ranges from fuel residue to large derelect satellites that weigh many kilograms. Current debris models are able to predict the growth of the problem and suggest that spacecraft must employ armor or bumper shields for some orbital altitudes now, and that, the problem will become worse as a function of time. The practical upper limit to the velocity distribution is on the order of 40 km/s and is associated with the natural environment. The maximum velocity of the man-made component is in the 14-16 km/s range. The Long Duration Exposure Facility (LDEF) has verified that the 'high probability of impact' particles are in the microgram to milligram range. These particles can have significant effects on coatings, insulators, and thin metallic layers. The surface of thick materials becomes pitted and the local debris component is enhanced by ejecta from the debris spectrum in a controlled environment. The facility capability is discussed in terms of drive geometry, energetics, velocity distribution, diagnostics, and projectile/debris loading. The facility is currently being used to study impact phenomena on Space Station Freedom's solar array structure, other solar array materials, potential structural materials for use in the station, electrical breakdown in the space environment, and as a means of clarifying or duplicating the impact phenomena on the LDEF surfaces. The results of these experiments are described in terms of the mass/velocity distribution incident on selected samples, crater dynamics, and sample geometry.

Collection, analysis, and archival of LDEF activation data

NASA Technical Reports Server (NTRS)

Laird, C. E.; Harmon, B. A.; Fishman, G. J.; Parnell, T. A.

1993-01-01

The study of the induced radioactivity of samples intentionally placed aboard the Long Duration Exposure Facility (LDEF) and samples obtained from the LDEF structure is reviewed. The eight laboratories involved in the gamma-ray counting are listed and the scientists and the associated counting facilities are described. Presently, most of the gamma-ray counting has been completed and the spectra are being analyzed and corrected for efficiency and self absorption. The acquired spectra are being collected at Eastern Kentucky University for future reference. The results of these analyses are being compiled and reviewed for possible inconsistencies as well as for comparison with model calculations. These model calculations are being revised to include the changes in trapped-proton flux caused by the onset of the period of maximum solar activity and the rapidly decreasing spacecraft orbit. Tentative plans are given for the storage of the approximately 1000 gamma-ray spectra acquired in this study and the related experimental data.

International Space University variable gravity research facility design

NASA Astrophysics Data System (ADS)

Bailey, Sheila G.; Chiaramonte, Francis P.; Davidian, Kenneth J.

1994-03-01

A manned mission to Mars will require long travel times between Earth and Mars. However, exposure to long-duration zero gravity is known to be harmful to the human body. Some of the harmful effects are loss of heart and lung capacity, inability to stand upright, muscular weakness, and loss of bone calcium. A variable gravity research facility (VGRF) that will be placed in low Earth orbit (LEO) was designed by students of the International Space University 1989 Summer Session held in Strasbourg, France, to provide a testbed for conducting experiments in the life and physical sciences in preparation for a mission to Mars. This design exercise was unique because it addressed all aspects concerning a large space project. This report describes the VGRF design that was developed by international participants specializing in the following areas: the politics of international cooperation; engineering, architecture; in-space physiological, materials, and life science experimentation; data communications; and business and management.

The International Space University's variable gravity research facility design

NASA Astrophysics Data System (ADS)

Bailey, Sheila G.; Chiaramonte, Francis P.; Davidian, Kenneth J.

1991-09-01

A manned mission to Mars will require long travel times between Earth and Mars. However, exposure to long-duration zero gravity is known to be harmful to the human body. Some of the harmful effects are loss of heart and lung capacity, inability to stand upright, muscular weakness and loss of bone calcium. A variable gravity research facility (VGRF) that would be placed in low Earth orbit (LEO) was designed by students of the International Space University 1989 Summer Session held in Strasbourg, France, to provide a testbed for conducting experiments in the life and physical sciences in preparation for a mission to Mars. This design exercise was unique because it addressed all aspects concerning a large space project. The VGRF design was described which was developed by international participants specializing in the following areas: the politics of international cooperation, engineering, architecture, in-space physiology, material and life science experimentation, data communications, business, and management.

The International Space University's variable gravity research facility design

NASA Technical Reports Server (NTRS)

Bailey, Sheila G.; Chiaramonte, Francis P.; Davidian, Kenneth J.

1991-01-01

A manned mission to Mars will require long travel times between Earth and Mars. However, exposure to long-duration zero gravity is known to be harmful to the human body. Some of the harmful effects are loss of heart and lung capacity, inability to stand upright, muscular weakness and loss of bone calcium. A variable gravity research facility (VGRF) that would be placed in low Earth orbit (LEO) was designed by students of the International Space University 1989 Summer Session held in Strasbourg, France, to provide a testbed for conducting experiments in the life and physical sciences in preparation for a mission to Mars. This design exercise was unique because it addressed all aspects concerning a large space project. The VGRF design was described which was developed by international participants specializing in the following areas: the politics of international cooperation, engineering, architecture, in-space physiology, material and life science experimentation, data communications, business, and management.

Factors associated with self-estimated work ability and musculoskeletal symptoms among male and female workers in cooled food-processing facilities.

PubMed

Sormunen, Erja; Remes, Jouko; Hassi, Juhani; Pienimäki, Tuomo; Rintamäki, Hannu

2009-07-01

This questionnaire study evaluates how work ability and musculoskeletal symptoms associate with physical work factors and individual characteristics of the workers in cooled food-processing facilities. A total of 1,117 workers (response rate 85%) responded to the study. Poor work ability was significantly associated with longer work duration, experience of draught at the workplace, absence from work due to health reasons, and physical inactivity during free time. The amount of local cooling experienced was significantly associated with the risk for musculoskeletal symptoms in the neck-shoulder region, shoulders, wrists and lower back. Additionally, female gender, longer work duration and poor work ability were associated with the increased prevalence of the symptoms. The prevalence of musculoskeletal symptoms was significantly higher among older employees (40 to 64 yr) than among younger employees (18 to 39 yr) for all regions except wrists. Cold discomfort and unpleasant sensations due to the physical factors of work were significantly more common among females than males. The results showed that, in addition to individual characteristics of workers, factors related to work in a cool environment (experience of draught and cooling and long exposure to cold) are associated with poor work ability and musculoskeletal symptoms.

Creation of a retrospective job-exposure matrix using surrogate measures of exposure for a cohort of US career firefighters from San Francisco, Chicago and Philadelphia

PubMed Central

Dahm, Matthew M; Bertke, Stephen; Allee, Steve; Daniels, Robert D

2015-01-01

Objectives To construct a cohort-specific job-exposure matrix (JEM) using surrogate metrics of exposure for a cancer study on career firefighters from the Chicago, Philadelphia and San Francisco Fire Departments. Methods Departmental work history records, along with data on historical annual fire-runs and hours, were collected from 1950 to 2009 and coded into separate databases. These data were used to create a JEM based on standardised job titles and fire apparatus assignments using several surrogate exposure metrics to estimate firefighters’ exposure to the combustion byproducts of fire. The metrics included duration of exposure (cumulative time with a standardised exposed job title and assignment), fire-runs (cumulative events of potential fire exposure) and time at fire (cumulative hours of potential fire exposure). Results The JEM consisted of 2298 unique job titles alongside 16 174 fire apparatus assignments from the three departments, which were collapsed into 15 standardised job titles and 15 standardised job assignments. Correlations were found between fire-runs and time at fires (Pearson coefficient=0.92), duration of exposure and time at fires (Pearson coefficient=0.85), and duration of exposure and fire-runs (Pearson coefficient=0.82). Total misclassification rates were found to be between 16–30% when using duration of employment as an exposure surrogate, which has been traditionally used in most epidemiological studies, compared with using the duration of exposure surrogate metric. Conclusions The constructed JEM successfully differentiated firefighters based on gradient levels of potential exposure to the combustion byproducts of fire using multiple surrogate exposure metrics. PMID:26163543

Creation of a retrospective job-exposure matrix using surrogate measures of exposure for a cohort of US career firefighters from San Francisco, Chicago and Philadelphia.

PubMed

Dahm, Matthew M; Bertke, Stephen; Allee, Steve; Daniels, Robert D

2015-09-01

To construct a cohort-specific job-exposure matrix (JEM) using surrogate metrics of exposure for a cancer study on career firefighters from the Chicago, Philadelphia and San Francisco Fire Departments. Departmental work history records, along with data on historical annual fire-runs and hours, were collected from 1950 to 2009 and coded into separate databases. These data were used to create a JEM based on standardised job titles and fire apparatus assignments using several surrogate exposure metrics to estimate firefighters' exposure to the combustion byproducts of fire. The metrics included duration of exposure (cumulative time with a standardised exposed job title and assignment), fire-runs (cumulative events of potential fire exposure) and time at fire (cumulative hours of potential fire exposure). The JEM consisted of 2298 unique job titles alongside 16,174 fire apparatus assignments from the three departments, which were collapsed into 15 standardised job titles and 15 standardised job assignments. Correlations were found between fire-runs and time at fires (Pearson coefficient=0.92), duration of exposure and time at fires (Pearson coefficient=0.85), and duration of exposure and fire-runs (Pearson coefficient=0.82). Total misclassification rates were found to be between 16-30% when using duration of employment as an exposure surrogate, which has been traditionally used in most epidemiological studies, compared with using the duration of exposure surrogate metric. The constructed JEM successfully differentiated firefighters based on gradient levels of potential exposure to the combustion byproducts of fire using multiple surrogate exposure metrics. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Secondhand smoke exposure in the workplace.

PubMed

Skeer, Margie; Cheng, Debbie M; Rigotti, Nancy A; Siegel, Michael

2005-05-01

Currently, there is little understanding of the relationship between the strength of workplace smoking policies and the likelihood and duration, not just the likelihood, of exposure to secondhand smoke at work. This study assessed self-reported exposure to secondhand smoke at work in hours per week among a cross-sectional sample of 3650 Massachusetts adults who were employed primarily at a single worksite outside the home that was not mainly outdoors. The sample data were from a larger longitudinal study designed to examine the effect of community-based tobacco control interventions on adult and youth smoking behavior. Participants were identified through a random-digit-dialing telephone survey. Multiple logistic regression and zero-inflated negative binomial regression models were used to estimate the independent effect of workplace smoking policies on the likelihood and duration of exposure to secondhand smoke. Compared to employees whose workplace banned smoking completely, those whose workplace provided designated smoking areas had 2.9 times the odds of being exposed to secondhand smoke and 1.74 times the duration of exposure, while those with no restrictions had 10.27 times the odds of being exposed and 6.34 times the duration of exposure. Workplace smoking policies substantially reduce the likelihood of self-reported secondhand smoke exposure among employees in the workplace and also greatly affect the duration of exposure.

Environmental Enrichment Duration Differentially Affects Behavior and Neuroplasticity in Adult Mice.

PubMed

Leger, Marianne; Paizanis, Eleni; Dzahini, Kwamivi; Quiedeville, Anne; Bouet, Valentine; Cassel, Jean-Christophe; Freret, Thomas; Schumann-Bard, Pascale; Boulouard, Michel

2015-11-01

Environmental enrichment is a powerful way to stimulate brain and behavioral plasticity. However the required exposure duration to reach such changes has not been substantially analyzed. We aimed to assess the time-course of appearance of the beneficial effects of enriched environment. Thus, different behavioral tests and neurobiological parameters (such as neurogenesis, brain monoamines levels, and stress-related hormones) were concomitantly realized after different durations of enriched environment (24 h, 1, 3, or 5 weeks). While short enrichment exposure (24 h) was sufficient to improve object recognition memory performances, a 3-week exposure was required to improve aversive stimulus-based memory performances and to reduce anxiety-like behavior; effects that were not observed with longer duration. The onset of behavioral changes after a 3-week exposure might be supported by higher serotonin levels in the frontal cortex, but seems independent of neurogenesis phenomenon. Additionally, the benefit of 3-week exposure on memory was not observed 3 weeks after cessation of enrichment. Thus, the 3-week exposure appears as an optimal duration in order to induce the most significant behavioral effects and to assess the underlying mechanisms. Altogether, these results suggest that the duration of exposure is a keystone of the beneficial behavioral and neurobiological effects of environmental enrichment. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Low Earth orbit atomic oxygen simulation for durability evaluation of solar reflector surfaces

NASA Technical Reports Server (NTRS)

Degroh, Kim K.; Banks, Bruce A.

1992-01-01

To evaluate the performance and durability of solar reflector surfaces in the atomic oxygen environment typical of low Earth orbit (LEO), one must expose the reflector surface either directly to LEO or to ground-laboratory atomic oxygen environments. Although actual LEO exposures are most desired, such opportunities are typically scarce, expensive, and of limited duration. As a result, ground-laboratory exposures must be relied upon as the most practical long-term durability evaluation technique. Plasma ashers are widely used as LEO simulation facilities by producing atomic oxygen environments for durability evaluation of potential spacecraft materials. Atomic oxygen arrival differs between ground and space exposure in that plasma asher exposure produces isotropic arrival and space solar tracking produces sweeping arrival. Differences in initial impact reaction probability occur, dependent upon the energy and species existing in these environments. Due to the variations in ground-laboratory and space atomic oxygen, quantification of in-space performance based on plasma asher testing is not straightforward. The various atomic oxygen interactions that can occur with reflector surfaces, such as undercutting in organic substrates at protective coating defect sites, ground-laboratory techniques recommended for evaluating the atomic oxygen durability of reflectors based on asher exposures, and computational techniques which make use of ground-laboratory atomic oxygen exposure to predict in-space LEO durability are addressed.

An investigation of the degradation of Fluorinated Ethylene Propylene (FEP) copolymer thermal blanketing materials aboard LDEF in the laboratory

NASA Technical Reports Server (NTRS)

Stiegman, A. E.; Brinza, David E.; Anderson, Mark S.; Minton, Timothy K.; Laue, Eric G.; Liang, Ranty H.

1991-01-01

Samples of fluorinated ethylene propylene copolymer thermal blanketing material, recovered from the Long Duration Exposure Facility (LDEF), were investigated to determine the nature and the extent of degradation due to exposure to the low-Earth-orbit environment. Samples recovered from the ram-facing direction of LDEF, which received vacuum-ultraviolet (VUV) radiation and atomic-oxygen impingement, and samples from the trailing edge, which received almost exclusively VUV exposure, were investigated by scanning electron microscopy and atomic force microscopy. The most significant result of this investigation was found on samples that received only VUV exposure. These samples possessed a hard, embrittled surface layer that was absent from the atomic-oxygen exposed sample and from unexposed control samples. This surface layer is believed to be responsible for the 'synergistic' effect between VUV and atomic oxygen. Overall, the investigation revealed dramatically different morphologies for the two samples. The sample receiving both atomic-oxygen and VUV exposure was deeply eroded and had a characteristic 'rolling' surface morphology, while the sample that received only VUV exposure showed mild erosion and a surface morphology characterized by sharp high-frequency peaks. The morphologies observed in the LDEF samples, including the embrittled surface layer, were successfully duplicated in the laboratory.

Europa Propulsion Valve Seat Material Testing

NASA Technical Reports Server (NTRS)

Addona, Brad M.

2017-01-01

The Europa mission and spacecraft design presented unique challenges for selection of valve seat materials that met the fluid compatibility requirements, and combined fluid compatibility and high radiation exposure level requirements. The Europa spacecraft pressurization system valves will be exposed to fully saturated propellant vapor for the duration of the mission. The effects of Nitrogen Tetroxide (NTO) and Monomethylhydrazine (MMH) propellant vapors on heritage valve seat materials, such as Vespel SP-1 and Polychlorotrifluoroethylene (PCTFE), were evaluated to determine if an alternate material is required. In liquid system applications, Teflon is the only available compatible valve seat material. Radiation exposure data for Teflon in an air or vacuum environment has been previously documented. Radiation exposure data for Teflon in an oxidizer environment such as NTO, was not available, and it was unknown whether the effects would be similar to those on air-exposed samples. Material testing was conducted by Marshall Space Flight Center (MSFC) and White Sands Test Facility (WSTF) to determine the effects of propellant vapor on heritage seat materials for pressurization valve applications, and the effects of combined radiation and NTO propellant exposure on Teflon. The results indicated that changes in heritage pressurization valve seat materials' properties rendered them unsuitable for the Europa application. The combined radiation and NTO exposure testing of Teflon produced results equivalent to combined radiation and air exposure results.

An analysis of historical exposures of pressmen to airborne benzene (1938-2006).

PubMed

Novick, Rachel M; Keenan, James J; Gross, Sherilyn A; Paustenbach, Dennis J

2013-07-01

Benzene is an aromatic hydrocarbon that, with sufficient cumulative lifetime doses, can cause acute myelogenous leukemia. Because of its volatility and solvent properties, it was used in the printing industry in inks, ink solvents, and cleaning agents from the 1930s to the 1970s. This analysis represents the first known attempt to gather and synthesize the available data on historical airborne benzene concentrations in printing facilities and exposures to pressmen. The sources of fugitive benzene vapors from printing operations have been identified as evaporation from ink fountains, exposed sections of the printing cylinder, the paper web, the paper post exit, and spilled ink. In addition, specific activities that could lead to benzene exposure, such as filling the fountains, using solvents to clean the press, and using solvents as personal cleaning agents, potentially occurred multiple times per work period. Eighteen studies were identified that reported workplace airborne concentrations in printing facilities between 1938 and 2006. Typical benzene air concentrations, considering both personal and area samples of various durations, were as high as 200 p.p.m. in the 1930s through the 1950s, 3-35 p.p.m. in the 1960s, 1.3-16 p.p.m. in the 1970s, 0.013-1 in the 1980s, and far less than 1 p.p.m. in the 1990s and 2000s. The decrease in benzene air concentrations by the late 1970s was likely to be linked to the decreased benzene content of printing materials, increased engineering controls, and to more stringent occupational exposure limits.

Dose-response patterns for vibration-induced white finger

PubMed Central

Griffin, M; Bovenzi, M; Nelson, C

2003-01-01

Aims: To investigate alternative relations between cumulative exposures to hand-transmitted vibration (taking account of vibration magnitude, lifetime exposure duration, and frequency of vibration) and the development of white finger (Raynaud's phenomenon). Methods: Three previous studies have been combined to provide a group of 1557 users of powered vibratory tools in seven occupational subgroups: stone grinders, stone carvers, quarry drillers, dockyard caulkers, dockyard boilermakers, dockyard painters, and forest workers. The estimated total operating duration in hours was thus obtained for each subject, for each tool, and for all tools combined. From the vibration magnitudes and exposure durations, seven alternative measurements of cumulative exposure were calculated for each subject, using expressions of the form: dose = ∑amiti, where ai is the acceleration magnitude on tool i, ti is the lifetime exposure duration for tool i, and m = 0, 1, 2, or 4. Results: For all seven alternative dose measures, an increase in dose was associated with a significant increase in the occurrence of vibration-induced white finger, after adjustment for age and smoking. However, dose measures with high powers of acceleration (m > 1) faired less well than measures in which the weighted or unweighted acceleration, and lifetime exposure duration, were given equal weight (m = 1). Dose determined solely by the lifetime exposure duration (without consideration of the vibration magnitude) gave better predictions than measures with m greater than unity. All measures of dose calculated from the unweighted acceleration gave better predictions than the equivalent dose measures using acceleration frequency-weighted according to current standards. Conclusions: Since the total duration of exposure does not discriminate between exposures accumulated over the day and those accumulated over years, a linear relation between vibration magnitude and exposure duration seems appropriate for predicting the occurrence of vibration-induced white finger. Poorer predictions were obtained when the currently recommended frequency weighting was employed than when accelerations at all frequencies were given equal weight. Findings suggest that improvements are possible to both the frequency weighting and the time dependency used to predict the development of vibration-induced white finger in current standards. PMID:12499452

Corneal thermal damage threshold dependence on the exposure duration for near-infrared laser radiation at 1319 nm

NASA Astrophysics Data System (ADS)

Wang, Jiarui; Jiao, Luguang; Chen, Hongxia; Yang, Zaifu; Hu, Xiangjun

2016-01-01

The corneal damage effects induced by 1319-nm transitional near-infrared laser have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. The in vivo corneal damage thresholds (ED50s) were determined in New Zealand rabbits for 1319-nm laser radiation for exposure durations from 75 ms to 10 s. An additional corneal ED50 was determined at 1338 nm for a 5-ms exposure. The incident corneal irradiance diameter was fixed at 2 mm for all exposure conditions to avoid the influence of spot size on threshold. The ED50s given in terms of the corneal radiant exposure for exposure durations of 5 ms, 75 ms, 0.35 s, 2 s, and 10 s were 39.4, 51.5, 87.2, 156.3, and 311.1 J/cm2, respectively. The 39.4 J/cm2 was derived from the ED50 for 1338 nm (27.0 J/cm2). The ED50s for exposure durations of 75 ms to 10 s were correlated by a power law equation, ED50=128.9t0.36 in J/cm2, where t was the input in the unit of second, with correlation coefficient (R) of 0.997. Enough safe margins existed between the ED50s and the maximum permitted exposures from current laser safety standard.

Mortality Among Workers Exposed to Toluene Diisocyanate in the US Polyurethane Foam Industry: Update and Exposure-Response Analyses

PubMed Central

Pinkerton, Lynne E.; Yiin, James H.; Daniels, Robert D.; Fent, Kenneth W.

2017-01-01

Background Mortality among 4,545 toluene diisocyante (TDI)-exposed workers was updated through 2011. The primary outcome of interest was lung cancer. Methods Life table analyses, including internal analyses by exposure duration and cumulative TDI exposure, were conducted. Results Compared with the US population, all cause and all cancer mortality was increased. Lung cancer mortality was increased but was not associated with exposure duration or cumulative TDI exposure. In post hoc analyses, lung cancer mortality was associated with employment duration in finishing jobs, but not in finishing jobs involving cutting polyurethane foam. Conclusions Dermal exposure, in contrast to inhalational exposure, to TDI is expected to be greater in finishing jobs and may play a role in the observed increase in lung cancer mortality. Limitations include the lack of smoking data, uncertainty in the exposure estimates, and exposure estimates that reflected inhalational exposure only. PMID:27346061

LDEF: A bibliography with abstracts

NASA Technical Reports Server (NTRS)

Gouger, H. Garland (Editor)

1992-01-01

The Long Duration Exposure Facility (LDEF) was a free-flying cylindrical structure that housed self-contained experiments in trays mounted on the exterior of the structure. Launched into orbit from the Space Shuttle Challenger in 1984, the LDEF spent almost six years in space before being recovered in 1990. The 57 experiments investigated the effects of the low earth orbit environment on materials, coatings, electronics, thermal systems, seeds, and optics. It also carried experiments that measured crystals growth, cosmic radiation, and micrometeoroids. This bibliography contains 435 selected records from the NASA aerospace database covering the years 1973 through June of 1992. The citations are arranged within subject categories by author and date of publication.

Morphology of meteoroid and space debris craters on LDEF metal targets

NASA Technical Reports Server (NTRS)

Love, S. G.; Brownlee, D. E.; King, N. L.; Hoerz, F.

1994-01-01

We measured the depths, average diameters, and circularity indices of over 600 micrometeoroid and space debris craters on various metal surfaces exposed to space on the Long Duration Exposure Facility (LDEF) satellite, as a test of some of the formalisms used to convert the diameters of craters on space-exposed surfaces into penetration depths for the purpose of calculating impactor sizes or masses. The topics covered include the following: targe materials orientation; crater measurements and sample populations; effects of oblique impacts; effects of projectile velocity; effects of crater size; effects of target hardness; effects of target density; and effects of projectile properties.

Final results of the Space Exposed Experiment Developed for Students (SEEDS) P-0004-2

NASA Technical Reports Server (NTRS)

Grigsby, Doris K.

1992-01-01

Space Exposed Experiment Developed for Students (SEEDS), resulted in the distribution of over 132,000 SEED kits in 1990. The kits contained Rutger's tomato seeds that had flown on the Long Duration Exposure Facility (LDEF) as well as seeds that had been stored in a climate controlled warehouse for the same period of time. Students compared germination and growth rate characteristics of the two seeds groups and returned data to NASA for analysis. The scientific information gained was valuable as students shared the excitement of taking part in a national project. Of greater importance was the subsequent interest generated in science education.

A photon phreak digs the LDEF happening

NASA Technical Reports Server (NTRS)

Smith, Alan R.; Hurley, Donna L.

1993-01-01

A year ago at the First Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium, detailed measurements on trunnion sections, as well as results from 'intentional' samples (Co, Ni, In, Ta, and V) and spacecraft parts were reported. For this year's Symposium, some of these findings are re-evaluated in combination with more recent results, to cast a longer perspective on the LDEF experience, and to sketch some promising avenues toward more effective participation in future missions. The LDEF analysis effort has been a superb training exercise, from which lessons learned need to be applied to future missions - right back to the early phases of mission planning.

Identification and evaluation of lubricants, adhesives, and seals used on LDEF

NASA Technical Reports Server (NTRS)

Keough, Bruce

1992-01-01

A variety of lubricants, adhesives, and seals were flown on Long Duration Exposure Facility (LDEF). They were used in the fabrication and assembly of the experiments similar to other spacecraft applications. Typically, these materials were not exposed to U.V. radiation or atomic oxygen, except possibly around the perimeter of the joints. Most of these materials were of secondary interest and were only investigated by visual examination and a 'Did they fall?' criteria. Because of this role, most applications had only a few specimens, not enough for statistical data generation. Often, no control samples were kept, and documentation of what was used was occasionally sketchy.

Preliminary flight test results from the advanced photovoltaic experiment

NASA Technical Reports Server (NTRS)

Brinker, David J.; Hickey, John R.

1990-01-01

The Advanced Photovoltaic Experiment is a space flight test designed to provide reference cell standards for photovoltaic measurement as well as to investigate the solar spectrum and the effect of the space environment on solar cells. After a flight of 69 months in low earth orbit as part of the Long Duration Exposure Facility set of experiments, it was retrieved in January, 1990. The electronic data acquisition system functioned as designed, measuring and recording cell performance data over the first 358 days of flight, limited by battery lifetime. Significant physical changes are also readily apparent, including erosion of front surface paint, micrometeoroid and debris catering and contamination.

Preliminary results from the advanced photovoltaic experiment flight test

NASA Technical Reports Server (NTRS)

Brinker, David J.; Hart, Russell E., Jr.; Hickey, John R.

1990-01-01

The Advanced Photovoltaic Experiment is a space flight test designed to provide reference cell standards for photovoltaic measurement as well as to investigate the solar spectrum and the effect of the space environment on solar cells. After a flight of 69 months in low earth orbit as part of the Long Duration Exposure Facility set of experiments, it was retrieved in January, 1990. The electronic data acquisition system functioned as designed, measuring and recording cell performance data over the first 358 days of flight; limited by battery lifetime. Significant physical changes are also readily apparent, including erosion of front surface paint, micrometeoroid and debris catering and contamination.

Transmittance measurements of ultra violet and visible wavelength interference filters flown aboard LDEF

NASA Technical Reports Server (NTRS)

Mooney, Thomas A.; Smajkiewicz, Ali

1991-01-01

A set of ten interference filters for the UV and VIS spectral region were flown on the surface of the Long Duration Exposure Facility (LDEF) Tray B-8 along with earth radiation budget (ERB) components from the Eppley Laboratory. Transmittance changes and other degradation observed after the return of the filters to Barr are reported. Substrates, coatings, and (where applicable) cement materials are identified. In general, all filters except those containing lead compounds survived well. Metal dielectric filters for the UV developed large numbers of pinholes which caused an increase in transmittance. Band shapes and spectral positioning, however, did not change.

Surface characterization of selected LDEF tray clamps

NASA Technical Reports Server (NTRS)

Cromer, T. F.; Grammer, H. L.; Wightman, J. P.; Young, Philip R.; Slemp, Wayne S.

1993-01-01

The surface characterization of chromic acid anodized 6061-T6 aluminum alloy tray clamps has shown differences in surface chemistry depending upon the position on the Long Duration Exposure Facility (LDEF). Water contact angle results showed no changes in wettability of the tray clamps. The overall surface topography of the control, trailing edge(E3) and leading edge(D9) samples was similar. The thickness of the aluminum oxide layer for all samples determined by Auger depth profiling was less than one micron. X-ray photoelectron spectroscopy (XPS) analysis of the tray clamps showed significant differences in the surface composition. Carbon and silicon containing compounds were the primary contaminants detected.

Heat pipes in space and on earth

NASA Technical Reports Server (NTRS)

Ollendorf, S.

1978-01-01

The performance of heat pipes used in the thermal control system of spacecraft such as OAO-III and ATS-6 is discussed, and applications of heat pipes to permafrost stabilization on the Alaska Pipeline and to heat recovery systems are described. Particular attention is given to the ATS-6, launched in 1974, which employs 55 heat pipes to carry solar and internal power loads to radiator surfaces. In addition, experiments involving radiative cooling based on cryogenic heat pipes have been planned for the Long Duration Exposure Facility spacecraft and for Spacelab. The role of heat pipes in Space Shuttle heat rejection services is also mentioned.

Mechanical properties of silicate glasses exposed to a low-Earth orbit

NASA Technical Reports Server (NTRS)

Wiedlocher, David E.; Tucker, Dennis S.; Nichols, Ron; Kinser, Donald L.

1992-01-01

The effects of a 5.8 year exposure to low earth orbit environment upon the mechanical properties of commercial optical fused silica, low iron soda-lime-silica, Pyrex 7740, Vycor 7913, BK-7, and the glass ceramic Zerodur were examined. Mechanical testing employed the ASTM-F-394 piston on 3-ball method in a liquid nitrogen environment. Samples were exposed on the Long Duration Exposure Facility (LDEF) in two locations. Impacts were observed on all specimens except Vycor. Weibull analysis as well as a standard statistical evaluation were conducted. The Weibull analysis revealed no differences between control samples and the two exposed samples. We thus concluded that radiation components of the Earth orbital environment did not degrade the mechanical strength of the samples examined within the limits of experimental error. The upper bound of strength degradation for meteorite impacted samples based upon statistical analysis and observation was 50 percent.

LDEF materials special investigation group's data bases

NASA Technical Reports Server (NTRS)

Strickland, John W.; Funk, Joan G.; Davis, John M.

1993-01-01

The Long Duration Exposure Facility (LDEF) was composed of and contained a wide array of materials, representing the largest collection of materials flown for space exposure and returned for ground-based analyses to date. The results and implications of the data from these materials are the foundation on which future space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been tasked with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the space user community in an easily accessed, user-friendly form. The format and content of the data bases developed or being developed to accomplish this task are discussed. The hardware and software requirements for each of the three data bases are discussed along with current availability of the data bases.

Materials And Processes Technical Information System (MAPTIS) LDEF materials data base

NASA Technical Reports Server (NTRS)

Funk, Joan G.; Strickland, John W.; Davis, John M.

1993-01-01

A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated from LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux) and author(s) or principal investigator(s). Tne LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which has been computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. The LDEF Materials Data Base is described and step-by-step example searches using the data base are included. Information on how to become an authorized user of the system is included.

Laser-induced fluorescence of space-exposed polyurethane

NASA Technical Reports Server (NTRS)

Hill, Ralph H., Jr.

1993-01-01

The object of this work was to utilize laser-induced fluorescence technique to characterize several samples of space-exposed polyurethane. These samples were flown on the Long Duration Exposure Facility (LDEF), which was in a shuttle-like orbit for nearly 6 years. Because of our present work to develop laser-induced-fluorescence inspection techniques for polymers, space-exposed samples and controls were lent to us for evaluation. These samples had been attached to the outer surface of LDEF; therefore, they were subjected to thermal cycling, solar ultraviolet radiation, vacuum, and atomic oxygen. It is well documented that atomic oxygen and ultraviolet exposure have detrimental effects on many polymers. This was a unique opportunity to make measurements on material that had been naturally degraded by an unusual environment. During our past work, data have come from artificially degraded samples and generally have demonstrated a correlation between laser-induced fluorescence and tensile strength or elasticity.

In Data We Trust? Comparison of Electronic Versus Manual Abstraction of Antimicrobial Prescribing Quality Metrics for Hospitalized Veterans With Pneumonia.

PubMed

Jones, Barbara E; Haroldsen, Candace; Madaras-Kelly, Karl; Goetz, Matthew B; Ying, Jian; Sauer, Brian; Jones, Makoto M; Leecaster, Molly; Greene, Tom; Fridkin, Scott K; Neuhauser, Melinda M; Samore, Matthew H

2018-07-01

Electronic health records provide the opportunity to assess system-wide quality measures. Veterans Affairs Pharmacy Benefits Management Center for Medication Safety uses medication use evaluation (MUE) through manual review of the electronic health records. To compare an electronic MUE approach versus human/manual review for extraction of antibiotic use (choice and duration) and severity metrics. Retrospective. Hospitalizations for uncomplicated pneumonia occurring during 2013 at 30 Veterans Affairs facilities. We compared summary statistics, individual hospitalization-level agreement, facility-level consistency, and patterns of variation between electronic and manual MUE for initial severity, antibiotic choice, daily clinical stability, and antibiotic duration. Among 2004 hospitalizations, electronic and manual abstraction methods showed high individual hospitalization-level agreement for initial severity measures (agreement=86%-98%, κ=0.5-0.82), antibiotic choice (agreement=89%-100%, κ=0.70-0.94), and facility-level consistency for empiric antibiotic choice (anti-MRSA r=0.97, P<0.001; antipseudomonal r=0.95, P<0.001) and therapy duration (r=0.77, P<0.001) but lower facility-level consistency for days to clinical stability (r=0.52, P=0.006) or excessive duration of therapy (r=0.55, P=0.005). Both methods identified widespread facility-level variation in antibiotic choice, but we found additional variation in manual estimation of excessive antibiotic duration and initial illness severity. Electronic and manual MUE agreed well for illness severity, antibiotic choice, and duration of therapy in pneumonia at both the individual and facility levels. Manual MUE showed additional reviewer-level variation in estimation of initial illness severity and excessive antibiotic use. Electronic MUE allows for reliable, scalable tracking of national patterns of antimicrobial use, enabling the examination of system-wide interventions to improve quality.

Why, when and how should exposure be considered at the within-host scale? A modelling contribution to PRRSv infection.

PubMed

Go, Natacha; Belloc, Catherine; Bidot, Caroline; Touzeau, Suzanne

2018-05-21

Understanding the impact of pathogen exposure on the within-host dynamics and its outcome in terms of infectiousness is a key issue to better understand and control the infection spread. Most experimental and modelling studies tackling this issue looked at the impact of the exposure dose on the infection probability and pathogen load, very few on the within-host immune response. Our aim was to explore the impact on the within-host response not only of the exposure dose, but also of its duration and peak, for contrasted virulence levels. We used an integrative modelling approach of the within-host dynamics at the between-cell level. We focused on the porcine reproductive and respiratory syndrome virus, a major concern for the swine industry. We quantified the impact of exposure and virulence on the viral dynamics and immune response by global sensitivity analyses and descriptive statistics. We found that the area under the viral curve, an indicator of the infection severity, was fully determined by the exposure intensity. The infection duration increased with the strain virulence and, for a given strain, exhibited a positive linear correlation with the exposure intensity logarithm and the exposure duration. Taking into account the exposure intensity is hence necessary. Besides, representing the exposure due to contacts by a single punctual dose would tend to underestimate the infection duration. As the infection severity and duration both contribute to the pig infectiousness, a prolonged exposure of the adequate intensity would be recommended in an immuno-epidemiological context.

Chronic Respiratory Symptoms and Lung Function in Agricultural Workers - Influence of Exposure Duration and Smoking.

PubMed

Stoleski, Saso; Minov, Jordan; Mijakoski, Dragan; Karadzinska-Bislimovska, Jovanka

2015-03-15

Job exposure in agricultural workers often leads to respiratory impairment. To assess the influence of exposure duration and smoking on chronic respiratory symptoms and ventilatory capacity in agricultural workers. A cross-sectional study covered 75 agricultural workers, compared with an equal number of office workers matched by age, exposure duration and smoking status. Standardized questionnaire was used to obtain data on chronic respiratory symptoms, job and smoking history. Lung functional testing was performed by spirometry. The prevalence of respiratory symptoms was higher in agricultural workers, with significant difference for cough (P = 0.034), and dyspnea (P = 0.028). Chronic respiratory symptoms among agricultural workers were significantly associated with duration of exposure (P < 0.05) and daily smoking (P < 0.01), as well as with daily smoking in controls (P < 0.01). The average values of spirometric parameters in exposed workers were significantly different for MEF50 (P = 0.002), MEF75 (P = 0.000), and MEF25-75 (P = 0.049). Obstructive changes in small airways in exposed workers were strongly related to exposure duration (P < 0.05) and smoking (P < 0.01). Agricultural workers with job exposure more than 15 years had more expressed adverse respiratory symptoms and lung function decline. The results confirmed the influence of agricultural exposure and daily smoking on chronic respiratory symptoms and airflow limitation, primarily targeting the small airways.

Methods for evaluating temporal trends in noise exposure

PubMed Central

Neitzel, RL; Galusha, D; Dixon-Ernst, C; Rabinowitz, PM

2014-01-01

Objective Hearing conservation programs have been mandatory in many US industries since 1983. Since then, three program elements (audiometric testing, hearing protection, and training) have been the focus of much research. By comparison, little has been done on noise exposure evaluation. Design and study sample Utilizing a large dataset (>10,000 measurements over 20 years) from eight facilities operated by a multinational aluminum manufacturing company, we evaluated several approaches to assessing temporal trends in Time Weighted Average (TWA) exposures and the fraction of measurements exceeding 85 dBA by facility, by exposure group within facility, and by individual worker within facility. Results Overall, exposures declined across locations over the study period. Several facilities demonstrated substantial reductions in exposure, and the results of mean noise levels and exceedance fractions generally showed good agreement. The results of analyses at the individual level diverged with analyses by facility and exposure group within facility, suggesting that individual-level analyses, while challenging, may provide important information not available from coarser levels of analysis. Conclusions Validated metrics are needed to allow for assessment of temporal trends in noise exposure. Such metrics will improve our ability to characterize, in a standardized manner, efforts to reduce noise-induced hearing loss. PMID:24564696

Methods for evaluating temporal trends in noise exposure.

PubMed

Neitzel, R L; Galusha, D; Dixon-Ernst, C; Rabinowitz, P M

2014-03-01

Hearing conservation programs have been mandatory in many US industries since 1983. Since then, three program elements (audiometric testing, hearing protection, and training) have been the focus of much research. By comparison, little has been done on noise exposure evaluation. Temporal trends in time weighted average (TWA) exposures and the fraction of measurements exceeding 85 dBA were evaluated by facility, by exposure group within facility, and by individual worker within facility. A large dataset (> 10 000 measurements over 20 years) from eight facilities operated by a multinational aluminum manufacturing company was studied. Overall, exposures declined across locations over the study period. Several facilities demonstrated substantial reductions in exposure, and the results of mean noise levels and exceedance fractions generally showed good agreement. The results of analyses at the individual level diverged with analyses by facility and exposure group within facility, suggesting that individual-level analyses, while challenging, may provide important information not available from coarser levels of analysis. Validated metrics are needed to allow for assessment of temporal trends in noise exposure. Such metrics will improve our ability to characterize, in a standardized manner, efforts to reduce noise-induced hearing loss.

Hearing in Laboratory Animals: Strain Differences and Nonauditory Effects of Noise

PubMed Central

Parrish, Jennifer L.; Hughes, Larry F.; Toth, Linda A.; Caspary, Donald M.

2013-01-01

Hearing in laboratory animals is a topic that traditionally has been the domain of the auditory researcher. However, hearing loss and exposure to various environmental sounds can lead to changes in multiple organ systems, making what laboratory animals hear of consequence for researchers beyond those solely interested in hearing. For example, several inbred mouse strains commonly used in biomedical research (e.g., C57BL/6, DBA/2, and BALB/c) experience a genetically determined, progressive hearing loss that can lead to secondary changes in systems ranging from brain neurochemistry to social behavior. Both researchers and laboratory animal facility personnel should be aware of both strain and species differences in hearing in order to minimize potentially confounding variables in their research and to aid in the interpretation of data. Independent of genetic differences, acoustic noise levels in laboratory animal facilities can have considerable effects on the inhabitants. A large body of literature describes the nonauditory impact of noise on the biology and behavior of various strains and species of laboratory animals. The broad systemic effects of noise exposure include changes in endocrine and cardiovascular function, sleep–wake cycle disturbances, seizure susceptibility, and an array of behavioral changes. These changes are determined partly by species and strain; partly by noise intensity level, duration, predictability, and other characteristics of the sound; and partly by animal history and exposure context. This article reviews some of the basic strain and species differences in hearing and outlines how the acoustic environment affects different mammals. PMID:15766204

Screening for beryllium disease among construction trade workers at Department of Energy nuclear sites.

PubMed

Welch, Laura; Ringen, Knut; Bingham, Eula; Dement, John; Takaro, Tim; McGowan, William; Chen, Anna; Quinn, Patricia

2004-09-01

To determine whether current and former construction workers are at significant risk for occupational illnesses from work at the Department of Energy's (DOE) nuclear weapons facilities, screening programs were undertaken at the Hanford Nuclear Reservation, Oak Ridge Reservation, and the Savannah River Site. Medical examination for beryllium disease used a medical history and a beryllium blood lymphocyte proliferation test (BeLPT). Stratified and multivariate logistic regression analyses were used to explore the risk of disease by age, race, sex, trade, duration of DOE employment, reported work in buildings where beryllium was used, and time since last DOE site employment. Of the 3,842 workers included in this study, 34% reported exposure to beryllium. Overall, 2.2% of workers had at least one abnormal BeLPT test, and 1.4% were also abnormal on a second test. Regression analyses demonstrated increased risk of having at least one abnormal BeLPT to be associated with ever working in a site building where beryllium activities had taken place. The prevalence of beryllium sensitivity and chronic beryllium disease (CBD) in construction workers is described and the positive predictive value of the BeLPT in a population with less intense exposure to beryllium than other populations that have been screened is discussed. The BeLPT findings and finding of cases of CBD demonstrate that some of these workers had significant exposure, most likely, during maintenance, repair, renovation, or demolition in facilities where beryllium was used.

Frequency-risk and duration-risk relations between second-hand smoke exposure and menopausal symptoms among middle-aged women in Guangzhou, China.

PubMed

Ye, X; Yao, Z; Xu, Y; Zhou, S; Gao, Y; Chen, S; Yang, Y

2015-04-01

Tobacco smoking and menopausal symptoms are strongly associated, but the possible effects of second-hand smoke (SHS) have not been evaluated. This study aimed to explore the possible frequency-risk and duration-risk relations between SHS exposure and menopausal symptoms among non-smoking, middle-aged women. A cross-sectional survey was conducted in Guangzhou, China using a stratified three-stage sampling method. Menopausal symptoms were measured by the modified Kupperman Index with a cut-off point of 7. The frequency-risk and duration-risk relations between SHS exposure and menopausal symptoms were examined using logistic regression models. Compared with non-exposure, SHS exposure was associated with increased menopausal symptoms (odds ratio (OR) = 1.69, 95% confidence interval (CI) 1.22-2.33 for exposure in any of the venues). The trend analysis showed that there were frequency-risk (OR = 1.43 for occasional exposure; OR = 2.30 for regular exposure; p for linear trend < 0.001) and duration-risk (OR = 1.09 for 1-15 years; OR = 1.99 for > 15 years; p for linear trend < 0.001) relations. When examining the frequency-risk and duration-risk relations by source of exposure (in homes or in workplaces), there was still evidence of increasing trend for risk of menopausal symptoms. Findings from the present study suggest that SHS exposure is positively associated with menopausal symptoms in middle-aged women in a dose-response manner and highlight the need for further research to establish the mechanisms of the association.

Comparison of Biological Responses in Rats Under Various Cigarette Smoke Exposure Conditions

PubMed Central

Tsuji, Hiroyuki; Fujimoto, Hitoshi; Matsuura, Daiki; Nishino, Tomoki; Lee, K Monica; Yoshimura, Hiroyuki

2013-01-01

A variety of exposure regimens of cigarette smoke have been used in animal models of lung diseases. In this study, we compared biological responses of smoke exposure in rats, using different smoke concentrations (wet total particulate matter [WTPM]), daily exposure durations, and total days of exposure. As a range-finding acute study, we first compared pulmonary responses between SD and F344 strains after a single nose-only exposure to mainstream cigarette smoke or LPS. Secondly, F344 rats were exposed to cigarette smoke for 2 or 13 weeks under the comparable daily exposure dose (WTPM concentration x daily exposure duration; according to Haber’s rule) but at a different WTPM concentration or daily exposure duration. Blood carboxylhemoglobin was increased linearly to the WTPM concentration, while urinary nicotine plus cotinine value was higher for the longer daily exposure than the corresponding shorter exposure groups. Gamma glutamyl transferase activity in bronchoalveolar lavage fluid (BALF) was increased dose dependently after 2 and 13 weeks of cigarette smoke exposure, while the neutrophil content in BALF was not increased notably. Smoke-exposed groups showed reduced body weight gain and increased relative lung and heart weights. While BALF parameters and the relative lung weights suggest pulmonary responses, histopathological examination showed epithelial lesions mainly in the upper respiratory organs (nose and larynx). Collectively, the results indicate that, under the employed study design, the equivalent daily exposure dose (exposure concentration x duration) induces equivalent pulmonary responses in rats. PMID:23914058

First biological and dosimetric results of the free flyer biostack experiment AO015 on LDEF

NASA Technical Reports Server (NTRS)

Reitz, G.; Buecker, H.; Facius, R.; Horneck, G.; Schaeffer, M.; Schott, J. U.; Bayonove, J.; Beaujean, R.; Benton, E. V.; Delpoux, M.

1991-01-01

The main objectives of the Biostack Experiment are to study the effectiveness of the structured components of the cosmic radiation to bacterial spores, plant seeds, and animal cysts for a long duration spaceflight and to get dosimetric data such as particle fluences and spectra and total doses for the Long Duration Exposure Facility orbit. The configuration of the experiment packages allows the localization of the trajectory of the particles in each biological layer and to correlate the potential biological impairment or injury with the physical characteristics of the responsible particle. Although the Biostack Experiment was designed for a long duration flight of only nine months, most of the biological systems show a high hatching or germination rate. Some of the first observations are an increase of the mutation rate of embryonic lethals in the second generation of Arabidopsis seeds, somatic mutations, and a reduction of growth rates of corn plants and a reduction of life span of Artemia salina shrimps. The different passive detector systems are also in a good shape and give access to a proper dosimetric analysis. The results are summarized, and some aspects of future analysis are shown.

OZONE-INDUCED RESPIRATORY SYMPTOMS AND LUNG FUNCTION DECREMENTS IN HUMANS: EXPOSURE-RESPONSE MODELS

EPA Science Inventory

Short duration exposure to ozone (<8 hr) is known to result in lung function decrements and respiratory symptoms in humans. The magnitudes of these responses are functions of ozone concentration (C), activity level measured by minute ventilation (Ve), duration of exposure (T), a...

Long-Duration Orbit Exposure Experiment with Sub-Surface Microorganism from a Mars Terrestrial Analog

NASA Astrophysics Data System (ADS)

Davila, A. F.; Lim, D.; Fairen, A. G.; Uceda, E. R.; Zavaleta, J.; McKay, C.

2007-07-01

Orbit Exposure Experiments (OEE) allow us to test the possibility of life transfer between planets and moons. Deep sub-surface microorganisms may be the best candidates to survive long-term exposure to space conditions. A long duration OEE is proposed to test our hypothesis.

Acute respiratory symptoms and evacuation-related behavior after exposure to chlorine gas leakage.

PubMed

Han, Sung-Woo; Choi, Won-Jun; Yi, Min-Kee; Song, Seng-Ho; Lee, Dong-Hoon; Han, Sang-Hwan

2016-01-01

A study was performed on the accidental chlorine gas leakage that occurred in a factory of printed circuit boards manufactured without chlorine. Health examination was performed for all 52 workers suspected of exposure to chlorine gas, and their evacuation-related behaviors were observed in addition to analyzing the factors that affected the duration of their acute respiratory symptoms. Behavioral characteristics during the incidence of the accidental chlorine gas leakage, the estimated time of exposure, and the duration of subjective acute respiratory symptoms were investigated. In addition, clinical examination, chest radiography, and dental erosion test were performed. As variables that affected the duration of respiratory symptoms, dose group, body weight, age, sex, smoking, work period, and wearing a protective gear were included and analyzed by using the Cox proportional hazard model. Of 47 workers exposed to chlorine gas, 36 (77 %) developed more than one subjective symptom. The duration of the subjective symptoms according to exposure level significantly differed, with a median of 1 day (range, 0-5 days) in the low-exposure group and 2 days (range, 0-25 days) in the high-exposure group. Among the variables that affected the duration of the acute respiratory symptoms, which were analyzed by using the Cox proportional hazard model, only exposure level was significant (hazard ratio 2.087, 95 % CI = 1.119, 3.890). Regarding the evacuation-related behaviors, 22 workers (47 %) voluntarily evacuated to a safety zone immediately after recognizing the accidental exposure, but 25 workers (43 %) delayed evacuation until the start of mandatory evacuation (min 5, max 25 min). The duration of the subjective acute respiratory symptoms significantly differed between the low- and high-exposure groups. Among the 27 workers in the high-exposure group, 17 misjudged the toxicity after being aware of the gas leakage, which is a relatively high number.

Effects of the LDEF orbital environment on the reflectance of optical mirror materials

NASA Technical Reports Server (NTRS)

Herzig, Howard; Fleetwood, Charles, Jr.

1995-01-01

Specimens of eight different optical mirror materials were flown in low earth orbit as part of the Long Duration Exposure Facility (LDEF) manifest to determine their ability to withstand exposure to the residual atomic oxygen and other environmental effects at those altitudes. Optical thin films of aluminum, gold, iridium, osmium, platinum, magnesium fluoride-overcoated aluminum and reactively deposited, silicon monoxide-protected aluminum, all of which were vacuum deposited on polished fused silica substrates, were included as part of Experiment S0010, Exposure of Spacecraft Coatings. Two specimens of polished, chemical vapor deposited (CVD) silicon carbide were installed in sites available in Experiment A0114, Interaction of Atomic Oxygen with Solid Surfaces at Orbital Altitudes, which included trays in two of the spacecraft bays, one on the leading edge and the other on the trailing edge. One of the silicon carbide samples was located in each of these trays. This paper will compare specular reflectance data from the preflight and postflight measurements made on each of these samples and attempt to explain the changes in light of the specific environments to which the experiments were exposed.

Surface analyses of composites exposed to the space environment on LDEF

NASA Technical Reports Server (NTRS)

Mallon, Joseph J.; Uht, Joseph C.; Hemminger, Carol S.

1993-01-01

A series of surface analyses on carbon fiber/poly(arylacetylene) (PAA) matrix composites that were exposed to the space environment on the Long Duration Exposure Facility (LDEF) satellite were conducted. These composite panels were arranged in pairs on both the leading edge and trailing edge of LDEF. None of the composites were catastrophically damaged by nearly six years of exposure to the space environment. Composites on the leading edge exhibited from 25 to 125 microns of surface erosion, but trailing edge panels exhibited no physical appearance changes due to exposure. Scanning electron microscopy (SEM) was used to show that the erosion morphology on the leading edge samples was dominated by crevasses parallel to the fibers with triangular cross sections 10 to 100 microns in depth. The edges of the crevasses were well defined and penetrated through both matrix and fiber. The data suggest that the carbon fibers are playing an important role in crevasse initiation and/or enlargement, and in the overall erosion rate of the composite. X-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectroscopy (EDS) results showed contamination from in-flight sources of silicone.

Organic matrix composite protective coatings for space applications

NASA Technical Reports Server (NTRS)

Dursch, Harry W.; George, Pete

1995-01-01

Successful use of composites in low earth orbit (LEO) depends on their ability to survive long-term exposure to atomic oxygen (AO), ultraviolet radiation, charged particle radiation, thermal cycling, and micrometeoroid and space debris. The AO environment is especially severe for unprotected organic matrix composites surfaces in LEO. Ram facing unprotected graphite/epoxy flown on the 69-month Long Duration Exposure Facility (LDEF) mission lost up to one ply of thickness (5 mils) resulting in decreased mechanical properties. The expected AO fluence of the 30 year Space Station Alpha mission is approximately 20 times that seen on LDEF. This exposure would result in significant material loss of unprotected ram facing organic matrix composites. Several protective coatings for composites were flown on LDEF including anodized aluminum, vacuum deposited coatings, a variety of thermal control coatings, metalized Teflon, and leafing aluminum. Results from the testing and analysis of the coated and uncoated composite specimens flown on LDEF's leading and trailing edges provide the baseline for determining the effectiveness of protectively coated composites in LEO. In addition to LDEF results, results from shuttle flight experiments and ground based testing will be discussed.

Ellipsometric study of oxide films formed on LDEF metal samples

NASA Technical Reports Server (NTRS)

Franzen, W.; Brodkin, J. S.; Sengupta, L. C.; Sagalyn, P. L.

1992-01-01

The optical constants of samples of six different metals (Al, Cu, Ni, Ta, W, and Zr) exposed to space on the Long Duration Exposure Facility (LDEF) were studied by variable angle spectroscopic ellipsometry. Measurements were also carried out on portions of each sample which were shielded from direct exposure by a metal bar. A least-squares fit of the data using an effective medium approximation was then carried out, with thickness and composition of surface films formed on the metal substrates as variable parameters. The analysis revealed that exposed portions of the Cu, Ni, Ta, and Zr samples are covered with porous oxide films ranging in thickness from 500 to 1000 A. The 410 A thick film of Al2O3 on the exposed Al sample is practically free of voids. Except for Cu, the shielded portions of these metals are covered by thin non-porous oxide films characteristic of exposure to air. The shielded part of the Cu sample has a much thicker porous coating of Cu2O. The tungsten data could not be analyzed.

The 37-day flight of CREAM during the 2009-2010 austral summer

NASA Astrophysics Data System (ADS)

Seo, Eun-Suk

The balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment was launched from McMurdo Station Antarctica on December 1, 2009, an early-launch record for Antarctic Long Duration Balloon (LDB) flights. A cumulative exposure of ˜ 156 days was achieved when this 37-day fifth flight of CREAM was terminated over the Ross Ice Shelf on January 8, 2010. Combining a sampling calorimeter for energy measurement with multiple charge detectors for particle identification, CREAM-V provided a large data sample to measure elemental spectra for 1 ≤ Z ≤ 26 in energies above 1014 eV. This was the first time that CREAM was supported with the standard Support Instrumentation Package (SIP) for LDB payloads. The first four flights were supported by the Command and Data Module (CDM) developed by the NASA Wallops Flight Facility for Ultra Long Duration Balloon (ULDB) flights. The instrument performance, results from the ongoing data analysis, and future plans will be presented.

Orbital debris and meteoroids: Results from retrieved spacecraft surfaces

NASA Astrophysics Data System (ADS)

Mandeville, J. C.

1993-08-01

Near-Earth space contains natural and man-made particles, whose size distribution ranges from submicron sized particles to cm sized objects. This environment causes a grave threat to space missions, mainly for future manned or long duration missions. Several experiments devoted to the study of this environment have been recently retrieved from space. Among them several were located on the NASA Long Duration Exposure Facility (LDEF) and on the Russian MIR Space Station. Evaluation of hypervelocity impact features gives valuable information on size distribution of small dust particles present in low Earth orbit. Chemical identification of projectile remnants is possible in many instances, thus allowing a discrimination between extraterrestrial particles and man-made orbital debris. A preliminary comparison of flight data with current modeling of meteoroids and space debris shows a fair agreement. However impact of particles identified as space debris on the trailing side of LDEF, not predicted by the models, could be the result of space debris in highly excentric orbits, probably associated with GTO objects.

Temporal integration property of stereopsis after higher-order aberration correction

PubMed Central

Kang, Jian; Dai, Yun; Zhang, Yudong

2015-01-01

Based on a binocular adaptive optics visual simulator, we investigated the effect of higher-order aberration correction on the temporal integration property of stereopsis. Stereo threshold for line stimuli, viewed in 550nm monochromatic light, was measured as a function of exposure duration, with higher-order aberrations uncorrected, binocularly corrected or monocularly corrected. Under all optical conditions, stereo threshold decreased with increasing exposure duration until a steady-state threshold was reached. The critical duration was determined by a quadratic summation model and the high goodness of fit suggested this model was reasonable. For normal subjects, the slope for stereo threshold versus exposure duration was about −0.5 on logarithmic coordinates, and the critical duration was about 200 ms. Both the slope and the critical duration were independent of the optical condition of the eye, showing no significant effect of higher-order aberration correction on the temporal integration property of stereopsis. PMID:26601010

Diagnostic delay amongst tuberculosis patients in Jogjakarta Province, Indonesia is related to the quality of services in DOTS facilities.

PubMed

Ahmad, Riris Andono; Mahendradhata, Yodi; Utarini, Adi; de Vlas, Sake J

2011-04-01

To understand determinants of care-seeking patterns and diagnostic delay amongst tuberculosis (TB) patients diagnosed at direct observed treatment short course (DOTS) facilities in Jogjakarta, Indonesia. Cross-sectional survey amongst newly diagnosed TB patients in 89 DOTS facilities whose history of care-seeking was reconstructed through retrospective interviews gathering data on socio-demographic determinants, onset of TB symptoms, type of health facilities visited, duration of each care-seeking action were recorded. Two hundred and fifty-three TB patients were included in the study whose median duration of patients' delay was 1 week and whose total duration of diagnostic delay was 5.4 weeks. The median number of visits was 4. Many of the patients' socio-demographic determinants were not associated with the care-seeking patterns, and no socio-demographic determinants were associated with the duration of diagnostic delay. More than 60% of TB patients started their care-seeking processes outside DOTS facilities, but the number of visits in DOTS facilities was greater during the overall care-seeking process. Surprisingly, patient's immediate visits to a DOTS facility did not correspond to shorter diagnostic delay. Diagnostic delay in Jogjakarta province was not associated with patients' socio demographic factors, but rather with the health system providing DOTS services. This suggests that strengthening the health system and improving diagnostic quality within DOTS services is now a more rational strategy than expanding the TB programme to engage more providers. © 2010 Blackwell Publishing Ltd.

Sanitation and Hygiene-Specific Risk Factors for Moderate-to-Severe Diarrhea in Young Children in the Global Enteric Multicenter Study, 2007-2011: Case-Control Study.

PubMed

Baker, Kelly K; O'Reilly, Ciara E; Levine, Myron M; Kotloff, Karen L; Nataro, James P; Ayers, Tracy L; Farag, Tamer H; Nasrin, Dilruba; Blackwelder, William C; Wu, Yukun; Alonso, Pedro L; Breiman, Robert F; Omore, Richard; Faruque, Abu S G; Das, Sumon Kumar; Ahmed, Shahnawaz; Saha, Debasish; Sow, Samba O; Sur, Dipika; Zaidi, Anita K M; Quadri, Fahreen; Mintz, Eric D

2016-05-01

Diarrheal disease is the second leading cause of disease in children less than 5 y of age. Poor water, sanitation, and hygiene conditions are the primary routes of exposure and infection. Sanitation and hygiene interventions are estimated to generate a 36% and 48% reduction in diarrheal risk in young children, respectively. Little is known about whether the number of households sharing a sanitation facility affects a child's risk of diarrhea. The objective of this study was to describe sanitation and hygiene access across the Global Enteric Multicenter Study (GEMS) sites in Africa and South Asia and to assess sanitation and hygiene exposures, including shared sanitation access, as risk factors for moderate-to-severe diarrhea (MSD) in children less than 5 y of age. The GEMS matched case-control study was conducted between December 1, 2007, and March 3, 2011, at seven sites in Basse, The Gambia; Nyanza Province, Kenya; Bamako, Mali; Manhiça, Mozambique; Mirzapur, Bangladesh; Kolkata, India; and Karachi, Pakistan. Data was collected for 8,592 case children aged <5 y old experiencing MSD and for 12,390 asymptomatic age, gender, and neighborhood-matched controls. An MSD case was defined as a child with a diarrheal illness <7 d duration comprising ≥3 loose stools in 24 h and ≥1 of the following: sunken eyes, skin tenting, dysentery, intravenous (IV) rehydration, or hospitalization. Site-specific conditional logistic regression models were used to explore the association between sanitation and hygiene exposures and MSD. Most households at six sites (>93%) had access to a sanitation facility, while 70% of households in rural Kenya had access to a facility. Practicing open defecation was a risk factor for MSD in children <5 y old in Kenya. Sharing sanitation facilities with 1-2 or ≥3 other households was a statistically significant risk factor for MSD in Kenya, Mali, Mozambique, and Pakistan. Among those with a designated handwashing area near the home, soap or ash were more frequently observed at control households and were significantly protective against MSD in Mozambique and India. This study suggests that sharing a sanitation facility with just one to two other households can increase the risk of MSD in young children, compared to using a private facility. Interventions aimed at increasing access to private household sanitation facilities may reduce the burden of MSD in children. These findings support the current World Health Organization/ United Nations Children's Emergency Fund (UNICEF) system that categorizes shared sanitation as unimproved.

The effects of long-duration space exposure on the mechanical properties of some carbon-reinforced resin matrix composites

NASA Technical Reports Server (NTRS)

Vyhnal, Richard F.

1993-01-01

Long Duration Exposure Facility (LDEF) Experiment A0175 involved the non-instrumented exposure of seven carbon-fiber reinforced resin-matrix advanced composite panels contained in two trays - A7 and A1. These two trays were located, respectively, on the leading and trailing faces of LDEF, obliquely oriented to the RAM (Row 9) and WAKE (Row 3) directions. The identity and location of the seven panels, which consisted of six flat laminates of the following material systems are shown: carbon/epoxy (T300/934), carbon/bismaleimide (T300/F178), and carbon/polyimide (C6000/LARC-160 and C6000/PMR-15), plus one bonded honeycomb sandwich panel (T300/934 face sheets and Nomex core) patterned after the Space Shuttle payload bay door construction. These material systems were selected to represent a range of then-available matrix resins which, by virtue of their differing polymer chemistry, could conceivably exhibit differing susceptibility to the low-earth orbit (LEO) environment. The principal exposure conditions of the LDEF environment at these tray locations are shown. Noteworthy to some of the observations discussed is the four-orders-of magnitude difference in the atomic oxygen (AO) fluence, which made a shallow incidence angle (approximately 22 deg) to Tray A7, while Tray A1 on the trailing face was essentially shielded from AO exposure. This evaluation focused on determining the individual and relative suitability of a variety of resin-matrix composite systems for long-term space structural applications. This was accomplished primarily by measuring and comparing a range of engineering mechanical properties on over 300 test coupons sectioned from the flight panels and from identical control panels, and tested at ambient and elevated temperatures. This testing was supported by limited physical characterization, involving visual examination of flight panel surface features, measurements of weight loss and warpage, and examination for changes in internal integrity (micro cracking, delamination) by ultrasonic c-scan and polished cross-sections.

The association of prenatal media marketing exposure recall with breastfeeding intentions, initiation, and duration.

PubMed

Zhang, Yuanting; Carlton, Ewa; Fein, Sara B

2013-11-01

Infant formula marketing, either directly to consumers or through health care providers, may influence women's breastfeeding intentions, initiation, and duration. However, little is known about the impact of different types of media marketing on infant feeding intentions and behavior. This study investigated whether different types of recalled prenatal media marketing exposure to formula and breastfeeding information are related to breastfeeding intentions and behavior. Data were from the Infant Feeding Practices Study II, a longitudinal study from pregnancy through the infants' first year. Sample sizes ranged from 1384 to 2530. Negative binomial, logistic regression, and survival models were used to examine associations between recalled prenatal exposure to formula or breastfeeding information and breastfeeding intentions and behavior. Exposure to infant formula information from print media was associated with shorter intended duration of exclusive breastfeeding, and formula information from websites was related to lower odds of both intended and actual initiation. Exposure to breastfeeding information from websites was related to higher odds of both intended and actual initiation and longer intended duration of any breastfeeding. Breastfeeding information from print media was associated with longer duration of any breastfeeding, but information from broadcast media was associated with shorter duration of any breastfeeding. Mothers who recall exposure to formula information from print or websites are more likely to intend to use formula or to intend to use formula earlier and are less likely to initiate breastfeeding than mothers who do not recall seeing such information.

Modeling cumulative dose and exposure duration provided insights regarding the associations between benzodiazepines and injuries.

PubMed

Abrahamowicz, Michal; Bartlett, Gillian; Tamblyn, Robyn; du Berger, Roxane

2006-04-01

Accurate assessment of medication impact requires modeling cumulative effects of exposure duration and dose; however, postmarketing studies usually represent medication exposure by baseline or current use only. We propose new methods for modeling various aspects of medication use history and employment of them to assess the adverse effects of selected benzodiazepines. Time-dependent measures of cumulative dose or duration of use, with weighting of past exposures by recency, were proposed. These measures were then included in alternative versions of the multivariable Cox model to analyze the risk of fall related injuries among the elderly new users of three benzodiazepines (nitrazepam, temazepam, and flurazepam) in Quebec. Akaike's information criterion (AIC) was used to select the most predictive model for a given benzodiazepine. The best-fitting model included a combination of cumulative duration and current dose for temazepam, and cumulative dose for flurazepam and nitrazepam, with different weighting functions. The window of clinically relevant exposure was shorter for flurazepam than for the two other products. Careful modeling of the medication exposure history may enhance our understanding of the mechanisms underlying their adverse effects.

The Latest Developments in NASA's Long Duration Balloon Systems

NASA Astrophysics Data System (ADS)

Stilwell, Bryan D.

The Latest Developments in NASA’s Long Duration Balloon Systems Bryan D. Stilwell, bryan.stilwell@csbf.nasa.gov Columbia Scientific Balloon Facility, Palestine, Texas, USA The Columbia Scientific Balloon Facility, located in Palestine, Texas offers the scientific community a high altitude balloon based communications platform. Scientific payload mass can exceed 2722 kg with balloon float altitudes on average of 40000 km and flight duration of up to 100 days. Many developments in electrical systems have occurred over the more than 25 years of long duration flights. This paper will discuss the latest developments in electronic systems related to long duration flights. Over the years, the long duration flights have increased in durations exceeding 56 days. In order to support these longer flights, the systems have had to increase in complexity and reliability. Several different systems that have been upgraded and/or enhanced will be discussed.

Micrometeoroid/space debris effects on materials

NASA Technical Reports Server (NTRS)

Zwiener, James M.; Finckenor, Miria M.

1993-01-01

The Long Duration Exposure Facility (LDEF) micrometeoroid/space debris impact data has been reduced in terms that are convenient for evaluating the overall quantitative effect on material properties. Impact crater flux has been evaluated as a function of angle from velocity vector and as a function of crater size. This data is combined with spall data from flight and ground testing to calculate effective solar absorption and emittance values versus time. Results indicate that the surface damage from micrometeoroid/space debris does not significantly affect the overall surface optical thermal physical properties. Of course the local damage around impact craters radically alter optical properties. Damage to composites and solar cells on an overall basis was minimal.

Radiation and temperature effects on LDEF fiber optic samples

NASA Technical Reports Server (NTRS)

Johnston, A. R.; Hartmayer, R.; Bergman, L. A.

1993-01-01

Results obtained from the JPL Fiber Optics Long Duration Exposure Facility (LDEF) Experiment since the June 1991 Experimenters' Workshop are addressed. Radiation darkening of laboratory control samples and the subsequent annealing was measured in the laboratory for the control samples. The long-time residual loss was compared to the LDEF flight samples and found to be in agreement. The results of laboratory temperature tests on the flight samples, extending over a period of about nine years, including the pre-flight and post-flight analysis periods, are described. The temperature response of the different cable samples varies widely, and appears in two samples to be affected by polymer aging. Conclusions to date are summarized.

Syncom 4 deploy, LDEF retrieval highlight 10-day Columbia flight

NASA Technical Reports Server (NTRS)

1989-01-01

The objectives of Space Shuttle Mission STS-32 are described along with major flight activities, prelaunch and launch operations, trajectory sequence of events, and landing and post-landing operations. The primary objectives of STS-32 are the deployment of a Navy synchronous communications satellite (Syncom 4) and the retrieval of the Long Duration Exposure Facility (LDEF) launched from the Challenger in April 1984. Secondary STS-32 payloads include a protein crystal growth experiment, the Fluids Experiment Apparatus (FEA) for the investigation of microgravity materials processing, the Mesoscale Lighting Experiment, the Latitude-Longitude Locator Experiment, the Americal Flight Echocardiograph, and an experiment to investigate neurospora circadian rhythms in a microgravity environment.

Low Earth orbital atomic oxygen micrometeoroid, and debris interactions with photovoltaic arrays

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Rutledge, Sharon K.; Degroh, Kim K.

1991-01-01

Polyimide Kapton solar array blankets can be protected from atomic oxygen in low earth orbit if SiO sub x thin film coatings are applied to their surfaces. The useful lifetime of a blanket protected in this manner strongly depends on the number and size of defects in the protective coatings. Atomic oxygen degradation is dominated by undercutting at defects in protective coatings caused by substrate roughness and processing rather than micrometeoroid or debris impacts. Recent findings from the Long Duration Exposure Facility (LDEF) and ground based studies show that interactions between atomic oxygen and silicones may cause grazing and contamination problems which may lead to solar array degradation.

Degradation of electro-optic components aboard LDEF

NASA Technical Reports Server (NTRS)

Blue, M. D.

1993-01-01

Remeasurement of the properties of a set of electro-optic components exposed to the low-earth environment aboard the Long Duration Exposure Facility (LDEF) indicates that most components survived quite well. Typical components showed some effects related to the space environment unless well protected. The effects were often small but significant. Results for semiconductor infrared detectors, lasers, and LED's, as well as filters, mirrors, and black paints are described. Semiconductor detectors and emitters were scarred but reproduced their original characteristics. Spectral characteristics of multi-layer dielectric filters and mirrors were found to be altered and degraded. Increased absorption in black paints indicates an increase in absorption sites, giving rise to enhanced performance as coatings for baffles and sunscreens.

Manual for LDEF tensile tests

NASA Technical Reports Server (NTRS)

Witte, W. G., Jr.

1985-01-01

One of the experiments aboard the NASA Long Duration Exposure Facility (LDEF) consists of a tray of approximately one hundred tensile specimens of several candidate space structure composite materials. During the LDEF flight the materials will be subjected to the space environment and to possible contamination during launch and recovery. Tensile tests of representative samples were made before the LDEF flight to obtain baseline data. Similar tests will be made on control specimens stored on earth for the length of the LDEF flight and on recovered flight specimens. This manual codifies the details of testing, data acquisition, and handling used in obtaining the baseline data so that the same procedures and equipment will be used on the subsequent tests.

Regular cannabis and alcohol use is associated with resting-state time course power spectra in incarcerated adolescents.

PubMed

Thijssen, Sandra; Rashid, Barnaly; Gopal, Shruti; Nyalakanti, Prashanth; Calhoun, Vince D; Kiehl, Kent A

2017-09-01

Cannabis and alcohol are believed to have widespread effects on the brain. Although adolescents are at increased risk for substance use, the adolescent brain may also be particularly vulnerable to the effects of drug exposure due to its rapid maturation. Here, we examined the association between cannabis and alcohol use duration and resting-state functional connectivity in a large sample of male juvenile delinquents. The present sample was drawn from the Southwest Advanced Neuroimaging Cohort, Youth sample, and from a youth detention facility in Wisconsin. All participants were scanned at the maximum-security facilities using The Mind Research Network's 1.5T Avanto SQ Mobile MRI scanner. Information on cannabis and alcohol regular use duration was collected using self-report. Resting-state networks were computed using group independent component analysis in 201 participants. Associations with cannabis and alcohol use were assessed using Mancova analyses controlling for age, IQ, smoking and psychopathy scores in the complete case sample of 180 male juvenile delinquents. No associations between alcohol or cannabis use and network spatial maps were found. Longer cannabis use was associated with decreased low frequency power of the default mode network, the executive control networks (ECNs), and several sensory networks, and with decreased functional network connectivity. Duration of alcohol use was associated with decreased low frequency power of the right frontoparietal network, salience network, dorsal attention network, and several sensory networks. Our findings suggest that adolescent cannabis and alcohol use are associated with widespread differences in resting-state time course power spectra, which may persist even after abstinence. Copyright © 2017 Elsevier B.V. All rights reserved.

42 CFR 412.426 - Transition period.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Services of Inpatient Psychiatric Facilities § 412.426 Transition period. (a) Duration of transition period... psychiatric facility receives a payment comprised of a blend of the estimated Federal per diem payment amount... new inpatient psychiatric facilities. New inpatient psychiatric facilities, are facilities that under...

CS-duration and partial-reinforcement effects counteract overshadowing in select situations

PubMed Central

Urushihara, Kouji; Miller, Ralph R.

2008-01-01

Two experiments used rats in a conditioned lick suppression preparation to investigate how the conditioned stimulus (CS)-duration and partial-reinforcement effects (i.e., weakened responding due to conditioning with a CS of longer duration and presenting nonreinforced CSs intermingled with CS-unconditioned stimulus [US] pairings, respectively) interact with overshadowing. Experiment 1 found that when overshadowing treatment was combined with either extended CS duration or partial reinforcement, the response deficit was weaker than when either of these three treatments was administered alone. In Experiment 2, the generality of the findings in Experiment 1 was investigated by replicating it with various US-US intervals. This time counteraction was observed only when both the absolute duration of total CS exposure and the US-US interval were short. The results support neither the view that the ratio between the total CS exposure and total time in the context determines the CS-duration and the partial-reinforcement effects nor the view that these two effects arise from a loss of effectiveness of the excitatory CS-US association during CS-alone exposures in partial reinforcement or early periods of CS exposure with long CSs. PMID:18047218

Daytime Effect of Monochromatic Blue Light on EEG Activity Depends on Duration and Timing of Exposure in Young Men

PubMed Central

Iskra-Golec, Irena; Golonka, Krystyna; Wyczesany, Miroslaw; Smith, Lawrence; Siemiginowska, Patrycja; Wątroba, Joanna

2017-01-01

Growing evidence suggests an alerting effect of monochromatic blue light on brain activity. Little is known about the moderation of those effects by timing and duration of exposure. The present electroencephalography (EEG ) study examined such moderations on delta, theta, alpha1, alpha2, and beta EEG bands. A counterbalanced repeated-measures design was applied. The 16-hr daytime period was divided into three sessions: 07:00-12:20, 12:20-17:40, and 17:40-23:00 (timing of exposure). Two light conditions comparable in luminance but differing in wavelength were applied, namely polychromatic white light and monochromatic blue light (460 nm). There were two durations of exposure—the shorter one lasting 30 min and the longer one lasting 4 hrs. Thirty male students participated in the study. Four factors analyses of variance (ANOV As, for light conditions, timing of exposure, duration of exposure, and brain area) were performed on each EEG band. Results indicated an alerting effect of short exposure to monochromatic blue light at midday and in the evening, which was demonstrated by a decrease in lower frequency bands (alpha1, delta, and theta, respectively). Long exposure to blue light may have a reverse effect, especially in the morning and at midday, when increases in lower frequency bands (theta in the morning and theta and alpha1 at midday) were observed. It can be concluded that the daytime effect of monochromatic blue light on EEG activity depends on timing and duration of exposure. PMID:29062437

Environmental Durability Issues for Solar Power Systems in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Degroh, Kim K.; Banks, Bruce A.; Smith, Daniela C.

1994-01-01

Space solar power systems for use in the low Earth orbit (LEO) environment experience a variety of harsh environmental conditions. Materials used for solar power generation in LEO need to be durable to environmental threats such as atomic oxygen, ultraviolet (UV) radiation, thermal cycling, and micrometeoroid and debris impact. Another threat to LEO solar power performance is due to contamination from other spacecraft components. This paper gives an overview of these LEO environmental issues as they relate to space solar power system materials. Issues addressed include atomic oxygen erosion of organic materials, atomic oxygen undercutting of protective coatings, UV darkening of ceramics, UV embrittlement of Teflon, effects of thermal cycling on organic composites, and contamination due to silicone and organic materials. Specific examples of samples from the Long Duration Exposure Facility (LDEF) and materials returned from the first servicing mission of the Hubble Space Telescope (HST) are presented. Issues concerning ground laboratory facilities which simulate the LEO environment are discussed along with ground-to-space correlation issues.

Bioaccumulation factors and the steady state assumption for cesium isotopes in aquatic foodwebs near nuclear facilities.

PubMed

Rowan, D J

2013-07-01

Steady state approaches, such as transfer coefficients or bioaccumulation factors, are commonly used to model the bioaccumulation of (137)Cs in aquatic foodwebs from routine operations and releases from nuclear generating stations and other nuclear facilities. Routine releases from nuclear generating stations and facilities, however, often consist of pulses as liquid waste is stored, analyzed to ensure regulatory compliance and then released. The effect of repeated pulse releases on the steady state assumption inherent in the bioaccumulation factor approach has not been evaluated. In this study, I examine the steady state assumption for aquatic biota by analyzing data for two cesium isotopes in the same biota, one isotope in steady state (stable (133)Cs) from geologic sources and the other released in pulses ((137)Cs) from reactor operations. I also compare (137)Cs bioaccumulation factors for similar upstream populations from the same system exposed solely to weapon test (137)Cs, and assumed to be in steady state. The steady state assumption appears to be valid for small organisms at lower trophic levels (zooplankton, rainbow smelt and 0+ yellow perch) but not for older and larger fish at higher trophic levels (walleye). Attempts to account for previous exposure and retention through a biokinetics approach had a similar effect on steady state, upstream and non-steady state, downstream populations of walleye, but were ineffective in explaining the more or less constant deviation between fish with steady state exposures and non-steady state exposures of about 2-fold for all age classes of walleye. These results suggest that for large, piscivorous fish, repeated exposure to short duration, pulse releases leads to much higher (137)Cs BAFs than expected from (133)Cs BAFs for the same fish or (137)Cs BAFs for similar populations in the same system not impacted by reactor releases. These results suggest that the steady state approach should be used with caution in any situation where reactor releases are episodic or pulse in nature, even if the magnitude of these releases is small. Copyright © 2012. Published by Elsevier Ltd.

Photochemical mechanisms of ocular photic injury (Abstract Only)

NASA Astrophysics Data System (ADS)

Stuck, Bruce E.; Lund, David J.; Zuclich, Joseph A.

2000-03-01

Mechanisms of photic injury to the eye can be categorized as photochemical, photothermal or photodistruptive. Exposure wavelength, exposure duration, ocular tissue characteristics and response criteria are key factors in the delineation of the ocular injury mechanisms. Depending on the exposure condition, one or all of the laser-tissue interaction mechanisms can be involved. Although photic injury to the eye was initially assumed to involve thermal mechanisms, more recent research has demonstrated that ocular effects can be produced by light exposure without a significant retinal temperature rise. Photochemical mechanisms are also implicated in UV photic injury to the cornea and lens. Exposure of the retina to short visible wavelengths for prolonged durations results in photochemical retinal damage with negligible localized retinal temperature elevation. For exposure conditions where photochemical mechanisms are dominate, the reciprocity of irradiance and exposure duration is apparent. The latency until observation of a photochemical lesion is often 24-48 hours whereas a thermal lesion is observed immediately or within a few hours after the exposure. Action spectra for photochemical injury to the eye are discussed in the context of ocular injury thresholds and current permissible exposure limits.

Structural materials for space applications

NASA Technical Reports Server (NTRS)

Tenney, Darrel R.

1989-01-01

The long-term performance of structural materials in the space environment is a key research activity within NASA. The primary concerns for materials in low Earth orbit (LEO) are atomic oxygen erosion and space debris impact. Atomic oxygen studies have included both laboratory exposures in atomic oxygen facilities and flight exposures using the Shuttle. Characterization of atomic oxygen interaction with materials has included surface recession rates, residual mechanical properties, optical property measurements, and surface analyses to establish chemical changes. The Long Duration Exposure Facility (LDEF) is scheduled to be retrieved in 1989 and is expected to provide a wealth of data on atomic oxygen erosion in space. Hypervelocity impact studies have been conducted to establish damage mechanisms and changes in mechanical properties. Samples from LDEF will be analyzed to determine the severity of space debris impact on coatings, films, and composites. Spacecraft placed in geosynchronous Earth orbit (GEO) will be subjected to high doses of ionizing radiation which for long term exposures will exceed the damage threshold of many polymeric materials. Radiation interaction with polymers can result in chain scission and/or cross-linking. The formation of low molecular weight products in the epoxy plasticize the matrix at elevated temperatures and embrittle the matrix at low temperatures. This affects both the matrix-dominated mechanical properties and the dimensional stability of the composite. Embrittlement of the matrix at low temperatures results in enhanced matrix microcracking during thermal cycling. Matrix microcracking changes the coefficient of thermal expansion (CTE) of composite laminates and produces permanent length changes. Residual stress calculations were performed to estimate the conditions necessary for microcrack development in unirradiated and irradiated composites. The effects of UV and electron exposure on the optical properties of transparent polymer films were also examined to establish the optimum chemical structure for good radiation resistance. Thoughts on approaches to establishing accelerated testing procedures are discussed.

Respirator use and its impact on particulate matter exposure in aluminum manufacturing facilities.

PubMed

Liu, Sa; Noth, Elizabeth; Eisen, Ellen; Cullen, Mark R; Hammond, Katharine

2018-05-31

Objectives As part of a large epidemiologic study of particulate health effect, this study aimed to report respirator use among total particulate matter (TPM) samples collected in a major aluminum manufacturing company from 1966‒2013 and evaluate the impact of respirator-use adjustment on exposure estimation. Methods Descriptive analyses were performed to evaluate respirator use across facilities and by facility type and job. Protection factors were applied to TPM measurements for recorded respirator use. Estimated TPM exposure for each job ‒ before and after respirator-use adjustment ‒ were compared to assess the impact of adjustment on exposure estimation. Results Respirator use was noted for 37% of 12 402 full-shift personal TPM samples. Measured TPM concentration ranged from less than detectable to 8220 mg/m3, with arithmetic mean, median and standard deviation being 10.6, 0.87 and 130 mg/m 3 , respectively. Respirators were used more often in smelting facilities (52% of TPM measurements) than in fabricating (17%) or refinery facilities (28%) (P<0.01). Sixty-two percent of jobs in smelting facilities were subject to respirator-use adjustment, whereas it was 20% and 70% in fabricating and refinery facilities, respectively. Applying protection factors to TPM measurements significantly reduced estimated job mean TPM exposures and changed exposure categories in these facilities, with larger impact in smelting than fabricating facilities. Conclusions Respirator use varied by time, facility and job. Adjusting respirator use resulted in differential impact in smelting and fabricating facilities, which will need to be incorporated into ongoing epidemiologic studies accordingly.

Human responses to bright light of different durations.

PubMed

Chang, Anne-Marie; Santhi, Nayantara; St Hilaire, Melissa; Gronfier, Claude; Bradstreet, Dayna S; Duffy, Jeanne F; Lockley, Steven W; Kronauer, Richard E; Czeisler, Charles A

2012-07-01

Light exposure in the early night induces phase delays of the circadian rhythm in melatonin in humans. Previous studies have investigated the effect of timing, intensity, wavelength, history and pattern of light stimuli on the human circadian timing system. We present results from a study of the duration–response relationship to phase-delaying bright light. Thirty-nine young healthy participants (16 female; 22.18±3.62 years) completed a 9-day inpatient study. Following three baseline days, participants underwent an initial circadian phase assessment procedure in dim light (<3 lux), and were then randomized for exposure to a bright light pulse (∼10,000 lux) of 0.2 h, 1.0 h, 2.5 h or 4.0 h duration during a 4.5 h controlled-posture episode centred in a 16 h wake episode. After another 8 h sleep episode, participants completed a second circadian phase assessment. Phase shifts were calculated from the difference in the clock time of the dim light melatonin onset (DLMO) between the initial and final phase assessments. Exposure to varying durations of bright light reset the circadian pacemaker in a dose-dependent, non-linear manner. Per minute of exposure, the 0.2 h duration was over 5 times more effective at phase delaying the circadian pacemaker (1.07±0.36 h) as compared with the 4.0 h duration (2.65±0.24 h). Acute melatonin suppression and subjective sleepiness also had a dose-dependent response to light exposure duration. These results provide strong evidence for a non-linear resetting response of the human circadian pacemaker to light duration.

Space life sciences perspectives for Space Station Freedom

NASA Technical Reports Server (NTRS)

Young, Laurence R.

1992-01-01

It is now generally acknowledged that the life science discipline will be the primary beneficiary of Space Station Freedom. The unique facility will permit advances in understanding the consequences of long duration exposure to weightlessness and evaluation of the effectiveness of countermeasures. It will also provide an unprecedented opportunity for basic gravitational biology, on plants and animals as well as human subjects. The major advantages of SSF are the long duration exposure and the availability of sufficient crew to serve as subjects and operators. In order to fully benefit from the SSF, life sciences will need both sufficient crew time and communication abilities. Unlike many physical science experiments, the life science investigations are largely exploratory, and frequently bring unexpected results and opportunities for study of newly discovered phenomena. They are typically crew-time intensive, and require a high degree of specialized training to be able to react in real time to various unexpected problems or potentially exciting findings. Because of the long duration tours and the large number of experiments, it will be more difficult than with Spacelab to maintain astronaut proficiency on all experiments. This places more of a burden on adequate communication and data links to the ground, and suggests the use of AI expert system technology to assist in astronaut management of the experiment. Typical life science experiments, including those flown on Spacelab Life Sciences 1, will be described from the point of view of the demands on the astronaut. A new expert system, 'PI in a Box,' will be introduced for SLS-2, and its applicability to other SSF experiments discussed. (This paper consists on an abstract and ten viewgraphs.)

Space life sciences perspectives for Space Station Freedom

NASA Astrophysics Data System (ADS)

Young, Laurence R.

It is now generally acknowledged that the life science discipline will be the primary beneficiary of Space Station Freedom. The unique facility will permit advances in understanding the consequences of long duration exposure to weightlessness and evaluation of the effectiveness of countermeasures. It will also provide an unprecedented opportunity for basic gravitational biology, on plants and animals as well as human subjects. The major advantages of SSF are the long duration exposure and the availability of sufficient crew to serve as subjects and operators. In order to fully benefit from the SSF, life sciences will need both sufficient crew time and communication abilities. Unlike many physical science experiments, the life science investigations are largely exploratory, and frequently bring unexpected results and opportunities for study of newly discovered phenomena. They are typically crew-time intensive, and require a high degree of specialized training to be able to react in real time to various unexpected problems or potentially exciting findings. Because of the long duration tours and the large number of experiments, it will be more difficult than with Spacelab to maintain astronaut proficiency on all experiments. This places more of a burden on adequate communication and data links to the ground, and suggests the use of AI expert system technology to assist in astronaut management of the experiment. Typical life science experiments, including those flown on Spacelab Life Sciences 1, will be described from the point of view of the demands on the astronaut. A new expert system, 'PI in a Box,' will be introduced for SLS-2, and its applicability to other SSF experiments discussed. (This paper consists on an abstract and ten viewgraphs.)

Ground-based simulation of LEO environment: Investigations of a select LDEF material: FEP Teflon (trademark)

NASA Technical Reports Server (NTRS)

Cross, Jon B.; Koontz, Steven L.

1993-01-01

The Long Duration Exposure Facility (LDEF) has produced a wealth of data on materials degradation in the low earth orbit (LEO) space environment and has conclusively shown that surface chemistry (as opposed to surface physics-sputtering) is the key to understanding and predicting the degradation of materials in the LEO environment. It is also clear that materials degradation and spacecraft contamination are closely linked and that the fundamental mechanisms responsible for this linking are in general not well understood especially in the area of synergistic effects. The study of the fundamental mechanisms underlying materials degradation in LEO is hampered by the fact that the degradation process itself is not observed during the actual exposure to the environment. Rather the aftermath of the degradation process is studied, i.e., the material that remains after exposure is observed and mechanisms are proposed to explain the observed results. The EOIM-3 flight experiment is an attempt to bring sophisticated diagnostic equipment into the space environment and monitor the degradation process in real time through the use of mass spectrometry. More experiments of this nature which would include surface sensitive diagnostics (Auger and photoelectron spectroscopes) are needed to truly unravel the basic chemical mechanisms involved in the materials degradation process. Since these in-space capabilities will most likely not be available in the near future, ground-based LEO simulation facilities employing sophisticated diagnostics are needed to further advance the basic understanding of the materials degradation mechanisms. The LEO simulation facility developed at Los Alamos National Laboratory has been used to investigate the atomic oxygen/vacuum ultraviolet (AO/VUV) enhanced degradation of FEP Teflon. The results show that photo-ejection of polymer fragments occur at elevated temperature (200 C), that VUV synergistic rare gas sputtering of polymer fragments occur even at 25 C, and that combined OA/VUV interaction produces a wide variety of gas phase reaction products.

MISSE Results Used for RF Plasma Ground Testing-To-Space-Exposure Correlation for Coated Kapton

NASA Technical Reports Server (NTRS)

Miller, Sharon K. R.; Banks, Bruce A.; Tollis, Greg

2008-01-01

The ability to predict the durability of materials in the low Earth orbit (LEO) environment by exposing them in ground-based facilities is important because one can achieve test results sooner, expose more types of materials, and do it much more cost effectively than to test them in flight. However, flight experiments to determine the durability of groups or classes of materials that behave similarly are needed in order to provide correlations of how much time in ground-based facilities represents certain durations in LEO for the material type of interest. An experiment was designed and flown on the Materials International Space Station Experiment (MISSE) 2 (3.95 yr in LEO) and MISSE 4 (1.04 yr in LEO) in order to develop this type of correlation between ground-based RF plasma exposure and LEO exposure for coated Kapton. The experiment consisted of a sample of Kapton H (DuPont) polyimide coated with 1300 of silicon dioxide by Sheldahl, Inc. The samples were exposed to atomic oxygen in a radio frequency (RF) generated atomic oxygen plasma. Mass change was measured for the samples and then the same samples were exposed in flight on MISSE and the mass change was again recorded post-flight. After documentation, the samples were exposed again in the ground-based RF plasma in order to determine if the erosion would be the same as it had been in the same facility pre-flight which would indicate whether or not the sample had been damaged during flight and if the defects on the surface were those that were there preflight. The slopes of the mass change versus fluence plots were then used to develop a correlation factor that can be used to help predict the durability of coated Kapton in ground-based isotropic atomic oxygen plasma systems. This paper describes the experiment and presents the correlation factor results.

Secondhand tobacco smoke exposure and pulmonary function: a cross-sectional study among non-smoking employees of bar and restaurants in Santiago, Chile.

PubMed

Parro, Javiera; Aceituno, Paulina; Droppelmann, Andrea; Mesías, Sthepanie; Muñoz, Claudio; Marchetti, Nella; Iglesias, Verónica

2017-10-06

The workplace remains a significant source of secondhand smoke (SHS) exposure. This pollutant is known to be associated with respiratory and cardiovascular problems, but its effects on specific pulmonary function parameters remain largely unexplored. The objectives of this study were to measure SHS exposure among non-smoking employees of bar and restaurants in Santiago, Chile and to evaluate the effects of such exposure on pulmonary function. Cross-sectional design. The study sample included non-smoking workers from 57 restaurants and bars in Santiago, Chile. The outcome variable was pulmonary function and the exposure variables were urine cotinine concentration, a biomarker for current SHS exposure, and years of SHS exposure in the workplace as proxy of chronic exposure. Personal and occupational variables were also recorded. Data analysis was performed using linear regression models adjusted by confounders. The median age of the workers was 35 years and the median employment duration at the analysed venues was 1 year. Workers in smoking facilities reported greater SHS exposure (36 hours per week) than workers in smoke-free locations (4 hours per week). Urine cotinine levels were inversely correlated with forced vital capacity, but the finding was not statistically significant (β=-0.0002; 95% CI -0.007 to 0.006). Years of exposure to SHS showed to be significantly associated with forced expiratory flow 25/75 (β=-0.006; 95% CI -0.010 to -0.0004). These findings suggest that cumulative exposure to SHS at work may contribute to deterioration of pulmonary function in non-smoking employees. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Secondhand tobacco smoke exposure and pulmonary function: a cross-sectional study among non-smoking employees of bar and restaurants in Santiago, Chile

PubMed Central

Parro, Javiera; Aceituno, Paulina; Droppelmann, Andrea; Mesías, Sthepanie; Muñoz, Claudio; Marchetti, Nella; Iglesias, Verónica

2017-01-01

Introduction The workplace remains a significant source of secondhand smoke (SHS) exposure. This pollutant is known to be associated with respiratory and cardiovascular problems, but its effects on specific pulmonary function parameters remain largely unexplored. The objectives of this study were to measure SHS exposure among non-smoking employees of bar and restaurants in Santiago, Chile and to evaluate the effects of such exposure on pulmonary function. Methods Cross-sectional design. The study sample included non-smoking workers from 57 restaurants and bars in Santiago, Chile. The outcome variable was pulmonary function and the exposure variables were urine cotinine concentration, a biomarker for current SHS exposure, and years of SHS exposure in the workplace as proxy of chronic exposure. Personal and occupational variables were also recorded. Data analysis was performed using linear regression models adjusted by confounders. Results The median age of the workers was 35 years and the median employment duration at the analysed venues was 1 year. Workers in smoking facilities reported greater SHS exposure (36 hours per week) than workers in smoke-free locations (4 hours per week). Urine cotinine levels were inversely correlated with forced vital capacity, but the finding was not statistically significant (β=−0.0002; 95% CI −0.007 to 0.006). Years of exposure to SHS showed to be significantly associated with forced expiratory flow25/75 (β=−0.006; 95% CI −0.010 to −0.0004). Conclusion These findings suggest that cumulative exposure to SHS at work may contribute to deterioration of pulmonary function in non-smoking employees. PMID:28988182

Anodized aluminum on LDEF

NASA Technical Reports Server (NTRS)

Golden, Johnny L.

1993-01-01

A compilation of reported analyses and results obtained for anodized aluminum flown on the Long Duration Exposure Facility (LDEF) was prepared. Chromic acid, sulfuric acid, and dyed sulfuric acid anodized surfaces were exposed to the space environment. The vast majority of the anodized surface on LDEF was chromic acid anodize because of its selection as a thermal control coating for use on the spacecraft primary structure, trays, tray clamps, and space end thermal covers. Reports indicate that the chromic acid anodize was stable in solar absorptance and thermal emittance, but that contamination effects caused increases in absorptance on surfaces exposed to low atomic oxygen fluences. There were some discrepancies, however, in that some chromic acid anodized specimens exhibited significant increases in absorptance. Sulfuric acid anodized surfaces also appeared stable, although very little surface area was available for evaluation. One type of dyed sulfuric acid anodize was assessed as an optical baffle coating and was observed to have improved infrared absorptance characteristics with exposure on LDEF.

LDEF data correlation to existing NASA debris environment models

NASA Technical Reports Server (NTRS)

Atkinson, Dale R.; Allbrooks, Martha K.; Watts, Alan J.

1992-01-01

The Long Duration Exposure Facility (LDEF) was recovered in January 1990, following 5.75 years exposure of about 130 sq. m to low-Earth orbit. About 25 sq. m of this surface area was aluminum 6061 T-6 exposed in every direction. In addition, about 17 sq. m of Scheldahl G411500 silver-Teflon thermal control blankets were exposed in 9 of the 12 directions. Since the LDEF was gravity gradient stabilized and did not rotate, the directional dependence of the flux can be easily distinguished. During the disintegration of the LDEF, all impact features larger than 0.5 mm into aluminum were documented for diameters and locations. In addition, the diameters and locations of all impact features larger than 0.3 mm into Scheldahl G411500 thermal control blankets were also documented. This data, along with additional information collected from LDEF materials will be compared with current meteoroid and debris models. This comparison will provide a validation of the models and will identify discrepancies between the models and the data.

NASA's Space Environments and Effects (SEE) Program: Contamination Engineering Technology Development

NASA Technical Reports Server (NTRS)

Pearson, Steven D.; Clifton, K. Stuart

1999-01-01

ABSTRACT The return of the Long Duration Exposure Facility (LDEF) in 1990 brought a wealth of space exposure data on materials, paints, solar cells, etc. and data on the many space environments. The effects of the harsh space environments can provide damaging or even disabling effects on spacecraft, its materials, and its instruments. In partnership with industry, academia, and other government agencies, National Aeronautics & Space Administration's (NASA's) Space Environments & Effects (SEE) Program defines the space environments and provides technology development to accommodate or mitigate these harmful environments on the spacecraft. This program provides a very comprehensive and focused approach to understanding the space environment, to define the best techniques for both flight and ground-based experimentation, to update the models which predict both the environments and the environmental effects on spacecraft, and finally to ensure that this information is properly maintained and inserted into spacecraft design programs. This paper will describe the current SEE Program and will present SEE contamination engineering technology development and risk mitigation for future spacecraft design.

NASA's Space Environments and Effects (SEE) program: contamination engineering technology development

NASA Astrophysics Data System (ADS)

Pearson, Steven D.; Clifton, K. Stuart

1999-10-01

The return of the Long Duration Exposure Facility (LDEF) in 1990 brought a wealth of space exposure data on materials, paints, solar cells, etc. and data on the many space environments. The effects of the harsh space environments can provide damaging or even disabling effects on spacecraft, its materials, and its instruments. In partnership with industry, academia, and other government agencies, National Aeronautics & Space Administration's (NASA's) Space Environments & Effects (SEE) Program defines the space environments and provides technology development to accommodate or mitigate these harmful environments on the spacecraft. This program provides a very comprehensive and focused approach to understanding the space environment, to define the best techniques for both flight and ground-based experimentation, to update the models which predict both the environments and the environmental effects on spacecraft, and finally to ensure that this information is properly maintained and inserted into spacecraft design programs. This paper will describe the current SEE Program and will present SEE contamination engineering technology development and risk mitigation for future spacecraft design.

Advances in boronization on NSTX-Upgrade

DOE PAGES

Skinner, C. H.; Bedoya, F.; Scotti, F.; ...

2017-01-27

Boronization has been effective in reducing plasma impurities and enabling access to higher density, higher confinement plasmas in many magnetic fusion devices. The National Spherical Torus eXperiment, NSTX, has recently undergone a major upgrade to NSTX-U in order to develop the physics basis for a ST-based Fusion Nuclear Science Facility (FNSF) with capability for double the toroidal field, plasma current, and NBI heating power and increased pulse duration from 1–1.5 s to 5–8 s. A new deuterated tri-methyl boron conditioning system was implemented together with a novel surface analysis diagnostic. We report on the spatial distribution of the boron depositionmore » versus discharge pressure, gas injection and electrode location. The oxygen concentration of the plasma facing surface was measured by in-vacuo XPS and increased both with plasma exposure and with exposure to trace residual gases. Furthermore, this increase correlated with the rise of oxygen emission from the plasma.« less

The Diesel Exhaust in Miners Study: II. Exposure monitoring surveys and development of exposure groups.

PubMed

Coble, Joseph B; Stewart, Patricia A; Vermeulen, Roel; Yereb, Daniel; Stanevich, Rebecca; Blair, Aaron; Silverman, Debra T; Attfield, Michael

2010-10-01

Air monitoring surveys were conducted between 1998 and 2001 at seven non-metal mining facilities to assess exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), for an epidemiologic study of miners exposed to DE. Personal exposure measurements were taken on workers in a cross-section of jobs located underground and on the surface. Air samples taken to measure REC were also analyzed for respirable organic carbon (ROC). Concurrent measurements to assess exposure to nitric oxide (NO) and nitrogen dioxide (NO₂), two gaseous components of DE, were also taken. The REC measurements were used to develop quantitative estimates of average exposure levels by facility, department, and job title for the epidemiologic analysis. Each underground job was assigned to one of three sets of exposure groups from specific to general: (i) standardized job titles, (ii) groups of standardized job titles combined based on the percentage of time in the major underground areas, and (iii) larger groups based on similar area carbon monoxide (CO) air concentrations. Surface jobs were categorized based on their use of diesel equipment and proximity to DE. A total of 779 full-shift personal measurements were taken underground. The average REC exposure levels for underground jobs with five or more measurements ranged from 31 to 58 μg m⁻³ at the facility with the lowest average exposure levels and from 313 to 488 μg m⁻³ at the facility with the highest average exposure levels. The average REC exposure levels for surface workers ranged from 2 to 6 μg m⁻³ across the seven facilities. There was much less contrast in the ROC compared with REC exposure levels measured between surface and underground workers within each facility, as well as across the facilities. The average ROC levels underground ranged from 64 to 195 μg m⁻³, while on the surface, the average ROC levels ranged from 38 to 71 μg m⁻³ by facility, an ∼2- to 3-fold difference. The average NO and NO₂ levels underground ranged from 0.20 to 1.49 parts per million (ppm) and from 0.10 to 0.60 ppm, respectively, and were ∼10 times higher than levels on the surface, which ranged from 0.02 to 0.11 ppm and from 0.01 to 0.06 ppm, respectively. The ROC, NO, and NO₂ concentrations underground were correlated with the REC levels (r = 0.62, 0.71, and 0.62, respectively). A total of 80% of the underground jobs were assigned an exposure estimate based on measurements taken for the specific job title or for other jobs with a similar percentage of time spent in the major underground work areas. The average REC exposure levels by facility were from 15 to 64 times higher underground than on the surface. The large contrast in exposure levels measured underground versus on the surface, along with the differences between the mining facilities and between underground jobs within the facilities resulted in a wide distribution in the exposure estimates for evaluation of exposure-response relationships in the epidemiologic analyses.

Passive exposure of Earth radiation budget experiment components LDEF experiment AO-147: Post-flight examinations and tests

NASA Technical Reports Server (NTRS)

Hickey, John R.

1991-01-01

The Passive Exposure of Earth Radiation Budget Experiment Components (PEERBEC) experiment of the Long Duration Exposure Facility (LDEF) mission was composed of sensors and components associated with the measurement of the earth radiation budget (ERB) from satellites. These components included the flight spare sensors from the ERB experiment which operated on Nimbus 6 and 7 satellites. The experiment components and materials as well as the pertinent background and ancillary information necessary for the understanding of the intended mission and the results are described. The extent and timing of the LDEF mission brought the exposure from solar minimum between cycles 21 and 22 through the solar maximum of cycle 22. The orbital decay, coupled with the events of solar maximum, caused the LDEF to be exposed to a broader range of space environmental effects than were anticipated. The mission spanned almost six years concurrent with the 12 year (to date) Nimbus 7 operations. Preliminary information is presented on the following: (1) the changes in transmittance experienced by the interference filters; (2) the results of retesting of the thermopile sensors, which appear to be relatively unaffected by the exposure; and (3) the results of the recalibration of the APEX cavity radiometer. The degradation and recovery of the filters of the Nimbus 7 ERB are also discussed relative to the apparent atomic oxygen cleaning which also applies to the LDEF.

Effects of Various Wavelength Ranges of Vacuum Ultraviolet Radiation on Teflon FEP Film Investigated

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; McCracken, Cara A.

2004-01-01

Teflon Fluorinated Ethylene Propylene (FTP) films (DuPont) have been widely used for spacecraft thermal control and have been observed to become embrittled and cracked upon exposure to the space environment. This degradation has been attributed to a synergistic combination of radiation and thermal effects. A research study was undertaken at the NASA Glenn Research Center to examine the effects of different wavelength ranges of vacuum ultraviolet (VUV) radiation on the degradation of the mechanical properties of FEP. This will contribute to an overall understanding of space radiation effects on Teflon FEP, and will provide information necessary to determine appropriate techniques for using laboratory tests to estimate space VUV degradation. Research was conducted using inhouse facilities at Glenn and was carried out, in part, through a grant with the Cleveland State University. Samples of Teflon FEP film of 50.8 microns thickness were exposed to radiation from a VUV lamp from beneath different cover windows to provide different exposure wavelength ranges: MgF2 (115 to 400 nm), crystalline quartz (140 to 400 nm), and fused silica (FS, 155 to 400 nm). Following exposure, FEP film specimens were tensile tested to determine the ultimate tensile strength and elongation at failure as a function of the exposure duration for each wavelength range. The graphs show the effect of ultraviolet exposure on the mechanical properties of the FEP samples.

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

PubMed Central

Kazmi, S. M. Shams; Balial, Satyajit; Dunn, Andrew K.

2014-01-01

Improved Laser Speckle Contrast Imaging (LSCI) blood flow analyses that incorporate inverse models of the underlying laser-tissue interaction have been used to develop more quantitative implementations of speckle flowmetry such as Multi-Exposure Speckle Imaging (MESI). In this paper, we determine the optimal camera exposure durations required for obtaining flow information with comparable accuracy with the prevailing MESI implementation utilized in recent in vivo rodent studies. A looping leave-one-out (LOO) algorithm was used to identify exposure subsets which were analyzed for accuracy against flows obtained from analysis with the original full exposure set over 9 animals comprising n = 314 regional flow measurements. From the 15 original exposures, 6 exposures were found using the LOO process to provide comparable accuracy, defined as being no more than 10% deviant, with the original flow measurements. The optimal subset of exposures provides a basis set of camera durations for speckle flowmetry studies of the microcirculation and confers a two-fold faster acquisition rate and a 28% reduction in processing time without sacrificing accuracy. Additionally, the optimization process can be used to identify further reductions in the exposure subsets for tailoring imaging over less expansive flow distributions to enable even faster imaging. PMID:25071956

Mortality among workers exposed to toluene diisocyanate in the US polyurethane foam industry: Update and exposure-response analyses.

PubMed

Pinkerton, Lynne E; Yiin, James H; Daniels, Robert D; Fent, Kenneth W

2016-08-01

Mortality among 4,545 toluene diisocyante (TDI)-exposed workers was updated through 2011. The primary outcome of interest was lung cancer. Life table analyses, including internal analyses by exposure duration and cumulative TDI exposure, were conducted. Compared with the US population, all cause and all cancer mortality was increased. Lung cancer mortality was increased but was not associated with exposure duration or cumulative TDI exposure. In post hoc analyses, lung cancer mortality was associated with employment duration in finishing jobs, but not in finishing jobs involving cutting polyurethane foam. Dermal exposure, in contrast to inhalational exposure, to TDI is expected to be greater in finishing jobs and may play a role in the observed increase in lung cancer mortality. Limitations include the lack of smoking data, uncertainty in the exposure estimates, and exposure estimates that reflected inhalational exposure only. Am. J. Ind. Med. 59:630-643, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Burning daylight: balancing vitamin D requirements with sensible sun exposure.

PubMed

Stalgis-Bilinski, Kellie L; Boyages, John; Salisbury, Elizabeth L; Dunstan, Colin R; Henderson, Stuart I; Talbot, Peter L

2011-04-04

To examine the feasibility of balancing sunlight exposure to meet vitamin D requirements with sun protection guidelines. We used standard erythemal dose and Ultraviolet Index (UVI) data for 1 June 1996 to 30 December 2005 for seven Australian cities to estimate duration of sun exposure required for fair-skinned individuals to synthesise 1000 IU (25 µg) of vitamin D, with 11% and 17% body exposure, for each season and hour of the day. Periods were classified according to whether the UVI was < 3 or ≥ 3 (when sun protection measures are recommended), and whether required duration of exposure was ≤ 30 min, 31-60 min, or > 60 min. Duration of sunlight exposure required to achieve 1000 IU of vitamin D synthesis. Duration of sunlight exposure required to synthesise 1000 IU of vitamin D varied by time of day, season and city. Although peak UVI periods are typically promoted as between 10 am and 3 pm, UVI was often ≥ 3 before 10 am or after 3 pm. When the UVI was < 3, there were few opportunities to synthesise 1000 IU of vitamin D within 30 min, with either 11% or 17% body exposure. There is a delicate line between balancing the beneficial effects of sunlight exposure while avoiding its damaging effects. Physiological and geographical factors may reduce vitamin D synthesis, and supplementation may be necessary to achieve adequate vitamin D status for individuals at risk of deficiency. ©The Medical Journal of Australia 2011

Childhood poverty and health: cumulative risk exposure and stress dysregulation.

PubMed

Evans, Gary W; Kim, Pilyoung

2007-11-01

A massive literature documents the inverse association between poverty or low socioeconomic status and health, but little is known about the mechanisms underlying this robust relation. We examined longitudinal relations between duration of poverty exposure since birth, cumulative risk exposure, and physiological stress in two hundred seven 13-year-olds. Chronic stress was assessed by basal blood pressure and overnight cortisol levels; stress regulation was assessed by cardiovascular reactivity to a standard acute stressor and recovery after exposure to this stressor. Cumulative risk exposure was measured by multiple physical (e.g., substandard housing) and social (e.g., family turmoil) risk factors. The greater the number of years spent living in poverty, the more elevated was overnight cortisol and the more dysregulated was the cardiovascular response (i.e., muted reactivity). Cardiovascular recovery was not affected by duration of poverty exposure. Unlike the duration of poverty exposure, concurrent poverty (i.e., during adolescence) did not affect these physiological stress outcomes. The effects of childhood poverty on stress dysregulation are largely explained by cumulative risk exposure accompanying childhood poverty.

Occupational Electromagnetic Field Exposures Associated with Sleep Quality: A Cross-Sectional Study

PubMed Central

Liu, Hui; Chen, Guangdi; Pan, Yifeng; Chen, Zexin; Jin, Wen; Sun, Chuan; Chen, Chunjing; Dong, Xuanjun; Chen, Kun; Xu, Zhengping; Zhang, Shanchun; Yu, Yunxian

2014-01-01

Background Exposure to electromagnetic field (EMF) emitted by mobile phone and other machineries concerns half the world’s population and raises the problem of their impact on human health. The present study aims to explore the effects of electromagnetic field exposures on sleep quality and sleep duration among workers from electric power plant. Methods A cross-sectional study was conducted in an electric power plant of Zhejiang Province, China. A total of 854 participants were included in the final analysis. The detailed information of participants was obtained by trained investigators using a structured questionnaire, which including socio-demographic characteristics, lifestyle variables, sleep variables and electromagnetic exposures. Physical examination and venous blood collection were also carried out for every study subject. Results After grouping daily occupational electromagnetic exposure into three categories, subjects with long daily exposure time had a significantly higher risk of poor sleep quality in comparison to those with short daily exposure time. The adjusted odds ratios were 1.68 (95%CI: 1.18, 2.39) and 1.57 (95%CI: 1.10, 2.24) across tertiles. Additionally, among the subjects with long-term occupational exposure, the longer daily occupational exposure time apparently increased the risk of poor sleep quality (OR (95%CI): 2.12 (1.23∼3.66) in the second tertile; 1.83 (1.07∼3.15) in the third tertile). There was no significant association of long-term occupational exposure duration, monthly electric fee or years of mobile-phone use with sleep quality or sleep duration. Conclusions The findings showed that daily occupational EMF exposure was positively associated with poor sleep quality. It implies EMF exposure may damage human sleep quality rather than sleep duration. PMID:25340654

Optimizing the interventional cardiology facility: services integration in routine workflow.

PubMed

Gortzis, Lefteris; Kalogeropoulos, A; Alexopoulos, D; Nikiforidis, G

2007-01-01

Integration of administrative and clinical data, imaging, and expert services, although challenging,is a key requirement in contemporary interventional cardiology facilities (ICF). We propose a workflow-oriented hybrid system to support the ICF and investigate its feasibility and effectiveness ina referral medical center. We have developed a Java-powered hybrid system (NetCARDIO), able to support over web synchronous and asynchronous data management, realtime multimedia data telemonitoring and continuous telementoring. Data regarding procedural rates, treatment planning and radiation exposure were collected over a two-year period of routine NetCARDIO implementation(July 2002 to June 2004) and compared with data from an immediately preceding period of equal duration (January 2000 to December 2001). During the NetCARDIO period, 163 +/- 17 coronary procedures per month were performed vs.77 +/- 15 during the control period (p <0.001). Percutaneous coronary intervention was delivered 'ad hoc' in 88% of eligible patients vs. 45% (p <0.001). Mean fluoroscopy time per coronary lesion treated decreased from 594 +/- 82 s to 540 +/- 94 s(p < 0.001). Annual radiation exposure of expert interventionists was decreased by 22%. Electronic storage significantly reduced archiving costs. Real-time multimodal services sharing combined with powerful database capabilities is feasible through a web-based structure, significantly enhancing performance and cost-effectiveness of ICF. Further research is needed to promote integration of additional data sources and services.

The Diesel Exhaust in Miners Study: II. Exposure Monitoring Surveys and Development of Exposure Groups

PubMed Central

Coble, Joseph B.; Stewart, Patricia A.; Vermeulen, Roel; Yereb, Daniel; Stanevich, Rebecca; Blair, Aaron; Silverman, Debra T.; Attfield, Michael

2010-01-01

Air monitoring surveys were conducted between 1998 and 2001 at seven non-metal mining facilities to assess exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), for an epidemiologic study of miners exposed to DE. Personal exposure measurements were taken on workers in a cross-section of jobs located underground and on the surface. Air samples taken to measure REC were also analyzed for respirable organic carbon (ROC). Concurrent measurements to assess exposure to nitric oxide (NO) and nitrogen dioxide (NO2), two gaseous components of DE, were also taken. The REC measurements were used to develop quantitative estimates of average exposure levels by facility, department, and job title for the epidemiologic analysis. Each underground job was assigned to one of three sets of exposure groups from specific to general: (i) standardized job titles, (ii) groups of standardized job titles combined based on the percentage of time in the major underground areas, and (iii) larger groups based on similar area carbon monoxide (CO) air concentrations. Surface jobs were categorized based on their use of diesel equipment and proximity to DE. A total of 779 full-shift personal measurements were taken underground. The average REC exposure levels for underground jobs with five or more measurements ranged from 31 to 58 μg m−3 at the facility with the lowest average exposure levels and from 313 to 488 μg m−3 at the facility with the highest average exposure levels. The average REC exposure levels for surface workers ranged from 2 to 6 μg m−3 across the seven facilities. There was much less contrast in the ROC compared with REC exposure levels measured between surface and underground workers within each facility, as well as across the facilities. The average ROC levels underground ranged from 64 to 195 μg m−3, while on the surface, the average ROC levels ranged from 38 to 71 μg m−3 by facility, an ∼2- to 3-fold difference. The average NO and NO2 levels underground ranged from 0.20 to 1.49 parts per million (ppm) and from 0.10 to 0.60 ppm, respectively, and were ∼10 times higher than levels on the surface, which ranged from 0.02 to 0.11 ppm and from 0.01 to 0.06 ppm, respectively. The ROC, NO, and NO2 concentrations underground were correlated with the REC levels (r = 0.62, 0.71, and 0.62, respectively). A total of 80% of the underground jobs were assigned an exposure estimate based on measurements taken for the specific job title or for other jobs with a similar percentage of time spent in the major underground work areas. The average REC exposure levels by facility were from 15 to 64 times higher underground than on the surface. The large contrast in exposure levels measured underground versus on the surface, along with the differences between the mining facilities and between underground jobs within the facilities resulted in a wide distribution in the exposure estimates for evaluation of exposure–response relationships in the epidemiologic analyses. PMID:20876232

Force Measurements in Short-Duration Hypersonic Facilities

DTIC Science & Technology

1975-11-01

method which depends upon a double differentiation of experimental data, albeit smoothed. When the motion is non -plarnar, the tricyclic method of...J.0. & Hamaker, F.M. An experimental investigation of the base pressure characteristics of (1955) non -lifting bodies of revolution at Mach numbers...AD-AO18 842 FORCE MEASUREMENTS IN SHORT-DURATION HYPERSONIC FACILITIES Leonard Bernstein, et al Advisory Group for Aerospace Research and Development

Degradation of FEP thermal control materials returned from the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Zuby, Thomas M.; Degroh, Kim K.; Smith, Daniela C.

1995-01-01

After an initial 3.6 years of space flight, the Hubble Space Telescope was serviced through a joint effort with the NASA and the European Space Agency. Multi-layer insulation (MLI) was retrieved from the electronics boxes of the two magnetic sensing systems (MSS), also called the magnetometers, and from the returned solar array (SA-I) drive arm assembly. The top layer of each MLI assembly is fluorinated ethylene propylene (FEP, a type of Teflon). Dramatic changes in material properties were observed when comparing areas of high solar fluence to areas of low solar fluence. Cross sectional analysis shows atomic oxygen (AO) erosion values up to 25.4 mu m (1 mil). Greater occurrences of through-thickness cracking and surface microcracking were observed in areas of high solar exposure. Atomic force microscopy (AFM) showed increases in surface microhardness measurements with increasing solar exposure. Decreases in FEP tensile strength and elongation were measured when compared to non-flight material. Erosion yield and tensile results are compared with FEP data from the Long Duration Exposure Facility. AO erosion yield data, solar fluence values, contamination, micrometeoroid or debris impact sites, and optical properties are presented.

Stress response in rat brain after different durations of noise exposure.

PubMed

Samson, James; Sheeladevi, Rathinasamy; Ravindran, Rajan; Senthilvelan, Manohar

2007-01-01

The alteration in the levels of plasma corticosterone, brain norepinephrine (NE), and expression of brain heat shock proteins (Hsp70) after different durations of noise exposure (acute, 1 day; sub-acute, 15 days; chronic, 30 days) has been studied to analyze their role in combating time-dependent stress effects of noise. Broadband white noise (100dB) exposure to male Wistar albino rats significantly increased the levels of plasma corticosterone and NE in all three durations of noise exposure. The sustained increase observed in their levels in the chronic group suggests that animals are not getting adapted to noise even after 30 days of exposure. The important role of Hsp70 in combating noise induced stress is evident from the significant increase in its expression after chronic exposure, while there was a reciprocal decrease in the NE and corticosterone when compared with their levels after acute and sub-acute noise exposure. This clearly indicates that the time-dependent stress response to noise exposure is a complex mechanism involving highly interconnected systems such as hypothalamo-pituitary-adrenal (HPA) axis, heat shock proteins and may have serious implications in vital organs, particularly in the brain when there is a prolonged noise exposure.

Ion microprobe elemental analyses of impact features on interplanetary dust experiment sensor surfaces

NASA Technical Reports Server (NTRS)

Simon, Charles G.; Hunter, Jerry L.; Wortman, Jim J.; Griffis, Dieter P.

1992-01-01

Hypervelocity impact features from very small particles (less than 3 microns in diameter) on several of the electro-active dust sensors used in the Interplanetary Dust Experiment (IDE) were subjected to elemental analysis using an ion microscope. The same analytical techniques were applied to impact and containment features on a set of ultra-pure, highly polished single crystal germanium wafer witness plates that were mounted on tray B12. Very little unambiguously identifiable impactor debris was found in the central craters or shatter zones of small impacts in this crystalline surface. The surface contamination, ubiquitous on the surface of the Long Duration Exposure Facility, has greatly complicated data collection and interpretation from microparticle impacts on all surfaces.

A pulse-forming network for particle path visualization. [at Ames Aeromechanics Water Tunnel Facility

NASA Technical Reports Server (NTRS)

Mcalister, K. W.

1981-01-01

A procedure is described for visualizing nonsteady fluid flow patterns over a wide velocity range using discrete nonluminous particles. The paramount element responsible for this capability is a pulse-forming network with variable inductance that is used to modulate the discharge of a fixed amount of electrical energy through a xenon flashtube. The selectable duration of the resultant light emission functions as a variable shutter so that particle path images of constant length can be recorded. The particles employed as flow markers are hydrogen bubbles that are generated by electrolysis in a water tunnel. Data are presented which document the characteristics of the electrical circuit and establish the relation of particle velocity to both section inductance and film exposure.

Curation of Microscopic Astromaterials by NASA: "Gathering Dust Since 1981"

NASA Technical Reports Server (NTRS)

Frank, D. R.; Bastien, R. K.; Rodriguez, M.; Gonzalez, C.; Zolensky, M. E.

2013-01-01

Employing the philosophy that "Small is Beautiful", NASA has been collecting and curating microscopic astromaterials since 1981. These active collections now include interplanetary dust collected in Earth's stratosphere by U-2, ER-2 and WB-57F aircraft (the Cosmic Dust Program - our motto is "Gathering dust since 1981"), comet Wild-2 coma dust (the Stardust Mission), modern interstellar dust (also the Stardust Mission), asteroid Itokawa regolith dust (the Hayabusa Mission - joint curation with JAXA-ISAS), and interplanetary dust impact features on recovered portions of the following spacecraft: Skylab, the Solar Maximum Satellite, the Palapa Satellite, the Long Duration Exposure Facility (LDEF), the MIR Space Station, the International Space Station, and the Hubble Space Telescope (all in the Space Exposed Hardware Laboratory).

The effect of the low Earth orbit environment on space solar cells: Results of the advanced photovoltaic experiment (S0014)

NASA Technical Reports Server (NTRS)

Brinker, David J.; Hickey, John R.

1992-01-01

The Advanced Photovoltaic Experiment (APEX), containing over 150 solar cells and sensors, was designed to generate laboratory reference standards as well as to explore the durability of a wide variety of space solar cells. Located on the leading edge of the Long Duration Exposure Facility (LDEF), APEX received the maximum possible dosage of atomic oxygen and ultraviolet radiation, as well as enormous numbers of impacts from micrometeoroids and debris. The effect of the low earth orbital (LEO) environment on the solar cells and materials of APEX will be discussed in this paper. The on-orbit performance of the solar cells, as well as a comparison of pre- and postflight laboratory performance measurements, will be presented.

Predictors of radiation exposure to providers during percutaneous nephrolithotomy

PubMed Central

Wenzler, David L.; Abbott, Joel E.; Su, Jeannie J.; Shi, William; Slater, Richard; Miller, Daniel; Siemens, Michelle J.; Sur, Roger L.

2017-01-01

Background: Limited studies have reported on radiation risks of increased ionizing radiation exposure to medical personnel in the urologic community. Fluoroscopy is readily used in many urologic surgical procedures. The aim of this study was to determine radiation exposure to all operating room personnel during percutaneous nephrolithotomy (PNL), commonly performed for large renal or complex stones. Materials and Methods: We prospectively collected personnel exposure data for all PNL cases at two academic institutions. This was collected using the Instadose™ dosimeter and reported both continuously and categorically as high and low dose using a 10 mrem dose threshold, the approximate amount of radiation received from one single chest X-ray. Predictors of increased radiation exposure were determined using multivariate analysis. Results: A total of 91 PNL cases in 66 patients were reviewed. Median surgery duration and fluoroscopy time were 142 (38–368) min and 263 (19–1809) sec, respectively. Median attending urologist, urology resident, anesthesia, and nurse radiation exposure per case was 4 (0–111), 4 (0–21), 0 (0–5), and 0 (0–5) mrem, respectively. On univariate analysis, stone area, partial or staghorn calculi, surgery duration, and fluoroscopy time were associated with high attending urologist and resident radiation exposure. Preexisting access that was utilized was negatively associated with resident radiation exposure. However, on multivariate analysis, only fluoroscopy duration remained significant for attending urologist radiation exposure. Conclusion: Increased stone burden, partial or staghorn calculi, surgery and fluoroscopy duration, and absence of preexisting access were associated with high provider radiation exposure. Radiation safety awareness is essential to minimize exposure and to protect the patient and all providers from potential radiation injury. PMID:28216931

PROGRAMMABLE EXPOSURE CONTROL SYSTEM FOR DETERMINATION OF THE EFFECTS OF POLLUTANT EXPOSURE REGIMES ON PLANT GROWTH

EPA Science Inventory

A field-exposure research facility was constructed to provide a controlled environment to determine the influence of the various components of ozone exposure on plant response. The facility uses modified open-top chambers and an automated control system for continuous delivery an...

Occupational radiation Exposure at Agreement State-Licensed Materials Facilities, 1997-2010

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

U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research

The purpose of this report is to examine occupational radiation exposures received under Agreement State licensees. As such, this report reflects the occupational radiation exposure data contained in the Radiation Exposure Information and Reporting System (REIRS) database, for 1997 through 2010, from Agreement State-licensed materials facilities.

Radiographic trends of dental offices and dental schools.

PubMed

Suleiman, O H; Spelic, D C; Conway, B; Hart, J C; Boyce, P R; Antonsen, R G

1999-07-01

A survey of private practice facilities in the United States that perform dental radiography was conducted in 1993 and repeated in dental schools in 1995-1996. Both surveys were conducted as part of the Nationwide Evaluation of X-ray Trends, or NEXT, survey program. A representative sample of dental facilities from each participating state were surveyed, and data on patient radiation exposure, radiographic technique, film-image quality, film-processing quality and darkroom fog were collected. The authors found that dental schools use E-speed film more frequently than do private practice facilities. The use of E-speed film and better film processing by dental schools resulted in lower patient radiation exposures without sacrificing image quality. The authors also found that dental school darkrooms had lower ambient fog levels than did those of private practice facilities. The distribution for the 1993 NEXT survey facilities was greater than that observed for dental schools for radiation exposure, film-processing quality and darkroom fog. Dental schools, in general, had better film quality and lower radiation exposures than did private practice facilities. Facilities need to emphasize better quality processing and the use of E-speed film to reduce patient exposure and improve image quality.

Peak expiratory flow rate in handloom weavers.

PubMed

Tiwari, R R; Zodpey, S P; Deshpande, S G; Vasudeo, N D

1998-04-01

The present cross-sectional study with a comparison group was carried out to investigate peak expiratory flow rate (PEFR) in handloom weavers and to study relationship between reduction in PEFR with age, smoking, duration of cotton dust exposure and respiratory morbidity. This study include 319 handloom weavers and equal number of individuals (group matched for age and pair matched for sex) in comparison group. The decline in PEFR was significantly associated with advancing age, longer duration of exposure to cotton dust, tobacco smoking and presence of respiratory morbidity on univariate analysis, whereas on multivariate analysis longer duration of exposure to cotton dust and tobacco smoking was found to be non significant.

Sunlight Exposure, Work Hours, Caffeine Consumption, and Sleep Duration in the Naval Environment.

PubMed

Shattuck, Nita L; Matsangas, Panagiotis

2017-06-01

Sailors in the U.S. Navy are habitual shiftworkers, often experiencing circadian misalignment due to their irregular work/rest schedules. This study assessed the effect of sunlight exposure, work hours, and caffeinated beverage consumption on the daily sleep duration of crewmembers of a U.S. Navy ship during a 2-wk underway period. Working in an artificially lit area with no access to sunlight during work hours, U.S. Navy crew members (N = 91) used daily logs to report their daily activity, caffeinated beverage consumption, and exposure to sunlight while off-duty; sleep was assessed by wrist-worn actigraphy. Hours of sunlight exposure, work duration, and the amount of coffee/tea/soft drinks were statistically significant predictors of sleep duration. On average, crewmembers who reported more than one half-hour of sunlight each day slept on average ∼40 min (10%) less than their peers working the same shifts who received less than one half-hour of sunlight (on average 6.05 ± 0.90 h vs. 6.71 ± 0.91 h, respectively). Exposure to sunlight, work hours, and consumption of caffeinated beverages are important factors when planning watchstanding schedules at sea. Even though further research is needed, our results suggest that even brief exposure to sunlight may contribute to circadian misalignment that negatively affects sleep in the operational environment. Educating crewmembers about sleep hygiene, especially the important roles played by sunlight and caffeine, could potentially improve the sleep and fatigue levels of this population of maritime shiftworkers.Shattuck NL, Matsangas P. Sunlight exposure, work hours, caffeine consumption, and sleep duration in the naval environment. Aerosp Med Hum Perform. 2017; 88(6):579-585.

Personalized technologist dose audit feedback for reducing patient radiation exposure from CT.

PubMed

Miglioretti, Diana L; Zhang, Yue; Johnson, Eric; Lee, Choonsik; Morin, Richard L; Vanneman, Nicholas; Smith-Bindman, Rebecca

2014-03-01

The aim of this study was to determine whether providing radiologic technologists with audit feedback on doses from CT examinations they conduct and education on dose-reduction strategies reduces patients' radiation exposure. This prospective, controlled pilot study was conducted within an integrated health care system from November 2010 to October 2011. Ten technologists at 2 facilities received personalized dose audit reports and education on dose-reduction strategies; 9 technologists at a control facility received no intervention. Radiation exposure was measured by the dose-length product (DLP) from CT scans performed before (n = 1,630) and after (n = 1,499) the intervention and compared using quantile regression. Technologists were surveyed before and after the intervention. For abdominal CT, DLPs decreased by 3% to 12% at intervention facilities but not at the control facility. For brain CT, DLPs significantly decreased by 7% to 12% at one intervention facility; did not change at the second intervention facility, which had the lowest preintervention DLPs; and increased at the control facility. Technologists were more likely to report always thinking about radiation exposure and associated cancer risk and optimizing settings to reduce exposure after the intervention. Personalized audit feedback and education can change technologists' attitudes about, and awareness of, radiation and can lower patient radiation exposure from CT imaging. Copyright © 2014 American College of Radiology. All rights reserved.

EXPOSE-R2: The Astrobiological ESA Mission on Board of the International Space Station.

PubMed

Rabbow, Elke; Rettberg, Petra; Parpart, Andre; Panitz, Corinna; Schulte, Wolfgang; Molter, Ferdinand; Jaramillo, Esther; Demets, René; Weiß, Peter; Willnecker, Rainer

2017-01-01

On July 23, 2014, the Progress cargo spacecraft 56P was launched from Baikonur to the International Space Station (ISS), carrying EXPOSE-R2, the third ESA (European Space Agency) EXPOSE facility, the second EXPOSE on the outside platform of the Russian Zvezda module, with four international astrobiological experiments into space. More than 600 biological samples of archaea, bacteria (as biofilms and in planktonic form), lichens, fungi, plant seeds, triops eggs, mosses and 150 samples of organic compounds were exposed to the harsh space environment and to parameters similar to those on the Mars surface. Radiation dosimeters distributed over the whole facility complemented the scientific payload. Three extravehicular activities later the chemical samples were returned to Earth on March 2, 2016, with Soyuz 44S, having spent 588 days in space. The biological samples arrived back later, on June 18, 2016, with 45S, after a total duration in space of 531 days. The exposure of the samples to Low Earth Orbit vacuum lasted for 531 days and was divided in two parts: protected against solar irradiation during the first 62 days, followed by exposure to solar radiation during the subsequent 469 days. In parallel to the space mission, a Mission Ground Reference (MGR) experiment with a flight identical Hardware and a complete flight identical set of samples was performed at the premises of DLR (German Aerospace Center) in Cologne by MUSC (Microgravity User Support Center), according to the mission data either downloaded from the ISS (temperature data, facility status, inner pressure status) or provided by RedShift Design and Engineering BVBA, Belgium (calculated ultra violet radiation fluence data). In this paper, the EXPOSE-R2 facility, the experimental samples, mission parameters, environmental parameters, and the overall mission and MGR sequences are described, building the background for the research papers of the individual experiments, their analysis and results.

EXPOSE-R2: The Astrobiological ESA Mission on Board of the International Space Station

PubMed Central

Rabbow, Elke; Rettberg, Petra; Parpart, Andre; Panitz, Corinna; Schulte, Wolfgang; Molter, Ferdinand; Jaramillo, Esther; Demets, René; Weiß, Peter; Willnecker, Rainer

2017-01-01

On July 23, 2014, the Progress cargo spacecraft 56P was launched from Baikonur to the International Space Station (ISS), carrying EXPOSE-R2, the third ESA (European Space Agency) EXPOSE facility, the second EXPOSE on the outside platform of the Russian Zvezda module, with four international astrobiological experiments into space. More than 600 biological samples of archaea, bacteria (as biofilms and in planktonic form), lichens, fungi, plant seeds, triops eggs, mosses and 150 samples of organic compounds were exposed to the harsh space environment and to parameters similar to those on the Mars surface. Radiation dosimeters distributed over the whole facility complemented the scientific payload. Three extravehicular activities later the chemical samples were returned to Earth on March 2, 2016, with Soyuz 44S, having spent 588 days in space. The biological samples arrived back later, on June 18, 2016, with 45S, after a total duration in space of 531 days. The exposure of the samples to Low Earth Orbit vacuum lasted for 531 days and was divided in two parts: protected against solar irradiation during the first 62 days, followed by exposure to solar radiation during the subsequent 469 days. In parallel to the space mission, a Mission Ground Reference (MGR) experiment with a flight identical Hardware and a complete flight identical set of samples was performed at the premises of DLR (German Aerospace Center) in Cologne by MUSC (Microgravity User Support Center), according to the mission data either downloaded from the ISS (temperature data, facility status, inner pressure status) or provided by RedShift Design and Engineering BVBA, Belgium (calculated ultra violet radiation fluence data). In this paper, the EXPOSE-R2 facility, the experimental samples, mission parameters, environmental parameters, and the overall mission and MGR sequences are described, building the background for the research papers of the individual experiments, their analysis and results. PMID:28861052

Health care delivery system for long duration manned space operations

NASA Technical Reports Server (NTRS)

Logan, J. S.; Shulman, E. L.; Johnson, P. C.

1983-01-01

Specific requirements for medical support of a long-duration manned facility in a low earth orbit derive from inflight medical experience, projected medical scenarios, mission related spacecraft and environmental hazards, health maintenance, and preventive medicine. A sequential buildup of medical capabilities tailored to increasing mission complexity is proposed. The space station health maintenance facility must provide preventive, diagnostic, and therapeutic medical support as immediate rescue capability may not exist.

Application of physiologically based pharmacokinetic (PBPK) model of trichloroethylene in rats for estimation of internal dose

EPA Science Inventory

Potential human health risk from chemical exposure must often be assessed for conditions for which suitable human or animal data are not available, requiring extrapolation across duration and concentration. The default method for exposure-duration adjustment is based on Haber's r...

Mars Radiation Risk Assessment and Shielding Design for Long-term Exposure to Ionizing Space Radiation

NASA Technical Reports Server (NTRS)

Tripathi, Ram K.; Nealy, John E.

2007-01-01

NASA is now focused on the agency's vision for space exploration encompassing a broad range of human and robotic missions including missions to Moon, Mars and beyond. As a result, there is a focus on long duration space missions. NASA is committed to the safety of the missions and the crew, and there is an overwhelming emphasis on the reliability issues for space missions and the habitat. The cost-effective design of the spacecraft demands a very stringent requirement on the optimization process. Exposure from the hazards of severe space radiation in deep space and/or long duration missions is a critical design constraint and a potential 'show stopper'. Thus, protection from the hazards of severe space radiation is of paramount importance to the agency's vision. It is envisioned to have long duration human presence on the Moon for deep space exploration. The exposures from ionizing radiation - galactic cosmic radiation and solar particle events - and optimized shield design for a swing-by and a long duration Mars mission have been investigated. It is found that the technology of today is inadequate for safe human missions to Mars, and revolutionary technologies need to be developed for long duration and/or deep space missions. The study will provide a guideline for radiation exposure and protection for long duration missions and career astronauts and their safety.

Characterization of exposure to silver nanoparticles in a manufacturing facility

NASA Astrophysics Data System (ADS)

Park, Junsu; Kwak, Byoung Kyu; Bae, Eunjoo; Lee, Jeongjin; Kim, Younghun; Choi, Kyunghee; Yi, Jongheop

2009-10-01

An assessment of the extent of exposure to nanomaterials in the workplace will be helpful in improving the occupational safety of workers. It is essential that the exposure data in the workplace are concerned with risk management to evaluate and reduce worker exposure. In a manufacturing facility dealing with nanomaterials, some exposure data for gas-phase reactions are available, but much less information is available regarding liquid-phase reactions. Although the potential for inhaling nanomaterials in a liquid-phase process is less than that for gas-phase, the risks of exposure during wet-chemistry processes are not negligible. In this study, we monitored and analyzed the exposure characteristics of silver nanoparticles during a liquid-phase process in a commercial production facility. Based on the measured exposure data, the source of Ag nanoparticles emitted during the production processes was indentified and a mechanism for the growth of Ag nanoparticle released is proposed. The data reported in this study could be used to establish occupational safety guidelines in the nanotechnology workplace, especially in a liquid-phase production facility.

Duration as a measure of the spiral aftereffect.

DOT National Transportation Integrated Search

1963-01-01

Describes an experiment that studied the reliability of duration as a measure of the spiral aftereffect. The results for 10 Ss indicate that duration is a highly reliable measure and that duration is a simple monotonic function of exposure-time.

An analysis of workplace exposures to benzene over four decades at a petrochemical processing and manufacturing facility (1962-1999).

PubMed

Sahmel, J; Devlin, K; Burns, A; Ferracini, T; Ground, M; Paustenbach, D

2013-01-01

Benzene, a known carcinogen, can be generated as a by-product during the use of petroleum-based raw materials in chemical manufacturing. The aim of this study was to analyze a large data set of benzene air concentration measurements collected over nearly 40 years during routine employee exposure monitoring at a petrochemical manufacturing facility. The facility used ethane, propane, and natural gas as raw materials in the production of common commercial materials such as polyethylene, polypropylene, waxes, adhesives, alcohols, and aldehydes. In total, 3607 benzene air samples were collected at the facility from 1962 to 1999. Of these, in total 2359 long-term (>1 h) personal exposure samples for benzene were collected during routine operations at the facility between 1974 and 1999. These samples were analyzed by division, department, and job title to establish employee benzene exposures in different areas of the facility over time. Sampling data were also analyzed by key events over time, including changes in the occupational exposure limits (OELs) for benzene and key equipment process changes at the facility. Although mean benzene concentrations varied according to operation, in nearly all cases measured benzene quantities were below the OEL in place at the time for benzene (10 ppm for 1974-1986 and 1 ppm for 1987-1999). Decreases in mean benzene air concentrations were also found when data were evaluated according to 7- to 10-yr periods following key equipment process changes. Further, an evaluation of mortality rates for a retrospective employee cohort (n = 3938) demonstrated that the average personal benzene exposures at this facility (0.89 ppm for the period 1974-1986 and 0.125 ppm for the period 1987-1999) did not result in increased standardized mortality ratio (SMRs) for diseases or malignancies of the lymphatic system. The robust nature of this data set provides comprehensive exposure information that may be useful for assessing human benzene exposures at similar facilities. The data also provide a basis for comparable measured exposure levels and the potential for adverse health effects. These data may also prove beneficial for comparing relative exposure potential for production versus nonproduction operations and the relationship between area and personal breathing zone samples.

Translation of Toxicity Data into CW Agent Toxicity Estimates

DTIC Science & Technology

2003-07-01

UNLIMITED UNCLASSIFIED/UNLIMITEDPrepared by Douglas R. Sommerville, PE US Army ECBC, APG, MD Dependence of Toxic Effect on Exposure Time Inhalation (IH...to longer exposure durations. Toxicity estimates for exposure durations ranging from 2 to 360 minutes have been derived for six agents (GA, GB, GD...individuals having effects greater in severity than the defining effect of the ECTYY Cn T = k Toxic load equation 5 6 Edgewood Chemical Biological Center

The confidence-accuracy relationship for eyewitness identification decisions: Effects of exposure duration, retention interval, and divided attention.

PubMed

Palmer, Matthew A; Brewer, Neil; Weber, Nathan; Nagesh, Ambika

2013-03-01

Prior research points to a meaningful confidence-accuracy (CA) relationship for positive identification decisions. However, there are theoretical grounds for expecting that different aspects of the CA relationship (calibration, resolution, and over/underconfidence) might be undermined in some circumstances. This research investigated whether the CA relationship for eyewitness identification decisions is affected by three, forensically relevant variables: exposure duration, retention interval, and divided attention at encoding. In Study 1 (N = 986), a field experiment, we examined the effects of exposure duration (5 s vs. 90 s) and retention interval (immediate testing vs. a 1-week delay) on the CA relationship. In Study 2 (N = 502), we examined the effects of attention during encoding on the CA relationship by reanalyzing data from a laboratory experiment in which participants viewed a stimulus video under full or divided attention conditions and then attempted to identify two targets from separate lineups. Across both studies, all three manipulations affected identification accuracy. The central analyses concerned the CA relation for positive identification decisions. For the manipulations of exposure duration and retention interval, overconfidence was greater in the more difficult conditions (shorter exposure; delayed testing) than the easier conditions. Only the exposure duration manipulation influenced resolution (which was better for 5 s than 90 s), and only the retention interval manipulation affected calibration (which was better for immediate testing than delayed testing). In all experimental conditions, accuracy and diagnosticity increased with confidence, particularly at the upper end of the confidence scale. Implications for theory and forensic settings are discussed.

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

Paul, I.R.

A pilot study in two states led to the establishment of the Dental Exposure Normalization Technique (DENT) program. This, in brief, is an exposure reduction and quality assurance program for radiological health agencies. The health agency sends X-ray exposure cards to dental X-ray facilities. These are exposed by the dentist and returned for analysis. Facilities which show excessive exposure are then visited to demonstrate the changes in exposure and processing necessary to produce diagnostic quality radiographs with minimum patient exposure.

Simulation of the synergistic low Earth orbit effects of vacuum thermal cycling, vacuum UV radiation, and atomic oxygen

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Degroh, Kim K.; Stidham, Curtis R.; Stueber, Thomas J.; Dever, Therese M.; Rodriguez, Elvin; Terlep, Judith A.

1992-01-01

In order to assess the low Earth orbit (LEO) durability of candidate space materials, it is necessary to use ground laboratory facilities which provide LEO environmental effects. A facility combining vacuum thermal cycling and vacuum ultraviolet (VUV) radiation has been designed and constructed at NASA Lewis Research Center for this purpose. This facility can also be operated without the VUV lamps. An additional facility can be used to provide VUV exposure only. By utilizing these facilities, followed by atomic oxygen exposure in an RF plasma asher, the effects of the individual vacuum thermal cycling and VUV environments can be compared to the effect of the combined vacuum thermal cycling/VUV environment on the atomic oxygen durability of materials. The synergistic effects of simulated LEO environmental conditions on materials were evaluated by first exposing materials to vacuum thermal cycling, VUV, and vacuum thermal cycling/VUV environments followed by exposure to atomic oxygen in an RP plasma asher. Candidate space power materials such as atomic oxygen protected polyimides and solar concentrator mirrors were evaluated using these facilities. Characteristics of the Vacuum Thermal Cycling/VUV Exposure Facility which simulates the temperature sequences and solar ultraviolet radiation exposure that would be experienced by a spacecraft surface in LEO are discussed. Results of durability evaluations of some candidate space power materials to the simulated LEO environmental conditions will also be discussed. Such results have indicated that for some materials, atomic oxygen durability is affected by previous exposure to thermal cycling and/or VUV exposure.

Simulated Space Environment Effects on the Blocking Force of Silicone Adhesive

NASA Technical Reports Server (NTRS)

Boeder, Paul; Mikatarian, Ron; Koontz, Steve; Albyn, Keith; Finckenor, Miria

2005-01-01

The International Space Station (ISS) solar arrays utilize MD-944 diode tape to protect the underlying diodes in the solar array panel circuit and also provide thermal conditioning and mechanical support. The diode tape consists of silicone pressure sensitive adhesive (Dow Coming QC-7725) with a protective Kapton over-layer. On-orbit, the Kapton over-layer will erode under exposure to atomic oxygen (AO) and the underlying exposed silicone adhesive will ultimately convert, under additional AO exposure, to a glass like silicate. The current operational plan is to retract ISS solar array P6 and leave it stored under load for a long duration (6 months or more) during ISS assembly. With the Kapton over-layer eroded away, the exposed silicone adhesive must not cause the solar array to stick to itself or cause the solar array to fail during redeployment. Previous testing by Lockheed-Martin Space Systems (LMSS) characterized silicone blocking following exposure to low energy atomic oxygen (AO) in an asher facility, but this is believed to be conservative. An additional series of tests was performed by the Environmental Effects Group at MSFC under direction from the ISS Program Office Environments Team. This test series included high energy AO (5 eV), near ultraviolet (NUV) radiation and ionizing radiation, singly and in combination. Additional samples were exposed to thermal energy AO (<0.1 ev) for comparison to the LMSS tests. Diode tape samples were exposed to each environment constituent individually, put under preload for seven days and then the resulting blocking force was measured using a tensile machine. Additional samples were exposed to AO, NUV and electrons in series and then put under long term (three to ten months) preload to determine the effect of preload duration on the resulting blocking force of the silicone-to-silicone bond. Test results indicate that high energy AO, ultraviolet radiation and electron ionizing radiation exposure all reduce the blocking force for a silicone-to-silicone bond. AO exposure produces the most significant reduction in blocking force.

Airways obstruction among older construction and trade workers at Department of Energy nuclear sites.

PubMed

Dement, John M; Welch, Laura; Ringen, Knut; Bingham, Eula; Quinn, Patricia

2010-03-01

A study of chronic obstructive pulmonary disease (COPD) among 7,579 current and former workers participating in medical screening programs at Department of Energy (DOE) nuclear weapons facilities through September 2008 was undertaken. Participants provided a detailed work and exposure history and underwent a respiratory examination that included a respiratory history, respiratory symptoms, a posterior-anterior (P-A) chest radiograph classified by International Labour Office (ILO) criteria, and spirometry. Statistical models were developed to generate group-level exposure estimates that were used in multivariate logistic regression analyses to explore the risk of COPD in relation to exposures to asbestos, silica, cement dust, welding, paints, solvents, and dusts/fumes from paint removal. Risk for COPD in the study population was compared to risk for COPD in the general US population as determined in National Health and Nutrition Examination Survey (NHANES III). The age-standardized prevalence ratio of COPD among DOE workers compared to all NHANES III data was 1.3. Internal analyses found the odds ratio of COPD to range from 1.6 to 3.1 by trade after adjustment for age, race, sex, smoking, and duration of DOE employment. Statistically significant associations were observed for COPD and exposures to asbestos, silica, welding, cement dusts, and some tasks associated with exposures to paints, solvents, and removal of paints. Our study of construction workers employed at DOE sites demonstrated increased COPD risk due to occupational exposures and was able to identify specific exposures increasing risk. This study provides additional support for prevention of both smoking and occupational exposures to reduce the burden of COPD among construction workers. 2009 Wiley-Liss, Inc.

What is the role of tobacco control advertising intensity and duration in reducing adolescent smoking prevalence? Findings from 16 years of tobacco control mass media advertising in Australia.

PubMed

White, Victoria M; Durkin, Sarah J; Coomber, Kerri; Wakefield, Melanie A

2015-03-01

To examine how the intensity and duration of tobacco control advertising relate to adolescent smoking prevalence. Australian students (aged 12-17 years) participating in a national survey conducted triennially between 1993 and 2008 (sample size range 12 314-16 611). The outcome measure was students' smoking in the previous 4 weeks collected through anonymous, self-completed surveys. For each student, monthly targeted rating points (TRPs, a measure of television advertising exposure) for tobacco control advertising was calculated for the 3 and 12 months prior to surveying. For each time period, cumulative TRPs exposure and exposure to three intensity levels (≥100 TRPs/month; ≥400 TRPs/month; ≥800 TRPs/month) over increasing durations (eg, 1 month, 2 months, etc) were calculated. Logistic regression examined associations between TRPs and adolescent smoking after controlling for demographic and policy variables. Past 3-month cumulative TRPs were found to have an inverse relationship with smoking prevalence. Low TRPs exposure in the past 12 months was positively associated with adolescent smoking prevalence. However, smoking prevalence reduced with cumulative exposure levels above 5800 cumulative TRPs. Additionally, exposure to ≥400 TRPs/month and ≥800 TRPs/month were associated with reduced likelihood of smoking, although the duration needed for this effect differed for the two intensity levels. When intensity was ≥400 TRPs/month, the odds of smoking only reduced with continuous exposure. When intensity was ≥800 TRPs/month, exposure at levels less than monthly was associated with reductions in smoking prevalence. Both antismoking advertising intensity and duration are important for ensuring reductions in adolescent smoking prevalence. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Retrospective assessment of solvent exposure in paint manufacturing.

PubMed Central

Glass, D C; Spurgeon, A; Calvert, I A; Clark, J L; Harrington, J M

1994-01-01

This paper describes how exposure to solvents at two large paint making sites was assessed in a study carried out to investigate the possibility of neuropsychological effects resulting from long term exposure to organic solvents. A job exposure matrix was constructed by buildings and year. A detailed plant history was taken and this was used to identify uniform exposure periods during which workers' exposure to solvents was not thought to have changed significantly. Exposure monitoring data, collected by the company before the study, was then used to characterise exposure within each uniform exposure period. Estimates were made for periods during which no air monitoring was available. Individual detailed job histories were collected for subjects and controls. The job histories were used to estimate exposure on an individual basis with the job exposure matrix. Exposure was expressed as duration, cumulative dose, and intensity of exposure. Classification of exposure by duration alone was found to result in misclassification of subjects. PMID:7951794

Sunscreen use and intentional exposure to ultraviolet A and B radiation: a double blind randomized trial using personal dosimeters

PubMed Central

Autier, P; Doré, J-F; Reis, A C; Grivegnée, A; Ollivaud, L; Truchetet, F; Chamoun, E; Rotmensz, N; Severi, G; Césarini, J-P

2000-01-01

A previous randomized trial found that sunscreen use could extend intentional sun exposure, thereby possibly increasing the risk of cutaneous melanoma. In a similarly designed trial, we examined the effect of the use of sunscreens having different sun protection factor (SPF) on actual exposure to ultraviolet B (UVB) and ultraviolet A (UVA) radiation. In June 1998, 58 European participants 18–24 years old were randomized to receive a SPF 10 or 30 sunscreens and were asked to complete daily records of their sun exposure during their summer holidays of whom 44 utilized a personal UVA and UVB dosimeter in a standard way during their sunbathing sessions. The median daily sunbathing duration was 2.4 hours in the SPF 10 group and 3.0 hours in the SPF 30 group (P = 0.054). The increase in daily sunbathing duration was paralleled by an increase in daily UVB exposure, but not by changes in UVA or UVB accumulated over all sunbathing sessions, or in daily UVA exposure. Of all participants, those who used the SPF 30 sunscreen and had no sunburn spent the highest number of hours in sunbathing activities. Differences between the two SPF groups in total number of sunbathing hours, daily sunbathing duration, and daily UVB exposure were largest among participants without sunburn during holidays. Among those with sunburn, the differences between the two groups tended to reduce. In conclusion, sunscreens used during sunbathing tended to increase the duration of exposures to doses of ultraviolet radiation below the sunburn threshold. © 2000 Cancer Research Campaign PMID:11027441

Duration of Exposure and the Dose-Response Model of PTSD

ERIC Educational Resources Information Center

Kaysen, Debra; Rosen, Gerald; Bowman, Marilyn; Resick, Patricia A.

2010-01-01

A dose-response model underlies posttraumatic stress disorder (PTSD) and posits a relationship between event magnitude and clinical outcome. The present study examines whether one index of event magnitude--duration of exposure--contributes to risk of PTSD among female victims of sexual assault. Findings support a small but significant contribution…

The effect of theobromine 200 mg/l topical gel exposure duration against surface enamel hardness resistance from 1% citric acid

NASA Astrophysics Data System (ADS)

Herisa, H. M.; Noerdin, A.; Eriwati, Y. K.

2017-08-01

Theobromine can be used to prevent the demineralization of enamel and can stimulate the growth of new enamels. This study analyzes the effect of theobromine’s gel duration exposure on enamel hardness resistance from 1% citric acid. Twenty-eight specimens were divided into three experimental groups; were exposed to theobromine gel 200 mg/l for 16, 48, and 96 minutes; and were then immersed in 1% citric acid. The control group was only immersed in 1% citric acid. Results: A Wilcoxon test showed a significant increase and decrease in enamel microhardness after exposure to theobromine gel and citric acid (p < 0.05). A Mann-Whitney test showed a significant increase and decrease in enamel microhardness between different durations of exposure to theobromine gel and immersion in citric acid (p < 0.05). The application of theobromine gel 200mg/L increased enamel microhardness but did not contribute to the enamel’s hardness resistance after immersion in 1% citric acid. The duration of theobromine gel application affected enamel microhardness and acid resistance.

Issues on human acceleration tolerance after long-duration space flights

NASA Technical Reports Server (NTRS)

Kumar, K. Vasantha; Norfleet, William T.

1992-01-01

This report reviewed the literature on human tolerance to acceleration at 1 G and changes in tolerance after exposure to hypogravic fields. It was found that human tolerance decreased after exposure to hypokinetic and hypogravic fields, but the magnitude of such reduction ranged from 0 to 30 percent for plateau G forces and 30 to 70 percent for time tolerance on sustained G forces. A logistic regression model of the probability of individuals with 25 percent reduction in +Gz tolerance after 1 to 41 days of hypogravic exposures was constructed. The estimated values from the model showed a good correlation with the observed data. A brief review of the need for in-flight centrifuge during long-duration missions was also presented. Review of the available data showed that the use of countermeasures (such as anti-G suits, periodic acceleration, and exercise) reduced the decrement in acceleration tolerance after long-duration space flights. Areas of further research include quantification of the effect of countermeasures on tolerance, and methods to augment tolerance during and after exposures to hypogravic fields. Such data are essential for planning long-duration human missions.

The Cumulative Lifting Index (CULI) for the Revised NIOSH Lifting Equation: Quantifying Risk for Workers With Job Rotation.

PubMed

Garg, Arun; Kapellusch, Jay M

2016-08-01

The objectives were to: (a) develop a continuous frequency multiplier (FM) for the Revised NIOSH Lifting Equation (RNLE) as a function of lifting frequency and duration of a lifting task, and (b) describe the Cumulative Lifting Index (CULI), a methodology for estimating physical exposure to workers with job rotation. The existing FM for the RNLE (FME) does not differentiate between task duration >2 hr and <8 hr, which makes quantifying physical exposure to workers with job rotation difficult and presents challenges to job designers. Using the existing FMs for 1, 2, and 8 hr of task durations, we developed a continuous FM (FMP) that extends to 12 hr per day. We simulated 157,500 jobs consisting of two tasks each and, using different combinations of Frequency Independent Lifting Index, lifting frequency and duration of lifting. Biomechanical stresses were estimated using the CULI, time-weighted average (TWA), and peak exposure. The median difference between FME and FMP was ±1% (range: 0%-15%). Compared to CULI, TWA underestimated risk of low-back pain (LBP) for 18% to 30% of jobs, and peak exposure for an assumed 8-hr work shift overestimated risk of LBP for 20% to 25% of jobs. Peak task exposure showed 90% agreement with CULI but ignored one of two tasks. The CULI partially addressed the underestimation of physical exposure using the TWA approach and overestimation of exposure using the peak-exposure approach. The proposed FM and CULI may provide more accurate physical exposure estimates, and therefore estimated risk of LBP, for workers with job rotation. © 2016, Human Factors and Ergonomics Society.

Cancer risks near nuclear facilities: the importance of research design and explicit study hypotheses.

PubMed

Wing, Steve; Richardson, David B; Hoffmann, Wolfgang

2011-04-01

In April 2010, the U.S. Nuclear Regulatory Commission asked the National Academy of Sciences to update a 1990 study of cancer risks near nuclear facilities. Prior research on this topic has suffered from problems in hypothesis formulation and research design. We review epidemiologic principles used in studies of generic exposure-response associations and in studies of specific sources of exposure. We then describe logical problems with assumptions, formation of testable hypotheses, and interpretation of evidence in previous research on cancer risks near nuclear facilities. Advancement of knowledge about cancer risks near nuclear facilities depends on testing specific hypotheses grounded in physical and biological mechanisms of exposure and susceptibility while considering sample size and ability to adequately quantify exposure, ascertain cancer cases, and evaluate plausible confounders. Next steps in advancing knowledge about cancer risks near nuclear facilities require studies of childhood cancer incidence, focus on in utero and early childhood exposures, use of specific geographic information, and consideration of pathways for transport and uptake of radionuclides. Studies of cancer mortality among adults, cancers with long latencies, large geographic zones, and populations that reside at large distances from nuclear facilities are better suited for public relations than for scientific purposes.

Enhanced cytotoxic effect of cisplatin using diagnostic ultrasound and microbubbles in vitro

NASA Astrophysics Data System (ADS)

Sasaki, Noboru; Nakamura, Kensuke; Murakami, Masahiro; Lim, Sue Yee; Ohta, Hiroshi; Yamasaki, Masahiro; Takiguchi, Mitsuyoshi

2012-10-01

Diagnostic ultrasound has accomplished drug and gene delivery by ultrasound targeted microbubble destruction (UTMD). However, the efficacy of delivery is still relatively low. Therefore, we optimized conditions of UTMD using diagnostic ultrasound and ultrasound contrast agent microbubbles. Canine thyroid adenocarcinoma cells were cultured in a 96-well plate. After addition of cisplatin and Sonazoid®, the plate was inverted to raise microbubbles near cells and incubated. Cells were exposed to diagnostic ultrasound using a linear probe operated in the contrast harmonic imaging mode. The center frequency was 2.5 MHz with a mechanical index of 1.33 and a frame rate of 48 frames/sec. Cytotoxic effect of cisplatin was evaluated 24h after exposure using trypan blue dye exclusion test. We optimized incubation duration, cisplatin concentration, and the relationship between microbubble concentration and exposure duration. The optimum enhancement was observed at incubation duration of 5min, cisplatin concentration of 1 μg/ml, and microbubble concentration of 2.4 × 105 microbubbles/ml. Exposure duration did not influence the enhancement at the microbubble concentration of 2.4 × 105 microbubbles/ml. Our results suggest that relative low concentrations of drug and microbubbles with short exposure duration might be sufficient for drug delivery by UTMD using diagnostic ultrasound.

10 CFR 451.6 - Duration of incentive payments.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 3 2014-01-01 2014-01-01 false Duration of incentive payments. 451.6 Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration of incentive... part with respect to a qualified renewable energy facility for 10 consecutive fiscal years. Such period...

10 CFR 451.6 - Duration of incentive payments.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Duration of incentive payments. 451.6 Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration of incentive... part with respect to a qualified renewable energy facility for 10 consecutive fiscal years. Such period...

10 CFR 451.6 - Duration of incentive payments.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 3 2012-01-01 2012-01-01 false Duration of incentive payments. 451.6 Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration of incentive... part with respect to a qualified renewable energy facility for 10 consecutive fiscal years. Such period...

10 CFR 451.6 - Duration of incentive payments.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 3 2011-01-01 2011-01-01 false Duration of incentive payments. 451.6 Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration of incentive... part with respect to a qualified renewable energy facility for 10 consecutive fiscal years. Such period...

10 CFR 451.6 - Duration of incentive payments.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 3 2013-01-01 2013-01-01 false Duration of incentive payments. 451.6 Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration of incentive... part with respect to a qualified renewable energy facility for 10 consecutive fiscal years. Such period...

Cohort mortality study of garment industry workers exposed to formaldehyde: update and internal comparisons.

PubMed

Meyers, Alysha R; Pinkerton, Lynne E; Hein, Misty J

2013-09-01

To further evaluate the association between formaldehyde and leukemia, we extended follow-up through 2008 for a cohort mortality study of 11,043 US formaldehyde-exposed garment workers. We computed standardized mortality ratios and standardized rate ratios stratified by year of first exposure, exposure duration, and time since first exposure. Associations between exposure duration and rates of leukemia and myeloid leukemia were further examined using Poisson regression models. Compared to the US population, myeloid leukemia mortality was elevated but overall leukemia mortality was not. In internal analyses, overall leukemia mortality increased with increasing exposure duration and this trend was statistically significant. We continue to see limited evidence of an association between formaldehyde and leukemia. However, the extended follow-up did not strengthen previously observed associations. In addition to continued epidemiologic research, we recommend further research to evaluate the biological plausibility of a causal relation between formaldehyde and leukemia. Copyright © 2013 Wiley Periodicals, Inc.

Impact on the deuterium retention of simultaneous exposure of tungsten to a steady state plasma and transient heat cycling loads

NASA Astrophysics Data System (ADS)

Huber, A.; Sergienko, G.; Wirtz, M.; Steudel, I.; Arakcheev, A.; Brezinsek, S.; Burdakov, A.; Dittmar, T.; Esser, H. G.; Kreter, A.; Linke, J.; Linsmeier, Ch; Mertens, Ph; Möller, S.; Philipps, V.; Pintsuk, G.; Reinhart, M.; Schweer, B.; Shoshin, A.; Terra, A.; Unterberg, B.

2016-02-01

The impact on the deuterium retention of simultaneous exposure of tungsten to a steady-state plasma and transient cyclic heat loads has been studied in the linear PSI-2 facility with the main objective of qualifying tungsten (W) as plasma-facing material. The transient heat loads were applied by a high-energy laser, a Nd:YAG laser (λ = 1064 nm) with an energy per pulse of up to 32 J and a duration of 1 ms. A pronounced increase in the D retention by a factor of 13 has been observed during the simultaneous transient heat loads and plasma exposure. These data indicate that the hydrogen clustering is enhanced by the thermal shock exposures, as seen on the increased blister size due to mobilization and thermal production of defects during transients. In addition, the significant increase of the D retention during the simultaneous loads could be explained by an increased diffusion of D atoms into the W material due to strong temperature gradients during the laser pulse exposure and to an increased mobility of D atoms along the shock-induced cracks. Only 24% of the retained deuterium is located inside the near-surface layer (d<4 μm). Enhanced blister formation has been observed under combined loading conditions at power densities close to the threshold for damaging. Blisters are not mainly responsible for the pronounced increase of the D retention.

Exposure of LDEF materials to atomic oxygen: Results of EOIM 3

NASA Technical Reports Server (NTRS)

Jaggers, C. H.; Meshishnek, M. J.

1995-01-01

The third Effects of Oxygen Atom Interaction with Materials (EOIM 3) experiment flew on STS-46 from July 31 to August 8, 1992. The EOIM-3 sample tray was exposed to the low-earth orbit space environment for 58.55 hours at an altitude of 124 nautical miles resulting in a calculated total atomic oxygen (AO) fluence of 1.99 x 10(exp 20) atoms/sq cm. Five samples previously flown on the Long Duration Exposure Facility (LDEF) Experiment M0003 were included on the Aerospace EOIM 3 experimental tray: (1) Chemglaze A276 white thermal control paint from the LDEF trailing edge (TE); (2) S13GLO white thermal control paint from the LDEF TE; (3) S13GLO from the LDEF leading edge (LE) with a visible contamination layer from the LDEF mission; (4) Z306 black thermal control paint from the LDEF TE with a contamination layer from the LDEF mission; and (5) anodized aluminum from the LDEF TE with a contamination layer from the LDEF mission. The purpose of this experiment was twofold: (l) investigate the response of trailing edge LDEF materials to atomic oxygen exposure, thereby simulating LDEF leading edge phenomena; (2) investigate the response of contaminated LDEF samples to atomic oxygen in attempts to understand LDEF contamination-atomic oxygen interactions. This paper describes the response of these materials to atomic oxygen exposure, and compares the results of the EOIM 3 experiment to the LDEF mission and to ground-based atomic oxygen exposure studies.

Relationship of hemoglobin to occupational exposure to motor vehicle exhaust.

PubMed

Potula, V; Hu, H

1996-01-01

To study the relationship of hemoglobin to exposure to motor vehicle exhaust. Survey. Traffic police, bus drivers, and auto-shop workers (all exposed to auto exhaust in Madras, India) and unexposed office workers. We measured levels of blood lead (by graphite furnace atomic absorption spectrophotometry), and hemoglobin. Information also was collected on age, employment duration, smoking status, alcohol ingestion, and diet type (vegetarian or nonvegetarian). Increasing exposure to motor vehicle exhaust, as reflected by job category, was significantly associated with lower levels of hemoglobin (p < 0.01). A final multivariate regression model was constructed that began with indicator variables for each job (with office workers as the reference category) and included age, duration of employment, blood lead level, alcohol ingestion, dietary type, and smoking status. After a backward-elimination procedure, employment duration as an auto-shop worker or bus driver remained as significant correlates of lower hemoglobin level and current smoking and long employment duration as significant correlates of higher hemoglobin level. Occupational exposure to automobile exhaust may be a risk factor for decreased hemoglobin level in Madras. This effect appears to be independent of blood lead level and may represent hematopoietic suppression incurred by benzene or accumulated lead burden (which is not well reflected by blood lead levels). Smoking probably increased hemoglobin level through the chronic effects of exposure to carbon monoxide. In this study, a long employment duration may have served as a proxy for better socioeconomic, and therefore, better nutritional status.

Opposite Influence of Perceptual Memory on Initial and Prolonged Perception of Sensory Ambiguity

PubMed Central

de Jong, Maartje Cathelijne; Knapen, Tomas; van Ee, Raymond

2012-01-01

Observers continually make unconscious inferences about the state of the world based on ambiguous sensory information. This process of perceptual decision-making may be optimized by learning from experience. We investigated the influence of previous perceptual experience on the interpretation of ambiguous visual information. Observers were pre-exposed to a perceptually stabilized sequence of an ambiguous structure-from-motion stimulus by means of intermittent presentation. At the subsequent re-appearance of the same ambiguous stimulus perception was initially biased toward the previously stabilized perceptual interpretation. However, prolonged viewing revealed a bias toward the alternative perceptual interpretation. The prevalence of the alternative percept during ongoing viewing was largely due to increased durations of this percept, as there was no reliable decrease in the durations of the pre-exposed percept. Moreover, the duration of the alternative percept was modulated by the specific characteristics of the pre-exposure, whereas the durations of the pre-exposed percept were not. The increase in duration of the alternative percept was larger when the pre-exposure had lasted longer and was larger after ambiguous pre-exposure than after unambiguous pre-exposure. Using a binocular rivalry stimulus we found analogous perceptual biases, while pre-exposure did not affect eye-bias. We conclude that previously perceived interpretations dominate at the onset of ambiguous sensory information, whereas alternative interpretations dominate prolonged viewing. Thus, at first instance ambiguous information seems to be judged using familiar percepts, while re-evaluation later on allows for alternative interpretations. PMID:22295095

[Airborne particles in a multi-wall carbon nanotube production plant: observation of particle emission and personal exposure 1: Measurement in the packing process].

PubMed

Takaya, Mitsutoshi; Serita, Fumio; Ono-Ogasawara, Mariko; Shinohara, Yasushi; Saito, Hiroyuki; Koda, Shigeki

2010-01-01

In order to assess the exposure risks of multiwall carbon nanotubes (MWCNT) for packing workers, we carried out real-time monitoring in the two types of packing facilities of MWCNT, and exposure measurements for the packing workers. In the real-time monitoring, a scanning mobility particle sizer (SMPS) and an optical particle counter (OPC) were used to measure nanoscale particles and sub-micron/micron scale particles, respectively. A personal sampler with PM 4.0 was used to measure the personal exposures in the packing facilities. One of the packing facilities is manually operated and the other is automated. The concentrations of airborne dust in both facilities were almost the same as each other at 0.24 mg/m(3) (total dust). However, the results of personal exposure measurements were quite different between the two facilities. The exposure concentrations of workers in the manually and automated operations were 2.39/0.39 (total/respirable) mg/m(3) and 0.29/0.08 (total/respirable) mg/m(3), respectively. From the time series study, submicron scale particles were released into the workplace air when the CNT products were put into temporary container bags from a hopper and manually packed into shipping bags. However, the task-related nanoscale particle release was not observed. The manual packing operation is one of the "hot spots" in MWCNT production facilities, and automation brings much improvement to reduce MWCNT exposure.

Extinction and anti-extinction: the "attentional waiting" hypothesis.

PubMed

Watling, Rosamond; Danckert, James; Linnell, Karina J; Cocchini, Gianna

2013-03-01

Patients with visual extinction have difficulty detecting a single contralesional stimulus when a second stimulus is simultaneously presented on the ipsilesional side. The rarely reported phenomenon of visual anti-extinction describes the opposite behavior, in which patients show greater difficulty in reporting a stimulus presented in isolation than they do in reporting 2 simultaneously presented stimuli. S. J. Goodrich and R. Ward (1997, Anti-extinction following unilateral parietal damage, Cognitive Neuropsychology, Vol. 14, pp. 595-612) suggested that visual anti-extinction is the result of a task-specific mechanism in which processing of the ipsilesional stimulus facilitates responses to the contralesional stimulus; in contrast, G. W. Humphreys, M. J. Riddoch, G. Nys, and D. Heinke (2002, Transient binding by time: Neuropsychological evidence from anti-extinction, Cognitive Neuropsychology, Vol. 19, pp. 361-380) suggested that temporal binding groups contralesional and ipsilesional stimuli together at brief exposure durations. We investigated extinction and anti-extinction phenomena in 3 brain-damaged patients using an extinction paradigm in which the stimulus exposure duration was systematically manipulated. Two patients showed both extinction and anti-extinction depending on the exposure duration of stimuli. Data confirmed the crucial role of duration in modulating the effect of extinction and anti-extinction. However, contrary to Humphreys and colleagues' (2002) single case, our patients showed extinction for short and anti-extinction for long exposure durations, suggesting that different mechanisms might underlie our patients' pattern of data. We discuss a novel "attentional waiting" hypothesis, which proposes that anti-extinction may be observed in patients showing extinction if the exposure duration of stimuli is increased. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Farm Animal Models of Organic Dust Exposure and Toxicity: Insights and Implications for Respiratory Health

PubMed Central

McClendon, Chakia J.; Gerald, Carresse L.; Waterman, Jenora T.

2016-01-01

Purpose of review Modern food animal production is a major contributor to the global economy, owing to advanced intensive indoor production facilities aimed at increasing market readiness and profit. Consequences of these advances are accumulation of dusts, gases and microbial products that diminish air quality within production facilities. Chronic inhalation exposure contributes to onset and exacerbation of respiratory symptoms and diseases in animals and workers. This article reviews literature regarding constituents of farm animal production facility dusts; animal responses to production building and organic dust exposure, and the effect of chronic inhalation exposure on pulmonary oxidative stress and inflammation. Recent findings –Porcine models of production facility and organic dust exposures reveal striking similarities to observations of human cells, tissues and clinical data. Oxidative stress plays a key role in mediating respiratory diseases in animals and humans, and enhancement of antioxidant levels through nutritional supplements can improve respiratory health. Summary – Pigs are well adapted to the exposures common to swine production buildings and thus serve as excellent models for facility workers. Insight for understanding mechanisms governing organic dust associated respiratory diseases may come from parallel comparisons between farmers and the animals they raise. PMID:25636160

Low Earth orbit thermal control coatings exposure flight tests: A comparison of U.S. and Russian results

NASA Technical Reports Server (NTRS)

Tribble, A. C.; Lukins, R.; Watts, E.; Naumov, S. F.; Sergeev, V. K.

1995-01-01

Both the United States (US) and Russia have conducted a variety of space environment effects on materials (SEEM) flight experiments in recent years. A prime US example was the Long Duration Exposure Facility (LDEF), which spent 5 years and 9 months in low Earth orbit (LEO) from April 1984 to January 1990. A key Russian experiment was the Removable Cassette Container experiment, (RCC-1), flown on the Mir Orbital Station from 11 January 1990 to 26 April 1991. This paper evaluates the thermal control coating materials data generated by these two missions by comparing: environmental exposure conditions, functionality and chemistry of thermal control coating materials, and pre- and post-flight analysis of absorptance, emittance, and mass loss due to atomic oxygen erosion. It will be seen that there are noticeable differences in the US and Russian space environment measurements and models, which complicates comparisons of environments. The results of both flight experiments confirm that zinc oxide and zinc oxide orthotitanate white thermal control paints in metasilicate binders (Z93, YB71, TP-co-2, TP-co-11, and TP-co-12), are the most stable upon exposure to the space environment. It is also seen that Russian flight materials experience broadens to the use of silicone and acrylic resin binders while the US relies more heavily on polyurethane.

Lead and methylene chloride exposures among automotive repair technicians.

PubMed

Enander, Richard T; Cohen, Howard J; Gute, David M; Brown, Linfield C; Desmaris, Anne Marie C; Missaghian, Richard

2004-02-01

Potential exposures among repair technicians engaged in vehicle resurfacing operations prior to spray painting have not been thoroughly characterized. Environmental and personal air monitoring conducted in the State of Rhode Island have shown that automotive repair technicians may be exposed to metal particulates in sanding dust and methylene chloride vapors during vehicle paint removal operations. Hand wipe samples demonstrated that metals in sanding dust adhered to the hands of workers throughout the duration of the work day and were available for incidental ingestion from the handling of food/nonfood items and hand-to-mouth contact. A blood lead (PbB) screening effort among 21 workers at 2 facilities showed that 4 non-/less-exposed workers had mean PbB levels at the U.S. geometric mean of 2.8 microg/dL, while 2 out of 9 (22%) dedicated vehicle repair technicians had PbB levels at or above 30 microg Pb/dL whole blood--the level for potential adverse reproductive effects. Methylene chloride exposures were also found to exceed the Occupational Safety and Health Administrations (OSHA) 8-hr time-weighted average (TWA) action level and permissible exposure limit (PEL) in a limited number of samples (120 and 26 ppm, integrated work shift samples). Our findings suggest that thousands of professional technicians and vocational high school students may be at increased risk of adverse reproductive and/or other systemic effects.

BMDO materials testing in the EOIM-3 experiment

NASA Technical Reports Server (NTRS)

Chung, Shirley Y.; Brinza, David E.; Minton, Timothy K.; Liang, Ranty H.

1995-01-01

The NASA Evaluation of Oxygen Interactions with Materials-3 (EOIM-3) experiment served as a testbed for a variety of materials that are candidates for Ballistic Missile Defense Organization (BMDO) space assets. The materials evaluated on this flight experiment were provided by BMDO contractors and technology laboratories. A parallel ground-based exposure evaluation was conducted using the Fast Atom Sample Tester (FAST) atomic-oxygen simulation facility at Physical Sciences, Inc. The EOIM-3 flight materials were exposed to an atomic oxygen fluence of approximately 2.3 x 10(exp 20) atoms/sq cm. The ground-based exposure fluence of 2.0 - 2.5 x 10(exp 20) atoms/sq cm permits direct comparison with that of the flight-exposed specimens. The results from the flight test conducted aboard STS-46 and the correlative ground-based exposure are summarized here. A more detailed correlation study is presented in the JPL Publication 93-31 entitled 'Flight-and Ground-Test Correlation Study of BMDO SDS Materials: Phase 1 Report'. In general, the majority of the materials survived the AO environment with their performance tolerances maintained for the duration of the exposure. Optical materials, baffles, and coatings performed extremely well as did most of the thermal coatings and tribological materials. A few of the candidate radiator, threat shielding, and structural materials showed significant degradation. Many of the coatings designed to protect against AO erosion of sensitive materials performed this function well.

Underwater temporary threshold shift in pinnipeds: effects of noise level and duration.

PubMed

Kastak, David; Southall, Brandon L; Schusterman, Ronald J; Kastak, Colleen Reichmuth

2005-11-01

Behavioral psychophysical techniques were used to evaluate the residual effects of underwater noise on the hearing sensitivity of three pinnipeds: a California sea lion (Zalophus californianus), a harbor seal (Phoca vitulina), and a northern elephant seal (Mirounga angustirostris). Temporary threshold shift (TTS), defined as the difference between auditory thresholds obtained before and after noise exposure, was assessed. The subjects were exposed to octave-band noise centered at 2500 Hz at two sound pressure levels: 80 and 95 dB SL (re: auditory threshold at 2500 Hz). Noise exposure durations were 22, 25, and 50 min. Threshold shifts were assessed at 2500 and 3530 Hz. Mean threshold shifts ranged from 2.9-12.2 dB. Full recovery of auditory sensitivity occurred within 24 h of noise exposure. Control sequences, comprising sham noise exposures, did not result in significant mean threshold shifts for any subject. Threshold shift magnitudes increased with increasing noise sound exposure level (SEL) for two of the three subjects. The results underscore the importance of including sound exposure metrics (incorporating sound pressure level and exposure duration) in order to fully assess the effects of noise on marine mammal hearing.

Duration and Timing of Exposure to Neighborhood Poverty and the Risk of Adolescent Parenthood

PubMed Central

Wodtke, Geoffrey T.

2013-01-01

Theory suggests that the impact of neighborhood poverty depends on both the duration and timing of exposure. Previous research, however, does not properly analyze the sequence of neighborhoods to which children are exposed throughout the early life course. This study investigates the effects of different longitudinal patterns of exposure to disadvantaged neighborhoods on the risk of adolescent parenthood. It follows a cohort of children in the PSID from age 4 to 19 and uses novel methods for time-varying exposures that overcome critical limitations of conventional regression when selection processes are dynamic. Results indicate that sustained exposure to poor neighborhoods substantially increases the risk of becoming a teen parent and that exposure to neighborhood poverty during adolescence may be more consequential than exposure earlier during childhood. PMID:23720166

Facilities and support systems for a 90-day test of a regenerative life support system

NASA Technical Reports Server (NTRS)

Malin, R. L.

1972-01-01

A 90-day test is reported of a regenerative life support system which was completed in a space station simulator. The long duration of the test and the fact that it was manned, imposed rigid reliability and safety requirements on the facility. Where adequate reliability could not be built into essential facility systems, either backup systems or components were provided. Awareness was intensified by: (1) placing signs on every piece of equipment that could affect the test, (2) painting switches on all breaker panels a bright contrasting color, (3) restricting access to the test control area, and (4) informing personnel in the facility (other than test personnel) of test activities. It is concluded that the basic facility is satisfactory for conducting long-duration manned tests, and it is recommended that all monitor and alarm functions be integrated into a single operation.

Drosophila melanogaster (fruit fly) locomotion during a sounding rocket flight

NASA Astrophysics Data System (ADS)

Miller, Mark S.; Keller, Tony S.

2008-05-01

The locomotor activity of young Drosophila melanogaster (fruit fly) was studied during a Nike-Orion sounding rocket flight, which included a short-duration microgravity exposure. An infrared monitoring system was used to determine the activity level, instantaneous velocity, and continuous velocity of 240 (120 male, 120 female) fruit flies. Individual flies were placed in chambers that limit their motion to walking. Chambers were oriented both vertically and horizontally with respect to the rocket's longitudinal axis. Significant changes in Drosophila locomotion patterns were observed throughout the sounding rocket flight, including launch, microgravity exposure, payload re-entry, and after ocean impact. During the microgravity portion of the flight (3.8 min), large increases in all locomotion measurements for both sexes were observed, with some measurements doubling compared to pad (1 G) data. Initial effects of microgravity were probably delayed due to large accelerations from the payload despining immediately before entering microgravity. The results indicate that short-duration microgravity exposure has a large effect on locomotor activity for both males and females, at least for a short period of time. The locomotion increases may explain the increased male aging observed during long-duration exposure to microgravity. Studies focusing on long-duration microgravity exposure are needed to confirm these findings, and the relationship of increased aging and locomotion.

Effects of Oral Exposure Duration and Gastric Energy Content on Appetite Ratings and Energy Intake in Lean Men

PubMed Central

Wijlens, Anne G. M.; de Graaf, Cees; Erkner, Alfrun; Mars, Monica

2016-01-01

Studies show that longer oral exposure to food leads to earlier satiation and lowers energy intake. Moreover, higher energy content of food has been shown to lead to higher satiety. Up to now, it has not been studied systematically how oral exposure duration and gastric energy content interact in satiety regulation. Thirty-seven men (22 ± 4 years, 22 ± 2 kg/m2) participated in a randomized cross-over trial, in which we independently manipulated: (1) oral exposure duration by modified sham feeding (MSF) for 1 or 8 min; and (2) energy content of gastric load (GL) by a nasogastric tube: 100 kcal/500 mL or 700 kcal/500 mL. Outcome measures were appetite ratings and subsequent energy intake from an ad libitum meal. Energy intake was 35% lower after the GLs with 700 kcal than with 100kcal (p < 0.0001). All appetite ratings were lower in the 700 kcal than in the 100 kcal treatments (area under the curve (AUC); p-values ≤ 0.002); fullness was higher and prospective consumption was lower in the 8 min than in the 1 min MSF treatments (AUC; p-values ≤ 0.02). In conclusion, the current showed that a GL of 700 kcal/500 mL vs. 100 kcal/500 mL increased satiety and lowered energy intake. No additional effects of oral exposure duration could be observed, presumably due to the high contrast in energy between the manipulations. Future research should also focus on the role of oral exposure as such and not only the duration. PMID:26821045

Spacecraft contamination issues from LDEF: Issues for design

NASA Technical Reports Server (NTRS)

Pippin, Gary; Crutcher, Russ

1993-01-01

Many contamination sources have been identified on the Long Duration Exposure Facility (LDEF). Effects of contamination from these sources are being quantified and have been reported on in several papers. For a designer, the essential question is how much contamination from all sources can be tolerated without causing a given spacecraft system to degrade below a critical performance level, or fail altogether. Even a rudimentary knowledge of the mechanisms by which molecular and particulate contamination can occur will allow simple design options to be chosen to circumvent potential contamination problems and reduce contamination levels. Because of the varied nature and condition of hardware used on LDEF experiments, examples of many types of contamination were seen and these provide a useful guide to expected performance of many types of materials in space environments.

Preliminary analysis of LDEF instrument A0187-1: Chemistry of Micrometeoroids Experiment

NASA Technical Reports Server (NTRS)

Hoerz, Friedrich; Bernhard, Ronald P.; Warren, Jack; See, Thomas H.; Brownlee, Donald E.; Laurance, Mark R.; Messenger, Scott; Peterson, Robert B.

1992-01-01

The Chemistry of Micrometeoroids Experiment (CME) exposed approximately 0.8 sq. m of gold on the Long Duration Exposure Facility's (LDEF's) trailing edge (location A03) and approximately 1.1 sq. m of aluminum in the forward-facing A11 location. The most significant results to date relate to the discovery of unmelted pyroxene and olivine fragments associated with natural cosmic dust impacts. The latter are sufficiently large for detailed phase studies, and they serve to demonstrate that recovery of unmelted dust fragments is a realistic prospect for further dust experiments that will employ more advanced collector media. We also discovered that man-made debris impacts occur on the LDEF's trailing edge with substantially higher frequency than expected, suggesting that orbital debris in highly elliptical orbits may have been somewhat underestimated.

Investigation of Teflon FEP Embrittlement on Spacecraft in Low-Earth Orbit

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Banks, Bruce A.

1997-01-01

Teflon fluorinated ethylene propylene (FEP) (DuPont) is commonly used on exterior spacecraft surfaces for thermal control in the low-Earth orbit environment. Silverized or aluminized Teflon FEP is used for the outer layers of the thermal control blanket because of its high reflectance, low solar absorptance, and high thermal emittance. Teflon FEP is also desirable because, compared with other spacecraft polymers (such as Kapton), it has relatively high resistance to atomic oxygen erosion. Because of its comparably low atomic oxygen erosion yield, Teflon FEP has been used unprotected in the space environment. Samples of Teflon FEP from the Long Duration Exposure Facility (LDEF) and the Hubble Space Telescope (retrieved during its first servicing mission) were evaluated for solar-induced embrittlement and for synergistic effects of solar degradation and atomic oxygen.

Perioperative abstinence from cigarettes: physiologic and clinical consequences.

PubMed

Warner, David O

2006-02-01

Chronic exposure to cigarette smoke produces profound changes in physiology that may alter responses to perioperative interventions and contribute to perioperative morbidity. Because of smoke-free policies in healthcare facilities, all smokers undergoing surgery are abstinent from cigarettes for at least some period of time so that all are in various stages of recovery from the effects of smoke. Understanding this recovery process will help perioperative physicians better treat these patients. This review examines current knowledge regarding how both short-term (duration ranging from hours to weeks) and long-term smoking cessation affects selected physiology and pathophysiology of particular relevance to perioperative outcomes and how these changes affect perioperative risk. It will also consider current evidence regarding how nicotine replacement therapy, a valuable adjunct to help patients maintain abstinence, may affect perioperative physiology.

Long Duration Exposure Facility Mini-Data Base User`s Guide: Macintosh version. (Diskette)

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

Bohnhoff-Hlavacek, G.; Pippin, H.G.; Dursch, H.W.

1995-04-01

One of the objectives of the LDEF Special Investigation Group (SIG) was to develop a LDEF data base that identifies the experiment objectives and hardware flown, summarizes results and conclusions, and provides a system analysis overview, including spacecraft design guidelines and space environmental effects. Compiling the information into an easily accessible data base format, and making it available to the space community was a major task accomplished by the System and Materials SIG effort beginning in 1981. Included in this document is a short user`s manual for the LDEF Mini-Data Bases. The user`s manual contains pertinent examples from the datamore » base on specifically how to access and work with the LDEF information. Accompanying this document are the mini-data bases on disk.« less

LDEF electronic systems: Successes, failures, and lessons

NASA Technical Reports Server (NTRS)

Miller, Emmett; Porter, Dave; Smith, Dave; Brooks, Larry; Levorsen, Joe; Mulkey, Owen

1991-01-01

Following the Long Duration Exposure Facility (LDEF) retrieval, the Systems Special Investigation Group (SIG) participated in an extensive series of tests of various electronic systems, including the NASA provided data and initiate systems, and some experiment systems. Overall, these were found to have performed remarkably well, even though most were designed and tested under limited budgets and used at least some nonspace qualified components. However, several anomalies were observed, including a few which resulted in some loss of data. The postflight test program objectives, observations, and lessons learned from these examinations are discussed. All analyses are not yet complete, but observations to date will be summarized, including the Boeing experiment component studies and failure analysis results related to the Interstellar Gas Experiment. Based upon these observations, suggestions for avoiding similar problems on future programs are presented.

Instellar Gas Experiment (IGE): Testing interstellar gas particles to provide information on the processes of nucleosynthesis in the big bang stars and supernova

NASA Technical Reports Server (NTRS)

Lind, Don

1985-01-01

The Interstellar Gas Experiment (IGE) is designed to collect particles of the interstellar gas - a wind of interstellar media particles moving in the vicinity of the solar system. These particles will be returned to earth where the isotopic ratios of the noble gases among these particles will be measured. IGE was designed and programmed to expose 7 sets of six copper-beryllium metallic collecting foils to the flux of neutral interstellar gas particles which penetrate the heliosphere to the vicinity of the earth's orbit. These particles are trapped in the collecting foils and will be returned to earth for mass-spectrographic analysis when Long Duration Exposure Facility (LDEF) on which IGE was launched, is recovered.

Effects of space environment on structural materials - A preliminary study and development of materials characterization protocols

NASA Technical Reports Server (NTRS)

Miglionico, C.; Stein, C.; Murr, L. E.

1991-01-01

A preliminary study of materials exposed in space in LEO for nearly six years in the NASA Long-Duration Exposure Facility is presented. It is demonstrated that it will be necessary to isolate surface debris and reaction products from materials exposed in space. Replication techniques originally designed for electron microscopy examination of surfaces can be applied to lift off and isolate such surface features. Debris and reaction products were examined through a variety of analytical techniques, including the surface morphology by SEM, and internal microstructures by STEM and TEM, EDS, and SAD. The results illustrate the role that atomic oxygen and micrometeorites play in surface alteration and reaction in LEO space environments, as well as the role of debris created from other proximate materials.

Future radiation measurements in low Earth orbit

NASA Technical Reports Server (NTRS)

Adams, James H., Jr.

1993-01-01

The first Long Duration Exposure Facility (LDEF) mission has demonstrated the value of the LDEF concept for deep surveys of the space radiation environment. The kinds of measurements that could be done on a second LDEF mission are discussed. Ideas are discussed for experiments which: (1) capitalize on the discoveries from LDEF 1; (2) take advantage of LDEF's unique capabilities; and (3) extend the investigations begun on LDEF 1. These ideas have been gleaned from investigators on LDEF 1 and others interested in the space radiation environment. They include new approaches to the investigation of Be-7 that was discovered on LDEF 1, concepts to obtain further information on the ionic charge state of cosmic rays and other energetic particles in space and other ideas to extend the investigations begun on LDEF 1.

The Limited Impact of Exposure Duration on Holistic Word Processing.

PubMed

Chen, Changming; Abbasi, Najam Ul Hasan; Song, Shuang; Chen, Jie; Li, Hong

2016-01-01

The current study explored the impact of stimuli exposure duration on holistic word processing measured by the complete composite paradigm (CPc paradigm). The participants were asked to match the cued target parts of two characters which were presented for either a long (600 ms) or a short duration (170 ms). They were also tested by two popular versions of the CPc paradigm: the "early-fixed" task where the attention cue was visible from the beginning of each trial at a fixed position, and the "delayed-random" task where the cue showed up after the study character at random locations. The holistic word effect, as indexed by the alignment × congruency interaction, was identified in both tasks and was unaffected by the stimuli duration in both tasks. Meanwhile, the "delayed-random" task did not bring about larger holistic word effect than the "early-fixed" task. These results suggest the exposure duration (from around 150 to 600 ms) has a limited impact on the holistic word effect, and have methodological implications for experiment designs in this field.

Attention, Exposure Duration, and Gaze Shifting in Naming Performance

ERIC Educational Resources Information Center

Roelofs, Ardi

2011-01-01

Two experiments are reported in which the role of attribute exposure duration in naming performance was examined by tracking eye movements. Participants were presented with color-word Stroop stimuli and left- or right-pointing arrows on different sides of a computer screen. They named the color attribute and shifted their gaze to the arrow to…

Pivotal ERIVANCE basal cell carcinoma (BCC) study: 12-month update of efficacy and safety of vismodegib in advanced BCC.

PubMed

Sekulic, Aleksandar; Migden, Michael R; Lewis, Karl; Hainsworth, John D; Solomon, James A; Yoo, Simon; Arron, Sarah T; Friedlander, Philip A; Marmur, Ellen; Rudin, Charles M; Chang, Anne Lynn S; Dirix, Luc; Hou, Jeannie; Yue, Huibin; Hauschild, Axel

2015-06-01

Primary analysis from the pivotal ERIVANCE BCC study resulted in approval of vismodegib, a Hedgehog pathway inhibitor indicated for treatment of adults with metastatic or locally advanced basal cell carcinoma (BCC) that has recurred after surgery or for patients who are not candidates for surgery or radiation. An efficacy and safety analysis was conducted 12 months after primary analysis. This was a multinational, multicenter, nonrandomized, 2-cohort study in patients with measurable and histologically confirmed locally advanced or metastatic BCC taking oral vismodegib (150 mg/d). Primary outcome measure was objective response rate (complete and partial responses) assessed by independent review facility. After 12 months of additional follow-up, median duration of exposure to vismodegib was 12.9 months. Objective response rate increased from 30.3% to 33.3% in patients with metastatic disease, and from 42.9% to 47.6% in patients with the locally advanced form. Median duration of response in patients with locally advanced BCC increased from 7.6 to 9.5 months. No new safety signals emerged with extended treatment duration. Limitations include low prevalence of advanced BCC and challenges of designing a study with heterogenous manifestations. The 12-month update of the study confirms the efficacy and safety of vismodegib in management of advanced BCC. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

Effect of ventilation velocity on hexavalent chromium and isocyanate exposures in aircraft paint spraying.

PubMed

Bennett, James; Marlow, David; Nourian, Fariba; Breay, James; Feng, Amy; Methner, Mark

2018-03-01

Exposure control system performance was evaluated during aircraft paint spraying at a military facility. Computational fluid dynamics (CFD) modeling, tracer gas testing, and exposure monitoring examined contaminant exposure vs. crossflow ventilation velocity. CFD modeling using the RNG k-ϵ turbulence model showed exposures to simulated methyl isobutyl ketone of 294 and 83.6 ppm, as a spatial average of five worker locations, for velocities of 0.508 and 0.381 m/s (100 and 75 fpm), respectively. In tracer gas experiments, observed supply/exhaust velocities of 0.706/0.503 m/s (136/99 fpm) were termed full-flow, and reduced velocities were termed 3/4-flow and half-flow. Half-flow showed higher tracer gas concentrations than 3/4-flow, which had the lowest time-averaged concentration, with difference in log means significant at the 95% confidence level. Half-flow compared to full-flow and 3/4-flow compared to full-flow showed no statistically significant difference. CFD modeling using these ventilation conditions agreed closely with the tracer results for the full-flow and 3/4-flow comparison, yet not for the 3/4-flow and half-flow comparison. Full-flow conditions at the painting facility produced a velocity of 0.528 m/s (104 fpm) midway between supply and exhaust locations, with the supply rate of 94.4 m 3 /s (200,000 cfm) exceeding the exhaust rate of 68.7 m 3 /s (146,000 cfm). Ventilation modifications to correct this imbalance created a midhangar velocity of 0.406 m/s (80.0 fpm). Personal exposure monitoring for two worker groups-sprayers and sprayer helpers ("hosemen")-compared process duration means for the two velocities. Hexavalent chromium (Cr[VI]) exposures were 500 vs. 360 µg/m 3 for sprayers and 120 vs. 170 µg/m 3 for hosemen, for 0.528 m/s (104 fpm) and 0.406 m/s (80.0 fpm), respectively. Hexamethylene diisocyanate (HDI) monomer means were 32.2 vs. 13.3 µg/m 3 for sprayers and 3.99 vs. 8.42 µg/m 3 for hosemen. Crossflow velocities affected exposures inconsistently, and local work zone velocities were much lower. Aircraft painting contaminant control is accomplished better with the unidirectional crossflow ventilation presented here than with other observed configurations. Exposure limit exceedances for this ideal condition reinforce continued use of personal protective equipment.

Proteomic Analyses of Corneal Tissue Subjected to Alkali Exposure

PubMed Central

Parikh, Toral; Eisner, Natalie; Venugopalan, Praseeda; Yang, Qin; Lam, Byron L.

2011-01-01

Purpose. To determine whether exposure to alkaline chemicals results in predictable changes in corneal protein profile. To determine whether protein profile changes are indicative of severity and duration of alkali exposure. Methods. Enucleated bovine and porcine (n = 59 each) eyes were used for exposure to sodium, ammonium, and calcium hydroxide, respectively. Eyes were subjected to fluorescein staining, 5-bromo-2′-deoxy-uridine (BrdU) labeling. Excised cornea was subjected to protein extraction, spectrophotometric determination of protein amount, dynamic light scattering and SDS-PAGE profiling, mass spectrometric protein identification, and iTRAQ-labeled quantification. Select identified proteins were subjected to Western blot and immunohistochemical analyses. Results. Alkali exposure resulted in lower protein extractability from corneal tissue. Elevated aggregate formation was found with strong alkali exposure (sodium hydroxide>ammonium, calcium hydroxide), even with a short duration of exposure compared with controls. The protein yield after exposure varied as a function of postexposure time. Protein profiles changed because of alkali exposure. Concentration and strength of the alkali affected the profile change significantly. Mass spectrometry identified 15 proteins from different bands with relative quantification. Plexin D1 was identified for the first time in the cornea at a protein level that was further confirmed by Western blot and immunohistochemical analyses. Conclusions. Exposure to alkaline chemicals results in predictable and reproducible changes in corneal protein profile. Stronger alkali, longer durations, or both, of exposure resulted in lower yields and significant protein profile changes compared with controls. PMID:20861482

14 CFR 158.33 - Duration of authority to impose a PFC before project implementation.

Code of Federal Regulations, 2011 CFR

2011-01-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.33 Duration of authority to impose a PFC before project implementation. (a) A... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Duration of authority to impose a PFC...

14 CFR 158.33 - Duration of authority to impose a PFC before project implementation.

Code of Federal Regulations, 2010 CFR

2010-01-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.33 Duration of authority to impose a PFC before project implementation. (a) A... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Duration of authority to impose a PFC...

14 CFR 158.33 - Duration of authority to impose a PFC before project implementation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.33 Duration of authority to impose a PFC before project implementation. (a) A... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Duration of authority to impose a PFC...

14 CFR 158.33 - Duration of authority to impose a PFC before project implementation.

Code of Federal Regulations, 2013 CFR

2013-01-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.33 Duration of authority to impose a PFC before project implementation. (a) A... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Duration of authority to impose a PFC...

14 CFR 158.33 - Duration of authority to impose a PFC before project implementation.

Code of Federal Regulations, 2012 CFR

2012-01-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Application and Approval § 158.33 Duration of authority to impose a PFC before project implementation. (a) A... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Duration of authority to impose a PFC...

Effect of Air and Vacuum Storage on the Tensile Properties of X-Ray Exposed Aluminized-FEP

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Gummow, Jonathan D.

2000-01-01

Metallized Teflon(Registered Trademark) FEP (fluorinated ethylene propylene), a common spacecraft thermal control material, from the exterior layer of the Hubble Space Telescope (HST) has become embrittled and suffers from extensive cracking. Teflon samples retrieved during Hubble servicing missions and from the Long Duration Exposure Facility (LDEF) indicate that there may be continued degradation in tensile properties over time. An investigation has been conducted to evaluate the effect of air and vacuum storage on the mechanical properties of x-ray exposed FEP. Aluminized-FEP (Al-FEP) tensile samples were irradiated with 15.3 kV Cu x-rays and stored in air or under vacuum for various time periods. Tensile data indicate that samples stored in air display larger decreases in tensile properties than for samples stored under vacuum. Air-stored samples developed a hazy appearance, which corresponded to a roughening of the aluminized surface. Optical property changes were also characterized. These findings indicate that air exposure plays a role in the degradation of irradiated FEP, therefore proper sample handling and storage is necessary with materials retrieved from space.

EXTRAPOLATION METHOD FOR MAXIMAL AND 24-H AVERAGE LTE TDD EXPOSURE ESTIMATION.

PubMed

Franci, D; Grillo, E; Pavoncello, S; Coltellacci, S; Buccella, C; Aureli, T

2018-01-01

The Long-Term Evolution (LTE) system represents the evolution of the Universal Mobile Telecommunication System technology. This technology introduces two duplex modes: Frequency Division Duplex and Time Division Duplex (TDD). Despite having experienced a limited expansion in the European countries since the debut of the LTE technology, a renewed commercial interest for LTE TDD technology has recently been shown. Therefore, the development of extrapolation procedures optimised for TDD systems becomes crucial, especially for the regulatory authorities. This article presents an extrapolation method aimed to assess the exposure to LTE TDD sources, based on the detection of the Cell-Specific Reference Signal power level. The method introduces a βTDD parameter intended to quantify the fraction of the LTE TDD frame duration reserved for downlink transmission. The method has been validated by experimental measurements performed on signals generated by both a vector signal generator and a test Base Transceiver Station installed at Linkem S.p.A facility in Rome. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effects of long term space environment exposure on optical substrates and coatings (S0050-2)

NASA Technical Reports Server (NTRS)

Harvey, Keith; Mustico, Arthur; Vallimont, John

1993-01-01

Eastman Kodak Company included twelve substrate and coating samples on the Long Duration Exposure Facility (LDEF) structure. There were three Fused Silica and three Ultra Low Expansion (ULE) uncoated glass samples, two ULE samples with a high reflectance silver coating, two Fused Silica samples with an antireflectance coating, and two Fused silica samples with a solar rejection coating. A set of duplicate control samples was also manufactured and stored in a controlled environment for comparison purposes. Kodak's samples were included as a subset of the Georgia Institute of Technology tray, which was located on row 5-E, tray S0050-2. This placed the samples on the trailing edge of the structure, which protected them from the effects of atomic oxygen bombardment. An evaluation of the flight samples for effects from the 5 year mission showed that a contaminant was deposited on the samples, a micrometeoroid impact occurred on one of the samples, and the radiation darkening which was expected for the glass did not occur. The results are listed in more detail.

LDEF materials results for spacecraft applications: Executive summary

NASA Astrophysics Data System (ADS)

Whitaker, A. F.; Dooling, D.

1995-03-01

To address the challenges of space environmental effects, NASA designed the Long Duration Exposure Facility (LDEF) for an 18-month mission to expose thousands of samples of candidate materials that might be used on a space station or other orbital spacecraft. LDEF was launched in April 1984 and was to have been returned to Earth in 1985. Changes in mission schedules postponed retrieval until January 1990, after 69 months in orbit. Analyses of the samples recovered from LDEF have provided spacecraft designers and managers with the most extensive data base on space materials phenomena. Many LDEF samples were greatly changed by extended space exposure. Among even the most radially altered samples, NASA and its science teams are finding a wealth of surprising conclusions and tantalizing clues about the effects of space on materials. Many were discussed at the first two LDEF results conferences and subsequent professional papers. The LDEF Materials Results for Spacecraft Applications Conference was convened in Huntsville to discuss implications for spacecraft design. Already, paint and thermal blanket selections for space station and other spacecraft have been affected by LDEF data. This volume synopsizes those results.

Results from the testing and analysis of LDEF batteries

NASA Technical Reports Server (NTRS)

Spear, Steve; Dursch, Harry; Johnson, Chris

1992-01-01

Batteries were used on the Long Duration Exposure Facility (LDEF) to provide power to both the active experiments and the experiment support equipment such as the Experiment Initiative System, Experiment Power and Data System (data acquisition system), and the Environment Exposure Control Canisters. Three different types of batteries were used: lithium sulfur dioxide (LiSO2), lithium carbon monofluoride (LiCF), and nickel cadmium (NiCd). A total of 92 LiSO2, 10 LiCF, and 1 NiCd batteries were flown on the LDEF. In addition, approximately 20 LiSO2 batteries were kept in cold storage at NASA LaRC. The various investigations and post-flight analyses of the flight and control batteries are reviewed. The primary objectives of these studies was to identify degradation modes (if any) of the batteries and to provide information useful to future spacecraft missions. Systems SIG involvement in the post-flight evaluation of LDEF batteries was two-fold: (1) to fund SAFT (original manufacturer of the LiSO2 batteries) to perform characterization of 13 LiSO2 batteries (10 flight and 3 control batteries); and (2) to integrate investigator results.

LDEF materials results for spacecraft applications: Executive summary

NASA Technical Reports Server (NTRS)

Whitaker, A. F. (Compiler); Dooling, D. (Compiler)

1995-01-01

To address the challenges of space environmental effects, NASA designed the Long Duration Exposure Facility (LDEF) for an 18-month mission to expose thousands of samples of candidate materials that might be used on a space station or other orbital spacecraft. LDEF was launched in April 1984 and was to have been returned to Earth in 1985. Changes in mission schedules postponed retrieval until January 1990, after 69 months in orbit. Analyses of the samples recovered from LDEF have provided spacecraft designers and managers with the most extensive data base on space materials phenomena. Many LDEF samples were greatly changed by extended space exposure. Among even the most radially altered samples, NASA and its science teams are finding a wealth of surprising conclusions and tantalizing clues about the effects of space on materials. Many were discussed at the first two LDEF results conferences and subsequent professional papers. The LDEF Materials Results for Spacecraft Applications Conference was convened in Huntsville to discuss implications for spacecraft design. Already, paint and thermal blanket selections for space station and other spacecraft have been affected by LDEF data. This volume synopsizes those results.

NASA's Space Environments and Effects (SEE) Program

NASA Technical Reports Server (NTRS)

Minor, Jody

2001-01-01

The return of the Long Duration Exposure Facility (LDEF) in 1990 brought a wealth of space exposure data on materials, paints, solar cells, adhesives and other data on the many space environments. The effects of the harsh space environments can provide damaging or even disabling effects on a spacecraft, its sub-systems, materials and instruments. In partnership with industry, academia, and other US and international government agencies, the National Aeronautics & Space Administration's (NASA's) Space Environments & Effects (SEE) Program defines the space environments and provides technology development to accommodate or mitigate these harmful environments on the spacecraft. This program (agency-wide in scope but managed at the Marshall Space Flight Center) provides a very comprehensive and focused approach to understanding the space environment. It does this by defining the best techniques for both flight- and groundbased experimentation, updating models which predict both the environments and the environmental effects on spacecraft and ensuring that this information is properly maintained and inserted into spacecraft design programs. This paper will describe the current SEE Program and discuss several current technology development activities associated with the spacecraft charging phenomenon.

Contamination Examples and Lessons from Low Earth Orbit Experiments and Operational Hardware

NASA Technical Reports Server (NTRS)

Pippin, Gary; Finckenor, Miria M.

2009-01-01

Flight experiments flown on the Space Shuttle, the International Space Station, Mir, Skylab, and free flyers such as the Long Duration Exposure Facility, the European Retrievable Carrier, and the EFFU, provide multiple opportunities for the investigation of molecular contamination effects. Retrieved hardware from the Solar Maximum Mission satellite, Mir, and the Hubble Space Telescope has also provided the means gaining insight into contamination processes. Images from the above mentioned hardware show contamination effects due to materials processing, hardware storage, pre-flight cleaning, as well as on-orbit events such as outgassing, mechanical failure of hardware in close proximity, impacts from man-made debris, and changes due to natural environment factors.. Contamination effects include significant changes to thermal and electrical properties of thermal control surfaces, optics, and power systems. Data from several flights has been used to develop a rudimentary estimate of asymptotic values for absorptance changes due to long-term solar exposure (4000-6000 Equivalent Sun Hours) of silicone-based molecular contamination deposits of varying thickness. Recommendations and suggestions for processing changes and constraints based on the on-orbit observed results will be presented.

48 CFR 42.402 - Visits to contractors' facilities.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Visits to contractors... contractors' facilities. (a) Government personnel planning to visit a contractor's facility in connection with... positions, and security clearances. (2) Date and duration of visit. (3) Name and address of contractor and...

Western Canada study of animal health effects associated with exposure to emissions from oil and natural gas field facilities. Study design and data collection II. Location of study herds relative to the oil and gas industry in Western Canada.

PubMed

Waldner, Cheryl L

2008-01-01

During the late part of 2000 and early months of 2001, project veterinarians recruited 205 beef herds to participate in a study of the effects of emissions from the upstream oil and gas industry on cattle reproduction and health. Researchers developed herd-selection criteria to optimize the range of exposure to facilities, including oil and gas wells, battery sites, and gas-gathering and gas-processing facilities across the major cattle-producing areas of Western Canada. Herds were initially selected on the basis of a ranking system of exposure potential on the basis of herd-owner reports of the locations of their operations in relation to oil and gas industry facilities. At the end of the study, researchers summarized data obtained from provincial regulatory agencies on facility location and reported flaring and venting volumes for each herd and compared these data to the original rankings of herd-exposure potential. Through this selection process, the researchers were successful in obtaining statistically significant differences in exposure to various types of oil and gas facility types and reported emissions among herds recruited for the study.

Penetration rates over 30 years in the space age

NASA Technical Reports Server (NTRS)

Mcdonnell, J. A. M.; Baron, J. M.

1995-01-01

Experimental data from spacecraft providing impact penetration rates and cratering for metallic targets is reviewed. Data includes NASA Explorers 16 and 23 and the Pegasus series, the second US-UK satellite Ariel 2, Space Shuttle STS-3 (MFE), recovered surfaces on Solar Max Satellite, The Long Duration Exposure Facility (LDEF) and EuReCa TiCCE. Factors concerning exposure to the environment are considered and, especially, material properties which affect the penetration resistance. Reference to a common material, Aluminum alloy 2024-T3, is effected and the data then compared to define firstly an average impact flux over the period. The data is examined, in the context of possible satellite and space debris growth rates, to determine the constancy of the flux. This also provides strong constraints on the current space debris component. It is found that the impact data are consistent with domination by natural meteoroid sources. Growth rates are not evident within the period 1980-1990 and Eureca TiCCE fluxes in 1993, for particles penetrating foils of around 10 microns thickness, supports the constancy of the flux. At larger dimensions the 1993 Eureca TiCCE fluxes show an 8-fold increase but this is considered not inconsistent with the selective exposure to meteoroid streams of a satellite stabilized in heliocentric co-ordinates for an 11 month period.

Quantified activity pattern data from 6 to 27-month-old farmworker children for use in exposure assessment.

PubMed

Beamer, Paloma; Key, Maya E; Ferguson, Alesia C; Canales, Robert A; Auyeung, Willa; Leckie, James O

2008-10-01

This study was conducted to describe exposure prone behaviors of infants and toddlers in the farmworker community. Analysis of hand and mouth contact frequencies and durations aids understanding of how children interact with their environment and are exposed via contact with surfaces. All 23 participating children (8 female infants, 5 male infants, 5 female toddlers and 5 male toddlers) lived with at least one farmworker. Children were videotaped at home for 2-6 h. Video footage was translated into micro-level activity time series (MLATS) for both hands and the mouth. MLATS were processed to calculate hourly duration in microenvironments, contact frequency, hourly contact duration and median contact duration. The median hourly duration spent indoors was 53 min/h. The median hand-to-mouth frequency was 15.2 events/h and the median object-to-mouth frequency was 27.2 events/h. The hourly mouthing duration was 1.2 and 2.2 min/h with the hands and objects, respectively. The median mouthing duration with hands and objects was 2 s. The median contact frequency for both hands combined was 689.4 events/h with an hourly contact duration of 100.5 min/h and a median contact duration of 3s. Infants had higher mouthing frequencies with non-dietary objects while toddlers had higher mouthing frequencies with objects associated with pica (i.e., paper). Boys had higher contact frequencies while girls had longer contact durations. These sub-group differences indicate factors such as age and gender should be accounted for when conducting exposure assessments. Contact frequencies in this study are higher than current US EPA recommendations, questioning their protective value for infants and toddlers.

Quantified Activity Pattern Data from 6-to-27-Month-Old Farmworker Children for Use in Exposure Assessment

PubMed Central

Beamer, Paloma; Key, Maya E.; Ferguson, Alesia C.; Canales, Robert A.; Auyeung, Willa; Leckie, James O.

2008-01-01

This study was conducted to describe exposure prone behaviors of infants and toddlers in the farmworker community. Analysis of hand and mouth contact frequencies and durations aids understanding of how children interact with their environment and are exposed via contact with surfaces. All 23 participating children (8 female infants, 5 male infants, 5 female toddlers and 5 male toddlers) lived with at least one farmworker. Children were videotaped at home for 2–6 hours. Video footage was translated into micro- level activity time series (MLATS) for both hands and the mouth. MLATS were processed to calculate hourly duration in microenvironments, contact frequency, hourly contact duration and median contact duration. The median hourly duration spent indoors was 53 min/hr. The median hand-to-mouth frequency was 15.2 events/hr and the median object-to-mouth frequency was 27.2 events/hr. The hourly mouthing duration was 1.2 and 2.2 min/hr with the hands and objects respectively. The median mouthing duration with hands and objects was 2 seconds. The median contact frequency for both hands combined was 689.4 events/hr with an hourly contact duration of 100.5 min/hr and a median contact duration of 3 seconds. Infants had higher mouthing frequencies with non-dietary objects while toddlers had higher mouthing frequencies with objects associated with pica (i.e., paper). Boys had higher contact frequencies while girls had longer contact durations. These sub-group differences indicate factors such as age and gender should be accounted for when conducting exposure assessments. Contact frequencies in this study are higher than current U.S. EPA recommendations, questioning their protective value for infants and toddlers. PMID:18723168

A carbon fiber exposure test facility and instrumentation

NASA Technical Reports Server (NTRS)

Newcomb, A. L., Jr.

1980-01-01

A facility to evaluate the risk associated with the exposure of electrical and electronic equipment to airborne carbon/graphite fibers was constructed. A wide variety of instrumentation is described and illustrated.

Impact of Elevated Core Body Temperature on Attention Networks.

PubMed

Liu, Kai; Jiang, Qingjun; Li, Li; Li, Bo; Yang, Zhen; Qian, Shaowen; Li, Min; Sun, Gang

2015-12-01

Cognitive function can be impaired after passive heat exposure and with an elevation in core body temperature (Tcore). This study examined the dynamic correlation among passive heat exposure, Tcore, and cognition. We gave the Attention Network Test of alerting, orienting, and executive control to five groups of five young men who were being exposed to a hyperthermic condition (50°C, 40% relative humidity) for 0, 10, 20, 30, or 40 minutes. We used the participants' reaction time, accuracy (correct responses), efficiency (accuracy÷reaction time), and Tcore to estimate optimal curve models for best fit of data. We could not estimate an appropriate curve model for either alerting or orienting with Tcore, change in Tcore, or duration of passive heat exposure. We estimated quadratic models for Tcore and duration (adjusted R=0.752), change in Tcore and duration (0.906), executive control score and duration (0.509), and efficiency of executive control and duration (0.293). We estimated linear models for executive control score and Tcore (0.479), efficiency of executive control and Tcore (0.261), executive control score and change in Tcore (0.279), and efficiency of executive control and change in Tcore (0.262). Different attentional abilities had different sensitivities to thermal stress. Executive control of attention deteriorated linearly with a rise in Tcore within the normal physiologic range, but deteriorated nonlinearly with longer passive heat exposure.

Two forms of persistence in visual information processing.

PubMed

Di Lollo, Vincent; Dixon, Peter

1988-11-01

Iconic memory, which was initially regarded as a unitary phenomenon, has since been subdivided into several components. In the present work we examined the joint effects of two such components (visible persistence and the visual analog representation) on performance in a partial report task. The display consisted of 15 alphabetic characters arranged around the perimeter of an imaginary circle on the face of an oscilloscope. The observer named the character singled out by a bar-probe. Two factors were varied: exposure duration of the array (10, 50, 100, 150, 200, 300, 400 or 500 ms) and duration of blank period (interstimulus interval, ISI) between the termination of the array and the onset of the probe (0, 50, 100, 150, or 200 ms). Performance was progressively impaired as both exposure duration and ISI were increased. The results were explained in terms of a probabilistic combinatorial model in which the timecourses of visible persistence and of the visual analog representation are regarded as time-locked to the onset and to the end of stimulation, respectively. The impairing effect of exposure duration was attributed to the relatively high spatial demands of the task that could be met optimally by information in visible persistence (which declines as a function of exposure duration), but less adequately by information in the visual analog representation. A second experiment, employing a task with lesser spatial demands, confirmed this interpretation.

The Diesel Exhaust in Miners Study: IV. Estimating historical exposures to diesel exhaust in underground non-metal mining facilities.

PubMed

Vermeulen, Roel; Coble, Joseph B; Lubin, Jay H; Portengen, Lützen; Blair, Aaron; Attfield, Michael D; Silverman, Debra T; Stewart, Patricia A

2010-10-01

We developed quantitative estimates of historical exposures to respirable elemental carbon (REC) for an epidemiologic study of mortality, including lung cancer, among diesel-exposed miners at eight non-metal mining facilities [the Diesel Exhaust in Miners Study (DEMS)]. Because there were no historical measurements of diesel exhaust (DE), historical REC (a component of DE) levels were estimated based on REC data from monitoring surveys conducted in 1998-2001 as part of the DEMS investigation. These values were adjusted for underground workers by carbon monoxide (CO) concentration trends in the mines derived from models of historical CO (another DE component) measurements and DE determinants such as engine horsepower (HP; 1 HP = 0.746 kW) and mine ventilation. CO was chosen to estimate historical changes because it was the most frequently measured DE component in our study facilities and it was found to correlate with REC exposure. Databases were constructed by facility and year with air sampling data and with information on the total rate of airflow exhausted from the underground operations in cubic feet per minute (CFM) (1 CFM = 0.0283 m³ min⁻¹), HP of the diesel equipment in use (ADJ HP), and other possible determinants. The ADJ HP purchased after 1990 (ADJ HP₁₉₉₀(+)) was also included to account for lower emissions from newer, cleaner engines. Facility-specific CO levels, relative to those in the DEMS survey year for each year back to the start of dieselization (1947-1967 depending on facility), were predicted based on models of observed CO concentrations and log-transformed (Ln) ADJ HP/CFM and Ln(ADJ HP₁₉₉₀(+)). The resulting temporal trends in relative CO levels were then multiplied by facility/department/job-specific REC estimates derived from the DEMS surveys personal measurements to obtain historical facility/department/job/year-specific REC exposure estimates. The facility-specific temporal trends of CO levels (and thus the REC estimates) generated from these models indicated that CO concentrations had been generally greater in the past than during the 1998-2001 DEMS surveys, with the highest levels ranging from 100 to 685% greater (median: 300%). These levels generally occurred between 1970 and the early 1980s. A comparison of the CO facility-specific model predictions with CO air concentration measurements from a 1976-1977 survey external to the modeling showed that our model predictions were slightly lower than those observed (median relative difference of 29%; range across facilities: 49 to -25%). In summary, we successfully modeled past CO concentration levels using selected determinants of DE exposure to derive retrospective estimates of REC exposure. The results suggested large variations in REC exposure levels both between and within the underground operations of the facilities and over time. These REC exposure estimates were in a plausible range and were used in the investigation of exposure-response relationships in epidemiologic analyses.

Experimental methods for studying microbial survival in extraterrestrial environments.

PubMed

Olsson-Francis, Karen; Cockell, Charles S

2010-01-01

Microorganisms can be used as model systems for studying biological responses to extraterrestrial conditions; however, the methods for studying their response are extremely challenging. Since the first high altitude microbiological experiment in 1935 a large number of facilities have been developed for short- and long-term microbial exposure experiments. Examples are the BIOPAN facility, used for short-term exposure, and the EXPOSE facility aboard the International Space Station, used for long-term exposure. Furthermore, simulation facilities have been developed to conduct microbiological experiments in the laboratory environment. A large number of microorganisms have been used for exposure experiments; these include pure cultures and microbial communities. Analyses of these experiments have involved both culture-dependent and independent methods. This review highlights and discusses the facilities available for microbiology experiments, both in space and in simulation environments. A description of the microorganisms and the techniques used to analyse survival is included. Finally we discuss the implications of microbiological studies for future missions and for space applications. Copyright 2009 Elsevier B.V. All rights reserved.

Task exposures in an office environment: a comparison of methods.

PubMed

Van Eerd, Dwayne; Hogg-Johnson, Sheilah; Mazumder, Anjali; Cole, Donald; Wells, Richard; Moore, Anne

2009-10-01

Task-related factors such as frequency and duration are associated with musculoskeletal disorders in office settings. The primary objective was to compare various task recording methods as measures of exposure in an office workplace. A total of 41 workers from different jobs were recruited from a large urban newspaper (71% female, mean age 41 years SD 9.6). Questionnaire, task diaries, direct observation and video methods were used to record tasks. A common set of task codes was used across methods. Different estimates of task duration, number of tasks and task transitions arose from the different methods. Self-report methods did not consistently result in longer task duration estimates. Methodological issues could explain some of the differences in estimates seen between methods observed. It was concluded that different task recording methods result in different estimates of exposure likely due to different exposure constructs. This work addresses issues of exposure measurement in office environments. It is of relevance to ergonomists/researchers interested in how to best assess the risk of injury among office workers. The paper discusses the trade-offs between precision, accuracy and burden in the collection of computer task-based exposure measures and different underlying constructs captures in each method.

Copper-Based Aquatic Algaecide Adsorption and Accumulation Kinetics: Influence of Exposure Concentration and Duration for Controlling the Cyanobacterium Lyngbya wollei.

PubMed

Bishop, West M; Lynch, Clayton L; Willis, Ben E; Cope, W Gregory

2017-09-01

Filamentous mat-forming cyanobacteria are increasingly impairing uses of freshwater resources. To effectively manage, a better understanding of control measures is needed. Copper (Cu)-based algaecide formulations are often applied to reactively control nuisance cyanobacterial blooms. This laboratory research assessed typical field exposure scenarios for the ability of Cu to partition to, and accumulate in Lyngbya wollei. Exposure factors (Cu concentration × duration) of 4, 8, 16, 24, 32 h were tested across three aqueous Cu concentrations (1, 2, 4 ppm). Results indicated that internally accumulated copper correlated with control of L. wollei, independent of adsorbed copper. L. wollei control was determined by filament viability and chlorophyll a concentrations. Similar exposure factors elicited similar internalized copper levels and consequent responses of L. wollei. Ultimately, a "concentration-exposure-time" (CET) model was created to assist water resource managers in selecting an appropriate treatment regime for a specific in-water infestation. By assessing the exposure concentration and duration required to achieve the internal threshold of copper (i.e., critical burden) that elicits control, water management objectives can be achieved while simultaneously decreasing the environmental loading of copper and potential for non-target species risks.

No evidence of infection or exposure to Highly Pathogenic Avian Influenzas in peridomestic wildlife on an affected poultry facility

USGS Publications Warehouse

Grear, Daniel A.; Dusek, Robert J.; Walsh, Daniel P.; Hall, Jeffrey S.

2017-01-01

We evaluated the potential transmission of avian influenza viruses (AIV) in wildlife species in three settings in association with an outbreak at a poultry facility: 1) small birds and small mammals on a poultry facility that was affected with highly pathogenic AIV (HPAIV) in April 2015; 2) small birds and small mammals on a nearby poultry facility that was unaffected by HPAIV; and 3) small birds, small mammals, and waterfowl in a nearby natural area. We live-captured small birds and small mammals and collected samples from hunter-harvested waterfowl to test for active viral shedding and evidence of exposure (serum antibody) to AIV and the H5N2 HPAIV that affected the poultry facility. We detected no evidence of shedding or specific antibody to AIV in small mammals and small birds 5 mo after depopulation of the poultry. We detected viral shedding and exposure to AIV in waterfowl and estimated approximately 15% viral shedding and 60% antibody prevalence. In waterfowl, we did not detect shedding or exposure to the HPAIV that affected the poultry facility. We also conducted camera trapping around poultry carcass depopulation composting barns and found regular visitation by four species of medium-sized mammals. We provide preliminary data suggesting that peridomestic wildlife were not an important factor in the transmission of AIV during the poultry outbreak, nor did small birds and mammals in natural wetland settings show wide evidence of AIV shedding or exposure, despite the opportunity for exposure.

NO EVIDENCE OF INFECTION OR EXPOSURE TO HIGHLY PATHOGENIC AVIAN INFLUENZAS IN PERIDOMESTIC WILDLIFE ON AN AFFECTED POULTRY FACILITY.

PubMed

Grear, Daniel A; Dusek, Robert J; Walsh, Daniel P; Hall, Jeffrey S

2017-01-01

We evaluated the potential transmission of avian influenza viruses (AIV) in wildlife species in three settings in association with an outbreak at a poultry facility: 1) small birds and small mammals on a poultry facility that was affected with highly pathogenic AIV (HPAIV) in April 2015; 2) small birds and small mammals on a nearby poultry facility that was unaffected by HPAIV; and 3) small birds, small mammals, and waterfowl in a nearby natural area. We live-captured small birds and small mammals and collected samples from hunter-harvested waterfowl to test for active viral shedding and evidence of exposure (serum antibody) to AIV and the H5N2 HPAIV that affected the poultry facility. We detected no evidence of shedding or specific antibody to AIV in small mammals and small birds 5 mo after depopulation of the poultry. We detected viral shedding and exposure to AIV in waterfowl and estimated approximately 15% viral shedding and 60% antibody prevalence. In waterfowl, we did not detect shedding or exposure to the HPAIV that affected the poultry facility. We also conducted camera trapping around poultry carcass depopulation composting barns and found regular visitation by four species of medium-sized mammals. We provide preliminary data suggesting that peridomestic wildlife were not an important factor in the transmission of AIV during the poultry outbreak, nor did small birds and mammals in natural wetland settings show wide evidence of AIV shedding or exposure, despite the opportunity for exposure.

Long Duration Exposure Facility (LDEF) attitude measurements of the interplanetary dust experiment

NASA Technical Reports Server (NTRS)

Kassel, Philip C., Jr.; Singer, S. Fred; Mulholland, J. Derral; Oliver, John P.; Weinberg, Jerry L.; Cooke, William J.; Wortman, Jim J.; Motley, William R., III

1992-01-01

The Long Duration Exposure Facility (LDEF) Interplanetary Dust Experiment (IDE) was unique in providing a time history of impacts of micron-sized particles on six orthogonal faces of LDEF during the first year in orbit. The value of this time resolved data depended on and was enhanced by the proper operation of some basic LDEF systems. Thus, the value of the data is greatly enhanced when the location and orientation of LDEF is known for each time of impact. The location and velocity of LDEF as a function of time can be calculated from the 'two-line elements' published by GSFC during the first year of the LDEF mission. The attitude of LDEF was passively stabilized in a gravity-gradient mode and a magnetically anchored viscous damper was used to dissipate roll, pitch, and yaw motions. Finally, the IDE used a standard LDEF Experiment Power and Data System (EPDS) to collect and store data and also to provide a crystal derived clock pulse (1 count every 13.1072 seconds) for all IDE time measurements. All that remained for the IDE was to provide a system to calibrate the clock, eliminating accumulative errors, and also verify the attitude of LDEF. The IDE used solar cells on six orthogonal faces to observe the LDEF sunrise and provide data about the LDEF attitude. The data was recorded by the EPDS about 10 times per day for the first 345 days of the LDEF mission. This data consist of the number of IDE counts since the last LDEF sunrise and the status of the six solar cells (light or dark) at the time of the last IDE count. The EPDS determined the time that data was recorded and includes, with each record, the master EPDS clock counter (1 count every 1.6384 seconds) that provided the range and resolution for time measurements. The IDE solar cells provided data for an excellent clock calibration, meeting their primary purpose, and the time resolved LDEF attitude measurements that can be gleaned from this data are presented.

The Rise and Fall of Priming: How Visual Exposure Shapes Cortical Representations of Objects

PubMed Central

Zago, Laure; Fenske, Mark J.; Aminoff, Elissa; Bar, Moshe

2006-01-01

How does the amount of time for which we see an object influence the nature and content of its cortical representation? To address this question, we varied the duration of initial exposure to visual objects and then measured functional magnetic resonance imaging (fMRI) signal and behavioral performance during a subsequent repeated presentation of these objects. We report a novel ‘rise-and-fall’ pattern relating exposure duration and the corresponding magnitude of fMRI cortical signal. Compared with novel objects, repeated objects elicited maximal cortical response reduction when initially presented for 250 ms. Counter-intuitively, initially seeing an object for a longer duration significantly reduced the magnitude of this effect. This ‘rise-and-fall’ pattern was also evident for the corresponding behavioral priming. To account for these findings, we propose that the earlier interval of an exposure to a visual stimulus results in a fine-tuning of the cortical response, while additional exposure promotes selection of a subset of key features for continued representation. These two independent mechanisms complement each other in shaping object representations with experience. PMID:15716471

Effects of cycloheximide on extinction in an appetitively motivated operant conditioning task depend on re-exposure duration.

PubMed

Mierzejewski, Pawel; Olczak, Mieszko; Rogowski, Artur; Kostowski, Wojciech; Samochowiec, Jerzy; Filip, Malgorzata; Przegalinski, Edmund; Bienkowski, Przemyslaw

2008-08-29

Little is known about the role of new protein synthesis in extinction of operant responding for natural and chemical reinforcers. In the present study, the authors investigated whether the effects of a protein synthesis inhibitor, cycloheximide (CHX) on extinction of operant responding for sweet reward depended on the duration of re-exposure sessions. In addition, the authors investigated whether the effects of CHX on extinction could generalize to relapse of saccharin seeking induced by discrete cues. CHX injected after short re-exposure sessions (5min) accelerated extinction of non-reinforced responding. In contrast, the drug injected after long re-exposure sessions (30min) partially inhibited extinction. Reinstatement of saccharin seeking induced by the saccharin-paired discrete cues was not altered by the previous treatment with CHX. Concluding, the results of the present study indicate that: (i) the protein synthesis inhibitor, CHX can alter extinction of operant responding for sweet reward in rats; (ii) the effects of CHX on extinction critically depend on the duration of re-exposure/extinction sessions and do not generalize to relapse of saccharin seeking induced by discrete cues.

External Long-Duration Materials Instrument Research Observatory

NASA Astrophysics Data System (ADS)

Engelhardt, J. P.; Heath, K.

2018-02-01

The External Long-duration Materials and Instrument Research Observatory (ELMIRO) is a commercial facility that will allow for continuous and repeatable external testing on the Deep Space Gateway of materials, electronics/instruments for future deep space spacecraft.

Effect of level, duration, and inter-pulse interval of 1-2 kHz sonar signal exposures on harbor porpoise hearing.

PubMed

Kastelein, Ronald A; Hoek, Lean; Gransier, Robin; Rambags, Martijn; Claeys, Naomi

2014-07-01

Safety criteria for underwater low-frequency active sonar sounds produced during naval exercises are needed to protect harbor porpoise hearing. As a first step toward defining criteria, a porpoise was exposed to sequences consisting of series of 1-s, 1-2 kHz sonar down-sweeps without harmonics (as fatiguing noise) at various combinations of average received sound pressure levels (SPLs; 144-179 dB re 1 μPa), exposure durations (1.9-240 min), and duty cycles (5%-100%). Hearing thresholds were determined for a narrow-band frequency-swept sine wave centered at 1.5 kHz before exposure to the fatiguing noise, and at 1-4, 4-8, 8-12, 48, 96, 144, and 1400 min after exposure, to quantify temporary threshold shifts (TTSs) and recovery of hearing. Results show that the inter-pulse interval of the fatiguing noise is an important parameter in determining the magnitude of noise-induced TTS. For the reported range of exposure combinations (duration and SPL), the energy of the exposure (i.e., cumulative sound exposure level; SELcum) can be used to predict the induced TTS, if the inter-pulse interval is known. Exposures with equal SELcum but with different inter-pulse intervals do not result in the same induced TTS.

Respiratory Health - Exposure Measurements and Modeling in the Fragrance and Flavour Industry.

PubMed

Angelini, Eric; Camerini, Gerard; Diop, Malick; Roche, Patrice; Rodi, Thomas; Schippa, Christine; Thomas, Thierry

2016-01-01

Although the flavor and fragrance industry is about 150 years old, the use of synthetic materials started more than 100 years ago, and the awareness of the respiratory hazard presented by some flavoring substances emerged only recently. In 2001, the US National Institute of Occupational Safety and Health (NIOSH) identified for the first time inhalation exposure to flavoring substances in the workplace as a possible occupational hazard. As a consequence, manufacturers must comply with a variety of workplace safety requirements, and management has to ensure the improvement of health and safety of the employees exposed to hazardous volatile organic compounds. In this sensitive context, MANE opened its facilities to an intensive measuring campaign with the objective to better estimate the real level of hazardous respiratory exposure of workers. In this study, exposure to 27 hazardous volatile substances were measured during several types of handling operations (weighing-mixing, packaging, reconditioning-transferring), 430 measurement results were generated, and were exploited to propose an improved model derived from the well-known ECETOC-TRA model. The quantification of volatile substances in the working atmosphere involved three main steps: adsorption of the chemicals on a solid support, thermal desorption, followed by analysis by gas chromatography-mass spectrometry. Our approach was to examine experimental measures done in various manufacturing workplaces and to define correction factors to reflect more accurately working conditions and habits. Four correction factors were adjusted in the ECETOC-TRA to integrate important exposure variation factors: exposure duration, percentage of the substance in the composition, presence of collective protective equipment and wearing of personal protective equipment. Verification of the validity of the model is based on the comparison of the values obtained after adaptation of the ECETOC-TRA model, according to various exposure scenarios, with the experimental values measured under real conditions. After examination of the predicted results, 98% of the values obtained with the proposed new model were above the experimental values measured in real conditions. This must be compared with the results of the classical ECETOC-TRA system, which generates only 37% of overestimated values. As the values generated by the new model intended to help decision-makers of the industry to implement adapted protective action and information, and considering the high variability of the working environments, it was of the utmost importance to us not to underestimate the exposure level. The proposed correction factors have been designed to achieve this goal. We wish to propose the present method as an improved monitoring tool to improve respiratory health and safety in the flavor and fragrance manufacturing facilities.

The reduction of retinal autofluorescence caused by light exposure.

PubMed

Morgan, Jessica I W; Hunter, Jennifer J; Merigan, William H; Williams, David R

2009-12-01

A prior study showed that long exposure to 568-nm light at levels below the maximum permissible exposure safety limit produces retinal damage preceded by a transient reduction in the autofluorescence of retinal pigment epithelial (RPE) cells in vivo. The present study shows how the effects of exposure power and duration combine to produce this autofluorescence reduction and find the minimum exposure causing a detectable autofluorescence reduction. Macaque retinas were imaged using a fluorescence adaptive optics scanning laser ophthalmoscope to resolve individual RPE cells in vivo. The retina was exposed to 568-nm light over a square subtending 0.5 degrees with energies ranging from 1 to 788 J/cm(2), where power and duration were independently varied. In vivo exposures of 5 J/cm(2) and higher caused an immediate decrease in autofluorescence followed by either full autofluorescence recovery (exposures or= 247 J/cm(2)). No significant autofluorescence reduction was observed for exposures of 2 J/cm(2) and lower. Reciprocity of exposure power and duration held for the exposures tested, implying that the total energy delivered to the retina, rather than its distribution in time, determines the amount of autofluorescence reduction. That reciprocity held is consistent with a photochemical origin, which may or may not cause retinal degeneration. The implementation of safe methods for delivering light to the retina requires a better understanding of the mechanism causing autofluorescence reduction. Finally, RPE imaging was demonstrated using light levels that do not cause a detectable reduction in autofluorescence.

The Reduction of Retinal Autofluorescence Caused by Light Exposure

PubMed Central

Morgan, Jessica I. W.; Hunter, Jennifer J.; Merigan, William H.; Williams, David R.

2009-01-01

Purpose We have previously shown that long exposure to 568 nm light at levels below the maximum permissible exposure safety limit produces retinal damage preceded by a transient reduction in the autofluorescence of retinal pigment epithelial (RPE) cells in vivo. Here, we determine how the effects of exposure power and duration combine to produce this autofluorescence reduction and find the minimum exposure causing a detectable autofluorescence reduction. Methods Macaque retinas were imaged using a fluorescence adaptive optics scanning laser ophthalmoscope to resolve individual RPE cells in vivo. The retina was exposed to 568 nm light over a square subtending 0.5° with energies ranging from 1 J/cm2 to 788 J/cm2, where power and duration were independently varied. Results In vivo exposures of 5 J/cm2 and higher caused an immediate decrease in autofluorescence followed by either full autofluorescence recovery (exposures ≤ 210 J/cm2) or permanent RPE cell damage (exposures ≥ 247 J/cm2). No significant autofluorescence reduction was observed for exposures of 2 J/cm2 and lower. Reciprocity of exposure power and duration held for the exposures tested, implying that the total energy delivered to the retina, rather than its distribution in time, determines the amount of autofluorescence reduction. Conclusions That reciprocity holds is consistent with a photochemical origin, which may or may not cause retinal degeneration. The implementation of safe methods for delivering light to the retina requires a better understanding of the mechanism causing autofluorescence reduction. Finally, RPE imaging was demonstrated using light levels that do not cause a detectable reduction in autofluorescence. PMID:19628734

Duration of time on shift before accidental blood or body fluid exposure for housestaff, nurses, and technicians.

PubMed

Green-McKenzie, Judith; Shofer, Frances S

2007-01-01

Shift work has been found to be associated with an increased rate of errors and accidents among healthcare workers (HCWs), but the effect of shift work on accidental blood and body fluid exposure sustained by HCWs has not been well characterized. To determine the duration of time on shift before accidental blood and body fluid exposure in housestaff, nurses, and technicians and the proportion of housestaff who sustain a blood and body fluid exposure after 12 hours on duty. This retrospective, descriptive study was conducted during a 24-month period at a large urban teaching hospital. Participants were HCWs who sustained an accidental blood and body fluid exposure. Housestaff were on duty significantly longer than both nursing staff (P=.02) and technicians (P<.0001) before accidental blood and body fluid exposure. Half of the blood and body fluid exposures sustained by housestaff occurred after being on duty 8 hours or more, and 24% were sustained after being on duty 12 hours or more. Of all HCWs, 3% reported an accidental blood and body fluid exposure, with specific rates of 7.9% among nurses, 9.4% among housestaff, and 3% among phlebotomists. Housestaff were significantly more likely to have longer duration of time on shift before blood and body fluid exposure than were the other groups. Almost one-quarter of accidental blood and body fluid exposures to housestaff were incurred after they had been on duty for 12 hours or more. Housestaff sustained a higher rate of accidental blood and body fluid exposures than did nursing staff and technicians.

Safety of spray-dried powder formulated Pseudomonas fluorescens strain CL145A exposure to subadult/adult unionid mussels during simulated open-water treatments

USGS Publications Warehouse

Luoma, James A.; Weber, Kerry L.; Waller, Diane L.; Wise, Jeremy K.; Mayer, Denise A.; Aloisi, Douglas B.

2015-01-01

After exposure, the mussels were consolidated into wire mesh cages and placed in the Black River for a 27-28 day postexposure period, after which time survival of mussels was assessed. Of the 1,170 mussels tested in the study, 3 were confirmed dead and 5 were not recovered and treated as mortalities in the analysis. The effect and interactions of species, SDP exposure concentration, and SDP exposure duration were analyzed and did not affect mussel survival (p > 0.98). The results from this study indicate that SDP exposure at the maximum approved open-water concentration of 100 mg/L for up to 3 times the maximum approved open-water exposure duration of 8 hours (in other words for 24 hours of exposure) is unlikely to reduce survival of subadult or adult mussels.

Effects of cryogen spray cooling and high radiant exposures on selective vascular injury during laser irradiation of human skin.

PubMed

Tunnell, James W; Chang, David W; Johnston, Carol; Torres, Jorge H; Patrick, Charles W; Miller, Michael J; Thomsen, Sharon L; Anvari, Bahman

2003-06-01

Increasing radiant exposure offers a means to increase treatment efficacy during laser-mediated treatment of vascular lesions, such as port-wine stains; however, excessive radiant exposure decreases selective vascular injury due to increased heat generation within the epidermis and collateral damage to perivascular collagen. To determine if cryogen spray cooling could be used to maintain selective vascular injury (ie, prevent epidermal and perivascular collagen damage) when using high radiant exposures (16-30 J/cm2). Observational study. Academic hospital and research laboratory. Twenty women with normal abdominal skin (skin phototypes I-VI). Skin was irradiated with a pulsed dye laser (wavelength = 585 nm; pulse duration = 1.5 milliseconds; 5-mm-diameter spot) using various radiant exposures (8-30 J/cm2) without and with cryogen spray cooling (50- to 300-millisecond cryogen spurts). Hematoxylin-eosin-stained histologic sections from each irradiated site were examined for the degree of epidermal damage, maximum depth of red blood cell coagulation, and percentage of vessels containing perivascular collagen coagulation. Long cryogen spurt durations (>200 milliseconds) protected the epidermis in light-skinned individuals (skin phototypes I-IV) at the highest radiant exposure (30 J/cm2); however, epidermal protection could not be achieved in dark-skinned individuals (skin phototypes V-VI) even at the lowest radiant exposure (8 J/cm2). The red blood cell coagulation depth increased with increasing radiant exposure (to >2.5 mm for skin phototypes I-IV and to approximately 1.2 mm for skin phototypes V-VI). In addition, long cryogen spurt durations (>200 milliseconds) prevented perivascular collagen coagulation in all skin types. Cryogen spurt durations much longer than those currently used in therapy (>200 milliseconds) may be clinically useful for protecting the epidermis and perivascular tissues when using high radiant exposures during cutaneous laser therapies. Additional studies are necessary to prove clinical safety of these protocols.

Dose-rate effects of ethylene oxide exposure on developmental toxicity.

PubMed

Weller, E; Long, N; Smith, A; Williams, P; Ravi, S; Gill, J; Henessey, R; Skornik, W; Brain, J; Kimmel, C; Kimmel, G; Holmes, L; Ryan, L

1999-08-01

In risk assessment, evaluating a health effect at a duration of exposure that is untested involves assuming that equivalent multiples of concentration (C) and duration (T) of exposure have the same effect. The limitations of this approach (attributed to F. Haber, Zur Geschichte des Gaskrieges [On the history of gas warfare], in Funf Vortrage aus den Jahren 1920-1923 [Five lectures from the years 1920-1923], 1924, Springer, Berlin, pp. 76-92), have been noted in several studies. The study presented in this paper was designed to specifically look at dose-rate (C x T) effects, and it forms an ideal case study to implement statistical models and to examine the statistical issues in risk assessment. Pregnant female C57BL/6J mice were exposed, on gestational day 7, to ethylene oxide (EtO) via inhalation for 1.5, 3, or 6 h at exposures that result in C x T multiples of 2100 or 2700 ppm-h. EtO was selected because of its short half-life, documented developmental toxicity, and relevance to exposures that occur in occupational settings. Concurrent experiments were run with animals exposed to air for similar periods. Statistical analysis using models developed to assess dose-rate effects revealed significant effects with respect to fetal death and resorptions, malformations, crown-to-rump length, and fetal weight. Animals exposed to short, high exposures of EtO on day 7 of gestation were found to have more adverse effects than animals exposed to the same C x T multiple but at longer, lower exposures. The implication for risk assessment is that applying Haber's Law could potentially lead to an underestimation of risk at a shorter duration of exposure and an overestimation of risk at a longer duration of exposure. Further research, toxicological and statistical, are required to understand the mechanism of the dose-rate effects, and how to incorporate the mechanistic information into the risk assessment decision process.

Non-health care facility anticonvulsant medication errors in the United States.

PubMed

DeDonato, Emily A; Spiller, Henry A; Casavant, Marcel J; Chounthirath, Thitphalak; Hodges, Nichole L; Smith, Gary A

2018-06-01

This study provides an epidemiological description of non-health care facility medication errors involving anticonvulsant drugs. A retrospective analysis of National Poison Data System data was conducted on non-health care facility medication errors involving anticonvulsant drugs reported to US Poison Control Centers from 2000 through 2012. During the study period, 108,446 non-health care facility medication errors involving anticonvulsant pharmaceuticals were reported to US Poison Control Centers, averaging 8342 exposures annually. The annual frequency and rate of errors increased significantly over the study period, by 96.6 and 76.7%, respectively. The rate of exposures resulting in health care facility use increased by 83.3% and the rate of exposures resulting in serious medical outcomes increased by 62.3%. In 2012, newer anticonvulsants, including felbamate, gabapentin, lamotrigine, levetiracetam, other anticonvulsants (excluding barbiturates), other types of gamma aminobutyric acid, oxcarbazepine, topiramate, and zonisamide, accounted for 67.1% of all exposures. The rate of non-health care facility anticonvulsant medication errors reported to Poison Control Centers increased during 2000-2012, resulting in more frequent health care facility use and serious medical outcomes. Newer anticonvulsants, although often considered safer and more easily tolerated, were responsible for much of this trend and should still be administered with caution.

INHALATION EXPOSURE-RESPONSE ASSESSMENTS FOR FIVE CHEMICALS

EPA Science Inventory

Inhalation exposure-response assessments for five chemicals (acrolein, ethylene oxide, hexachlorocyclopentadiene, hydrogen sulfide, and phosgene) for less-than-lifetime durations are being developed to inform the development of the Inhalation Exposure-Response Analysis Methodolog...

Repeated Alcohol Extinction Sessions in Conjunction with MK-801, but not Yohimbine or Propranolol, Reduces Subsequent Alcohol Cue-Induced Responding in Rats

PubMed Central

Williams, Keith L.; Harding, Kaitlyn M.

2014-01-01

Cues associated with alcohol can stimulate subjective states that increase relapse. Alcohol-cue associations may be strengthened by enhancing adrenergic activity with yohimbine or weakened by blocking adrenergic activity with propranolol. Alcohol-cue associations may also be weakened by long cue exposure sessions or strengthened by short cue exposure sessions. A useful treatment approach for alcoholism may combine adrenergic manipulation with cue exposure sessions of a specific duration. The present study sought to determine if cue exposure during long- or short-duration extinction sessions with post-session yohimbine or propranolol would alter alcohol cue-induced responding and self-administration. Rats were trained to respond for alcohol during sessions that included an olfactory cue given at the beginning of the session and a visual/auditory cue complex delivered concurrently with alcohol. Cue-induced responding was assessed before and after the repeated extinction sessions. Repeated alcohol extinction sessions of long duration (45 min) or short duration (5 min) were followed immediately by injections of saline, yohimbine, or propranolol. After the second set of cue-induced responding tests, reacquisition of operant alcohol self-administration was examined. To determine if the experimental procedures were sensitive to memory manipulation through other pharmacological mechanisms, the NMDA receptor antagonist MK-801 was given 20 min prior to long-duration extinction sessions. Both the long- and short-duration extinction sessions decreased cue-induced responding. Neither yohimbine nor propranolol, given post-session, had subsequent effects on cue-induced responding or alcohol self-administration. MK-801 blocked the effect of extinction sessions on cue-induced responding but had no effect on self-administration. The present study shows that manipulation of the NMDA system in combination with alcohol cue exposure therapy during extinction-like sessions may be more effective than manipulation of the adrenergic system in reducing the strength of alcohol-cue associations in this specific model of alcohol relapse. PMID:24269546

Airborne Exposures to Polycyclic Aromatic Compounds Among Workers in Asphalt Roofing Manufacturing Facilities.

PubMed

Trumbore, David C; Osborn, Linda V; Johnson, Kathleen A; Fayerweather, William E

2015-01-01

We studied exposure of 151 workers to polycyclic aromatic compounds and asphalt emissions during the manufacturing of asphalt roofing products-including 64 workers from 10 asphalt plants producing oxidized, straight-run, cutback, and wax- or polymer-modified asphalts, and 87 workers from 11 roofing plants producing asphalt shingles and granulated roll roofing. The facilities were located throughout the United States and used asphalt from many refiners and crude oils. This article helps fill a gap in exposure data for asphalt roofing manufacturing workers by using a fluorescence technique that targets biologically active 4-6 ring polycyclic aromatic compounds and is strongly correlated with carcinogenic activity in animal studies. Worker exposures to polycyclic aromatic compounds were compared between manufacturing plants, at different temperatures and using different raw materials, and to important external benchmarks. High levels of fine limestone particulate in the plant air during roofing manufacturing increased polycyclic aromatic compound exposure, resulting in the hypothesis that the particulate brought adsorbed polycyclic aromatic compounds to the worker breathing zone. Elevated asphalt temperatures increased exposures during the pouring of asphalt. Co-exposures in these workplaces which act as confounders for both the measurement of total organic matter and fluorescence were detected and their influence discussed. Exposures to polycyclic aromatic compounds in asphalt roofing manufacturing facilities were lower than or similar to those reported in hot-mix paving application studies, and much below those reported in studies of hot application of built-up roofing asphalt. These relatively low exposures in manufacturing are primarily attributed to air emission controls in the facilities, and the relatively moderate temperatures, compared to built-up roofing, used in these facilities for oxidized asphalt. The exposure to polycyclic aromatic compounds was a very small part of the overall worker exposure to asphalt fume, on average less than 0.07% of the benzene-soluble fraction. Measurements of benzene-soluble fraction were uniformly below the American Conference of Governmental Industrial Hygienists' Threshold Limit Value for asphalt fume.

NASA's Advanced Life Support Systems Human-Rated Test Facility

NASA Technical Reports Server (NTRS)

Henninger, D. L.; Tri, T. O.; Packham, N. J.

1996-01-01

Future NASA missions to explore the solar system will be long-duration missions, requiring human life support systems which must operate with very high reliability over long periods of time. Such systems must be highly regenerative, requiring minimum resupply, to enable the crews to be largely self-sufficient. These regenerative life support systems will use a combination of higher plants, microorganisms, and physicochemical processes to recycle air and water, produce food, and process wastes. A key step in the development of these systems is establishment of a human-rated test facility specifically tailored to evaluation of closed, regenerative life supports systems--one in which long-duration, large-scale testing involving human test crews can be performed. Construction of such a facility, the Advanced Life Support Program's (ALS) Human-Rated Test Facility (HRTF), has begun at NASA's Johnson Space Center, and definition of systems and development of initial outfitting concepts for the facility are underway. This paper will provide an overview of the HRTF project plan, an explanation of baseline configurations, and descriptive illustrations of facility outfitting concepts.

Molecular films associated with LDEF

NASA Technical Reports Server (NTRS)

Crutcher, E. R.; Warner, K. J.

1992-01-01

The molecular films deposited on the surface of the Long Duration Exposure Facility (LDEF) originated from the paints and room-temperature-vulcanized (RTV) silicone materials intentionally used on the satellite and not from residual contaminants. The high silicone content of most of the films and the uniformity of the films indicates a homogenization process in the molecular deposition and suggests a chemically most favored composition for the final film. The deposition on interior surfaces and vents indicated multiple bounce trajectories or repeated deposition-reemission cycles. Exterior surface deposits indicated a significant return flux. Ultraviolet light exposure was required to fix the deposited film as is indicated by the distribution of the films on interior surfaces and the thickness of films at the vent locations. Thermal conditions at the time of exposure to ultraviolet light seems to be an important factor in the thickness of the deposit. Sunrise facing (ram direction) surfaces always had the thicker film. These were the coldest surfaces at the time of their exposure to ultraviolet light. The films have a layered structure suggesting cyclic deposition. As many as 34 distinct layers were seen in the films. The cyclic nature of the deposition and the chemical uniformity of the film one layer to the next suggest an early deposition of the films though there is evidence for the deposition of molecular films throughout the nearly six year exposure of the satellite. A final 'spray' of an organic material associated with water soluble salts occurred very late in the mission. This may have been the result of one of the shuttle dump activities.

Spectral sensitivity of the circadian system

NASA Astrophysics Data System (ADS)

Figueiro, Mariana G.; Bullough, John D.; Rea, Mark S.

2004-01-01

Light exposure regulates several circadian functions in normal humans including the sleep-wake cycle. Individuals with Alzheimer"s Disease (AD) often do not have regular patterns of activity and rest, but, rather, experience random periods of sleep and agitation during both day and night. Bright light during the day and darkness at night has been shown to consolidate activity periods during the day and rest periods at night in AD patients. The important characteristics of bright light exposure (quantity, spectrum, distribution, timing and duration) for achieving these results in AD patients is not yet understood. Recent research has shown that moderate (~18 lx at the cornea) blue (~470 nm) light is effective at suppressing melatonin in normal humans. It was hypothesized that blue light applied just before AD patients retire to their beds for the night would have a measurable impact on their behavior. A pilot study was conducted for 30 days in a senior health care facility using four individuals diagnosed with mild to moderate levels of dementia. Four AD patients were exposed to arrays of blue light from light emitting diodes (max wavelength = 470 nm) in two-hour sessions (18:00 to 20:00 hours) for 10 days. As a control, they were exposed to red light (max wavelength = 640 nm) in two-hour sessions for 10 days prior to the blue light exposure. Despite the modest sample size, exposure to blue LEDs has shown to affect sleep quality and median body temperature peak of these AD patients. Median body temperature peak was delayed by approximately 2 hours after exposure to blue LEDs compared to exposure to red LEDs and sleep quality was improved. This pilot study demonstrated that light, especially LEDs, can be an important contribution to helping AD patients regulate their circadian functions.

Determination of the exposure parameters that maximise the concentrations of the anaesthetic/sedative eugenol in rainbow trout (Oncorhynchus mykiss) skin-on fillet tissue.

PubMed

Meinertz, J R; Porcher, S T; Smerud, J R; Gaikowski, M P

2014-01-01

Studies were conducted to determine the anaesthetic/sedative concentrations and durations that would maximise anaesthetic/sedative residue concentrations in rainbow trout (Oncorhynchus mykiss) skin-on fillet tissue. Rainbow trout (167-404 g) were exposed to 50 mg l(-1) AQUI-S(®) 20E (10% active ingredient, eugenol) in 17°C freshwater for durations up to 1440 min, 100 and 250 mg l(-1) AQUI-S(®) 20E for durations up to 240 min, and 500 and 1000 mg l(-1) AQUI-S(®) 20E for durations up to 90 min. Fish exposed to 100 mg l(-1) AQUI-S(®) 20E for durations of 30, 60, 120 and 240 min had the greatest eugenol concentrations in the fillet tissue, 50, 58, 54 and 62 µg g(-1), respectively. All other exposure concentrations and durations resulted in significantly lower eugenol concentrations, i.e. all < 39 µg g(-1).

Determination of the exposure parameters that maximise the concentrations of the anaesthetic/sedative eugenol in rainbow trout (Oncorhynchus mykiss) skin-on fillet tissue

USGS Publications Warehouse

Meinertz, Jeffery R.; Porcher, Scott T.; Smerud, Justin R.

2014-01-01

Studies were conducted to determine the anaesthetic/sedative concentrations and durations that would maximize anaesthetic/sedative residue concentrations in rainbow trout (Oncorhynchus mykiss) skin-on fillet tissue. Rainbow trout (167–404 g) were exposed to 50 mg l−1 AQUI-S® 20E (10% active ingredient, eugenol) in 17°C freshwater for durations up to 1440 min, 100 and 250 mg l−1 AQUI-S® 20E for durations up to 240 min, and 500 and 1000 mg l−1 AQUI-S® 20E for durations up to 90 min. Fish exposed to 100 mg l−1 AQUI-S® 20E for durations of 30, 60, 120 and 240 min had the greatest eugenol concentrations in the fillet tissue, 50, 58, 54 and 62 µg g−1, respectively. All other exposure concentrations and durations resulted in significantly lower eugenol concentrations, i.e. all −1.

Patterns of discoloration and oxidation by direct and scattered fluxes on LDEF, including oxygen on silicon

NASA Technical Reports Server (NTRS)

Frederickson, A. R.; Filz, R. C.; Rich, F. J.; Sagalyn, P. L.

1992-01-01

A number of interesting discoloration patterns are clearly evident on MOOO2-1 which resides on the three faces of the Long Duration Exposure Facility (LDEF). Most interesting is the pattern of blue oxidation on polished single crystal silicon apparently produced by scattered or direct ram oxygen atoms along the earth face. A complete explanation for the patterns has not yet been obtained. All honeycomb outgassing holes have a small discoloration ring around them that varies in color. The shadow cast by a suspended wire on the earth face surface is not easily explained by either solar photons or by ram flux. The shadows and the dark/light regions cannot be explained consistently by the process of solar ultraviolet paint-darkening modulated by ram flux oxygen bleaching of the paint.

Study of activation data of metal samples from LDEF-1 and Spacelab-2

NASA Technical Reports Server (NTRS)

Laird, C. E.

1994-01-01

Gamma-ray spectra obtained from samples flown aboard the Long Duration Exposure Facility have been analyzed to obtain the nuclear species produced in this material by the interaction of this material with protons and neutrons in this material by the interaction of this material with protons and neutrons encountered in its 69 month orbital flight as well as to quantify the specific activity (pCi/kg) of these nuclear species. This quantification requires accurate corrections of efficiency, self-attenuation, and background. Plans have been developed for archival of the spectra in a form readily accessible to the scientific, engineering and technical community engaged in space research and application. Work has been initiated in the process of estimating the flux of activating particles encountered by material at various locations of the spacecraft.

Coatings could protect composites from hostile space environment

NASA Technical Reports Server (NTRS)

Whitaker, Ann F.

1991-01-01

An experiment has been conducted on about 100 different material/process combinations, most of which were candidates for use in solar arrays having high power-to-weight ratios. These substances were exposed to the LEO environment during Long-Duration Exposure Facility Experiment A0171 in order to evaluate the synergistic effects of the LEO environment on the materials' mechanical, electrical, and optical properties. Materials evaluated include solar cells, cover slips having antireflectance coatings, adhesives, encapsulants, reflective materials, mast and harness materials, structural composites, and thermal control thin films. About one-sixth of the experiment tray was devoted to composite-material tensile specimens, which were specifically to be studied for changes in their mechanical properties. Preliminary results of the surface-damage evaluation are presented. These surface effects are dominated by atomic-oxygen erosion and micrometeoroid/space debris impacts.

The interaction of atomic oxygen with copper: An XPS, AES, XRD, optical transmission, and stylus profilometry study

NASA Technical Reports Server (NTRS)

Raikar, Ganesh N.; Gregory, John C.; Christl, Ligia C.; Peters, Palmer N.

1993-01-01

The University of Alabama in Huntsville (UAH) experiment A-0114 was designed to study the reaction of material surfaces with low earth orbits (LEO) atmospheric oxygen. The experiment contained 128 one-inch circular samples; metals, polymers, carbons, and semiconductors. Half of these samples were exposed on the front of the Long Duration Exposure Facility (LDEF) and remaining on the rear. Among metal samples, copper has shown some interesting new results. There were two forms of copper samples: a thin film sputter-coated on fused silica and a solid piece of OFHC copper. They were characterized by x-ray and Auger electron spectroscopies, x-ray diffraction, and high resolution profilometry. Cu 2p core level spectra were used to demonstrate the presence of Cu2O and CuO and to determine the oxidation states.

Predicted and observed directional dependence of meteoroid/debris impacts on LDEF thermal blankets

NASA Astrophysics Data System (ADS)

Drolshagen, Gerhard

1992-06-01

The number of impacts from meteoroids and space debris particles to the various Long Duration Exposure Facility (LDEF) rows is calculated using ESABASE/DEBRIS, a 3-D numerical analysis tool. It is based on the latest environment flux models and includes geometrical and directional effects. A detailed comparison of model predictions and actual observations is made for impacts on the thermal blankets which covered the USCR experiment. Impact features on these blankets were studied intensively in European laboratories and hypervelocity impacts for calibration were performed. The thermal blankets were located on all LDEF rows, except 3, 9, and 12. Because of their uniform composition and thickness, these blankets allow a direct analysis of the directional dependence of impacts and provide a unique test case for the latest meteoroid and debris flux models.

New meteoroid model predictions for directional impacts on LDEF

NASA Technical Reports Server (NTRS)

Divine, Neil; Aguero, Rene C.

1992-01-01

An extensive body of data, from meteors, zodiacal light, spacecraft-borne impact detectors (helios, Pioneer, Galileo, and Ulysses), and other sources, forms the basis of a new numerical model for the distributions of interplanetary meteoroids. For each of the five populations in this model it is possible to evaluate meteoroid concentration and flux for oriented surfaces or detectors having arbitrary position and velocity in interplanetary space (Divine, 1992, in preparation). For a spacecraft in geocentric orbit, the effects of gravitational focusing and shielding by the Earth were derived with full attention to the directionality of the particles, both on approach (i.e., relative to a massless Earth) and at the target. This modeling approach was exercised to provide an estimate of meteoroid fluence for each of several oriented surfaces on the Long Duration Exposure Facility (LDEF).

Long Duration Exposure Facility mini-data base user`s guide: IBM-compatible PC computer version. (Diskette)

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

Bohnhoff-Hlavacek, G.; Pippin, G.; Dursch, H.

1995-04-01

One of the objectives of the LDEF Special Investigation Group (SIG) was to develop a LDEF data base that identifies the experiment objectives and hardware flown, summarizes results and conclusions, and provides a system analysis overview which would include spacecraft design guidelines and space environmental effects. Compiling this information into an easily accessible data base format and making it available to the space community was a major task accomplished by the System and Materials SIG effort beginning in 1991. Included in this document is a short user`s manual for the LDEF Mini-Data Bases. The user`s manual contains pertinent examples frommore » the data base on specifically how to access and work with the LDEF information. Accompanying this document are the mini-data bases on disk.« less

On-orbit coldwelding

NASA Technical Reports Server (NTRS)

Dursch, Harry; Spear, Steve

1991-01-01

Spacecraft mechanisms are required to operate in the space environment for extended periods of time. A significant concern to the spacecraft designer is the possibility of metal to metal coldwelding or significant increases in friction. Coldwelding can occur between atomically clean metal surfaces when carefully prepared in a vacuum chamber on earth. The question is whether coldwelding occurs in orbit service conditions. The results of the System Special Investigation Group's (SIG's) investigation into whether coldwelding had occurred on any Long Duration Exposure Facility (LDEF) hardware are presented. The results of a literature search into previous ground based anomalies is also presented. Results show that even though there have been no documented on-orbit coldwelding related failures, precautions should be taken to ensure that coldwelding does not occur in the space environment and that seizure does not occur in the prelaunch or launch environment.

Organic solvent exposure and depressive symptoms among licensed pesticide applicators in the Agricultural Health Study

PubMed Central

Siegel, Miriam; Starks, Sarah E.; Sanderson, Wayne T.; Kamel, Freya; Hoppin, Jane A.; Gerr, Fred

2017-01-01

Purpose Although organic solvents are often used in agricultural operations, neurotoxic effects of solvent exposure have not been extensively studied among famers. The current analysis examined associations between questionnaire-based metrics of organic solvent exposure and depressive symptoms among farmers. Methods Results from 692 male Agricultural Health Study participants were analyzed. Solvent type and exposure duration were assessed by questionnaire. An “ever-use” variable and years of use categories were constructed for exposure to gasoline, paint/lacquer thinner, petroleum distillates, and any solvent. Depressive symptoms were ascertained with the Center for Epidemiologic Studies Depression Scale (CES-D); scores were analyzed separately as continuous (0-60) and dichotomous (<16 versus ≥16) variables. Multivariate linear and logistic regression models were used to estimate crude and adjusted associations between measures of solvent exposure and CES-D score. Results Forty-one percent of the sample reported some solvent exposure. The mean CES-D score was 6.5 (SD=6.4; median=5; range=0 – 44); 92% of the sample had a score below 16. After adjusting for covariates, statistically significant associations were observed between ever-use of any solvent, long duration of any solvent exposure, ever-use of gasoline, ever-use of petroleum distillates, and short duration of petroleum distillate exposure and continuous CES-D score (p<0.05). Although nearly all associations were positive, fewer statistically significant associations were observed between metrics of solvent exposure and the dichotomized CES-D variable. Conclusions Solvent exposures were associated with depressive symptoms among farmers. Efforts to limit exposure to organic solvents may reduce the risk of depressive symptoms among farmers. PMID:28702848

Extensive but not Limited Repeated Trials in Passive Avoidance Task Induce Stress-like Symptoms and Affect Memory Function in Rats.

PubMed

Tabassum, Saiqa; Haider, Saida

2018-02-10

Stressful and emotionally arousing experiences are remembered, and previous reports show that repeated exposure to stressful condition enhances emotional learning. However, the usefulness of the repeated exposure depends on the intensity and duration. Although repeated training as a strategy to improve memory performance is receiving increased attention from researchers, repeated training may induce stressful effects that have not yet been considered. The present study investigated whether exposure to repetitive learning trials with limited or extensive durations in a passive avoidance task (PAT) would be beneficial or harmful to emotional memory performance in rats. Rats were exposed to repetitive learning trials for two different durations in the limited exposure (exposure to four repetitive trials) and extensive exposure groups (exposure to 16 repetitive trials) in a single day to compare the impact of both conditions on rat emotional memory performance. Alterations in corticosterone content and associated oxidative and neurochemical systems were assessed to explore the underlying mechanism responsible for changes in emotional memory. Following extensive exposure, a negative impact on emotional memory was observed compared with the limited exposure group. A lack of any further improvement in memory function following extensive training exposure was supported by increased corticosterone levels, decreased 5-hydroxytryptamine (5-HT) levels and abnormal oxidative stress levels, which may induce negative effects on memory consolidation. It is suggested that limited exposure to repetitive learning trials is more useful for studying improvement in emotional memory, whereas extensive exposure may produce chronic stress-like condition that can be detrimental and responsible for compromised memory performance. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Evaluation of the use of oseltamivir prophylaxis in the control of influenza outbreaks in long-term care facilities in Alberta, Canada: a retrospective provincial database analysis

PubMed Central

Ye, Ming; Jacobs, Angela; Khan, Muhammad Naeem; Jaipaul, Joy; Oda, Joanna; Johnson, Marcia; Doroshenko, Alexander

2016-01-01

Objectives To evaluate the impact of oseltamivir prophylaxis in the management and control of influenza outbreaks in long-term care facilities in Alberta, Canada. Setting and participants Long-term care facilities where 127 influenza outbreaks were reported to public health authorities in Alberta, Canada, during two influenza seasons from 2013 to 2015. Design and outcome measures Using routinely collected surveillance and administrative data, we examined the association between decision-making time for oseltamivir recommendation as prophylaxis strategy for influenza outbreaks in long-term care facilities (explanatory variable) and the duration of an influenza outbreak, the postprophylaxis risk of influenza-like illness and hospitalisation among residents of long-term care facilities in Alberta (outcome variables) using multivariable linear and Poisson regression models. Results Oseltamivir prophylaxis decision-making time was positively associated with the postintervention duration of an outbreak, with a 1-day delay in making decision on oseltamivir prophylaxis associated with 2.22 (95% CI 1.37 to 3.06) more days of the duration of an outbreak after controlling for potential confounding effect of the number of residents at risk at intervention, outbreak progression time, prevalence of influenza-like illness during outbreak progression, facility location, presence of mixed strain and based on optimal timing of oseltamivir prophylaxis. Although not statistically significant, a 1-day delay in making decision on oseltamivir prophylaxis was associated with a 5% (95% CI −1% to 11%) increase in the postintervention risk of influenza-like illness, and a 6% (95% CI −8% to 22%) increase in the postintervention risk of hospitalisation after controlling for the same potential confounders. Conclusions Our study demonstrated benefits of using oseltamivir prophylaxis to shorten the duration of influenza outbreaks; however, there were no significant differences in the influenza-like illness and hospitalisation risk occurring after the intervention. Surveillance data may offer means of rapid evaluation of oseltamivir prophylaxis in long-term care facilities as a public health measure. PMID:27381211

Evaluation of the use of oseltamivir prophylaxis in the control of influenza outbreaks in long-term care facilities in Alberta, Canada: a retrospective provincial database analysis.

PubMed

Ye, Ming; Jacobs, Angela; Khan, Muhammad Naeem; Jaipaul, Joy; Oda, Joanna; Johnson, Marcia; Doroshenko, Alexander

2016-07-05

To evaluate the impact of oseltamivir prophylaxis in the management and control of influenza outbreaks in long-term care facilities in Alberta, Canada. Long-term care facilities where 127 influenza outbreaks were reported to public health authorities in Alberta, Canada, during two influenza seasons from 2013 to 2015. Using routinely collected surveillance and administrative data, we examined the association between decision-making time for oseltamivir recommendation as prophylaxis strategy for influenza outbreaks in long-term care facilities (explanatory variable) and the duration of an influenza outbreak, the postprophylaxis risk of influenza-like illness and hospitalisation among residents of long-term care facilities in Alberta (outcome variables) using multivariable linear and Poisson regression models. Oseltamivir prophylaxis decision-making time was positively associated with the postintervention duration of an outbreak, with a 1-day delay in making decision on oseltamivir prophylaxis associated with 2.22 (95% CI 1.37 to 3.06) more days of the duration of an outbreak after controlling for potential confounding effect of the number of residents at risk at intervention, outbreak progression time, prevalence of influenza-like illness during outbreak progression, facility location, presence of mixed strain and based on optimal timing of oseltamivir prophylaxis. Although not statistically significant, a 1-day delay in making decision on oseltamivir prophylaxis was associated with a 5% (95% CI -1% to 11%) increase in the postintervention risk of influenza-like illness, and a 6% (95% CI -8% to 22%) increase in the postintervention risk of hospitalisation after controlling for the same potential confounders. Our study demonstrated benefits of using oseltamivir prophylaxis to shorten the duration of influenza outbreaks; however, there were no significant differences in the influenza-like illness and hospitalisation risk occurring after the intervention. Surveillance data may offer means of rapid evaluation of oseltamivir prophylaxis in long-term care facilities as a public health measure. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Ionizing radiation exposure of LDEF (pre-recovery estimates)

NASA Technical Reports Server (NTRS)

Benton, E. V.; Heinrich, W.; Parnell, T. A.; Armstrong, T. W.; Derrickson, J. H.; Fishman, G. J.; Frank, A. L.; Watts, J. W. Jr; Wiegel, B.

1992-01-01

The long duration exposure facility (LDEF), launched into a 258 nautical mile orbit with an inclination of 28.5 degrees, remained in space for nearly 6 yr. The 21,500 lb NASA satellite was one of the largest payloads ever deployed by the Space Shuttle. LDEF completed 32,422 orbits and carried 57 major experiments representing more than 200 investigators from 33 private companies, 21 universities and nine countries. The experiments covered a wide range of disciplines including basic science, electronics, optics, materials, structures and power and propulsion. A number of the experiments were specifically designed to measure the radiation environment. These experiments are of specific interest, since the LDEF orbit is essentially the same as that of the Space Station Freedom. Consequently, the radiation measurements on LDEF will play a significant role in the design of radiation shielding of the space station. The contributions of the various authors presented here attempt to predict the major aspects of the radiation exposure received by the various LDEF experiments and therefore should be helpful to investigators who are in the process of analyzing experiments which may have been affected by exposure to ionizing radiation. The paper discusses the various types and sources of ionizing radiation including cosmic rays, trapped particles (both protons and electrons) and secondary particles (including neutrons, spallation products and high-LET recoils), as well as doses and LET spectra as a function of shielding. Projections of the induced radioactivity of LDEF are also discussed.

Kiln emissions and potters' exposures.

PubMed

Hirtle, B; Teschke, K; van Netten, C; Brauer, M

1998-10-01

Some ten thousand British Columbia potters work in small private studios, cooperative facilities, educational institutions, or recreation centers. There has been considerable concern that this diffuse, largely unregulated activity may involve exposures to unacceptable levels of kiln emissions. Pottery kiln emissions were measured at 50 sites--10 from each of 5 categories: professional studios, recreation centers, elementary schools, secondary schools, and colleges. Area monitoring was done 76 cm from firing kilns and 1.6 m above the floor to assess breathing zone concentrations of nitrogen dioxide, carbon monoxide, sulfur dioxide, fluorides, aldehydes, aluminum, antimony, arsenic, barium, beryllium, boron, cadmium, chromium, cobalt, copper, gold, iron, lead, lithium, magnesium, manganese, mercury, nickel, selenium, silver, vanadium, and zinc. Personal exposures to the same metals were measured at 24 sites. Almost all measured values were well below permissible concentrations for British Columbia work sites and American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) with the following two exceptions. A single firing duration (495 minute) acrolein measurement adjacent to an electric kiln (0.109 ppm) exceeded these guidelines. One 15-minute sulfur dioxide measurement collected adjacent to a gas kiln (5.7 ppm) exceeded the ACGIH short-term exposure limit. The fact that concentrations in small, ventilated kiln rooms ranked among the highest measured gives rise to concern that unacceptable levels of contamination may exist where small kiln rooms remain unventilated. Custom designed exhaust hoods and industrial heating, ventilating, and air-conditioning systems were the most effective ventilation strategies. Passive diffusion and wall/window fans were least effective.

Second LDEF Post-Retrieval Symposium interim results of experiment A0034

NASA Technical Reports Server (NTRS)

Linton, Roger C.; Kamenetzky, Rachel R.

1993-01-01

Thermal control coatings and contaminant collector mirrors were exposed on the leading and trailing edge modules of Long Duration Exposure Facility (LDEF) experiment A0034 to provide a basis of comparison for investigating the role of atomic oxygen in the stimulation of volatile outgassing products. The exposure of identical thermal coatings on both the leading and trailing edges of the LDEF and the additional modified exposure of identical coatings under glass windows and metallic covers in each of the flight modules provided multiple combinations of space environmental exposure to the coatings and the contaminant collector mirrors. Investigations were made to evaluate the effects of the natural space and the induced environments on the thermal coatings and the collector mirrors to differentiate the sources of observed material degradation. Two identical flight units were fabricated for the LDEF mission, each of which included twenty-five thermal control coatings mounted in isolated compartments, each with an adjacent contaminant collector mirror mounted on the wall. The covers of the flight units included apertures for each compartment, exposing the thermal coatings directly to the space environment. Six of these compartments were sealed with ultraviolet-grade transmitting quartz windows and four other compartments were sealed with aluminum covers. One module of this passive LDEF experiment, occupying one-sixth of a full tray, was mounted in Tray C9 (leading edge), while the other identical module was mounted in Tray C3 (trailing edge).

HUMAN EXPOSURE MODELING: CONCEPTS, METHODS, AND TOOLS

EPA Science Inventory

Understanding human exposure is critical when estimating the occurrence of deleterious effects that could follow contact with environmental contaminants. For many pollutants, the intensity, duration, frequency, route, and timing of exposure is highly variable, particularly whe...

Evaluating the impact of the Baby-Friendly Hospital Initiative on breast-feeding rates: a multi-state analysis

PubMed Central

Hawkins, Summer Sherburne; Stern, Ariel Dora; Baum, Christopher F; Gillman, Matthew W

2014-01-01

Objective To evaluate the impact of the Baby-Friendly Hospital Initiative (BFHI) on breast-feeding initiation and duration overall and according to maternal education. Design Quasi-experimental study using data from five states (Alaska, Maine, Nebraska, Ohio, Washington) that participated in the Pregnancy Risk Assessment Monitoring System from 1999 to 2009. Using differences-in-differences models that included year and hospital fixed effects, we compared rates of breast-feeding initiation and duration (any and exclusive breast-feeding for ≥4 weeks) before and after BFHI accreditation between mothers who gave birth in hospitals that were accredited or became accredited and mothers from matched non-BFHI facilities. We stratified analyses into lower and higher education groups. Setting Thirteen BFHI hospitals and nineteen matched non-BFHI facilities across five states in the USA. Subjects Mothers (n 11723) who gave birth in BFHI hospitals and mothers (n 13604) from nineteen matched non-BFHI facilities. Results Although we did not find overall differences in breast-feeding initiation between birth facilities that received BFHI accreditation compared with non-Baby-Friendly facilities (adjusted coefficient = 0.024; 95 % CI −0.00, 0.51), breast-feeding initiation increased by 3.8 percentage points among mothers with lower education who delivered in Baby-Friendly facilities (P = 0.05), but not among mothers with higher education (adjusted coefficient = 0.002; 95 % CI −0.04, 0.05). BFHI accreditation also increased exclusive breast-feeding for ≥4 weeks by 4.5 percentage points (P=0.02) among mothers with lower education who delivered in BFHI facilities. Conclusions By increasing breast-feeding initiation and duration among mothers with lower education, the BFHI may reduce socio-economic disparities in breast-feeding. PMID:24625787

Evaluating the impact of the Baby-Friendly Hospital Initiative on breast-feeding rates: a multi-state analysis.

PubMed

Hawkins, Summer Sherburne; Stern, Ariel Dora; Baum, Christopher F; Gillman, Matthew W

2015-02-01

To evaluate the impact of the Baby-Friendly Hospital Initiative (BFHI) on breast-feeding initiation and duration overall and according to maternal education. Quasi-experimental study using data from five states (Alaska, Maine, Nebraska, Ohio, Washington) that participated in the Pregnancy Risk Assessment Monitoring System from 1999 to 2009. Using differences-in-differences models that included year and hospital fixed effects, we compared rates of breast-feeding initiation and duration (any and exclusive breast-feeding for ≥4 weeks) before and after BFHI accreditation between mothers who gave birth in hospitals that were accredited or became accredited and mothers from matched non-BFHI facilities. We stratified analyses into lower and higher education groups. Thirteen BFHI hospitals and nineteen matched non-BFHI facilities across five states in the USA. Mothers (n 11 723) who gave birth in BFHI hospitals and mothers (n 13 604) from nineteen matched non-BFHI facilities. Although we did not find overall differences in breast-feeding initiation between birth facilities that received BFHI accreditation compared with non-Baby-Friendly facilities (adjusted coefficient = 0·024; 95 % CI -0·00, 0·51), breast-feeding initiation increased by 3·8 percentage points among mothers with lower education who delivered in Baby-Friendly facilities (P = 0·05), but not among mothers with higher education (adjusted coefficient = 0·002; 95 % CI -0·04, 0·05). BFHI accreditation also increased exclusive breast-feeding for ≥4 weeks by 4·5 percentage points (P = 0·02) among mothers with lower education who delivered in BFHI facilities. By increasing breast-feeding initiation and duration among mothers with lower education, the BFHI may reduce socio-economic disparities in breast-feeding.

a Comparison of Evaluations and Assessments Obtained Using Alternative Standards for Predicting the Hazards of Whole-Body Vibration and Repeated Shocks

NASA Astrophysics Data System (ADS)

Lewis, C. H.; Griffin, M. J.

1998-08-01

There are three current standards that might be used to assess the vibration and shock transmitted by a vehicle seat with respect to possible effects on human health: ISO 2631/1 (1985), BS 6841 (1987) and ISO 2631-1 (1997). Evaluations have been performed on the seat accelerations measured in nine different transport environments (bus, car, mobile crane, fork-lift truck, tank, ambulance, power boat, inflatable boat, mountain bike) in conditions that might be considered severe. For each environment, limiting daily exposure durations were estimated by comparing the frequency weighted root mean square (i.e., r.m.s.) accelerations and the vibration dose values (i.e.,VDV), calculated according to each standard with the relevant exposure limits, action level and health guidance caution zones. Very different estimates of the limiting daily exposure duration can be obtained using the methods described in the three standards. Differences were observed due to variations in the shapes of the frequency weightings, the phase responses of the frequency weighting filters, the method of combining multi-axis vibration, the averaging method, and the assessment method. With the evaluated motions, differences in the shapes of the weighting filters results in up to about 31% difference in r.m.s. acceleration between the “old” and the “new” ISO standard and up to about 14% difference between BS 6841 and the “new” ISO 2631. There were correspondingly greater differences in the estimates of safe daily exposure durations. With three of the more severe motions there was a difference of more than 250% between estimated safe daily exposure durations based on r.m.s. acceleration and those based on fourth power vibration dose values. The vibration dose values provided the more cautious assessments of the limiting daily exposure duration.

The LDCE Particle Impact Experiment as flown on STS-46. [limited duration space environment candidate materials exposure (LDCE)

NASA Technical Reports Server (NTRS)

Maag, Carl R.; Tanner, William G.; Borg, Janet; Bibring, Jean-Pierre; Alexander, W. Merle; Maag, Andrew J.

1992-01-01

Many materials and techniques have been developed by the authors to sample the flux of particles in Low Earth Orbit (LEO). Though regular in-site sampling of the flux in LEO the materials and techniques have produced data which compliment the data now being amassed by the Long Duration Exposure Facility (LDEF) research activities. Orbital debris models have not been able to describe the flux of particles with d sub p less than or = 0.05 cm, because of the lack of data. Even though LDEF will provide a much needed baseline flux measurement, the continuous monitoring of micron and sub-micron size particles must be carried out. A flight experiment was conducted on the Space Shuttle as part of the LDCE payload to develop an understanding of the Spatial Density (concentration) as a function of size (mass) for particle sizes 1 x 10(exp 6) cm and larger. In addition to the enumeration of particle impacts, it is the intent of the experiment that hypervelocity particles be captured and returned intact. Measurements will be performed post flight to determine the flux density, diameters, and subsequent effects on various optical, thermal control and structural materials. In addition to these principal measurements, the Particle Impact Experiment (PIE) also provides a structure and sample holders for the exposure of passive material samples to the space environment, e.g., thermal cycling, and atomic oxygen, etc. The experiment will measure the optical property changes of mirrors and will provide the fluence of the ambient atomic oxygen environment to other payload experimenters. In order to augment the amount of material returned in a form which can be analyzed, the survivability of the experiment as well as the captured particles will be assessed. Using Sandia National Laboratory's hydrodynamic computer code CTH, hypervelocity impacts on the materials which comprise the experiments have been investigated and the progress of these studies are reported.

Patient room lighting influences on sleep, appraisal and mood in hospitalized people.

PubMed

Giménez, Marina C; Geerdinck, Leonie M; Versteylen, Mathijs; Leffers, Pieter; Meekes, Gaby J B M; Herremans, Hannelore; de Ruyter, Boris; Bikker, Jan Willem; Kuijpers, Petra M J C; Schlangen, Luc J M

2017-04-01

Irregular 24 h light/dark cycles with night-time light exposure and a low amplitude are disruptive for sleep, mood and circadian rhythms. Nevertheless such lighting conditions are quite common in medical care facilities. A controlled clinical trial among 196 cardiology ward patients (mean age 66.5 ± 13.1 years SD) investigated how a patient room lighting intervention affects sleep, appraisal and mood across hospitalization. Patients were either assigned to a standardly-lit room or to a room with an interventional lighting system offering a dynamic 24 h light/dark cycle with low nocturnal light exposure and 2 h of bright light (1750 lux) during daytime. Measures included wrist actigraphy and questionnaires assessing alertness, sleep quality, anxiety, depression and lighting appraisal. The median length of hospitalization was 5 days in both study arms. Subjective scores on sleep, alertness, anxiety and depression did not differ between arms. Lighting appraisal in intervention rooms was better as compared to standardly-lit rooms, both in patients (P < 0.001) and staff (P < 0.005). Actigraphic sleep duration of patients improved by 5.9 min (95% CI: 0.6-11.2; P = 0.03 intervention × time effect) per hospitalization day with interventional lighting instead of standard lighting. After 5 days of hospitalization, sleep duration in the lighting intervention rooms increased by 29 min, or a relative 7.3%, as compared to standardly-lit rooms. A 24 h lighting system with enhanced daytime brightness and restricted nocturnal light exposure can improve some aspects of appraisal and objective sleep in hospital patients. More clinical research is needed to establish the best lighting strategy to promote healing and wellbeing within healthcare settings. © 2016 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.

Identification and classification of high risk groups for Coal Workers' Pneumoconiosis using an artificial neural network based on occupational histories: a retrospective cohort study

PubMed Central

Liu, Hongbo; Tang, Zhifeng; Yang, Yongli; Weng, Dong; Sun, Gao; Duan, Zhiwen; Chen, Jie

2009-01-01

Background Coal workers' pneumoconiosis (CWP) is a preventable, but not fully curable occupational lung disease. More and more coal miners are likely to be at risk of developing CWP owing to an increase in coal production and utilization, especially in developing countries. Coal miners with different occupational categories and durations of dust exposure may be at different levels of risk for CWP. It is necessary to identify and classify different levels of risk for CWP in coal miners with different work histories. In this way, we can recommend different intervals for medical examinations according to different levels of risk for CWP. Our findings may provide a basis for further emending the measures of CWP prevention and control. Methods The study was performed using longitudinal retrospective data in the Tiefa Colliery in China. A three-layer artificial neural network with 6 input variables, 15 neurons in the hidden layer, and 1 output neuron was developed in conjunction with coal miners' occupational exposure data. Sensitivity and ROC analyses were adapted to explain the importance of input variables and the performance of the neural network. The occupational characteristics and the probability values predicted were used to categorize coal miners for their levels of risk for CWP. Results The sensitivity analysis showed that influence of the duration of dust exposure and occupational category on CWP was 65% and 67%, respectively. The area under the ROC in 3 sets was 0.981, 0.969, and 0.992. There were 7959 coal miners with a probability value < 0.001. The average duration of dust exposure was 15.35 years. The average duration of ex-dust exposure was 0.69 years. Of the coal miners, 79.27% worked in helping and mining. Most of the coal miners were born after 1950 and were first exposed to dust after 1970. One hundred forty-four coal miners had a probability value ≥0.1. The average durations of dust exposure and ex-dust exposure were 25.70 and 16.30 years, respectively. Most of the coal miners were born before 1950 and began to be exposed to dust before 1980. Of the coal miners, 90.28% worked in tunneling. Conclusion The duration of dust exposure and occupational category were the two most important factors for CWP. Coal miners at different levels of risk for CWP could be classified by the three-layer neural network analysis based on occupational history. PMID:19785771

Experimental short-duration techniques. [gas turbine engine tests

NASA Technical Reports Server (NTRS)

Dunn, Michael G.

1986-01-01

Short-duration facilities used for gas turbine studies are described. Data recording techniques; and instruments (thin-film heat flux gages, high-frequency response pressure measurements, total temperature probes, measurement of rotor tip speed, active measurement of tip clearance) are presented.

The immunotoxicological pattern of subchronic and chronic benzene exposure in rats.

PubMed

Karaulov, Alexander V; Mikhaylova, Irina V; Smolyagin, Alexander I; Boev, Viktor M; Kalogeraki, Alexandra; Tsatsakis, Aristides M; Engin, Ayse Basak

2017-06-05

Exposure to benzene and its inevitable metabolites can result in deleterious effects on human health, including lymphocytopenia, hematotoxicity and cancer. However, the duration of exposure might alter the effects including immune consequences. The aim of this study was to determine whether benzene could modulate lymphocyte proliferation induced by the T cell mitogen concanavalin A, in rats, at different exposure durations. 386 Wistar rats were assigned into control and treatment groups which were subdivided into groups for 45, 90 and 135days for 0,6mL/kg of drinking water mixed benzene treatment. The percentage of CD3+, CD4+, CD8+ spleen lymphocytes was defined using the flow cytometer. Interleukin (IL)-4, IL-6, IL-10 and interferon-gamma, in supernatants of splenocyte cultures stimulated with Concanavalin A, were assessed by enzyme-linked immunosorbent assay (ELISA) technique. The decrease in the total lymphocyte and T cell counts were associated with increased benzene exposure duration. Th2-type cytokine, IL-4 significantly increased, whereas IL-6, CD4+T cells, CD4+/CD8+ ratio and CD3+ T cells decreased. Despite the positive correlation between benzene toxicity and indicated increased immune responses, 45-day exposure to benzene appeared to be the most sensitive time point for evaluating benzene cytotoxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Repeated or long-duration TASER electronic control device exposures: acidemia and lack of respiration.

PubMed

Jauchem, James R

2010-03-01

Conducted energy weapons (CEWs), such as TASER devices, may be applied to subjects in repeated or long-duration modes. Such applications may result in more potentially harmful effects (as reflected in blood factor changes) than shorter exposures. In this review, results from a number of studies of repeated and long-duration CEW exposures in an animal model are examined. Additionally, a few limited investigations of shorter CEW applications to human subjects are considered. Specifically, in anesthetized swine, increased blood acidity (acidemia) and lack of effective respiration were found to be common during or immediately after CEW exposure. The acidemia could have been due to both metabolic and respiratory acidosis. A relatively rapid recovery toward baseline pH levels occurred. The lack of effective respiration has not been verified in experiments of CEW applications to human subjects; however, in some incidents of human deaths after CEW exposures subjects have been reported to stop breathing immediately after the exposure. It is not known if all human subjects exposed to CEW applications in the field (often "on drugs" or "in excited delirium") would be able to maintain adequate breathing. Since a limited number of short CEW applications would be less likely to cause adverse effects, however, CEWs can still be a valuable tool for law enforcement activities.

Perception of care and barriers to treatment in individuals with diabetic retinopathy in India: 11-city 9-state study.

PubMed

Shukla, Rajan; Gudlavalleti, Murthy V S; Bandyopadhyay, Souvik; Anchala, Raghupathy; Gudlavalleti, Aashrai Sai Venkat; Jotheeswaran, A T; Ramachandra, Srikrishna S; Singh, Vivek; Vashist, Praveen; Allagh, Komal; Ballabh, Hira Pant; Gilbert, Clare E

2016-04-01

Diabetic retinopathy is a leading cause of visual impairment. Low awareness about the disease and inequitable distribution of care are major challenges in India. Assess perception of care and challenges faced in availing care among diabetics. The cross-sectional, hospital based survey was conducted in eleven cities. In each city, public and private providers of eye-care were identified. Both multispecialty and standalone facilities were included. Specially designed semi-open ended questionnaires were administered to the clients. 376 diabetics were interviewed in the eye clinics, of whom 62.8% (236) were selected from facilities in cities with a population of 7 million or more. The mean duration of known diabetes was 11.1 (±7.7) years. Half the respondents understood the meaning of adequate glycemic control and 45% reported that they had visual loss when they first presented to an eye facility. Facilities in smaller cities and those with higher educational status were found to be statistically significant predictors of self-reported good/adequate control of diabetes. The correct awareness of glycemic control was significantly high among attending privately-funded facilities and higher educational status. Self-monitoring of glycemic status at home was significantly associated with respondents from larger cities, privately-funded facilities, those who were better educated and reported longer duration of diabetes. Duration of diabetes (41%), poor glycemic control (39.4%) and age (20.7%) were identified as the leading causes of DR. The commonest challenges faced were lifestyle/behavior related. The findings have significant implications for the organization of diabetes services in India.

Occupational exposures and lung cancer risk among Minnesota taconite mining workers.

PubMed

Allen, Elizabeth M; Alexander, Bruce H; MacLehose, Richard F; Nelson, Heather H; Ryan, Andrew D; Ramachandran, Gurumurthy; Mandel, Jeffrey H

2015-09-01

To examine the association between employment duration, elongate mineral particle (EMP) exposure, silica exposure and the risk of lung cancer in the taconite mining industry. We conducted a nested case-control study of lung cancer within a cohort of Minnesota taconite iron mining workers employed by any of the mining companies in operation in 1983. Lung cancer cases were identified by vital records and cancer registry data through 2010. Two age-matched controls were selected from risk sets of cohort members alive and lung cancer free at the time of case diagnosis. Calendar time-specific exposure estimates were made for every job and were used to estimate workers' cumulative exposures. ORs and 95% CIs were estimated using conditional logistic regression. We evaluated total lung cancer risk and risk of histological subtype by total work duration and by cumulative EMP, and silica exposure by quartile of the exposure distribution. A total of 1706 cases and 3381 controls were included in the analysis. After adjusting for work in haematite mining, asbestos exposure and sex, the OR for total duration of employment was 0.99 (95% CI 0.96 to 1.01). The ORs for quartile 4 versus 1 of EMP and silica exposure were 0.82 (95% CI 0.57 to 1.19) and 0.97 (95% CI 0.70 to 1.35), respectively. The risk of each histological subtype of lung cancer did not change with increasing exposure. This study suggests that the estimated taconite mining exposures do not increase the risk of developing lung cancer. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Occupational Exposures and Lung Cancer Risk among Minnesota Taconite Mining Workers

PubMed Central

Allen, Elizabeth M; Alexander, Bruce H; MacLehose, Richard F; Nelson, Heather H; Ryan, Andrew D; Ramachandran, Gurumurthy; Mandel, Jeffrey H

2015-01-01

Objective To examine the association between employment duration, elongate mineral particle (EMP) exposure, and silica exposure and the risk of lung cancer in the taconite mining industry. Methods We conducted a nested case control study of lung cancer within a cohort of Minnesota taconite iron mining workers employed by any of the mining companies in operation in 1983. Lung cancer cases were identified by vital records and cancer registry data through 2010. Two age-matched controls were selected from risk sets of cohort members alive and lung cancer free at the time of case diagnosis. Calendar time-specific exposure estimates were made for every job and were used to estimate workers’ cumulative exposures. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression. We evaluated total lung cancer risk and risk of histological subtype by total work duration and by cumulative EMP and silica exposure by quartile of the exposure distribution. Results A total of 1,706 cases and 3,381 controls were included in the analysis. After adjusting for work in hematite mining, asbestos exposure, and sex, the OR for total duration of employment was 0.99 (95% CI: 0.96–1.01). The ORs for quartile 4 versus 1 of EMP and silica exposure were 0.82 (95% CI: 0.57–1.19) and 0.97 (95% CI: 0.70–1.35) respectively. The risk of each histological subtype of lung cancer did not change with increasing exposure. Conclusions This study suggests that the estimated taconite mining exposures do not increase the risk for the development of lung cancer. PMID:25977445

Biochemical effects of lead exposure on battery manufacture workers with reference to blood pressure, calcium metabolism and bone mineral density.

PubMed

Dongre, Nilima N; Suryakar, Adinath N; Patil, Arun J; Hundekari, Indira A; Devarnavadagi, Basavaraj B

2013-01-01

Lead is one of the most widely scattered toxic metals in the environment and used by mankind for over 9,000 years. Lead in the environment may be derived from natural or anthropogenic sources. In humans, lead can cause a wide range of biological effects depending upon the level and duration of exposure. The purpose of this study was to find out the effect of lead exposure on systolic and diastolic blood pressure, serum calcium, ionized calcium, phosphorus, parathyroid hormone and vitamin D and examine the overall effect of all these parameters on the bone mineral density of battery manufacture workers. For this study ninety battery manufacture workers were selected and divided in three groups depending upon duration of lead exposure. Group I-workers with duration of lead exposure 1-5 years, Group II-workers with duration of lead exposure 6-10 years and Group III-workers with duration of lead exposure more than 10 years. Each group consisted of thirty workers. Thirty age matched healthy control subjects were taken for comparison. Demographic, occupational and clinical data were collected by using questionnaire and interview. The venous blood samples were collected from the study groups and normal healthy control group. At the time of blood collection random urine samples were collected in amber coloured bottles. The biochemical parameters were estimated by using standard assay procedures. Statistical analysis of the data was done using independent student't' test for parametric variables. Values were expressed as mean ± standard deviation (SD). P values of 0.05 or less were considered to be statistically significant. The blood lead levels and urinary lead levels of all workers were significantly increased (P < 0.001) in proportion to the duration of lead exposure as compared to controls. Systolic and diastolic blood pressure were significantly raised (P < 0.001) in all three study groups of battery manufacture workers as compared to controls. Serum Calcium, Ionized calcium, phosphorus were significantly decreased (P < 0.001) in all the three study groups. Serum vitamin D levels were lowered (P < 0.01) and serum PTH was increased (P < 0.01) in workers as compared to controls. The results of this study clearly indicate that the absorption of lead is more in these workers which adversely affects blood pressure, disturbs calcium and phosphorus metabolism which further impairs mineralization of bone resulting in decreased bone mineral density observed in these workers. Lead toxicity is still persistent in battery manufacture workers though they are using sophisticated techniques in these industries. There is a need to protect the workers from the health hazards of occupational lead exposure.

Materials, processes, and environmental engineering network

NASA Technical Reports Server (NTRS)

White, Margo M.

1993-01-01

The Materials, Processes, and Environmental Engineering Network (MPEEN) was developed as a central holding facility for materials testing information generated by the Materials and Processes Laboratory. It contains information from other NASA centers and outside agencies, and also includes the NASA Environmental Information System (NEIS) and Failure Analysis Information System (FAIS) data. Environmental replacement materials information is a newly developed focus of MPEEN. This database is the NASA Environmental Information System, NEIS, which is accessible through MPEEN. Environmental concerns are addressed regarding materials identified by the NASA Operational Environment Team, NOET, to be hazardous to the environment. An environmental replacement technology database is contained within NEIS. Environmental concerns about materials are identified by NOET, and control or replacement strategies are formed. This database also contains the usage and performance characteristics of these hazardous materials. In addition to addressing environmental concerns, MPEEN contains one of the largest materials databases in the world. Over 600 users access this network on a daily basis. There is information available on failure analysis, metals and nonmetals testing, materials properties, standard and commercial parts, foreign alloy cross-reference, Long Duration Exposure Facility (LDEF) data, and Materials and Processes Selection List data.

A Review of Solar-Powered Aircraft Flight Activity at the Pacific Missile Range Test Facility, Kauai, Hawaii

NASA Technical Reports Server (NTRS)

Ehernberger, L. J.; Donohue, Casey; Teets, Edward H., Jr.

2004-01-01

A series of solar-powered aircraft have been designed and operated by AeroVironment, Inc. (Monrovia, CA) as a part of National Aeronautics and Space Administration (NASA) objectives to develop energy-efficient high-altitude long-endurance platforms for earth observations and communications applications. Flight operations have been conducted at NASA's Dryden Flight Research Center, Edwards CA and at the U.S. Navy Pacific Missile Range Facility (PMRF) at Barking Sands, Kauai, HI. These aircraft flown at PMRF are named Pathfinder , Pathfinder Plus and Helios . Sizes of these three aircraft range from 560 lb with a 99-ft wingspan to 2300 lb with a 247-ft wingspan. Available payload capacity reaches approximately 200 lb. Pathfinder uses six engines and propellers: Pathfinder Plus 8; and Helios 14. The 2003 Helios fuel cell configurations used 10 engines and propellers. The PMRF was selected as a base of operations because if offers optimal summertime solar exposure, low prevailing wind-speeds on the runway, modest upper-air wind-speeds and the availability of suitable airspace. Between 1997 and 2001, successive altitude records of 71,530 ft, 80,200 ft, and 96,863 ft were established. Flight durations extended to 18 hours.

Modeling the Unites States government's economic cost of noise-induced hearing loss for a military population.

PubMed

Tufts, Jennifer B; Weathersby, Paul K; Rodriguez, Francisco A

2010-05-01

The purpose of this paper is to demonstrate the feasibility and utility of developing economic cost models for noise-induced hearing loss (NIHL). First, we outline an economic model of NIHL for a population of US Navy sailors with an "industrial"-type noise exposure. Next, we describe the effect on NIHL-related cost of varying the two central model inputs--the noise-exposure level and the duration of exposure. Such an analysis can help prioritize promising areas, to which limited resources to reduce NIHL-related costs should be devoted. NIHL-related costs borne by the US government were computed on a yearly basis using a finite element approach that took into account varying levels of susceptibility to NIHL. Predicted hearing thresholds for the population were computed with ANSI S3.44-1996 and then used as the basis for the calculation of NIHL-related costs. Annual and cumulative costs were tracked. Noise-exposure level and duration were systematically varied to determine their effects on the expected lifetime NIHL-related cost of a specific US Navy sailor population. Our nominal noise-exposure case [93 dB(A) for six years] yielded a total expected lifetime cost of US $13,472 per sailor, with plausible lower and upper bounds of US $2,500 and US $26,000. Starting with the nominal case, a decrease of 50% in exposure level or duration would yield cost savings of approximately 23% and 19%, respectively. We concluded that a reduction in noise level would be more somewhat more cost-effective than the same percentage reduction in years of exposure. Our economic cost model can be used to estimate the changes in NIHL-related costs that would result from changes in noise-exposure level and/or duration for a single military population. Although the model is limited at present, suggestions are provided for adapting it to civilian populations.

Infant media exposure and toddler development.

PubMed

Tomopoulos, Suzy; Dreyer, Benard P; Berkule, Samantha; Fierman, Arthur H; Brockmeyer, Carolyn; Mendelsohn, Alan L

2010-12-01

To determine whether duration and content of media exposure in 6-month-old infants are associated with development at age 14 months. Longitudinal analysis of 259 mother-infant dyads participating in a long-term study related to early child development, from November 23, 2005, through January 14, 2008. An urban public hospital. Mothers with low socioeconomic status and their infants. Duration and content of media exposure at age 6 months. Cognitive and language development at age 14 months. Of 259 infants, 249 (96.1%) were exposed to media at age 6 months, with mean (SD) total exposure of 152.7 (124.5) min/d. In unadjusted and adjusted analyses, duration of media exposure at age 6 months was associated with lower cognitive development at age 14 months (unadjusted: r = -0.17, P < .01; adjusted: β = -0.15, P = .02) and lower language development (r = -0.16, P < .01; β = -0.16, P < .01). Of 3 types of content assessed, only 1 (older child/adult-oriented) was associated with lower cognitive and language development at age 14 months. No significant associations were seen with exposure to young child-oriented educational or noneducational content. This study is the first, to our knowledge, to have longitudinally assessed associations between media exposure in infancy and subsequent developmental outcomes in children from families with low socioeconomic status in the United States. Findings provide strong evidence in support of the American Academy of Pediatrics recommendations of no media exposure prior to age 2 years, although further research is needed.

Quantification of lower extremity physical exposures in various combinations of sit/stand time duration associated with sit-stand workstation.

PubMed

Pei, Huining; Yu, Suihuai; Babski-Reeves, Kari; Chu, Jianjie; Qu, Min; Tian, Baozhen; Li, Wenhua

2017-05-16

Sit-stand workstations are available for office work purposes but there is a dearth of quantitative evidence to state benefits for lower limb outcomes while using them. And there are no guidelines on what constitutes appropriate sit/stand time duration. The primary aim of this study has been to compare muscle activity and perceived discomfort in the lower extremity during various combinations of sit/stand time duration associated with a sit-stand workstation separately and to evaluate the effects of the sit-stand workstation on the lower extremity during the text entry task. During the 5 days, all participants completed a 2-h text entry task each day for various sit/stand time duration combinations as follows: 5/25 min, 10/20 min, 15/15 min, 20/10 min, 25/5 min. Lower extremity muscular exposure of 12 male and 13 female participants was collected at 8 sites by surface electromyography and body discomfort was calculated by a questionnaire under those 5 conditions. Results have demonstrated that lower extremity muscle activity has been significantly varied among the 5 sit/stand time duration groups. Perceived level of discomfort (PLD) has not differed significantly for 9 out of 10 body parts. The muscle activity of the thigh region was influenced by sit/stand time duration significantly. Ergonomic exposures of lower extremity when using a sit-stand workstation were increased, particularly during the long time standing posture. Results indicate that body mass index (BMI) and gender were not significant factors in this study. Combination of sit/stand time duration 25/5 min appears to show positive effects on relief of muscle exposure of back of thigh in the shifts of sitting and standing work position. Med Pr 2017;68(3):315-327. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

A PROBABILISTIC POPULATION EXPOSURE MODEL FOR PM10 AND PM 2.5

EPA Science Inventory

A first generation probabilistic population exposure model for Particulate Matter (PM), specifically for predicting PM10, and PM2.5, exposures of an urban, population has been developed. This model is intended to be used to predict exposure (magnitude, frequency, and duration) ...

Newly postulated neurodevelopmental risks of pediatric anesthesia: theories that could rock our world.

PubMed

Hays, Stephen Robert; Deshpande, Jayant K

2013-04-01

General anesthetics can induce apoptotic neurodegeneration and subsequent maladaptive behaviors in animals. Retrospective human studies suggest associations between early anesthetic exposure and subsequent adverse neurodevelopmental outcomes. The relevance of animal data to clinical practice is unclear and to our knowledge the causality underlying observed associations in humans is unknown. We reviewed newly postulated neurodevelopmental risks of pediatric anesthesia and discuss implications for the surgical care of children. We queried the MEDLINE®/PubMed® and EMBASE® databases for citations in English on pediatric anesthetic neurotoxicity with the focus on references from the last decade. Animal studies in rodents and primates demonstrate apoptotic neuropathology and subsequent maladaptive behaviors after exposure to all currently available general anesthetics with the possible exception of α2-adrenergic agonists. Similar adverse pathological and clinical effects occur after untreated pain. Anesthetic neurotoxicity in animals develops only after exposure above threshold doses and durations during a critical neurodevelopmental window of maximal synaptogenesis in the absence of concomitant painful stimuli. Anesthetic exposure outside this window or below threshold doses and durations shows no apparent neurotoxicity, while exposure in the context of concomitant painful stimuli is neuroprotective. Retrospective human studies suggest associations between early anesthetic exposure and subsequent adverse neurodevelopmental outcomes, particularly after multiple exposures. The causality underlying the associations is unknown. Ongoing investigations may clarify the risks associated with current practice. Surgical care of all patients mandates appropriate anesthesia. Neurotoxic doses and the duration of anesthetic exposure in animals may have little relevance to clinical practice, particularly surgical anesthesia for perioperative pain. The causality underlying the observed associations between early anesthetic exposure and subsequent adverse neurodevelopmental outcomes is unknown. Anesthetic exposure may be a marker of increased risk. Especially in young children, procedures requiring general anesthesia should be performed only as necessary and general anesthesia duration should be minimized. Alternatives to general anesthesia and the deferral of elective procedures beyond the first few years of life should be considered, as appropriate. Participation in ongoing efforts should be encouraged to generate further data. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Laser-induced retinal injury thresholds: variation with retinal irradiated area

NASA Astrophysics Data System (ADS)

Lund, David J.; Schulmeister, Karl; Seiser, Bernhard; Edthofer, Florian

2005-04-01

The retinal injury threshold for exposure to a laser source varies as a function of the irradiated area on the retina. Currently accepted guidelines for the safe use of lasers provide that the MPE will increase as the diameter of the irradiated area for retinal diameters between 25 mm and 1700 mm, based on the ED50 data available in the late 1970s. Recent studies by Zuclich and Lund produced data showing that the ED50 for ns-duration exposures at 532 nm and ms duration exposures at 590 nm varied as the square of the diameter of the irradiated area on the retina. This paper will discuss efforts to resolve the disagreement between the new data and the earlier data though an analysis of all accessible data relating the retinal injury threshold to the diameter of the incident beam on the retina and through simulations using computer models of laser-induced injury. The results show that the retinal radiant exposure required to produce retinal injury is a function of both exposure duration and retinal irradiance diameter and that the current guidelines for irradiance diameter dependence do not accurately reflect the variation of the threshold data.

Hearing threshold shifts and recovery after noise exposure in beluga whales, Delphinapterus leucas.

PubMed

Popov, Vladimir V; Supin, Alexander Ya; Rozhnov, Viatcheslav V; Nechaev, Dmitry I; Sysuyeva, Evgenia V; Klishin, Vladimir O; Pletenko, Mikhail G; Tarakanov, Mikhail B

2013-05-01

Temporary threshold shift (TTS) after loud noise exposure was investigated in a male and a female beluga whale (Delphinapterus leucas). The thresholds were evaluated using the evoked-potential technique, which allowed for threshold tracing with a resolution of ~1 min. The fatiguing noise had a 0.5 octave bandwidth, with center frequencies ranging from 11.2 to 90 kHz, a level of 165 dB re. 1 μPa and exposure durations from 1 to 30 min. The effects of the noise were tested at probe frequencies ranging from -0.5 to +1.5 octaves relative to the noise center frequency. The effect was estimated in terms of both immediate (1.5 min) post-exposure TTS and recovery duration. The highest TTS with the longest recovery duration was produced by noises of lower frequencies (11.2 and 22.5 kHz) and appeared at a test frequency of +0.5 octave. At higher noise frequencies (45 and 90 kHz), the TTS decreased. The TTS effect gradually increased with prolonged exposures ranging from 1 to 30 min. There was a considerable TTS difference between the two subjects.

The Association Between Breastfeeding Exposure and Duration, Neuropsychological Deficits, and Psychopathic Personality Traits in Offspring: The Moderating Role of 5HTTLPR.

PubMed

Jackson, Dylan B; Beaver, Kevin M

2016-03-01

A wealth of research has revealed that a shorter duration of breastfeeding during infancy can increase the risk of various maladaptive traits, including neuropsychological deficits. Despite the number of studies that have been conducted on the topic, few studies have explored whether the effects of breastfeeding on neuropsychological functioning and personality features persist into adulthood. Furthermore, very little research to date has examined whether this relationship is moderated by specific indicators of genetic risk. The current study examines the direct and interactive effects of breastfeeding experiences and the serotonin transporter polymorphism (5HTTLPR) on neuropsychological deficits and psychopathic personality traits. Using data from the National Longitudinal study of Adolescent Health, we find that no exposure to breastfeeding and a shorter duration of breastfeeding significantly increase the risk of exhibiting neuropsychological deficits during adolescence and early adulthood as well as psychopathic personality traits during adulthood. The results also reveal a number of gene × environment interactions between 5HTTLPR, breastfeeding exposure and breastfeeding duration in the prediction of neuropsychological deficits, but not in the prediction of psychopathic personality traits.

Effect of vibration duration on human discomfort. [passenger comfort and random vibration

NASA Technical Reports Server (NTRS)

Clevenson, S. A.; Dempsey, T. K.; Leatherwood, J. D.

1978-01-01

The duration effects of random vertical vibration on passenger discomfort were studied in a simulated section of an aircraft cabin configured to seat six persons in tourist-class style. Variables of the study included time of exposure (0.25 min to 60 min) and the rms amplitude of vibration (0.025g to 0.100g). The vibrations had a white noise spectrum with a bandwidth of 10 Hz centered at 5 Hz. Data indicate that the discomfort threshold occurred at an rms vertical acceleration level of 0.027g for all durations of vibration. However, for acceleration levels that exceeded the discomfort threshold, a systematic decrease in discomfort occurred as a function of increasing duration of vibration. For the range of accelerations used, the magnitude of the discomfort decrement was shown to be independent of acceleration level. The results suggest that discomfort from vertical vibration applied in the frequency range at which humans are most sensitive decreases with longer exposure, which is the opposite of the recommendation of the International Standard ISO 2631-1974 (E) Guide for the Evaluation of Human Exposure to Whole-Body Vibration.

BIOLOGICAL IRRADIATION FACILITY

DOEpatents

McCorkle, W.H.; Cern, H.S.

1962-04-24

A facility for irradiating biological specimens with neutrons is described. It includes a reactor wherein the core is off center in a reflector. A high-exposure room is located outside the reactor on the side nearest the core while a low-exposure room is located on the opposite side. Means for converting thermal neutrons to fast neutrons are movably disposed between the reactor core and the high and low-exposure rooms. (AEC)

Weightless Environment Training Facility (WETF) Materials Coating Evaluation, Volume 1

NASA Technical Reports Server (NTRS)

1995-01-01

The Weightless Environment Training Facility Material Coating Evaluation project has included preparing, coating, testing, and evaluating 800 test panels of three differing substrates. Ten selected coating systems were evaluated in six separate exposure environments and subject to three tests for physical properties. Substrate materials were identified, the manner of surface preparation described, and exposure environments defined. Exposure environments included immersion exposure, cyclic exposure, and field exposure. Cyclic exposures, specifically QUV-Weatherometer and the KTA Envirotest were found to be the most agressive of the environments included in the study when all three evaluation criteria are considered. This was found to result primarily from chalking of the coatings under ultraviolet (UV) light exposure. Volumes 2 and 3 hold the 5 appendices to this report.

Migration of Beryllium via Multiple Exposure Pathways among Work Processes in Four Different Facilities

PubMed Central

Armstrong, Jenna L.; Day, Gregory A.; Park, Ji Young; Stefaniak, Aleksandr B.; Stanton, Marcia L.; Deubner, David C.; Kent, Michael S.; Schuler, Christine R.; Virji, M. Abbas

2016-01-01

Inhalation of beryllium is associated with the development of sensitization; however, dermal exposure may also be important. The primary aim of this study was to elucidate relationships among exposure pathways in four different manufacturing and finishing facilities. Secondary aims were to identify jobs with increased levels of beryllium in air, on skin, and on surfaces; identify potential discrepancies in exposure pathways, and determine if these are related to jobs with previously identified risk. Beryllium was measured in air, on cotton gloves, and on work surfaces. Summary statistics were calculated and correlations among all three measurement types were examined at the facility and job level. Exposure ranking strategies were used to identify jobs with higher exposures. The highest air, glove, and surface measurements were observed in beryllium metal production and beryllium oxide ceramics manufacturing jobs that involved hot processes and handling powders. Two finishing and distribution facilities that handle solid alloy products had lower exposures than the primary production facilities, and there were differences observed among jobs. For all facilities combined, strong correlations were found between air-surface (rp ≥ 0.77), glove-surface (rp ≥ 0.76), and air-glove measurements (rp ≥ 0.69). In jobs where higher risk of beryllium sensitization or disease has been reported, exposure levels for all three measurement types were higher than in jobs with lower risk, though they were not the highest. Some jobs with low air concentrations had higher levels of beryllium on glove and surface wipe samples, suggesting a need to further evaluate the causes of the discrepant levels. Although such correlations provide insight on where beryllium is located throughout the workplace, they cannot identify the direction of the pathways between air, surface, or skin. Ranking strategies helped to identify jobs with the highest combined air, glove, and/or surface exposures. All previously identified high-risk jobs had high air concentrations, dermal mass loading, or both, and none had low dermal and air. We have found that both pathways are relevant. PMID:25357184

Description of the supporting factors of final project in Mathematics and Natural Sciences Faculty of Syiah Kuala University with multiple correspondence analysis

NASA Astrophysics Data System (ADS)

Rusyana, Asep; Nurhasanah; Maulizasari

2018-05-01

Syiah Kuala University (Unsyiah) is hoped to have graduates who are qualified for working or creating a field of work. A final project course implementation process must be effective. This research uses data from the evaluation conducted by Mathematics and Natural Sciences Faculty (FMIPA) of Unsyiah. Some of the factors that support the completion of the final project are duration, guidance, the final project seminars, facility, public impact, and quality. This research aims to know the factors that have a relationship with the completion of the final project and identify similarities among variables. The factors that support the completion of the final project at every study program in FMIPA are (1) duration, (2) guidance and (3) facilities. These factors are examined for the correlations by chi-square test. After that, the variables are analyzed with multiple correspondence analysis. Based on the plot of correspondence, the activities of the guidance and facilities in Informatics Study Program are included in the fair category, while the guidance and facilities in the Chemistry are included in the best category. Besides that, students in Physics can finish the final project with the fastest completion duration, while students in Pharmacy finish for the longest time.

Chronic stress effects and their reversibility on the Fallopian tubes and uterus in rats.

PubMed

Divyashree, S; Yajurvedi, H N

2018-01-01

The durational effects of chronic stress on the Fallopian tubes and uterus were studied by exposing rats to stressors in the form of restraint (1h) and forced swimming (15min) daily for 4, 8 or 12 weeks. One group of stressed rats from each time period was then maintained without exposure to stressors for a further 4 weeks to assess their ability to recover from stress. All time periods of stress exposure resulted in decreased weight of the body and Fallopian tubes; however, the relative weight of the uterus and serum concentrations of oestradiol and insulin increased significantly. The antioxidant potential was decreased with increased malondialdehyde concentrations in the Fallopian tubes following all durations of exposure and after 4 and 8 weeks of stress exposure in the uterus. Interestingly, rats stressed for 12 weeks showed an increase in serum testosterone concentration and antioxidant enzyme activities with a decrease in malondialdehyde concentration in the uterus. The antioxidant enzyme activities and malondialdehyde concentration in the Fallopian tubes of all recovery group rats were similar to stressed rats. However, in the uterus these parameters were similar to controls in recovery group rats after 4 weeks or 8 weeks of exposure, but after 12 weeks of stress exposure these parameters did not return to control levels following the recovery period. These results reveal, for the first time, that chronic stress elicits an irreversible decrease in antioxidant defence in the Fallopian tubes irrespective of exposure duration, whereas the uterus develops reversible oxidative stress under short-term exposure but increased antioxidant potential with endometrial proliferation following long-term exposure.

Lung Cancer and Elemental Carbon Exposure in Trucking Industry Workers

PubMed Central

Laden, Francine; Hart, Jaime E.; Davis, Mary E.; Eisen, Ellen A.; Smith, Thomas J.

2012-01-01

Background: Diesel exhaust has been considered to be a probable lung carcinogen based on studies of occupationally exposed workers. Efforts to define lung cancer risk in these studies have been limited in part by lack of quantitative exposure estimates. Objective: We conducted a retrospective cohort study to assess lung cancer mortality risk among U.S. trucking industry workers. Elemental carbon (EC) was used as a surrogate of exposure to engine exhaust from diesel vehicles, traffic, and loading dock operations. Methods: Work records were available for 31,135 male workers employed in the unionized U.S. trucking industry in 1985. A statistical model based on a national exposure assessment was used to estimate historical work-related exposures to EC. Lung cancer mortality was ascertained through the year 2000, and associations with cumulative and average EC were estimated using proportional hazards models. Results: Duration of employment was inversely associated with lung cancer risk consistent with a healthy worker survivor effect and a cohort composed of prevalent hires. After adjusting for employment duration, we noted a suggestion of a linear exposure–response relationship. For each 1,000-µg/m3 months of cumulative EC, based on a 5-year exposure lag, the hazard ratio (HR) was 1.07 [95% confidence interval (CI): 0.99, 1.15] with a similar association for a 10-year exposure lag [HR = 1.09 (95% CI: 0.99, 1.20)]. Average exposure was not associated with relative risk. Conclusions: Lung cancer mortality in trucking industry workers increased in association with cumulative exposure to EC after adjusting for negative confounding by employment duration. PMID:22739103

Pulmonary deposition modeling with airborne fiber exposure data: a study of workers manufacturing refractory ceramic fibers.

PubMed

Lentz, Thomas J; Rice, Carol H; Succop, Paul A; Lockey, James E; Dement, John M; LeMasters, Grace K

2003-04-01

Increasing production of refractory ceramic fiber (RCF), a synthetic vitreous material with industrial applications (e.g., kiln insulation), has created interest in potential respiratory effects of exposure to airborne fibers during manufacturing. An ongoing study of RCF manufacturing workers in the United States has indicated an association between cumulative fiber exposure and pleural plaques. Fiber sizing data, obtained from electron microscopy analyses of 118 air samples collected in three independent studies over a 20-year period (1976-1995), were used with a computer deposition model to estimate pulmonary dose of fibers of specified dimensions for 652 former and current RCF production workers. Separate dose correction factors reflecting differences in fiber dimensions in six uniform job title groups were used with data on airborne fiber concentration and employment duration to calculate cumulative dose estimates for each worker. From review of the literature, critical dimensions (diameter <0.4 microm, length <10 microm) were defined for fibers that may translocate to the parietal pleura. Each of three continuous exposure/dose metrics analyzed in separate logistic regression models was significantly related to plaques, even after adjusting for possible past asbestos exposure: cumulative fiber exposure, chi(2) = 15.2 (p < 0.01); cumulative pulmonary dose (all fibers), chi(2) = 14.6 (p < 0.01); cumulative pulmonary dose (critical dimension fibers), chi(2) = 12.4 (p < 0.01). Odds ratios (ORs) were calculated for levels of each metric. Increasing ORs were statistically significant for the two highest dose levels of critical dimension fibers (level three, OR = 11, 95%CI = [1.4, 98]; level four, OR = 25, 95%CI = [3.2, 190]). Similar associations existed for all metrics after adjustment for possible asbestos exposure. It was concluded that development of pleural plaques follows exposure- and dose-response patterns, and that airborne fibers in RCF manufacturing facilities include those with critical dimensions associated with pleural plaque formation. Analysis of additional air samples may improve estimates of the dose-response relationship.

End-of-Test Performance and Wear Characterization of NASA's Evolutionary Xenon Thruster (NEXT) Long-Duration Test

NASA Technical Reports Server (NTRS)

Shastry, Rohit; Herman, Daniel A.; Soulas, George C.; Patterson, Michael J.

2014-01-01

The NASA's Evolutionary Xenon Thruster (NEXT) program is developing the next-generation solar electric ion propulsion system with significant enhancements beyond the state-of-the-art NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) ion propulsion system to provide future NASA science missions with enhanced capabilities. A Long-Duration Test (LDT) was initiated in June 2005 to validate the thruster service life modeling and to quantify the thruster propellant throughput capability. Testing was recently completed in February 2014, with the thruster accumulating 51,184 hours of operation, processing 918 kg of xenon propellant, and delivering 35.5 MN-s of total impulse.As part of the test termination procedure, a comprehensive performance characterization was performed across the entire NEXT throttle table. This was performed prior to planned repairs of numerous diagnostics that had become inoperable over the course of the test. After completion of these diagnostic repairs in November 2013, a comprehensive end-of-test performance and wear characterization was performed on the test article prior to exposure to atmosphere. These data have confirmed steady thruster performance with minimal degradation as well as mitigation of numerous life limiting mechanisms encountered in the NSTAR design. Component erosion rates compare favorably to pretest predictions based on semi-empirical models used for the thruster service life assessment. Additional data relating to ion beam density profiles, facility backsputter rates, facility backpressure effects on thruster telemetry, and modulation of the neutralizer keeper current are presented as part of the end-of-test characterization. Presently the test article for the NEXT LDT has been exposed to atmosphere and placed within a clean room environment, with post-test disassembly and inspection underway.

Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long

NASA Technical Reports Server (NTRS)

Czeisler, Charles A.; Barger, Laura K.; Wright, Kenneth P., Jr.; Ronda, Joseph

2009-01-01

Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long (Sleep-Long) will examine the effects of spaceflight and ambient light exposure on the sleep-wake cycles of the crew members during long-duration stays on the space station.

Response terminated displays unload selective attention

PubMed Central

Roper, Zachary J. J.; Vecera, Shaun P.

2013-01-01

Perceptual load theory successfully replaced the early vs. late selection debate by appealing to adaptive control over the efficiency of selective attention. Early selection is observed unless perceptual load (p-Load) is sufficiently low to grant attentional “spill-over” to task-irrelevant stimuli. Many studies exploring load theory have used limited display durations that perhaps impose artificial limits on encoding processes. We extended the exposure duration in a classic p-Load task to alleviate temporal encoding demands that may otherwise tax mnemonic consolidation processes. If the load effect arises from perceptual demands alone, then freeing-up available mnemonic resources by extending the exposure duration should have little effect. The results of Experiment 1 falsify this prediction. We observed a reliable flanker effect under high p-Load, response-terminated displays. Next, we orthogonally manipulated exposure duration and task-relevance. Counter-intuitively, we found that the likelihood of observing the flanker effect under high p-Load resides with the duration of the task-relevant array, not the flanker itself. We propose that stimulus and encoding demands interact to produce the load effect. Our account clarifies how task parameters differentially impinge upon cognitive processes to produce attentional “spill-over” by appealing to visual short-term memory as an additional processing bottleneck when stimuli are briefly presented. PMID:24399983

Response terminated displays unload selective attention.

PubMed

Roper, Zachary J J; Vecera, Shaun P

2013-01-01

Perceptual load theory successfully replaced the early vs. late selection debate by appealing to adaptive control over the efficiency of selective attention. Early selection is observed unless perceptual load (p-Load) is sufficiently low to grant attentional "spill-over" to task-irrelevant stimuli. Many studies exploring load theory have used limited display durations that perhaps impose artificial limits on encoding processes. We extended the exposure duration in a classic p-Load task to alleviate temporal encoding demands that may otherwise tax mnemonic consolidation processes. If the load effect arises from perceptual demands alone, then freeing-up available mnemonic resources by extending the exposure duration should have little effect. The results of Experiment 1 falsify this prediction. We observed a reliable flanker effect under high p-Load, response-terminated displays. Next, we orthogonally manipulated exposure duration and task-relevance. Counter-intuitively, we found that the likelihood of observing the flanker effect under high p-Load resides with the duration of the task-relevant array, not the flanker itself. We propose that stimulus and encoding demands interact to produce the load effect. Our account clarifies how task parameters differentially impinge upon cognitive processes to produce attentional "spill-over" by appealing to visual short-term memory as an additional processing bottleneck when stimuli are briefly presented.

Characterization of exposures to workers covered under the U.S. Energy Employees Compensation Act.

PubMed

Neton, James W

2014-02-01

Since the mid-1940s, hundreds of thousands of workers have been engaged in nuclear weapons-related activities for the U.S. Department of Energy (DOE) and its predecessor agencies. In 2000, Congress promulgated the Energy Employees Occupational Illness Compensation Program Act of 2000 (EEOICPA), which provides monetary compensation and medical benefits to certain energy employees who have developed cancer. Under Part B of EEOICPA, the National Institute for Occupational Safety and Health (NIOSH) is required to estimate radiation doses for those workers who have filed a claim, or whose survivors have filed a claim, under Part B of the Act. To date, over 39,000 dose reconstructions have been completed for workers from more than 200 facilities. These reconstructions have included assessment of both internal and external exposure at all major DOE facilities, as well as at a large number of private companies [known as Atomic Weapons Employer (AWE) facilities in the Act] that engaged in contract work for the DOE and its predecessor agencies. To complete these dose reconstructions, NIOSH has captured and reviewed thousands of historical documents related to site operations and worker/workplace monitoring practices at these facilities. Using the data collected and reviewed pursuant to NIOSH's role under EEOICPA, this presentation will characterize historical internal and external exposures received by workers at DOE and AWE facilities. To the extent possible, use will be made of facility specific coworker models to highlight changes in exposure patterns over time. In addition, the effects that these exposures have on compensation rates for workers are discussed.Introduction of Characterization of Exposures to Workers (Video 1:59, http://links.lww.com/HP/A3).

The Influences of Exposure Pattern and Duration on Elimination Kinetics and Exposure Assessment of Tetrachloroethylene in Humans. Yeh-Chung Chien

EPA Pesticide Factsheets

The current investigation was designed and conducted to examine the body kinetic behaviors by means of breath analysis under various exposure conditions to test the validity of using exhaled breath as a biological marker of exposure.

Cancer Risks near Nuclear Facilities: The Importance of Research Design and Explicit Study Hypotheses

PubMed Central

Wing, Steve; Richardson, David B.; Hoffmann, Wolfgang

2011-01-01

Background In April 2010, the U.S. Nuclear Regulatory Commission asked the National Academy of Sciences to update a 1990 study of cancer risks near nuclear facilities. Prior research on this topic has suffered from problems in hypothesis formulation and research design. Objectives We review epidemiologic principles used in studies of generic exposure–response associations and in studies of specific sources of exposure. We then describe logical problems with assumptions, formation of testable hypotheses, and interpretation of evidence in previous research on cancer risks near nuclear facilities. Discussion Advancement of knowledge about cancer risks near nuclear facilities depends on testing specific hypotheses grounded in physical and biological mechanisms of exposure and susceptibility while considering sample size and ability to adequately quantify exposure, ascertain cancer cases, and evaluate plausible confounders. Conclusions Next steps in advancing knowledge about cancer risks near nuclear facilities require studies of childhood cancer incidence, focus on in utero and early childhood exposures, use of specific geographic information, and consideration of pathways for transport and uptake of radionuclides. Studies of cancer mortality among adults, cancers with long latencies, large geographic zones, and populations that reside at large distances from nuclear facilities are better suited for public relations than for scientific purposes. PMID:21147606

Changes in CR-39 proton sensitivity due to prolonged exposure to high vacuums relevant to the National Ignition Facility and OMEGA.

PubMed

Manuel, M J-E; Rosenberg, M J; Sinenian, N; Rinderknecht, H; Zylstra, A B; Séguin, F H; Frenje, J; Li, C K; Petrasso, R D

2011-09-01

When used at facilities like OMEGA and the NIF, CR-39 is exposed to high vacuum environments before and after irradiation by charged particles and neutrons. Using an electrostatic linear accelerator at MIT, studies have been conducted to investigate the effects of high vacuum exposure on the sensitivity of CR-39 to fusion protons in the ~1-9 MeV energy range. High vacuum conditions, of order 10(-5) Torr, experienced by CR-39 samples at these facilities were emulated. It is shown that vacuum exposure times longer than ~16 h before proton irradiation result in a decrease in proton sensitivity, whereas no effect was observed for up to 67 h of vacuum exposure after proton irradiation. CR-39 sensitivity curves are presented for samples with prolonged exposure to high vacuum before and after proton irradiation. © 2011 American Institute of Physics

Fatal chlorine gas exposure at a metal recycling facility: Case report.

PubMed

Harvey, Robert R; Boylstein, Randy; McCullough, Joel; Shumate, Alice; Yeoman, Kristin; Bailey, Rachel L; Cummings, Kristin J

2018-06-01

At least four workers at a metal recycling facility were hospitalized and one died after exposure to chlorine gas when it was accidentally released from an intact, closed-valved cylinder being processed for scrap metal. This unintentional chlorine gas release marks at least the third such incident at a metal recycling facility in the United States since 2010. We describe the fatal case of the worker whose clinical course was consistent with acute respiratory distress syndrome (ARDS) following exposure to high concentrations of chlorine gas. This case report emphasizes the potential risk of chlorine gas exposure to metal recycling workers by accepting and processing intact, closed-valved containers. The metal recycling industry should take steps to increase awareness of this established risk to prevent future chlorine gas releases. Additionally, public health practitioners and clinicians should be aware that metal recycling workers are at risk for chlorine gas exposure. © 2018 Wiley Periodicals, Inc.

SOA does not Reveal the Absolute Time Course of Cognitive Processing in Fast Priming Experiments

PubMed Central

Tzur, Boaz; Frost, Ram

2007-01-01

Applying Bloch's law to visual word recognition research, both exposure duration of the prime and its luminance determine the prime's overall energy, and consequently determine the size of the priming effect. Nevertheless, experimenters using fast-priming paradigms traditionally focus only on the SOA between prime and target to reflect the absolute speed of cognitive processes under investigation. Some of the discrepancies in results regarding the time course of orthographic and phonological activation in word recognition research may be due to this factor. This hypothesis was examined by manipulating parametrically the luminance of the prime and its exposure duration, measuring their joint impact on masked repetition priming. The results show that small and non-significant priming effects can be more than tripled as a result of simply increasing luminance, when SOA is kept constant. Moreover, increased luminance may compensate for briefer exposure duration and vice versa. PMID:18379635

[Modulating effect of weak combined magnetic fields on duration of mealworm beetle Tenebrio molitor metamorphosis stage].

PubMed

Novikov, V V; Sheĭman, I M; Iablokova, E V; Fesenko, E E

2014-01-01

It is shown that an exposure of pupae of the mealworm beetle Tenebrio molitor to the combined static (42 μT) and very weak alternating (250 nT) magnetic fields exerts different influence, depending on the frequency of the alternating magnetic field, on duration of metamorphosis processes in these insects. For instance, an exposure of pupae to weak combined magnetic fields, adjusted to the frequency of ion cyclotron resonance for glutaminic acid (4,4 Hz), stimulates metamorphosis process--a transitional stage from pupae to imago lasts shorter. An inhibiting effect was observed when adjusted to the frequency of ion cyclotron resonance for Ca2 (32,2 Hz). At some frequencies this effect is not seen. For instance, an exposure at a frequency of ion cyclotron resonance for K+ (16,5 Hz) exerts no noticeable effect on the duration of the pupal metamorphosis stage.

Nitrous oxide-related postoperative nausea and vomiting depends on duration of exposure.

PubMed

Peyton, Philip J; Wu, Christine Yx

2014-05-01

Inclusion of nitrous oxide in the gas mixture has been implicated in postoperative nausea and vomiting (PONV) in numerous studies. However, these studies have not examined whether duration of exposure was a significant covariate. This distinction might affect the future place of nitrous oxide in clinical practice. PubMed listed journals reporting trials in which patients randomized to a nitrous oxide or nitrous oxide-free anesthetic for surgery were included, where the incidence of PONV within the first 24 postoperative hours and mean duration of anesthesia was reported. Meta-regression of the log risk ratio for PONV with nitrous oxide (lnRR PONVN2O) versus duration was performed. Twenty-nine studies in 27 articles met the inclusion criteria, randomizing 10,317 patients. There was a significant relationship between lnRR PONVN2O and duration (r = 0.51, P = 0.002). Risk ratio PONV increased 20% per hour of nitrous oxide after 45 min. The number needed to treat to prevent PONV by avoiding nitrous oxide was 128, 23, and 9 where duration was less than 1, 1 to 2, and over 2 h, respectively. The risk ratio for the overall effect of nitrous oxide on PONV was 1.21 (CIs, 1.04-1.40); P = 0.014. This duration-related effect may be via disturbance of methionine and folate metabolism. No clinically significant effect of nitrous oxide on the risk of PONV exists under an hour of exposure. Nitrous oxide-related PONV should not be seen as an impediment to its use in minor or ambulatory surgery.

Sleep duration as a mediator between an alternating day and night shift work schedule and metabolic syndrome among female hospital employees.

PubMed

Korsiak, Jill; Tranmer, Joan; Day, Andrew; Aronson, Kristan J

2018-02-01

The main objective was to determine whether sleep duration on work shifts mediates the relationship between a current alternating day and night shift work schedule and metabolic syndrome among female hospital employees. The secondary objective was to assess whether cumulative lifetime shift work exposure was associated with metabolic syndrome. In this cross-sectional study of 294 female hospital employees, sleep duration was measured with the ActiGraph GT3X+. Shift work status was determined through self-report. Investigation of the total, direct and indirect effects between shift work, sleep duration on work shifts and metabolic syndrome was conducted using regression path analysis. Logistic regression was used to determine the association between cumulative shift work exposure and metabolic syndrome. Shift work is strongly associated with metabolic syndrome (OR Total =2.72, 95% CI 1.38 to 5.36), and the relationship is attenuated when work shift sleep duration is added to the model (OR Direct =1.18, 95% CI 0.49 to 2.89). Sleep duration is an important intermediate between shift work and metabolic syndrome (OR Indirect =2.25, 95% CI 1.27 to 4.26). Cumulative shift work exposure is not associated with metabolic syndrome in this population. Sleep duration mediates the association between a current alternating day-night shift work pattern and metabolic syndrome. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Influence of condensation on heat flux and pressure measurements in a detonation-based short-duration facility

NASA Astrophysics Data System (ADS)

Haase, S.; Olivier, H.

2017-10-01

Detonation-based short-duration facilities provide hot gas with very high stagnation pressures and temperatures. Due to the short testing time, complex and expensive cooling techniques of the facility walls are not needed. Therefore, they are attractive for economical experimental investigations of high-enthalpy flows such as the flow in a rocket engine. However, cold walls can provoke condensation of the hot combustion gas at the walls. This has already been observed in detonation tubes close behind the detonation wave, resulting in a loss of tube performance. A potential influence of condensation at the wall on the experimental results, like wall heat fluxes and static pressures, has not been considered so far. Therefore, in this study the occurrence of condensation and its influence on local heat flux and pressure measurements has been investigated in the nozzle test section of a short-duration rocket-engine simulation facility. This facility provides hot water vapor with stagnation pressures up to 150 bar and stagnation temperatures up to 3800 K. A simple method has been developed to detect liquid water at the wall without direct optical access to the flow. It is shown experimentally and theoretically that condensation has a remarkable influence on local measurement values. The experimental results indicate that for the elimination of these influences the nozzle wall has to be heated to a certain temperature level, which exclusively depends on the local static pressure.

Effects of Long-Term Thermal Exposure on Commercially Pure Titanium Grade 2 Elevated-Temperature Tensile Properties

NASA Technical Reports Server (NTRS)

Ellis, David L.

2012-01-01

Elevated-temperature tensile testing of commercially pure titanium (CP Ti) Grade 2 was conducted for as-received commercially produced sheet and following thermal exposure at 550 and 650 K (531 and 711 F) for times up to 5000 h. The tensile testing revealed some statistical differences between the 11 thermal treatments, but most thermal treatments were statistically equivalent. Previous data from room temperature tensile testing was combined with the new data to allow regression and development of mathematical models relating tensile properties to temperature and thermal exposure. The results indicate that thermal exposure temperature has a very small effect, whereas the thermal exposure duration has no statistically significant effects on the tensile properties. These results indicate that CP Ti Grade 2 will be thermally stable and suitable for long-duration space missions.

Development and Seed Number in Indeterminate Soybean as Affected by Timing and Duration of Exposure to Long Photoperiods after Flowering

PubMed Central

Kantolic, Adriana G.; Slafer, Gustavo A.

2007-01-01

Background and Aims Long photoperiods from flowering to maturity have been found to delay reproductive development in soybean (Glycine max) and to increase the number of seeds per unit land area. This study was aimed to evaluate whether sensitivity to photoperiod after flowering (a) is quantitatively related to the length of exposure to long days and (b) persists throughout the whole pod-setting period. It was also evaluated whether seed number was related to changes in the duration of post-flowering phenophases. Methods Two field experiments were conducted with an indeterminate cultivar of soybean of maturity group V. In expt 1, photoperiods 2 h longer than natural daylength were applied during different numbers of days from the beginning pod stage (R3) onwards, while in expt 2 these photoperiod extensions were imposed during 9 consecutive days starting at different times between R3 and R6 (full seed) stages. Key Results There was a quantitative response of development to the number of cycles with a long photoperiod. The exposure to long photoperiods from R3 to R5 (beginning of seed growth) increased the duration of R3–R6 regardless of the timing of exposure. The stages of development comprised in the R3–R6 phase were delayed by current as well as by previous exposure to long days. A positive relationship was found between seed number and the duration of R3–R6, irrespective of the timing and length of exposure to the long photoperiod. Conclusions Sensitivity to photoperiod remained high during the reproductive period and was highly and positively coupled with the processes of generation of yield. PMID:17452381

Timing and Duration of Drug Exposure Affects Outcomes of a Drug-Nutrient Interaction During Ontogeny.

PubMed

Ling, Binbing; Aziz, Caroline; Wojnarowicz, Chris; Olkowski, Andrew; Alcorn, Jane

2010-10-14

Significant drug-nutrient interactions are possible when drugs and nutrients share the same absorption and disposition mechanisms. During postnatal development, the outcomes of drug-nutrient interactions may change with postnatal age since these processes undergo ontogenesis through the postnatal period. Our study investigated the dependence of a significant drug-nutrient interaction (cefepime-carnitine) on the timing and duration of drug exposure relative to postnatal age. Rat pups were administered cefepime (5 mg/kg) twice daily subcutaneously according to different dosing schedules (postnatal day 1-4, 1-8, 8-11, 8-20, or 1-20). Cefepime significantly reduced serum and heart L-carnitine levels in postnatal day 1-4, 1-8 and 8-11 groups and caused severe degenerative changes in ventricular myocardium in these groups. Cefepime also altered the ontogeny of several key L-carnitine homeostasis pathways. The qualitative and quantitative changes in levels of hepatic γ-butyrobetaine hydroxylase mRNA and activity, hepatic trimethyllysine hydroxlase mRNA, intestinal organic cation/carnitine transporter (Octn) mRNA, and renal Octn2 mRNA depended on when during postnatal development the cefepime exposure occurred and duration of exposure. Despite lower levels of heart L-carnitine in earlier postnatal groups, levels of carnitine palmitoyltransferase mRNA and activity, heart Octn2 mRNA and ATP levels in all treatment groups remained unchanged with cefepime exposure. However, changes in other high energy phosphate substrates were noted and reductions in the phosphocreatine/ATP ratio were found in rat pups with normal serum L-carnitine levels. In summary, our data suggest a significant drug-nutrient transport interaction in developing neonates, the nature of which depends on the timing and duration of exposure relative to postnatal age.

Timing and Duration of Drug Exposure Affects Outcomes of a Drug-Nutrient Interaction During Ontogeny

PubMed Central

Ling, Binbing; Aziz, Caroline; Wojnarowicz, Chris; Olkowski, Andrew; Alcorn, Jane

2010-01-01

Significant drug-nutrient interactions are possible when drugs and nutrients share the same absorption and disposition mechanisms. During postnatal development, the outcomes of drug-nutrient interactions may change with postnatal age since these processes undergo ontogenesis through the postnatal period. Our study investigated the dependence of a significant drug-nutrient interaction (cefepime-carnitine) on the timing and duration of drug exposure relative to postnatal age. Rat pups were administered cefepime (5 mg/kg) twice daily subcutaneously according to different dosing schedules (postnatal day 1-4, 1-8, 8-11, 8-20, or 1-20). Cefepime significantly reduced serum and heart L-carnitine levels in postnatal day 1-4, 1-8 and 8-11 groups and caused severe degenerative changes in ventricular myocardium in these groups. Cefepime also altered the ontogeny of several key L-carnitine homeostasis pathways. The qualitative and quantitative changes in levels of hepatic γ-butyrobetaine hydroxylase mRNA and activity, hepatic trimethyllysine hydroxlase mRNA, intestinal organic cation/carnitine transporter (Octn) mRNA, and renal Octn2 mRNA depended on when during postnatal development the cefepime exposure occurred and duration of exposure. Despite lower levels of heart L-carnitine in earlier postnatal groups, levels of carnitine palmitoyltransferase mRNA and activity, heart Octn2 mRNA and ATP levels in all treatment groups remained unchanged with cefepime exposure. However, changes in other high energy phosphate substrates were noted and reductions in the phosphocreatine/ATP ratio were found in rat pups with normal serum L-carnitine levels. In summary, our data suggest a significant drug-nutrient transport interaction in developing neonates, the nature of which depends on the timing and duration of exposure relative to postnatal age. PMID:27721360

Influence of long-term exposure to simulated acid rain on development, reproduction and acaricide susceptibility of the carmine spider mite, Tetranychus cinnabarinus

PubMed Central

Wang, Jin-Jun; Zhang, Jian-Ping; He, Lin; Zhao, Zhi-Mo

2006-01-01

Development, reproduction and acaricide susceptibility of Tetranychus cinnabarinus (Boisduvals) (Acari: Tetranychidae) were investigated after long-term (about 40 generations) exposure to various levels of acid rain; pH 2.5, 3.0, 4.0, and 5.6. Deionized water (pH 6.8) served as a control. The mites were reared on eggplant leaves at 28°C, 80%RH and a photoperiod of 14:10 (L:D) in the laboratory. The results showed that the duration of the immature stage was significantly affected by acid rain exposure. The shortest duration (8.90 days) was recorded for populations exposed to pH 5.6 acid rain, while the longest duration (9.37 days) occurred after exposure to pH 2.5 acid rain. Compared with the control population, adult longevity was shortened with an increase in acidity. Similarly, the oviposition duration was also shortened by an increase in acidity. Statistically, female fecundity did not differ significantly between pH 5.6, pH 4.0 and control populations, but did differ significantly between the control population and those exposed to pH 2.5 and pH 3.0 acid rain. This suggested that the mite suffered reproductive defects after long-term exposure to acid rain with higher acidity (pH 2.5 and 3.0). The intrinsic rate of increase among different populations was not significantly affected, but the net reproductive rate of populations exposed to pH 2.5 and 3.0 acid rain was significantly less than pH4.0, 5.6, and control populations. Bioassay results showed that after long-term exposure to acid rain, susceptibility of the mites to two acaricides, dichlorvos and fenpropathrin, did not change significantly. PMID:19537978

Distribution of kerosene components in rats following dermal exposure.

PubMed

Tsujino, Y; Hieda, Y; Kimura, K; Eto, H; Yakabe, T; Takayama, K; Dekio, S

2002-08-01

The systemic distribution of kerosene components in blood and tissues was analysed in rats following dermal exposure. Four types of trimethylbenzenes (TMBs) and aliphatic hydrocarbons (AHCs) with carbon numbers 9-16 (C(9)-C(16)) were analysed as major kerosene components by capillary gas chromatography/mass spectrometry (GC/MS). The kerosene components were detected in blood and all tissues after a small piece of cotton soaked with kerosene was applied to the abdominal skin. The amounts of TMBs detected were higher than those of AHCs. Greater increases in TMB levels were found in adipose tissue in an exposure duration-dependent manner. The amounts of TMBs detected were only at trace levels following post-mortem dermal exposure to kerosene. These findings suggest that kerosene components were absorbed percutaneously and distributed to various organs via the blood circulation. Post-mortem or ante-mortem exposure to kerosene could be distinguished when the exposure duration was relatively long. Adipose tissue would seem to be the most useful for estimating the degree of kerosene exposure.

Occupational and environmental exposure to pesticides and cytokine pathways in chronic diseases (Review).

PubMed

Gangemi, Silvia; Gofita, Eliza; Costa, Chiara; Teodoro, Michele; Briguglio, Giusi; Nikitovic, Dragana; Tzanakakis, George; Tsatsakis, Aristides M; Wilks, Martin F; Spandidos, Demetrios A; Fenga, Concettina

2016-10-01

Pesticides can exert numerous effects on human health as a consequence of both environmental and occupational exposures. The available knowledge base suggests that exposure to pesticides may result in detrimental reproductive changes, neurological dysfunction and several chronic disorders, which are defined by slow evolution and long-term duration. Moreover, an ever increasing amount of data have identified an association between exposure to pesticides and the harmful effects on the immune system. The real impact of alterations in humoral cytokine levels on human health, in particular in the case of chronic diseases, is still unclear. To date, studies have suggested that although exposure to pesticides can affect the immune system functionally, the development of immune disorders depends on the dose and duration of exposure to pesticides. However, many of the respective studies exhibit limitations, such as a lack of information on exposure levels, differences in the pesticide administration procedures, difficulty in characterizing a prognostic significance to the weak modifications often observed and the interpretation of obtained results. The main challenge is not just to understand the role of individual pesticides and their combinations, but also to determine the manner and the duration of exposure, as the toxic effects on the immune system cannot be separated from these considerations. There is a clear need for more well‑designed and standardized epidemiological and experimental studies to recognize the exact association between exposure levels and toxic effects and to identify useful biomarkers of exposure. This review focuses on and critically discusses the immunotoxicity of pesticides and the impact of cytokine levels on health, focusing on the development of several chronic diseases.

Occupational and environmental exposure to pesticides and cytokine pathways in chronic diseases (Review)

PubMed Central

Gangemi, Silvia; Gofita, Eliza; Costa, Chiara; Teodoro, Michele; Briguglio, Giusi; Nikitovic, Dragana; Tzanakakis, George; Tsatsakis, Aristides M.; Wilks, Martin F.; Spandidos, Demetrios A.; Fenga, Concettina

2016-01-01

Pesticides can exert numerous effects on human health as a consequence of both environmental and occupational exposures. The available knowledge base suggests that exposure to pesticides may result in detrimental reproductive changes, neurological dysfunction and several chronic disorders, which are defined by slow evolution and long-term duration. Moreover, an ever increasing amount of data have identified an association between exposure to pesticides and the harmful effects on the immune system. The real impact of alterations in humoral cytokine levels on human health, in particular in the case of chronic diseases, is still unclear. To date, studies have suggested that although exposure to pesticides can affect the immune system functionally, the development of immune disorders depends on the dose and duration of exposure to pesticides. However, many of the respective studies exhibit limitations, such as a lack of information on exposure levels, differences in the pesticide administration procedures, difficulty in characterizing a prognostic significance to the weak modifications often observed and the interpretation of obtained results. The main challenge is not just to understand the role of individual pesticides and their combinations, but also to determine the manner and the duration of exposure, as the toxic effects on the immune system cannot be separated from these considerations. There is a clear need for more well-designed and standardized epidemiological and experimental studies to recognize the exact association between exposure levels and toxic effects and to identify useful biomarkers of exposure. This review focuses on and critically discusses the immunotoxicity of pesticides and the impact of cytokine levels on health, focusing on the development of several chronic diseases. PMID:27600395

Preliminary analyses of WL experiment No. 701, space environment effects on operating fiber optic systems

NASA Technical Reports Server (NTRS)

Taylor, E. W.; Berry, J. N.; Sanchez, A. D.; Padden, R. J.; Chapman, S. P.

1992-01-01

A brief overview of the analyses performed to date on WL Experiment-701 is presented. Four active digital fiber optic links were directly exposed to the space environment for a period of 2114 days. The links were situated aboard the Long Duration Exposure Facility (LDEF) with the cabled, single fiber windings atop an experimental tray containing instrumentation for exercising the experiment in orbit. Despite the unplanned and prolonged exposure to trapped and galactic radiation, wide temperature extremes, atomic oxygen interactions, and micro-meteorite and debris impacts, in most instances the optical data links performed well within the experimental limits. Analysis of the recorded orbital data clearly indicates that fiber optic applications in space will meet with success. Ongoing tests and analysis of the experiment at the Phillips Laboratory's Optoelectronics Laboratory will expand this premise, and establish the first known and extensive database of active fiber optic link performance during prolonged space exposure. WL Exp-701 was designed as a feasibility demonstration for fiber optic technology in space applications, and to study the performance of operating fiber systems exposed to space environmental factors such as galactic radiation, and wide temperature cycling. WL Exp-701 is widely acknowledged as a benchmark accomplishment that clearly demonstrates, for the first time, that fiber optic technology can be successfully used in a variety of space applications.

Analysis of selected specimens from the STS-46 Energetic Oxygen Interaction with Materials-3 experiment

NASA Technical Reports Server (NTRS)

Golden, Johnny L.; Bourassa, Roger J.; Dursch, Harry W.; Pippin, H. Gary

1995-01-01

The Energetic Oxygen Interaction with Materials 3 (EOIM-3) experiment was flown on the STS-46 mission, which was launched on 31 Jul. 1992 and returned 8 Aug. 1992. Boeing specimens were located on both the NASA Marshall Space Flight Center (MSFC) tray and the Ballistic Missile Defense Organization (BMDO) tray integrated by the Jet Propulsion Laboratory (JPL). The EOIM-3 pallet was mounted in the Space Shuttle payload bay near the aft bulkhead. During the mission, the atomic oxygen (AO) exposure levels of specimens in these passive sample trays was about 2.3 x 10(exp 20) atoms/sq cm. The specimens also received an estimated 22 equivalent sun hours of solar exposure. In addition, it appears that the EOIM-3 pallet was exposed to a silicone contamination source and many specimens had a thin layer of silicon based deposit on their surfaces after the flight. The specimens on the MSFC tray included seven solid film lubricants, a selection of butyl rubber (B612) and silicone (S383) o-rings, three indirect scatter surfaces, and Silver/Fluorinated Ethylene Propylene (Ag/FEP) and Chemglaze A276 specimens which had previously flown on trailing edge locations of the Long Duration Exposure Facility (LDEF). The specimens on the JPL tray included composites previously flown on LDEF and two indirect scattering surfaces.

Developing Health-Based Pre-Planning Clearance Goals for Airport Remediation Following a Chemical Terrorist Attack: Decision Criteria for Multipathway Exposure Routes

PubMed Central

Watson, Annetta; Dolislager, Fredrick; Hall, Linda; Raber, Ellen; Hauschild, Veronique D.; Love, Adam H.

2011-01-01

In the event of a chemical terrorist attack on a transportation hub, post-event remediation and restoration activities necessary to attain unrestricted facility re-use and re-entry could require hours to multiple days. While timeframes are dependent on numerous variables, a primary controlling factor is the level of pre-planning and decision-making completed prior to chemical release. What follows is the second of a two-part analysis identifying key considerations, critical information and decision criteria to facilitate post-attack and post-decontamination consequence management activities. Decision criteria analysis presented here provides first-time, open-literature documentation of multi-pathway, health-based remediation exposure guidelines for selected toxic industrial compounds, chemical warfare agents, and agent degradation products for pre-planning application in anticipation of a chemical terrorist attack. Guideline values are provided for inhalation and direct ocular vapor exposure routes as well as percutaneous vapor, surface contact, and ingestion. Target populations include various employees as well as transit passengers. This work has been performed as a national case study conducted in partnership with the Los Angeles International Airport and The Bradley International Terminal. All recommended guidelines have been selected for consistency with airport scenario release parameters of a one-time, short-duration, finite airborne release from a single source followed by compound-specific decontamination. PMID:21399674

Asbestos exposure from gaskets during disassembly of a medium duty diesel engine.

PubMed

Liukonen, Larry R; Weir, Francis W

2005-03-01

Diesel engines have historically used asbestos-containing gaskets leading to concerns of fiber release and mechanic exposure. Other published studies regarding asbestos fiber release during gasket removal have reported on short-duration events; were conducted under simulated work conditions; or had other limitations. There are no comprehensive studies relating to diesel engine gaskets under conditions similar to those reported herein, evaluating asbestos fiber release from gaskets during all facets of a complete disassembly and cleaning of a medium duty diesel engine in a busy repair and service shop by a journeyman mechanic. Asbestos content of all gaskets was identified; all disassembly tasks were described and timed; and personal and area air monitoring was conducted for each task. Twenty seven of thirty three gaskets contained chrysotile asbestos in concentrations that ranged from 5 to 70%. All but one air monitoring sample reported results below the limit of reliable detection even though plumes of visible dust were evident during various removal, cleaning, and buffing procedures. The detection limit for airborne asbestos fibers in this investigation was influenced by the presence of other shop dust in the air. Our investigation demonstrates that using shop-standard procedures in an established repair facility, a journeyman mechanic has very little potential for exposure to airborne asbestos fibers during disassembly of an engine, approximately 10% or less than that currently considered to be acceptable by OSHA.