Conversion of fogwater and aerosol organic nitrogen to ammonium, nitrate, and NOx during exposure to simulated sunlight and ozone.

PubMed

Zhang, Qi; Anastasio, Cort

2003-08-15

Although organic nitrogen (ON) compounds are apparently ubiquitous in the troposphere, very little is known about their fate and transformations. As one step in addressing this issue, we have studied the transformations of bulk (uncharacterized) organic nitrogen in fogwaters and aerosol aqueous extracts during exposure to simulated sunlight and O3. Our results show that over the course of several hours of exposure a significant portion of condensed-phase organic nitrogen is transformed into ammonium, nitrite, nitrate, and NOx. For nitrite, there was both photochemical formation and destruction, resulting in a slow net loss. Ammonium and nitrate were formed at initial rates on the order of a few micromolar per hour in the bulk fogwaters, corresponding to formation rates of approximately 10 and 40 ng m(-3) h(-1), respectively, in ambient fog. The average initial formation rate (expressed as ng (m of air)(-3) h(-1)) of NH4+ in the aqueous extracts of fine particles (PM2.5) was approximately one-half of the corresponding fogwater value. Initial formation rates of NOx (i.e., NO + NO2) were equivalent to approximately 2-11 pptv h(-1) in the three fogwaters tested. Although the formation rates of ammonium and nitrate were relatively small as compared to their initial concentrations in fogwaters (approximately 200-2000 microM) and aerosol particles (approximately 400-1500 ng m(-3)), this photochemical mineralization and "renoxification" from condensed-phase organic N is a previously uncharacterized source of inorganic N in the atmosphere. This conversion also represents a new component in the biogeochemical cycle of nitrogen that might have significant influences on atmospheric composition, condensed-phase properties, and the ecological impacts of N deposition.

Lidar cross-sections of soot fractal aggregates: Assessment of equivalent-sphere models

NASA Astrophysics Data System (ADS)

Ceolato, Romain; Gaudfrin, Florian; Pujol, Olivier; Riviere, Nicolas; Berg, Matthew J.; Sorensen, Christopher M.

2018-06-01

This work assesses the ability of equivalent-sphere models to reproduce the optical properties of soot aggregates relevant for lidar remote sensing, i.e. the backscattering and extinction cross sections. Lidar cross-sections are computed with a spectral discrete dipole approximation model over the visible-to-infrared (400-5000 nm) spectrum and compared with equivalent-sphere approximations. It is shown that the equivalent-sphere approximation, applied to fractal aggregates, has a limited ability to calculate such cross-sections well. The approximation should thus be used with caution for the computation of broadband lidar cross-sections, especially backscattering, at small and intermediate wavelengths (e.g. UV to visible).

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

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

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

1997-12-31

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

Road traffic noise abatement scenarios in Gothenburg 2015 - 2035.

PubMed

Ögren, Mikael; Molnár, Peter; Barregard, Lars

2018-07-01

Exposure to high levels of road traffic noise at the most exposed building facade is increasing, both due to urbanization and due to overall traffic increase. This study investigated how different noise reduction measures would influence the noise exposure on a city-wide scale in Gothenburg, a city in Sweden with approximately 550,000 inhabitants. Noise exposure was estimated under several different scenarios for the period 2015-2035, using the standardized Nordic noise prediction method together with traffic flow measurements and population statistics. The scenarios were based on reducing speed limits, reducing traffic flows, introducing more electrically powered vehicles and introducing low-noise tires and pavements. The most effective measures were introducing low-noise tires or pavements, which in comparison to business as usual produced between 13% and 29% reduction in the number of inhabitants exposed above 55 dB equivalent level. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Comparison of Annoyance from Railway Noise and Railway Vibration.

PubMed

Ögren, Mikael; Gidlöf-Gunnarsson, Anita; Smith, Michael; Gustavsson, Sara; Persson Waye, Kerstin

2017-07-19

The aim of this study is to compare vibration exposure to noise exposure from railway traffic in terms of equal annoyance, i.e., to determine when a certain noise level is equally annoying as a corresponding vibration velocity. Based on questionnaire data from the Train Vibration and Noise Effects (TVANE) research project from residential areas exposed to railway noise and vibration, the dose response relationship for annoyance was estimated. By comparing the relationships between exposure and annoyance for areas both with and without significant vibration exposure, the noise levels and vibration velocities that had an equal probability of causing annoyance was determined using logistic regression. The comparison gives a continuous mapping between vibration velocity in the ground and a corresponding noise level at the facade that are equally annoying. For equivalent noise level at the facade compared to maximum weighted vibration velocity in the ground the probability of annoyance is approximately 20% for 59 dB or 0.48 mm/s, and about 40% for 63 dB or 0.98 mm/s.

Optical equivalence of isotropic ensembles of ellipsoidal particles in the Rayleigh-Gans-Debye and anomalous diffraction approximations and its consequences

NASA Astrophysics Data System (ADS)

Paramonov, L. E.

2012-05-01

Light scattering by isotropic ensembles of ellipsoidal particles is considered in the Rayleigh-Gans-Debye approximation. It is proved that randomly oriented ellipsoidal particles are optically equivalent to polydisperse randomly oriented spheroidal particles and polydisperse spherical particles. Density functions of the shape and size distributions for equivalent ensembles of spheroidal and spherical particles are presented. In the anomalous diffraction approximation, equivalent ensembles of particles are shown to also have equal extinction, scattering, and absorption coefficients. Consequences of optical equivalence are considered. The results are illustrated by numerical calculations of the angular dependence of the scattering phase function using the T-matrix method and the Mie theory.

Does the form or the amount of exposure make a difference in the cognitive-behavioral therapy treatment of social phobia?

PubMed

Borgeat, François; Stankovic, Miroslava; Khazaal, Yasser; Rouget, Beatrice Weber; Baumann, Marie-Claude; Riquier, Françoise; O'Connor, Kieron; Jermann, Françoise; Zullino, Daniele; Bondolfi, Guido

2009-07-01

Exposure is considered to be an essential ingredient of cognitive-behavioral therapy treatment of social phobia and of most anxiety disorders. To assess the impact of the amount of exposure on outcome, 30 social phobic patients were randomly allocated to 1 of 2 group treatments of 8 weekly sessions: Self-Focused Exposure Therapy which is based essentially on prolonged exposure to public speaking combined with positive feedback or a more standard cognitive and behavioral method encompassing psychoeducation, cognitive work, working through exposure hierarchies of feared situations for exposure within and outside the group. The results show that the 2 methods led to significant and equivalent symptomatic improvements which were maintained at 1-year follow-up. There was a more rapid and initially more pronounced decrease in negative cognitions with the Self-Focused Exposure Therapy, which included no formal cognitive work, than with the more standard approach in which approximately a third of the content was cognitive. In contrast, decrease in social avoidance was more persistent with standard cognitive-behavior therapy which involved less exposure. The results indicate that positive cognitive change can be achieved more rapidly with non cognitive methods while avoidance decreases more reliably with a standard approach rather than an approach with an exclusive focus on exposure.

Exposure to airborne asbestos in thermal power plants in Mongolia

PubMed Central

Damiran, Naransukh; Silbergeld, Ellen K; Frank, Arthur L; Lkhasuren, Oyuntogos; Ochir, Chimedsuren; Breysse, Patrick N

2015-01-01

Background: Coal-fired thermal power plants (TPPs) in Mongolia use various types of asbestos-containing materials (ACMs) in thermal insulation of piping systems, furnaces, and other products. Objective: To investigate the occupational exposure of insulation workers to airborne asbestos in Mongolian power plants. Methods: Forty-seven air samples were collected from four power plants in Mongolia during the progress of insulation work. The samples were analyzed by phase contrast microscopy (PCM) and transmission electron microscopy (TEM). Results: The average phase contrast microscopy equivalent (PCME) asbestos fiber concentration was 0.93 f/cm3. Sixteen of the 41 personal and one of the area samples exceeded the United States Occupational Safety and Health Administration (US OSHA) short-term exposure limit of 1.0 f/cm3. If it is assumed that the short-term samples collected are representative of full-shift exposure, then the exposures are approximately 10 times higher than the US OSHA 8-hour permissible exposure limit of 0.1 f/cm3. Conclusion: Power plant insulation workers are exposed to airborne asbestos at concentrations that exceed the US OSHA Permissible Exposure Limit. Action to mitigate the risks should be taken in Mongolia. PMID:25730489

Exposure to airborne asbestos in thermal power plants in Mongolia.

PubMed

Damiran, Naransukh; Silbergeld, Ellen K; Frank, Arthur L; Lkhasuren, Oyuntogos; Ochir, Chimedsuren; Breysse, Patrick N

2015-01-01

Coal-fired thermal power plants (TPPs) in Mongolia use various types of asbestos-containing materials (ACMs) in thermal insulation of piping systems, furnaces, and other products. To investigate the occupational exposure of insulation workers to airborne asbestos in Mongolian power plants. Forty-seven air samples were collected from four power plants in Mongolia during the progress of insulation work. The samples were analyzed by phase contrast microscopy (PCM) and transmission electron microscopy (TEM). The average phase contrast microscopy equivalent (PCME) asbestos fiber concentration was 0·93 f/cm(3). Sixteen of the 41 personal and one of the area samples exceeded the United States Occupational Safety and Health Administration (US OSHA) short-term exposure limit of 1·0 f/cm(3). If it is assumed that the short-term samples collected are representative of full-shift exposure, then the exposures are approximately 10 times higher than the US OSHA 8-hour permissible exposure limit of 0·1 f/cm(3). Power plant insulation workers are exposed to airborne asbestos at concentrations that exceed the US OSHA Permissible Exposure Limit. Action to mitigate the risks should be taken in Mongolia.

Assessment of airborne asbestos exposure during the servicing and handling of automobile asbestos-containing gaskets.

PubMed

Blake, Charles L; Dotson, G Scott; Harbison, Raymond D

2006-07-01

Five test sessions were conducted to assess asbestos exposure during the removal or installation of asbestos-containing gaskets on vehicles. All testing took place within an operative automotive repair facility involving passenger cars and a pickup truck ranging in vintage from late 1960s through 1970s. A professional mechanic performed all shop work including engine disassembly and reassembly, gasket manipulation and parts cleaning. Bulk sample analysis of removed gaskets through polarized light microscopy (PLM) revealed asbestos fiber concentrations ranging between 0 and 75%. Personal and area air samples were collected and analyzed using National Institute of Occupational Safety Health (NIOSH) methods 7400 [phase contrast microscopy (PCM)] and 7402 [transmission electron microscopy (TEM)]. Among all air samples collected, approximately 21% (n = 11) contained chrysotile fibers. The mean PCM and phase contrast microscopy equivalent (PCME) 8-h time weighted average (TWA) concentrations for these samples were 0.0031 fibers/cubic centimeters (f/cc) and 0.0017 f/cc, respectively. Based on these findings, automobile mechanics who worked with asbestos-containing gaskets may have been exposed to concentrations of airborne asbestos concentrations approximately 100 times lower than the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 f/cc.

Radiation exposure for manned Mars surface missions

NASA Technical Reports Server (NTRS)

Simonsen, Lisa C.; Nealy, John E.; Townsend, Lawrence W.; Wilson, John W.

1990-01-01

The Langley cosmic ray transport code and the Langley nucleon transport code (BRYNTRN) are used to quantify the transport and attenuation of galactic cosmic rays (GCR) and solar proton flares through the Martian atmosphere. Surface doses are estimated using both a low density and a high density carbon dioxide model of the atmosphere which, in the vertical direction, provides a total of 16 g/sq cm and 22 g/sq cm of protection, respectively. At the Mars surface during the solar minimum cycle, a blood-forming organ (BFO) dose equivalent of 10.5 to 12 rem/yr due to galactic cosmic ray transport and attenuation is calculated. Estimates of the BFO dose equivalents which would have been incurred from the three large solar flare events of August 1972, November 1960, and February 1956 are also calculated at the surface. Results indicate surface BFO dose equivalents of approximately 2 to 5, 5 to 7, and 8 to 10 rem per event, respectively. Doses are also estimated at altitudes up to 12 km above the Martian surface where the atmosphere will provide less total protection.

Medical and occupational dose reduction in pediatric barium meal procedures

NASA Astrophysics Data System (ADS)

Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Ledesma, J. A.; Legnani, A.; Bunick, A. P.; Sauzen, J.; Yagui, A.; Vosiak, P.

2017-11-01

Doses received in pediatric Barium Meal procedure can be rather high. It is possible to reduce dose values following the recommendations of the European Communities (EC) and the International Commission on Radiological Protection (ICRP). In the present work, the modifications of radiographic techniques made in a Brazilian hospital according to the EC and the ICRP recommendations and their influence on medical and occupational exposure are reported. The procedures of 49 patients before and 44 after the optimization were studied and air kerma-area product (PK,A) values and the effective doses were evaluated. The occupational equivalent doses were measured next to the eyes, under the thyroid shield and on each hand of both professionals who remained inside the examination room. The implemented modifications reduced by 70% and 60% the PK,A and the patient effective dose, respectively. The obtained dose values are lower than approximately 75% of the results from similar studies. The occupational annual equivalent doses for all studied organs became lower than the limits set by the ICRP. The equivalent doses in one examination were on average below than 75% of similar studies.

Can we use the equivalent sphere model to approximate organ doses in space radiation environments?

NASA Astrophysics Data System (ADS)

Lin, Zi-Wei

For space radiation protection one often calculates the dose or dose equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However, previous studies have concluded that a 5cm sphere gives a very different dose from the exact BFO dose. One study concludes that a 9cm sphere is a reasonable approximation for the BFO dose in solar particle event (SPE) environments. In this study we investigate the reason behind these observations and extend earlier studies by studying whether BFO, eyes or the skin can be approximated by the equivalent sphere model in different space radiation environments such as solar particle events and galactic cosmic ray (GCR) environments. We take the thickness distribution functions of the organs from the CAM (Computerized Anatomical Man) model, then use a deterministic radiation transport to calculate organ doses in different space radiation environments. The organ doses have been evaluated with a water or aluminum shielding from 0 to 20 g/cm2. We then compare these exact doses with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we propose to use a modified equivalent sphere model with two radius parameters to represent the skin or eyes. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for eyes or the skin. For galactic cosmic rays environments, the equivalent sphere model with one organ-specific radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of eyes or the skin, but is unacceptable for the dose of eyes or the skin. The BFO radius parameters are found to be significantly larger than 5 cm in all cases, consistent with the conclusion of an earlier study. The radius parameters for the dose equivalent in GCR environments are approximately between 10 and 11 cm for the BFO, 3.7 to 4.8 cm for eyes, and 3.5 to 5.6 cm for the skin; while the radius parameters are between 10 and 13 cm for the BFO dose. In the proposed modified equivalent sphere model, the range of each of the two radius parameters for the skin (or eyes) is much tighter than that in the equivalent sphere model with one radius parameter. Our results thus show that the equivalent sphere model works better in galactic cosmic rays environments than in solar particle events. The model works well or marginally well for BFO but usually does not work for eyes or the skin. A modified model with two radius parameters works much better in approximating the dose and dose equivalent in eyes or the skin.

Dioxin exposure in breast milk and infant neurodevelopment in Vietnam.

PubMed

Tai, Pham The; Nishijo, Muneko; Anh, Nguyen Thi Nguyet; Maruzeni, Shoko; Nakagawa, Hideaki; Van Luong, Hoang; Anh, Tran Hai; Honda, Ryumon; Kido, Teruhiko; Nishijo, Hisao

2013-09-01

Dioxin levels in the breast milk of mothers residing near hot spots of dioxin contamination areas in South Vietnam remain much higher than in unsprayed areas, suggesting that fetuses and breast-fed infants may be exposed to high levels of dioxins. The present study investigated the association of infant neurodevelopment in early infancy and dioxin exposure during the perinatal period. The study involved 216 mother-infant pairs living near the Da Nang airbase, a dioxin contaminated area in Vietnam. Mothers and infants were followed from birth until infants were 4 months old. Dioxin levels in breast milk were measured to estimate the perinatal dioxin exposure, including the infant daily dioxin intake (DDI) via breastfeeding. Infant neurodevelopmental parameters, including cognitive, language and motor domains were assessed at approximately 4 months using the Bayley Scales of Infant and Toddler Development, third edition (Bayley-III). The level of 2,3,7,8-tetrachlorodibenzo-p-dioxin and polychlorinated dibenzo-p-dioxins/furans-toxic equivalents in breast milk and the infant DDI showed significant inverse correlations with neurodevelopmental scores. When the subjects were divided into four groups according to dioxin levels in breast milk, the moderate and high DDI groups had significantly lower cognitive, composite motor and fine motor scores, and the high polychlorinated dibenzo-p-dioxins/furans-toxic equivalents group had significantly lower fine motor score than the low exposure group. For all domains, neurodevelopmental scores were decreased with increase in the level of 2,3,7,8-tetrachlorodibenzo-p-dioxin. The present study demonstrates a considerable impact of perinatal dioxin exposure on neurodevelopment in 4-month-old infants living in contaminated areas in Vietnam.

Two-photon equivalent weighting of spatial excimer laser beam profiles

NASA Astrophysics Data System (ADS)

Eva, Eric; Bauer, Harry H.; Metzger, K.; Pfeiffer, A.

2001-04-01

Damage in optical materials for semiconductor lithography applications caused by exposure to 248 or 193 nm light is usually two-photon driven, hence it is a nonlinear function of incident intensity. Materials should be tested with flat- topped temporal and spatial laser beam profiles to facilitate interpretation of data, but in reality this is hard to achieve. Sandstrom provided a formula that approximates any given temporal pulse shape with a two- photon equivalent rectangular pulse (Second Symposium on 193 nm Lithography, Colorado Springs 1997). Known as the integral-square pulse duration, this definition has been embraced as an industry standard. Originally faced with the problem of comparing results obtained with pseudo-Gaussian spatial profiles to literature data, we found that a general solution for arbitrarily inhomogeneous spatial beam profiles exists which results in a definition much similar to Sandstrom's. In addition, we proved the validity of our approach in experiments with intentionally altered beam profiles.

Biodosimetry Based on γ-H2AX Quantification and Cytogenetics after Partial- and Total-Body Irradiation during Fractionated Radiotherapy.

PubMed

Zahnreich, Sebastian; Ebersberger, Anne; Kaina, Bernd; Schmidberger, Heinz

2015-04-01

The aim of this current study was to quantitatively describe radiation-induced DNA damage and its distribution in leukocytes of cancer patients after fractionated partial- or total-body radiotherapy. Specifically, the impact of exposed anatomic region and administered dose was investigated in breast and prostate cancer patients receiving partial-body radiotherapy. DNA double-strand breaks (DSBs) were quantified by γ-H2AX immunostaining. The frequency of unstable chromosomal aberrations in stimulated lymphocytes was also determined and compared with the frequency of DNA DSBs in the same samples. The frequency of radiation-induced DNA damage was converted into dose, using ex vivo generated calibration curves, and was then compared with the administered physical dose. This study showed that 0.5 h after partial-body radiotherapy the quantity of radiation-induced γ-H2AX foci increased linearly with the administered equivalent whole-body dose for both tumor entities. Foci frequencies dropped 1 day thereafter but proportionality to the equivalent whole-body dose was maintained. Conversely, the frequency of radiation-induced cytogenetic damage increased from 0.5 h to 1 day after the first partial-body exposure with a linear dependence on the administered equivalent whole-body dose, for prostate cancer patients only. Only γ-H2AX foci assessment immediately after partial-body radiotherapy was a reliable measure of the expected equivalent whole-body dose. Local tumor doses could be approximated with both assays after one day. After total-body radiotherapy satisfactory dose estimates were achieved with both assays up to 8 h after exposure. In conclusion, the quantification of radiation-induced γ-H2AX foci, but not cytogenetic damage in peripheral leukocytes was a sensitive and rapid biodosimeter after acute heterogeneous irradiation of partial body volumes that was able to primarily assess the absorbed equivalent whole-body dose.

FDA-sunlamp recommended Maximum Timer Interval And Exposure Schedule: consensus ISO/CIE dose equivalence.

PubMed

Dowdy, John C; Czako, Eugene A; Stepp, Michael E; Schlitt, Steven C; Bender, Gregory R; Khan, Lateef U; Shinneman, Kenneth D; Karos, Manuel G; Shepherd, James G; Sayre, Robert M

2011-09-01

The authors compared calculations of sunlamp maximum exposure times following current USFDA Guidance Policy on the Maximum Timer Interval and Exposure Schedule, with USFDA/CDRH proposals revising these to equivalent erythemal exposures of ISO/CIE Standard Erythema Dose (SED). In 2003, [USFDA/CDRH proposed replacing their unique CDRH/Lytle] erythema action spectrum with the ISO/CIE erythema action spectrum and revising the sunlamp maximum exposure timer to 600 J m(-2) ISO/CIE effective dose, presented as being biologically equivalent. Preliminary analysis failed to confirm said equivalence, indicating instead ∼38% increased exposure when applying these proposed revisions. To confirm and refine this finding, a collaboration of tanning bed and UV lamp manufacturers compiled 89 UV spectra representing a broad sampling of U.S. indoor tanning equipment. USFDA maximum recommended exposure time (Te) per current sunlamp guidance and CIE erythemal effectiveness per ISO/CIE standard were calculated. The CIE effective dose delivered per Te averaged 456 J(CIE) m(-2) (SD = 0.17) or ∼4.5 SED. The authors found that CDRH's proposed 600 J(CIE) m(-2) recommended maximum sunlamp exposure exceeds current Te erythemal dose by ∼33%. The current USFDA 0.75 MED initial exposure was ∼0.9 SED, consistent with 1.0 SED initial dose in existing international sunlamp standards. As no sunlamps analyzed exceeded 5 SED, a revised maximum exposure of 500 J(CIE) m(-2) (∼80% of CDRH's proposal) should be compatible with existing tanning equipment. A tanning acclimatization schedule is proposed beginning at 1 SED thrice-weekly, increasing uniformly stepwise over 4 wk to a 5 SED maximum exposure in conjunction with a tan maintenance schedule of twice-weekly 5 SED sessions, as biologically equivalent to current USFDA sunlamp policy.

Testing of the European Union exposure-response relationships and annoyance equivalents model for annoyance due to transportation noises: The need of revised exposure-response relationships and annoyance equivalents model.

PubMed

Gille, Laure-Anne; Marquis-Favre, Catherine; Morel, Julien

2016-09-01

An in situ survey was performed in 8 French cities in 2012 to study the annoyance due to combined transportation noises. As the European Commission recommends to use the exposure-response relationships suggested by Miedema and Oudshoorn [Environmental Health Perspective, 2001] to predict annoyance due to single transportation noise, these exposure-response relationships were tested using the annoyance due to each transportation noise measured during the French survey. These relationships only enabled a good prediction in terms of the percentages of people highly annoyed by road traffic noise. For the percentages of people annoyed and a little annoyed by road traffic noise, the quality of prediction is weak. For aircraft and railway noises, prediction of annoyance is not satisfactory either. As a consequence, the annoyance equivalents model of Miedema [The Journal of the Acoustical Society of America, 2004], based on these exposure-response relationships did not enable a good prediction of annoyance due to combined transportation noises. Local exposure-response relationships were derived, following the whole computation suggested by Miedema and Oudshoorn [Environmental Health Perspective, 2001]. They led to a better calculation of annoyance due to each transportation noise in the French cities. A new version of the annoyance equivalents model was proposed using these new exposure-response relationships. This model enabled a better prediction of the total annoyance due to the combined transportation noises. These results encourage therefore to improve the annoyance prediction for noise in isolation with local or revised exposure-response relationships, which will also contribute to improve annoyance modeling for combined noises. With this aim in mind, a methodology is proposed to consider noise sensitivity in exposure-response relationships and in the annoyance equivalents model. The results showed that taking into account such variable did not enable to enhance both exposure-response relationships and the annoyance equivalents model. Copyright © 2016 Elsevier Ltd. All rights reserved.

On the Formation and Seasonal Properties of Topical Cirrus Clouds over Amazon Basin (2.89ºS, 59.97ºW): Observations from Lidar, Radiosonde and Satellite instruments.

NASA Astrophysics Data System (ADS)

Blagev, D. P.; Mendoza, D. L.; Rea, S.; Sorensen, J.

2014-12-01

Adverse health effects have been associated with urban pollutant exposure arising from close proximity to highly-emitting sources and atmospheric mixing. The relative air pollution exposure dose and time effects on various diseases remains unknown. This study compares the increased risk of health complications when patients are exposed to short term high-levels of air pollution vs. longer term exposure to lower levels of air pollution. We used the electronic medical record of an integrated hospital system based in Utah, Intermountain Healthcare, to identify a cohort of patients with Chronic Obstructive Pulmonary Disease (COPD) who were seen between 2009-2014. We determined patient demographics as well as comorbidity data and healthcare utilization. To determine the approximate air pollution dose and time exposure, we used the Hestia highly-resolved emissions inventory for Salt Lake County, Utah in conjunction with emissions based on the National Emissions Inventory (NEI). Hourly emissions of CO2 and criteria air pollutants were gridded at a 0.002o x 0.002o resolution for the study years. The resulting emissions were transported using the CALPUFF and AERMOD dispersion models to estimate air pollutant concentrations at an hourly 0.002o x 0.002oresolution. Additionally, pollutant concentrations were estimated at each patient's home and work address to estimate exposure. Multivariate analysis adjusting for patient demographics, comorbidities and severity of COPD was performed to determine association between air pollution exposure and the risk of hospitalization or emergency department (ED) visit for COPD exacerbation and an equivalency estimate for air pollution exposure was developed. We noted associations with air pollution levels for each pollutant and hospitalizations and ED visits for COPD and other patient comorbidities. We also present an equivalency estimate for dose of air pollution exposure and health outcomes. This analysis compares the increased risk of health complications when patients are exposed to short term high-levels of air pollution vs. longer term exposure to lower levels of air pollution. These findings highlight pollutant emissions and exposures spatial and temporal heterogeneity and associated health effects.

Interaction between Chronic Obstructive Pulmonary Disease (COPD) and other important health conditions and measurable air pollution

NASA Astrophysics Data System (ADS)

Blagev, D. P.; Mendoza, D. L.; Rea, S.; Sorensen, J.

2015-12-01

Adverse health effects have been associated with urban pollutant exposure arising from close proximity to highly-emitting sources and atmospheric mixing. The relative air pollution exposure dose and time effects on various diseases remains unknown. This study compares the increased risk of health complications when patients are exposed to short term high-levels of air pollution vs. longer term exposure to lower levels of air pollution. We used the electronic medical record of an integrated hospital system based in Utah, Intermountain Healthcare, to identify a cohort of patients with Chronic Obstructive Pulmonary Disease (COPD) who were seen between 2009-2014. We determined patient demographics as well as comorbidity data and healthcare utilization. To determine the approximate air pollution dose and time exposure, we used the Hestia highly-resolved emissions inventory for Salt Lake County, Utah in conjunction with emissions based on the National Emissions Inventory (NEI). Hourly emissions of CO2 and criteria air pollutants were gridded at a 0.002o x 0.002o resolution for the study years. The resulting emissions were transported using the CALPUFF and AERMOD dispersion models to estimate air pollutant concentrations at an hourly 0.002o x 0.002oresolution. Additionally, pollutant concentrations were estimated at each patient's home and work address to estimate exposure. Multivariate analysis adjusting for patient demographics, comorbidities and severity of COPD was performed to determine association between air pollution exposure and the risk of hospitalization or emergency department (ED) visit for COPD exacerbation and an equivalency estimate for air pollution exposure was developed. We noted associations with air pollution levels for each pollutant and hospitalizations and ED visits for COPD and other patient comorbidities. We also present an equivalency estimate for dose of air pollution exposure and health outcomes. This analysis compares the increased risk of health complications when patients are exposed to short term high-levels of air pollution vs. longer term exposure to lower levels of air pollution. These findings highlight pollutant emissions and exposures spatial and temporal heterogeneity and associated health effects.

Comparison of Annoyance from Railway Noise and Railway Vibration

PubMed Central

Gidlöf-Gunnarsson, Anita; Gustavsson, Sara

2017-01-01

The aim of this study is to compare vibration exposure to noise exposure from railway traffic in terms of equal annoyance, i.e., to determine when a certain noise level is equally annoying as a corresponding vibration velocity. Based on questionnaire data from the Train Vibration and Noise Effects (TVANE) research project from residential areas exposed to railway noise and vibration, the dose response relationship for annoyance was estimated. By comparing the relationships between exposure and annoyance for areas both with and without significant vibration exposure, the noise levels and vibration velocities that had an equal probability of causing annoyance was determined using logistic regression. The comparison gives a continuous mapping between vibration velocity in the ground and a corresponding noise level at the facade that are equally annoying. For equivalent noise level at the facade compared to maximum weighted vibration velocity in the ground the probability of annoyance is approximately 20% for 59 dB or 0.48 mm/s, and about 40% for 63 dB or 0.98 mm/s. PMID:28753921

Fire test methodology for aerospace materials. 1: Thermal and smoke toxicological assessments of graphite/bismaleimide and graphite/epoxy systems

NASA Technical Reports Server (NTRS)

Kanakia, M. D.; Switzer, W. G.; Hartzell, G. E.; Kaplan, H. L.

1980-01-01

Both materials possess a high degree of thermal stability, with total heat release values being essentially identical under piloted ignition conditions over a range of 5 to 10 W/sq cm incident heat flux. The graphite/epoxy material had a tendency to auto-ignite at a lower heat flux (about 7 W/sq cm) and produced about 23 percent higher peak heat release rates, approximately 42 percent more carbon monoxide and considerably more smoke than the graphite/bismaleimide under conditions of piloted ignition. Toxicological potencies of smoke produced from the two composites were equivalent for 30 minute exposures. Potencies were also comparable to many common materials, such as wood. There was no evidence for the formation of an "unusual toxicant" nor for any short term post-exposure toxicological effects.

Carboxyhemoglobin: a primer for clinicians.

PubMed

Hampson, Neil B

2018-01-01

One of carbon monoxide's several mechanisms of toxicity is binding with circulating hemoglobin to form carboxyhemoglobin, resulting in a functional anemia. While patients with carbon monoxide poisoning are often said to be "cherry-red," such discoloration is rarely seen. Carboxyhemoglobin levels cannot be measured with conventional pulse oximetry, can be approximated with pulse CO-oximetry, and are most accurately measured with a laboratory CO-oximeter. Carboxyhemoglobin levels are quite stable and can be accurately measured on a transported blood sample. For clinical purposes, arterial and venous carboxyhemoglobin levels can be considered to be equivalent. Carboxyhemoglobin levels are typically lower than 2% in non-smokers and lower than 5% in smokers. A level over 9% is almost always due to exogenous carbon monoxide exposure, even among smokers. Conversely, a low level does not exclude significant exposure under certain circumstances. As carboxyhemoglobin levels of poisoned patients do not correlate with symptoms or outcome, their greatest utility is a marker of exposure. Copyright© Undersea and Hyperbaric Medical Society.

Can the Equivalent Sphere Model Approximate Organ Doses in Space Radiation Environments?

NASA Technical Reports Server (NTRS)

Zi-Wei, Lin

2007-01-01

In space radiation calculations it is often useful to calculate the dose or dose equivalent in blood-forming organs (BFO). the skin or the eye. It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However previous studies have shown that a 5cm sphere gives conservative dose values for BFO. In this study we use a deterministic radiation transport with the Computerized Anatomical Man model to investigate whether the equivalent sphere model can approximate organ doses in space radiation environments. We find that for galactic cosmic rays environments the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent and marginally well for the BFO dose and the dose equivalent of the eye or the skin. For solar particle events the radius parameters for the organ dose equivalent increase with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin The ranges of the radius parameters are also shown and the BFO radius parameters are found to be significantly larger than 5 cm in all eases.

Oxygenation state and twilight vision at 2438 m.

PubMed

Connolly, Desmond M

2011-01-01

Under twilight viewing conditions, hypoxia, equivalent to breathing air at 3048 m (10,000 ft), compromises low contrast acuity, dynamic contrast sensitivity, and chromatic sensitivity. Selected past experiments have been repeated under milder hypoxia, equivalent to altitude exposure below 2438 m (8000 ft), to further define the influence of oxygenation state on mesopic vision. To assess photopic and mesopic visual function, 12 subjects each undertook three experiments using the Contrast Acuity Assessment test, the Frequency Doubling Perimeter, and the Color Assessment and Diagnosis (CAD) test. Experiments were conducted near sea level breathing 15.2% oxygen (balance nitrogen) and 100% oxygen, representing mild hypobaric hypoxia at 2438 m (8000 ft) and the benefit of supplementary oxygen, respectively. Oxygenation state was a statistically significant determinant of visual performance on all three visual parameters at mesopic, but not photopic, luminance. Mesopic sensitivity was greater with supplementary oxygen, but the magnitude of each hypoxic decrement was slight. Hypoxia elevated mesopic contrast acuity thresholds by approximately 4%; decreased mesopic dynamic contrast sensitivity by approximately 2 dB; and extended mean color ellipse axis length by approximately one CAD unit at mesopic luminance (that is, hypoxia decreased chromatic sensitivity). The results indicate that twilight vision may be susceptible to conditions of altered oxygenation at upper-to-mid mesopic luminance with relevance to contemporary night flying, including using night vision devices. Supplementary oxygen should be considered when optimal visual performance is mission-critical during flight above 2438 m (8000 ft) in dim light.

Usage of personal music players in adolescents and its association with noise-induced hearing loss: A cross-sectional analysis of Ohrkan cohort study data.

PubMed

Twardella, Dorothee; Raab, Ulla; Perez-Alvarez, Carmelo; Steffens, Thomas; Bolte, Gabriele; Fromme, Hermann

2017-01-01

To describe personal music player (PMP) usage among adolescents, sociodemographic determinants and association with audiometric notches. Audiometric evaluation to assess hearing status, and standardized questionnaires to evaluate PMP listening behaviors, leisure noise exposures and self-reported hearing loss symptoms. Sociodemographic information was collected using a parent questionnaire. Noise exposure by PMP usage equivalent for a 40 h week was estimated based on self-reported volume and duration of use. A total of 2143 students (54% females) attending 9th grade in Regensburg, Germany, during 2009 to 2011. Overall, 85% of the students reported using PMPs. Exposure level exceeded 80 dB(A) in approximately one third, and 85 dB(A) in one quarter, of those who used PMP. An audiometric notch was found in 2.3% of participants, but was not significantly associated with higher PMP exposure. PMP exposure above the occupational limits of 80 and 85 dB(A) set by the Directive 2003/10/EC may be a risk factor for developing noise-induced hearing loss. Educational measures to ameliorate high risk behaviors in PMP usage are needed, particularly for socially disadvantaged groups.

Uptake, tissue distribution, and metabolism of malachite green in the channel catfish (Ictalurus punctatus)

USGS Publications Warehouse

Plakas, S.M.; El Said, K. R.; Stehly, G.R.; Gingerich, W.H.; Allen, J.L.

1996-01-01

The disposition of malachite green was determined in channel catfish (Ictalurus punctatus) after intravascular dosing (0.8 mg . Kg-1) or waterborne exposure (0.8 mg . L-1 for 1 h). After intravascular dosing, mean plasma concentrations of the parent compound exhibited a triphasic decline with a terminal elimination half-life of 6.2 h. Malachite green was rapidly absorbed and concentrated in the tissues during waterborne exposure. The rate of accumulation was directly related to pH of the exposure water. After waterborne exposure, elimination of the parent compound from plasma also was triphasic with a terminal half-life of 4.7 h. In muscle, the half-life of the parent compound was approximately 67 h. Malachite green and its metabolites were widely distributed in all tissues. In fish exposed to C-14-labeled malachite green, total drug equivalent concentrations were highest in abdominal fat and lowest in plasma. Malachite green was rapidly and extensively metabolized to its reduced form, leucomalachite green, which was slowly eliminated from the tissues. Leucomalachite green is an appropriate target analyte for monitoring exposure of channel catfish to this drug.

The variability of atmospheric equivalent temperature for radar altimeter range correction

NASA Technical Reports Server (NTRS)

Liu, W. Timothy; Mock, Donald

1990-01-01

Two sets of data were used to test the validity of the presently used approximation for radar altimeter range correction due to atmospheric water vapor. The approximation includes an assumption of constant atmospheric equivalent temperature. The first data set includes monthly, three-dimensional, gridded temperature and humidity fields over global oceans for a 10-year period, and the second is comprised of daily or semidaily rawinsonde data at 17 island stations for a 7-year period. It is found that the standard method underestimates the variability of the equivalent temperature, and the approximation could introduce errors of 2 cm for monthly means. The equivalent temperature is found to have a strong meridional gradient, and the highest temporal variabilities are found over western boundary currents. The study affirms that the atmospheric water vapor is a good predictor for both the equivalent temperature and the range correction. A relation is proposed to reduce the error.

Effects of hyperbaric exposure on eyes with intraocular gas bubbles.

PubMed

Jackman, S V; Thompson, J T

1995-01-01

Air travel is known to be potentially hazardous for patients with intraocular gas bubbles, and the external pressure changes associated with hyperbaric oxygen therapy and scuba diving could be similarly dangerous. Rabbits with a perfluoropropane/air gas mixture filling approximately 60% of the vitreous cavity of the right eye were exposed to 3 different hyperbaric pressure profiles to an equivalent depth of 33 feet. The first group were a control group and were not exposed to hyperbaric pressures. The second group remained at an equivalent depth of 33 feet for 30 minutes, and the third group remained at 33 feet for 1 minute. Both groups ascended to normal atmospheric pressure at a rate of 1 foot per minute. The fourth group remained at 33 feet for 1 minute and then ascended at a rate of 0.2 feet per minute. In all eyes with an intraocular gas bubble, intraocular pressure dropped to zero when the atmospheric pressure was increased, and rose to more than 50 mmHg when the atmospheric pressure was returned to normal. Pressures in excess of 50 mmHg were sustained for 10 minutes or longer in each rabbit exposed to one of the hyperbaric profiles. No significant intraocular pressure changes were observed in eyes without an intraocular gas bubble or eyes not exposed to hyperbaric pressure. Marked elevation in intraocular pressure occurs as a result of hyperbaric exposure in eyes with an intraocular gas bubble. Hyperbaric exposure is therefore not advisable for patients with intraocular gas bubbles.

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.

Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

NASA Astrophysics Data System (ADS)

Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.; Brune, W. H.; Hunter, J. F.; Kroll, J. H.; Cummings, M. J.; Brogan, J. F.; Parmar, Y.; Worsnop, D. R.; Kolb, C. E.; Davidovits, P.

2015-03-01

We performed a systematic intercomparison study of the chemistry and yields of secondary organic aerosol (SOA) generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0 × 108 to 2.2 × 1010 molec cm-3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 106 to 2 × 107 molec cm-3 over exposure times of several hours. The OH concentration in the chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. In most cases, for a specific SOA type the most-oxidized chamber SOA and the least-oxidized flow reactor SOA have similar mass spectra, oxygen-to-carbon and hydrogen-to-carbon ratios, and carbon oxidation states at integrated OH exposures between approximately 1 × 1011 and 2 × 1011 molec cm-3 s, or about 1-2 days of equivalent atmospheric oxidation. This observation suggests that in the range of available OH exposure overlap for the flow reactor and chambers, SOA elemental composition as measured by an aerosol mass spectrometer is similar whether the precursor is exposed to low OH concentrations over long exposure times or high OH concentrations over short exposure times. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed particles are routinely used.

Dose conversion coefficients for photon exposure of the human eye lens.

PubMed

Behrens, R; Dietze, G

2011-01-21

In recent years, several papers dealing with the eye lens dose have been published, because epidemiological studies implied that the induction of cataracts occurs even at eye lens doses of less than 500 mGy. Different questions were addressed: Which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens? Is a new definition of the dose quantity H(p)(3) based on a cylinder phantom to represent the human head necessary? Are current conversion coefficients from fluence to equivalent dose to the lens sufficiently accurate? To investigate the latter question, a realistic model of the eye including the inner structure of the lens was developed. Using this eye model, conversion coefficients for electrons have already been presented. In this paper, the same eye model-with the addition of the whole body-was used to calculate conversion coefficients from fluence (and air kerma) to equivalent dose to the lens for photon radiation from 5 keV to 10 MeV. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are similar between 40 keV and 1 MeV and lower by up to a factor of 5 and 7 for photon energies at about 10 keV and 10 MeV, respectively. Above 1 MeV, the new values (calculated without kerma approximation) should be applied in pure photon radiation fields, while the values adopted by the ICRP in 1996 (calculated with kerma approximation) should be applied in case a significant contribution from secondary electrons originating outside the body is present.

Dose conversion coefficients for photon exposure of the human eye lens

NASA Astrophysics Data System (ADS)

Behrens, R.; Dietze, G.

2011-01-01

In recent years, several papers dealing with the eye lens dose have been published, because epidemiological studies implied that the induction of cataracts occurs even at eye lens doses of less than 500 mGy. Different questions were addressed: Which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens? Is a new definition of the dose quantity Hp(3) based on a cylinder phantom to represent the human head necessary? Are current conversion coefficients from fluence to equivalent dose to the lens sufficiently accurate? To investigate the latter question, a realistic model of the eye including the inner structure of the lens was developed. Using this eye model, conversion coefficients for electrons have already been presented. In this paper, the same eye model—with the addition of the whole body—was used to calculate conversion coefficients from fluence (and air kerma) to equivalent dose to the lens for photon radiation from 5 keV to 10 MeV. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are similar between 40 keV and 1 MeV and lower by up to a factor of 5 and 7 for photon energies at about 10 keV and 10 MeV, respectively. Above 1 MeV, the new values (calculated without kerma approximation) should be applied in pure photon radiation fields, while the values adopted by the ICRP in 1996 (calculated with kerma approximation) should be applied in case a significant contribution from secondary electrons originating outside the body is present.

Accumulation of stimulants of Toll-like receptor (TLR)-2 and TLR4 in meat products stored at 5 °C.

PubMed

Erridge, Clett

2011-03-01

Recent evidence suggests that exposure to stimulants of the innate immune receptors Toll-like receptor (TLR)-2 and TLR4 may contribute to the development of atherosclerosis and insulin resistance. We showed recently that common foodsuffs can contain TLR-stimulants, and that the greatest concentrations were present in meat-based products. Using a recently developed quantitative bioassay, we here examined the kinetics of accumulation of TLR2- and TLR4-stimulants in a variety of meat products held at 5 °C in air or under a modified atmosphere for up to 8 d. Meat content of TLR-stimulants increased with time in each meat examined and was paralleled by growth of pseudomonads and Enterobacteriaceae, suggesting that bacterial lipopeptides and lipopolysaccharides are the likely sources of TLR2- and TLR4-stimulants, respectively. TLR-stimulants reached the highest levels (approximately 80 μg lipopeptide-equivalents per gramme and approximately 7 μg lipopolysaccharide-equivalents per gram) in meat that was minced rather than intact, and when stored in air rather than under a modified atmosphere. TLR2- and TLR4-stimulants in meat products cooked for 1 h retained approximately 20% and approximately 40% of their bioactivity, respectively. In summary, storage conditions and microbial flora critically regulate the kinetics of TLR2- and TLR4-stimulant accumulation in meat products and these may retain biological activity after cooking. The novel assays presented in this work could be used to predict the potential of foodstuffs to promote inflammatory signaling in human subjects, which may be deleterious to health. These assays may also be used to monitor the historical microbial flora in food products after cooking or other forms of food processing may have rendered the original microflora nonviable.

Can the Equivalent Sphere Model Approximate Organ Doses in Space?

NASA Technical Reports Server (NTRS)

Lin, Zi-Wei

2007-01-01

For space radiation protection it is often useful to calculate dose or dose,equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to. simulate the BFO dose. However, many previous studies have concluded that a 5cm sphere gives very different dose values from the exact BFO values. One study [1] . concludes that a 9 cm sphere is a reasonable approximation for BFO'doses in solar particle event environments. In this study we use a deterministic radiation transport [2] to investigate the reason behind these observations and to extend earlier studies. We take different space radiation environments, including seven galactic cosmic ray environments and six large solar particle events, and calculate the dose and dose equivalent in the skin, eyes and BFO using their thickness distribution functions from the CAM (Computerized Anatomical Man) model [3] The organ doses have been evaluated with a water or aluminum shielding of an areal density from 0 to 20 g/sq cm. We then compare with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we address why the equivalent sphere model is not a good approximation in some cases. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin. For galactic cosmic rays environments, the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of the eye or the skin, but is unacceptable for the dose of the eye or the skin. The ranges of the radius parameters are also being investigated, and the BFO radius parameters are found to be significantly, larger than 5 cm in all cases, consistent with the conclusion of an earlier study [I]. The radius parameters for the dose equivalent in GCR environments are approximately between 10 and I I cm for the BFO, 3.7 to 4.8 cm for the eye, and 3.5 to 5.6 cm for the skin; while the radius parameters are between 10 and 13 cm for the BFO dose.

Measured and Calculated Neutron Spectra and Dose Equivalent Rates at High Altitudes; Relevance to SST Operations and Space Research

NASA Technical Reports Server (NTRS)

Foelsche, T.; Mendell, R. B.; Wilson, J. W.; Adams, R. R.

1974-01-01

Results of the NASA Langley-New York University high-altitude radiation study are presented. Measurements of the absorbed dose rate and of secondary fast neutrons (1 to 10 MeV energy) during the years 1965 to 1971 are used to determine the maximum radiation exposure from galactic and solar cosmic rays of supersonic transport (SST) and subsonic jet occupants. The maximum dose equivalent rates that the SST crews might receive turn out to be 13 to 20 percent of the maximum permissible dose rate (MPD) for radiation workers (5 rem/yr). The exposure of passengers encountering an intense giant-energy solar particle event could exceed the MPD for the general population (0.5 rem/yr), but would be within these permissible limits if in such rare cases the transport descends to subsonic altitude; it is in general less than 12 percent of the MPD. By Monte Carlo calculations of the transport and buildup of nucleons in air for incident proton energies E of 0.02 to 10 GeV, the measured neutron spectra were extrapolated to lower and higher energies and for galactic cosmic rays were found to continue with a relatively high intensity to energies greater than 400 MeV, in a wide altitude range. This condition, together with the measured intensity profiles of fast neutrons, revealed that the biologically important fast and energetic neutrons penetrate deep into the atmosphere and contribute approximately 50 percent of the dose equivalant rates at SST and present subsonic jet altitudes.

Influence of ice and snow covers on the UV exposure of terrestrial microbial communities: dosimetric studies.

PubMed

Cockell, Charles S; Rettberg, Petra; Horneck, Gerda; Wynn-Williams, David D; Scherer, Kerstin; Gugg-Helminger, Anton

2002-08-01

Bacillus subtilis spore biological dosimeters and electronic dosimeters were used to investigate the exposure of terrestrial microbial communities in micro-habitats covered by snow and ice in Antarctica. The melting of snow covers of between 5- and 15-cm thickness, depending on age and heterogeneity, could increase B. subtilis spore inactivation by up to an order of magnitude, a relative increase twice that caused by a 50% ozone depletion. Within the snow-pack at depths of less than approximately 3 cm snow algae could receive two to three times the DNA-weighted irradiance they would receive on bare ground. At the edge of the snow-pack, warming of low albedo soils resulted in the formation of overhangs that provided transient UV protection to thawed and growing microbial communities on the soils underneath. In shallow aquatic habitats, thin layers of heterogeneous ice of a few millimetres thickness were found to reduce DNA-weighted irradiances by up to 55% compared to full-sky values with equivalent DNA-weighted diffuse attenuation coefficients (K(DNA)) of >200 m(-1). A 2-mm snow-encrusted ice cover on a pond was equivalent to 10 cm of ice on a perennially ice covered lake. Ice covers also had the effect of stabilizing the UV exposure, which was often subject to rapid variations of up to 33% of the mean value caused by wind-rippling of the water surface. These data show that changing ice and snow covers cause relative changes in microbial UV exposure at least as great as those caused by changing ozone column abundance. Copyright 2002 Elsevier Science B.V.

Low-energy electron effects on tensile modulus and infrared transmission properties of a polypyromellitimide film

NASA Technical Reports Server (NTRS)

Ferl, J. E.; Long, E. R., Jr.

1981-01-01

Infrared (IR) spectroscopy and tensile modulus testing were used to evaluate the importance of experimental procedure on changes in properties of pyromellitic dianhydride-p,p prime-oxydianiline film exposed to electron radiation. The radiation exposures were accelerated, approximate equivalents to the total dose expected for a 30 year mission in geosynchronous Earth orbit. The change in the tensile modulus depends more on the dose rate and the time interval between exposure and testing than on total dose. The IR data vary with both total dose and dose rate. A threshold dose rate exists below which reversible radiation effects on the IR spectra occur. Above the threshold dose rate, irreversible effects occur with the appearance of a new band. Post-irradiation and in situ IR absorption bands are significantly different. It is suggested that the electron radiation induced metastable, excites molecular states.

VizieR Online Data Catalog: Spectral atlas of HD 50138 (Borges Fernandes+, 2009)

NASA Astrophysics Data System (ADS)

Borges Fernandes, M.; Kraus, M.; Chesneau, O.; Domiciano de Souza, A.; de Araujo, F. X.; Stee, P.; Meilland, A.

2009-09-01

In this table, it is described the lines identified, with their radial velocities and equivalent widths in the high-resolution FEROS spectra obtained in 1999 and 2007. FEROS is a bench-mounted Echelle spectrograph with fibers, which covers a sky area of 2" of diameter, with a wavelength coverage from 360nm to 920nm and a spectral resolution of R=55000 (in the region around 600nm). The spectrum of 1999 was obtained with an exposure time of 180 seconds and has a S/N ratio of approximately 80 in the 550nm region. In 2007, we were able to take two consecutive spectra of the star, both with 180 seconds of exposure time. Since these spectra do not show significant differences, we added them up for a better S/N ratio, which is around 250. (1 data file).

Exposure of the surgeon's hands to radiation during hand surgery procedures.

PubMed

Żyluk, Andrzej; Puchalski, Piotr; Szlosser, Zbigniew; Dec, Paweł; Chrąchol, Joanna

2014-01-01

The objective of the study was to assess the time of exposure of the surgeon's hands to radiation and calculate of the equivalent dose absorbed during surgery of hand and wrist fractures with C-arm fluoroscope guidance. The necessary data specified by the objective of the study were acquired from operations of 287 patients with fractures of fingers, metacarpals, wrist bones and distal radius. 218 operations (78%) were percutaneous procedures and 60 (22%) were performed by open method. Data on the time of exposure and dose of radiation were acquired from the display of the fluoroscope, where they were automatically generated. These data were assigned to the individual patient, type of fracture, method of surgery and the operating surgeon. Fixations of distal radial fractures required longer times of radiation exposure (mean 61 sec.) than fractures of the wrist/metacarpals and fingers (38 and 32 sec., respectively), which was associated with absorption of significantly higher equivalent doses. Fixations of distal radial fractures by open method were associated with statistically significantly higher equivalent doses (0.41 mSv) than percutaneous procedures (0.3 mSv). Fixations of wrist and metacarpal bone fractures by open method were associated with lower equivalent doses (0.34 mSv) than percutaneous procedures (0.37 mSv),but the difference was not significant. Fixations of finger fractures by open method were associated with lower equivalent doses (0.13 mSv) than percutaneous procedures (0.24 mSv), the difference being statistically non-significant. Statistically significant differences in exposure time and equivalent doses were noted between 4 surgeons participating in the study, but no definitive relationship was found between these parameters and surgeons' employment time. 1. Hand surgery procedures under fluoroscopic guidance are associated with mild exposure of the surgeons' hands to radiation. 2. The equivalent dose was related to the type of fracture, operative technique and - to some degree - to the time of employment of the surgeon.

Effects of a simulated martian UV flux on the cyanobacterium, Chroococcidiopsis sp. 029.

PubMed

Cockell, Charles S; Schuerger, Andrew C; Billi, Daniela; Friedmann, E Imre; Panitz, Corinna

2005-04-01

Dried monolayers of Chroococcidiopsis sp. 029, a desiccation-tolerant, endolithic cyanobacterium, were exposed to a simulated martian-surface UV and visible light flux, which may also approximate to the worst-case scenario for the Archean Earth. After 5 min, there was a 99% loss of cell viability, and there were no survivors after 30 min. However, this survival was approximately 10 times higher than that previously reported for Bacillus subtilis. We show that under 1 mm of rock, Chroococcidiopsis sp. could survive (and potentially grow) under the high martian UV flux if water and nutrient requirements for growth were met. In isolated cells, phycobilisomes and esterases remained intact hours after viability was lost. Esterase activity was reduced by 99% after a 1-h exposure, while 99% loss of autofluorescence required a 4-h exposure. However, cell morphology was not changed, and DNA was still detectable by 4',6-diamidino-2-phenylindole staining after an 8-h exposure (equivalent to approximately 1 day on Mars at the equator). Under 1 mm of simulant martian soil or gneiss, the effect of UV radiation could not be detected on esterase activity or autofluorescence after 4 h. These results show that under the intense martian UV flux the morphological signatures of life can persist even after viability, enzymatic activity, and pigmentation have been destroyed. Finally, the global dispersal of viable, isolated cells of even this desiccation-tolerant, ionizing-radiation-resistant microorganism on Mars is unlikely as they are killed quickly by unattenuated UV radiation when in a desiccated state. These findings have implications for the survival of diverse microbial contaminants dispersed during the course of human exploratory class missions on the surface of Mars.

Radiation exposure from consumer products and miscellaneous sources

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

Not Available

1977-01-01

This review of the literature indicates that there is a variety of consumer products and miscellaneous sources of radiation that result in exposure to the U.S. population. A summary of the number of people exposed to each such source, an estimate of the resulting dose equivalents to the exposed population, and an estimate of the average annual population dose equivalent are tabulated. A review of the data in this table shows that the total average annual contribution to the whole-body dose equivalent of the U.S. population from consumer products is less than 5 mrem; about 70 percent of this arisesmore » from the presence of naturally-occurring radionuclides in building materials. Some of the consumer product sources contribute exposure mainly to localized tissues or organs. Such localized estimates include: 0.5 to 1 mrem to the average annual population lung dose equivalent (generalized); 2 rem to the average annual population bronchial epithelial dose equivalent (localized); and 10 to 15 rem to the average annual population basal mucosal dose equivalent (basal mucosa of the gum). Based on these estimates, these sources may be grouped or classified as those that involve many people and the dose equivalent is relative large or those that involve many people but the dose equivalent is relatively small, or the dose equivalent is relatively large but the number of people involved is small.« less

Analysis of multi-layered films. [determining dye densities by applying a regression analysis to the spectral response of the composite transparency

NASA Technical Reports Server (NTRS)

Scarpace, F. L.; Voss, A. W.

1973-01-01

Dye densities of multi-layered films are determined by applying a regression analysis to the spectral response of the composite transparency. The amount of dye in each layer is determined by fitting the sum of the individual dye layer densities to the measured dye densities. From this, dye content constants are calculated. Methods of calculating equivalent exposures are discussed. Equivalent exposures are a constant amount of energy over a limited band-width that will give the same dye content constants as the real incident energy. Methods of using these equivalent exposures for analysis of photographic data are presented.

Exposure to BTEX and Ethers in Petrol Station Attendants and Proposal of Biological Exposure Equivalents for Urinary Benzene and MTBE.

PubMed

Campo, Laura; Rossella, Federica; Mercadante, Rosa; Fustinoni, Silvia

2016-04-01

To assess exposure to benzene (BEN) and other aromatic compounds (toluene, ethylbenzene, m+p-xylene, o-xylene) (BTEX), methyl tert-butyl ether (MTBE), and ethyl tert-butyl ether (ETBE) in petrol station workers using air sampling and biological monitoring and to propose biological equivalents to occupational limit values. Eighty-nine petrol station workers and 90 control subjects were investigated. Personal exposure to airborne BTEX and ethers was assessed during a mid-week shift; urine samples were collected at the beginning of the work week, prior to and at the end of air sampling. Petrol station workers had median airborne exposures to benzene and MTBE of 59 and 408 µg m(-3), respectively, with urinary benzene (BEN-U) and MTBE (MTBE-U) of 339 and 780 ng l(-1), respectively. Concentrations in petrol station workers were higher than in control subjects. There were significant positive correlations between airborne exposure and the corresponding biological marker, with Pearson's correlation coefficient (r) values of 0.437 and 0.865 for benzene and MTBE, respectively. There was also a strong correlation between airborne benzene and urinary MTBE (r = 0.835). Multiple linear regression analysis showed that the urinary levels of benzene were influenced by personal airborne exposure, urinary creatinine, and tobacco smoking [determination coefficient (R(2)) 0.572], while MTBE-U was influenced only by personal exposure (R(2) = 0.741). BEN-U and MTBE-U are sensitive and specific biomarkers of low occupational exposures. We propose using BEN-U as biomarker of exposure to benzene in nonsmokers and suggest 1457 ng l(-1) in end shift urine samples as biological exposure equivalent to the EU occupational limit value of 1 p.p.m.; for both smokers and nonsmokers, MTBE-U may be proposed as a surrogate biomarker of benzene exposure, with a biological exposure equivalent of 22 µg l(-1) in end shift samples. For MTBE exposure, we suggest the use of MTBE-U with a biological exposure equivalent of 22 µg l(-1) corresponding to the occupational limit value of 50 p.p.m. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Noise exposure estimates of urban MP3 player users.

PubMed

Levey, Sandra; Levey, Tania; Fligor, Brian J

2011-02-01

To examine the sound level and duration of use of personal listening devices (PLDs) by 189 college students, ages 18-53 years, as they entered a New York City college campus, to determine whether noise exposure from PLDs was in excess of recommended exposure limits and what factors might influence exposure. Free-field equivalent sound levels from PLD headphones were measured on a mannequin with a calibrated sound level meter. Participants reported demographic information, whether they had just come off the subway, the type of PLD and earphones used, and duration per day and days per week they used their PLDs. Based on measured free-field equivalent sound levels from PLD headphones and the reported PLD use, per day 58.2% of participants exceeded 85 dB A-weighted 8-hr equivalent sound levels (L(Aeq)), and per week 51.9% exceeded 85 dB A-weighted 40-hr equivalent continuous sound levels (L(Awkn)). The majority of PLD users exceeded recommended sound exposure limits, suggesting that they were at increased risk for noise-induced hearing loss. Analyses of the demographics of these participants and mode of transportation to campus failed to indicate any particular gender differences in PLD use or in mode of transportation influencing sound exposure.

Shielding from Solar Particle Event Exposures in Deep Space

NASA Technical Reports Server (NTRS)

Wilson, John W.; Cucinotta, F. A.; Shinn, J. L.; Simonsen, L. C.; Dubey, R. R.; Jordan, W. R.; Jones, T. D.; Chang, C. K.; Kim, M. Y.

1999-01-01

The physical composition and intensities of solar particle event exposures or sensitive astronaut tissues are examined under conditions approximating an astronaut in deep space. Response functions for conversion of particle fluence into dose and dose equivalent averaged over organ tissue, are used to establish significant fluence levels and the expected dose and dose rates of the most important events from past observations. The BRYNTRN transport code is used to evaluate the local environment experienced by sensitive tissues and used to evaluate bioresponse models developed for use in tactical nuclear warfare. The present results will help to the biophysical aspects of such exposure in the assessment of RBE and dose rate effects and their impact on design of protection systems for the astronauts. The use of polymers as shielding material in place of an equal mass of aluminum would prowide a large safety factor without increasing the vehicle mass. This safety factor is sufficient to provide adequate protection if a factor of two larger event than has ever been observed in fact occurs during the mission.

Racial/ethnic harassment and discrimination, its antecedents, and its effect on job-related outcomes.

PubMed

Bergman, Mindy E; Palmieri, Patrick A; Drasgow, Fritz; Ormerod, Alayne J

2012-01-01

A general model of workplace prejudice acts, their antecedents, and their consequences is proposed and examined in the context of racial/ethnic harassment and discrimination (REHD). Antecedents proposed and tested here include context and climate, whereas consequences proposed and tested here include work, supervisor, and opportunity satisfaction and turnover intentions. The theoretical model is first tested and cross-validated in two ethnically diverse subsamples (approximately 2,000 each). Then, hierarchical multigroup modeling was conducted to determine whether the relationships among REHD, its antecedents, and its outcomes are equivalent across five racial/ethnic groups (N = 1,000 per group) in the U.S. military. This addresses the issue of differential exposure (i.e., varying amounts of stressors across groups) versus differential vulnerability (i.e., discrepant impact of a stressor on outcomes across groups) across racial/ethnic groups. Consistent with expectations, results suggest that although racial/ethnic groups differ in their mean exposure to REHD, the relationships among REHD and its outcomes are the same across race/ethnicity, supporting the differential exposure view. In addition, the results show some differences between antecedents and REHD across race/ethnicity.

Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

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

Carl, W. F.

NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

Use of equivalent spheres to model the relation between radar reflectivity and optical extinction of ice cloud particles.

PubMed

Donovan, David Patrick; Quante, Markus; Schlimme, Ingo; Macke, Andreas

2004-09-01

The effect of ice crystal size and shape on the relation between radar reflectivity and optical extinction is examined. Discrete-dipole approximation calculations of 95-GHz radar reflectivity and ray-tracing calculations are applied to ice crystals of various habits and sizes. Ray tracing was used primarily to calculate optical extinction and to provide approximate information on the lidar backscatter cross section. The results of the combined calculations are compared with Mie calculations applied to collections of different types of equivalent spheres. Various equivalent sphere formulations are considered, including equivalent radar-lidar spheres; equivalent maximum dimension spheres; equivalent area spheres, and equivalent volume and equivalent effective radius spheres. Marked differences are found with respect to the accuracy of different formulations, and certain types of equivalent spheres can be used for useful prediction of both the radar reflectivity at 95 GHz and the optical extinction (but not lidar backscatter cross section) over a wide range of particle sizes. The implications of these results on combined lidar-radar ice cloud remote sensing are discussed.

Ethanol exposure during the early first trimester equivalent impairs reflexive motor activity and heightens fearfulness in an avian model.

PubMed

Smith, Susan M; Flentke, George R; Kragtorp, Katherine A; Tessmer, Laura

2011-02-01

Prenatal alcohol exposure is a leading cause of childhood neurodevelopmental disability. The adverse behavioral effects of alcohol exposure during the second and third trimester are well documented; less clear is whether early first trimester-equivalent exposures also alter behavior. We investigated this question using an established chick model of alcohol exposure. In ovo embryos experienced a single, acute ethanol exposure that spanned gastrulation through neuroectoderm induction and early brain patterning (19-22h incubation). At 7 days posthatch, the chicks were evaluated for reflexive motor function (wingflap extension, righting reflex), fearfulness (tonic immobility [TI]), and fear/social reinstatement (open-field behavior). Chicks exposed to a peak ethanol level of 0.23-0.28% were compared against untreated and saline-treated controls. Birds receiving early ethanol exposure had a normal righting reflex and a significantly reduced wingflap extension in response to a sudden descent. The ethanol-treated chicks also displayed heightened fearfulness, reflected in increased frequency of TI, and they required significantly fewer trials for its induction. In an open-field test, ethanol treatment did not affect latency to move, steps taken, vocalizations, defecations, or escape attempts. The current findings demonstrate that early ethanol exposure can increase fearfulness and impair aspects of motor function. Importantly, the observed dysfunctions resulted from an acute ethanol exposure during the period when the major brain components are induced and patterned. The equivalent period in human development is 3-4 weeks postconception. The current findings emphasize that ethanol exposure during the early first trimester equivalent can produce neurodevelopmental disability in the offspring. Copyright © 2011 Elsevier Inc. All rights reserved.

CORROSION EXPERIENCE WITH ALUMINUM POWDER PRODUCTS

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

Draley, J.E.; Ruther, W.E.; Greenberg, S.

1963-11-01

Extrusions of aluminum alloy powder products were obtained from several sources and evaluated for corrosion resistance to high-temperature (260-- 350 deg C) water. Several types of tubing impact-extruded by ALCOA were tested. The stronger tabing (M655) failed very rapidly. The weaker tubing suffered extensive localized surface attack and penetration of the corrosion attack along the extrusion direction after prolonged ( approximates 3 months) exposure to 290 deg C water. A precorrosion heat treatment was effective in reducing both types of attack on the weaker tubing. Armour Research Foundation supplied several types of tubing extraded through a bridge die. All tubesmore » failed on prolonged ( approximates 8 months) corrosion in 290 deg C water at the longitudinal bond lines. These lines were formed by the rejoining of the metal streams passing over the mandrel supports in the die during extrusion. Directly extruded tubing supplied by the Torrance Brass Company also failed on extended exposure to 290 deg C water. Many experimental rod extrusions (from Armour Research Foundation and Trefimetaux) exhibited corrosion resistance to static 290 deg C water equivalent to that of wrought alloys. The Trefimetaux specimens were also tested in rapidly flowing water at 315 deg C. Under these conditions a corrosion rate significantly faster than for the wrought alloy was measured. (auth)« less

Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

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

Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.

We performed a systematic intercomparison study of the chemistry and yields of secondary organic aerosol (SOA) generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0 × 10 8 to 2.2 × 10 10 molec cm -3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 10 6 to 2 × 10 7 molec cm -3 over exposure times of severalmore » hours. The OH concentration in the chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. In most cases, for a specific SOA type the most-oxidized chamber SOA and the least-oxidized flow reactor SOA have similar mass spectra, oxygen-to-carbon and hydrogen-to-carbon ratios, and carbon oxidation states at integrated OH exposures between approximately 1 × 10 11 and 2 × 10 11 molec cm -3 s, or about 1–2 days of equivalent atmospheric oxidation. This observation suggests that in the range of available OH exposure overlap for the flow reactor and chambers, SOA elemental composition as measured by an aerosol mass spectrometer is similar whether the precursor is exposed to low OH concentrations over long exposure times or high OH concentrations over short exposure times. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed particles are routinely used.« less

Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

DOE PAGES

Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.; ...

2015-03-18

We performed a systematic intercomparison study of the chemistry and yields of secondary organic aerosol (SOA) generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0 × 10 8 to 2.2 × 10 10 molec cm -3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 10 6 to 2 × 10 7 molec cm -3 over exposure times of severalmore » hours. The OH concentration in the chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. In most cases, for a specific SOA type the most-oxidized chamber SOA and the least-oxidized flow reactor SOA have similar mass spectra, oxygen-to-carbon and hydrogen-to-carbon ratios, and carbon oxidation states at integrated OH exposures between approximately 1 × 10 11 and 2 × 10 11 molec cm -3 s, or about 1–2 days of equivalent atmospheric oxidation. This observation suggests that in the range of available OH exposure overlap for the flow reactor and chambers, SOA elemental composition as measured by an aerosol mass spectrometer is similar whether the precursor is exposed to low OH concentrations over long exposure times or high OH concentrations over short exposure times. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed particles are routinely used.« less

76 FR 76698 - Dominion Cove Point LNG, LP; Application To Export Domestic Liquefied Natural Gas to Non-Free...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-08

... Domestic Liquefied Natural Gas to Non-Free Trade Agreement Nations AGENCY: Office of Fossil Energy, DOE... metric tons per year of domestically produced liquefied natural gas (LNG) (equivalent to approximately... equivalent to approximately 1 Bcf per day of natural gas. DATES: Protests, motions to intervene or notices of...

Effects of oxide additions and temperature on sinterability of milled silicon nitride

NASA Technical Reports Server (NTRS)

Arias, A.

1980-01-01

Specimens of milled alpha-Si3N4 with 0 to 5.07 equivalent percent of oxide additions were pressureless sintered at 1650 to 1820 C for 4 hours in nitrogen while covered with powdered Si3N4 + SiO2. Densities of less than or equal to 97.5 percent resulted with approximately 2.5 equivalent percent of MgO, CeO2, Y2O3, and three mixtures involving these oxides. Densities of greater than or equal to 94 percent were obtained with approximately 0.62 equivalent percent of the same additives. At most temperatures, best sinterability (density maxima) was obtained with 1.2 to 2.5 equivalent percent additive.

The Concept of Equivalent Radon Concentration for Practical Consideration of Indoor Exposure to Thoron

PubMed Central

Chen, Jing; Moir, Deborah

2012-01-01

To consider the total exposure to indoor radon and thoron, a concept of equivalent radon concentration for thoron is introduced, defined as the radon concentration that delivers the same annual effective dose as that resulting from the thoron concentration. The total indoor exposure to radon and thoron is then the sum of the radon concentration and the equivalent radon concentration for thoron. The total exposure should be compared to the radon guideline value, and if it exceeds the guideline value, appropriate remedial action is required. With this concept, a separate guideline for indoor thoron exposure is not necessary. For homes already tested for radon with radon detectors, Health Canada’s recommendation of a 3-month radon test performed during the fall/winter heating season not only ensures a conservative estimate of the annual average radon concentration but also covers well any potentially missing contribution from thoron exposure. In addition, because the thoron concentration is much lower than the radon concentration in most homes in Canada, there is no real need to re-test homes for thoron. PMID:22470292

Approximate Simulation of Acute Hypobaric Hypoxia with Normobaric Hypoxia

NASA Technical Reports Server (NTRS)

Conkin, J.; Wessel, J. H., III

2011-01-01

INTRODUCTION. Some manufacturers of reduced oxygen (O2) breathing devices claim a comparable hypobaric hypoxia (HH) training experience by providing F(sub I) O2 < 0.209 at or near sea level pressure to match the ambient O2 partial pressure (iso-pO2) of the target altitude. METHODS. Literature from investigators and manufacturers indicate that these devices may not properly account for the 47 mmHg of water vapor partial pressure that reduces the inspired partial pressure of O2 (P(sub I) O2). Nor do they account for the complex reality of alveolar gas composition as defined by the Alveolar Gas Equation. In essence, by providing iso-pO2 conditions for normobaric hypoxia (NH) as for HH exposures the devices ignore P(sub A)O2 and P(sub A)CO2 as more direct agents to induce signs and symptoms of hypoxia during acute training exposures. RESULTS. There is not a sufficient integrated physiological understanding of the determinants of P(sub A)O2 and P(sub A)CO2 under acute NH and HH given the same hypoxic pO2 to claim a device that provides isohypoxia. Isohypoxia is defined as the same distribution of hypoxia signs and symptoms under any circumstances of equivalent hypoxic dose, and hypoxic pO2 is an incomplete hypoxic dose. Some devices that claim an equivalent HH experience under NH conditions significantly overestimate the HH condition, especially when simulating altitudes above 10,000 feet (3,048 m). CONCLUSIONS. At best, the claim should be that the devices provide an approximate HH experience since they only duplicate the ambient pO2 at sea level as at altitude (iso-pO2 machines). An approach to reduce the overestimation is to at least provide machines that create the same P(sub I)O2 (iso-P(sub I)O2 machines) conditions at sea level as at the target altitude, a simple software upgrade.

Identifying populations sensitive to environmental chemicals by simulating toxicokinetic variability.

PubMed

Ring, Caroline L; Pearce, Robert G; Setzer, R Woodrow; Wetmore, Barbara A; Wambaugh, John F

2017-09-01

The thousands of chemicals present in the environment (USGAO, 2013) must be triaged to identify priority chemicals for human health risk research. Most chemicals have little of the toxicokinetic (TK) data that are necessary for relating exposures to tissue concentrations that are believed to be toxic. Ongoing efforts have collected limited, in vitro TK data for a few hundred chemicals. These data have been combined with biomonitoring data to estimate an approximate margin between potential hazard and exposure. The most "at risk" 95th percentile of adults have been identified from simulated populations that are generated either using standard "average" adult human parameters or very specific cohorts such as Northern Europeans. To better reflect the modern U.S. population, we developed a population simulation using physiologies based on distributions of demographic and anthropometric quantities from the most recent U.S. Centers for Disease Control and Prevention National Health and Nutrition Examination Survey (NHANES) data. This allowed incorporation of inter-individual variability, including variability across relevant demographic subgroups. Variability was analyzed with a Monte Carlo approach that accounted for the correlation structure in physiological parameters. To identify portions of the U.S. population that are more at risk for specific chemicals, physiologic variability was incorporated within an open-source high-throughput (HT) TK modeling framework. We prioritized 50 chemicals based on estimates of both potential hazard and exposure. Potential hazard was estimated from in vitro HT screening assays (i.e., the Tox21 and ToxCast programs). Bioactive in vitro concentrations were extrapolated to doses that produce equivalent concentrations in body tissues using a reverse dosimetry approach in which generic TK models are parameterized with: 1) chemical-specific parameters derived from in vitro measurements and predicted from chemical structure; and 2) with physiological parameters for a virtual population. For risk-based prioritization of chemicals, predicted bioactive equivalent doses were compared to demographic-specific inferences of exposure rates that were based on NHANES urinary analyte biomonitoring data. The inclusion of NHANES-derived inter-individual variability decreased predicted bioactive equivalent doses by 12% on average for the total population when compared to previous methods. However, for some combinations of chemical and demographic groups the margin was reduced by as much as three quarters. This TK modeling framework allows targeted risk prioritization of chemicals for demographic groups of interest, including potentially sensitive life stages and subpopulations. Published by Elsevier Ltd.

The long-term decrease of 90Sr availability in the environment and its transfer to man after a nuclear fallout.

PubMed

Mück, K; Sinojmeri, M; Whilidal, H; Steger, F

2001-01-01

Due to its long physical half-life, and the fact that its long-term mobility in the environment as well as its radiotoxicity is higher than that of 137Cs, the long-term bio-availability of 90Sr in the environment is of importance with regard to the long-term population exposure after fallout from nuclear weapons detonations or a severe reactor accident. It will also substantially influence the time-span required until re-utilisation of highly contaminated territory is possible again. An assessment of the long-term decrease of the activity concentration in all foodstuffs relevant for internal exposure after severe 90Sr fallout was performed. The observed effective half-lives were approximately 1.8-2.1 years in the first 2-3 years after the end of fallout and 8-10 years in the following three decades. This is equivalent to a biological half-life of about 13.2 years and results in a total 50 year dose of 6.2 times the first year exposure. Due to this decline in 90Sr-availability, the average annual activity intake of 90Sr in Austria has decreased from 840 Bq at the climax of the nuclear weapons tests to about 42 Bq in 1997 for adults, and from 500 Bq to about 35 Bq for 1 year old infants. This is equivalent to a 90Sr ingestion dose of 1.2 microSv for adults and 2.5 microSv for 1 year old infants in 1997 or less than 0.4% of the ingestion dose by natural radionuclides in the diet.

Absorption and scattering by fractal aggregates and by their equivalent coated spheres

NASA Astrophysics Data System (ADS)

Kandilian, Razmig; Heng, Ri-Liang; Pilon, Laurent

2015-01-01

This paper demonstrates that the absorption and scattering cross-sections and the asymmetry factor of randomly oriented fractal aggregates of spherical monomers can be rapidly estimated as those of coated spheres with equivalent volume and average projected area. This was established for fractal aggregates with fractal dimension ranging from 2.0 to 3.0 and composed of up to 1000 monodisperse or polydisperse monomers with a wide range of size parameter and relative complex index of refraction. This equivalent coated sphere approximation was able to capture the effects of both multiple scattering and shading among constituent monomers on the integral radiation characteristics of the aggregates. It was shown to be superior to the Rayleigh-Debye-Gans approximation and to the equivalent coated sphere approximation proposed by Latimer. However, the scattering matrix element ratios of equivalent coated spheres featured large angular oscillations caused by internal reflection in the coating which were not observed in those of the corresponding fractal aggregates. Finally, the scattering phase function and the scattering matrix elements of aggregates with large monomer size parameter were found to have unique features that could be used in remote sensing applications.

Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour.

PubMed

Martin, T L; Coe, C; Bagot, P A J; Morrall, P; Smith, G D W; Scott, T; Moody, M P

2016-07-12

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour.

Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour

NASA Astrophysics Data System (ADS)

Martin, T. L.; Coe, C.; Bagot, P. A. J.; Morrall, P.; Smith, G. D. W.; Scott, T.; Moody, M. P.

2016-07-01

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour.

Changes in the Optical Properties of Simulated Shuttle Waste Water Deposits: Urine Darkening

NASA Technical Reports Server (NTRS)

Albyn, Keith; Edwards, David; Alred, John

2003-01-01

Manned spacecraft have historically dumped the crew generated waste water overboard, into the environment in which the spacecraft operates, sometimes depositing the waste water on the external spacecraft surfaces. The change in optical properties of wastewater deposited on spacecraft external surfaces, from exposure to space environmental effects, is not well understood. This study used nonvolatile residue (NVR) from Human Urine to simulate wastewater deposits and documents the changes in the optical properties of the NVR deposits after exposure to ultra violet(UV)radiation. Twenty four NVR samples of, 0-angstromes/sq cm to 1000-angstromes/sq cm, and one sample contaminated with 1 to 2-mg/sq cm were exposed to UV radiation over the course of approximately 6151 equivalent sun hours (ESH). Random changes in sample mass, NVR, solar absorbance, and infrared emission were observed during the study. Significant changes in the UV transmittance were observed for one sample contaminated at the mg/sq cm level.

Changes in the Optical Properties of Simulated Shuttle Waste Water Deposits- Urine Darkening

NASA Technical Reports Server (NTRS)

Albyn, Keith; Edwards, David; Alred, John

2004-01-01

Manned spacecraft have historically dumped the crew generated waste waster overboard, into the environment in which the spacecraft operates, sometimes depositing the waste water on the external spacecraft surfaces. The change in optical properties of wastewater deposited on spacecraft external surfaces, from exposure to space environmental effects, is not well understood. This study used nonvolatile residue (NVR) from Human Urine to simulate wastewater deposits and documents the changes in the optical properties of the NVR deposits after exposure to ultra violet (UV) radiation. Twenty NVR samples of, 0-angstromes/sq cm to 1000-angstromes/sq cm, and one sample contaminated with 1 to 2-mg/sq cm were exposed to UV radiation over the course of approximately 6151 equivalent sun hours (ESH). Random changes in sample mass, NVR, solar absorbance, and infrared emission were observed during the study. Significant changes in the UV transmittance were observed for one sample contaminated at the mg/sq cm level.

Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour

PubMed Central

Martin, T. L.; Coe, C.; Bagot, P. A. J.; Morrall, P.; Smith, G. D. W; Scott, T.; Moody, M. P.

2016-01-01

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour. PMID:27403638

Sharps Injuries and Other Blood and Body Fluid Exposures Among Home Health Care Nurses and Aides

PubMed Central

Markkanen, Pia K.; Galligan, Catherine J.; Kriebel, David; Chalupka, Stephanie M.; Kim, Hyun; Gore, Rebecca J.; Sama, Susan R.; Laramie, Angela K.; Davis, Letitia

2009-01-01

Objectives. We quantified risks of sharp medical device (sharps) injuries and other blood and body fluid exposures among home health care nurses and aides, identified risk factors, assessed the use of sharps with safety features, and evaluated underreporting in workplace-based surveillance. Methods. We conducted a questionnaire survey and workplace-based surveillance, collaborating with 9 home health care agencies and 2 labor unions from 2006 to 2007. Results. Approximately 35% of nurses and 6.4% of aides had experienced at least 1 sharps injury during their home health care career; corresponding figures for other blood and body fluid exposures were 15.1% and 6.7%, respectively. Annual sharps injuries incidence rates were 5.1 per 100 full-time equivalent (FTE) nurses and 1.0 per 100 FTE aides. Medical procedures contributing to sharps injuries were injecting medications, administering fingersticks and heelsticks, and drawing blood. Other contributing factors were sharps disposal, contact with waste, and patient handling. Sharps with safety features frequently were not used. Underreporting of sharps injuries to the workplace-based surveillance system was estimated to be about 50%. Conclusions. Sharps injuries and other blood and body fluid exposures are serious hazards for home health care nurses and aides. Improvements in hazard intervention are needed. PMID:19890177

Hearing in young adults. Part II: The effects of recreational noise exposure

PubMed Central

Keppler, Hannah; Dhooge, Ingeborg; Vinck, Bart

2015-01-01

Great concern arises from recreational noise exposure, which might lead to noise-induced hearing loss in young adults. The objective of the current study was to evaluate the effects of recreational noise exposure on hearing function in young adults. A questionnaire concerning recreational noise exposures and an audiological test battery were completed by 163 subjects (aged 18-30 years). Based on the duration of exposure and self-estimated loudness of various leisure-time activities, the weekly and lifetime equivalent noise exposure were calculated. Subjects were categorized in groups with low, intermediate, and high recreational noise exposure based on these values. Hearing was evaluated using audiometry, transient-evoked otoacoustic emissions (TEOAEs), and distortion-product otoacoustic emissions (DPOAEs). Mean differences in hearing between groups with low, intermediate, and high recreational noise exposure were evaluated using one-way analysis of variance (ANOVA). There were no significant differences in hearing thresholds, TEOAE amplitudes, and DPOAE amplitudes between groups with low, intermediate, or high recreational noise exposure. Nevertheless, one-third of our subjects exceeded the weekly equivalent noise exposure for all activities of 75 dBA. Further, the highest equivalent sound pressure levels (SPLs) were calculated for the activities visiting nightclubs or pubs, attending concerts or festivals, and playing in a band or orchestra. Moreover, temporary tinnitus after recreational noise exposure was found in 86% of our subjects. There were no significant differences in hearing between groups with low, intermediate, and high recreational noise exposure. Nevertheless, a long-term assessment of young adults’ hearing in relation to recreational noise exposure is needed. PMID:26356366

Products and mechanisms of the reaction of gas phase ozone with organic colorants

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

Grosjean, D.; Druzik, J.R.; Sensharma, D.K.

1988-09-01

Studies carried out in this laboratory have shown that many artists organic colorants fade substantially when exposed to ozone in the dark. These studies typically involved pigment exposure for 12 weeks to purified air containing 0.3-0.4 ppm of ozone at ambient temperature and humidity. These laboratory conditions are equivalent to about six years of exposure inside a typical air-conditioned building in Los Angeles, and the observed fading is therefore directly relevant to possible damage to works of arts in museum settings. Organic colorants that were most ozone-fugitive included natural colorants, such as curcumin and indigo, as well as modern syntheticmore » colorants such as alizarin lakes and triphenylmethane dyes. Thus, these colorants were selected for further study with emphasis on the nature of the reaction products. Exposures were carried out on different substrates including watercolor paper, cellulose, silica gel, and Teflon. The experiments involved long-term exposure to low levels of ozone (e.g. {approximately} 0.3 ppm for 90 days) or shorter-term exposure to higher ozone concentrations (e.g. 10 ppm for 24 hours). Exposed and control samples, along with solvent and substrate blanks, were analyzed by mass spectrometry using a Kratos Scientific Instruments MS25 hexapole mass spectrometer operated in either methane chemical ionization (CI) or electron impact (EI) modes.« less

Vitamin D and skin physiology: a D-lightful story.

PubMed

Holick, Michael F; Chen, Tai C; Lu, Zhiren; Sauter, Edward

2007-12-01

Throughout evolution, exposure to sunlight and the photosynthesis of vitamin D(3) in the skin has been critically important for the evolution of land vertebrates. During exposure to sunlight, the solar UVB photons with energies 290-315 nm are absorbed by 7-dehydrocholesterol in the skin and converted to previtamin D(3). Previtamin D(3) undergoes a rapid transformation within the plasma membrane to vitamin D(3). Excessive exposure to sunlight will not result in vitamin D intoxication because both previtamin D(3) and vitamin D(3) are photolyzed to several noncalcemic photoproducts. During the winter at latitudes above approximately 35 degrees , there is minimal, if any, previtamin D(3) production in the skin. Altitude also has a significant effect on vitamin D(3) production. At 27 degrees N in November, very little ( approximately 0.5%) previtamin D(3) synthesis was detected in Agra (169 m) and Katmandu (1400 m). There was an approximately 2- and 4-fold increase in previtamin D(3) production at approximately 3400 m and at Everest base camp (5300 m), respectively. Increased skin pigmentation, application of a sunscreen, aging, and clothing have a dramatic effect on previtamin D(3) production in the skin. It is estimated that exposure in a bathing suit to 1 minimal erythemal dose (MED) is equivalent to ingesting between 10,000 and 25,000 IU of vitamin D(2). The importance of sunlight for providing most humans with their vitamin D requirement is well documented by the seasonal variation in circulating levels of 25-hydroxyvitamin D [25(OH)D]. Vitamin D deficiency [i.e., 25(OH)D < 20 ng/ml] is common in both children and adults worldwide. Exposure to lamps that produce UVB radiation is an excellent source for producing vitamin D(3) in the skin and is especially efficacious in patients with fat malabsorption syndromes. The major cause of vitamin D deficiency globally is an underappreciation of sunlight's role in providing humans with their vitamin D(3) requirement. Very few foods naturally contain vitamin D, and those that do have a very variable vitamin D content. Recently it was observed that wild caught salmon had between 75% and 90% more vitamin D(3) compared with farmed salmon. The associations regarding increased risk of common deadly cancers, autoimmune diseases, infectious diseases, and cardiovascular disease with living at higher latitudes and being prone to vitamin D deficiency should alert all health care professionals about the importance of vitamin D for overall health and well being.

An approximate method for solution to variable moment of inertia problems

NASA Technical Reports Server (NTRS)

Beans, E. W.

1981-01-01

An approximation method is presented for reducing a nonlinear differential equation (for the 'weather vaning' motion of a wind turbine) to an equivalent constant moment of inertia problem. The integrated average of the moment of inertia is determined. Cycle time was found to be the equivalent cycle time if the rotating speed is 4 times greater than the system's minimum natural frequency.

MTBE inhaled alone and in combination with gasoline vapor: uptake, distribution, metabolism, and excretion in rats.

PubMed

Benson, J M; Barr, E B; Krone, J R

2001-05-01

The purpose of these studies was to extend previous evaluation of methyl tert-butyl ether (MTBE)* tissue distribution, metabolism, and excretion in rats to include concentrations more relevant to human exposure (4 and 40 ppm) and to determine the effects of coinhalation of the volatile fraction of unleaded gasoline on the tissue distribution, metabolism, and excretion of MTBE. Groups of male F344 rats were exposed nose-only for 4 hours to 4, 40, or 400 ppm 14C-MTBE or to 20 or 200 ppm of the light fraction of unleaded gasoline (LFG) containing 4 or 40 ppm 14C-MTBE, respectively. To evaluate the effects of repeated inhalation of LFG on MTBE tissue distribution, metabolism, and excretion, rats were exposed for 4 hours on each of 7 consecutive days to 20 or 200 ppm LFG with MTBE (4 or 40 ppm) followed on the eighth day by a similar exposure to LFG containing 14C-MTBE. Subgroups of rats were evaluated for respiratory parameters, initial body burdens, rates and routes of excretion, and tissue distribution and elimination. The concentrations of MTBE and its chief metabolite, tert-butyl alcohol (TBA), were measured in blood and kidney immediately after exposure, and the major urinary metabolites-2-hydroxyisobutyric acid (IBA) and 2-methyl-1,2-propanediol (2MePD)-were measured in urine. Inhalation of MTBE alone or as a component of LFG had no concentration-dependent effect on respiratory minute volume. The initial body burdens of MTBE equivalents achieved after 4 hours of exposure to MTBE did not increase linearly with exposure concentration. MTBE equivalents rapidly distributed to all tissues examined, with the largest percentages distributed to liver. The observed initial body burden did not increase linearly between 4 and 400 ppm. At 400 ppm, elimination half-times of MTBE equivalents from liver increased and from lung, kidney, and testes decreased compared with the two smaller doses. Furthermore, at 400 ppm the elimination half-time for volatile organic compounds (VOCs) in breath was significantly shorter and the percentage of the initial body burden of MTBE equivalents eliminated as VOCs in breath increased significantly. These changes probably reflect a saturation of blood with MTBE at 400 ppm and strongly suggest that the uptake and fate of MTBE are notably different at exposure concentrations above and below 400 ppm. Single and repeated coexposure to 20 and 200 ppm LFG with MTBE had opposite effects on the total body burden of MTBE equivalents present at the end of exposures compared with those achieved after 4 and 40 ppm MTBE exposures: 20 ppm LFG increased and 200 ppm LFG significantly decreased the burdens of MTBE equivalents present. The effects of coexposure to LFG on blood levels of MTBE equivalents paralleled the effects on body burden. These differences in overall uptake of MTBE equivalents cannot be attributed to alterations of minute volume. The reason for the increase in overall uptake after 20-ppm LFG exposure is not clear. Decreased MTBE absorption (uptake) after single and repeated coexposure to 200 ppm LFG may be due to a decrease in solubility of MTBE in blood caused by inhalation of other hydrocarbons. Investigations on the blood/air partition coefficient of MTBE in the absence and presence of LFG would be needed to confirm this hypothesis. Single and repeated coexposure to either 20 or 200 ppm LFG significantly decreased the percentage of the initial body burden from MTBE equivalents in tissues, including liver, kidney, and testes, immediately and 72 hours after

Noise and low-frequency sound levels due to aerial fireworks and prediction of the occupational exposure of pyrotechnicians to noise

PubMed Central

Tanaka, Tagayasu; Inaba, Ryoichi; Aoyama, Atsuhito

2016-01-01

Objectives: This study investigated the actual situation of noise and low-frequency sounds in firework events and their impact on pyrotechnicians. Methods: Data on firework noise and low-frequency sounds were obtained at a point located approximately 100 m away from the launch site of a firework display held in "A" City in 2013. We obtained the data by continuously measuring and analyzing the equivalent continuous sound level (Leq) and the one-third octave band of the noise and low-frequency sounds emanating from the major firework detonations, and predicted sound levels at the original launch site. Results: Sound levels of 100-115 dB and low-frequency sounds of 100-125 dB were observed at night. The maximum and mean Leq values were 97 and 95 dB, respectively. The launching noise level predicted from the sounds (85 dB) at the noise measurement point was 133 dB. Occupational exposure to noise for pyrotechnicians at the remote operation point (located 20-30 m away from the launch site) was estimated to be below 100 dB. Conclusions: Pyrotechnicians are exposed to very loud noise (>100 dB) at the launch point. We believe that it is necessary to implement measures such as fixing earplugs or earmuffs, posting a warning at the workplace, and executing a remote launching operation to prevent hearing loss caused by occupational exposure of pyrotechnicians to noise. It is predicted that both sound levels and low-frequency sounds would be reduced by approximately 35 dB at the remote operation site. PMID:27725489

Noise and low-frequency sound levels due to aerial fireworks and prediction of the occupational exposure of pyrotechnicians to noise.

PubMed

Tanaka, Tagayasu; Inaba, Ryoichi; Aoyama, Atsuhito

2016-11-29

This study investigated the actual situation of noise and low-frequency sounds in firework events and their impact on pyrotechnicians. Data on firework noise and low-frequency sounds were obtained at a point located approximately 100 m away from the launch site of a firework display held in "A" City in 2013. We obtained the data by continuously measuring and analyzing the equivalent continuous sound level (Leq) and the one-third octave band of the noise and low-frequency sounds emanating from the major firework detonations, and predicted sound levels at the original launch site. Sound levels of 100-115 dB and low-frequency sounds of 100-125 dB were observed at night. The maximum and mean Leq values were 97 and 95 dB, respectively. The launching noise level predicted from the sounds (85 dB) at the noise measurement point was 133 dB. Occupational exposure to noise for pyrotechnicians at the remote operation point (located 20-30 m away from the launch site) was estimated to be below 100 dB. Pyrotechnicians are exposed to very loud noise (>100 dB) at the launch point. We believe that it is necessary to implement measures such as fixing earplugs or earmuffs, posting a warning at the workplace, and executing a remote launching operation to prevent hearing loss caused by occupational exposure of pyrotechnicians to noise. It is predicted that both sound levels and low-frequency sounds would be reduced by approximately 35 dB at the remote operation site.

Heavy ion contributions to organ dose equivalent for the 1977 galactic cosmic ray spectrum

NASA Astrophysics Data System (ADS)

Walker, Steven A.; Townsend, Lawrence W.; Norbury, John W.

2013-05-01

Estimates of organ dose equivalents for the skin, eye lens, blood forming organs, central nervous system, and heart of female astronauts from exposures to the 1977 solar minimum galactic cosmic radiation spectrum for various shielding geometries involving simple spheres and locations within the Space Transportation System (space shuttle) and the International Space Station (ISS) are made using the HZETRN 2010 space radiation transport code. The dose equivalent contributions are broken down by charge groups in order to better understand the sources of the exposures to these organs. For thin shields, contributions from ions heavier than alpha particles comprise at least half of the organ dose equivalent. For thick shields, such as the ISS locations, heavy ions contribute less than 30% and in some cases less than 10% of the organ dose equivalent. Secondary neutron production contributions in thick shields also tend to be as large, or larger, than the heavy ion contributions to the organ dose equivalents.

A Balloon Sounding Technique for Measuring SO2 Plumes

NASA Technical Reports Server (NTRS)

Morris, Gary A.; Komhyr, Walter D.; Hirokawa, Jun; Lefer, Barry; Krotkov, Nicholay; Ngan, Fong

2010-01-01

This paper reports on the development of a new technique for inexpensive measurements of SO2 profiles using a modified dual-ozonesonde instrument payload. The presence of SO2 interferes with the standard electrochemical cell (ECC) ozonesonde measurement, resulting in -1 molecule of O3 reported for each molecule of SO2 present (provided [O3] > [SO2]). In laboratory tests, an SO2 filter made with Cr03 placed on the inlet side of the sonde removes nearly 100% of the SO2 present for concentrations up to 60 ppbv and remained effective after exposure to 2.8 X 10(exp 16) molecules of SO2 [equivalent to a column approximately 150 DU (1 DU = 2.69 X 10(exp 20) molecules m(exp -2))]. Flying two ECC instruments on the same payload with one filtered and the other unfiltered yields SO2 profiles, inferred by subtraction. Laboratory tests and field experience suggest an SO2 detection limit of approximately 3 pbb with profiles valid from the surface to the ozonopause [i.e., approximately (8-10 km)]. Two example profiles demonstrate the success of this technique for both volcanic and industrial plumes.

In vitro effects of bicarbonate and bicarbonate-lactate buffered peritoneal dialysis solutions on mesothelial and neutrophil function.

PubMed

Topley, N; Kaur, D; Petersen, M M; Jörres, A; Williams, J D; Faict, D; Holmes, C J

1996-02-01

The inclusion of bicarbonate in the formulation of peritoneal dialysis solutions may avoid the in vitro impairment of certain cell functions seen with acidic lactate-based fluids. The supranormal physiological levels of HCO3- and PCO2 inherent in such formulations may, however, not be biocompatible. This study compared the in vitro biocompatibility of a pH 5.2 lactate-based formulation with formulations containing either 40 mM lactate at pH 7.4, 38 mM HCO3- at pH 6.8 (PCO2 at approximately 240 mm Hg) or 7.4 (PCO2 at approximately 60 mm Hg), and 25 mM HCO3- plus 15 mM lactate at pH 6.8 (PCO2 at approximately 160 mm Hg) or 7.4 (PCO2 at approximately 40 mm Hg). Significant release of lactate dehydrogenase or decreases in ATP content by human peritoneal mesothelial cells (HPMC) and human peripheral polymorphonuclear leukocytes (PMN) after a 30-min exposure to each test solution was only seen with the pH 5.2 lactate-based fluid. The ATP content of HPMC exposed to this fluid returned to control levels after 30 min of recovery in M199 control medium but showed a trend toward decreasing ATP content at 240 min. Similarly, interleukin (IL)-1 beta-induced IL-6 synthesis by HPMC was also only significantly reduced by the pH 5.2 lactate solution. PMN chemiluminescence was unaffected by 30-min exposure to all test solutions except for the pH 5.2 lactate formulation. Staphylococcus epidermidis phagocytosis was reduced to between 46 to 57% of control with all test solutions except the pH 5.2 lactate solution, which further suppressed the chemiluminescence response to 17% of control. These data suggest that short exposure to supranormal physiological levels of HCO3- and PCO2 does not impair HPMC or PMN viability and function. Furthermore, neutral pH lactate-containing solutions show equivalent biocompatibility to bicarbonate-based ones.

Micromolecular modeling

NASA Technical Reports Server (NTRS)

Guillet, J. E.

1984-01-01

A reaction kinetics based model of the photodegradation process, which measures all important rate constants, and a computerized model capable of predicting the photodegradation rate and failure modes of a 30 year period, were developed. It is shown that the computerized photodegradation model for polyethylene correctly predicts failure of ELVAX 15 and cross linked ELVAX 150 on outdoor exposure. It is indicated that cross linking ethylene vinyl acetate (EVA) does not significantly change its degradation rate. It is shown that the effect of the stabilizer package is approximately equivalent on both polymers. The computerized model indicates that peroxide decomposers and UV absorbers are the most effective stabilizers. It is found that a combination of UV absorbers and a hindered amine light stabilizer (HALS) is the most effective stabilizer system.

Time Averaged Transmitter Power and Exposure to Electromagnetic Fields from Mobile Phone Base Stations

PubMed Central

Bürgi, Alfred; Scanferla, Damiano; Lehmann, Hugo

2014-01-01

Models for exposure assessment of high frequency electromagnetic fields from mobile phone base stations need the technical data of the base stations as input. One of these parameters, the Equivalent Radiated Power (ERP), is a time-varying quantity, depending on communication traffic. In order to determine temporal averages of the exposure, corresponding averages of the ERP have to be available. These can be determined as duty factors, the ratios of the time-averaged power to the maximum output power according to the transmitter setting. We determine duty factors for UMTS from the data of 37 base stations in the Swisscom network. The UMTS base stations sample contains sites from different regions of Switzerland and also different site types (rural/suburban/urban/hotspot). Averaged over all regions and site types, a UMTS duty factor F ≈ 0.32 ± 0.08 for the 24 h-average is obtained, i.e., the average output power corresponds to about a third of the maximum power. We also give duty factors for GSM based on simple approximations and a lower limit for LTE estimated from the base load on the signalling channels. PMID:25105551

Thermal and physiologic responses to 1200-MHz radiofrequency radiation: Differences between exposure in E and H orientation

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

Jauchem, J.R.; Frei, M.R.; Padilla, J.M.

1990-09-01

Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 1200-MHz continuous wave radiofrequency radiation in both E and H orientations (long axis of animal parallel to electric or magnetic field, respectively). Power densities were used that resulted in equivalent whole-body specific absorption rates of approximately 8 W/kg in both orientations (20 mW/cm{sup 2} for E and 45 mW/cm{sup 2} for H). Exposure was conducted to repeatedly increase colonic temperature from 38.5 to 39.5{degrees}C in both orientations in the same animal. Irradiation in E orientation resulted in greater colonic, tympanic, left subcutaneous (side toward antenna), and tail heating. The results indicated a moremore » uniform distribution of heat than that which occurred in previous experiments of 2450-MHz irradiation in E and H orientation. A lack of significant differences in blood pressure and heart rate responses between exposures in the two orientations in this study suggest that greater peripheral heating, as was seen in the earlier study of 2450 MHz, is necessary for these differences to occur.« less

MUTZ-3 derived Langerhans cells in human skin equivalents show differential migration and phenotypic plasticity after allergen or irritant exposure

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

Kosten, Ilona J.; Spiekstra, Sander W.; Gruijl, Tanja D. de

After allergen or irritant exposure, Langerhans cells (LC) undergo phenotypic changes and exit the epidermis. In this study we describe the unique ability of MUTZ-3 derived Langerhans cells (MUTZ-LC) to display similar phenotypic plasticity as their primary counterparts when incorporated into a physiologically relevant full-thickness skin equivalent model (SE-LC). We describe differences and similarities in the mechanisms regulating LC migration and plasticity upon allergen or irritant exposure. The skin equivalent consisted of a reconstructed epidermis containing primary differentiated keratinocytes and CD1a{sup +} MUTZ-LC on a primary fibroblast-populated dermis. Skin equivalents were exposed to a panel of allergens and irritants. Topicalmore » exposure to sub-toxic concentrations of allergens (nickel sulfate, resorcinol, cinnamaldehyde) and irritants (Triton X-100, SDS, Tween 80) resulted in LC migration out of the epidermis and into the dermis. Neutralizing antibody to CXCL12 blocked allergen-induced migration, whereas anti-CCL5 blocked irritant-induced migration. In contrast to allergen exposure, irritant exposure resulted in cells within the dermis becoming CD1a{sup −}/CD14{sup +}/CD68{sup +} which is characteristic of a phenotypic switch of MUTZ-LC to a macrophage-like cell in the dermis. This phenotypic switch was blocked with anti-IL-10. Mechanisms previously identified as being involved in LC activation and migration in native human skin could thus be reproduced in the in vitro constructed skin equivalent model containing functional LC. This model therefore provides a unique and relevant research tool to study human LC biology in situ under controlled in vitro conditions, and will provide a powerful tool for hazard identification, testing novel therapeutics and identifying new drug targets. - Highlights: • MUTZ-3 derived Langerhans cells integrated into skin equivalents are fully functional. • Anti-CXCL12 blocks allergen-induced MUTZ-LC migration. • Anti-CCL5 blocks irritant-induced MUTZ-LC migration. • Irritant mediated MUTZ-LC trans-differentiation to macrophage-like cell in dermis. • Trans-differentiation of MUTZ-LC is IL-10 dependent.« less

A Novel Long-Acting Human Growth Hormone Fusion Protein (VRS-317): Enhanced In Vivo Potency and Half-Life

PubMed Central

Cleland, Jeffrey L; Geething, Nathan C; Moore, Jerome A; Rogers, Brian C; Spink, Benjamin J; Wang, Chai-Wei; Alters, Susan E; Stemmer, Willem P C; Schellenberger, Volker

2012-01-01

A novel recombinant human growth hormone (rhGH) fusion protein (VRS-317) was designed to minimize receptor-mediated clearance through a reduction in receptor binding without mutations to rhGH by genetically fusing with XTEN amino acid sequences to the N-terminus and the C-terminus of the native hGH sequence. Although in vitro potency of VRS-317 was reduced approximately 12-fold compared with rhGH, in vivo potency was increased because of the greatly prolonged exposure to the target tissues and organs. VRS-317 was threefold more potent than daily rhGH in hypophysectomized rats and fivefold more potent than daily rhGH in juvenile monkeys. In juvenile monkeys, a monthly dose of 1.4 mg/kg VRS-317 (equivalent to 0.26 mg/kg rhGH) caused a sustained pharmacodynamic response for 1 month equivalent to 0.05 mg/kg/day rhGH (1.4 mg/kg rhGH total over 28 days). In monkeys, VRS-317, having a terminal elimination half-life of approximately 110 h, was rapidly and near-completely absorbed, and was well tolerated with no observed adverse effects after every alternate week subcutaneous dosing for 14 weeks. VRS-317 also did not cause lipoatrophy in pig and monkey studies. VRS-317 is currently being studied in GH-deficient patients to confirm the observations in these animal studies. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:2744–2754, 2012 PMID:22678811

Radiation control in the intensive care unit for high intensity iridium-192 brain implants

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

Sewchand, W.; Drzymala, R.E.; Amin, P.P.

A bedside lead cubicle was designed to minimize the radiation exposure of intensive care unit staff during routine interstitial brain irradiation by removable, high intensity iridium-192. The cubicle shields the patient without restricting intensive care routines. The design specifications were confirmed by exposure measurements around the shield with an implanted anthropomorphic phantom simulating the patient situation. The cubicle reduces the exposure rate around an implant patient by as much as 90%, with the exposure level not exceeding 0.1 mR/hour/mg of radium-equivalent /sup 192/Ir. Evaluation of data accumulated for the past 3 years has shown that the exposure levels of individualmore » attending nurses are 0.12 to 0.36 mR/mg of radium-equivalent /sup 192/Ir per 12-hour shift. The corresponding range for entire nursing teams varies between 0.18 and 0.26. A radiation control index (exposure per mg of radium-equivalent /sup 192/Ir per nurse-hour) is thus defined for individual nurses and nursing teams; this index is a significant guide to the planning of nurse rotations for brain implant patients with various /sup 192/Ir loads. The bedside shield reduces exposure from /sup 192/Ir implants by a factor of about 20, as expected, and the exposure from the lower energy radioisotope iodine-125 is barely detectable.« less

Human cell exposure assays of Bacillus thuringiensis commercial insecticides: production of Bacillus cereus-like cytolytic effects from outgrowth of spores.

PubMed Central

Tayabali, A F; Seligy, V L

2000-01-01

Most contemporary bioinsecticides are derived from scaled-up cultures of Bacillus thuringiensis subspecies israelensis (Bti) and kurstaki (Btk), whose particulate fractions contain mostly B. thuringiensis spores (> 10(12)/L) and proteinaceous aggregates, including crystal-like parasporal inclusion bodies (PIB). Based on concerns over relatedness to B. cereus-group pathogens, we conducted extensive testing of B. thuringiensis (BT) products and their subfractions using seven human cell types. The Bti/Btk products generated nonspecific cytotoxicities involving loss in bioreduction, cell rounding, blebbing and detachment, degradation of immunodetectable proteins, and cytolysis. Their threshold dose (Dt approximately equal.5 times 10(-14)% BT product/target cell) equated to a single spore and a target cell half-life (tLD(50)) of approximately 16 hr. At Dts > 10(4), the tLD(50) rapidly shifted to < 4 hr; with antibiotic present, no component, including PIB-related [delta]-endotoxins, was cytolytic up to an equivalent of approximately 10(9 )Dt. The cytolytic agent(s) within the Bti/Btk-vegetative cell exoprotein (VCP) pool is an early spore outgrowth product identical to that of B. cereus and acting possibly by arresting protein synthesis. No cytolytic effects were seen with VCP from B. subtilis and Escherichia coli. These data, including recent epidemiologic work indicate that spore-containing BT products have an inherent capacity to lyse human cells in free and interactive forms and may also act as immune sensitizers. To critically impact at the whole body level, the exposure outcome would have to be an uncontrolled infection arising from intake of Btk/Bti spores. For humans, such a condition would be rare, arising possibly in equally rare exposure scenarios involving large doses of spores and individuals with weak or impaired microbe-clearance capacities and/or immune response systems. PMID:11049810

Effects of field orientation during 700-MHz radiofrequency irradiation of rats

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

Frei, M.R.; Jauchem, J.R.; Padilla, J.M.

1989-01-01

Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 700-MHz continuous-wave radiofrequency radiation (RFR) in both E and H orientations. Irradiation was conducted at whole-body average specific absorption rates (SARs) of 9.2 and 13.0 W/kg (E and H, respectively) that resulted in approximately equivalent colonic specific heating rates (SHRs). Exposures were performed to repeatedly increase colonic temperature by 1 deg C (38.5 to 39.5 deg C). Tympanic, tail, left and right subcutaneous (toward and away from RFR source), and colonic temperatures, arterial blood pressure, and respiratory rate were continuously recorded. In spite of equivalent colonic SHRs and the reduced E-orientation average SAR,more » the right subcutaneous, tympanic, and tail SARs, SHRs and absolute temperature increases were significantly greater in E than in H orientation. The cooling rate at all monitoring sites was also significantly greater in E than in H orientation. Heart rate and mean arterial blood pressure significantly increased during irradiation; however, changer between orientations were not different. Respiratory rate significantly increased during irradiation in H, but not in E orientation. These results indicate that during resonant frequency irradiation, differences occur in the pattern of heat deposition between E- and H-orientation exposure. When compared with previous investigations performed at supraresonant frequencies, the lower level of cardiovascular change in this study was probably related to the lower periphery-to-core thermal gradient.« less

Effects of field orientation during 700-MHz radiofrequency irradiation of rats

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

Frei, M.R.; Jauchem, J.R.; Padilla, J.M.

1989-01-01

Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 700-MHz continuous-wave radiofrequency radiation (RFR) in both E and H orientations. Irradiation was conducted at whole-body average specific absorption rates (SARs) of 9.2 and 13.0 W/kg (E and H, respectively) that resulted in approximately equivalent colonic specific heating rates (SHRs). Exposures were performed to repeatedly increase colonic temperature by 1 degree C (38.5 to 39.5 degrees C). Tympanic, tail, left and right subcutaneous (toward and away from RFR source), and colonic temperatures, arterial blood pressure, and respiratory rate were continuously recorded. In spite of equivalent colonic SHRs and the reduced E-orientation average SAR,more » the right subcutaneous, tympanic, and tail SARs, SHRs and absolute temperature increases were significantly greater in E than in H orientation. The cooling rate at all monitoring sites was also significantly greater in E than in H orientation. Heart rate and mean arterial blood pressure significantly increased during irradiation; however, changes between orientations were not different. Respiratory rate significantly increased during irradiation in H, but not in E orientation. These results indicate that during resonant frequency irradiation, differences occur in the pattern of heat deposition between E- and H-orientation exposure. When compared with previous investigations performed at supraresonant frequencies, the lower level of cardiovascular change in this study was probably related to the lower periphery-to-core thermal gradient.« less

Serum 25-hydroxyvitamin D level is associated with myopia in the Korea national health and nutrition examination survey.

PubMed

Kwon, Jin-Woo; Choi, Jin A; La, Tae Yoon

2016-11-01

The aim of this article was to assess the associations of serum 25-hydroxyvitamin D [25(OH)D] and daily sun exposure time with myopia in Korean adults.This study is based on the Korea National Health and Nutrition Examination Survey (KNHANES) of Korean adults in 2010-2012; multiple logistic regression analyses were performed to examine the associations of serum 25(OH)D levels and daily sun exposure time with myopia, defined as spherical equivalent ≤-0.5D, after adjustment for age, sex, household income, body mass index (BMI), exercise, intraocular pressure (IOP), and education level. Also, multiple linear regression analyses were performed to examine the relationship between serum 25(OH)D levels with spherical equivalent after adjustment for daily sun exposure time in addition to the confounding factors above.Between the nonmyopic and myopic groups, spherical equivalent, age, IOP, BMI, waist circumference, education level, household income, and area of residence differed significantly (all P < 0.05). Compared with subjects with daily sun exposure time <2 hour, subjects with sun exposure time ≥2 to <5 hour, and those with sun exposure time ≥5 hour had significantly less myopia (P < 0.001). In addition, compared with subjects were categorized into quartiles of serum 25(OH)D, the higher quartiles had gradually lower prevalences of myopia after adjustment for confounding factors (P < 0.001). In multiple linear regression analyses, spherical equivalent was significantly associated with serum 25(OH)D concentration after adjustment for confounding factors (P = 0.002).Low serum 25(OH)D levels and shorter daily sun exposure time may be independently associated with a high prevalence of myopia in Korean adults. These data suggest a direct role for vitamin D in the development of myopia.

Fate of inhaled azodicarbonamide in rats

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

Mewhinney, J.A.; Ayres, P.H.; Bechtold, W.E.

Azodicarbonamide (ADA) is widely used as a blowing agent in the manufacture of expanded foam plastics, as an aging and bleaching agent in flour, and as a bread dough conditioner. Human exposures have been reported during manufacture as well as during use. Groups of male F344/N rats were administered ADA by gavage, by intratracheal instillation, and by inhalation exposure to determine the disposition and modes of excretion of ADA and its metabolites. At 72 hr following gavage, 30% of the administered ADA was absorbed whereas following intratracheal instillation, absorption was 90%. Comparison between groups of rats exposed by inhalation tomore » ADA to achieve body burdens of 24 or 1230 micrograms showed no significant differences in modes or rates of excretion of (/sup 14/C)ADA equivalents. ADA was readily converted to biurea under physiological conditions and biurea was the only /sup 14/C-labeled compound present in excreta. (/sup 14/C)ADA equivalents were present in all examined tissues immediately after inhalation exposure, and clearance half-times on the order of 1 day were evident for all tissues investigated. Storage depots for (/sup 14/C)ADA equivalents were not observed. The rate of buildup of (/sup 14/C)ADA equivalents in blood was linearly related to the lung content as measured from rats withdrawn at selected times during a 6-hr inhalation exposure at an aerosol concentration of 25 micrograms ADA/liter. In a study extending 102 days after exposure, retention of (/sup 14/C)ADA equivalents in tissues was described by a two-component negative exponential function. The results from this study indicate that upon inhalation, ADA is rapidly converted to biurea and that biurea is then eliminated rapidly from all tissues with the majority of the elimination via the urine.« less

Simultaneous blood flow and blood oxygenation measurements using a combination of diffuse speckle contrast analysis and near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Seong, Myeongsu; Phillips, Zephaniah; Mai, Phuong Minh; Yeo, Chaebeom; Song, Cheol; Lee, Kijoon; Kim, Jae Gwan

2016-02-01

A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. Therefore, an optical density can be measured from two wavelengths for NIRS measurements and a speckle contrast can be calculated for DSCA measurements. In order to validate the system, a flow phantom test and an arm occlusion protocol for arterial and venous occlusion were performed. Shorter exposure times (<1 ms) show a higher drop (between 50% and 66%) and recovery of 1/KS2 values after occlusion (approximately 150%), but longer exposure time (3 ms) shows more consistent hemodynamic changes. For four subjects, the 1/KS2 values dropped to an average of 82.1±4.0% during the occlusion period and the average recovery of 1/KS2 values after occlusion was 109.1±0.8%. There was also an approximately equivalent amplitude change in oxyhemoglobin (OHb) and deoxyhemoglobin (RHb) during arterial occlusion (max RHb=0.0085±0.0024 mM/DPF, min OHb=-0.0057±0.0044 mM/DPF). The sensitivity of the system makes it a suitable modality to observe qualitative hemodynamic trends during induced physiological changes.

Intrinsic near-24-h pacemaker period determines limits of circadian entrainment to a weak synchronizer in humans

NASA Technical Reports Server (NTRS)

Wright, K. P. Jr; Hughes, R. J.; Kronauer, R. E.; Dijk, D. J.; Czeisler, C. A.

2001-01-01

Endogenous circadian clocks are robust regulators of physiology and behavior. Synchronization or entrainment of biological clocks to environmental time is adaptive and important for physiological homeostasis and for the proper timing of species-specific behaviors. We studied subjects in the laboratory for up to 55 days each to determine the ability to entrain the human clock to a weak circadian synchronizing stimulus [scheduled activity-rest cycle in very dim (approximately 1.5 lux in the angle of gaze) light-dark cycle] at three approximately 24-h periods: 23.5, 24.0, and 24.6 h. These studies allowed us to test two competing hypotheses as to whether the period of the human circadian pacemaker is near to or much longer than 24 h. We report here that imposition of a sleep-wake schedule with exposure to the equivalent of candle light during wakefulness and darkness during sleep is usually sufficient to maintain circadian entrainment to the 24-h day but not to a 23.5- or 24.6-h day. Our results demonstrate functionally that, in normally entrained sighted adults, the average intrinsic circadian period of the human biological clock is very close to 24 h. Either exposure to very dim light and/or the scheduled sleep-wake cycle itself can entrain this near-24-h intrinsic period of the human circadian pacemaker to the 24-h day.

10 CFR 835.203 - Combining internal and external equivalent doses.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Combining internal and external equivalent doses. 835.203 Section 835.203 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External Exposure § 835.203 Combining internal and external equivalent doses. (a) The total effective dose...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2010 CFR

2010-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2011 CFR

2011-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2014 CFR

2014-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2013 CFR

2013-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2012 CFR

2012-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

Code of Federal Regulations, 2012 CFR

2012-07-01

... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

Code of Federal Regulations, 2011 CFR

2011-07-01

... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

Code of Federal Regulations, 2013 CFR

2013-07-01

... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

Code of Federal Regulations, 2010 CFR

2010-07-01

... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

Alcohol Advertising on Boston's Massachusetts Bay Transportation Authority Transit System: An Assessment of Youths' and Adults' Exposure

PubMed Central

Nyborn, Justin A.; Wukitsch, Kimberly; Nhean, Siphannay

2009-01-01

Objectives. We investigated the frequency with which alcohol advertisements appeared on Massachusetts Bay Transportation Authority (MBTA) transit lines in Boston, MA, and we calculated adult and youths' exposure to the ads. Methods. We measured the nature and extent of alcohol advertisements on 4 Boston transit lines on 2 separate weekdays 1 month apart in June and July of 2008. We calculated weekday ad exposure for all passengers (all ages) and for Boston Public School student passengers (aged 11–18 years). Results. Alcohol ads were viewed an estimated 1 212 960 times across all Boston-area transit passengers during an average weekday, reaching the equivalent of 42.7% of that population. Alcohol ads were viewed an estimated 18 269 times by Boston Public School student transit passengers during an average weekday, reaching the equivalent of 54.1% of that population. Conclusions. Advertisers reached the equivalent of half of all Boston Public School transit passengers aged 11 to 18 years and the equivalent of nearly half of all transit passengers in the Boston area with an alcohol advertisement each day. Because of the high exposure of underage youths to alcohol advertisements, we recommend that the MBTA prohibit alcohol advertising on the Boston transit system. PMID:19890170

Photodegradation of clothianidin under simulated California rice field conditions.

PubMed

Mulligan, Rebecca A; Redman, Zachary C; Keener, Megan R; Ball, David B; Tjeerdema, Ronald S

2016-07-01

Photodegradation can be a major route of dissipation for pesticides applied to shallow rice field water, leading to diminished persistence and reducing the risk of offsite transport. The objective of this study was to characterize the aqueous-phase photodegradation of clothianidin under simulated California rice field conditions. Photodegradation of clothianidin was characterized in deionized, Sacramento River and rice field water samples. Pseudo-first-order rate constants and DT50 values in rice field water (mean k = 0.0158 min(-1) ; mean DT50 = 18.0 equivalent days) were significantly slower than in deionized water (k = 0.0167 min(-1) ; DT50 = 14.7 equivalent days) and river water (k = 0.0146 min(-1) ; DT50 = 16.6 equivalent days) samples. Quantum yield ϕc values demonstrate that approximately 1 and 0.5% of the light energy absorbed results in photochemical transformation in pure and field water respectively. Concentrations of the photodegradation product thiazolymethylurea in aqueous photolysis samples were determined using liquid chromatography-tandem mass spectrometry and accounted for ≤17% in deionized water and ≤8% in natural water. Photodegradation rates of clothianidin in flooded rice fields will be controlled by turbidity and light attenuation. Aqueous-phase photodegradation may reduce the risk of offsite transport of clothianidin from flooded rice fields (via drainage) and mitigate exposure to non-target organisms. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

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

Dong, Shang-Lung; Chu, Tieh-Chi; Lin, Yung-Chien

Purpose: Polymethylmethacrylate (PMMA) slab is one of the mostly used phantoms for studying breast dosimetry in mammography. The purpose of this study was to evaluate the equivalence between exposure factors acquired from PMMA slabs and patient cases of different age groups of Taiwanese women in mammography. Methods: This study included 3910 craniocaudal screen/film mammograms on Taiwanese women acquired on one mammographic unit. The tube loading, compressed breast thickness (CBT), compression force, tube voltage, and target/filter combination for each mammogram were collected for all patients. The glandularity and the equivalent thickness of PMMA were determined for each breast using the exposuremore » factors of the breast in combination with experimental measurements from breast-tissue-equivalent attenuation slabs. Equivalent thicknesses of PMMA to the breasts of Taiwanese women were then estimated. Results: The average {+-} standard deviation CBT and breast glandularity in this study were 4.2 {+-} 1.0 cm and 54% {+-} 23%, respectively. The average equivalent PMMA thickness was 4.0 {+-} 0.7 cm. PMMA slabs producing equivalent exposure factors as in the breasts of Taiwanese women were determined for the age groups 30-49 yr and 50-69 yr. For the 4-cm PMMA slab, the CBT and glandularity values of the equivalent breast were 4.1 cm and 65%, respectively, for the age group 30-49 yr and 4.4 cm and 44%, respectively, for the age group 50-69 yr. Conclusions: The average thickness of PMMA slabs producing the same exposure factors as observed in a large group of Taiwanese women is less than that reported for American women. The results from this study can provide useful information for determining a suitable thickness of PMMA for mammographic dose survey in Taiwan. The equivalence of PMMA slabs and the breasts of Taiwanese women is provided to allow average glandular dose assessment in clinical practice.« less

Calculation of reaction forces in the boiler supports using the method of equivalent stiffness of membrane wall.

PubMed

Sertić, Josip; Kozak, Dražan; Samardžić, Ivan

2014-01-01

The values of reaction forces in the boiler supports are the basis for the dimensioning of bearing steel structure of steam boiler. In this paper, the application of the method of equivalent stiffness of membrane wall is proposed for the calculation of reaction forces. The method of equalizing displacement, as the method of homogenization of membrane wall stiffness, was applied. On the example of "Milano" boiler, using the finite element method, the calculation of reactions in the supports for the real geometry discretized by the shell finite element was made. The second calculation was performed with the assumption of ideal stiffness of membrane walls and the third using the method of equivalent stiffness of membrane wall. In the third case, the membrane walls are approximated by the equivalent orthotropic plate. The approximation of membrane wall stiffness is achieved using the elasticity matrix of equivalent orthotropic plate at the level of finite element. The obtained results were compared, and the advantages of using the method of equivalent stiffness of membrane wall for the calculation of reactions in the boiler supports were emphasized.

In vitro assessment of equivalence of occupational health risk: welders.

PubMed Central

Stern, R M

1983-01-01

The possibility of using in vitro testing to determine the equivalence of risk for various occupational groups is discussed. In the absence of epidemiological evidence or relevant animal in vivo bioassays on which to determine the health effects of specific occupational exposures, it is proposed to use similarities in the in vitro response to substances with known (or strongly suspected) and unknown risk to demonstrate their risk equivalence. Identification and evaluation of a high risk "hot spot" due to exposure to Cr(VI) for stainless steel welders is discussed in terms of recent developments in collection, analysis and bioassay of welding fumes. PMID:6641655

Stormtime transport of ring current and radiation belt ions

NASA Technical Reports Server (NTRS)

Chen, Margaret W.; Schulz, Michael; Lyons, L. R.; Gorney, David J.

1993-01-01

This is an investigation of stormtime particle transport that leads to formation of the ring current. Our method is to trace the guiding-center motion of representative ions (having selected first adiabatic invariants mu) in response to model substorm-associated impulses in the convection electric field. We compare our simulation results qualitatively with existing analytically tractable idealizations of particle transport (direct convective access and radial diffusion) in order to assess the limits of validity of these approximations. For mu approximately less than 10 MeV/G (E approximately less than 10 keV at L equivalent to 3) the ion drift period on the final (ring-current) drift shell of interest (L equivalent to 3) exceeds the duration of the main phase of our model storm, and we find that the transport of ions to this drift shell is appropriately idealized as direct convective access, typically from open drift paths. Ion transport to a final closed drift path from an open (plasma-sheet) drift trajectory is possible for those portions of that drift path that lie outside the mean stormtime separatrix between closed and open drift trajectories, For mu approximately 10-25 MeV/G (110 keV approximately less than E approximately less than 280 keV at L equivalent to 3) the drift period at L equivalent to 3 is comparable to the postulated 3-hr duration of the storm, and the mode of transport is transitional between direct convective access and transport that resembles radial diffusion. (This particle population is transitional between the ring current and radiation belt). For mu approximately greater than 25 MeV/G (radiation-belt ions having E approximately greater than 280 keV at L equivalent to 3) the ion drift period is considerably shorter than the main phase of a typical storm, and ions gain access to the ring-current region essentially via radial diffusion. By computing the mean and mean-square cumulative changes in 1/L among (in this case) 12 representative ions equally spaced in drift time around the steady-state drift shell of interest (L equivalent to 3), we have estimated (from both our forward and our time-reversed simulations) the time-integrated radial-diffusion coefficients D(sup sim)(sub LL) for particles having selected values of mu approximately greater than 15 MeV/G. The results agree surprisingly well with the predictions (D(sup ql)(sub LL)) of quasilinear radial diffusion theory, despite the rather brief duration (approximately 3 hrs) of our model storm and despite the extreme variability (with frequency) of the spectral-density function that characterizes the applied electric field during our model storm. As expected, the values of D(sup sim)(sub LL) deduced (respectively) from our forward and time-reversed simulations agree even better with each other and with D(sup sim)(sub LL) when the impulse amplitudes which characterize the individual substorms of our model storm are systematically reduced.

Application of Matrix Projection Exposure Using a Liquid Crystal Display Panel to Fabricate Thick Resist Molds

NASA Astrophysics Data System (ADS)

Fukasawa, Hirotoshi; Horiuchi, Toshiyuki

2009-08-01

The patterning characteristics of matrix projection exposure using an analog liquid crystal display (LCD) panel in place of a reticle were investigated, in particular for oblique patterns. In addition, a new method for fabricating practical thick resist molds was developed. At first, an exposure system fabricated in past research was reconstructed. Changes in the illumination optics and the projection lens were the main improvements. Using fly's eye lenses, the illumination light intensity distribution was homogenized. The projection lens was changed from a common camera lens to a higher-grade telecentric lens. In addition, although the same metal halide lamp was used as an exposure light source, the central exposure wavelength was slightly shortened from 480 to 450 nm to obtain higher resist sensitivity while maintaining almost equivalent contrast between black and white. Circular and radial patterns with linewidths of approximately 6 µm were uniformly printed in all directions throughout the exposure field owing to these improvements. The patterns were smoothly printed without accompanying stepwise roughness caused by the cell matrix array. On the bases of these results, a new method of fabricating thick resist molds for electroplating was investigated. It is known that thick resist molds fabricated using the negative resist SU-8 (Micro Chem) are useful because very high aspect patterns are printable and the side walls are perpendicular to the substrate surfaces. However, the most suitable exposure wavelength of SU-8 is 365 nm, and SU-8 is insensitive to light of 450 nm wavelength, which is most appropriate for LCD matrix exposure. For this reason, a novel multilayer resist process was proposed, and micromolds of SU-8 of 50 µm thickness were successfully obtained. As a result, feasibility for fabricating complex resist molds including oblique patterns was demonstrated.

29 CFR 1915.89 - Control of hazardous energy (lockout/tags-plus).

Code of Federal Regulations, 2012 CFR

2012-07-01

... employee: (A) Sign a group tag (or a group tag equivalent), attach a personal identification device to a... group tag (or the group tag equivalent), remove the personal identification device, or perform a... safe exposure status of each authorized employee, and (b) signs a group tag (or a group tag equivalent...

29 CFR 1915.89 - Control of hazardous energy (lockout/tags-plus).

Code of Federal Regulations, 2013 CFR

2013-07-01

... employee: (A) Sign a group tag (or a group tag equivalent), attach a personal identification device to a... group tag (or the group tag equivalent), remove the personal identification device, or perform a... safe exposure status of each authorized employee, and (b) signs a group tag (or a group tag equivalent...

29 CFR 1915.89 - Control of hazardous energy (lockout/tags-plus).

Code of Federal Regulations, 2014 CFR

2014-07-01

... employee: (A) Sign a group tag (or a group tag equivalent), attach a personal identification device to a... group tag (or the group tag equivalent), remove the personal identification device, or perform a... safe exposure status of each authorized employee, and (b) signs a group tag (or a group tag equivalent...

42 CFR 81.4 - Definition of terms used in this part.

Code of Federal Regulations, 2011 CFR

2011-10-01

...]. (e) Equivalent dose means the absorbed dose in a tissue or organ multiplied by a radiation weighting... dose means the portion of the equivalent dose that is received from radiation sources outside of the... pattern and level of radiation exposure. (h) Internal dose means the portion of the equivalent dose that...

Climate specific thermomechanical fatigue of flat plate photovoltaic module solder joints

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

Bosco, Nick; Silverman, Timothy J.; Kurtz, Sarah

FEM simulations of PbSn solder fatigue damage are used to evaluate seven cities that represent a variety of climatic zones. It is shown that the rate of solder fatigue damage is not ranked with the cities' climate designations. For an accurate ranking, the mean maximum daily temperature, daily temperature change and a characteristic of clouding events are all required. A physics-based empirical equation is presented that accurately calculates solder fatigue damage according to these three factors. An FEM comparison of solder damage accumulated through service and thermal cycling demonstrates the number of cycles required for an equivalent exposure. For anmore » equivalent 25-year exposure, the number of thermal cycles (-40 degrees C to 85 degrees C) required ranged from roughly 100 to 630 for the cities examined. It is demonstrated that increasing the maximum cycle temperature may significantly reduce the number of thermal cycles required for an equivalent exposure.« less

Evaluation of Exposure From a Low Energy X-Ray Device Using Thermoluminescent Dosimeters

NASA Technical Reports Server (NTRS)

Edwards, David L.; Harris, William S., Jr.

1997-01-01

The exposure from an electron beam welding device was evaluated using thermoluminescent dosimeters (TLDs). The device generated low energy X-rays which the current dose equivalent conversion algorithm was not designed to evaluate making it necessary to obtain additional information relating to TLD operation at the photon energies encountered with the device. This was accomplished by performing irradiations at the National Institute of Standards and Technology (NIST) using low energy X-ray techniques. The resulting data was used to determine TLD badge response for low energy X-rays and to establish the relationship between TLD element response and the dose equivalent at specific depths in tissue for these photon energies. The new energy/dose equivalent calibration data was used to calculate the shallow and eye dose equivalent of badges exposed to the device.

Contributions of non-occupational activities to total noise exposure of construction workers.

PubMed

Neitzel, Richard; Seixas, Noah; Goldman, Bryan; Daniell, William

2004-07-01

This paper describes how exposures received during routine and episodic non-occupational activities contribute to total noise exposure in a group of occupationally exposed workers. Two-hundred and sixty-six construction apprentices enrolled in a longitudinal hearing loss study and completed questionnaires at 1 yr of follow-up to determine their episodic activities (e.g. concert attendance, power tool use, firearms exposure). Noise exposure levels for these episodic exposures were determined from the published literature. Routine activities were assessed using activity cards filled out over 530 subject-days, along with noise dosimetry measurements made over 124 subject-days of measurement. Equivalent Leq exposure levels were then calculated for specific activities. These activity-specific Leq values were combined into estimated individual annual Leq exposure levels for the 6760 nominal annual non-occupational hours in a year (LAeq6760h), which were then transformed into equivalent levels for a 2000 h exposure period (LA2000hn) for comparison with occupational noise exposure risk criteria. The mean non-occupational LAeq6760h exposure values for the cohort ranged from 56 to 87 dBA (equivalent LA2000hn 62-93 dBA). At the mid range of the routine and episodic activity exposure level distribution, the mean LAeq6760h was 73 dBA (LA2000hn 78 dBA). Nineteen percent of the LA2000hn non-occupational exposures exceeded 85 dBA, the generally recommended occupational limit for a 2000 h workyear, at the mid-range of exposure levels. Due to a lack of available data, firearms use could not be incorporated into the total noise exposure estimates. However, firearms users reported more exposure to other noisy non-occupational activities and had statistically significantly higher estimated exposure levels even without including their firearms exposure than did non-shooters. When compared with the high levels of occupational noise found in construction, non-occupational noise exposures generally present little additional exposure for most workers. However, they may contribute significantly to overall exposure in the subset of workers who frequently participate in selected noisy activities.

Reduction in radiation exposure to nursing personnel with the use of remote afterloading brachytherapy devices

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

Grigsby, P.W.; Perez, C.A.; Eichling, J.

The radiation exposure to nursing personnel from patients with brachytherapy implants on a large brachytherapy service were reviewed. Exposure to nurses, as determined by TLD monitors, indicates a 7-fold reduction in exposure after the implementation of the use of remote afterloading devices. Quarterly TLD monitor data for six quarters prior to the use of remote afterloading devices demonstrate an average projected annual dose equivalent to the nurses of 152 and 154 mrem (1.5 mSv). After the implementation of the remote afterloading devices, the quarterly TLD monitor data indicate an average dose equivalent per nurse of 23 and 19 mrem (0.2more » mSv). This is an 87% reduction in exposure to nurses with the use of these devices (p less than 0.01).« less

Exposure of miners to diesel exhaust particulates in underground nonmetal mines.

PubMed

Cohen, H J; Borak, J; Hall, T; Sirianni, G; Chemerynski, S

2002-01-01

A study was initiated to examine worker exposures in seven underground nonmetal mines and to examine the precision of the National Institute for Occupational Safety and Health (NIOSH) 5040 sampling and analytical method for diesel exhaust that has recently been adopted for compliance monitoring by the Mine Safety and Health Administration (MSHA). Approximately 1000 air samples using cyclones were taken on workers and in areas throughout the mines. Results indicated that worker exposures were consistently above the MSHA final limit of 160 micrograms/m3 (time-weighted average; TWA) for total carbon as determined by the NIOSH 5040 method and greater than the proposed American Conference of Governmental Industrial Hygienists TLV limit of 20 micrograms/m3 (TWA) for elemental carbon. A number of difficulties were documented when sampling for diesel exhaust using organic carbon: high and variable blank values from filters, a high variability (+/- 20%) from duplicate punches from the same sampling filter, a consistent positive interference (+26%) when open-faced monitors were sampled side-by-side with cyclones, poor correlation (r 2 = 0.38) to elemental carbon levels, and an interference from limestone that could not be adequately corrected by acid-washing of filters. The sampling and analytical precision (relative standard deviation) was approximately 11% for elemental carbon, 17% for organic carbon, and 11% for total carbon. An hypothesis is presented and supported with data that gaseous organic carbon constituents of diesel exhaust adsorb onto not only the submicron elemental carbon particles found in diesel exhaust, but also mining ore dusts. Such mining dusts are mostly nonrespirable and should not be considered equivalent to submicron diesel particulates in their potential for adverse pulmonary effects. It is recommended that size-selective sampling be employed, rather than open-faced monitoring, when using the NIOSH 5040 method.

Otologic consequences of blast exposure: a Finnish case study of a shopping mall bomb explosion.

PubMed

Mrena, Roderik; Pääkkönen, Rauno; Bäck, Leif; Pirvola, Ulla; Ylikoski, Jukka

2004-10-01

On 11 October, 2002, in the Myyrmanni shopping mall, Vantaa city, Finland, an explosion by a suicide bomber killed 7 people and injured at least 160,44 of whom had ear trauma. We investigated the acute and subacute otologic consequences of the explosion. Otologic examination of the 29 patients treated for ear trauma at the ENT clinic of the University Hospital of Helsinki was performed during the first month after the explosion, and a questionnaire was completed regarding subjective aural symptoms. Symptoms occurring directly after the explosion and for up to 1 month afterwards were assessed. Of the 29 patients, 66% had tinnitus as the initial symptom, 55% hearing loss, 41% pain in the ears and 28% sound distortion. Tinnitus and hearing loss in combination were experienced by 12 patients (41%). Eight patients who had been situated<10 m from the center of the explosion had a rupture of the tympanic membrane. This supported the initial evaluation by the authorities that the bomb had consisted of approximately 3 kg ammonium nitrate, equivalent to approximately 0.5 kg of trinitrotoluene. It was estimated that some kind of ear injury was likely for individuals situated<70 m from the center of the explosion. People often think that tinnitus and hearing impairment are naturally occurring phenomena after blast exposure, and if their symptoms resolve they do not seek medical advice. However, some of them may have substantial hearing impairment, particularly at high frequencies. Otologic consultation, or at least an audiometric screening test to exclude hearing impairment, should be performed regardless of symptoms, on the basis of exposure data only. Some symptoms, such as tinnitus and hearing loss, may be permanent consequences of a blast injury and their effect on quality of life may be substantial.

Total-dose radiation effects data for semiconductor devices. 1985 supplement. Volume 2, part A

NASA Technical Reports Server (NTRS)

Martin, K. E.; Gauthier, M. K.; Coss, J. R.; Dantas, A. R. V.; Price, W. E.

1986-01-01

Steady-state, total-dose radiation test data, are provided in graphic format for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. This volume provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done using the JPL or Boeing electron accelerator (Dynamitron) which provides a steady-state 2.5 MeV electron beam. However, some radiation exposures were made with a Cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose.

Effects of in ovo exposure to 2,3,7,8-TCDD on F1 generation adult chickens (Gallus gallus).

PubMed

Alonso, K R; Peden-Adams, M M; Liu, J Y; Charbonneau, C; Henshel, D; Dickerson, R L

1998-01-01

White Leghorn chickens (Gallus gallus) were used as surrogate species for the resident wild turkeys found on the Times Beach, Missouri, Superfund site. Parental chickens were injected with concentrations of 2,3,7,8-TCDD which modeled soil concentrations before (200 ppb) and after remediation (1ppb)[1]. Offspring were followed through development to assess alterations in reproductive maturity through the use of a four-way breeding study. F1 adult females exposed to a maternal dose of 8.6 ng/day began egg production approximately two weeks later than did F1 control adult females. By week eight, however, egg production between groups was equivalent. No differences were observed in eggshell gland estrogen or progesterone receptor levels.

Approximation methods for stochastic petri nets

NASA Technical Reports Server (NTRS)

Jungnitz, Hauke Joerg

1992-01-01

Stochastic Marked Graphs are a concurrent decision free formalism provided with a powerful synchronization mechanism generalizing conventional Fork Join Queueing Networks. In some particular cases the analysis of the throughput can be done analytically. Otherwise the analysis suffers from the classical state explosion problem. Embedded in the divide and conquer paradigm, approximation techniques are introduced for the analysis of stochastic marked graphs and Macroplace/Macrotransition-nets (MPMT-nets), a new subclass introduced herein. MPMT-nets are a subclass of Petri nets that allow limited choice, concurrency and sharing of resources. The modeling power of MPMT is much larger than that of marked graphs, e.g., MPMT-nets can model manufacturing flow lines with unreliable machines and dataflow graphs where choice and synchronization occur. The basic idea leads to the notion of a cut to split the original net system into two subnets. The cuts lead to two aggregated net systems where one of the subnets is reduced to a single transition. A further reduction leads to a basic skeleton. The generalization of the idea leads to multiple cuts, where single cuts can be applied recursively leading to a hierarchical decomposition. Based on the decomposition, a response time approximation technique for the performance analysis is introduced. Also, delay equivalence, which has previously been introduced in the context of marked graphs by Woodside et al., Marie's method and flow equivalent aggregation are applied to the aggregated net systems. The experimental results show that response time approximation converges quickly and shows reasonable accuracy in most cases. The convergence of Marie's method and flow equivalent aggregation are applied to the aggregated net systems. The experimental results show that response time approximation converges quickly and shows reasonable accuracy in most cases. The convergence of Marie's is slower, but the accuracy is generally better. Delay equivalence often fails to converge, while flow equivalent aggregation can lead to potentially bad results if a strong dependence of the mean completion time on the interarrival process exists.

Impact of Biodiesel Impurities on the Performance and Durability of DOC, DPF and SCR Technologies: Preprint

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

Williams, A.; McCormick, R.; Luecke, J.

2011-04-01

An accelerated durability test method determined the potential impact of biodiesel ash impurities, including engine testing with multiple diesel particulate filter substrate types, as well as diesel oxidation catalyst and selective catalyst reduction catalysts. The results showed no significant degradation in the thermo-mechanical properties of a DPF after exposure to 150,000-mile equivalent biodiesel ash and thermal aging. However, exposure to 435,000-mile equivalent aging resulted in a 69% decrease in thermal shock resistance. A decrease in DOC activity was seen after exposure to 150,000-mile equivalent aging, resulting in higher hydrocarbon slip and a reduction in NO2 formation. The SCR catalyst experiencedmore » a slight loss in activity after exposure to 435,000-mile equivalent aging. The SCR catalyst, placed downstream of the DPF and exposed to B20 exhaust suffered a 5% reduction in overall NOx conversion activity over the HDDT test cycle. It is estimated that the additional ash from 150,000 miles of biodiesel use would also result in a moderate increases in exhaust backpressure for a DPF. The results of this study suggest that long-term operation with B20 at the current specification limits for alkali and alkaline earth metal impurities will adversely impact the performance of DOC, DPF and SCR systems.« less

Analysis of fish bile with HPLC — fluorescence to determine environmental exposure to benzo(a)pyrene

USGS Publications Warehouse

Johnston, Eric P.; Baumann, Paul C.

1989-01-01

Brown bullhead from the Black River, Ohio, have a high incidence of liver neoplasia which is associated with elevated concentrations of polynuclear aromatic hydrocarbons (PAHs) in the sediment. We evaluated the use of biliary concentrations of benzo(a)pyrene [B(a)P] equivalents as a means for determining PAH exposure. Bile was collected from 16 brown bullheads and 8 common carp taken from each of two Lake Erie tributaries in Ohio, the industrialized Black River and the non-industrialized Old Woman Creek. Hatchery bullhead (n = 8) were used to determine base levels of PAHs. A high performance liquid chromatography (HPLC) — fluorescence technique was used to determine the concentration of B(a)P equivalents in the bile samples. The area of all peaks fluorescing at 380/430 nm was summed to give a single value for B(a)P equivalents in each sample. Concentrations of B(a)P equivalents generally reflected concentrations of PAH in sediment where fish were collected. Bile taken from Black River carp contained the highest concentration of B(a)P equivalents and was significantly different from all other groups. The value obtained for Black River bullhead was also high and was found to be significantly different from hatchery bullhead. B(a)P equivalents varied between carp and bullhead from the same habitat possibly because of differing food habits or metabolic pathways. However, our results indicate that relative levels of B(a)P equivalents in the bile of fish correspond well to B(a)P levels in sediment and may offer a means of determining environmental exposure of fish to the parent compound.

Impact of Biodiesel Impurities on the Performance and Durability of DOC, DPF and SCR Technologies

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

Williams, A.; McCormick, R.; Luecke, J.

2011-06-01

It is estimated that operating continuously on a B20 fuel containing the current allowable ASTM specification limits for metal impurities in biodiesel could result in a doubling of ash exposure relative to lube-oil derived ash. The purpose of this study was to determine if a fuel containing metals at the ASTM limits could cause adverse impacts on the performance and durability of diesel emission control systems. An accelerated durability test method was developed to determine the potential impact of these biodiesel impurities. The test program included engine testing with multiple DPF substrate types as well as DOC and SCR catalysts.more » The results showed no significant degradation in the thermo-mechanical properties of cordierite, aluminum titanate, or silicon carbide DPFs after exposure to 150,000 mile equivalent biodiesel ash and thermal aging. However, exposure of a cordierite DPF to 435,000 mile equivalent aging resulted in a 69% decrease in the thermal shock resistance parameter. It is estimated that the additional ash from 150,000 miles of biodiesel use would also result in a moderate increases in exhaust backpressure for a DPF. A decrease in DOC activity was seen after exposure to 150,000 mile equivalent aging, resulting in higher HC slip and a reduction in NO{sub 2} formation. The metal-zeolite SCR catalyst experienced a slight loss in activity after exposure to 435,000 mile equivalent aging. This catalyst, placed downstream of the DPF, showed a 5% reduction in overall NOx conversion activity over the HDDT test cycle.« less

XFEL diffraction: Developing processing methods to optimize data quality

DOE PAGES

Sauter, Nicholas K.

2015-01-29

Serial crystallography, using either femtosecond X-ray pulses from free-electron laser sources or short synchrotron-radiation exposures, has the potential to reveal metalloprotein structural details while minimizing damage processes. However, deriving a self-consistent set of Bragg intensities from numerous still-crystal exposures remains a difficult problem, with optimal protocols likely to be quite different from those well established for rotation photography. Here several data processing issues unique to serial crystallography are examined. It is found that the limiting resolution differs for each shot, an effect that is likely to be due to both the sample heterogeneity and pulse-to-pulse variation in experimental conditions. Shotsmore » with lower resolution limits produce lower-quality models for predicting Bragg spot positions during the integration step. Also, still shots by their nature record only partial measurements of the Bragg intensity. An approximate model that corrects to the full-spot equivalent (with the simplifying assumption that the X-rays are monochromatic) brings the distribution of intensities closer to that expected from an ideal crystal, and improves the sharpness of anomalous difference Fourier peaks indicating metal positions.« less

Evaluation of nonuniform field exposures with coupling factors.

PubMed

Sunohara, Tetsu; Hirata, Akimasa; Laakso, Ilkka; De Santis, Valerio; Onishi, Teruo

2015-10-21

In this study, the safety compliance for nonuniform field exposures is discussed using coupling factor concepts. The coupling factor, which is defined in the International Electrotechnical Commission 62311 standard, is extended to consider the effects of harmonics and also to apply to the specific absorption rate (for frequencies up to 30 MHz). The proposed compliance procedure is applied to and demonstrated for a prototype wireless power transfer (WPT) system with induction coupling operating at the fundamental frequency in 140 kHz band. First, measurements confirm that the perturbation of the external magnetic field strength and S11 parameter of a one-loop antenna by a human-equivalent phantom are sufficiently small, suggesting the applicability of the magneto-quasi-static approximation to frequencies up to 30 MHz. Then, the frequency characteristics of the coupling factor are derived for the WPT system. For the prototype system that is not optimized for commercial usage, the maximum allowable transmitting power is relaxed by a factor of 23 with the proposed procedure. The contribution of the harmonics decreased the allowable transmitting power by 39%, indicating their importance for safety compliance.

Calculation of Reaction Forces in the Boiler Supports Using the Method of Equivalent Stiffness of Membrane Wall

PubMed Central

Sertić, Josip; Kozak, Dražan; Samardžić, Ivan

2014-01-01

The values of reaction forces in the boiler supports are the basis for the dimensioning of bearing steel structure of steam boiler. In this paper, the application of the method of equivalent stiffness of membrane wall is proposed for the calculation of reaction forces. The method of equalizing displacement, as the method of homogenization of membrane wall stiffness, was applied. On the example of “Milano” boiler, using the finite element method, the calculation of reactions in the supports for the real geometry discretized by the shell finite element was made. The second calculation was performed with the assumption of ideal stiffness of membrane walls and the third using the method of equivalent stiffness of membrane wall. In the third case, the membrane walls are approximated by the equivalent orthotropic plate. The approximation of membrane wall stiffness is achieved using the elasticity matrix of equivalent orthotropic plate at the level of finite element. The obtained results were compared, and the advantages of using the method of equivalent stiffness of membrane wall for the calculation of reactions in the boiler supports were emphasized. PMID:24959612

High Altitude Radiations Relevant to the High Speed Civil Transport (HSCT)

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Goldhagan, P.; Maiden, D. L.; Tai, H.

2004-01-01

The Langley Research Center (LaRC) performed atmospheric radiation studies under the SST development program in which important ionizing radiation components were measured and extended by calculations to develop the existing atmospheric ionizing radiation (AIR) model. In that program the measured neutron spectrum was limited to less than 10 MeV by the available 1960-1970 instrumentation. Extension of the neutron spectrum to high energies was made using the LaRC PROPER-3C monte carlo code. It was found that the atmospheric neutrons contributed about half of the dose equivalent and approximately half of the neutron contribution was from high energy neutrons above 10 MeV. Furthermore, monte carlo calculations of solar particle events showed that potential exposures as large as 10-100 mSv/hr may occur on important high latitude routes but acceptable levels of exposure could be obtained if timely descent to subsonic altitudes could be made. The principal concern was for pregnant occupants onboard the aircraft. As a result of these studies the FAA Advisory Committee on the Radiobiological Aspects of the SST recommended: 1. Crew members will have to be informed of their exposure levels 2. Maximum exposures on any flight to be limited to 5 mSv 3. Airborne radiation detection devices for total exposure and exposure rates 4. Satellite monitoring system to provide SST aircraft real-time information on atmospheric radiation levels for exposure mitigation 5. A solar forecasting system to warn flight operations of an impending solar event for flight scheduling and alert status. These recommendations are a reasonable starting point to requirements for the HSCT with some modification reflecting new standards of protection as a result of changing risk coefficients.

Electromagnetic backscattering from a random distribution of lossy dielectric scatterers

NASA Technical Reports Server (NTRS)

Lang, R. H.

1980-01-01

Electromagnetic backscattering from a sparse distribution of discrete lossy dielectric scatterers occupying a region 5 was studied. The scatterers are assumed to have random position and orientation. Scattered fields are calculated by first finding the mean field and then by using it to define an equivalent medium within the volume 5. The scatterers are then viewed as being embedded in the equivalent medium; the distorted Born approximation is then used to find the scattered fields. This technique represents an improvement over the standard Born approximation since it takes into account the attenuation of the incident and scattered waves in the equivalent medium. The method is used to model a leaf canopy when the leaves are modeled by lossy dielectric discs.

The alarming problems of confounding equivalence using logistic regression models in the perspective of causal diagrams.

PubMed

Yu, Yuanyuan; Li, Hongkai; Sun, Xiaoru; Su, Ping; Wang, Tingting; Liu, Yi; Yuan, Zhongshang; Liu, Yanxun; Xue, Fuzhong

2017-12-28

Confounders can produce spurious associations between exposure and outcome in observational studies. For majority of epidemiologists, adjusting for confounders using logistic regression model is their habitual method, though it has some problems in accuracy and precision. It is, therefore, important to highlight the problems of logistic regression and search the alternative method. Four causal diagram models were defined to summarize confounding equivalence. Both theoretical proofs and simulation studies were performed to verify whether conditioning on different confounding equivalence sets had the same bias-reducing potential and then to select the optimum adjusting strategy, in which logistic regression model and inverse probability weighting based marginal structural model (IPW-based-MSM) were compared. The "do-calculus" was used to calculate the true causal effect of exposure on outcome, then the bias and standard error were used to evaluate the performances of different strategies. Adjusting for different sets of confounding equivalence, as judged by identical Markov boundaries, produced different bias-reducing potential in the logistic regression model. For the sets satisfied G-admissibility, adjusting for the set including all the confounders reduced the equivalent bias to the one containing the parent nodes of the outcome, while the bias after adjusting for the parent nodes of exposure was not equivalent to them. In addition, all causal effect estimations through logistic regression were biased, although the estimation after adjusting for the parent nodes of exposure was nearest to the true causal effect. However, conditioning on different confounding equivalence sets had the same bias-reducing potential under IPW-based-MSM. Compared with logistic regression, the IPW-based-MSM could obtain unbiased causal effect estimation when the adjusted confounders satisfied G-admissibility and the optimal strategy was to adjust for the parent nodes of outcome, which obtained the highest precision. All adjustment strategies through logistic regression were biased for causal effect estimation, while IPW-based-MSM could always obtain unbiased estimation when the adjusted set satisfied G-admissibility. Thus, IPW-based-MSM was recommended to adjust for confounders set.

On the equivalence of case-crossover and time series methods in environmental epidemiology.

PubMed

Lu, Yun; Zeger, Scott L

2007-04-01

The case-crossover design was introduced in epidemiology 15 years ago as a method for studying the effects of a risk factor on a health event using only cases. The idea is to compare a case's exposure immediately prior to or during the case-defining event with that same person's exposure at otherwise similar "reference" times. An alternative approach to the analysis of daily exposure and case-only data is time series analysis. Here, log-linear regression models express the expected total number of events on each day as a function of the exposure level and potential confounding variables. In time series analyses of air pollution, smooth functions of time and weather are the main confounders. Time series and case-crossover methods are often viewed as competing methods. In this paper, we show that case-crossover using conditional logistic regression is a special case of time series analysis when there is a common exposure such as in air pollution studies. This equivalence provides computational convenience for case-crossover analyses and a better understanding of time series models. Time series log-linear regression accounts for overdispersion of the Poisson variance, while case-crossover analyses typically do not. This equivalence also permits model checking for case-crossover data using standard log-linear model diagnostics.

Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit

NASA Astrophysics Data System (ADS)

El-Jaby, Samy; Richardson, Richard B.

2015-07-01

Occupational exposures from ionizing radiation are currently regulated for airline travel (<20 km) and for missions to low-Earth orbit (∼300-400 km). Aircrew typically receive between 1 and 6 mSv of occupational dose annually, while aboard the International Space Station, the area radiation dose equivalent measured over just 168 days was 106 mSv at solar minimum conditions. It is anticipated that space tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit.

Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit.

PubMed

El-Jaby, Samy; Richardson, Richard B

2015-07-01

Occupational exposures from ionizing radiation are currently regulated for airline travel (<20 km) and for missions to low-Earth orbit (∼300-400 km). Aircrew typically receive between 1 and 6 mSv of occupational dose annually, while aboard the International Space Station, the area radiation dose equivalent measured over just 168 days was 106 mSv at solar minimum conditions. It is anticipated that space tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Incorporation of additional radionuclides and the external exposure pathway into the BECAMP (Basic Environmental Compliance and Monitoring Program) radiological assessment model

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

Ng, Yook C.; Rodean, H.C.; Anspaugh, L.R.

The Nevada Applied Ecology Group (NAEG) Model of transport and dose for transuranic radionuclides was modified and expanded for the analysis of radionuclides other than pure alpha-emitters. Doses from internal and external exposures were estimated for the inventories and soil distributions of the individual radionuclides quantified in Areas 2 and 4 of the Nevada Test Site (NTS). We found that the dose equivalents via inhalation to liver, lungs, bone marrow, and bone surface from the plutonium isotopes and /sup 241/Am, those via ingestion to bone marrow and bone surfaces from /sup 90/Sr, and those via ingestion to all the targetmore » organs from /sup 137/Cs were the highest from internal exposures. The effective dose equivalents from /sup 137/Cs, /sup 152/Eu, and /sup 154/Eu were the highest from the external exposures. The /sup 60/Co, /sup 152/Eu, /sup 154/Eu, and /sup 155/Eu dose estimates for external exposures greatly exceeded those for internal exposures. The /sup 60/Co, /sup 90/Sr, and /sup 137/Cs dose equivalents from internal exposures were underestimated due to the adoption of some of the foodchain parameter values originally selected for /sup 239/Pu. Nonetheless, the ingestion pathway contributed significantly to the dose estimates for /sup 90/Sr and /sup 137/Cs, but contributed very much less than external exposures to the dose estimates for /sup 60/Co. Therefore, the use of more appropriate values would not alter the identification of important radionuclides, pathways, target organs, and exposure modes in this analysis. 19 refs., 13 figs., 12 tabs.« less

Comparison of experimental models for predicting laser-tissue interaction from 3.8-micron lasers

NASA Astrophysics Data System (ADS)

Williams, Piper C. M.; Winston, Golda C. H.; Randolph, Don Q.; Neal, Thomas A.; Eurell, Thomas E.; Johnson, Thomas E.

2004-07-01

The purpose of this study was to evaluate the laser-tissue interactions of engineered human skin and in-vivo pig skin following exposure to a single 3.8 micron laser light pulse. The goal of the study was to determine if these tissues shared common histologic features following laser exposure that might prove useful in developing in-vitro and in-vivo experimental models to predict the bioeffects of human laser exposure. The minimum exposure required to produce gross morphologic changes following a four microsecond, pulsed skin exposure for both models was determined. Histology was used to compare the cellular responses of the experimental models following laser exposure. Eighteen engineered skin equivalents (in-vitro model), were exposed to 3.8 micron laser light and the tissue responses compared to equivalent exposures made on five Yorkshire pigs (in-vivo model). Representative biopsies of pig skin were taken for histologic evaluation from various body locations immediately, one hour, and 24 hours following exposure. The pattern of epithelial changes seen following in-vitro laser exposure of the engineered human skin and in-vivo exposure of pig skin indicated a common histologic response for this particular combination of laser parameters.

Coal fly ash and lime addition enhances the rate and efficiency of decomposition of food waste during composting.

PubMed

Wong, Jonathan W-C; Fung, Shun On; Selvam, Ammaiyappan

2009-07-01

To evaluate the use of coal fly ash (CFA) on the decomposition efficiency of food waste, synthetic food waste was mixed with lime at 1.5% and 3% (equivalent to 0.94% and 1.88% CaCO(3), respectively), CFA at 5%, 10% and 15% with lime so as to achieve CaCO(3) equivalent of 1.88% and composted for 42 days in a thermophilic 20 l composter with two replicates each. Alkaline materials at 1.88% CaCO(3) equivalent successfully buffered the pH during the composting and enhanced the decomposition efficiency. When these buffering was achieved with CFA+lime, the composting period could be shortened to approximately 28 days compared with approximately 42 days in 3% lime. Organic decomposition in terms of CO(2) loss, carbon turnover and nitrogen transformation were significantly higher for treatments with 1.88% CaCO(3) equivalent. Nutrient transformations and compost maturity parameters indicated that addition of CFA (5-10%) with lime at 1.88% CaCO(3) equivalent enhances the decomposition efficiency and shortens the composting period by 35%.

Space Environmentally Stable Polyimides and Copolyimides

NASA Technical Reports Server (NTRS)

Watson, Kent A.; Connell, John W.

2000-01-01

Polyimides with a unique combination of properties including low color in thin films, atomic oxygen (AO), ultra-violet (UV) radiation resistance, solubility in organic solvents in the imide form, high glass transition (T(sub g)) temperatures and high thermal stability have been prepared and characterized. The polymers were prepared by reacting a novel aromatic diamine with aromatic dianhydrides in a polar aprotic solvent. The solubility of the polymers in the imide form as well as the color density of thin films were dependent upon the chemical structure of the dianhydride. Several thin films (25-50 mm thick) prepared by solution casting of amide acid or imide solutions exhibited very low color and high optical transparency (approximately 90%) as determined by UV/visible spectroscopy. The polymers exhibited T(sub g)s >200 C depending upon the structure of the dianhydride and temperatures of 5% weight loss approximately 500C in air as determined by dynamic thermogravimetric analysis. Thin films coated with silver/inconel were exposed to a high fluence of AO and 1000 equivalent solar hours of UV radiation. The effects of these exposures on optical properties were minor. These space environmentally durable polymers are potentially useful in a variety of applications on spacecraft such as thin film membranes on antennas, second-surface mirrors, thermal/optical coatings and multi-layer thermal insulation (MLI) blanket materials. The chemistry, physical and mechanical properties of the polymers as well as their responses to AO and UV exposure will be discussed.

The leaded apron revisited: does it reduce gonadal radiation dose in dental radiology?

PubMed

Wood, R E; Harris, A M; van der Merwe, E J; Nortjé, C J

1991-05-01

A tissue-equivalent anthropomorphic human phantom was used with a lithium fluoride thermoluminescent dosimetry system to evaluate the radiation absorbed dose to the ovarian and testicular region during dental radiologic procedures. Measurements were made with and without personal lead shielding devices consisting of thyroid collar and apron of 0.25 mm lead thickness equivalence. The radiation absorbed dose with or without lead shielding did not differ significantly from control dosimeters in vertex occlusal and periapical views (p greater than 0.05). Personal lead shielding devices did reduce gonadal dose in the case of accidental exposure (p less than 0.05). A leaded apron of 0.25 mm lead thickness equivalent was permeable to radiation in direct exposure testing.

The uptake, distribution, metabolism, and excretion of methyl tertiary-butyl ether inhaled alone and in combination with gasoline vapor.

PubMed

Benson, Janet M; Tibbetts, Brad M; Barr, Edward B

2003-06-13

The purpose of these studies was to evaluate the tissue uptake, distribution, metabolism, and excretion of methyl tertiary-butyl ether (MTBE) in rats and to determine the effects of coinhalation of the volatile fraction of unleaded gasoline on these parameters. Male F344 rats were exposed nose-only once for 4 h to 4, 40, or 400 ppm 14C-MTBE and to 20 and 200 ppm of the light fraction of unleaded gasoline (LFG) containing 4 and 40 ppm 14C-MTBE, respectively. To evaluate the effects of repeated inhalation of LFG on the fate of inhaled MTBE, rats were exposed for 7 consecutive days to 20 and 200 ppm LFG followed on d 8 by exposure to LFG containing 14C-MTBE. Three subgroups of rats were included for evaluation of respiratory parameters, rates and routes of excretion, and tissue distribution and elimination. MTBE and its chief metabolite, tertiary-butyl alcohol, were quantitated in blood and kidney (immediately after exposure), and the major urinary metabolites, 2-hydroxyisobutyric acid and 2-methyl-1,2- propanediol, were identified and quantified in urine. Inhalation of MTBE alone or as a component of LFG had no concentration-dependent effect on respiratory minute volume. The initial body burdens (IBBs) of MTBE equivalents achieved after 4 h of exposure to MTBE did not increase linearly with exposure concentration. MTBE equivalents rapidly distributed to all tissues examined, with the largest percentages distributed to liver. Between 40 and 400 ppm, there was a significant reduction in percentage of the IBB present in the major organs examined, both immediately and 72 h after exposure. At 400 ppm, the elimination rates of MTBE equivalents from tissues changed significantly. Furthermore, at 400 ppm there was a significant decrease in the elimination half-time of volatile organic compounds (VOCs) in breath and a significant increase in the percentage of the IBB of MTBE equivalents eliminated as VOCs in breath. LFG coexposure significantly decreased the percentage of the MTBE equivalent IBBs in tissues and increased rates of elimination of MTBE equivalents. The study results indicate that the uptake and fate of inhaled MTBE are altered upon increasing exposure levels from 4 to 400 ppm, suggesting that toxic effects observed previously upon repeated inhalation of concentrations of 400 ppm or greater may not necessarily be linearly extrapolated to effects that might occur at lower concentrations. Furthermore, coexposure to LFG, whether acute or repeated, decreases tissue burdens of MTBE equivalents and enhances the elimination rate of MTBE and its metabolites, thereby potentially reducing the toxic effects of the MTBE compared to when it is inhaled alone.

Determination of shielding requirements for mammography.

PubMed

Okunade, Akintunde Akangbe; Ademoroti, Olalekan Albert

2004-05-01

Shielding requirements for mammography when considerations are to be given to attenuation by compression paddle, breast tissue, grid and image receptor (intervening materials) has been investigated. By matching of the attenuation and hardening properties, comparisons are made between shielding afforded by breast tissue materials (water, Lucite and 50%-50% adipose-glandular tissue) and some materials considered for shielding diagnostic x-ray beams, namely lead, steel and gypsum wallboard. Results show that significant differences exist between the thickness required to produce equal attenuation and that required to produce equal hardening of a given incident beam. While attenuation equivalent thickness produces equal exposure, it does not produce equal hardening. For shielding purposes, equivalence in exposure reduction without equivalence in penetrating power of an emerging beam does not amount to equivalence in shielding affordable by two different materials. Presented are models and results of sample calculations of additional shielding requirements apart from that provided by intervening materials. The shielding requirements for the integrated beam emerging from intervening materials are different from those for the integrated beam emerging from materials (lead/steel/gypsum wallboard) with attenuation equivalent thicknesses of these intervening materials.

Occupational safety considerations with hydrazine fuels

NASA Technical Reports Server (NTRS)

Clewell, H. J.; Haddad, T. S.; George, M. E.; Mcdougal, J. N.; Andersen, M. E.

1992-01-01

A simple pharmacokinetic model and a specially designed dermal vapor exposure chamber which provides respiratory protection were used to determine the rate of penetration of hydrazine and 1,1-dimethylhydrazine (UDMH) vapor through the skin of rats. Parameters for the pharmacokinetic model were determined from intravenous and inhalation exposure data. The model was then used to estimate the skin permeation coefficient for hydrazine or UDMH vapor from the dermal-vapor exposure data. This analysis indicates that UDMH vapor has a relatively high permeability through skin (0.7 cm/hr), a value somewhat higher than was obtained for hydrazine by the same procedure (0.09 cm/hr). Based on these skin permeability results, a skin-only vapor exposure limit giving protection equivalent to the inhalation Threshold Limit Value (TLV) could be calculated. The current TLV's for UDMH and hydrazine are 0.5 and 0.1 ppm, respectively. The corresponding skin-only TLV equivalents, for personnel wearing respiratory protection, are 32 ppm for UDMH and 48 ppm for hydrazine. Should the proposed lowering to the TLV's for these compounds to 0.01 ppm be adopted, the equivalent skin-only TLV's would become 0.64 ppm for UDMH and 4.8 for hydrazine.

Cancer Risk Assessment of Polycyclic Aromatic Hydrocarbons in the Soils and Sediments of India: A Meta-Analysis.

PubMed

Tarafdar, Abhrajyoti; Sinha, Alok

2017-10-01

A carcinogenic risk assessment of polycyclic aromatic hydrocarbons in soils and sediments was conducted using the probabilistic approach from a national perspective. Published monitoring data of polycyclic aromatic hydrocarbons present in soils and sediments at different study points across India were collected and converted to their corresponding BaP equivalent concentrations. These BaP equivalent concentrations were used to evaluate comprehensive cancer risk for two different age groups. Monte Carlo simulation and sensitivity analysis were applied to quantify uncertainties of risk estimation. The analysis denotes 90% cancer risk value of 1.770E-5 for children and 3.156E-5 for adults at heavily polluted site soils. Overall carcinogenic risks of polycyclic aromatic hydrocarbons in soils of India were mostly in acceptance limits. However, the food ingestion exposure route for sediments leads them to a highly risked zone. The 90% risk values from sediments are 7.863E-05 for children and 3.999E-04 for adults. Sensitivity analysis reveals exposure duration and relative skin adherence factor for soil as the most influential parameter of the assessment, followed by BaP equivalent concentration of polycyclic aromatic hydrocarbons. For sediments, biota to sediment accumulation factor of fish in terms of BaP is most sensitive on the total outcome, followed by BaP equivalent and exposure duration. Individual exposure route analysis showed dermal contact for soils and food ingestion for sediments as the main exposure pathway. Some specific locations such as surrounding areas of Bhavnagar, Raniganj, Sunderban, Raipur, and Delhi demand potential strategies of carcinogenic risk management and reduction. The current study is probably the first attempt to provide information on the carcinogenic risk of polycyclic aromatic hydrocarbons in soil and sediments across India.

Cancer Risk Assessment of Polycyclic Aromatic Hydrocarbons in the Soils and Sediments of India: A Meta-Analysis

NASA Astrophysics Data System (ADS)

Tarafdar, Abhrajyoti; Sinha, Alok

2017-10-01

A carcinogenic risk assessment of polycyclic aromatic hydrocarbons in soils and sediments was conducted using the probabilistic approach from a national perspective. Published monitoring data of polycyclic aromatic hydrocarbons present in soils and sediments at different study points across India were collected and converted to their corresponding BaP equivalent concentrations. These BaP equivalent concentrations were used to evaluate comprehensive cancer risk for two different age groups. Monte Carlo simulation and sensitivity analysis were applied to quantify uncertainties of risk estimation. The analysis denotes 90% cancer risk value of 1.770E-5 for children and 3.156E-5 for adults at heavily polluted site soils. Overall carcinogenic risks of polycyclic aromatic hydrocarbons in soils of India were mostly in acceptance limits. However, the food ingestion exposure route for sediments leads them to a highly risked zone. The 90% risk values from sediments are 7.863E-05 for children and 3.999E-04 for adults. Sensitivity analysis reveals exposure duration and relative skin adherence factor for soil as the most influential parameter of the assessment, followed by BaP equivalent concentration of polycyclic aromatic hydrocarbons. For sediments, biota to sediment accumulation factor of fish in terms of BaP is most sensitive on the total outcome, followed by BaP equivalent and exposure duration. Individual exposure route analysis showed dermal contact for soils and food ingestion for sediments as the main exposure pathway. Some specific locations such as surrounding areas of Bhavnagar, Raniganj, Sunderban, Raipur, and Delhi demand potential strategies of carcinogenic risk management and reduction. The current study is probably the first attempt to provide information on the carcinogenic risk of polycyclic aromatic hydrocarbons in soil and sediments across India.

29 CFR 1926.60 - Methylenedianiline.

Code of Federal Regulations, 2011 CFR

2011-07-01

... term exposure limit as determined by any 15-minute sample period. (c) Permissible exposure limits. The... required in paragraphs (i) and (j) of this section until the emergency is abated. (iii) The plan shall...) Where the employer can document that exposure levels are equivalent for similar operations in different...

29 CFR 1926.60 - Methylenedianiline.

Code of Federal Regulations, 2010 CFR

2010-07-01

... term exposure limit as determined by any 15-minute sample period. (c) Permissible exposure limits. The... required in paragraphs (i) and (j) of this section until the emergency is abated. (iii) The plan shall...) Where the employer can document that exposure levels are equivalent for similar operations in different...

Interferometric observations of an artificial satellite.

PubMed

Preston, R A; Ergas, R; Hinteregger, H F; Knight, C A; Robertson, D S; Shapiro, I I; Whitney, A R; Rogers, A E; Clark, T A

1972-10-27

Very-long-baseline interferometric observations of radio signals from the TACSAT synchronous satellite, even though extending over only 7 hours, have enabled an excellent orbit to be deduced. Precision in differenced delay and delay-rate measurements reached 0.15 nanosecond ( approximately 5 centimeters in equivalent differenced distance) and 0.05 picosecond per second ( approximately 0.002 centimeter per second in equivalent differenced velocity), respectively. The results from this initial three-station experiment demonstrate the feasibility of using the method for accurate satellite tracking and for geodesy. Comparisons are made with other techniques.

The Effect of Different Water Temperatures on Retention Loss and Material Degradation of Locator Attachments.

PubMed

Chiu, Lillian Pui Yuk; Vitale, Nicola Di; Petridis, Haralampos; McDonald, Ailbhe

2017-08-01

To examine the changes in Locator attachments after exposure to different water temperatures and cyclic loading. Four groups of pink Locator attachments (3.0 lb. light retention replacement patrix attachments; 10 per group) were soaked for the equivalent of 5 years of use in distilled water at the following temperatures: 20°C, 37°C, 60°C. One group was kept dry to test the effect of water. A universal testing machine was used to measure the retention force of each treated attachment during 5500 insertion and removal cycles, simulating approximately 5 years of use. The results were compared using Kruskal-Wallis one-way ANOVA by ranks. Surface changes of tested attachments were examined using scanning electron microscopy (SEM). The exposure to 60°C water significantly increased the percentage of retention loss in Locator attachments (p < 0.05) compared to the 20°C water group and significantly reduced the final retention force compared to the other groups (p < 0.05). SEM examinations revealed severe cracking and material degradation in Locator attachments after exposure to 60°C water and cyclic loading, which were not evident in other groups. Cracking was observed after exposure to 60˚C water before cyclic loading. Exposure to 60°C water, potentially similar to denture cleansing procedures, could cause cracking in Locator attachments. Cracking is associated with hydrolytic degradation of nylon at 60°C. The change in structure could result in a significant loss of retention. © 2016 by the American College of Prosthodontists.

Fiber Composite Sandwich Thermostructural Behavior: Computational Simulation

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Aiello, R. A.; Murthy, P. L. N.

1986-01-01

Several computational levels of progressive sophistication/simplification are described to computationally simulate composite sandwich hygral, thermal, and structural behavior. The computational levels of sophistication include: (1) three-dimensional detailed finite element modeling of the honeycomb, the adhesive and the composite faces; (2) three-dimensional finite element modeling of the honeycomb assumed to be an equivalent continuous, homogeneous medium, the adhesive and the composite faces; (3) laminate theory simulation where the honeycomb (metal or composite) is assumed to consist of plies with equivalent properties; and (4) derivations of approximate, simplified equations for thermal and mechanical properties by simulating the honeycomb as an equivalent homogeneous medium. The approximate equations are combined with composite hygrothermomechanical and laminate theories to provide a simple and effective computational procedure for simulating the thermomechanical/thermostructural behavior of fiber composite sandwich structures.

Clinical Evaluation of Protective Garments with Respect to Garment Characteristics and Manufacturer Label Information.

PubMed

Lichliter, Andrew; Weir, Victor; Heithaus, Robert Evans; Gipson, Sean; Syed, Almas; West, James; Rees, Chet

2017-01-01

To test operator exposures inside radiation protection garments in a simulated clinical setup, examining trends related to multiple characteristics. Sixteen garment models containing lead or nonlead materials and a suspended device (Zero-Gravity) were tested for operator exposure from X rays scattered from an acrylic patient phantom. Weight and surface area were determined. The operator phantom was a wooden frame containing a dosimeter in its cavity. Garments were draped over the frame, and the setup was placed in a typical working position. There was substantial variability in exposures for all garments, ranging from 0.52 to 13.8 µSv/h (mean, 5.39 µSv/h ± 3.82), with a 12-fold difference for garments labeled 0.5 mm Pb equivalent. Most of the especially poor protectors were nonlead, even when not lightweight. Nonlead models were not more protective per weight overall. For closed-back garments labeled 0.5 mm Pb equivalent, mean exposures were lower for lead than for nonlead materials (mean, 1.48 µSv/h ± 0.434 vs 6.26 µSv/h ± 5.13, respectively). Density per exposure -1 was lower for lead than nonlead materials in the 0.5-mm Pb equivalent group, counter to advertised claims. Open-back configurations were lighter than closed (3.3 kg vs 6.0 kg, respectively), with similar mean exposures (5.30 µSv/h vs 5.39 µSv/h, respectively). The lowest exposure was 0.52 µSv/h (9.8% of the mean of all garments) for the suspended device. Operator exposure in a realistic interventional setup is highly variable for similarly labeled protective garments, highlighting the necessity of internal validation when considering nonlead and lightweight models. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

Estimation of chloroform inhalation dose by other routes based on the relationship of area under the blood concentration-time curve (AUC)-inhalation dose to chloroform distribution in the blood of rats.

PubMed

Take, Makoto; Takeuchi, Tetsuya; Haresaku, Mitsuru; Matsumoto, Michiharu; Nagano, Kasuke; Yamamoto, Seigo; Takamura-Enya, Takeji; Fukushima, Shoji

2014-01-01

The present study investigated the time-course changes of concentration of chloroform (CHCl3) in the blood during and after exposure of male rats to CHCl3 by inhalation. Increasing the dose of CHCl3 in the inhalation exposed groups caused a commensurate increase in the concentration of CHCl3 in the blood and the area under the blood concentration-time curve (AUC). There was good correlation (r = 0.988) between the inhalation dose and the AUC/kg body weight. Based on the AUC/kg body weight-inhalation dose curve and the AUC/kg body weight after oral administration, inhalation equivalent doses of orally administered CHCl3 were calculated. Calculation of inhalation equivalent doses allows the body burden due to CHCl3 by inhalation exposure and oral exposure to be directly compared. This type of comparison facilitates risk assessment in humans exposed to CHCl3 by different routes. Our results indicate that when calculating inhalation equivalent doses of CHCl3, it is critical to include the AUC from the exposure period in addition to the AUC after the end of the exposure period. Thus, studies which measure the concentration of volatile organic compounds in the blood during the inhalation exposure period are crucial. The data reported here makes an important contribution to the physiologically based pharmacokinetic (PBPK) database of CHCl3 in rodents.

Assessment of the magnetic field exposure due to the battery current of digital mobile phones.

PubMed

Jokela, Kari; Puranen, Lauri; Sihvonen, Ari-Pekka

2004-01-01

Hand-held digital mobile phones generate pulsed magnetic fields associated with the battery current. The peak value and the waveform of the battery current were measured for seven different models of digital mobile phones, and the results were applied to compute approximately the magnetic flux density and induced currents in the phone-user's head. A simple circular loop model was used for the magnetic field source and a homogeneous sphere consisting of average brain tissue equivalent material simulated the head. The broadband magnetic flux density and the maximal induced current density were compared with the guidelines of ICNIRP using two various approaches. In the first approach the relative exposure was determined separately at each frequency and the exposure ratios were summed to obtain the total exposure (multiple-frequency rule). In the second approach the waveform was weighted in the time domain with a simple low-pass RC filter and the peak value was divided by a peak limit, both derived from the guidelines (weighted peak approach). With the maximum transmitting power (2 W) the measured peak current varied from 1 to 2.7 A. The ICNIRP exposure ratio based on the current density varied from 0.04 to 0.14 for the weighted peak approach and from 0.08 to 0.27 for the multiple-frequency rule. The latter values are considerably greater than the corresponding exposure ratios 0.005 (min) to 0.013 (max) obtained by applying the evaluation based on frequency components presented by the new IEEE standard. Hence, the exposure does not seem to exceed the guidelines. The computed peak magnetic flux density exceeded substantially the derived peak reference level of ICNIRP, but it should be noted that in a near-field exposure the external field strengths are not valid indicators of exposure. Currently, no biological data exist to give a reason for concern about the health effects of magnetic field pulses from mobile phones.

Spatial traffic noise pollution assessment - A case study.

PubMed

Monazzam, Mohammad Reza; Karimi, Elham; Abbaspour, Majid; Nassiri, Parvin; Taghavi, Lobat

2015-01-01

Spatial assessment of traffic noise pollution intensity will provide urban planners with approximate estimation of citizens exposure to impermissible sound levels. They could identify critical noise pollution areas wherein noise barriers should be embedded. The present study aims at using the Geographic Information System (GIS) to assess spatial changes in traffic noise pollution in Tehran, the capital of Iran, and the largest city in the Middle East. For this purpose, while measuring equivalent sound levels at different time periods of a day and different days of a week in District 14 of Tehran, wherein there are highways and busy streets, the geographic coordination of the measurement points was recorded at the stations. The obtained results indicated that the equivalent sound level did not show a statistically significant difference between weekdays, and morning, afternoon and evening hours as well as time intervals of 10 min, 15 min and 30 min. Then, 91 stations were selected in the target area and equivalent sound level was measured for each station on 3 occasions of the morning (7:00-9:00 a.m.), afternoon (12.00-3:00 p.m.) and evening (5:00-8:00 p.m.) on Saturdays to Wednesdays. As the results suggest, the maximum equivalent sound level (Leq) was reported from Basij Highway, which is a very important connecting thoroughfare in the district, and was equal to 84.2 dB(A), while the minimum equivalent sound level (Leq), measured in the Fajr Hospital, was equal to 59.9 dB(A). The average equivalent sound level was higher than the national standard limit at all stations. The use of sound walls in Highways Basij and Mahallati as well as widening the Streets 17th Shahrivar, Pirouzi and Khavaran, benchmarked on a map, were recommended as the most effective mitigation measures. Additionally, the research findings confirm the outstanding applicability of the Geographic Information System in handling noise pollution data towards depicting noise pollution intensity caused by traffic. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Antipsychotic dose equivalents and dose-years: a standardized method for comparing exposure to different drugs.

PubMed

Andreasen, Nancy C; Pressler, Marcus; Nopoulos, Peg; Miller, Del; Ho, Beng-Choon

2010-02-01

A standardized quantitative method for comparing dosages of different drugs is a useful tool for designing clinical trials and for examining the effects of long-term medication side effects such as tardive dyskinesia. Such a method requires establishing dose equivalents. An expert consensus group has published charts of equivalent doses for various antipsychotic medications for first- and second-generation medications. These charts were used in this study. Regression was used to compare each drug in the experts' charts to chlorpromazine and haloperidol and to create formulas for each relationship. The formulas were solved for chlorpromazine 100 mg and haloperidol 2 mg to derive new chlorpromazine and haloperidol equivalents. The formulas were incorporated into our definition of dose-years such that 100 mg/day of chlorpromazine equivalent or 2 mg/day of haloperidol equivalent taken for 1 year is equal to one dose-year. All comparisons to chlorpromazine and haloperidol were highly linear with R(2) values greater than .9. A power transformation further improved linearity. By deriving a unique formula that converts doses to chlorpromazine or haloperidol equivalents, we can compare otherwise dissimilar drugs. These equivalents can be multiplied by the time an individual has been on a given dose to derive a cumulative value measured in dose-years in the form of (chlorpromazine equivalent in mg) x (time on dose measured in years). After each dose has been converted to dose-years, the results can be summed to provide a cumulative quantitative measure of lifetime exposure. Copyright 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Characterization and validation of the thorax phantom Lungman for dose assessment in chest radiography optimization studies.

PubMed

Rodríguez Pérez, Sunay; Marshall, Nicholas William; Struelens, Lara; Bosmans, Hilde

2018-01-01

This work concerns the validation of the Kyoto-Kagaku thorax anthropomorphic phantom Lungman for use in chest radiography optimization. The equivalence in terms of polymethyl methacrylate (PMMA) was established for the lung and mediastinum regions of the phantom. Patient chest examination data acquired under automatic exposure control were collated over a 2-year period for a standard x-ray room. Parameters surveyed included exposure index, air kerma area product, and exposure time, which were compared with Lungman values. Finally, a voxel model was developed by segmenting computed tomography images of the phantom and implemented in PENELOPE/penEasy Monte Carlo code to compare phantom tissue-equivalent materials with materials from ICRP Publication 89 in terms of organ dose. PMMA equivalence varied depending on tube voltage, from 9.5 to 10.0 cm and from 13.5 to 13.7 cm, for the lungs and mediastinum regions, respectively. For the survey, close agreement was found between the phantom and the patients' median values (deviations lay between 8% and 14%). Differences in lung doses, an important organ for optimization in chest radiography, were below 13% when comparing the use of phantom tissue-equivalent materials versus ICRP materials. The study confirms the value of the Lungman for chest optimization studies.

Development and characterization of a dual-energy subtraction imaging system for chest radiography based on CsI:Tl amorphous silicon flat-panel technology

NASA Astrophysics Data System (ADS)

Sabol, John M.; Avinash, Gopal B.; Nicolas, Francois; Claus, Bernhard E. H.; Zhao, Jianguo; Dobbins, James T., III

2001-06-01

Dual-energy subtraction imaging increases the sensitivity and specificity of pulmonary nodule detection in chest radiography by reducing the contrast of overlying bone structures. Recent development of a fast, high-efficiency detector enables dual-energy imaging to be integrated into the traditional workflow. We have modified a GE RevolutionTM XQ/i chest imaging system to construct a dual-energy imaging prototype system. Here we describe the operating characteristics of this prototype and evaluate image quality. Empirical results show that the dual-energy CNR is maximized if the dose is approximately equal for both high and low energy exposures. Given the high detector DQE, and allocation of dose between the two views, we can acquire dual-energy PA and conventional lateral images with total dose equivalent to a conventional two-view film chest exam. Calculations have shown that the dual-exposure technique has superior CNR and tissue cancellation than single-exposure CR systems. Clinical images obtained on a prototype dual-energy imaging system show excellent tissue contrast cancellation, low noise, and modest motion artefacts. In summary, a prototype dual-energy system has been constructed which enables rapid, dual-exposure imaging of the chest using a commercially available high-efficiency, flat-panel x-ray detector. The quality of the clinical images generated with this prototype exceeds that of CR techniques and demonstrates the potential for improved detection and characterization of lung disease through dual-energy imaging.

Report on accelerated corrosion studies.

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

Mowry, Curtis Dale; Glass, Sarah Jill; Sorensen, Neil Robert

2011-03-01

Sandia National Laboratories (SNL) conducted accelerated atmospheric corrosion testing for the U.S. Consumer Product Safety Commission (CPSC) to help further the understanding of the development of corrosion products on conductor materials in household electrical components exposed to environmental conditions representative of homes constructed with problem drywall. The conditions of the accelerated testing were chosen to produce corrosion product growth that would be consistent with long-term exposure to environments containing humidity and parts per billion (ppb) levels of hydrogen sulfide (H{sub 2}S) that are thought to have been the source of corrosion in electrical components from affected homes. This report documentsmore » the test set-up, monitoring of electrical performance of powered electrical components during the exposure, and the materials characterization conducted on wires, screws, and contact plates from selected electrical components. No degradation in electrical performance (measured via voltage drop) was measured during the course of the 8-week exposure, which was approximately equivalent to 40 years of exposure in a light industrial environment. Analyses show that corrosion products consisting of various phases of copper sulfide, copper sulfate, and copper oxide are found on exposed surfaces of the conductor materials including wires, screws, and contact plates. The morphology and the thickness of the corrosion products showed a range of character. In some of the copper wires that were observed, corrosion product had flaked or spalled off the surface, exposing fresh metal to the reaction with the contaminant gasses; however, there was no significant change in the wire cross-sectional area.« less

Laser-based irradiation apparatus and method to measure the functional dose-rate response of semiconductor devices

DOEpatents

Horn, Kevin M [Albuquerque, NM

2008-05-20

A broad-beam laser irradiation apparatus can measure the parametric or functional response of a semiconductor device to exposure to dose-rate equivalent infrared laser light. Comparisons of dose-rate response from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems can determine if aging has affected the device's overall functionality. The dependence of these changes on equivalent dose-rate pulse intensity and/or duration can be measured with the apparatus. The synchronized introduction of external electrical transients into the device under test can be used to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure while exposing the device to dose-rate equivalent infrared laser light.

Down-regulation of muscarinic receptors and the m3 subtype in white-footed mice by dietary exposure to parathion

USGS Publications Warehouse

Jett, David A.; Hill, E.F.; Fernando, J.C.; Eldefrawi, M.E.; Eldefrawi, A.T.

1993-01-01

The effect of ad libitum dietary exposure (as occurs in the field) to parathion for 14 d was investigated on the muscarinic acetylcholine receptor (mAChR) in brains and submaxillary glands of adults of a field species, the white-footed mouse Peromyscus leucopus. Immunoprecipitation using subtype selective antibodies revealed that the relative ratios of the m1-m5 mAChR subtypes in Peromyscus brain were similar to those in rat brain. There was little variability in acetylcholinesterase (AChE) activity in control mice brains but large variability in 39 exposed mice, resulting from differences in food ingestion and parathion metabolism. Accordingly, data on radioligand binding to mAChRs in each mouse brain were correlated with brain AChE activity in the same mouse, and AChE inhibition served as a biomarker of exposure reflecting in situ paraoxon concentrations. Exposure to parathion for 14 d reduced maximal binding (Bmax) of [3H]quinuclidinyl benzilate ([3H]QNB), [3H]-N-methylscopolamine ([3H]NMS), and [3H]-4-diphenylacetoxy-N-methylpiperidine methiodide ([3H]-4-DAMP) by up to approximately 58% without affecting receptor affinities for these ligands. Maximal reduction in Bmax of [3H]QNB and [3H]-4-DAMP binding occurred in mice with highest AChE inhibition, while equivalent maximal reduction in Bmax of [3H]NMS occurred in mice with only approximately 10% AChE inhibition, without further change at higher parathion doses. This is believed to be due to the hydrophilicity of [3H]NMS, which limits its accessibility to internalized desensitized receptors. In submaxillary glands (mAChRs are predominantly m3 subtype), there were significant dose-dependent reductions in [3H]QNB binding and m3 mRNA levels in exposed mice, revealed by Northern blot analyses. The reduction in m3 receptors is suggested to result mostly from reduced synthesis at the transcription level, rather than from translational or posttranslational events. The data suggest that down-regulation of mAChRs occurs after dietary exposure for 14 d to sublethal concentrations of parathion in a field rodent species, and that significant though incomplete recovery in AChE and mAChRs occurs in 7 d following termination of exposure.

EFFECTS OF POND CHARACTERISTICS ON BIOTIC EXPOSURES

EPA Science Inventory

Different aquatic communities, although apparently equivalent, can exhibit a variety of responses when challenged with the same initial total toxicant concentration. ifferences in realized actual exposure concentrations can result from differences in physical morphology, water an...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

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

Husain, Mainul, E-mail: mainul.husain@hc-sc.gc.ca; Kyjovska, Zdenka O., E-mail: zky@nrcwe.dk; Bourdon-Lacombe, Julie, E-mail: julie.bourdon-lacombe@hc-sc.gc.ca

Inhalation of carbon black nanoparticles (CBNPs) causes pulmonary inflammation; however, time course data to evaluate the detailed evolution of lung inflammatory responses are lacking. Here we establish a time-series of lung inflammatory response to CBNPs. Female C57BL/6 mice were intratracheally instilled with 162 μg CBNPs alongside vehicle controls. Lung tissues were examined 3 h, and 1, 2, 3, 4, 5, 14, and 42 days (d) post-exposure. Global gene expression and pulmonary inflammation were assessed. DNA damage was evaluated in bronchoalveolar lavage (BAL) cells and lung tissue using the comet assay. Increased neutrophil influx was observed at all time-points. DNA strandmore » breaks were increased in BAL cells 3 h post-exposure, and in lung tissues 2–5 d post-exposure. Approximately 2600 genes were differentially expressed (± 1.5 fold; p ≤ 0.05) across all time-points in the lungs of exposed mice. Altered transcript levels were associated with immune-inflammatory response and acute phase response pathways, consistent with the BAL profiles and expression changes found in common respiratory infectious diseases. Genes involved in DNA repair, apoptosis, cell cycle regulation, and muscle contraction were also differentially expressed. Gene expression changes associated with inflammatory response followed a biphasic pattern, with initial changes at 3 h post-exposure declining to base-levels by 3 d, increasing again at 14 d, and then persisting to 42 d post-exposure. Thus, this single CBNP exposure that was equivalent to nine 8-h working days at the current Danish occupational exposure limit induced biphasic inflammatory response in gene expression that lasted until 42 d post-exposure, raising concern over the chronic effects of CBNP exposure. - Highlights: • A single exposure to CBNPs induced expression changes in over 2600 genes in mouse lungs. • Altered genes were associated with immune-inflammatory and acute phase responses. • Several genes were involved in DNA repair, apoptosis, and muscle contraction. • Effects of a single exposure to CBNPs lasted until 42 d post-exposure. • A single exposure to CBNPs induced a biphasic inflammatory response in gene expression.« less

Cognate status and cross-script translation priming.

PubMed

Voga, Madeleine; Grainger, Jonathan

2007-07-01

Greek-French bilinguals were tested in three masked priming experiments with Greek primes and French targets. Related primes were the translation equivalents of target words, morphologically related to targets, or phonologically related to targets. In Experiment 1, cognate translation equivalents (phonologically similar translations) showed facilitatory priming, relative to matched phonologically related primes, in conditions in which morphologically related primes showed no effect (50-msec prime exposure). Cross-language morphological priming emerged at longer prime exposure durations (66 msec), but cognate primes continued to generate more priming than did those in the morphological condition. In Experiments 2 and 3, the level of phonological overlap across translation equivalents was varied, and priming effects were measured against those for matched phonologically related primes and those in an unrelated prime condition. When measured against the unrelated baseline, cognate primes showed the typical advantage over noncognate primes. However, this cognate advantage disappeared when priming was measured against the phonologically related prime condition. The results are discussed in terms of how translation equivalents are represented in bilingual memory.

On twelve types of covering-based rough sets.

PubMed

Safari, Samira; Hooshmandasl, Mohammad Reza

2016-01-01

Covering approximation spaces are a generalization of equivalence-based rough set theories. In this paper, we will consider twelve types of covering based approximation operators by combining four types of covering lower approximation operators and three types of covering upper approximation operators. Then, we will study the properties of these new pairs and show they have most of the common properties among existing covering approximation pairs. Finally, the relation between these new pairs is studied.

Opportunities to improve the in vivo measurement of manganese in human hands.

PubMed

Aslam; Chettle, D R; Pejović-Milić, A; Waker, A J

2009-01-07

Manganese (Mn) is an element which is both essential for regulating neurological and skeletal functions in the human body and also toxic when humans are exposed to excessive levels. Its excessive inhalation as a result of exposure through industrial and environmental emissions can cause neurological damage, which may manifest as memory deficit, loss of motor control and reduction in the refinement of certain body motions. A number of clinical studies demonstrate that biological monitoring of Mn exposure using body fluids, particularly blood, plasma/serum and urine is of very limited use and reflect only the most recent exposure and rapidly return to within normal ranges. In this context, a non-invasive neutron activation technique has been developed at the McMaster University accelerator laboratory that could provide an alternative to measure manganese stored in the bones of exposed subjects. In a first pilot study we conducted recently on non-exposed human subjects to measure the ratio of Mn to Ca in hand bones, it was determined that the technique needed further development to improve the precision of the measurements. It could be achieved by improving the minimum detection limit (MDL) of the system from 2.1 microg Mn/g Ca to the reference value of 0.6 microg g(-1) Ca (range: 0.16-0.78 microg Mn/g Ca) for the non-exposed population. However, the developed procedure might still be a suitable means of screening patients and people exposed to excessive amounts of Mn, who could develop many-fold increased levels of Mn in bones as demonstrated through various animal studies. To improve the MDL of the technique to the expected levels of Mn in a reference population, the present study investigates further optimization of irradiation conditions, which includes the optimal selection of proton beam energy, beam current and irradiation time and the effect of upgrading the 4pi detection system. The maximum local dose equivalent that could be given to the hand as a result of irradiation was constrained to be less than 150 mSv as opposed to the previously imposed dose equivalent limit of 20 mSv. A maximum beam current, which could be delivered on the lithium target to produce neutrons, was restricted to 500 microA. The length of irradiation intervals larger than 10 min, was considered inconvenient and impractical to implement with Mn measurements in humans. To fulfil the requirements for developing a protocol for in vivo bone Mn measurements, a revised estimate of the dose equivalent has been presented here. Beam energy of 1.98 MeV was determined to be optimal to complete the irradiation procedure within 10 min using 500 microA beam current. The local dose equivalent given to hand was estimated as 118 mSv, which is lower by a factor of 1.5 compared to that of 2.00 MeV. The optimized beam parameters are expected to improve the currently obtained detection limit of 2.1 microg Mn/g Ca to 0.6 microg Mn/g Ca. Using this dose equivalent delivered to the central location of the hand, the average dose equivalent to the hand of 74 mSv and an effective dose of approximately 70 microSv will be accompanying the non-invasive, in vivo measurements of bone Mn, which is little over the chest radiograph examination dose.

Opportunities to improve the in vivo measurement of manganese in human hands

NASA Astrophysics Data System (ADS)

Aslam; Chettle, D. R.; Pejović-Milić, A.; Waker, A. J.

2009-01-01

Manganese (Mn) is an element which is both essential for regulating neurological and skeletal functions in the human body and also toxic when humans are exposed to excessive levels. Its excessive inhalation as a result of exposure through industrial and environmental emissions can cause neurological damage, which may manifest as memory deficit, loss of motor control and reduction in the refinement of certain body motions. A number of clinical studies demonstrate that biological monitoring of Mn exposure using body fluids, particularly blood, plasma/serum and urine is of very limited use and reflect only the most recent exposure and rapidly return to within normal ranges. In this context, a non-invasive neutron activation technique has been developed at the McMaster University accelerator laboratory that could provide an alternative to measure manganese stored in the bones of exposed subjects. In a first pilot study we conducted recently on non-exposed human subjects to measure the ratio of Mn to Ca in hand bones, it was determined that the technique needed further development to improve the precision of the measurements. It could be achieved by improving the minimum detection limit (MDL) of the system from 2.1 µg Mn/g Ca to the reference value of 0.6 µg g-1 Ca (range: 0.16-0.78 µg Mn/g Ca) for the non-exposed population. However, the developed procedure might still be a suitable means of screening patients and people exposed to excessive amounts of Mn, who could develop many-fold increased levels of Mn in bones as demonstrated through various animal studies. To improve the MDL of the technique to the expected levels of Mn in a reference population, the present study investigates further optimization of irradiation conditions, which includes the optimal selection of proton beam energy, beam current and irradiation time and the effect of upgrading the 4π detection system. The maximum local dose equivalent that could be given to the hand as a result of irradiation was constrained to be less than 150 mSv as opposed to the previously imposed dose equivalent limit of 20 mSv. A maximum beam current, which could be delivered on the lithium target to produce neutrons, was restricted to 500 µA. The length of irradiation intervals larger than 10 min, was considered inconvenient and impractical to implement with Mn measurements in humans. To fulfil the requirements for developing a protocol for in vivo bone Mn measurements, a revised estimate of the dose equivalent has been presented here. Beam energy of 1.98 MeV was determined to be optimal to complete the irradiation procedure within 10 min using 500 µA beam current. The local dose equivalent given to hand was estimated as 118 mSv, which is lower by a factor of 1.5 compared to that of 2.00 MeV. The optimized beam parameters are expected to improve the currently obtained detection limit of 2.1 µg Mn/g Ca to 0.6 µg Mn/g Ca. Using this dose equivalent delivered to the central location of the hand, the average dose equivalent to the hand of 74 mSv and an effective dose of approximately 70 µSv will be accompanying the non-invasive, in vivo measurements of bone Mn, which is little over the chest radiograph examination dose.

High-intensity intermittent exercise increases pulmonary interstitial edema at altitude but not at simulated altitude.

PubMed

Edsell, Mark E; Wimalasena, Yashvi H; Malein, William L; Ashdown, Kimberly M; Gallagher, Carla A; Imray, Chris H; Wright, Alex D; Myers, Stephen D

2014-12-01

Ascent to high altitude leads to a reduction in ambient pressure and a subsequent fall in available oxygen. The resulting hypoxia can lead to elevated pulmonary artery (PA) pressure, capillary stress, and an increase in interstitial fluid. This fluid can be assessed on lung ultrasound (LUS) by the presence of B-lines. We undertook a chamber and field study to assess the impact of high-intensity exercise in hypoxia on the development of pulmonary interstitial edema in healthy lowlanders. Thirteen volunteers completed a high-intensity intermittent exercise (HIIE) test at sea level, in acute normobaric hypoxia (12% O2, approximately 4090 m equivalent altitude), and in hypobaric hypoxia during a field study at 4090 m after 6 days of acclimatization. Pulmonary interstitial edema was assessed by the evaluation of LUS B-lines. After HIIE, no increase in B-lines was seen in normoxia, and a small increase was seen in acute normobaric hypoxia (2 ± 2; P < .05). During the field study at 4090 m, 12 participants (92%) demonstrated 7 ± 4 B-lines at rest, which increased to 17 ± 5 immediately after the exercise test (P < .001). An increase was evident in all participants. There was a reciprocal fall in peripheral arterial oxygen saturations (Spo2) after exercise from 88% ± 4% to 80% ± 8% (P < .01). B-lines and Spo2 in all participants returned to baseline levels within 4 hours. HIIE led to an increase in B-lines at altitude after subacute exposure but not during acute exposure at equivalent simulated altitude. This may indicate pulmonary interstitial edema. Copyright © 2014 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Evaluation of HIFU-induced lesion region using temperature threshold and equivalent thermal dose methods

NASA Astrophysics Data System (ADS)

Chang, Shihui; Xue, Fanfan; Zhou, Wenzheng; Zhang, Ji; Jian, Xiqi

2017-03-01

Usually, numerical simulation is used to predict the acoustic filed and temperature distribution of high intensity focused ultrasound (HIFU). In this paper, the simulated lesion volumes obtained by temperature threshold (TRT) 60 °C and equivalent thermal dose (ETD) 240 min were compared with the experimental results which were obtained by animal tissue experiment in vitro. In the simulation, the calculated model was established according to the vitro tissue experiment, and the Finite Difference Time Domain (FDTD) method was used to calculate the acoustic field and temperature distribution in bovine liver by the Westervelt formula and Pennes bio-heat transfer equation, and the non-linear characteristics of the ultrasound was considered. In the experiment, the fresh bovine liver was exposed for 8s, 10s, 12s under different power conditions (150W, 170W, 190W, 210W), and the exposure was repeated 6 times under the same dose. After the exposures, the liver was sliced and photographed every 0.2mm, and the area of the lesion region in every photo was calculated. Then, every value of the areas was multiplied by 0.2mm, and summed to get the approximation volume of the lesion region. The comparison result shows that the lesion volume of the region calculated by TRT 60 °C in simulation was much closer to the lesion volume obtained in experiment, and the volume of the region above 60 °C was larger than the experimental results, but the volume deviation was not exceed 10%. The volume of the lesion region calculated by ETD 240 min was larger than that calculated by TRT 60 °C in simulation, and the volume deviations were ranged from 4.9% to 23.7%.

A novel concept for CT with fixed anodes (FACT): Medical imaging based on the feasibility of thermal load capacity.

PubMed

Kellermeier, Markus; Bert, Christoph; Müller, Reinhold G

2015-07-01

Focussing primarily on thermal load capacity, we describe the performance of a novel fixed anode CT (FACT) compared with a 100 kW reference CT. Being a fixed system, FACT has no focal spot blurring of the X-ray source during projection. Monte Carlo and finite element methods were used to determine the fluence proportional to thermal capacity. Studies of repeated short-time exposures showed that FACT could operate in pulsed mode for an unlimited period. A virtual model for FACT was constructed to analyse various temporal sequences for the X-ray source ring, representing a circular array of 1160 fixed anodes in the gantry. Assuming similar detector properties at a very small integration time, image quality was investigated using an image reconstruction library. Our model showed that approximately 60 gantry rounds per second, i.e. 60 sequential targetings of the 1160 anodes per second, were required to achieve a performance level equivalent to that of the reference CT (relative performance, RP = 1) at equivalent image quality. The optimal projection duration in each direction was about 10 μs. With a beam pause of 1 μs between projections, 78.4 gantry rounds per second with consecutive source activity were thermally possible at a given thermal focal spot. The settings allowed for a 1.3-fold (RP = 1.3) shorter scan time than conventional CT while maintaining radiation exposure and image quality. Based on the high number of rounds, FACT supports a high image frame rate at low doses, which would be beneficial in a wide range of diagnostic and technical applications. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Comparative pharmacokinetic study of mangiferin after oral administration of pure mangiferin and US patented polyherbal formulation to rats.

PubMed

Kammalla, Ananth Kumar; Ramasamy, Mohan Kumar; Inampudi, Jyothi; Dubey, Govind Prasad; Agrawal, Aruna; Kaliappan, Ilango

2015-04-01

The US patented polyherbal formulation for the prevention and management of type II diabetes and its vascular complications was used for the present study. The xanthone glycoside mangiferin is one of the major effector constituents in the Salacia species with potential anti-diabetic activity. The pharmacokinetic differences of mangiferin following oral administration of pure mangiferin and polyherbal formulation containing Salacia species were studied with approximately the same dose 30 mg/kg mangiferin and its distribution among the major tissue in Wistar rats. Plasma samples were collected at different time points (15, 30, 60, 120, 180, 240, 360, 480, 600, 1,440, 2,160, and 2880 min) and subsequently analyzed using a validated simple and rapid LC-MS method. Plasma concentration versus time profiles were explored by non-compartmental analysis. Mangiferin plasma exposure was significantly increased when administered from formulation compared to the standard mangiferin. Mangiferin resided significantly longer in the body (last mean residence time (MRTlast)) when given in the form of the formulation (3.65 h). Cmax values of formulation (44.16 μg/mL) administration were elevated when compared to equivalent dose of the pure mangiferin (15.23 μg/mL). Tissue distribution study of mangiferin from polyherbal formulation was also studied. In conclusion, the exposure of mangiferin is enhanced after formulation and administration and could result in superior efficacy of polyherbal formulation when compared to an equivalent dose of mangiferin. The results indicate that the reason which delays the elimination of mangiferin and enhances its bioavailability might the interactions of the some other constituents present in the polyherbal formulation. Distribution study results indicate that mangiferin was extensively bound to the various tissues like the small intestine, heart, kidney, spleen, and liver except brain tissue.

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2013 CFR

2013-04-01

... grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in dough conditioning. (c) It is used or intended for...

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2010 CFR

2010-04-01

... grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in dough conditioning. (c) It is used or intended for...

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2011 CFR

2011-04-01

... grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in dough conditioning. (c) It is used or intended for...

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2012 CFR

2012-04-01

... grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in dough conditioning. (c) It is used or intended for...

EXPOSURE TO ENVIRONMENTALLY RELEVANT CONCENTRATIONS OF DIFFERENT NONYLPHENOL FORMULATIONS IN JAPANESE MEDAKA

EPA Science Inventory

The time course of exposure to p-nonylphenol (NP) from two different sources was compared to equivalent exposures of 17-b-estradiol (E2) and a solvent control (ethanol: EtOH). Japanese medaka were exposed for 4 days to a nominal concentration of 20 ?g/l of either NP-I (Schenectad...

Secondhand tobacco smoke exposure differentially alters nucleus tractus solitarius neurons at two different ages in developing non-human primates

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

Sekizawa, Shin-ichi, E-mail: ssekizawa@ucdavis.ed; Joad, Jesse P.; Pinkerton, Kent E.

Exposing children to secondhand tobacco smoke (SHS) is associated with increased risk for asthma, bronchiolitis and SIDS. The role for changes in the developing CNS contributing to these problems has not been fully explored. We used rhesus macaques to test the hypothesis that SHS exposure during development triggers neuroplastic changes in the nucleus tractus solitarius (NTS), where lung sensory information related to changes in airway and lung function is first integrated. Pregnant monkeys were exposed to filtered air (FA) or SHS for 6 h/day, 5 days/week starting at 50-day gestational age. Mother/infant pairs continued the exposures postnatally to age 3more » or 13 months, which may be equivalent to approximately 1 or 4 years of human age, respectively. Whole-cell recordings were made of second-order NTS neurons in transverse brainstem slices. To target the consequences of SHS exposure based on neuronal subgroups, we classified NTS neurons into two phenotypes, rapid-onset spiking (RS) and delayed-onset spiking (DS), and then evaluated intrinsic and synaptic excitabilities in FA-exposed animals. RS neurons showed greater cell excitability especially at age of 3 months while DS neurons received greater amplitudes of excitatory postsynaptic currents (EPSCs). Developmental neuroplasticity such as increases in intrinsic and synaptic excitabilities were detected especially in DS neurons. In 3 month olds, SHS exposure effects were limited to excitatory changes in RS neurons, specifically increases in evoked EPSC amplitudes and increased spiking responses accompanied by shortened action potential width. By 13 months, the continued SHS exposure inhibited DS neuronal activity; decreases in evoked EPSC amplitudes and blunted spiking responses accompanied by prolonged action potential width. The influence of SHS exposure on age-related and phenotype specific changes may be associated with age-specific respiratory problems, for which SHS exposure can increase the risk, such as SIDS and bronchiolitis in infants and asthma in older children.« less

Secondhand tobacco smoke exposure differentially alters nucleus tractus solitarius neurons at two different ages in developing non-human primates.

PubMed

Sekizawa, Shin-Ichi; Joad, Jesse P; Pinkerton, Kent E; Bonham, Ann C

2010-01-15

Exposing children to secondhand tobacco smoke (SHS) is associated with increased risk for asthma, bronchiolitis and SIDS. The role for changes in the developing CNS contributing to these problems has not been fully explored. We used rhesus macaques to test the hypothesis that SHS exposure during development triggers neuroplastic changes in the nucleus tractus solitarius (NTS), where lung sensory information related to changes in airway and lung function is first integrated. Pregnant monkeys were exposed to filtered air (FA) or SHS for 6 h/day, 5 days/week starting at 50-day gestational age. Mother/infant pairs continued the exposures postnatally to age 3 or 13 months, which may be equivalent to approximately 1 or 4 years of human age, respectively. Whole-cell recordings were made of second-order NTS neurons in transverse brainstem slices. To target the consequences of SHS exposure based on neuronal subgroups, we classified NTS neurons into two phenotypes, rapid-onset spiking (RS) and delayed-onset spiking (DS), and then evaluated intrinsic and synaptic excitabilities in FA-exposed animals. RS neurons showed greater cell excitability especially at age of 3 months while DS neurons received greater amplitudes of excitatory postsynaptic currents (EPSCs). Developmental neuroplasticity such as increases in intrinsic and synaptic excitabilities were detected especially in DS neurons. In 3 month olds, SHS exposure effects were limited to excitatory changes in RS neurons, specifically increases in evoked EPSC amplitudes and increased spiking responses accompanied by shortened action potential width. By 13 months, the continued SHS exposure inhibited DS neuronal activity; decreases in evoked EPSC amplitudes and blunted spiking responses accompanied by prolonged action potential width. The influence of SHS exposure on age-related and phenotype specific changes may be associated with age-specific respiratory problems, for which SHS exposure can increase the risk, such as SIDS and bronchiolitis in infants and asthma in older children.

Effects of third trimester-equivalent ethanol exposure on Cl(-) co-transporter expression, network activity, and GABAergic transmission in the CA3 hippocampal region of neonatal rats.

PubMed

Everett, Julie C; Licón-Muñoz, Yamhilette; Valenzuela, C Fernando

2012-09-01

Fetal alcohol spectrum disorders are often associated with structural and functional hippocampal abnormalities, leading to long-lasting learning and memory deficits. The mechanisms underlying these abnormalities are not fully understood. Here, we investigated whether ethanol exposure during the 3rd trimester-equivalent period alters spontaneous network activity that is involved in neuronal circuit development in the CA3 hippocampal region. This activity is driven by GABA(A) receptors, which can have excitatory actions in developing neurons as a consequence of greater expression of the Cl(-) importer, NKCC1, with respect to expression of the Cl(-) exporter, KCC2, resulting in high [Cl(-)](i). Rat pups were exposed to ethanol vapor from postnatal day (P) 2-16 (4 h/day). Weight gain was significantly reduced in pups exposed to ethanol compared to control at P15 and 16. Brain slices were prepared immediately after the end of the 4-h exposure on P4-16 and experiments were also performed under ethanol-free conditions at the end of the exposure paradigm (P17-22). Ethanol exposure did not significantly affect expression of KCC2 or NKCC1, nor did it affect network activity in the CA3 hippocampal region. Ethanol exposure significantly decreased the frequency (at P9-11) and increased the amplitude (at P5-8 and P17-21) of GABA(A) receptor-mediated miniature postsynaptic currents. These data suggest that repeated in vivo exposure to ethanol during the 3rd trimester-equivalent period alters GABAergic transmission in the CA3 hippocampal region, an effect that could lead to abnormal circuit maturation and perhaps contribute to the pathophysiology of fetal alcohol spectrum disorders. Copyright © 2012 Elsevier Inc. All rights reserved.

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

Estimating human-equivalent no observed adverse-effect levels for VOCs (volatile organic compounds) based on minimal knowledge of physiological parameters. Technical paper

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

Overton, J.H.; Jarabek, A.M.

1989-01-01

The U.S. EPA advocates the assessment of health-effects data and calculation of inhaled reference doses as benchmark values for gauging systemic toxicity to inhaled gases. The assessment often requires an inter- or intra-species dose extrapolation from no observed adverse effect level (NOAEL) exposure concentrations in animals to human equivalent NOAEL exposure concentrations. To achieve this, a dosimetric extrapolation procedure was developed based on the form or type of equations that describe the uptake and disposition of inhaled volatile organic compounds (VOCs) in physiologically-based pharmacokinetic (PB-PK) models. The procedure assumes allometric scaling of most physiological parameters and that the value ofmore » the time-integrated human arterial-blood concentration must be limited to no more than to that of experimental animals. The scaling assumption replaces the need for most parameter values and allows the derivation of a simple formula for dose extrapolation of VOCs that gives equivalent or more-conservative exposure concentrations values than those that would be obtained using a PB-PK model in which scaling was assumed.« less

Radiation Exposure of Interventional Radiologists During Computed Tomography Fluoroscopy-Guided Renal Cryoablation and Lung Radiofrequency Ablation: Direct Measurement in a Clinical Setting.

PubMed

Matsui, Yusuke; Hiraki, Takao; Gobara, Hideo; Iguchi, Toshihiro; Fujiwara, Hiroyasu; Kawabata, Takahiro; Yamauchi, Takatsugu; Yamaguchi, Takuya; Kanazawa, Susumu

2016-06-01

Computed tomography (CT) fluoroscopy-guided renal cryoablation and lung radiofrequency ablation (RFA) have received increasing attention as promising cancer therapies. Although radiation exposure of interventional radiologists during these procedures is an important concern, data on operator exposure are lacking. Radiation dose to interventional radiologists during CT fluoroscopy-guided renal cryoablation (n = 20) and lung RFA (n = 20) was measured prospectively in a clinical setting. Effective dose to the operator was calculated from the 1-cm dose equivalent measured on the neck outside the lead apron, and on the left chest inside the lead apron, using electronic dosimeters. Equivalent dose to the operator's finger skin was measured using thermoluminescent dosimeter rings. The mean (median) effective dose to the operator per procedure was 6.05 (4.52) μSv during renal cryoablation and 0.74 (0.55) μSv during lung RFA. The mean (median) equivalent dose to the operator's finger skin per procedure was 2.1 (2.1) mSv during renal cryoablation, and 0.3 (0.3) mSv during lung RFA. Radiation dose to interventional radiologists during renal cryoablation and lung RFA were at an acceptable level, and in line with recommended dose limits for occupational radiation exposure.

Repeated intermittent alcohol exposure during the third trimester-equivalent increases expression of the GABA(A) receptor δ subunit in cerebellar granule neurons and delays motor development in rats.

PubMed

Diaz, Marvin R; Vollmer, Cyndel C; Zamudio-Bulcock, Paula A; Vollmer, William; Blomquist, Samantha L; Morton, Russell A; Everett, Julie C; Zurek, Agnieszka A; Yu, Jieying; Orser, Beverley A; Valenzuela, C Fernando

2014-04-01

Exposure to ethanol (EtOH) during fetal development can lead to long-lasting alterations, including deficits in fine motor skills and motor learning. Studies suggest that these are, in part, a consequence of cerebellar damage. Cerebellar granule neurons (CGNs) are the gateway of information into the cerebellar cortex. Functionally, CGNs are heavily regulated by phasic and tonic GABAergic inhibition from Golgi cell interneurons; however, the effect of EtOH exposure on the development of GABAergic transmission in immature CGNs has not been investigated. To model EtOH exposure during the 3rd trimester-equivalent of human pregnancy, neonatal pups were exposed intermittently to high levels of vaporized EtOH from postnatal day (P) 2 to P12. This exposure gradually increased pup serum EtOH concentrations (SECs) to ∼60 mM (∼0.28 g/dl) during the 4 h of exposure. EtOH levels gradually decreased to baseline 8 h after the end of exposure. Surprisingly, basal tonic and phasic GABAergic currents in CGNs were not significantly affected by postnatal alcohol exposure (PAE). However, PAE increased δ subunit expression at P28 as detected by immunohistochemical and western blot analyses. Also, electrophysiological studies with an agonist that is highly selective for δ-containing GABA(A) receptors, 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridine-3-ol (THIP), showed an increase in THIP-induced tonic current. Behavioral studies of PAE rats did not reveal any deficits in motor coordination, except for a delay in the acquisition of the mid-air righting reflex that was apparent at P15 to P18. These findings demonstrate that repeated intermittent exposure to high levels of EtOH during the equivalent of the last trimester of human pregnancy has significant but relatively subtle effects on motor coordination and GABAergic transmission in CGNs in rats. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluation of annual exposure to noise among private farmers on selected family farms of animal production profile.

PubMed

Solecki, Leszek

2005-01-01

The aim of the study was the recognition and evaluation of annual exposure to noise among private farmers on family farms of animal production profile. The study covered 16 family farms using arable land of the size of 14-50 ha (25.8 ha on average), equipped with agricultural tractors (working with a set of agricultural machines), machines for the production of fodder, workshop machines and woodworking saws. Based on the precise working time schedules concerning agricultural activities and dosimetric measurements conducted during the whole year, two acoustic parameters were determined: total exposure in individual months and equivalent daily exposure. The study showed that the highest values of the total monthly exposure to noise occurred in two summer-autumn months (August, October) and during four winter-spring months (January, March, and May, June). High values of the total exposure observed in the summer-autumn season result from the performance of intensive field and transport work activities, with prolonged duration of work and a large number of workdays in these months. The occurrence of high total values of the total exposure in winter-spring months, however, is associated with logging wood for winter (saws) and intensive repair work activities. In the seasons of the year analysed, high values of equivalent daily exposure were obtained, within the range: 4.20-4.86 Pa(2) x h. The average value of this parameter for the whole year reached the value: 3.61 Pa(2) x h (standard exceeded 3.6 times). This value is equivalent to the mean level of exposure to noise equal to 90.5 dB. In consideration of the moderate accuracy of mean values obtained and small degree of variability of the results, the data acquired in this study may be used in practice by proper State services for the evaluation of noise risk among private farmers specializing in animal production.

Dosimetric models of the eye and lens of the eye and their use in assessing dose coefficients for ocular exposures.

PubMed

Bolch, W E; Dietze, G; Petoussi-Henss, N; Zankl, M

2015-06-01

Based upon recent epidemiological studies of ocular exposure, the Main Commission of the International Commission on Radiological Protection (ICRP) in ICRP Publication 118 states that the threshold dose for radiation-induced cataracts is now considered to be approximately 0.5 Gy for both acute and fractionated exposures. Consequently, a reduction was also recommended for the occupational annual equivalent dose to the lens of the eye from 150 mSv to 20 mSv, averaged over defined periods of 5 years. To support ocular dose assessment and optimisation, Committee 2 included Annex F within ICRP Publication 116 . Annex F provides dose coefficients - absorbed dose per particle fluence - for photon, electron, and neutron irradiation of the eye and lens of the eye using two dosimetric models. The first approach uses the reference adult male and female voxel phantoms of ICRP Publication 110. The second approach uses the stylised eye model of Behrens et al., which itself is based on ocular dimensional data given in Charles and Brown. This article will review the data and models of Annex F with particular emphasis on how these models treat tissue regions thought to be associated with stem cells at risk. © The International Society for Prosthetics and Orthotics Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Shallow-Water Nitrox Diving, the NASA Experience

NASA Technical Reports Server (NTRS)

Fitzpatrick, Daniel T.

2009-01-01

NASA s Neutral Buoyancy Laboratory (NBL) contains a 6.2 million gallon, 12-meter deep pool where astronauts prepare for space missions involving space walks (extravehicular activity EVA). Training is conducted in a space suit (extravehicular mobility unit EMU) pressurized to 4.0 - 4.3 PSI for up to 6.5 hours while breathing a 46% NITROX mix. Since the facility opened in 1997, over 30,000 hours of suited training has been completed with no occurrence of decompression sickness (DCS) or oxygen toxicity. This study examines the last 5 years of astronaut suited training runs. All suited runs are computer monitored and data is recorded in the Environmental Control System (ECS) database. Astronaut training runs from 2004 - 2008 were reviewed and specific data including total run time, maximum depth and average depth were analyzed. One hundred twenty seven astronauts and cosmonauts completed 2,231 training runs totaling 12,880 exposure hours. Data was available for 96% of the runs. It was revealed that the suit configuration produces a maximum equivalent air depth of 7 meters, essentially eliminating the risk of DCS. Based on average run depth and time, approximately 17% of the training runs exceeded the NOAA oxygen maximum single exposure limits, with no resulting oxygen toxicity. The NBL suited training protocols are safe and time tested. Consideration should be given to reevaluate the NOAA oxygen exposure limits for PO2 levels at or below 1 ATA.

EVALUATING TOOLS AND MODELS USED FOR QUANTITATIVE EXTRAPOLATION OF IN VITRO TO IN VIVO DATA FOR NEUROTOXICANTS

EPA Science Inventory

Comparisons of high throughput screening data to human exposures assume that media concentrations are equivalent to steady-state blood concentrations. This assumes the partitioning of the chemical between media and cells is equivalent to the partitioning of the chemical between b...

Mercury, food webs, and marine mammals: implications of diet and climate change for human health.

PubMed

Booth, Shawn; Zeller, Dirk

2005-05-01

We modeled the flow of methyl mercury, a toxic global pollutant, in the Faroe Islands marine ecosystem and compared average human methyl mercury exposure from consumption of pilot whale meat and fish (cod, Gadus morhua) with current tolerable weekly intake (TWI) levels. Under present conditions and climate change scenarios, methyl mercury increased in the ecosystem, translating into increased human exposure over time. However, we saw greater changes as a result of changing fishing mortalities. A large portion of the general human population exceed the TWI levels set by the World Health Organization [WHO; 1.6 microg/kg body weight (bw)], and they all exceed the reference dose (RfD) of 0.1 microg/kg bw/day set by the U.S. Environmental Protection Agency (EPA; equivalent to a TWI of 0.7 microg/kg bw). As a result of an independent study documenting that Faroese children exposed prenatally to methyl mercury had reduced cognitive abilities, pregnant women have decreased their intake of whale meat and were below the TWI levels set by the WHO and the U.S. EPA. Cod had approximately 95% lower methyl mercury concentrations than did pilot whale. Thus, the high and harmful levels of methyl mercury in the diet of Faroe Islanders are driven by whale meat consumption, and the increasing impact of climate change is likely to exacerbate this situation. Significantly, base inflow rates of mercury into the environment would need to be reduced by approximately 50% to ensure levels of intake below the WHO TWI levels, given current levels of whale consumption.

Near Identifiability of Dynamical Systems

NASA Technical Reports Server (NTRS)

Hadaegh, F. Y.; Bekey, G. A.

1987-01-01

Concepts regarding approximate mathematical models treated rigorously. Paper presents new results in analysis of structural identifiability, equivalence, and near equivalence between mathematical models and physical processes they represent. Helps establish rigorous mathematical basis for concepts related to structural identifiability and equivalence revealing fundamental requirements, tacit assumptions, and sources of error. "Structural identifiability," as used by workers in this field, loosely translates as meaning ability to specify unique mathematical model and set of model parameters that accurately predict behavior of corresponding physical system.

Galactic and solar radiation exposure to aircrew during a solar cycle.

PubMed

Lewis, B J; Bennett, L G I; Green, A R; McCall, M J; Ellaschuk, B; Butler, A; Pierre, M

2002-01-01

An on-going investigation using a tissue-equivalent proportional counter (TEPC) has been carried out to measure the ambient dose equivalent rate of the cosmic radiation exposure of aircrew during a solar cycle. A semi-empirical model has been derived from these data to allow for the interpolation of the dose rate for any global position. The model has been extended to an altitude of up to 32 km with further measurements made on board aircraft and several balloon flights. The effects of changing solar modulation during the solar cycle are characterised by correlating the dose rate data to different solar potential models. Through integration of the dose-rate function over a great circle flight path or between given waypoints, a Predictive Code for Aircrew Radiation Exposure (PCAIRE) has been further developed for estimation of the route dose from galactic cosmic radiation exposure. This estimate is provided in units of ambient dose equivalent as well as effective dose, based on E/H x (10) scaling functions as determined from transport code calculations with LUIN and FLUKA. This experimentally based treatment has also been compared with the CARI-6 and EPCARD codes that are derived solely from theoretical transport calculations. Using TEPC measurements taken aboard the International Space Station, ground based neutron monitoring, GOES satellite data and transport code analysis, an empirical model has been further proposed for estimation of aircrew exposure during solar particle events. This model has been compared to results obtained during recent solar flare events.

Relative source allocation of TDI to drinking water for derivation of a criterion for chloroform: a Monte-Carlo and multi-exposure assessment.

PubMed

Niizuma, Shun; Matsui, Yoshihiko; Ohno, Koichi; Itoh, Sadahiko; Matsushita, Taku; Shirasaki, Nobutaka

2013-10-01

Drinking water quality standard (DWQS) criteria for chemicals for which there is a threshold for toxicity are derived by allocating a fraction of tolerable daily intake (TDI) to exposure from drinking water. We conducted physiologically based pharmacokinetic model simulations for chloroform and have proposed an equation for total oral-equivalent potential intake via three routes (oral ingestion, inhalation, and dermal exposures), the biologically effective doses of which were converted to oral-equivalent potential intakes. The probability distributions of total oral-equivalent potential intake in Japanese people were estimated by Monte Carlo simulations. Even when the chloroform concentration in drinking water equaled the current DWQS criterion, there was sufficient margin between the intake and the TDI: the probability that the intake exceeded TDI was below 0.1%. If a criterion that the 95th percentile estimate equals the TDI is regarded as both providing protection to highly exposed persons and leaving a reasonable margin of exposure relative to the TDI, then the chloroform drinking water criterion could be a concentration of 0.11mg/L. This implies a daily intake equal to 34% of the TDI allocated to the oral intake (2L/d) of drinking water for typical adults. For the highly exposed persons, inhalation exposure via evaporation from water contributed 53% of the total intake, whereas dermal absorption contributed only 3%. Copyright © 2013 Elsevier Inc. All rights reserved.

Biological and health effects of exposure to kerosene-based jet fuels and performance additives.

PubMed

Ritchie, Glenn; Still, Kenneth; Rossi, John; Bekkedal, Marni; Bobb, Andrew; Arfsten, Darryl

2003-01-01

Over 2 million military and civilian personnel per year (over 1 million in the United States) are occupationally exposed, respectively, to jet propulsion fuel-8 (JP-8), JP-8 +100 or JP-5, or to the civil aviation equivalents Jet A or Jet A-1. Approximately 60 billion gallon of these kerosene-based jet fuels are annually consumed worldwide (26 billion gallon in the United States), including over 5 billion gallon of JP-8 by the militaries of the United States and other NATO countries. JP-8, for example, represents the largest single chemical exposure in the U.S. military (2.53 billion gallon in 2000), while Jet A and A-1 are among the most common sources of nonmilitary occupational chemical exposure. Although more recent figures were not available, approximately 4.06 billion gallon of kerosene per se were consumed in the United States in 1990 (IARC, 1992). These exposures may occur repeatedly to raw fuel, vapor phase, aerosol phase, or fuel combustion exhaust by dermal absorption, pulmonary inhalation, or oral ingestion routes. Additionally, the public may be repeatedly exposed to lower levels of jet fuel vapor/aerosol or to fuel combustion products through atmospheric contamination, or to raw fuel constituents by contact with contaminated groundwater or soil. Kerosene-based hydrocarbon fuels are complex mixtures of up to 260+ aliphatic and aromatic hydrocarbon compounds (C(6) -C(17+); possibly 2000+ isomeric forms), including varying concentrations of potential toxicants such as benzene, n-hexane, toluene, xylenes, trimethylpentane, methoxyethanol, naphthalenes (including polycyclic aromatic hydrocarbons [PAHs], and certain other C(9)-C(12) fractions (i.e., n-propylbenzene, trimethylbenzene isomers). While hydrocarbon fuel exposures occur typically at concentrations below current permissible exposure limits (PELs) for the parent fuel or its constituent chemicals, it is unknown whether additive or synergistic interactions among hydrocarbon constituents, up to six performance additives, and other environmental exposure factors may result in unpredicted toxicity. While there is little epidemiological evidence for fuel-induced death, cancer, or other serious organic disease in fuel-exposed workers, large numbers of self-reported health complaints in this cohort appear to justify study of more subtle health consequences. A number of recently published studies reported acute or persisting biological or health effects from acute, subchronic, or chronic exposure of humans or animals to kerosene-based hydrocarbon fuels, to constituent chemicals of these fuels, or to fuel combustion products. This review provides an in-depth summary of human, animal, and in vitro studies of biological or health effects from exposure to JP-8, JP-8 +100, JP-5, Jet A, Jet A-1, or kerosene.

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2014 CFR

2014-04-01

... may be mixed with an edible carrier to give a concentration of: (1) 3 grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus...

46 CFR 72.05-25 - Doors, other than watertight.

Code of Federal Regulations, 2011 CFR

2011-10-01

... glass shall be fitted in steel or equivalent metal frames and shall be retained by steel or equivalent metal glazing beads or angles. (5) Where wire-inserted glass is required, and the single wire type is.... The cut for the hose port should be approximately 6 inches square. A hinged or pivoted steel or...

46 CFR 72.05-25 - Doors, other than watertight.

Code of Federal Regulations, 2010 CFR

2010-10-01

... glass shall be fitted in steel or equivalent metal frames and shall be retained by steel or equivalent metal glazing beads or angles. (5) Where wire-inserted glass is required, and the single wire type is.... The cut for the hose port should be approximately 6 inches square. A hinged or pivoted steel or...

Free Fall and the Equivalence Principle Revisited

ERIC Educational Resources Information Center

Pendrill, Ann-Marie

2017-01-01

Free fall is commonly discussed as an example of the equivalence principle, in the context of a homogeneous gravitational field, which is a reasonable approximation for small test masses falling moderate distances. Newton's law of gravity provides a generalisation to larger distances, and also brings in an inhomogeneity in the gravitational field.…

Equivalent electron fluence for space qualification of shallow junction heteroface GaAs solar cells

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Stock, L. V.

1984-01-01

It is desirable to perform qualification tests prior to deployment of solar cells in space power applications. Such test procedures are complicated by the complex mixture of differing radiation components in space which are difficult to simulate in ground test facilities. Although it has been shown that an equivalent electron fluence ratio cannot be uniquely defined for monoenergetic proton exposure of GaAs shallow junction cells, an equivalent electron fluence test can be defined for common spectral components of protons found in space. Equivalent electron fluence levels for the geosynchronous environment are presented.

Tissue disposition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in maternal and developing long-evans rats following subchronic exposure.

PubMed

Hurst, C H; DeVito, M J; Birnbaum, L S

2000-10-01

Prenatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) produces alterations in the reproductive system of the developing pups. The objective of this study was to determine the disposition of TCDD in maternal and fetal Long-Evans (LE) rats following subchronic exposure, since the adverse reproductive and developmental effects have been extensively characterized in this strain of rat. LE rats were dosed by gavage with 1, 10, or 30 ng [(3)H]TCDD/kg in corn oil, 5 days/week for 13 weeks. At the end of 13 weeks, females were mated and dosing continued every day throughout gestation. Dams were sacrificed on gestation day (GD) 9, GD16, GD21, and post-natal day 4 and analyzed for [(3)H]TCDD-derived activity in maternal and fetal tissues. Maternal body burdens were equivalent at different time points, indicating that the dams were at steady state. Maternal body burdens were approximately 19, 120, and 300 ng TCDD/kg following doses of 1, 10, and 30 ng TCDD/kg, respectively. Individual embryo concentrations on GD9 were 1.6, 7, and 16 pg TCDD/g after maternal exposure of 1, 10, and 30 ng/kg/d, respectively. On GD 16, fetal liver, urogenital tract, head, and body concentrations were similar and averaged 1.4, 7.8, and 16.4 pg TCDD/g after administration of 1, 10, or 30 ng TCDD/kg/d, respectively, indicating no preferential sequestration within the different fetal tissues. These concentrations of TCDD within fetal tissues after subchronic exposure are comparable to those seen after a single dose of 50, 200, or 1000 ng TCDD/kg administered on GD15, a critical period of gestation.

The effects of acoustical refurbishment of classrooms on teachers' perceived noise exposure and noise-related health symptoms.

PubMed

Kristiansen, Jesper; Lund, Søren Peter; Persson, Roger; Challi, Rasmus; Lindskov, Janni Moon; Nielsen, Per Møberg; Larsen, Per Knudgaard; Toftum, Jørn

2016-02-01

To investigate whether acoustical refurbishment of classrooms for elementary and lower secondary grade pupils affected teachers' perceived noise exposure during teaching and noise-related health symptoms. Two schools (A and B) with a total of 102 teachers were subjected to an acoustical intervention. Accordingly, 36 classrooms (20 and 16 in school A and school B, respectively) were acoustically refurbished and 31 classrooms (16 and 15 in school A and school B, respectively) were not changed. Thirteen classrooms in school A were interim "sham" refurbished. Control measurements of RT and activity sound levels were measured before and after refurbishment. Data on perceived noise exposure, disturbance attributed to different noise sources, voice symptoms, and fatigue after work were collected over a year in a total of six consecutive questionnaires. Refurbished classrooms were associated with lower perceived noise exposure and lower ratings of disturbance attributed to noise from equipment in the class compared with unrefurbished classrooms. No associations between the classroom refurbishment and health symptoms were observed. Before acoustical refurbishment, the mean classroom reverberation time was 0.68 (school A) and 0.57 (school B) and 0.55 s in sham refurbished classrooms. After refurbishment, the RT was approximately 0.4 s in both schools. Activity sound level measurements confirmed that the intervention had reduced the equivalent sound levels during lessons with circa 2 dB(A) in both schools. The acoustical refurbishment was associated with a reduction in classroom reverberation time and activity sound levels in both schools. The acoustical refurbishment was associated with a reduction in the teachers' perceived noise exposure, and reports of disturbance from equipment in the classroom decreased. There was no significant effect of the refurbishment on the teachers' voice symptoms or fatigue after work.

Biological and statistical approaches to predicting human lung cancer risk from silica.

PubMed

Kuempel, E D; Tran, C L; Bailer, A J; Porter, D W; Hubbs, A F; Castranova, V

2001-01-01

Chronic inflammation is a key step in the pathogenesis of particle-elicited fibrosis and lung cancer in rats, and possibly in humans. In this study, we compute the excess risk estimates for lung cancer in humans with occupational exposure to crystalline silica, using both rat and human data, and using both a threshold approach and linear models. From a toxicokinetic/dynamic model fit to lung burden and pulmonary response data from a subchronic inhalation study in rats, we estimated the minimum critical quartz lung burden (Mcrit) associated with reduced pulmonary clearance and increased neutrophilic inflammation. A chronic study in rats was also used to predict the human excess risk of lung cancer at various quartz burdens, including mean Mcrit (0.39 mg/g lung). We used a human kinetic lung model to link the equivalent lung burdens to external exposures in humans. We then computed the excess risk of lung cancer at these external exposures, using data of workers exposed to respirable crystalline silica and using Poisson regression and lifetable analyses. Finally, we compared the lung cancer excess risks estimated from male rat and human data. We found that the rat-based linear model estimates were approximately three times higher than those based on human data (e.g., 2.8% in rats vs. 0.9-1% in humans, at mean Mcrit lung burden or associated mean working lifetime exposure of 0.036 mg/m3). Accounting for variability and uncertainty resulted in 100-1000 times lower estimates of human critical lung burden and airborne exposure. This study illustrates that assumptions about the relevant biological mechanism, animal model, and statistical approach can all influence the magnitude of lung cancer risk estimates in humans exposed to crystalline silica.

An RF dosimeter for independent SAR measurement in MRI scanners

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

Qian, Di; Bottomley, Paul A.; El-Sharkawy, AbdEl-Monem M.

2013-12-15

Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independentmore » SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B{sub 1}) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on average independent of the imaging subject, albeit with fluctuations. Conclusions: Our 3T RF dosimeter and transducers accurately measure RF exposure in body-equivalent loads and provide scanner-independent assessments of whole-body RF power deposition for establishing safety compliance useful for MRI sequence and device testing.« less

Greenhouse gas emissions of different waste treatment options for sector-specific commercial and industrial waste in Germany.

PubMed

Helftewes, Markus; Flamme, Sabine; Nelles, Michael

2012-04-01

This article investigates greenhouse gas (GHG) emissions from commercial and industrial (C&I) waste treatment considering five sector-specific waste compositions and four different treatment scenarios in Germany. Results show that the highest share of CO₂-equivalent emissions can be avoided in each of the analysed industrial sectors if solid recovered fuel (SRF) is produced for co-incineration in cement kilns. Across all industries, emissions of approximately 680 kg CO₂-eq. Mg⁻¹ C&I waste can be avoided on average under this scenario. The combustion of C&I waste in waste incineration plants without any previous mechanical treatment generates the lowest potential to avoid GHG emissions with a value of approximately 50 kg CO₂-eq. Mg⁻¹ C&I waste on average in all industries. If recyclables are sorted, this can save emissions of approximately 280 kg CO₂-eq. Mg⁻¹ C&I waste while the treatment in SRF power plants amounts to savings of approximately 210 kg CO₂-eq. Mg⁻¹ C&I waste. A comparison of the treatment scenarios of the waste from these five sectors shows that waste treatment of the craft sector leads to the lowest CO₂-equivalent reduction rates of all scenarios. In contrast, the treatment of waste from catering sector leads to the highest CO₂-equivalent reduction rates except for direct incineration in waste incineration plants. The sensitivity analysis of the different scenarios for this paper shows that the efficiency and the substitution factor of energy have a relevant influence on the result. Changes in the substitution factor of 10% can result in changes in emissions of approximately 55 to 75 kg CO₂-eq. Mg⁻¹ in waste incineration plants and approximately 90 kg CO₂-eq. Mg⁻¹ in the case of cement kilns.

Metrics for Labeled Markov Systems

NASA Technical Reports Server (NTRS)

Desharnais, Josee; Jagadeesan, Radha; Gupta, Vineet; Panangaden, Prakash

1999-01-01

Partial Labeled Markov Chains are simultaneously generalizations of process algebra and of traditional Markov chains. They provide a foundation for interacting discrete probabilistic systems, the interaction being synchronization on labels as in process algebra. Existing notions of process equivalence are too sensitive to the exact probabilities of various transitions. This paper addresses contextual reasoning principles for reasoning about more robust notions of "approximate" equivalence between concurrent interacting probabilistic systems. The present results indicate that:We develop a family of metrics between partial labeled Markov chains to formalize the notion of distance between processes. We show that processes at distance zero are bisimilar. We describe a decision procedure to compute the distance between two processes. We show that reasoning about approximate equivalence can be done compositionally by showing that process combinators do not increase distance. We introduce an asymptotic metric to capture asymptotic properties of Markov chains; and show that parallel composition does not increase asymptotic distance.

Studies on the inhalation toxicology of two fiberglasses and amosite asbestos in the syrian golden hamster. Part I. Results of a subchronic study and dose selection for a chronic study.

PubMed

Hesterberg, T W; Axten, C; McConnell, E E; Hart, G A; Miiller, W; Chevalier, J; Everitt, J; Thevenaz, P; Oberdörster, G

1999-09-01

A multidose, subchronic inhalation study was used to estimate the maximum tolerated dose (MTD) of 901 fiberglass (MMVF10.1) for a chronic inhalation study using hamsters. Subchronic study results indicated that 30 mg/m(3) [250-300 WHO fibers (>5 microm long)/cm(3) and 100-130 fibers/cm(3) >20 microm long] meets or exceeds the estimated MTD, and chronic study results confirmed this. For the subchronic study, hamsters were exposed 6 h/day, 5 days/wk, for 13 wk to MMVF10.1 at 3, 16, 30, 45, and 60 mg/m(3) (36, 206, 316, 552, or 714 WHO fibers/cm(3)), then monitored for 10 wk. Results demonstrating MTD were: inflammatory response (all fiber exposures); elevated lung cell proliferation with @ges;16 mg/m(3); lung lavage neutrophil elevations with @ges;16 mg/m(3) and lactate dehydrogenase (LDH) and protein elevations with > or = 30 mg/m(3); and persistent abnormal macrophage/fiber clumps in lungs exposed to 45 and 60 mg/m(3), which suggest overloading of clearance mechanisms. For the chronic study, hamsters were exposed for 78 wk to MMVF10a (901 fiber glass) or MMVF33 (special-application 475 fiberglass) at approximately 300 WHO fibers/cm(3) ( approximately 100 fibers/cm(3) @gt;20 @mu;m long), or to amosite asbestos at an equivalent concentration and 2 lower concentrations. All fiber-exposed animals had pulmonary inflammation, elevated lung lavage cells, and increased lung cell proliferation. Between 52 and 78 wk of exposure, lung burdens of all fibers increased at an accelerated rate, suggesting impairment of clearance mechanisms. MMVF33 and amosite induced fibrosis and pleural mesothelioma. These findings substantiate that exposures in the chronic study adequately tested the toxic potential of fiberglass.

Spatial contrast sensitivity at twilight: luminance, monocularity, and oxygenation.

PubMed

Connolly, Desmond M

2010-05-01

Visual performance in dim light is compromised by lack of oxygen (hypoxia). The possible influence of altered oxygenation on foveal contrast sensitivity under mesopic (twilight) viewing conditions is relevant to aircrew flying at night, including when using night vision devices, but is poorly documented. Foveal contrast sensitivity was measured binocularly and monocularly in 12 subjects at 7 spatial frequencies, ranging from 0.5 to approximately 16 cycles per degree, using sinusoidal Gabor patch gratings. Hypoxic performance breathing 14.1% oxygen, equivalent to altitude exposure at 3048 m (10,000 ft), was compared with breathing air at sea level (normoxia) at low photopic (28 cd x m(-2)), borderline upper mesopic (approximately 2.1 cd x m(-2)) and midmesopic (approximately 0.26 cd x m(-2)) luminance. Mesopic performance was also assessed breathing 100% oxygen (hyperoxia). Typical 'inverted U' log/log plots of the contrast sensitivity function were obtained, with elevated thresholds (reduced sensitivity) at lower luminance. Binocular viewing enhanced sensitivity by a factor approximating square root of 2 for most conditions, supporting neural summation of the contrast signal, but had greater influence at the lowest light level and highest spatial frequencies (8.26 and 16.51 cpd). Respiratory challenges had no effect. Contrast sensitivity is poorer when viewing monocularly and especially at midmesopic luminance, with relevance to night flying. The foveal contrast sensitivity function is unaffected by respiratory disturbance when twilight conditions favor cone vision, despite known effects on retinal illumination (pupil size). The resilience of the contrast sensitivity function belies the vulnerability of foveal low contrast acuity to mild hypoxia at mesopic luminance.

Assessment of the in vitro dermal irritation potential of cerium, silver, and titanium nanoparticles in a human skin equivalent model

EPA Science Inventory

AbstractDermal exposure to metals may res·ult in irritant contact dermatitis. This study examined the potential of metal nanoparticles to elicit irritant contact dermatitis in a human skin equivalent model (HSEM) derived from epidermal keratinocytes. These cultured cells form a m...

A pilot study of the photoprotective effect of almond phytochemicals in a 3D human skin equivalent

USDA-ARS?s Scientific Manuscript database

UV exposure causes oxidative stress, inflammation, erythema, and skin cancer. Alpha-Tocopherol (AT) and polyphenols (AP) present in almonds may serve as photoprotectants. Our objectives were to assess the feasibility of using a 3D human skin equivalent (HSE) in photoprotectant research and to deter...

Polybrominated diphenyl ethers in indoor dust in Ottawa, Canada: implications for sources and exposure.

PubMed

Wilford, Bryony H; Shoeib, Mahiba; Harner, Tom; Zhu, Jiping; Jones, Kevin C

2005-09-15

Polybrominated diphenyl ethers (PBDEs) are widely used as additive flame retardants in plastics, soft furnishings, electrical and electronic equipment, and insulation in the indoor environment, and may be released indoors via volatilization or as dusts. The penta-and octa-brominated mixes are now banned in most parts of Europe, and phasing out of their use has recently begun in North America. This study follows a previous investigation into indoor air levels of PBDEs. House dust was analyzed from the family vacuum cleaners of 68 of the same 74 randomly selected homes, in Ottawa, Canada during the winter of 2002-2003. PBDEs, comprising on average 42% BDE-209, were found in all samples. The levels were log-normally distributed with a geometric mean sigmaPBDE of 2000 ng g(-1), and a median of 1800 ng g(-1) dust. The levels in dust did not correlate with questionnaire information on house characteristics. Correlations were found between pentamix congener levels in dust and in air from the same homes, but not for congeners of the more highly brominated mixes. Exposure scenarios are presented for mean and high dust ingestion rates, and compared against exposures from other pathways, for both adults and toddlers (6 months-2 years). Assuming a mean dust ingestion rate and median dust and air concentrations, adults would be exposed to ca. 7.5 ng sigmaPBDE d(-1) via the dust ingestion pathway, which represents approximately 14% of total daily exposure when compared to diet (82%) and inhalation (4%). However, for toddlers the equivalent intakes would be 99 ng d(-1), representing 80% of their daily PBDE exposure. At high dust ingestion rates these values increase to 180 ng d(-1) (80% daily intake) for adults and 360 ng d(-1) (89% daily intake) for toddlers. The data give a clearer picture of sources of PBDE exposure in the home environment and suggest that dust could be a significant exposure pathway for some individuals, particularly children.

The flux of small near-Earth objects colliding with the Earth.

PubMed

Brown, P; Spalding, R E; ReVelle, D O; Tagliaferri, E; Worden, S P

2002-11-21

Asteroids with diameters smaller than approximately 50-100 m that collide with the Earth usually do not hit the ground as a single body; rather, they detonate in the atmosphere. These small objects can still cause considerable damage, such as occurred near Tunguska, Siberia, in 1908. The flux of small bodies is poorly constrained, however, in part because ground-based observational searches pursue strategies that lead them preferentially to find larger objects. A Tunguska-class event-the energy of which we take to be equivalent to 10 megatons of TNT-was previously estimated to occur every 200-300 years, with the largest annual airburst calculated to be approximately 20 kilotons (kton) TNT equivalent (ref. 4). Here we report satellite records of bolide detonations in the atmosphere over the past 8.5 years. We find that the flux of objects in the 1-10-m size range has the same power-law distribution as bodies with diameters >50 m. From this we estimate that the Earth is hit on average annually by an object with approximately 5 kton equivalent energy, and that Tunguska-like events occur about once every 1,000 years.

Cumulative exposure to lead and cognition in persons with Parkinson's disease.

PubMed

Weuve, Jennifer; Press, Daniel Z; Grodstein, Francine; Wright, Robert O; Hu, Howard; Weisskopf, Marc G

2013-02-01

Dementia is an important consequence of Parkinson's disease (PD), with few known modifiable risk factors. Cumulative exposure to lead, at levels experienced in the community, may exacerbate PD-related neural dysfunction, resulting in impaired cognition. Among 101 persons with PD ("cases") and, separately, 50 persons without PD ("controls"), we evaluated cumulative lead exposure, gauged by tibia and patella bone lead concentrations, in relation to cognitive function, assessed using a telephone battery developed and validated in a separate sample of PD patients. We also assessed the interaction between lead and case-control status. After multivariable adjustment, higher tibia bone lead concentration among PD cases was associated with worse performance on all of the individual telephone tests. In particular, tibia lead levels corresponded to significantly worse performance on a telephone analog of the Mini-Mental State Examination and tests of working memory and attention. Moreover, higher tibia bone lead concentration was associated with significantly worse global composite score encompassing all the cognitive tests (P = 0.04). The magnitude of association per standard deviation increment in tibia bone lead level was equivalent to the difference in global scores among controls in our study, who were approximately 7 years apart in age. The tibia lead-cognition association was notably stronger within cases than within controls (P(difference) = 0.06). Patella bone lead concentration was not consistently associated with performance on the tests. These data provide evidence suggesting that cumulative exposure to lead may result in worsened cognition among persons with PD. Copyright © 2012 Movement Disorders Society.

Pharmacokinetic Evaluation of the Equivalency of Gavage, Dietary, and Drinking Water Exposure to Manganese in F344 Rats

PubMed Central

Foster, Melanie L.; Bartnikas, Thomas B.; Johnson, Laura C.; Herrera, Carolina; Pettiglio, Michael A.; Keene, Athena M.; Taylor, Michael D.; Dorman, David C.

2015-01-01

Concerns exist as to whether individuals may be at greater risk for neurotoxicity following increased manganese (Mn) oral intake. The goals of this study were to determine the equivalence of 3 methods of oral exposure and the rate (mg Mn/kg/day) of exposure. Adult male rats were allocated to control diet (10 ppm), high manganese diet (200 ppm), manganese-supplemented drinking water, and manganese gavage treatment groups. Animals in the drinking water and gavage groups were given the 10 ppm manganese diet and supplemented with manganese chloride (MnCl2) in drinking water or once-daily gavage to provide a daily manganese intake equivalent to that seen in the high-manganese diet group. No statistically significant difference in body weight gain or terminal body weights was seen. Rats were anesthetized following 7 and 61 exposure days, and samples of bile and blood were collected. Rats were then euthanized and striatum, olfactory bulb, frontal cortex, cerebellum, liver, spleen, and femur samples were collected for chemical analysis. Hematocrit was unaffected by manganese exposure. Liver and bile manganese concentrations were elevated in all treatment groups on day 61 (relative to controls). Increased cerebellum manganese concentrations were seen in animals from the high-manganese diet group (day 61, relative to controls). Increased (relative to all treatment groups) femur, striatum, cerebellum, frontal cortex, and olfactory bulb manganese concentrations were also seen following gavage suggesting that dose rate is an important factor in the pharmacokinetics of oral manganese. These data will be used to refine physiologically based pharmacokinetic models, extending their utility for manganese risk assessment by including multiple dietary exposures. PMID:25724921

[Analysis of annual exposure to noise among private farmers according to production profile].

PubMed

Solecki, Leszek

2007-01-01

The objective of the study was the recognition and evaluation of annual exposure to noise among private farmers on selected family farms of three different profiles of agricultural production (plant, animal and mixed). Based on time schedules of agricultural work activities and dosimetric measurements conducted during the whole year, 2 acoustic parameters were determined: total exposure to noise in individual months of the year and equivalent daily exposure to noise. The studies showed that in the case of farms carrying out plant production the highest value of total exposure to noise occurred during the summer-autumn months (July, September, October) and in winter (December, January). On farms of animal production profile the highest values were noted in summer-autumn months (August, October) and winter-spring months (January, March, May, June). On mixed production farms high values occurred in summer-autumn months (August-November) and in April. The distribution of equivalent daily exposure values during the whole year was similar. The results of the study indicated that the greatest noise load occurs on farms carrying out plant and mixed production, whereas the lowest values concerned farms of animal production profile. These values considerably exceed standard values.

A comparison of quantum limited dose and noise equivalent dose

NASA Astrophysics Data System (ADS)

Job, Isaias D.; Boyce, Sarah J.; Petrillo, Michael J.; Zhou, Kungang

2016-03-01

Quantum-limited-dose (QLD) and noise-equivalent-dose (NED) are performance metrics often used interchangeably. Although the metrics are related, they are not equivalent unless the treatment of electronic noise is carefully considered. These metrics are increasingly important to properly characterize the low-dose performance of flat panel detectors (FPDs). A system can be said to be quantum-limited when the Signal-to-noise-ratio (SNR) is proportional to the square-root of x-ray exposure. Recent experiments utilizing three methods to determine the quantum-limited dose range yielded inconsistent results. To investigate the deviation in results, generalized analytical equations are developed to model the image processing and analysis of each method. We test the generalized expression for both radiographic and fluoroscopic detectors. The resulting analysis shows that total noise content of the images processed by each method are inherently different based on their readout scheme. Finally, it will be shown that the NED is equivalent to the instrumentation-noise-equivalent-exposure (INEE) and furthermore that the NED is derived from the quantum-noise-only method of determining QLD. Future investigations will measure quantum-limited performance of radiographic panels with a modified readout scheme to allow for noise improvements similar to measurements performed with fluoroscopic detectors.

Comparing fire spread algorithms using equivalence testing and neutral landscape models

Treesearch

Brian R. Miranda; Brian R. Sturtevant; Jian Yang; Eric J. Gustafson

2009-01-01

We demonstrate a method to evaluate the degree to which a meta-model approximates spatial disturbance processes represented by a more detailed model across a range of landscape conditions, using neutral landscapes and equivalence testing. We illustrate this approach by comparing burn patterns produced by a relatively simple fire spread algorithm with those generated by...

A Nitration Reaction Puzzle for the Organic Chemistry Laboratory

ERIC Educational Resources Information Center

Wieder, Milton J.; Barrows, Russell

2008-01-01

Treatment of phenylacetic acid with 90% HNO[subscript 3] yields a product, I, whose observed melting point is 175-179 degrees C and whose equivalent weight is approximately 226 grams. Treatment of phenylacetic acid with 70% HNO[subscript 3] yields a product, II, whose observed melting point is 106-111 degrees C and whose equivalent weight is…

Greenhouse energy consumption

Treesearch

Eric van Steenis

2009-01-01

Depending on location and luck, natural gas rates have gone from less that CAN$ 3.00 to more than CAN$ 20.00/gigajoule (Gj). Natural gas rates are currently around CAN$ 13.00/Gj, although industry "analysts" predict an increase. A gigajoule is equivalent to the energy released by the combustion of approximately 30 L (8 gal) of gasoline. It is also equivalent...

Perceptual learning improves visual performance in juvenile amblyopia.

PubMed

Li, Roger W; Young, Karen G; Hoenig, Pia; Levi, Dennis M

2005-09-01

To determine whether practicing a position-discrimination task improves visual performance in children with amblyopia and to determine the mechanism(s) of improvement. Five children (age range, 7-10 years) with amblyopia practiced a positional acuity task in which they had to judge which of three pairs of lines was misaligned. Positional noise was produced by distributing the individual patches of each line segment according to a Gaussian probability function. Observers were trained at three noise levels (including 0), with each observer performing between 3000 and 4000 responses in 7 to 10 sessions. Trial-by-trial feedback was provided. Four of the five observers showed significant improvement in positional acuity. In those four observers, on average, positional acuity with no noise improved by approximately 32% and with high noise by approximately 26%. A position-averaging model was used to parse the improvement into an increase in efficiency or a decrease in equivalent input noise. Two observers showed increased efficiency (51% and 117% improvements) with no significant change in equivalent input noise across sessions. The other two observers showed both a decrease in equivalent input noise (18% and 29%) and an increase in efficiency (17% and 71%). All five observers showed substantial improvement in Snellen acuity (approximately 26%) after practice. Perceptual learning can improve visual performance in amblyopic children. The improvement can be parsed into two important factors: decreased equivalent input noise and increased efficiency. Perceptual learning techniques may add an effective new method to the armamentarium of amblyopia treatments.

Out-of-field doses and neutron dose equivalents for electron beams from modern Varian and Elekta linear accelerators.

PubMed

Cardenas, Carlos E; Nitsch, Paige L; Kudchadker, Rajat J; Howell, Rebecca M; Kry, Stephen F

2016-07-08

Out-of-field doses from radiotherapy can cause harmful side effects or eventually lead to secondary cancers. Scattered doses outside the applicator field, neutron source strength values, and neutron dose equivalents have not been broadly investigated for high-energy electron beams. To better understand the extent of these exposures, we measured out-of-field dose characteristics of electron applicators for high-energy electron beams on two Varian 21iXs, a Varian TrueBeam, and an Elekta Versa HD operating at various energy levels. Out-of-field dose profiles and percent depth-dose curves were measured in a Wellhofer water phantom using a Farmer ion chamber. Neutron dose was assessed using a combination of moderator buckets and gold activation foils placed on the treatment couch at various locations in the patient plane on both the Varian 21iX and Elekta Versa HD linear accelerators. Our findings showed that out-of-field electron doses were highest for the highest electron energies. These doses typically decreased with increasing distance from the field edge but showed substantial increases over some distance ranges. The Elekta linear accelerator had higher electron out-of-field doses than the Varian units examined, and the Elekta dose profiles exhibited a second dose peak about 20 to 30 cm from central-axis, which was found to be higher than typical out-of-field doses from photon beams. Electron doses decreased sharply with depth before becoming nearly constant; the dose was found to decrease to a depth of approximately E(MeV)/4 in cm. With respect to neutron dosimetry, Q values and neutron dose equivalents increased with electron beam energy. Neutron contamination from electron beams was found to be much lower than that from photon beams. Even though the neutron dose equivalent for electron beams represented a small portion of neutron doses observed under photon beams, neutron doses from electron beams may need to be considered for special cases.

Acetylator Status Impacts Amifampridine Phosphate (Firdapse™) Pharmacokinetics and Exposure to a Greater Extent Than Renal Function.

PubMed

Haroldsen, Peter E; Sisic, Zlatko; Datt, Joe; Musson, Donald G; Ingenito, Gary

2017-07-01

The purpose of this study is to evaluate safety, tolerability, and pharmacokinetic (PK) properties of amifampridine phosphate (Firdapse™) and its major inactive 3-N-acetyl metabolite in renally impaired and healthy individuals with slow acetylator (SA) and rapid acetylator (RA) phenotypes. This was a Phase I, multicenter, open-label study of the PK properties and safety profile of amifampridine phosphate in individuals with normal, mild, moderate, or severely impaired renal function. Amifampridine phosphate was given as a single 10 mg (base equivalent) dose, and the plasma and urine PK properties of amifampridine and its 3-N-acetyl metabolite were determined. The safety profile was evaluated by monitoring adverse events (AEs), clinical laboratory tests, and physical examinations. Amifampridine clearance was predominantly metabolic through N-acetylation, regardless of renal function in both acetylator phenotypes. In individuals with normal renal function, mean renal clearance represented approximately 3% and 18% of the total clearance of amifampridine in RA and SA, respectively. Large differences in amifampridine exposure were observed between acetylation phenotypes across renal function levels. Mean amifampridine exposure values of AUC 0-∞ and C max were up to 8.8-fold higher in the SA group compared with the RA group across renal function levels. By comparison, mean AUC 0-∞ was less affected by renal function within an acetylator group, only 2- to 3-fold higher in individuals with severe renal impairment (RI) compared with those with normal renal function. Exposure to amifampridine in the SA group with normal renal function was higher (AUC 0-∞, approximately 1.8-fold; C max, approximately 4.1-fold) than the RA group with severe RI. Exposure to the inactive 3-N-acetyl metabolite was higher than amifampridine in both acetylator groups, independent of renal function level. The metabolite is cleared by renal excretion, and exposure was clearly dependent on renal function with 4.0- to 6.8-fold increases in AUC 0-∞ from normal to severe RI. No new tolerability findings were observed. A single dose of 10 mg of amifampridine phosphate was well tolerated, independent of renal function and acetylator status. The results indicate that the PK profile of amifampridine is affected by metabolic acetylator phenotype to a greater extent than by renal function level, supporting Firdapse™ administration in individuals with RI in line with current labeling recommendations. Amifampridine should be dosed to effect per the individual patient need, altering administration frequency and dose in normal through severe RI. The therapeutic dose of amifampridine phosphate should be tailored to the individual patient needs by gradual dose titration up to the present maximum recommended dose (60-80 mg/day) or until dose-limiting AEs intervene to avoid overdosing and underdosing. EudraCT identifier: 2013-005349-35. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

29 CFR 1910.1050 - Methylenedianiline.

Code of Federal Regulations, 2011 CFR

2011-07-01

... determined by any 15 minute sample period. (c) Permissible exposure limits (PEL). The employer shall assure...) Where the employer can document that exposure levels are equivalent for similar operations in different... paragraph (m) of this section, and explain the information contained in appendix C; and (C) Describe the...

14 CFR 150.21 - Noise exposure maps and related descriptions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... TRANSPORTATION (CONTINUED) AIRPORTS AIRPORT NOISE COMPATIBILITY PLANNING Development of Noise Exposure Maps and... concerning future type and frequency of aircraft operations, number of nighttime operations, flight patterns... part, or an FAA approved equivalent, and in consultation with states, and public agencies and planning...

14 CFR 150.21 - Noise exposure maps and related descriptions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... TRANSPORTATION (CONTINUED) AIRPORTS AIRPORT NOISE COMPATIBILITY PLANNING Development of Noise Exposure Maps and... concerning future type and frequency of aircraft operations, number of nighttime operations, flight patterns... part, or an FAA approved equivalent, and in consultation with states, and public agencies and planning...

14 CFR 150.21 - Noise exposure maps and related descriptions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... TRANSPORTATION (CONTINUED) AIRPORTS AIRPORT NOISE COMPATIBILITY PLANNING Development of Noise Exposure Maps and... concerning future type and frequency of aircraft operations, number of nighttime operations, flight patterns... part, or an FAA approved equivalent, and in consultation with states, and public agencies and planning...

14 CFR 150.21 - Noise exposure maps and related descriptions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... TRANSPORTATION (CONTINUED) AIRPORTS AIRPORT NOISE COMPATIBILITY PLANNING Development of Noise Exposure Maps and... concerning future type and frequency of aircraft operations, number of nighttime operations, flight patterns... part, or an FAA approved equivalent, and in consultation with states, and public agencies and planning...

14 CFR 150.21 - Noise exposure maps and related descriptions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... TRANSPORTATION (CONTINUED) AIRPORTS AIRPORT NOISE COMPATIBILITY PLANNING Development of Noise Exposure Maps and... concerning future type and frequency of aircraft operations, number of nighttime operations, flight patterns... part, or an FAA approved equivalent, and in consultation with states, and public agencies and planning...

Investigating the protective properties of milk phospholipids against ultraviolet light exposure in a skin equivalent model

NASA Astrophysics Data System (ADS)

Russell, Ashley; Laubscher, Andrea; Jimenez-Flores, Rafael; Laiho, Lily H.

2010-02-01

Current research on bioactive molecules in milk has documented health advantages of bovine milk and its components. Milk Phospholipids, selected for this study, represent molecules with great potential benefit in human health and nutrition. In this study we used confocal reflectance and multiphoton microscopy to monitor changes in skin morphology upon skin exposure to ultraviolet light and evaluate the potential of milk phospholipids in preventing photodamage to skin equivalent models. The results suggest that milk phospholipids act upon skin cells in a protective manner against the effect of ultraviolet (UV) radiation. Similar results were obtained from MTT tissue viability assay and histology.

The Evolution of Ly-alpha Emitting Galaxies Between z = 2.1 and z = 3.l

NASA Technical Reports Server (NTRS)

Ciardullo, Robin; Gronwall,Caryl; Wolf, Christopher; McCathran, Emily; Bond, Nicholas A.; Gawiser, Eric; Guaita, Lucia; Feldmeier, John J.; Treister, Ezequiel; Padilla, Nelson;

Radiation exposure of the radiologist's eye lens during CT-guided interventions.

PubMed

Heusch, Philipp; Kröpil, Patric; Buchbender, Christian; Aissa, Joel; Lanzman, Rotem S; Heusner, Till A; Ewen, Klaus; Antoch, Gerald; Fürst, Günther

2014-02-01

In the past decade the number of computed tomography (CT)-guided procedures performed by interventional radiologists have increased, leading to a significantly higher radiation exposure of the interventionalist's eye lens. Because of growing concern that there is a stochastic effect for the development of lens opacification, eye lens dose reduction for operators and patients should be of maximal interest. To determine the interventionalist's equivalent eye lens dose during CT-guided interventions and to relate the results to the maximum of the recommended equivalent dose limit. During 89 CT-guided interventions (e.g. biopsies, drainage procedures, etc.) measurements of eye lens' radiation doses were obtained from a dedicated dosimeter system for scattered radiation. The sensor of the personal dosimeter system was clipped onto the side of the lead glasses which was located nearest to the CT gantry. After the procedure, radiation dose (µSv), dose rate (µSv/min) and the total exposure time (s) were recorded. For all 89 interventions, the median total exposure lens dose was 3.3 µSv (range, 0.03-218.9 µSv) for a median exposure time of 26.2 s (range, 1.1-94.0 s). The median dose rate was 13.9 µSv/min (range, 1.1-335.5 µSv/min). Estimating 50-200 CT-guided interventions per year performed by one interventionalist, the median dose of the eye lens of the interventional radiologist does not exceed the maximum of the ICRP-recommended equivalent eye lens dose limit of 20 mSv per year.

Biomonitoring Data for 2,4-Dichlorophenoxyacetic Acid in the United States and Canada: Interpretation in a Public Health Risk Assessment Context Using Biomonitoring Equivalents

EPA Science Inventory

Several extensive studies of exposure to 2,4-dichlorophenoxyacetic acid (2,4-D) using urinary concentrations in samples from the general population, farm applicators, and farm family members are now available. Reference doses (RfDs) exist for 2,4-D, and Biomonitoring Equivalents ...

Personal Dose Equivalent Conversion Coefficients For Photons To 1 GEV

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

Veinot, K. G.; Hertel, N. E.

2010-09-27

The personal dose equivalent, H{sub p}(d), is the quantity recommended by the International Commission on Radiation Units and Measurements (ICRU) to be used as an approximation of the protection quantity Effective Dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body. Typically, the location of interest is the trunk where personal dosemeters are usually worn and in this instance a suitable approximation is a 30 cm X 30 cm X 15 cm slab-type phantom. For this condition the personal dose equivalent is denoted as H{sub p,slab}(d) and the depths,more » d, are taken to be 0.007 cm for non-penetrating and 1 cm for penetrating radiation. In operational radiation protection a third depth, 0.3 cm, is used to approximate the dose to the lens of the eye. A number of conversion coefficients for photons are available for incident energies up to several MeV, however, data to higher energies are limited. In this work conversion coefficients up to 1 GeV have been calculated for H{sub p,slab}(10) and H{sub p,slab}(3) using both the kerma approximation and by tracking secondary charged particles. For H{sub p}(0.07) the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H{sub p,slab}(d) have been determined and are reported. The conversion coefficients were determined for discrete incident energies, but analytical fits of the coefficients over the energy range are provided. Since the inclusion of air can influence the production of secondary charged particles incident on the face of the phantom conversion coefficients have been determined both in vacuo and with the source and slab immersed within a sphere in air. The conversion coefficients for the personal dose equivalent are compared to the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection (ICRP) guidance.« less

Reduced cardiovascular fitness associated with exposure to clozapine in individuals with chronic schizophrenia.

PubMed

Kim, David D; Lang, Donna J; Procyshyn, Ric M; Woodward, Melissa L; Kaufman, Kai; White, Randall F; Honer, William G; Warburton, Darren E R

2018-04-01

Studies show that individuals with schizophrenia have impaired cardiovascular fitness (i.e., low peak aerobic power (VO 2 peak)). It is speculated that antipsychotics with adverse cardiovascular and metabolic profiles, in particular clozapine, have a significant impact on VO 2 peak. In this cross-sectional study, we examined whether exposure to clozapine was associated with further reduced VO 2 peak compared with non-clozapine antipsychotics. Thirty participants with chronic schizophrenia or schizoaffective disorder were divided into clozapine and non-clozapine groups. Mean daily doses of antipsychotics were standardized to chlorpromazine equivalents and haloperidol equivalents for antagonism of alpha 1 - and alpha 2 -adrenergic receptors. Participants completed an incremental-to-maximal symptom-limited exercise test on a cycle ergometer for the assessment of VO 2 peak. The clozapine group demonstrated significantly lower VO 2 peak than the non-clozapine group. Haloperidol equivalents for alpha-adrenergic receptor antagonism, but not chlorpromazine equivalents, demonstrated significant inverse associations with VO 2 peak. The clozapine group had a significantly higher amount of antagonistic activity at alpha-adrenergic receptors than the non-clozapine group. In conclusion, exposure to clozapine was associated with further reduced cardiovascular fitness, which may be explained by the drug's greater antagonistic activity at alpha-adrenergic receptors. Cardiovascular fitness needs to be promoted in individuals treated with antipsychotics, particularly clozapine, to prevent the risk of cardiovascular disease and mortality. Copyright © 2018 Elsevier B.V. All rights reserved.

Dioxin equivalency: Challenge to dose extrapolation

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

Brown, J.F. Jr.; Silkworth, J.B.

1995-12-31

Extensive research has shown that all biological effects of dioxin-like agents are mediated via a single biochemical target, the Ah receptor (AhR), and that the relative biologic potencies of such agents in any given system, coupled with their exposure levels, may be described in terms of toxic equivalents (TEQ). It has also shown that the TEQ sources include not only chlorinated species such as the dioxins (PCDDs), PCDFs, and coplanar PCBs, but also non-chlorinated substances such as the PAHs of wood smoke, the AhR agonists of cooked meat, and the indolocarbazol (ICZ) derived from cruciferous vegetables. Humans have probably hadmore » elevated exposures to these non-chlorinated TEQ sources ever since the discoveries of fire, cooking, and the culinary use of Brassica spp. Recent assays of CYP1A2 induction show that these ``natural`` or ``traditional`` AhR agonists are contributing 50--100 times as much to average human TEQ exposures as do the chlorinated xenobiotics. Currently, the safe doses of the xenobiotic TEQ sources are estimated from their NOAELs and large extrapolation factors, derived from arbitrary mathematical models, whereas the NOAELs themselves are regarded as the safe doses for the TEQs of traditional dietary components. Available scientific data can neither support nor refute either approach to assessing the health risk of an individual chemical substance. However, if two substances be toxicologically equivalent, then their TEQ-adjusted health risks must also be equivalent, and the same dose extrapolation procedure should be used for both.« less

Evaluation of surface modification methods to mitigate rusting and pitting in weathering steel bridges : final report.

DOT National Transportation Integrated Search

1986-09-01

Accelerated laboratory atmospheric exposure simulation tests with an acceleration factor of 50 and extending for a maximum of 2200 wet-dry cycles (6-year exposure equivalent) gave corrosion loss data that agreed fairly well with the field data derive...

USING DOSE ADDITION TO ESTIMATE CUMULATIVE RISKS FROM EXPOSURES TO MULTIPLE CHEMICALS

EPA Science Inventory

The Food Quality Protection Act (FQPA) of 1996 requires the EPA to consider the cumulative risk from exposure to multiple chemicals that have a common mechanism of toxicity. Three methods, hazard index (HI), point-of-departure index (PODI), and toxicity equivalence factor (TEF), ...

Comparing Future Teachers' Beliefs across Countries: Approximate Measurement Invariance with Bayesian Elastic Constraints for Local Item Dependence and Differential Item Functioning

ERIC Educational Resources Information Center

Braeken, Johan; Blömeke, Sigrid

2016-01-01

Using data from the international Teacher Education and Development Study: Learning to Teach Mathematics (TEDS-M), the measurement equivalence of teachers' beliefs across countries is investigated for the case of "mathematics-as-a fixed-ability". Measurement equivalence is a crucial topic in all international large-scale assessments and…

A posteriori error estimation for multi-stage Runge–Kutta IMEX schemes

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

Chaudhry, Jehanzeb H.; Collins, J. B.; Shadid, John N.

Implicit–Explicit (IMEX) schemes are widely used for time integration methods for approximating solutions to a large class of problems. In this work, we develop accurate a posteriori error estimates of a quantity-of-interest for approximations obtained from multi-stage IMEX schemes. This is done by first defining a finite element method that is nodally equivalent to an IMEX scheme, then using typical methods for adjoint-based error estimation. Furthermore, the use of a nodally equivalent finite element method allows a decomposition of the error into multiple components, each describing the effect of a different portion of the method on the total error inmore » a quantity-of-interest.« less

A posteriori error estimation for multi-stage Runge–Kutta IMEX schemes

DOE PAGES

Chaudhry, Jehanzeb H.; Collins, J. B.; Shadid, John N.

2017-02-05

Implicit–Explicit (IMEX) schemes are widely used for time integration methods for approximating solutions to a large class of problems. In this work, we develop accurate a posteriori error estimates of a quantity-of-interest for approximations obtained from multi-stage IMEX schemes. This is done by first defining a finite element method that is nodally equivalent to an IMEX scheme, then using typical methods for adjoint-based error estimation. Furthermore, the use of a nodally equivalent finite element method allows a decomposition of the error into multiple components, each describing the effect of a different portion of the method on the total error inmore » a quantity-of-interest.« less

Spectrophotometry of 2 complete samples of flat radio spectrum quasars

NASA Technical Reports Server (NTRS)

Wampler, E. J.; Gaskell, C. M.; Burke, W. L.; Baldwin, J. A.

1983-01-01

Spectrophotometry of two complete samples of flat-spectrum radio quasars show that for these objects there is a strong correlation between the equivalent width of the CIV wavelength 1550 emission line and the luminosity of the underlying continuum. Assuming Friedmann cosmologies, the scatter in this correlation is a minimum for q (sub o) is approximately 1. Alternatively, luminosity evolution can be invoked to give compact distributions for q (sub o) is approximately 0 models. A sample of Seyfert galaxies observed with IUE shows that despite some dispersion the average equivalent width of CIV wavelength 1550 in Seyfert galaxies is independent of the underlying continuum luminosity. New redshifts for 4 quasars are given.

Characterization of the early pulmonary inflammatory response associated with PTFE fume exposure

NASA Technical Reports Server (NTRS)

Johnston, C. J.; Finkelstein, J. N.; Gelein, R.; Baggs, R.; Oberdorster, G.; Clarkson, T. W. (Principal Investigator)

1996-01-01

Heating of polytetrafluoroethylene (PTFE) has been described to release fumes containing ultrafine particles (approximately 18 nm diam). These fumes can be highly toxic in the respiratory tract inducing extensive pulmonary edema with hemorrhagic inflammation. Fischer-344 rats were exposed to PTFE fumes generated by temperatures ranging from 450 to 460 degrees C for 15 min at an exposure concentration of 5 x 10(5) particles/cm3, equivalent to approximately 50 micrograms/m3. Responses were examined 4 hr post-treatment when these rats demonstrated 60-85% neutrophils (PMNs) in their lung lavage. Increases in abundance for messages encoding the antioxidants manganese superoxide dismutase and metallothionein (MT) increased 15- and 40-fold, respectively. For messages encoding the pro- and anti-inflammatory cytokines: inducible nitric oxide synthase, interleukin 1 alpha, 1 beta, and 6 (IL-1 alpha, IL-1 beta, and IL-6), macrophage inflammatory protein-2, and tumor necrosis factor-alpha (TNF alpha) increases of 5-, 5-, 10-, 40-, 40-, and 15-fold were present. Vascular endothelial growth factor, which may play a role in the integrity of the endothelial barrier, was decreased to 20% of controls. In situ sections were hybridized with 33P cRNA probes encoding IL-6, MT, surfactant protein C, and TNF alpha. Increased mRNA abundance for MT and IL-6 was expressed around all airways and interstitial regions with MT and IL-6 demonstrating similar spatial distribution. Large numbers of activated PMNs expressed IL-6, MT, and TNF alpha. Additionally, pulmonary macrophages and epithelial cells were actively involved. These observations support the notion that PTFE fumes containing ultrafine particles initiate a severe inflammatory response at low inhaled particle mass concentrations, which is suggestive of an oxidative injury. Furthermore, PMNs may actively regulate the inflammatory process through cytokine and antioxidant expression.

Stachybotrys chartarum alters surfactant-related phospholipid synthesis and CTP:cholinephosphate cytidylyltransferase activity in isolated fetal rat type II cells.

PubMed

Hastings, C; Rand, T; Bergen, H T; Thliveris, J A; Shaw, A R; Lombaert, G A; Mantsch, H H; Giles, B L; Dakshinamurti, S; Scott, J E

2005-03-01

Stachybotry chartarum, a fungal contaminant of water-damaged buildings commonly grows on damp cellulose-containing materials. It produces a complex array of mycotoxins. Their mechanisms of action on the pulmonary system are not entirely clear. Previous studies suggest spore products may depress formation of disaturated phosphatidylcholine (DSPC), the major surface-active component of pulmonary surfactant (PS). If S. chartarum can indeed affect formation of this phospholipid, then mold exposure may be a significant issue for pulmonary function in both mature lung and developing fetal lung. To address this possibility, fetal rat type II cells, the principal source of DSPC, were used to assess effects of S. chartarum extract on formation of DSPC. Isolated fetal rat lung type II cells prelabeled with 3H-choline and incubated with spore extract showed decreased incorporation of 3H-choline into DSPC. The activity of CTP:cholinephosphate cytidylyltransferase (CPCT), the rate-limiting enzyme in phosphatidylcholine synthesis was reduced by approximately 50% by a 1:10 dilution of spore extract. Two different S. chartarum extracts (isolates from S. chartarum (Cleveland) and S. chartarum (Hawaiian)) were used to compare activity of CPCT in the presence of phosphatidylglycerol (PG), a known activator. PG produced an approximate two-fold increase in CPCT activity. The spore isolate from Hawaii did not alter enzyme activity. S. chartarum (Cleveland) eliminated the PG-induced activation of CPCT. These results support previous observations that mold products alter PS metabolism and may pose a risk in developing lung, inhibiting surfactant synthesis. Different isolates of the same species of fungus are not equivalent in terms of potential exposure risks.

The limits of applicability of the sound exposure level (SEL) metric to temporal threshold shifts (TTS) in beluga whales, Delphinapterus leucas.

PubMed

Popov, Vladimir V; Supin, Alexander Ya; Rozhnov, Viatcheslav V; Nechaev, Dmitry I; Sysueva, Evgenia V

2014-05-15

The influence of fatiguing sound level and duration on post-exposure temporary threshold shift (TTS) was investigated in two beluga whales (Delphinapterus leucas). The fatiguing sound was half-octave noise with a center frequency of 22.5 kHz. TTS was measured at a test frequency of 32 kHz. Thresholds were measured by recording rhythmic evoked potentials (the envelope following response) to a test series of short (eight cycles) tone pips with a pip rate of 1000 s(-1). TTS increased approximately proportionally to the dB measure of both sound pressure (sound pressure level, SPL) and duration of the fatiguing noise, as a product of these two variables. In particular, when the noise parameters varied in a manner that maintained the product of squared sound pressure and time (sound exposure level, SEL, which is equivalent to the overall noise energy) at a constant level, TTS was not constant. Keeping SEL constant, the highest TTS appeared at an intermediate ratio of SPL to sound duration and decreased at both higher and lower ratios. Multiplication (SPL multiplied by log duration) better described the experimental data than an equal-energy (equal SEL) model. The use of SEL as a sole universal metric may result in an implausible assessment of the impact of a fatiguing sound on hearing thresholds in odontocetes, including under-evaluation of potential risks. © 2014. Published by The Company of Biologists Ltd.

Overview of current TEFs as it relates to current PCB exposures: What is needed?

EPA Science Inventory

The toxic equivalency factor (TEF) approach is one of the ways to assess the risk associated with exposure to complex mixture of polychlorinated biphenyls (PCBs) and structurally related chemicals. This method is based on mode of action with the assumption that all chemicals in ...

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

Rich, B.L.

Measurements of beta and/or nonpenetrating exposure results is complicated and past techniques and capabilities have resulted in significant inaccuracies in recorded results. Current developments have resulted in increased capabilities which make the results more accurate and should result in less total exposure to the work force. Continued development of works in progress should provide equivalent future improvements.

Incorporating High-Throughput Exposure Predictions with Dosimetry-Adjusted In Vitro Bioactivity to Inform Chemical Toxicity Testing

EPA Science Inventory

We previously integrated dosimetry and exposure with high-throughput screening (HTS) to enhance the utility of ToxCast™ HTS data by translating in vitro bioactivity concentrations to oral equivalent doses (OEDs) required to achieve these levels internally. These OEDs were compare...

Evaluation of Biomonitoring Data from the CDC National Exposure Report in a Risk Assessment Context: Perspectives across Chemicals

EPA Science Inventory

BACKGROUND: Biomonitoring data reported in the National Report on Human Exposure to Environmental Chemicals (NER) provide information on the presence and concentrations of more than 400 chemicals in human blood and urine. Biomonitoring Equivalents (BEs) and other risk assessment...

A New Method for Generating Distribution of Biomonitoring Equivalents to Support Exposure Assessment and Prioritization

EPA Science Inventory

Biomonitoring data are now available for hundreds of chemicals through state and national health surveys. Exposure guidance values also exist for many of these chemicals. Several methods are frequently used to evaluate biomarker data with respect to a guidance value. The “biomoni...

Coupled vibration of isotropic metal hollow cylinders with large geometrical dimensions

NASA Astrophysics Data System (ADS)

Lin, Shuyu

2007-08-01

In this paper, the coupled vibration of isotropic metal hollow cylinders with large geometrical dimensions is studied by using an approximate analytic method. According to this method, when the equivalent mechanical coupling coefficient that is defined as the stress ratio is introduced, the coupled vibration of a metal hollow cylinder is reduced to two equivalent one-dimensional vibrations, one is an equivalent longitudinal extensional vibration in the height direction of the cylinder, and the other is an equivalent plane radial vibration in the radius direction. These two equivalent vibrations are coupled to each other by the equivalent mechanical coupling coefficient. The resonance frequency equation of metal hollow cylinders in coupled vibration is derived and longitudinal and radial resonance frequencies are computed. For comparison, the resonance frequencies of the hollow cylinders are also computed by using numerical method. The analysis shows that the results from these two methods are in a good agreement with each other.

Inhalation exposure and risk of polycyclic aromatic hydrocarbons (PAHs) among the rural population adopting wood gasifier stoves compared to different fuel-stove users

NASA Astrophysics Data System (ADS)

Lin, Nan; Chen, Yuanchen; Du, Wei; Shen, Guofeng; Zhu, Xi; Huang, Tianbo; Wang, Xilong; Cheng, Hefa; Liu, Junfeng; Xue, Chunyu; Liu, Guangqing; Zeng, Eddy Y.; Xing, Baoshan; Tao, Shu

2016-12-01

Polycyclic aromatica hydrocarbons (PAHs) are a group of compounds with carcinogenic potentials and residential solid fuel combustion is one major source of PAHs in most developing countries. Replacement of traditional stoves with improved ones is believed to be a practical approach to reduce pollutant emissions, however, field assessments on the performance and consequent impacts on air quality and human health after adopting improved stoves are rare. The study is the first time to quantify inhalation exposure to PAHs among the residents who adopted wood gasifier stoves. The results were compared to those still burning coals in the region and compared to exposure levels for different fuel/stove users in literature. The results showed that the PAHs exposure levels for the wood gasifier stove users were significantly lower than the values for those using traditional wood stoves reported in literature, and the daily exposure concentrations of BaPeq (Benzo[a]pyrene equivalent concentration) can be reduced by 48%-91% if traditional wood stoves were replaced by wood gasifier stoves. The corresponding Incremental Lifetime Cancer Risk (ILCR) decreased approximately four times from 1.94 × 10-4 to 5.17 × 10-5. The average concentration of the total 26 PAHs for the wood users was 1091 ± 722 ng/m3, which was comparable to 1060 ± 927 ng/m3 for those using anthracite coals, but the composition profiles were considerably different. The average BaPeq were 116 and 25.8 ng/m3 for the wood and coal users, respectively, and the corresponding ILCR of the anthracite coal users was 1.69 × 10-5, which was nearly one third of those using the wood gasifier stoves. The wood users exposed to not only high levels of high molecular weight PAHs, but relatively high fractions of particulate phase PAHs in small particles compared to the coal users, resulting in high exposure risks.

Laser-based irradiation apparatus and methods for monitoring the dose-rate response of semiconductor devices

DOEpatents

Horn, Kevin M [Albuquerque, NM

2006-03-28

A scanned, pulsed, focused laser irradiation apparatus can measure and image the photocurrent collection resulting from a dose-rate equivalent exposure to infrared laser light across an entire silicon die. Comparisons of dose-rate response images or time-delay images from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems allows precise identification of those specific age-affected circuit structures within a device that merit further quantitative analysis with targeted materials or electrical testing techniques. Another embodiment of the invention comprises a broad-beam, dose rate-equivalent exposure apparatus. The broad-beam laser irradiation apparatus can determine if aging has affected the device's overall functionality. This embodiment can be combined with the synchronized introduction of external electrical transients into a device under test to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure.

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

Big Stimulus, Little Ears: Safety in Administering Vestibular Evoked Myogenic Potentials (VEMP) in Children

PubMed Central

Thomas, Megan L.A.; Fitzpatrick, Denis; McCreery, Ryan; Janky, Kristen L.

2017-01-01

Background Cervical and ocular Vestibular Evoked Myogenic Potentials (VEMPs) have become common clinical vestibular assessments. However, VEMP testing requires high intensity stimuli, raising concerns regarding safety with children, where sound pressure levels may be higher due to their smaller ear canal volumes. Purpose The purpose of this study was to estimate the range of peak-to-peak equivalent sound pressure levels (peSPLs) in child and adult ears in response to high intensity stimuli (i.e., 100 dB normal hearing level (nHL)) commonly used for VEMP testing and make a determination of whether acoustic stimuli levels with VEMP testing are safe for use in children. Research Design Prospective Experimental. Study Sample Ten children (4–6 years) and ten young adults (24 – 35 years) with normal hearing sensitivity and middle ear function participated in the study. Data Collection and Analysis Probe microphone peSPL measurements of clicks and 500 Hz tonebursts (TBs) were recorded in tubes of small, medium, and large diameter, and in a Brüel & Kjær Ear Simulator Type 4157 to assess for linearity of the stimulus at high levels. The different diameter tubes were used to approximate the range of cross-sectional areas in infant, child, and adult ears, respectively. Equivalent ear canal volume and peSPL measurements were then recorded in child and adult ears. Lower intensity levels were used in the participant’s ears to limit exposure to high intensity sound. The peSPL measurements in participant ears were extrapolated using predictions from linear mixed models to determine if equivalent ear canal volume significantly contributed to overall peSPL and to estimate the mean and 95% confidence intervals of peSPLs in child and adult ears when high intensity stimulus levels (100 dB nHL) are used for VEMP testing without exposing subjects to high-intensity stimuli. Results Measurements from the coupler and tubes suggested: 1) each stimuli was linear, 2) there were no distortions or non-linearities at high levels, and 3) peSPL increased with decreased tube diameter. Measurements in participant ears suggested: 1) peSPL was approximately 3 dB larger in child compared to adult ears, and 2) peSPL was larger in response to clicks compared to 500 Hz TBs. The model predicted the following 95% confidence interval for a 100 dB nHL click: 127–136.5 dB peSPL in adult ears and 128.7–138.2 dB peSPL in child ears. The model predicted the following 95% confidence interval for a 100 dB nHL 500 Hz TB stimulus: 122.2 – 128.2 dB peSPL in adult ears and 124.8–130.8 dB peSPL in child ears. Conclusions Our findings suggest that 1) when completing VEMP testing, the stimulus is approximately 3 dB higher in a child’s ear, 2) a 500 Hz TB is recommended over a click as it has lower peSPL compared to the click, and 3) both duration and intensity should be considered when choosing VEMP stimuli. Calculating the total sound energy exposure for your chosen stimuli is recommended as it accounts for both duration and intensity. When using this calculation for children, consider adding 3 dB to the stimulus level. PMID:28534730

Big Stimulus, Little Ears: Safety in Administering Vestibular-Evoked Myogenic Potentials in Children.

PubMed

Thomas, Megan L A; Fitzpatrick, Denis; McCreery, Ryan; Janky, Kristen L

2017-05-01

Cervical and ocular vestibular-evoked myogenic potentials (VEMPs) have become common clinical vestibular assessments. However, VEMP testing requires high intensity stimuli, raising concerns regarding safety with children, where sound pressure levels may be higher due to their smaller ear canal volumes. The purpose of this study was to estimate the range of peak-to-peak equivalent sound pressure levels (peSPLs) in child and adult ears in response to high intensity stimuli (i.e., 100 dB normal hearing level [nHL]) commonly used for VEMP testing and make a determination of whether acoustic stimuli levels with VEMP testing are safe for use in children. Prospective experimental. Ten children (4-6 years) and ten young adults (24-35 years) with normal hearing sensitivity and middle ear function participated in the study. Probe microphone peSPL measurements of clicks and 500 Hz tonebursts (TBs) were recorded in tubes of small, medium, and large diameter, and in a Brüel & Kjær Ear Simulator Type 4157 to assess for linearity of the stimulus at high levels. The different diameter tubes were used to approximate the range of cross-sectional areas in infant, child, and adult ears, respectively. Equivalent ear canal volume and peSPL measurements were then recorded in child and adult ears. Lower intensity levels were used in the participant's ears to limit exposure to high intensity sound. The peSPL measurements in participant ears were extrapolated using predictions from linear mixed models to determine if equivalent ear canal volume significantly contributed to overall peSPL and to estimate the mean and 95% confidence intervals of peSPLs in child and adult ears when high intensity stimulus levels (100 dB nHL) are used for VEMP testing without exposing subjects to high-intensity stimuli. Measurements from the coupler and tubes suggested: 1) each stimuli was linear, 2) there were no distortions or nonlinearities at high levels, and 3) peSPL increased with decreased tube diameter. Measurements in participant ears suggested: 1) peSPL was approximately 3 dB larger in child compared to adult ears, and 2) peSPL was larger in response to clicks compared to 500 Hz TBs. The model predicted the following 95% confidence interval for a 100 dB nHL click: 127-136.5 dB peSPL in adult ears and 128.7-138.2 dB peSPL in child ears. The model predicted the following 95% confidence interval for a 100 dB nHL 500 Hz TB stimulus: 122.2-128.2 dB peSPL in adult ears and 124.8-130.8 dB peSPL in child ears. Our findings suggest that 1) when completing VEMP testing, the stimulus is approximately 3 dB higher in a child's ear, 2) a 500 Hz TB is recommended over a click as it has lower peSPL compared to the click, and 3) both duration and intensity should be considered when choosing VEMP stimuli. Calculating the total sound energy exposure for your chosen stimuli is recommended as it accounts for both duration and intensity. When using this calculation for children, consider adding 3 dB to the stimulus level. American Academy of Audiology

Equivalent source modeling of the core magnetic field using magsat data

NASA Technical Reports Server (NTRS)

Mayhew, M. A.; Estes, R. H.

1983-01-01

Experiments are carried out on fitting the main field using different numbers of equivalent sources arranged in equal area at fixed radii at and inside the core-mantle boundary. In fixing the radius for a given series of runs, the convergence problems that result from the extreme nonlinearity of the problem when dipole positions are allowed to vary are avoided. Results are presented from a comparison between this approach and the standard spherical harmonic approach for modeling the main field in terms of accuracy and computational efficiency. The modeling of the main field with an equivalent dipole representation is found to be comparable to the standard spherical harmonic approach in accuracy. The 32 deg dipole density (42 dipoles) corresponds approximately to an eleventh degree/order spherical harmonic expansion (143 parameters), whereas the 21 dipole density (92 dipoles) corresponds to approximately a seventeenth degree and order expansion (323 parameters). It is pointed out that fixing the dipole positions results in rapid convergence of the dipole solutions for single-epoch models.

Free fall and the equivalence principle revisited

NASA Astrophysics Data System (ADS)

Pendrill, Ann-Marie

2017-11-01

Free fall is commonly discussed as an example of the equivalence principle, in the context of a homogeneous gravitational field, which is a reasonable approximation for small test masses falling moderate distances. Newton’s law of gravity provides a generalisation to larger distances, and also brings in an inhomogeneity in the gravitational field. In addition, Newton’s third law of action and reaction causes the Earth to accelerate towards the falling object, bringing in a mass dependence in the time required for an object to reach ground—in spite of the equivalence between inertial and gravitational mass. These aspects are rarely discussed in textbooks when the motion of everyday objects are discussed. Although these effects are extremely small, it may still be important for teachers to make assumptions and approximations explicit, to be aware of small corrections, and also to be prepared to estimate their size. Even if the corrections are not part of regular teaching, some students may reflect on them, and their questions deserve to be taken seriously.

Calculation of water equivalent thickness of materials of arbitrary density, elemental composition and thickness in proton beam irradiation

NASA Astrophysics Data System (ADS)

Zhang, Rui; Newhauser, Wayne D.

2009-03-01

In proton therapy, the radiological thickness of a material is commonly expressed in terms of water equivalent thickness (WET) or water equivalent ratio (WER). However, the WET calculations required either iterative numerical methods or approximate methods of unknown accuracy. The objective of this study was to develop a simple deterministic formula to calculate WET values with an accuracy of 1 mm for materials commonly used in proton radiation therapy. Several alternative formulas were derived in which the energy loss was calculated based on the Bragg-Kleeman rule (BK), the Bethe-Bloch equation (BB) or an empirical version of the Bethe-Bloch equation (EBB). Alternative approaches were developed for targets that were 'radiologically thin' or 'thick'. The accuracy of these methods was assessed by comparison to values from an iterative numerical method that utilized evaluated stopping power tables. In addition, we also tested the approximate formula given in the International Atomic Energy Agency's dosimetry code of practice (Technical Report Series No 398, 2000, IAEA, Vienna) and stopping power ratio approximation. The results of these comparisons revealed that most methods were accurate for cases involving thin or low-Z targets. However, only the thick-target formulas provided accurate WET values for targets that were radiologically thick and contained high-Z material.

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

Barr, J.H.; Silha, R.E.; Richards, A.G.

A report of the Radiation Protection Committee of the American Academy of Oral Roentgenology on recommendation for reducing exposure to patient and dentist during oral radiographic procedures is reviewed. The following aspects of the problem of exposure reduction are considered: max permissible exposures to operators and patients, sources of radiation in dental offices, recommended building materials to be used for wall construction (with their lead equivalents), and detailed statements of procedures for protecting operators and patients. (TCO)

Translating Benzodiazepine Utilization Data into Meaningful Population Exposure: Integration of Two Metrics for Improved Reporting.

PubMed

Brandt, Jaden; Alkabanni, Wajd; Alessi-Severini, Silvia; Leong, Christine

2018-04-04

Drug utilization research on benzodiazepines remains important for measuring trends in consumption within and across borders over time for the sake of monitoring prescribing patterns and identifying potential population safety concerns. The defined daily dose (DDD) system by the World Health Organization (WHO) remains the internationally accepted standard for measuring drug consumption; however, beyond consumption, DDD-based results are difficult to interpret when individual agents are compared with one another or are pooled into a total class-based estimate. The diazepam milligram equivalent (DME) system provides approximate conversions between benzodiazepines and Z-drugs (i.e. zopiclone, zolpidem, zaleplon) based on their pharmacologic potency. Despite this, conversion of total dispensed benzodiazepine quantities into DME values retains diazepam milligrams as the total unit of measurement, which is also impractical for population-level interpretation. In this paper, we propose the use of an integrated DME-DDD metric to obviate the limitations encountered when the component metrics are used in isolation. Through a case example, we demonstrate significant change in results between the DDD and DME-DDD method. Unlike the DDD method, the integrated DME-DDD metric offers estimation of population pharmacologic exposure, and enables superior interpretation of drug utilization results, especially for drug class summary reporting.

Evaluation of Biomonitoring Data from the CDC National ...

EPA Pesticide Factsheets

BACKGROUND: Biomonitoring data reported in the National Report on Human Exposure to Environmental Chemicals (NER) provide information on the presence and concentrations of more than 400 chemicals in human blood and urine. Biomonitoring Equivalents (BEs) and other risk assessment-based values now allow interpretation of these biomonitoring data in a public health risk context. OBJECTIVES: Compare the measured biomarker concentrations in the NER with BEs and similar risk assessment values to provide an across-chemical risk assessment perspective on the measured levels for approximately 130 analytes in the NER. METHODS: Available risk assessment-based biomarker screening values, including BEs and Human Biomonitoring-I (HBM-I) values from the German Human Biomonitoring Commission, were identified. Geometric mean and 95th percentile population biomarker concentrations from the NER were compared to the available screening values to generate chemical-specific hazard quotients (HQ) or cancer risk estimates. CONCLUSIONS: Several analytes in the NER approach or exceed HQ values of 1 or cancer risks greater than 1x 10-4 at the geometric mean or 95th percentile, suggesting exposure levels exceed what is considered safe in a large fraction of the population. Analytes of concern include acrylamide, dioxin-like chemicals, benzene, xylene, several metals, di-2(ethylhexyl)phthalate, and some legacy organochlorine pesticides. This analysis provides for the first time a mean

Personal noise exposure assessment from small firearms

NASA Astrophysics Data System (ADS)

Kardous, Chucri A.; Murphy, William J.; Willson, Robert D.

2003-04-01

The National Institute for Occupational Safety and Health conducted noise exposure evaluations of law-enforcement personnel during firearms training at indoor and outdoor firing ranges. A representative cross section of weapons used by officers was measured. Shooters participated in live-fire exercise at an indoor firing range using three different weapons: a Beretta .400 caliber pistol, a Remington 12-gauge shotgun, and an M4 .223-caliber assault rifle. Indoor and outdoor measurements were obtained for the Smith and Wesson .357 pistol and Colt .450 and 9-mm pistols, the Glock .400 pistol, and the Heckler and Koch and Colt AR15 .223 rifles. Impulses were measured using a Bruel and Kjaer 4136 1/4-in. microphone and TASCAM digital audio tape recorder. Relevant impulse noise metrics were calculated. Peak levels ranged from 155 to 168 dB SPL. A-weighted equivalent levels ranged from 124 to 128 dBA. The contributions of the secondary weapon firings were approximately 1 to 9 dBA. Other parameters such as A/B durations, number and mixture of impulses, spectral content, energy, kurtosis, temporal spacing, and hearing protectors' effectiveness were examined. Comparisons of applicable damage risk criteria are presented. Further studies are needed to establish an occupational impulse noise damage risk criterion.

Analysis and probabilistic risk assessment of bioaccessible arsenic in polished and husked jasmine rice sold in Bangkok.

PubMed

Hensawang, Supanad; Chanpiwat, Penradee

2018-09-01

Food is one of the major sources of arsenic (As) exposure in humans. The objectives of this study were to determine the bioaccessible concentration of As in rice grain sold in Bangkok and to evaluate the potential health risks associated with rice consumption. Polished (n = 32) and husked (n = 17) jasmine rice were collected from local markets. In vitro digestion was performed to determine the bioaccessible As concentrations, which were used for probabilistic health risk assessments in different age groups of the population. Approximately 43.0% and 44.4% of the total As in the grain of polished and husked rice, respectively, was in the form of bioaccessible As. Significantly higher bioaccessible As concentrations were found in husked rice than in polished rice (1.5-3.8 times greater). The concentrations of bioaccessible As in polished and husked rice were lower than the Codex standard for As in rice. The average daily dose of As via rice consumption is equivalent to the daily ingestion of 2 L of water containing approximately 3.2-7.2 μg L -1 of As. Approximately 0.2%-13.7% and 10.7%-55.3% of the population may experience non-carcinogenic effects from polished and husked rice consumption, respectively. Approximately 1%-11.6% of children and 74.1%-99.8% of adults were at risk of cancer. The maximum cancer probabilities were 3 children and 6 adults in 10,000 individuals. The probabilistic risk results indicated that children and adults were at risk of both non-carcinogenic and carcinogenic effects from both types of rice consumption. Copyright © 2018 Elsevier Ltd. All rights reserved.

Interim methods for development of inhalation reference concentrations. Draft report

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

Blackburn, K.; Dourson, M.; Erdreich, L.

1990-08-01

An inhalation reference concentration (RfC) is an estimate of continuous inhalation exposure over a human lifetime that is unlikely to pose significant risk of adverse noncancer health effects and serves as a benchmark value for assisting in risk management decisions. Derivation of an RfC involves dose-response assessment of animal data to determine the exposure levels at which no significant increase in the frequency or severity of adverse effects between the exposed population and its appropriate control exists. The assessment requires an interspecies dose extrapolation from a no-observed-adverse-effect level (NOAEL) exposure concentration of an animal to a human equivalent NOAEL (NOAEL(HBC)).more » The RfC is derived from the NOAEL(HBC) by the application of generally order-of-magnitude uncertainty factors. Intermittent exposure scenarios in animals are extrapolated to chronic continuous human exposures. Relationships between external exposures and internal doses depend upon complex simultaneous and consecutive processes of absorption, distribution, metabolism, storage, detoxification, and elimination. To estimate NOAEL(HBC)s when chemical-specific physiologically-based pharmacokinetic models are not available, a dosimetric extrapolation procedure based on anatomical and physiological parameters of the exposed human and animal and the physical parameters of the toxic chemical has been developed which gives equivalent or more conservative exposure concentrations values than those that would be obtained with a PB-PK model.« less

Periodic solutions of second-order nonlinear difference equations containing a small parameter. II - Equivalent linearization

NASA Technical Reports Server (NTRS)

Mickens, R. E.

1985-01-01

The classical method of equivalent linearization is extended to a particular class of nonlinear difference equations. It is shown that the method can be used to obtain an approximation of the periodic solutions of these equations. In particular, the parameters of the limit cycle and the limit points can be determined. Three examples illustrating the method are presented.

Exposure of the examiner to radiation during myelography versus radiculography and root block: A comparative study.

PubMed

Yamane, Kentaro; Kai, Nobuo; Miyamoto, Tadashi; Matsushita, Tomohiro

2017-03-01

Exposure to radiation over many years prompts concerns regarding potential health-related effects, particularly the incidence of cataracts and the development of cancer. The purpose of this study was to examine and compare the exposure of the examiner to radiation during myelography versus radiculography and root block. A total of 114 examinations were performed in our institute in the 6 months. Sixty-two examinations were performed during myelography in the first 3 months (MG group), while 52 were performed during radiculography and root block in the last 3 months (RB group). The examiner wore a torso protector, a neck protector, radiation protection gloves, and radiation protection glasses. Optically stimulated luminescence (OSL) dosimeter badges were placed on both the inside and the outside of each protector. The dosimeters were exchanged every month. Radiation doses (mSv) were measured as the integrated radiation quantity every month from the OSL dosimeters. The effective dose and the equivalent doses of hand, skin, and eyes were investigated. The mean equivalent doses were significantly lower outside the neck, torso, eye protectors, and inside the torso protector in the RB group than in the MG group. Conversely, the mean equivalent dose was significantly lower outside the hand protector in the MG group than in the RB group. The use of a neck protector significantly decreased the effective dose compared to the non-use of a neck protector in the RB group. The present study showed the standard radiation exposure to the examiner during myelography, radiculography, and root block. Receiving full protection including a neck protector and protection gloves is an easy and reliable means to reduce radiation exposure. Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

[Risk of deterministic effects after exposure to low doses of ionizing radiation: retrospective study among health workers in view of a new publication of International Commission on Radiological Protection].

PubMed

Negrone, Mario; Di Lascio, Doriana

2016-01-01

The new recommended equivalent (publication n. 118 of International Commission on Radiological Protection) dose limit for occupational exposure of the lens of the eye is based on prevention of radiogenic cataracts, with the underlying assumption of a nominal threshold which has been adjusted from 2,5 Gy to 0.5 Gy for acute or protracted exposure. The study aim was to determine the prevalence of ocular lens opacity among healthcare workers (radiologic technologists, physicians, physician assistants) with respect to occupational exposures to ionizing radiations. Therefore, we conducted another retrospective study to explore the relationship between occupational exposure to radiation and opacity lens increase. Healthcare data (current occupational dosimetry, occupational history) are used to investigate risk of increase of opacity lens of eye. The sample of this study consisted of 148 health-workers (64 M and 84 W) aged from 28 to 66 years coming from different hospitals of the ASL of Potenza (clinic, hospital and institute with scientific feature). On the basis of the evaluation of the dosimetric history of the workers (global and effective dose) we agreed to ascribe the group of exposed subjects in cat A (equivalent dose > 2 mSV) and the group of non exposed subjects in cat B (workers with annual absorbed level of dose near 0 mSv). The analisys was conducted using SPSS 15.0 (Statistical Package for Social Science). A trend of increased ocular lens opacity was found with increasing number for workers in highest category of exposure (cat. A, Yates' chi-squared test = 13,7 p = 0,0002); variable significantly related to opacity lens results job: nurse (Χ(2)Y = 14,3 p = 0,0002) physician (Χ(2)Y = 2.2 p = 0,1360) and radiologic technologists (Χ(2)Y = 0,1 p = 0,6691). In conclusion our provides evidence that exposure to relatively low doses of ionizing radiation may be harmful to the lens of the eye and may increase a long-term risk of cataract formation; similary necessary to monitor the "equivalent dose" for the lens for the workers in highest category of exposure.

Level of Alkenylbenzenes in Parsley and Dill Based Teas and Associated Risk Assessment Using the Margin of Exposure Approach.

PubMed

Alajlouni, Abdalmajeed M; Al-Malahmeh, Amer J; Isnaeni, Farida Nur; Wesseling, Sebastiaan; Vervoort, Jacques; Rietjens, Ivonne M C M

2016-11-16

Risk assessment of parsley and dill based teas that contain alkenylbenzenes was performed. To this end the estimated daily intake (EDI) of alkenylbenzenes resulting from use of the teas was quantified. Since most teas appeared to contain more than one alkenylbenzene, a combined risk assessment was performed based on equal potency of all alkenylbenzenes or using a so-called toxic equivalency (TEQ) approach through defining toxic equivalency factors (TEFs) for the different alkenylbenzenes. The EDI values resulting from consuming one cup of tea a day were 0.2-10.1 μg/kg bw for the individual alkenylbenzenes, 0.6-13.1 μg/kg bw for the sum of the alkenylbenzenes, and 0.3-10.7 μg safrole equiv/kg bw for the sum of alkenylbenzenes when expressed in safrole equivalents. The margin of exposure (MOE) values obtained were generally <10000, indicating a concern if the teas would be consumed on a daily basis over longer periods of time.

Organochlorine contaminant exposure and effects in pipping black-crowned night-herons in Delaware Bay

USGS Publications Warehouse

Rattner, B.A.; Hoffman, D.J.; Melancon, M.J.; Olsen, Glenn H.; Parsons, K.C.; Schmidt, S.R.

1998-01-01

Pea Patch Island in Delaware Bay is the site of the largest heronry north of Florida. From 1989-93. the population of 9 species of wading birds numbered approximately 12,000 pairs. but has recently declined to 7,000 pairs. Because Delaware Bay is a major shipping channel. and receives anthropogenic releases of toxic substances from agricultural, industrial and municipal point and nonpoint sources, contaminant exposure and effects to the heronry have been an ongoing concern. In 1997, piping black-crowned night-herons (BCNHs) wee collected from separate nests at Pea Patch Island (N=l5), and from a coastal reference site, Middle Island (N=9), in Rehoboth Bay. DE. There was neither evidence of malformations nor hepatic histopathological lesions, and body and liver weights did not differ between sites. Biomarkers of petroleum hydrocarbons, polyhalogenated contaminant and metal exposure (cytochrome P450 induction and oxidative stress responses) did not differ (P>0.05) between sites, however, activities of benzyloxy- and ethoxyresorufin-O-dealkylase were greater in 3 of 15 embryos from Pea Patch Island compared to Middle Island. Concentrations of 21 organochlorine pesticides and metabolites were relatively low at both sites. with p,.p'DDE values well below the threshold associated with eggshell thinning. Although total PCB concentration was modestly elevated (P<0.05) in Pea Patch Island BCNH embryos, levels of axylhydrocarbon-receptor active PCB congeners. dioxins, dibenzofurans and Toxic Equivalents were low and did not differ between sites. Surprisingly, organochlorine contaminant exposure and effects in Delaware Bay BCNHs appear to be considerably less than that observed and recently reported (ETC 16:2315-2322,1997) for herons residing in the Chesapeake Bay.

Elimination Rates of Dioxin Congeners in Former Chlorophenol Workers from Midland, Michigan

PubMed Central

Collins, James J.; Bodner, Kenneth M.; Wilken, Michael; Bodnar, Catherine M.

2012-01-01

Background: Exposure reconstructions and risk assessments for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other dioxins rely on estimates of elimination rates. Limited data are available on elimination rates for congeners other than TCDD. Objectives: We estimated apparent elimination rates using a simple first-order one-compartment model for selected dioxin congeners based on repeated blood sampling in a previously studied population. Methods: Blood samples collected from 56 former chlorophenol workers in 2004–2005 and again in 2010 were analyzed for dioxin congeners. We calculated the apparent elimination half-life in each individual for each dioxin congener and examined factors potentially influencing elimination rates and the impact of estimated ongoing background exposures on rate estimates. Results: Mean concentrations of all dioxin congeners in the sampled participants declined between sampling times. Median apparent half-lives of elimination based on changes in estimated mass in the body were generally consistent with previous estimates and ranged from 6.8 years (1,2,3,7,8,9-hexachlorodibenzo-p-dioxin) to 11.6 years (pentachlorodibenzo-p-dioxin), with a composite half-life of 9.3 years for TCDD toxic equivalents. None of the factors examined, including age, smoking status, body mass index or change in body mass index, initial measured concentration, or chloracne diagnosis, was consistently associated with the estimated elimination rates in this population. Inclusion of plausible estimates of ongoing background exposures decreased apparent half-lives by approximately 10%. Available concentration-dependent toxicokinetic models for TCDD underpredicted observed elimination rates for concentrations < 100 ppt. Conclusions: The estimated elimination rates from this relatively large serial sampling study can inform occupational and environmental exposure and serum evaluations for dioxin compounds. PMID:23063871

Modeling emission rates and exposures from outdoor cooking

NASA Astrophysics Data System (ADS)

Edwards, Rufus; Princevac, Marko; Weltman, Robert; Ghasemian, Masoud; Arora, Narendra K.; Bond, Tami

2017-09-01

Approximately 3 billion individuals rely on solid fuels for cooking globally. For a large portion of these - an estimated 533 million - cooking is outdoors, where emissions from cookstoves pose a health risk to both cooks and other household and village members. Models that estimate emissions rates from stoves in indoor environments that would meet WHO air quality guidelines (AQG), explicitly don't account for outdoor cooking. The objectives of this paper are to link health based exposure guidelines with emissions from outdoor cookstoves, using a Monte Carlo simulation of cooking times from Haryana India coupled with inverse Gaussian dispersion models. Mean emission rates for outdoor cooking that would result in incremental increases in personal exposure equivalent to the WHO AQG during a 24-h period were 126 ± 13 mg/min for cooking while squatting and 99 ± 10 mg/min while standing. Emission rates modeled for outdoor cooking are substantially higher than emission rates for indoor cooking to meet AQG, because the models estimate impact of emissions on personal exposure concentrations rather than microenvironment concentrations, and because the smoke disperses more readily outdoors compared to indoor environments. As a result, many more stoves including the best performing solid-fuel biomass stoves would meet AQG when cooking outdoors, but may also result in substantial localized neighborhood pollution depending on housing density. Inclusion of the neighborhood impact of pollution should be addressed more formally both in guidelines on emissions rates from stoves that would be protective of health, and also in wider health impact evaluation efforts and burden of disease estimates. Emissions guidelines should better represent the different contexts in which stoves are being used, especially because in these contexts the best performing solid fuel stoves have the potential to provide significant benefits.

An analytical model of leakage neutron equivalent dose for passively-scattered proton radiotherapy and validation with measurements.

PubMed

Schneider, Christopher; Newhauser, Wayne; Farah, Jad

2015-05-18

Exposure to stray neutrons increases the risk of second cancer development after proton therapy. Previously reported analytical models of this exposure were difficult to configure and had not been investigated below 100 MeV proton energy. The purposes of this study were to test an analytical model of neutron equivalent dose per therapeutic absorbed dose  at 75 MeV and to improve the model by reducing the number of configuration parameters and making it continuous in proton energy from 100 to 250 MeV. To develop the analytical model, we used previously published H/D values in water from Monte Carlo simulations of a general-purpose beamline for proton energies from 100 to 250 MeV. We also configured and tested the model on in-air neutron equivalent doses measured for a 75 MeV ocular beamline. Predicted H/D values from the analytical model and Monte Carlo agreed well from 100 to 250 MeV (10% average difference). Predicted H/D values from the analytical model also agreed well with measurements at 75 MeV (15% average difference). The results indicate that analytical models can give fast, reliable calculations of neutron exposure after proton therapy. This ability is absent in treatment planning systems but vital to second cancer risk estimation.

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

Matsui, Yusuke, E-mail: wckyh140@yahoo.co.jp; Hiraki, Takao, E-mail: takaoh@tc4.so-net.ne.jp; Gobara, Hideo, E-mail: gobara@cc.okayama-u.ac.jp

IntroductionComputed tomography (CT) fluoroscopy-guided renal cryoablation and lung radiofrequency ablation (RFA) have received increasing attention as promising cancer therapies. Although radiation exposure of interventional radiologists during these procedures is an important concern, data on operator exposure are lacking.Materials and MethodsRadiation dose to interventional radiologists during CT fluoroscopy-guided renal cryoablation (n = 20) and lung RFA (n = 20) was measured prospectively in a clinical setting. Effective dose to the operator was calculated from the 1-cm dose equivalent measured on the neck outside the lead apron, and on the left chest inside the lead apron, using electronic dosimeters. Equivalent dose to the operator’s finger skinmore » was measured using thermoluminescent dosimeter rings.ResultsThe mean (median) effective dose to the operator per procedure was 6.05 (4.52) μSv during renal cryoablation and 0.74 (0.55) μSv during lung RFA. The mean (median) equivalent dose to the operator’s finger skin per procedure was 2.1 (2.1) mSv during renal cryoablation, and 0.3 (0.3) mSv during lung RFA.ConclusionRadiation dose to interventional radiologists during renal cryoablation and lung RFA were at an acceptable level, and in line with recommended dose limits for occupational radiation exposure.« less

Calibration factors for the SNOOPY NP-100 neutron dosimeter

NASA Astrophysics Data System (ADS)

Moscu, D. F.; McNeill, F. E.; Chase, J.

2007-10-01

Within CANDU nuclear power facilities, only a small fraction of workers are exposed to neutron radiation. For these individuals, roughly 4.5% of the total radiation equivalent dose is the result of exposure to neutrons. When this figure is considered across all workers receiving external exposure of any kind, only 0.25% of the total radiation equivalent dose is the result of exposure to neutrons. At many facilities, the NP-100 neutron dosimeter, manufactured by Canberra Industries Incorporated, is employed in both direct and indirect dosimetry methods. Also known as "SNOOPY", these detectors undergo calibration, which results in a calibration factor relating the neutron count rate to the ambient dose equivalent rate, using a standard Am-Be neutron source. Using measurements presented in a technical note, readings from the dosimeter for six different neutron fields in six source-detector orientations were used, to determine a calibration factor for each of these sources. The calibration factor depends on the neutron energy spectrum and the radiation weighting factor to link neutron fluence to equivalent dose. Although the neutron energy spectra measured in the CANDU workplace are quite different than that of the Am-Be calibration source, the calibration factor remains constant - within acceptable limits - regardless of the neutron source used in the calibration; for the specified calibration orientation and current radiation weighting factors. However, changing the value of the radiation weighting factors would result in changes to the calibration factor. In the event of changes to the radiation weighting factors, it will be necessary to assess whether a change to the calibration process or resulting calibration factor is warranted.

Skeletal dosimetry for external exposure to photons based on µCT images of spongiosa from different bone sites

NASA Astrophysics Data System (ADS)

Kramer, R.; Khoury, H. J.; Vieira, J. W.; Kawrakow, I.

2007-11-01

Micro computed tomography (µCT) images of human spongiosa have recently been used for skeletal dosimetry with respect to external exposure to photon radiation. In this previous investigation, the calculation of equivalent dose to the red bone marrow (RBM) and to the bone surface cells (BSC) was based on five different clusters of micro matrices derived from µCT images of vertebrae, and the BSC equivalent dose for 10 µm thickness of the BSC layer was determined using an extrapolation method. The purpose of this study is to extend the earlier investigation by using µCT images from eight different bone sites and by introducing an algorithm for the direct calculation of the BSC equivalent dose with sub-micro voxel resolution. The results show that for given trabecular bone volume fractions (TBVFs) the whole-body RBM equivalent dose does not depend on bone site-specific properties or imaging parameters. However, this study demonstrates that apart from the TBVF and the BSC layer thickness, the BSC equivalent dose additionally depends on a so-called trabecular bone structure (TBS) effect, i.e. that the contribution of photo-electrons released in trabecular bone to the BSC equivalent dose also depends on the bone site-specific structure of the trabeculae. For a given bone site, the TBS effect is also a function of the thickness of the BSC layer, and it could be shown that this effect would disappear almost completely, should the BSC layer thickness be raised from 10 to 50 µm, according to new radiobiological findings.

76 FR 787 - Notice of Availability of the Recommended Toxicity Equivalence Factors (TEFs) for Human Health...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-06

... manufacturing, combustion, and metal processing. There is global contamination of air, soil and water with trace... food chain, and accumulate in the tissues of animals. Human exposures to these compounds occur primarily through eating contaminated foods. The health effects from exposures to dioxins and DLCs have been...

Counteracting tobacco motor sports sponsorship as a promotional tool: is the tobacco settlement enough?

PubMed

Siegel, M

2001-07-01

This study sought to quantify television advertising exposure achieved by tobacco companies through sponsorship of motor sports events and to evaluate the likely effect of the Master Settlement Agreement on this advertising. Data from Sponsors Report, which quantifies the exposure that sponsors of selected televised sporting events receive during broadcasts of those events, were compiled for all motor sports events covered by the service for the period 1997 through 1999. From 1997 through 1999, tobacco companies achieved 169 hours of television advertising exposure and $410.5 million of advertising value for their products by sponsoring motor sports events. If tobacco companies comply with the Master Settlement Agreement and maintain their advertising at 1999 levels, they will still be able to achieve more than 25 hours of television exposure and an equivalent television advertising value of $99.1 million per year. Despite a federal ban on tobacco advertising on television, tobacco companies achieve the equivalent of more than $150 million in television advertising per year through their sponsorship of motor sports events. The Master Settlement Agreement likely will do little to address this problem.

Modelling of aircrew radiation exposure from galactic cosmic rays and solar particle events.

PubMed

Takada, M; Lewis, B J; Boudreau, M; Al Anid, H; Bennett, L G I

2007-01-01

Correlations have been developed for implementation into the semi-empirical Predictive Code for Aircrew Radiation Exposure (PCAIRE) to account for effects of extremum conditions of solar modulation and low altitude based on transport code calculations. An improved solar modulation model, as proposed by NASA, has been further adopted to interpolate between the bounding correlations for solar modulation. The conversion ratio of effective dose to ambient dose equivalent, as applied to the PCAIRE calculation (based on measurements) for the legal regulation of aircrew exposure, was re-evaluated in this work to take into consideration new ICRP-92 radiation-weighting factors and different possible irradiation geometries of the source cosmic-radiation field. A computational analysis with Monte Carlo N-Particle eXtended Code was further used to estimate additional aircrew exposure that may result from sporadic solar energetic particle events considering real-time monitoring by the Geosynchronous Operational Environmental Satellite. These predictions were compared with the ambient dose equivalent rates measured on-board an aircraft and to count rate data observed at various ground-level neutron monitors.

Reliability of the pair-defect-sum approximation for the strength of valence-bond orbitals

PubMed Central

Pauling, Linus; Herman, Zelek S.; Kamb, Barclay J.

1982-01-01

The pair-defect-sum approximation to the bond strength of a hybrid orbital (angular wave functions only) is compared to the rigorous value as a function of bond angle for seven types of bonding situations, with between three and eight bond directions equivalent by geometrical symmetry operations and with only one independent bond angle. The approximation is seen to be an excellent one in all cases, and the results provide a rationale for the application of this approximation to a variety of problems. PMID:16593167

NTP toxicology and carcinogenesis studies of chromium picolinate monohydrate (CAS No. 27882-76-4) in F344/N rats and B6C3F1 mice (feed studies).

PubMed

2010-06-01

Chromium picolinate monohydrate is the commercially available form of chromium picolinate. Chromium picolinate is one of a number of compounds that contain chromium in the trivalent state (Cr III), which is the predominant form of chromium in nature. Humans ingest Cr III in food and dietary supplements. The major uses of Cr III in the chemical and manufacturing industries include production of chromium pigments and leather tanning. Chromium picolinate was nominated by the National Cancer Institute and a private individual for testing based on the potential for widespread consumer exposure from use as a dietary supplement. Male and female F344/N rats and B6C3F1 mice were exposed to chromium picolinate monohydrate (95% to 96% pure) in feed for 3 months or 2 years. Genetic toxicology studies with chromium picolinate monohydrate were conducted in Salmonella typhimurium and mouse peripheral blood erythrocytes. Genetic toxicology studies with chromium picolinate were conducted in S. typhimurium and rat bone marrow cells. 3-MONTH STUDY IN RATS: Groups of 10 male and 10 female rats were fed diets containing 0, 80, 240, 2,000, 10,000, or 50,000 ppm chromium picolinate monohydrate (equivalent to average daily doses of approximately 7, 20, 160, 800, and 4,240 mg chromium picolinate monohydrate/kg body weight to males and 6, 20, 160, 780, and 4,250 mg/kg to females) for 14 weeks. All rats survived to the end of the study. Mean body weights and feed consumption of all exposed groups of males and females were similar to those of the control groups throughout the study. No exposure-related lesions occurred in males or females. 3-MONTH STUDY IN MICE: Groups of 10 male and 10 female mice were fed diets containing 0, 80, 240, 2,000, 10,000, or 50,000 ppm chromium picolinate monohydrate (equivalent to average daily doses of approximately 17, 50, 450, 2,300, and 11,900 mg chromium picolinate monohydrate/kg body weight to males and 14, 40, 370, 1,775, and 9,140 mg/kg to females) for 14 weeks. All mice survived to the end of the study. Mean body weights and feed consumption of all exposed groups were similar to those of the control groups throughout the study. No exposure-related lesions occurred in male or female mice. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were fed diets containing 0, 2,000, 10,000, or 50,000 ppm chromium picolinate monohydrate (equivalent to average daily doses of approximately 90, 460, and 2,400 mg/kg to males and 100, 510, and 2,630 mg/kg to females) for 105 weeks. Survival of all exposed groups of males and females was similar to that of the control groups. Mean body weights and feed consumption of exposed groups of males and females were generally similar to those of the controls throughout the study. The incidence of preputial gland adenoma was significantly increased in males exposed to 10,000 ppm and exceeded the historical control ranges. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were fed diets containing 0, 2,000, 10,000, or 50,000 ppm chromium picolinate monohydrate (equivalent to average daily doses of approximately 250, 1,200, and 6,565 mg/kg to males and 240, 1,200, and 6,100 mg/kg to females) for 105 weeks. Survival of all exposed groups of males and females was similar to that of the control groups. Mean body weights of exposed groups of males were generally similar to those of the controls throughout the study; mean body weights of 50,000 ppm females was 10% less than the control group at 1 year. Feed consumption by exposed groups of males and females was similar to that by the controls throughout the study. No neoplasms or nonneoplastic lesions were attributed to exposure to chromium picolinate monohydrate. In the standard screening assays conducted by the NTP, chromium picolinate monohydrate showed no clear evidence of genotoxicity. It was not mutagenic in Salmonella typhimurium strains TA98 or TA100 or Escherichia coli strain WP2 uvrA/pKM101 when tested with or without exogenous metabolic activation (S9). No increase in the frequency of micronucleated normochromatic erythrocytes was observed in male B6C3F1 mice administered chromium picolinate monohydrate in feed for 3 months. A small increase in micronucleated normochromatic erythrocytes was seen in female mice at the highest exposure concentration tested, and the results in female mice were considered equivocal. Additional genotoxicity testing was conducted with chromium picolinate (not the monohydrate form of the compound), and results were also negative. No induction of gene mutations was observed in two independent studies conducted in several strains of S. typhimurium with and without S9. No induction of micronucleated polychromatic erythrocytes was observed in bone marrow of male F344/N rats treated with chromium picolinate by oral gavage three times at 24-hour intervals. Under the conditions of these 2-year feed studies there was equivocal evidence of carcinogenic activity* of chromium picolinate monohydrate in male F344/N rats based on an increase in the incidence of preputial gland adenoma. There was no evidence of carcinogenic activity of chromium picolinate monohydrate in female F344/N rats or in male or female B6C3F1 mice.

Comparison of adult and child radiation equivalent doses from 2 dental cone-beam computed tomography units.

PubMed

Al Najjar, Anas; Colosi, Dan; Dauer, Lawrence T; Prins, Robert; Patchell, Gayle; Branets, Iryna; Goren, Arthur D; Faber, Richard D

2013-06-01

With the advent of cone-beam computed tomography (CBCT) scans, there has been a transition toward these scans' replacing traditional radiographs for orthodontic diagnosis and treatment planning. Children represent a significant proportion of orthodontic patients. Similar CBCT exposure settings are predicted to result in higher equivalent doses to the head and neck organs in children than in adults. The purpose of this study was to measure the difference in equivalent organ doses from different scanners under similar settings in children compared with adults. Two phantom heads were used, representing a 33-year-old woman and a 5-year-old boy. Optically stimulated dosimeters were placed at 8 key head and neck organs, and equivalent doses to these organs were calculated after scanning. The manufacturers' predefined exposure settings were used. One scanner had a pediatric preset option; the other did not. Scanning the child's phantom head with the adult settings resulted in significantly higher equivalent radiation doses to children compared with adults, ranging from a 117% average ratio of equivalent dose to 341%. Readings at the cervical spine level were decreased significantly, down to 30% of the adult equivalent dose. When the pediatric preset was used for the scans, there was a decrease in the ratio of equivalent dose to the child mandible and thyroid. CBCT scans with adult settings on both phantom heads resulted in higher radiation doses to the head and neck organs in the child compared with the adult. In practice, this might result in excessive radiation to children scanned with default adult settings. Collimation should be used when possible to reduce the radiation dose to the patient. While CBCT scans offer a valuable tool, use of CBCT scans should be justified on a specific case-by-case basis. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Evidence for equivalence of diffusion processes of passive scalar and magnetic fields in anisotropic Navier-Stokes turbulence.

PubMed

Jurčišinová, E; Jurčišin, M

2017-05-01

The influence of the uniaxial small-scale anisotropy on the kinematic magnetohydrodynamic turbulence is investigated by using the field theoretic renormalization group technique in the one-loop approximation of a perturbation theory. The infrared stable fixed point of the renormalization group equations, which drives the scaling properties of the model in the inertial range, is investigated as the function of the anisotropy parameters and it is shown that, at least at the one-loop level of approximation, the diffusion processes of the weak passive magnetic field in the anisotropically driven kinematic magnetohydrodynamic turbulence are completely equivalent to the corresponding diffusion processes of passively advected scalar fields in the anisotropic Navier-Stokes turbulent environments.

Cumulative effects from repeated exposures to ultraviolet radiation

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

Kaidbey, K.H.; Kligman, A.M.

Repeated exposures to subliminal doses of UVR, given at 24-hr intervals, resulted in a lowering of the erythema threshold dose. At erythemogenically equivalent doses, UV-A was the most effective and UV-C the least. A similar and more pronounced effect was observed following repeated exposures to subthreshold doses of UV-A and topically applied 8-methoxypsoralen. These findings provide quantitative evidence for the cumulative nature of acute UVR damage in human skin.

Standing adult human phantoms based on 10th, 50th and 90th mass and height percentiles of male and female Caucasian populations

NASA Astrophysics Data System (ADS)

Cassola, V. F.; Milian, F. M.; Kramer, R.; de Oliveira Lira, C. A. B.; Khoury, H. J.

2011-07-01

Computational anthropomorphic human phantoms are useful tools developed for the calculation of absorbed or equivalent dose to radiosensitive organs and tissues of the human body. The problem is, however, that, strictly speaking, the results can be applied only to a person who has the same anatomy as the phantom, while for a person with different body mass and/or standing height the data could be wrong. In order to improve this situation for many areas in radiological protection, this study developed 18 anthropometric standing adult human phantoms, nine models per gender, as a function of the 10th, 50th and 90th mass and height percentiles of Caucasian populations. The anthropometric target parameters for body mass, standing height and other body measures were extracted from PeopleSize, a well-known software package used in the area of ergonomics. The phantoms were developed based on the assumption of a constant body-mass index for a given mass percentile and for different heights. For a given height, increase or decrease of body mass was considered to reflect mainly the change of subcutaneous adipose tissue mass, i.e. that organ masses were not changed. Organ mass scaling as a function of height was based on information extracted from autopsy data. The methods used here were compared with those used in other studies, anatomically as well as dosimetrically. For external exposure, the results show that equivalent dose decreases with increasing body mass for organs and tissues located below the subcutaneous adipose tissue layer, such as liver, colon, stomach, etc, while for organs located at the surface, such as breasts, testes and skin, the equivalent dose increases or remains constant with increasing body mass due to weak attenuation and more scatter radiation caused by the increasing adipose tissue mass. Changes of standing height have little influence on the equivalent dose to organs and tissues from external exposure. Specific absorbed fractions (SAFs) have also been calculated with the 18 anthropometric phantoms. The results show that SAFs decrease with increasing height and increase with increasing body mass. The calculated data suggest that changes of the body mass may have a significant effect on equivalent doses, primarily for external exposure to organs and tissue located below the adipose tissue layer, while for superficial organs, for changes of height and for internal exposures the effects on equivalent dose are small to moderate.

An approach for including the stiffness and damping of elastohydrodynamic point contacts in deep groove ball bearing equilibrium models

NASA Astrophysics Data System (ADS)

Nonato, Fábio; Cavalca, Katia L.

2014-12-01

This work presents a methodology for including the Elastohydrodynamic (EHD) film effects to a lateral vibration model of a deep groove ball bearing by using a novel approximation for the EHD contacts by a set of equivalent nonlinear spring and viscous damper. The fitting of the equivalent contact model used the results of a transient multi-level finite difference EHD algorithm to adjust the dynamic parameters. The comparison between the approximated model and the finite difference simulated results showed a suitable representation of the stationary and dynamic contact behaviors. The linear damping hypothesis could be shown as a rough representation of the actual hysteretic behavior of the EHD contact. Nevertheless, the overall accuracy of the model was not impaired by the use of such approximation. Further on, the inclusion of the equivalent EHD contact model is equated for both the restoring and the dissipative components of the bearing's lateral dynamics. The derived model was used to investigate the effects of the rolling element bearing lubrication on the vibration response of a rotor's lumped parameter model. The fluid film stiffening effect, previously only observable by experimentation, could be quantified using the proposed model, as well as the portion of the bearing damping provided by the EHD fluid film. Results from a laboratory rotor-bearing test rig were used to indirectly validate the proposed contact approximation. A finite element model of the rotor accounting for the lubricated bearing formulation adequately portrayed the frequency content of the bearing orbits observed on the test rig.

Application of high-resolution time-of-flight chemical ionization mass spectrometry measurements to estimate volatility distributions of α-pinene and naphthalene oxidation products

DOE PAGES

Chhabra, P. S.; Lambe, A. T.; Canagaratna, M. R.; ...

2015-01-05

Recent developments in high-resolution time-of-flight chemical ionization mass spectrometry (HR-ToF-CIMS) have made it possible to directly detect atmospheric organic compounds in real time with high sensitivity and with little or no fragmentation, including low-volatility, highly oxygenated organic vapors that are precursors to secondary organic aerosol formation. Here, using ions identified by high-resolution spectra from an HR-ToF-CIMS with acetate reagent ion chemistry, we develop an algorithm to estimate the vapor pressures of measured organic acids. The algorithm uses identified ion formulas and calculated double bond equivalencies, information unavailable in quadrupole CIMS technology, as constraints for the number of possible oxygen-containing functionalmore » groups. The algorithm is tested with acetate chemical ionization mass spectrometry (acetate-CIMS) spectra of O 3 and OH oxidation products of α-pinene and naphthalene formed in a flow reactor with integrated OH exposures ranged from 1.2 × 10 11 to 9.7 × 10 11 molec s cm −3, corresponding to approximately 1.0 to 7.5 days of equivalent atmospheric oxidation. Measured gas-phase organic acids are similar to those previously observed in environmental chamber studies. For both precursors, we find that acetate-CIMS spectra capture both functionalization (oxygen addition) and fragmentation (carbon loss) as a function of OH exposure. The level of fragmentation is observed to increase with increased oxidation. The predicted condensed-phase secondary organic aerosol (SOA) average acid yields and O/C and H/C ratios agree within uncertainties with previous chamber and flow reactor measurements and ambient CIMS results. Furthermore, while acetate reagent ion chemistry is used to selectively measure organic acids, in principle this method can be applied to additional reagent ion chemistries depending on the application.« less

Protection of the public in situations of prolonged radiation exposure. The application of the Commission's system of radiological protection to controllable radiation exposure due to natural sources and long-lived radioactive residues.

PubMed

1999-01-01

This report provides guidance on the application of the ICRP system of radiological protection to prolonged exposure situations affecting members of the public. It addresses the general application of the Commission's system to the control of prolonged exposures resulting from practices and to the undertaking of interventions in prolonged exposure situations. Additionally, it provides recommendations on generic reference levels for such interventions. The report also considers some specific situations and discusses a number of issues that have been of concern, namely: natural radiation sources that may give rise to high doses; the restoration and rehabilitation of sites where human activities involving radioactive substances have been carried out; the return to 'normality' following an accident that has released radioactive substances to the environment; and the global marketing of commodities for public consumption that contain radioactive substances. Annexes provide some examples of prolonged exposure situations and discuss the radiological protection quantities, radiation-induced health effects and aspects of the Commission's system of radiological protection relevant to prolonged exposure. Quantitative recommendations for prolonged exposures are provided in the report. They must be interpreted with extreme caution; Chapters 4 and 5 stress the upper bound nature of the following values: Generic reference levels for intervention, in terms of existing total annual doses, are given as < approximately 100 mSv, above which intervention is almost always justifiable (situations for which the annual dose threshold for deterministic effects in relevant organs is exceeded will almost always require intervention), and < approximately 10 mSv, below which intervention is not likely to be justifiable (and above which it may be necessary). Intervention exemption levels for commodities, especially building materials, are expressed as an additional annual dose of approximately 1 mSv. The dose limit for exposures of the public from practices is expressed as aggregated (prolonged and transitory) additional annual doses from all relevant practices of 1 mSv. Dose constraints for sources within practices are expressed as an additional annual dose lower than 1 mSv (e.g. of approximately 0.3 mSv), which could be approximately 0.1 mSv for the prolonged exposure component. An exemption level for practices is expressed as an additional annual dose of approximately 0.01 mSv.

Flame quenching by a variable-width rectangular-slot burner as a function of pressure for various propane-oxygen-nitrogen mixtures

NASA Technical Reports Server (NTRS)

Berlad, Abraham L

1954-01-01

Flame quenching by a variable-width rectangular-slot burner as a function of pressure for various propane-oxygen-nitrogen mixtures was investigated. It was found that for cold gas temperatures of 27 degrees C, pressures of 0.1 ro 1.0 atmosphere, and volumetric oxygen reactions of the oxidant of 0.17, 0.21, 0.30, 0.50, and 0.70, the relation between pressure p and quenching distance d is approximately given by d (unity) p (superscript -r) with r = 1, for equivalence ratios approximately equal to one. The quenching equation of Simon and Belles was tested. For equivalence ratios less than or equal to unity, this equation may by used, together with one empirical constant, to predict the observed quenching distance within 4.2 percent. The equation in it's present form does not appear to be suitable for values of the equivalence ratio greater than unity. A quantitative theoretical investigation has also been made of the error implicit in the assumption that flame quenching by plane parallel plates of infinite extent is equivalent to that of a rectangular burner. A curve is presented which relates the magnitude of this error to the length-to-width ratio of the rectangular burner.

Light field geometry of a Standard Plenoptic Camera.

PubMed

Hahne, Christopher; Aggoun, Amar; Haxha, Shyqyri; Velisavljevic, Vladan; Fernández, Juan Carlos Jácome

2014-11-03

The Standard Plenoptic Camera (SPC) is an innovation in photography, allowing for acquiring two-dimensional images focused at different depths, from a single exposure. Contrary to conventional cameras, the SPC consists of a micro lens array and a main lens projecting virtual lenses into object space. For the first time, the present research provides an approach to estimate the distance and depth of refocused images extracted from captures obtained by an SPC. Furthermore, estimates for the position and baseline of virtual lenses which correspond to an equivalent camera array are derived. On the basis of paraxial approximation, a ray tracing model employing linear equations has been developed and implemented using Matlab. The optics simulation tool Zemax is utilized for validation purposes. By designing a realistic SPC, experiments demonstrate that a predicted image refocusing distance at 3.5 m deviates by less than 11% from the simulation in Zemax, whereas baseline estimations indicate no significant difference. Applying the proposed methodology will enable an alternative to the traditional depth map acquisition by disparity analysis.

Total-dose radiation effects data for semiconductor devices. 1985 Supplement. Volume 2, part B

NASA Technical Reports Server (NTRS)

Martin, K. E.; Gauthier, M. K.; Coss, J. R.; Dantas, A. R. V.; Price, W. E.

1986-01-01

Steady-state, total-dose radiation test data are provided in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. The document is in two volumes: Volume 1 provides data on diodes, bipolar transistors, field effect transistors, and miscellaneous semiconductor types, and Volume 2 (Parts A and B) provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done steady-state 2.5-MeV electron beam. However, some radiation exposures were made with a Cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose. All data were generated in support of NASA space programs by the JPL Radiation Effects and Testing Group (514).

Equivalent Discrete-Time Channel Modeling for Molecular Communication With Emphasize on an Absorbing Receiver.

PubMed

Damrath, Martin; Korte, Sebastian; Hoeher, Peter Adam

2017-01-01

This paper introduces the equivalent discrete-time channel model (EDTCM) to the area of diffusion-based molecular communication (DBMC). Emphasis is on an absorbing receiver, which is based on the so-called first passage time concept. In the wireless communications community the EDTCM is well known. Therefore, it is anticipated that the EDTCM improves the accessibility of DBMC and supports the adaptation of classical wireless communication algorithms to the area of DBMC. Furthermore, the EDTCM has the capability to provide a remarkable reduction of computational complexity compared to random walk based DBMC simulators. Besides the exact EDTCM, three approximations thereof based on binomial, Gaussian, and Poisson approximation are proposed and analyzed in order to further reduce computational complexity. In addition, the Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm is adapted to all four channel models. Numerical results show the performance of the exact EDTCM, illustrate the performance of the adapted BCJR algorithm, and demonstrate the accuracy of the approximations.

Principles of quasi-equivalence and Euclidean geometry govern the assembly of cubic and dodecahedral cores of pyruvate dehydrogenase complexes.

PubMed

Izard, T; Aevarsson, A; Allen, M D; Westphal, A H; Perham, R N; de Kok, A; Hol, W G

1999-02-16

The pyruvate dehydrogenase multienzyme complex (Mr of 5-10 million) is assembled around a structural core formed of multiple copies of dihydrolipoyl acetyltransferase (E2p), which exhibits the shape of either a cube or a dodecahedron, depending on the source. The crystal structures of the 60-meric dihydrolipoyl acyltransferase cores of Bacillus stearothermophilus and Enterococcus faecalis pyruvate dehydrogenase complexes were determined and revealed a remarkably hollow dodecahedron with an outer diameter of approximately 237 A, 12 large openings of approximately 52 A diameter across the fivefold axes, and an inner cavity with a diameter of approximately 118 A. Comparison of cubic and dodecahedral E2p assemblies shows that combining the principles of quasi-equivalence formulated by Caspar and Klug [Caspar, D. L. & Klug, A. (1962) Cold Spring Harbor Symp. Quant. Biol. 27, 1-4] with strict Euclidean geometric considerations results in predictions of the major features of the E2p dodecahedron matching the observed features almost exactly.

Diet composition modifies the toxicity of repeated soman exposure in rats.

PubMed

Langston, Jeffrey L; Myers, Todd M

2011-12-01

It was previously demonstrated that diet potently modulates the toxic effects of an acute lethal dose of the nerve agent soman. The current investigation was undertaken to examine the influence of diet on the cumulative toxicity of repeated soman administration. Rats were fed one of four distinct diets (standard, choline-enriched, glucose-enriched, or ketogenic) for four weeks prior to and throughout a repeated soman dosing and recovery regimen. Each diet group included animals exposed to an equivalent volume of saline that served as negative controls. In exposure Week 1, animals received three consecutive daily doses of 0.4 LD(50) soman. In exposure Week 2, animals received four consecutive daily doses of 0.5 LD(50) soman. In exposure Week 3, animals received five consecutive daily doses of 0.5 LD(50) soman. Week 4 constituted a post-exposure recovery evaluation. Throughout the experiment, behavioral function was assessed by a discriminated avoidance test that required intact sensory and motor function. Survival and body weight changes were recorded daily. Differences in toxicity as a function of diet composition became apparent during the first week. Specifically, rats fed the glucose-enriched diet showed pronounced intoxication during Week 1, resulting in imperfect survival, weight loss, and deteriorated avoidance performance relative to all other groups. All rats fed the glucose-enriched diet died by the end of exposure Week 2. In contrast, only 10% of animals fed the standard diet died by the end of Week 2. Also in Week 2, weight loss and disrupted avoidance performance were apparent for all groups except for those fed the ketogenic diet. This differential effect of diet composition became even more striking in Week 3 when survival in the standard and choline diet groups approximated 50%, whereas survival equaled 90% in the ketogenic diet group. Avoidance performance and weight loss measures corroborated the differential toxicity observed across diet groups. Upon cessation of soman exposure during the final week, recovery of weight and avoidance performance in survivors was comparable across diet groups. These results systematically replicate previous findings demonstrating that diet composition exacerbates or attenuates toxicity in rodents exposed acutely to organophosphorus compounds. Published by Elsevier B.V.

Lethal and sub-lethal chronic effects of the herbicide diuron on seagrass.

PubMed

Negri, Andrew P; Flores, Florita; Mercurio, Phil; Mueller, Jochen F; Collier, Catherine J

2015-08-01

Photosystem II herbicides from agricultural sources have been detected throughout nearshore tropical habitats including seagrass meadows. While PSII herbicides have been shown to inhibit growth in microalgae at low concentrations, the potential impacts of chronic low concentration exposures to seagrass health and growth have not been investigated. Here we exposed two tropical seagrass species Halodule uninervis and Zostera muelleri to elevated diuron concentrations (from 0.3 to 7.2μgl(-1)) over a 79-day period followed by a 2-week recovery period in uncontaminated seawater. PAM fluorometry demonstrated rapid effect of diuron on photosystem II (PSII) in both seagrass species at 0.3μgl(-1). This effect included significant inhibition of photosynthetic efficiency (ΔF/Fm') and inactivation of PSII (Fv/Fm) over the 11 week exposure period. Significant mortality and reductions in growth was only observed at the highest exposure concentration of 7.2μgl(-1) diuron. However, biochemical indicators demonstrated that the health of seagrass after this prolonged exposure was significantly compromised at lower concentrations. For example, the drop in C:N ratios (0.6μgl(-1)) and reduced δ(13)C (1.7μgl(-1)) in seagrass leaves indicated reduced C-assimilation from photosynthesis. Critically, the energetic reserves of the plants (as measured by starch content in the root-rhizome complex) were approximately halved following diuron exposure at and above 1.7μgl(-1). During the 2-week recovery period, the photosynthetic capacity of the seagrass improved with only plants from the highest diuron treatment still exhibiting chronic damage to PSII. This study shows that, although seagrass may survive prolonged herbicide exposures, concentrations ≥0.6μgl(-1) diuron equivalents cause measureable impacts on energetic status that may leave the plants vulnerable to other simultaneous stressors. For example, tropical seagrasses have been heavily impacted by reduced light from coastal flood plumes and the effects on plant energetics from light limitation and diuron exposure (highest in flood plumes) are very similar, potentially leading to cumulative negative effects. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Expression of proliferative and inflammatory markers in a full-thickness human skin equivalent following exposure to the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide

PubMed Central

Black, Adrienne T.; Hayden, Patrick J.; Casillas, Robert P.; Heck, Diane E.; Gerecke, Donald R.; Sinko, Patrick J.; Laskin, Debra L.; Laskin, Jeffrey D.

2010-01-01

Sulfur mustard is a potent vesicant that induces inflammation, edema and blistering following dermal exposure. To assess molecular mechanisms mediating these responses, we analyzed the effects of the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide, on EpiDerm-FT™, a commercially available full-thickness human skin equivalent. CEES (100–1000 μM) caused a concentration-dependent increase in pyknotic nuclei and vacuolization in basal keratinocytes; at high concentrations (300–1000 μM), CEES also disrupted keratin filament architecture in the stratum corneum. This was associated with time-dependent increases in expression of proliferating cell nuclear antigen, a marker of cell proliferation, and poly(ADP-ribose) polymerase (PARP) and phosphorylated histone H2AX, markers of DNA damage. Concentration- and time-dependent increases in mRNA and protein expression of eicosanoid biosynthetic enzymes including COX-2, 5-lipoxygenase, microsomal PGE2 synthases, leukotriene (LT) A4 hydrolase and LTC4 synthase were observed in CEES-treated skin equivalents, as well as in antioxidant enzymes, glutathione S-transferases A1–2 (GSTA1–2), GSTA3 and GSTA4. These data demonstrate that CEES induces rapid cellular damage, cytotoxicity and inflammation in full-thickness skin equivalents. These effects are similar to human responses to vesicants in vivo and suggest that the full thickness skin equivalent is a useful in vitro model to characterize the biological effects of mustards and to develop potential therapeutics. PMID:20840853

Simulated Response of a Tissue-equivalent Proportional Counter on the Surface of Mars.

PubMed

Northum, Jeremy D; Guetersloh, Stephen B; Braby, Leslie A; Ford, John R

2015-10-01

Uncertainties persist regarding the assessment of the carcinogenic risk associated with galactic cosmic ray (GCR) exposure during a mission to Mars. The GCR spectrum peaks in the range of 300(-1) MeV n to 700 MeV n(-1) and is comprised of elemental ions from H to Ni. While Fe ions represent only 0.03% of the GCR spectrum in terms of particle abundance, they are responsible for nearly 30% of the dose equivalent in free space. Because of this, radiation biology studies focusing on understanding the biological effects of GCR exposure generally use Fe ions. Acting as a thin shield, the Martian atmosphere alters the GCR spectrum in a manner that significantly reduces the importance of Fe ions. Additionally, albedo particles emanating from the regolith complicate the radiation environment. The present study uses the Monte Carlo code FLUKA to simulate the response of a tissue-equivalent proportional counter on the surface of Mars to produce dosimetry quantities and microdosimetry distributions. The dose equivalent rate on the surface of Mars was found to be 0.18 Sv y(-1) with an average quality factor of 2.9 and a dose mean lineal energy of 18.4 keV μm(-1). Additionally, albedo neutrons were found to account for 25% of the dose equivalent. It is anticipated that these data will provide relevant starting points for use in future risk assessment and mission planning studies.

Expression of proliferative and inflammatory markers in a full-thickness human skin equivalent following exposure to the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide.

PubMed

Black, Adrienne T; Hayden, Patrick J; Casillas, Robert P; Heck, Diane E; Gerecke, Donald R; Sinko, Patrick J; Laskin, Debra L; Laskin, Jeffrey D

2010-12-01

Sulfur mustard is a potent vesicant that induces inflammation, edema and blistering following dermal exposure. To assess molecular mechanisms mediating these responses, we analyzed the effects of the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide, on EpiDerm-FT™, a commercially available full-thickness human skin equivalent. CEES (100-1000 μM) caused a concentration-dependent increase in pyknotic nuclei and vacuolization in basal keratinocytes; at high concentrations (300-1000 μM), CEES also disrupted keratin filament architecture in the stratum corneum. This was associated with time-dependent increases in expression of proliferating cell nuclear antigen, a marker of cell proliferation, and poly(ADP-ribose) polymerase (PARP) and phosphorylated histone H2AX, markers of DNA damage. Concentration- and time-dependent increases in mRNA and protein expression of eicosanoid biosynthetic enzymes including COX-2, 5-lipoxygenase, microsomal PGE₂ synthases, leukotriene (LT) A₄ hydrolase and LTC₄ synthase were observed in CEES-treated skin equivalents, as well as in antioxidant enzymes, glutathione S-transferases A1-2 (GSTA1-2), GSTA3 and GSTA4. These data demonstrate that CEES induces rapid cellular damage, cytotoxicity and inflammation in full-thickness skin equivalents. These effects are similar to human responses to vesicants in vivo and suggest that the full thickness skin equivalent is a useful in vitro model to characterize the biological effects of mustards and to develop potential therapeutics. Copyright © 2010 Elsevier Inc. All rights reserved.

Benefits of Stimulus Exposure: Developmental Learning Independent of Task Performance

PubMed Central

Green, David B.; Ohlemacher, Jocelyn; Rosen, Merri J.

2016-01-01

Perceptual learning (training-induced performance improvement) can be elicited by task-irrelevant stimulus exposure in humans. In contrast, task-irrelevant stimulus exposure in animals typically disrupts perception in juveniles while causing little to no effect in adults. This may be due to the extent of exposure, which is brief in humans while chronic in animals. Here we assessed the effects of short bouts of passive stimulus exposure on learning during development in gerbils, compared with non-passive stimulus exposure (i.e., during testing). We used prepulse inhibition of the acoustic startle response, a method that can be applied at any age, to measure gap detection thresholds across four age groups, spanning development. First, we showed that both gap detection thresholds and gap detection learning across sessions displayed a long developmental trajectory, improving throughout the juvenile period. Additionally, we demonstrated larger within- and across-animal performance variability in younger animals. These results are generally consistent with results in humans, where there are extended developmental trajectories for both the perception of temporally-varying signals, and the effects of perceptual training, as well as increased variability and poorer performance consistency in children. We then chose an age (mid-juveniles) that displayed clear learning over sessions in order to assess effects of brief passive stimulus exposure on this learning. We compared learning in mid-juveniles exposed to either gap detection testing (gaps paired with startles) or equivalent gap exposure without testing (gaps alone) for three sessions. Learning was equivalent in both these groups and better than both naïve age-matched animals and controls receiving no gap exposure but only startle testing. Thus, short bouts of exposure to gaps independent of task performance is sufficient to induce learning at this age, and is as effective as gap detection testing. PMID:27378837

[Dosimetric system for assessing doses received by people occupationally exposed to external sources of ionizing radiation].

PubMed

Brodecki, Marcin; Domienik, Joanna U; Zmyślony, Marek

2012-01-01

The current system of dosimetric quantities has been defined by the International Commission on Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (ICRU). Complexity of the system implies the physical nature of ionizing radiation, resulting from the presence of different types of radiation of different ionization capabilities, as well as the individual radiation sensitivity of biological material exposed. According to the latest recommendations, there are three types of dosimeter quantities relevant to radiation protection and radiological assessment of occupational exposure. These are the basic quantities, safety quantities and operational quantities. Dose limits for occupational exposure relate directly to the protection quantities, i.e. the equivalent dose and effective dose, while these quantities are practically unmeasurable in real measurement conditions. For this reason, in the system of dosimetric quantities directly measurable operating volumes were defined. They represent equivalents of the protection quantities that allow for a reliable assessment of equivalent and effective dose by conducting routine monitoring of occupational exposure. This paper presents the characteristics of these quantities, their relationships and importance in assessing individual effects of radiation. Also the methods for their implementation in personal and environmental dosimetry were showcased. The material contained in the article is a compendium of essential information about dosimetric quantities with reference to the contemporary requirements of the law, including the changed annual occupational exposure limit for the lens of the eye. The material is especially addressed to those responsible for dosimetry monitoring in the workplace, radiation protection inspectors and occupational health physicians.

Sex differences in methamphetamine pharmacokinetics in adult rats and its transfer to pups through the placental membrane and breast milk.

PubMed

Rambousek, Lukas; Kacer, Petr; Syslova, Kamila; Bumba, Jakub; Bubenikova-Valesova, Vera; Slamberova, Romana

2014-06-01

Methamphetamine (METH) abuse is a growing health problem worldwide, and METH use during pregnancy not only endangers the mother's health but also the developing fetus. To provide better insight into these risks, we performed the following experiments. First, we investigated how sex influences the pharmacokinetics of METH and amphetamine (AMP) in male and female rats. Subsequently, we simulated chronic exposure of prenatal infants to METH abuse by investigating brain and plasma levels of METH and AMP in dams and pups. Finally, we modeled chronic exposure of infants to METH via breast milk and investigated sex differences in pups with regard to drug levels and possible sensitization effect of chronic prenatal METH co-treatment. We observed significantly higher levels of METH and AMP in the plasma and brain of female rats compared to males. Additionally, brain concentrations of METH and AMP in pups exposed to METH prenatally were equivalent to 62.13% and 37.78% relative to dam, respectively. Plasma concentrations of AMP where equivalent to 100% of the concentration in dams, while METH was equivalent to only 36.98%. Finally, we did not observe a significant effect relative to sex with regard to METH/AMP levels or sensitization effects linked to prenatal METH exposure. We demonstrated that female rats display higher levels of METH and AMP, thus indicating a greater risk of addiction and toxicity. Furthermore, our data show that pups are exposed to both METH and AMP following dam exposure. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Evaluation of bacterial kill when modelling the bronchopulmonary pharmacokinetic profile of moxifloxacin and levofloxacin against parC-containing isolates of Streptococcus pneumoniae.

PubMed

Deryke, C Andrew; Du, Xiaoli; Nicolau, David P

2006-09-01

The increasingly recognized prevalence of first-step parC mutants in Streptococcus pneumoniae and the development of de novo resistance while on fluoroquinolone therapy are of concern. Previous work by our group demonstrated the ability of moxifloxacin, but not levofloxacin, to eradicate parC mutants. The objective of this experiment was to determine whether these fluoroquinolone antibiotics provided equivalent bacterial kill when similar AUC/MICs were examined. An in vitro pharmacodynamic model was used to simulate the epithelial lining fluid (ELF) concentrations following oral administration of levofloxacin 500 mg once daily and moxifloxacin 400 mg once daily in older adults. In addition, a range of AUC/MICs were also modelled, including levofloxacin 750 mg once daily. Five different S. pneumoniae containing first-step parC mutations and one isolate without mutations were tested for 48 h and time-kill curves were constructed. Samples at 0, 24 and 48 h were collected for phenotypic and genotypic profiling. HPLC was used to verify that target exposures were achieved. The isolate without a parC mutation displayed a 4 log reduction in cfu after treatment with levofloxacin 500 mg and did not select for resistance. In all five isolates containing first-step parC mutations, resistance emerged within 48 h with a > or =16-fold increase in MIC and the acquisition of a gyrA mutant. Increasing the exposure of levofloxacin to approximately 750 mg dose still led to > or =16-fold increase in MIC at 48 h in two of the four isolates containing parC mutations. On the other hand, moxifloxacin 400 mg sustained bacterial killing against the two isolates tested without the selection of resistant mutants. It appears that the critical AUC/MIC necessary to prevent the acquisition of resistance for levofloxacin is 200 and approximately 400 for moxifloxacin. Due to suboptimal exposures, once-daily oral regimens of levofloxacin at both 500 and 750 mg inconsistently led to bactericidal activity and the frequent acquisition of a second-step gyrA mutation in S. pneumoniae isolates already containing a first-step parC mutation. Conversely, once-daily moxifloxacin 400 mg provides exposures that vastly exceed the apparent efficacy breakpoint and did not select for second-step mutants until exposures were decreased 4-fold. As a result of these data and the emerging literature involving mutations in the pneumococcus, caution should be exercised when the respiratory fluoroquinolones are used to treat patients infected with S. pneumoniae suspected of having parC mutations.

In vivo and phantom measurements of the secondary photon and neutron doses for prostate patients undergoing 18 MV IMRT.

PubMed

Reft, Chester S; Runkel-Muller, Renate; Myrianthopoulos, Leon

2006-10-01

For intensity modulated radiation therapy (IMRT) treatments 6 MV photons are typically used, however, for deep seated tumors in the pelvic region, higher photon energies are increasingly being employed. IMRT treatments require more monitor units (MU) to deliver the same dose as conformal treatments, causing increased secondary radiation to tissues outside the treated area from leakage and scatter, as well as a possible increase in the neutron dose from photon interactions in the machine head. Here we provide in vivo patient and phantom measurements of the secondary out-of-field photon radiation and the neutron dose equivalent for 18 MV IMRT treatments. The patients were treated for prostate cancer with 18 MV IMRT at institutions using different therapy machines and treatment planning systems. Phantom exposures at the different facilities were used to compare the secondary photon and neutron dose equivalent between typical IMRT delivered treatment plans with a six field three-dimensional conformal radiotherapy (3DCRT) plan. For the in vivo measurements LiF thermoluminescent detectors (TLDs) and Al2O3 detectors using optically stimulated radiation were used to obtain the photon dose and CR-39 track etch detectors were used to obtain the neutron dose equivalent. For the phantom measurements a Bonner sphere (25.4 cm diameter) containing two types of TLDs (TLD-600 and TLD-700) having different thermal neutron sensitivities were used to obtain the out-of-field neutron dose equivalent. Our results showed that for patients treated with 18 MV IMRT the photon dose equivalent is greater than the neutron dose equivalent measured outside the treatment field and the neutron dose equivalent normalized to the prescription dose varied from 2 to 6 mSv/Gy among the therapy machines. The Bonner sphere results showed that the ratio of neutron equivalent doses for the 18 MV IMRT and 3DCRT prostate treatments scaled as the ratio of delivered MUs. We also observed differences in the measured neutron dose equivalent among the three therapy machines for both the in vivo and phantom exposures.

Monte-Carlo and multi-exposure assessment for the derivation of criteria for disinfection byproducts and volatile organic compounds in drinking water: Allocation factors and liter-equivalents per day.

PubMed

Akiyama, Megumi; Matsui, Yoshihiko; Kido, Junki; Matsushita, Taku; Shirasaki, Nobutaka

2018-06-01

The probability distributions of total potential doses of disinfection byproducts and volatile organic compounds via ingestion, inhalation, and dermal exposure were estimated with Monte Carlo simulations, after conducting physiologically based pharmacokinetic model simulations to takes into account the differences in availability between the three exposures. If the criterion that the 95th percentile estimate equals the TDI (tolerable daily intake) is regarded as protecting the majority of a population, the drinking water criteria would be 140 (trichloromethane), 66 (bromodichloromethane), 157 (dibromochloromethane), 203 (tribromomethane), 140 (dichloroacetic acid), 78 (trichloroacetic acid), 6.55 (trichloroethylene, TCE), and 22 μg/L (perchloroethylene). The TCE criterion was lower than the Japanese Drinking Water Quality Standard (10 μg/L). The latter would allow the intake of 20% of the population to exceed the TDI. Indirect inhalation via evaporation from water, especially in bathrooms, was the major route of exposure to compounds other than haloacetic acids (HAAs) and accounted for 1.2-9 liter-equivalents/day for the median-exposure subpopulation. The ingestion of food was a major indirect route of exposure to HAAs. Contributions of direct water intake were not very different for trihalomethanes (30-45% of TDIs) and HAAs (45-52% of TDIs). Copyright © 2018 Elsevier Inc. All rights reserved.

Yurok Sentences.

ERIC Educational Resources Information Center

Bennett, Ruth, Ed.; And Others

A handlettered collection of approximately 220 commonly-used expressions and sentences in the language of the Yurok Indians of northwestern California includes common English equivalents as well as word-for-word translations. (LFL)

Glucocorticoid exposure and fracture risk in a cohort of US patients with selected conditions.

PubMed

Balasubramanian, A; Wade, S W; Adler, R A; Saag, K; Pannacciulli, N; Curtis, J R

2018-06-20

We evaluated systemic glucocorticoid exposure and fracture among patients with newly-diagnosed inflammatory and immune-modulated conditions. Using administrative data, inception cohorts of RA, asthma/COPD, IBD, MS, lupus, and sarcoidosis patients age 18-64 years with benefits coverage ≥12 months before diagnosis (1/1/2005-12/31/2012) were followed to clinical fracture, cancer diagnosis, or 12/31/2012. Glucocorticoid users were new to therapy. Fracture incidence rates (IR) per 1,000 person-years were stratified by prednisone equivalent doses. Cox's proportional hazards models assessed risk by daily and cumulative dose, and by time since discontinuation, adjusted for baseline characteristics. Most patients (72% of 403,337) had glucocorticoid exposure; 52% were under age 50. IR (95% confidence intervals [CI]) of any osteoporotic fracture was elevated at doses < 5 mg/day, IR: 9.33 [7.29, 11.77] versus 0 mg/day, IR: 4.87 [4.72, 5.02]). Fracture rates were elevated at doses < 5 mg/day in patients < 50 years and those ≥ 50 years. In both age groups, fracture risk increased with increasing cumulative exposure, being approximately 2.5-fold higher at cumulative dose ≥ 5400 mg compared to < 675 mg. At ≥ 5400 mg, IR were 5.69 [4.32, 7.35] in patients < 50 years and 17.10 [14.97, 19.46] in older patients. Fracture risk decreased significantly within months following glucocorticoid discontinuation. In patients with a variety of inflammatory conditions, fracture risk increased at doses as low as < 5 mg/day. Risk increased with increasing cumulative exposure and decreased soon following glucocorticoid discontinuation. Trends were similar between patients older and younger than 50 years. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Equivalent electron fluence for solar proton damage in GaAs shallow junction cells

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Stock, L. V.

1984-01-01

The short-circuit current reduction in GaAs shallow junction heteroface solar cells was calculated according to a simplified solar cell damage model in which the nonuniformity of the damage as a function of penetration depth is treated explicitly. Although the equivalent electron fluence was not uniquely defined for low-energy monoenergetic proton exposure, an equivalent electron fluence is found for proton spectra characteristic of the space environment. The equivalent electron fluence ratio was calculated for a typical large solar flare event for which the proton spectrum is PHI(sub p)(E) = A/E(p/sq. cm) where E is in MeV. The equivalent fluence ratio is a function of the cover glass shield thickness or the corresponding cutoff energy E(sub c). In terms of the cutoff energy, the equivalent 1 MeV electron fluence ratio is r(sub p)(E sub c) = 10(9)/E(sub c)(1.8) where E(sub c) is in units of KeV.

Risk Assessment of Face Skin Exposure to UV Irradiance from Different Rotation Angle Ranges

PubMed Central

Wang, Fang; Gao, Qian; Deng, Yan; Chen, Rentong; Liu, Yang

2017-01-01

Ultraviolet (UV) is one of the environmental pathogenic factors causing skin damage. Aiming to assess the risk of face skin exposure to UV irradiance from different rotation angles, a rotating model was used to monitor the exposure of the skin on the face to UV irradiance, with skin damage action spectra used to determine the biologically effective UV irradiance (UVBEskin) and UVBEskin radiant exposure (HBEskin) causing skin damage. The results indicate that the UVBEskin is directly influenced by variations in rotation angles. A significant decrease of approximately 52.70% and 52.10% in UVBEskin was found when the cheek and nose measurement sites was rotated from 0° to 90°, while a decrease of approximately 62.70% was shown when the forehead measurement sites was rotated from an angle of 0° to 108°. When HBEskin was compared to the exposure limits (ELs; 30 J·m−2), the maximum relative risk ratios (RR) for cheek, nose, and forehead were found to be approximately 2.01, 2.40, and 2.90, respectively, which were all measured at a rotation angle of 0°. The maximal increase in the percentage of the average HBEskin for rotation angles of 60°, 120°, 180°, and 360° facing the sun to ELs were found to be approximately 62.10%, 52.72%, 43.43%, and 26.27% for the cheek; approximately 130.61%, 109.68%, 86.43%, and 50.06% for the nose; and approximately 178.61%, 159.19%, 134.38%, and 83.41% for the forehead, respectively. PMID:28587318

Risk Assessment of Face Skin Exposure to UV Irradiance from Different Rotation Angle Ranges.

PubMed

Wang, Fang; Gao, Qian; Deng, Yan; Chen, Rentong; Liu, Yang

2017-06-06

Ultraviolet (UV) is one of the environmental pathogenic factors causing skin damage. Aiming to assess the risk of face skin exposure to UV irradiance from different rotation angles, a rotating model was used to monitor the exposure of the skin on the face to UV irradiance, with skin damage action spectra used to determine the biologically effective UV irradiance (UVBE skin ) and UVBE skin radiant exposure (HBE skin ) causing skin damage. The results indicate that the UVBE skin is directly influenced by variations in rotation angles. A significant decrease of approximately 52.70% and 52.10% in UVBE skin was found when the cheek and nose measurement sites was rotated from 0° to 90°, while a decrease of approximately 62.70% was shown when the forehead measurement sites was rotated from an angle of 0° to 108°. When HBE skin was compared to the exposure limits (ELs; 30 J·m -2 ), the maximum relative risk ratios (RR) for cheek, nose, and forehead were found to be approximately 2.01, 2.40, and 2.90, respectively, which were all measured at a rotation angle of 0°. The maximal increase in the percentage of the average HBE skin for rotation angles of 60°, 120°, 180°, and 360° facing the sun to ELs were found to be approximately 62.10%, 52.72%, 43.43%, and 26.27% for the cheek; approximately 130.61%, 109.68%, 86.43%, and 50.06% for the nose; and approximately 178.61%, 159.19%, 134.38%, and 83.41% for the forehead, respectively.

ISDD: A computational model of particle sedimentation, diffusion and target cell dosimetry for in vitro toxicity studies

PubMed Central

2010-01-01

Background The difficulty of directly measuring cellular dose is a significant obstacle to application of target tissue dosimetry for nanoparticle and microparticle toxicity assessment, particularly for in vitro systems. As a consequence, the target tissue paradigm for dosimetry and hazard assessment of nanoparticles has largely been ignored in favor of using metrics of exposure (e.g. μg particle/mL culture medium, particle surface area/mL, particle number/mL). We have developed a computational model of solution particokinetics (sedimentation, diffusion) and dosimetry for non-interacting spherical particles and their agglomerates in monolayer cell culture systems. Particle transport to cells is calculated by simultaneous solution of Stokes Law (sedimentation) and the Stokes-Einstein equation (diffusion). Results The In vitro Sedimentation, Diffusion and Dosimetry model (ISDD) was tested against measured transport rates or cellular doses for multiple sizes of polystyrene spheres (20-1100 nm), 35 nm amorphous silica, and large agglomerates of 30 nm iron oxide particles. Overall, without adjusting any parameters, model predicted cellular doses were in close agreement with the experimental data, differing from as little as 5% to as much as three-fold, but in most cases approximately two-fold, within the limits of the accuracy of the measurement systems. Applying the model, we generalize the effects of particle size, particle density, agglomeration state and agglomerate characteristics on target cell dosimetry in vitro. Conclusions Our results confirm our hypothesis that for liquid-based in vitro systems, the dose-rates and target cell doses for all particles are not equal; they can vary significantly, in direct contrast to the assumption of dose-equivalency implicit in the use of mass-based media concentrations as metrics of exposure for dose-response assessment. The difference between equivalent nominal media concentration exposures on a μg/mL basis and target cell doses on a particle surface area or number basis can be as high as three to six orders of magnitude. As a consequence, in vitro hazard assessments utilizing mass-based exposure metrics have inherently high errors where particle number or surface areas target cells doses are believed to drive response. The gold standard for particle dosimetry for in vitro nanotoxicology studies should be direct experimental measurement of the cellular content of the studied particle. However, where such measurements are impractical, unfeasible, and before such measurements become common, particle dosimetry models such as ISDD provide a valuable, immediately useful alternative, and eventually, an adjunct to such measurements. PMID:21118529

Inadvertent Intruder Analysis For The Portsmouth On-Site Waste Disposal Facility (OSWDF)

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

Smith, Frank G.; Phifer, Mark A.

2014-01-22

The inadvertent intruder analysis considers the radiological impacts to hypothetical persons who are assumed to inadvertently intrude on the Portsmouth OSWDF site after institutional control ceases 100 years after site closure. For the purposes of this analysis, we assume that the waste disposal in the OSWDF occurs at time zero, the site is under institutional control for the next 100 years, and inadvertent intrusion can occur over the following 1,000 year time period. Disposal of low-level radioactive waste in the OSWDF must meet a requirement to assess impacts on such individuals, and demonstrate that the effective dose equivalent to anmore » intruder would not likely exceed 100 mrem per year for scenarios involving continuous exposure (i.e. chronic) or 500 mrem for scenarios involving a single acute exposure. The focus in development of exposure scenarios for inadvertent intruders was on selecting reasonable events that may occur, giving consideration to regional customs and construction practices. An important assumption in all scenarios is that an intruder has no prior knowledge of the existence of a waste disposal facility at the site. Results of the analysis show that a hypothetical inadvertent intruder at the OSWDF who, in the worst case scenario, resides on the site and consumes vegetables from a garden established on the site using contaminated soil (chronic agriculture scenario) would receive a maximum chronic dose of approximately 7.0 mrem/yr during the 1000 year period of assessment. This dose falls well below the DOE chronic dose limit of 100 mrem/yr. Results of the analysis also showed that a hypothetical inadvertent intruder at the OSWDF who, in the worst case scenario, excavates a basement in the soil that reaches the waste (acute basement construction scenario) would receive a maximum acute dose of approximately 0.25 mrem/yr during the 1000 year period of assessment. This dose falls well below the DOE acute dose limit of 500 mrem/yr. Disposal inventory constraints based on the intruder analysis are well above conservative estimates of the OSWDF inventory and, based on intruder disposal limits; about 7% of the disposal capacity is reached with the estimated OSWDF inventory.« less

Optimal shielding thickness for galactic cosmic ray environments

NASA Astrophysics Data System (ADS)

Slaba, Tony C.; Bahadori, Amir A.; Reddell, Brandon D.; Singleterry, Robert C.; Clowdsley, Martha S.; Blattnig, Steve R.

2017-02-01

Models have been extensively used in the past to evaluate and develop material optimization and shield design strategies for astronauts exposed to galactic cosmic rays (GCR) on long duration missions. A persistent conclusion from many of these studies was that passive shielding strategies are inefficient at reducing astronaut exposure levels and the mass required to significantly reduce the exposure is infeasible, given launch and associated cost constraints. An important assumption of this paradigm is that adding shielding mass does not substantially increase astronaut exposure levels. Recent studies with HZETRN have suggested, however, that dose equivalent values actually increase beyond ∼20 g/cm2 of aluminum shielding, primarily as a result of neutron build-up in the shielding geometry. In this work, various Monte Carlo (MC) codes and 3DHZETRN are evaluated in slab geometry to verify the existence of a local minimum in the dose equivalent versus aluminum thickness curve near 20 g/cm2. The same codes are also evaluated in polyethylene shielding, where no local minimum is observed, to provide a comparison between the two materials. Results are presented so that the physical interactions driving build-up in dose equivalent values can be easily observed and explained. Variation of transport model results for light ions (Z ≤ 2) and neutron-induced target fragments, which contribute significantly to dose equivalent for thick shielding, is also highlighted and indicates that significant uncertainties are still present in the models for some particles. The 3DHZETRN code is then further evaluated over a range of related slab geometries to draw closer connection to more realistic scenarios. Future work will examine these related geometries in more detail.

Optimal shielding thickness for galactic cosmic ray environments.

PubMed

Slaba, Tony C; Bahadori, Amir A; Reddell, Brandon D; Singleterry, Robert C; Clowdsley, Martha S; Blattnig, Steve R

2017-02-01

Models have been extensively used in the past to evaluate and develop material optimization and shield design strategies for astronauts exposed to galactic cosmic rays (GCR) on long duration missions. A persistent conclusion from many of these studies was that passive shielding strategies are inefficient at reducing astronaut exposure levels and the mass required to significantly reduce the exposure is infeasible, given launch and associated cost constraints. An important assumption of this paradigm is that adding shielding mass does not substantially increase astronaut exposure levels. Recent studies with HZETRN have suggested, however, that dose equivalent values actually increase beyond ∼20g/cm 2 of aluminum shielding, primarily as a result of neutron build-up in the shielding geometry. In this work, various Monte Carlo (MC) codes and 3DHZETRN are evaluated in slab geometry to verify the existence of a local minimum in the dose equivalent versus aluminum thickness curve near 20g/cm 2 . The same codes are also evaluated in polyethylene shielding, where no local minimum is observed, to provide a comparison between the two materials. Results are presented so that the physical interactions driving build-up in dose equivalent values can be easily observed and explained. Variation of transport model results for light ions (Z ≤ 2) and neutron-induced target fragments, which contribute significantly to dose equivalent for thick shielding, is also highlighted and indicates that significant uncertainties are still present in the models for some particles. The 3DHZETRN code is then further evaluated over a range of related slab geometries to draw closer connection to more realistic scenarios. Future work will examine these related geometries in more detail. Published by Elsevier Ltd.

Grape cluster microclimate influences the aroma composition of Sauvignon blanc wine.

PubMed

Martin, Damian; Grose, Claire; Fedrizzi, Bruno; Stuart, Lily; Albright, Abby; McLachlan, Andrew

2016-11-01

New Zealand Sauvignon blanc (SB) wines are characterised by a distinctive combination of tropical-fruity and green-herbaceous aromatic compounds. The influence of sunlight exposure of grape clusters on juice and wine composition was investigated, with the aim of manipulating aromatic compounds in SB wine. In the absence of basal leaf removal SB clusters naturally exposed to sunlight were riper than shaded clusters, evidenced by higher total soluble solids (TSS) and proline, and lower malic acid, 3-isobutyl-2-methoxypyrazine (IBMP) and arginine. Volatile thiols in wines did not differ between shaded and exposed clusters. At equivalent TSS, cluster exposure had little or no effect on malic acid concentration. Conversely, wine from shaded clusters had almost double the IBMP concentration of wine from exposed clusters at equivalent TSS. The effects on SB juice and wine composition of natural variations in cluster microclimate are not comparable with the effects of cluster exposure created through leaf removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Doctor Shopping Behavior and the Diversion of Prescription Opioids.

PubMed

Simeone, Ronald

2017-01-01

"Doctor shopping" as a means of prescription opioid diversion is examined. The number and percentage of prescriptions and morphine-equivalent milligrams diverted in this manner are estimated by state and molecule for the period 2008-2012. Eleven billion prescriptions with unique patient, doctor, and pharmacy identifiers were used to construct diversion "events" that involved between 1 and 6 unique doctors and between 1 and 6 unique pharmacies. Diversion thresholds were established based on the probability of each contingency. A geographically widespread decline occurred between 2008 and 2012. The number of prescriptions diverted fell from approximately 4.30 million (1.75% of all prescriptions) in 2008 to approximately 3.37 million (1.27% of all prescriptions) in 2012, and the number of morphine-equivalent milligrams fell from approximately 6.55 metric tons (2.95% of total metric tons) in 2008 to approximately 4.87 metric tons (2.19% of total metric tons) in 2012. Diversion control efforts have likely been effective. But given increases in opioid-related deaths, opioid-related drug treatment admissions, and the more specific resurgence of heroin-related events, it is clear that additional public health measures are required.

Conceptual Design of Low-Boom Aircraft with Flight Trim Requirement

NASA Technical Reports Server (NTRS)

Ordaz, Irian; Geiselhart, Karl A.; Fenbert, James W.

2014-01-01

A new low-boom target generation approach is presented which allows the introduction of a trim requirement during the early conceptual design of supersonic aircraft. The formulation provides an approximation of the center of pressure for a presumed aircraft configuration with a reversed equivalent area matching a low-boom equivalent area target. The center of pressure is approximated from a surrogate lift distribution that is based on the lift component of the classical equivalent area. The assumptions of the formulation are verified to be sufficiently accurate for a supersonic aircraft of high fineness ratio through three case studies. The first two quantify and verify the accuracy and the sensitivity of the surrogate center of pressure corresponding to shape deformation of lifting components. The third verification case shows the capability of the approach to achieve a trim state while maintaining the low-boom characteristics of a previously untrimmed configuration. Finally, the new low-boom target generation approach is demonstrated through the early conceptual design of a demonstrator concept that is low-boom feasible, trimmed, and stable in cruise.

Fast simulation techniques for switching converters

NASA Technical Reports Server (NTRS)

King, Roger J.

1987-01-01

Techniques for simulating a switching converter are examined. The state equations for the equivalent circuits, which represent the switching converter, are presented and explained. The uses of the Newton-Raphson iteration, low ripple approximation, half-cycle symmetry, and discrete time equations to compute the interval durations are described. An example is presented in which these methods are illustrated by applying them to a parallel-loaded resonant inverter with three equivalent circuits for its continuous mode of operation.

Hair mercury levels in relation to fish consumption among Vietnamese in Hanoi.

PubMed

Hoang, Van Anh Thi; Do, Hien Thu Thi; Agusa, Tetsuro; Koriyama, Chihaya; Akiba, Suminori; Ishibashi, Yasuhiro; Sakamoto, Mineshi; Yamamoto, Megumi

2017-01-01

People are exposed to methylmercury (MeHg) mainly through fish consumption, which is increasing in Vietnam. However, little information is available on estimating the health risk of MeHg exposure through fish consumption in Vietnam. The present study examined the association between mercury (Hg) levels in hair and selenium (Se) levels in toenails of 196 Vietnamese people and their fish consumption, using a dietary questionnaire to obtain information pertinent for assessing health risk owing to MeHg exposure. The geometric mean of Hg levels in the hair of males and females was 617 ng/g and 575 ng/g, respectively. We found that Hg levels in the hair of 98% of the Vietnamese study subjects were lower than the provisional tolerable weekly intake for MeHg (1.6 µg Hg/kg body weight; which is equivalent to a hair Hg concentration of approximately 2,300 ng/g, with an uncertainty factor of 6.4). There were significant differences in the age-adjusted geometric mean of Hg levels found in hair from females related to their frequency of freshwater fish consumption. The levels of Hg in hair and Se in toenails increased with an increased frequency of marine fish consumption, and both showed a significant positive correlation in subjects who consumed marine fish ≥ once/week. This is the first cross-sectional study to investigate the association between hair Hg levels and fish consumption in Vietnam. These findings provide valuable information for future assessments of the health risk of MeHg exposure through fish consumption in Vietnam.

Impact of atmospheric particulate matter pollutants to IAQ of airport terminal buildings: A first field study at Tianjin Airport, China

NASA Astrophysics Data System (ADS)

Ren, Jianlin; Cao, Xiaodong; Liu, Junjie

2018-04-01

Passengers usually spend hours in the airport terminal buildings waiting for their departure. During the long waiting period, ambient fine particles (PM2.5) and ultrafine particles (UFP) generated by airliners may penetrate into terminal buildings through open doors and the HVAC system. However, limited data are available on passenger exposure to particulate pollutants in terminal buildings. We conducted on-site measurements on PM2.5 and UFP concentration and the particle size distribution in the terminal building of Tianjin Airport, China during three different seasons. The results showed that the PM2.5 concentrations in the terminal building were considerably larger than the values guided by Chinese standard and WHO on all of the tested seasons, and the conditions were significantly affected by the outdoor air (Spearman test, p < 0.01). The indoor/outdoor PM2.5 ratios (I/O) ranged from 0.67 to 0.84 in the arrival hall and 0.79 to 0.96 in the departure hall. The particle number concentration in the terminal building presented a bi-modal size distribution, with one mode being at 30 nm and another mode at 100 nm. These results were totally different from the size distribution measured in a normal urban environment. The total UFP exposure during the whole waiting period (including in the terminal building and airliner cabin) of a passenger is approximately equivalent to 11 h of exposure to normal urban environments. This study is expected to contribute to the improvement of indoor air quality and health of passengers in airport terminal buildings.

Chemical regulation of polyethism during foraging in the neotropical termiteNasutitermes costalis.

PubMed

Traniello, J F; Busher, C

1985-03-01

The soldiers ofNasutitermes costalis communicate information about the presence and location of food by laying chemical trails of sternal gland secretion. These trails first recruit additional soldiers, and as the number of soldiers contacting food and returning to the nest increases, trail pheromone concentration increases, and workers are recruited. This polyethic pattern of recruitment does not appear to depend on qualitative (caste-specific) properties of soldier and worker sternal gland secretions, but rather on quantitative differences in pheromone production between castes. Large third-instar workers have significantly greater sternal gland volumes than soldiers, and glands of approximately equivalent size have approximately equivalent recruitment effects. The recruitment and orientation effects of artificial trails prepared from worker sternal glands can be mimicked by increasing the concentration of soldier sternal gland pheromone.

A computational algorithm for spacecraft control and momentum management

NASA Technical Reports Server (NTRS)

Dzielski, John; Bergmann, Edward; Paradiso, Joseph

1990-01-01

Developments in the area of nonlinear control theory have shown how coordinate changes in the state and input spaces of a dynamical system can be used to transform certain nonlinear differential equations into equivalent linear equations. These techniques are applied to the control of a spacecraft equipped with momentum exchange devices. An optimal control problem is formulated that incorporates a nonlinear spacecraft model. An algorithm is developed for solving the optimization problem using feedback linearization to transform to an equivalent problem involving a linear dynamical constraint and a functional approximation technique to solve for the linear dynamics in terms of the control. The original problem is transformed into an unconstrained nonlinear quadratic program that yields an approximate solution to the original problem. Two examples are presented to illustrate the results.

Safety, Tolerability, and Pharmacokinetic Properties of Intravenous Delafloxacin After Single and Multiple Doses in Healthy Volunteers.

PubMed

Hoover, Randall; Hunt, Thomas; Benedict, Michael; Paulson, Susan K; Lawrence, Laura; Cammarata, Sue; Sun, Eugene

2016-01-01

The objective of this report was to determine the pharmacokinetic properties, safety, and tolerability of single and multiple doses of intravenous delafloxacin. In addition, the absolute bioavailability (BA) of the 450-mg tablet formulation of delafloxacin was determined. Three clinical trials are summarized. The first study was a randomized, double-blind, placebo-controlled, single- (300, 450, 600, 750, 900, and 1200 mg) ascending-dose study of IV delafloxacin in 62 (52 active, 10 placebo) healthy volunteers. The second study was a randomized, double-blind, placebo-controlled study of IV delafloxacin (300 mg) given as a single dose on day 1, followed by twice-daily dosing on days 2 through 14; 12 (8 active, 4 placebo) healthy volunteers were enrolled. The third study was an open-label, randomized, 2-period, 2-sequence crossover study in which 56 healthy volunteers were randomly assigned to 1 of 2 sequences of a single oral dose of delafloxacin (450-mg tablet) or IV delafloxacin (300 mg). Serial blood samples were collected, and plasma pharmacokinetic parameters of delafloxacin were calculated. Delafloxacin Cmax values increased proportionally with increasing single IV dose for the dose range of 300 to 1200 mg, whereas the AUC values increased more than proportionally to dose for the same dose range. The mean terminal half-life of delafloxacin was approximately 12 hours (ranging from 8 to 17 hours). The volume of distribution (Vd) at steady state was approximately 35 L, which is similar to the volume of total body water. There was minimal accumulation of delafloxacin after twice-daily IV administration of 300 mg with an accumulation ratio of 1.09. The delafloxacin total exposure after a single 1-hour IV infusion of 300 mg and a single oral dose of a 450-mg tablet were equivalent with geometric least square mean ratio (90% CI) of 0.8768 (0.8356-0.9200) for AUC0-∞ and 0.8445 (0.8090-0.8815) for AUC0-t, respectively. The Cmax values of delafloxacin were not equivalent for the 2 formulations with a ratio (90% CI) of 0.5516 (0.5150-0.5908), respectively. The mean absolute bioavailability of delafloxacin was 58.8%. Delafloxacin was well tolerated in healthy volunteers after single and multiple IV doses. The total systemic exposure to IV (300 mg) and oral (450 mg) delafloxacin is comparable, supporting that a switch between the 2 formulations is appropriate. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Comparison of secondary organic aerosol formed with an aerosol flow reactor and environmental reaction chambers: effect of oxidant concentration, exposure time and seed particles on chemical composition and yield

NASA Astrophysics Data System (ADS)

Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.; Brune, W. H.; Hunter, J. F.; Kroll, J. H.; Cummings, M. J.; Brogan, J. F.; Parmar, Y.; Worsnop, D. R.; Kolb, C. E.; Davidovits, P.

2014-12-01

We performed a systematic intercomparison study of the chemistry and yields of SOA generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0×108 to 2.2×1010 molec cm-3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2×106 to 2×107 molec cm-3 over exposure times of several hours. The OH concentration in the chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. A linear correlation analysis of the mass spectra (m=0.91-0.92, r2=0.93-0.94) and carbon oxidation state (m=1.1, r2=0.58) of SOA produced in the flow reactor and environmental chambers for OH exposures of approximately 1011 molec cm-3 s suggests that the composition of SOA produced in the flow reactor and chambers is the same within experimental accuracy as measured with an aerosol mass spectrometer. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors, rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed particles are routinely used.

Marijuana

MedlinePlus

... decline in general knowledge and in verbal ability (equivalent to 4 IQ points) between the preteen years ... Cone EJ, Bigelow GE, Herrmann ES, et al. Non-smoker exposure to secondhand cannabis smoke. I. Urine ...

Effects of High Sound Exposure During Air-Conducted Vestibular Evoked Myogenic Potential Testing in Children and Young Adults.

PubMed

Rodriguez, Amanda I; Thomas, Megan L A; Fitzpatrick, Denis; Janky, Kristen L

Vestibular evoked myogenic potential (VEMP) testing is increasingly utilized in pediatric vestibular evaluations due to its diagnostic capability to identify otolith dysfunction and feasibility of testing. However, there is evidence demonstrating that the high-intensity stimulation level required to elicit a reliable VEMP response causes acoustic trauma in adults. Despite utility of VEMP testing in children, similar findings are unknown. It is hypothesized that increased sound exposure may exist in children because differences in ear-canal volume (ECV) compared with adults, and the effect of stimulus parameters (e.g., signal duration and intensity) will alter exposure levels delivered to a child's ear. The objectives of this study are to (1) measure peak to peak equivalent sound pressure levels (peSPL) in children with normal hearing (CNH) and young adults with normal hearing (ANH) using high-intensity VEMP stimuli, (2) determine the effect of ECV on peSPL and calculate a safe exposure level for VEMP, and (3) assess whether cochlear changes exist after VEMP exposure. This was a 2-phase approach. Fifteen CNH and 12 ANH participated in phase I. Equivalent ECV was measured. In 1 ear, peSPL was recorded for 5 seconds at 105 to 125 dB SPL, in 5-dB increments for 500- and 750-Hz tone bursts. Recorded peSPL values (accounting for stimulus duration) were then used to calculate safe sound energy exposure values for VEMP testing using the 132-dB recommended energy allowance from the 2003 European Union Guidelines. Fifteen CNH and 10 ANH received cervical and ocular VEMP testing in 1 ear in phase II. Subjects completed tympanometry, pre- and postaudiometric threshold testing, distortion product otoacoustic emissions, and questionnaire addressing subjective otologic symptoms to study the effect of VEMP exposure on cochlear function. (1) In response to high-intensity stimulation levels (e.g., 125 dB SPL), CNH had significantly higher peSPL measurements and smaller ECVs compared with ANH. (2) A significant linear relationship between equivalent ECV (as measured by diagnostic tympanometry) and peSPL exists and has an effect on total sound energy exposure level; based on data from phase I, 120 dB SPL was determined to be an acoustically safe stimulation level for testing in children. (3) Using calculated safe stimulation level for VEMP testing, there were no significant effect of VEMP exposure on cochlear function (as measured by audiometric thresholds, distortion product otoacoustic emission amplitude levels, or subjective symptoms) in CNH and ANH. peSPL sound recordings in children's ears are significantly higher (~3 dB) than that in adults in response to high-intensity VEMP stimuli that are commonly practiced. Equivalent ECV contributes to peSPL delivered to the ear during VEMP testing and should be considered to determine safe acoustic VEMP stimulus parameters; children with smaller ECVs are at risk for unsafe sound exposure during routine VEMP testing, and stimuli should not exceed 120 dB SPL. Using 120 dB SPL stimulus level for children during VEMP testing yields no change to cochlear function and reliable VEMP responses.

IL-11, IL-1α, IL-6, and TNF-α are induced by solar radiation in vitro and may be involved in facial subcutaneous fat loss in vivo.

PubMed

Li, Wen-Hwa; Pappas, Apostolos; Zhang, Li; Ruvolo, Eduardo; Cavender, Druie

2013-07-01

The loss of subcutaneous (sc) fat is associated with aging. Inflammatory cytokines, such as interleukin-1 α (IL-1α), interleukin-11 (IL-11) and tumor necrosis factor-α (TNF-α), are known to inhibit the differentiation of preadipocytes. This study investigated the potential role of inflammatory cytokines in solar-radiation-induced facial fat loss. Cultured fibroblasts, keratinocytes, and skin equivalents were exposed to various doses of radiation from a solar simulator. Inflammatory cytokines' mRNA production and protein secretion were examined by qRT-PCR and ELISA, respectively. In some experiments, epidermal-dermal equivalents were pretreated topically with a broad-spectrum sunscreen prior to solar simulated radiation (SSR). Human facial preadipocytes treated with recombinant IL-11 or with conditioned media from solar-irradiated equivalents were evaluated for the level of adipocyte differentiation by image analyses, Oil red O staining, and the expression of adipocyte differentiation markers. IL-11, IL-1α, IL-6, and TNF-α protein secretion were induced from epidermal-dermal equivalents by exposure to SSR. A sunscreen prevented SSR-induced inflammatory cytokines production from such equivalents. Exposure of facial preadipocytes to conditioned medium from solar-irradiated epidermal-dermal equivalents inhibited their differentiation into mature adipocytes. Consequently, conditioned medium from sunscreen-pretreated, solar-irradiated equivalents did not inhibit differentiation of preadipocytes. A cocktail of neutralizing antibodies to IL-11, IL-1α, IL-6 and TNF-α significantly reduced the SSR-induced inhibition of preadipocyte differentiation. These results support the hypothesis that SSR-induced inflammatory cytokine may be involved in the photoaging-induced loss of facial subcutaneous fat. Inhibition of this process, e.g. by sunscreens, might slow or prevent photoaging-induced changes in facial contouring. Copyright © 2013 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

Determination of Important Nuclear Fragmentation Processes for Human Space Radiation Protection

NASA Technical Reports Server (NTRS)

Lin, Zi-Wei

2007-01-01

We present a semi-analytical method to determine which partial cross sections of nuclear fragmentations most affect the shielded dose equivalent due to exposure to galactic cosmic rays. The cross sections thus determined will require more theoretical and/or experimental studies in order for us to better predict, reduce and mitigate the radiation exposure in human space explorations.

UV EFFECTS IN TOOTH ENAMEL AND THEIR POSSIBLE APPLICATION IN EPR DOSIMETRY WITH FRONT TEETH

PubMed Central

Sholom, S.; Desrosiers, M.; Chumak, V.; Luckyanov, N.; Simon, S.L.; Bouville, A.

2009-01-01

The effects of ultraviolet (UV) radiation on ionizing radiation biodosimetry were studied in human tooth enamel samples using the technique of electron paramagnetic resonance (EPR) in X-band. For samples in the form of grains, UV-specific EPR spectra were spectrally distinct from that produced by exposure to gamma radiation. From larger enamel samples, the UV penetration depth was determined to be in the 60–120 μm range. The difference in EPR spectra from UV exposure and from exposure to gamma radiation samples was found to be a useful marker of UV equivalent dose (defined as the apparent contribution to the gamma dose in mGy that results from UV radiation absorption) in tooth enamel. This concept was preliminarily tested on front teeth from inhabitants of the region of the Semipalatinsk Nuclear Test Site (Kazakhstan) who might have received some exposure to gamma radiation from the nuclear tests conducted there as well as from normal UV radiation in sunlight. The technique developed here to quantify and subtract the UV contribution to the measured tooth is currently limited to cumulative dose measurements with a component of UV equivalent dose equal to or greater than 300 mGy. PMID:20065706

Human exposure to large solar particle events in space

NASA Technical Reports Server (NTRS)

Townsend, L. W.; Wilson, J. W.; Shinn, J. L.; Curtis, S. B.

1992-01-01

Whenever energetic solar protons produced by solar particle events traverse bulk matter, they undergo various nuclear and atomic collision processes which significantly alter the physical characteristics and biologically important properties of their transported radiation fields. These physical interactions and their effect on the resulting radiation field within matter are described within the context of a recently developed deterministic, coupled neutron-proton space radiation transport computer code (BRYNTRN). Using this computer code, estimates of human exposure in interplanetary space, behind nominal (2 g/sq cm) and storm shelter (20 g/sq cm) thicknesses of aluminum shielding, are made for the large solar proton event of August 1972. Included in these calculations are estimates of cumulative exposures to the skin, ocular lens, and bone marrow as a function of time during the event. Risk assessment in terms of absorbed dose and dose equivalent is discussed for these organs. Also presented are estimates of organ exposures for hypothetical, worst-case flare scenarios. The rate of dose equivalent accumulation places this situation in an interesting region of dose rate between the very low values of usual concern in terrestrial radiation environments and the high-dose-rate values prevalent in radiation therapy.

Counteracting tobacco motor sports sponsorship as a promotional tool: is the tobacco settlement enough?

PubMed Central

Siegel, M

2001-01-01

OBJECTIVES: This study sought to quantify television advertising exposure achieved by tobacco companies through sponsorship of motor sports events and to evaluate the likely effect of the Master Settlement Agreement on this advertising. METHODS: Data from Sponsors Report, which quantifies the exposure that sponsors of selected televised sporting events receive during broadcasts of those events, were compiled for all motor sports events covered by the service for the period 1997 through 1999. RESULTS: From 1997 through 1999, tobacco companies achieved 169 hours of television advertising exposure and $410.5 million of advertising value for their products by sponsoring motor sports events. If tobacco companies comply with the Master Settlement Agreement and maintain their advertising at 1999 levels, they will still be able to achieve more than 25 hours of television exposure and an equivalent television advertising value of $99.1 million per year. CONCLUSIONS: Despite a federal ban on tobacco advertising on television, tobacco companies achieve the equivalent of more than $150 million in television advertising per year through their sponsorship of motor sports events. The Master Settlement Agreement likely will do little to address this problem. PMID:11441738

The broad-band x ray spectral variability of Mkn 841

NASA Technical Reports Server (NTRS)

George, I. M.; Nandra, K.; Fabian, A. C.; Turner, T. J.; Done, C.; Day, C. S. R.

1992-01-01

The results of a detailed spectral analysis of four X-ray observations of the luminous Seyfert 1.5 galaxy Mkn 841 performed using the EXOSAT and Ginga satellites over the period June 1984 to July 1990 are reported. Preliminary results from a short ROSAT PSPC observation of Mkn 841 in July 1990 are also presented. Variability is apparent in both the soft (0.1-1.0 keV) and medium (1-20 keV) energy bands. Above 1 keV, the spectra are adequately modelled by a power-law with a strong emission line of equivalent width approximately 450 eV. The energy of the line (approximately 6.4 keV) is indicative of K-shell fluorescence from neutral iron, leading to the interpretation that the line arises via X-ray illumination of cold material surrounding the source. In addition to the flux variability, the continuum shape also changes in a dramatic fashion, with variations in the apparent photon index Delta(Gamma) approximately 0.6. The large equivalent width of the emission line clearly indicates a strongly enhanced reflection component in the source, compared to other Seyferts observed with Ginga. The spectral changes are interpreted in terms of a variable power-law continuum superimposed on a flatter reflection component. For one Ginga observation, the reflected flux appears to dominate the medium energy X-ray emission, resulting in an unusually flat slope (Gamma approximately 1.0). The soft X-ray excess is found to be highly variable by a factor approximately 10. These variations are not correlated with the hard flux, but it seems likely that the soft component arises via reprocessing of the hard X-rays. We find no evidence for intrinsic absorption, with the equivalent hydrogen column density constrained to be less than or equal to few x 10(exp 20) cm(exp -2). The implications of these results for physical models for the emission regions in this and other X-ray bright Seyferts are briefly discussed.

Ambient Dose Equivalent in S. Paulo and Bauru cities

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

Umisedo, Nancy K.; Okuno, Emico; Cancio, Francisco S.

2008-08-07

The Laboratory of Dosimetry (Institute of Physics, University of S. Paulo) performs since 1981 the external individual monitoring of workers exposed to X and gamma rays based on thermoluminescent dosimetry (TLD). Personal dose equivalent refers only to the exposure of workers due to the working activities, and the dose due to background radiation, also measured with TLD, must be subtracted to evaluate it. A compilation of ambient dose equivalent was done to evaluate the dose due to the background radiation in the work places, and also to contribute to the knowledge of the level of indoor radiation to which themore » public is exposed.« less

Chronic Myeloid Leukemia

MedlinePlus

... medication. Protein Synthesis Inhibitor Therapy. Omacetaxine (Synribo®) a non-TKI, chemotherapy drug, is approved for chronic and ... as BCR-ABL 10%. This reduction is approximately equivalent to a major cytogenetic response. {{ A 2-log ...

Are Early-Life Socioeconomic Conditions Directly Related to Birth Outcomes? Grandmaternal Education, Grandchild Birth Weight, and Associated Bias Analyses

PubMed Central

Huang, Jonathan Y.; Gavin, Amelia R.; Richardson, Thomas S.; Rowhani-Rahbar, Ali; Siscovick, David S.; Enquobahrie, Daniel A.

2015-01-01

Grandmaternal education may be related to grandchild birth weight (GBW) through maternal early-life development; however, conventional regression models may be endogenously confounded. Alternative models employing explicit structural assumptions may provide incrementally clearer evidence. We used data from the US National Longitudinal Study of Adolescent to Adult Health (1995–2009; 1,681 mother-child pairs) to estimate “direct effects” of grandmaternal educational level (less than high school, high school diploma or equivalent, or college degree) at the time of the mother's birth on GBW, adjusted for maternal life-course factors: maltreatment as a child, education and income as an adult, prepregnancy overweight, and prenatal smoking. Using conventional and marginal structural model (MSM) approaches, we estimated 54-g (95% confidence interval: −14.0, 122.1) and 87-g (95% confidence interval: 10.9, 162.5) higher GBWs per increase in educational level, respectively. The MSM allowed simultaneous mediation by and adjustment for prepregnancy overweight. Estimates were insensitive to alternate structural assumptions and mediator parameterizations. Bias analysis suggested that a single unmeasured confounder would have to have a strong influence on GBW (approximately 150 g) or be greatly imbalanced across exposure groups (approximately 25%) to completely explain the findings. Coupling an MSM with sensitivity analyses provides some evidence that maternal early-life socioeconomic environment is directly associated with offspring birth weight. PMID:26283086

Fall with Linear Drag and Wien's Displacement Law: Approximate Solution and Lambert Function

ERIC Educational Resources Information Center

Vial, Alexandre

2012-01-01

We present an approximate solution for the downward time of travel in the case of a mass falling with a linear drag force. We show how a quasi-analytical solution implying the Lambert function can be found. We also show that solving the previous problem is equivalent to the search for Wien's displacement law. These results can be of interest for…

[Some aspects of animal-to-human approximation of low frequency electromagnetic field exposure conditions].

PubMed

Vasin, A L

2003-01-01

Appropriateness of representation of a biological object surface as an equipotential surface has been proved for conditions of a quasistatic exposure to EMF of frequencies lower than 1 MHz. The conditions, at which a self capacitance of a biological object is its basic electrical parameter, have been considered. A factor of animal-to-human approximation of low-frequency EMF exposure conditions was estimated on the basis of equal dose loading in biological objects of different geometric sizes.

Pattern of dental caries experience on tooth surfaces in an adult population.

PubMed

Hopcraft, Matthew Scott; Morgan, Michael Vivian

2006-06-01

To determine the pattern of caries experience across teeth and surfaces in an adult population depending on age and exposure to water fluoridation. Between November 2002 and March 2003 a total of 973 subjects aged 17-51 years had a clinical examination using visual and tactile criteria. Subsequent to this examination, bitewing radiographs were taken and viewed separately. Approximal and occlusal surfaces of molars and premolars were examined on the radiographs. Caries experience was relatively low, with mean DMFS scores of 3.21, 5.12, 9.61, 13.04 and 24.35 for subjects aged 17-20, 21-25, 26-30, 31-35 and 36-51 years respectively. The first molar teeth had the greatest caries experience, and occlusal surfaces had more caries experience than approximal surfaces. Subjects with a lifetime exposure to fluoridated drinking water had significantly lower caries experience than those who had no exposure to fluoridated drinking water. This study showed that caries prevalence, although relatively low in the study population, was found predominantly in occlusal surfaces, with an increasing prevalence in approximal surfaces of posterior teeth in older subjects. Subjects with a lifetime exposure to fluoridated drinking water had a lower level of caries experience than those with no exposure to fluoridated drinking water, and this was more noticeable in approximal surfaces than occlusal surfaces.

Engineering experimental program on the effects of near-space radiation on lithium doped solar cells

NASA Technical Reports Server (NTRS)

1971-01-01

The results of an experimental evaluation of the real-time degradation characteristics of lithium-diffused silicon solar cells are reported. A strontium-90 radioisotope was used for simulation of a typical earth-orbital electron environment. The experiment was performed in an ion pump vacuum chamber with samples maintained at -50, +20, +50, and +80 C. Samples were illuminated during the 6-month exposure run with solar cell 1-5 characteristics measured periodically in situ. This 6-month exposure corresponded to a 1 MeV equivalent fluence of approximately 10 to the 14th power electrons/sq cm. Several types of lithium cells were irradiatied and compared directly with conventional N/P cells. The best lithium cells compared favorably with N/P cells, particularly at the higher test temperatures. With a slight improvement of initial performance characteristics, lithium cells appear feasible for 5 to 10 year missions at synchronous altitude. Based on the reported results and those of other irradiation experiments, lithium cells would appear to be superior to N/P cells in proton-dominated earth-orbital environments. Another important conclusion of the effort was that illuminated/loaded cells degrade more rapidly than do dark/unloaded cells. The irradiation experiment provided data of high quality with a high degree of confidence because of the experimental and statistical analysis techniques utilized.

The equilibrium-diffusion limit for radiation hydrodynamics

DOE PAGES

Ferguson, J. M.; Morel, J. E.; Lowrie, R.

2017-07-27

The equilibrium-diffusion approximation (EDA) is used to describe certain radiation-hydrodynamic (RH) environments. When this is done the RH equations reduce to a simplified set of equations. The EDA can be derived by asymptotically analyzing the full set of RH equations in the equilibrium-diffusion limit. Here, we derive the EDA this way and show that it and the associated set of simplified equations are both first-order accurate with transport corrections occurring at second order. Having established the EDA’s first-order accuracy we then analyze the grey nonequilibrium-diffusion approximation and the grey Eddington approximation and show that they both preserve this first-order accuracy.more » Further, these approximations preserve the EDA’s first-order accuracy when made in either the comoving-frame (CMF) or the lab-frame (LF). And while analyzing the Eddington approximation, we found that the CMF and LF radiation-source equations are equivalent when neglecting O(β 2) terms and compared in the LF. Of course, the radiation pressures are not equivalent. It is expected that simplified physical models and numerical discretizations of the RH equations that do not preserve this first-order accuracy will not retain the correct equilibrium-diffusion solutions. As a practical example, we show that nonequilibrium-diffusion radiative-shock solutions devolve to equilibrium-diffusion solutions when the asymptotic parameter is small.« less

Reducing attenuation in exposure-response relationships by exposure modeling and grouping: the relationship between wood dust exposure and lung function.

PubMed

Teschke, Kay; Spierings, Judith; Marion, Stephen A; Demers, Paul A; Davies, Hugh W; Kennedy, Susan M

2004-12-01

In a study of wood dust exposure and lung function, we tested the effect on the exposure-response relationship of six different exposure metrics using the mean measured exposure of each subject versus the mean exposure based on various methods of grouping subjects, including job-based groups and groups based on an empirical model of the determinants of exposure. Multiple linear regression was used to examine the association between wood dust concentration and forced expiratory volume in 1s (FEV(1)), adjusting for age, sex, height, race, pediatric asthma, and smoking. Stronger point estimates of the exposure-response relationships were observed when exposures were based on increasing levels of aggregation, allowing the relationships to be found statistically significant in four of the six metrics. The strongest point estimates were found when exposures were based on the determinants of exposure model. Determinants of exposure modeling offers the potential for improvement in risk estimation equivalent to or beyond that from job-based exposure grouping.

A method for determining the weak statistical stationarity of a random process

NASA Technical Reports Server (NTRS)

Sadeh, W. Z.; Koper, C. A., Jr.

1978-01-01

A method for determining the weak statistical stationarity of a random process is presented. The core of this testing procedure consists of generating an equivalent ensemble which approximates a true ensemble. Formation of an equivalent ensemble is accomplished through segmenting a sufficiently long time history of a random process into equal, finite, and statistically independent sample records. The weak statistical stationarity is ascertained based on the time invariance of the equivalent-ensemble averages. Comparison of these averages with their corresponding time averages over a single sample record leads to a heuristic estimate of the ergodicity of a random process. Specific variance tests are introduced for evaluating the statistical independence of the sample records, the time invariance of the equivalent-ensemble autocorrelations, and the ergodicity. Examination and substantiation of these procedures were conducted utilizing turbulent velocity signals.

Case Report: Human Exposure to Dioxins from Clay

PubMed Central

Franzblau, Alfred; Hedgeman, Elizabeth; Chen, Qixuan; Lee, Shih-Yuan; Adriaens, Peter; Demond, Avery; Garabrant, David; Gillespie, Brenda; Hong, Biling; Jolliet, Olivier; Lepkowski, James; Luksemburg, William; Maier, Martha; Wenger, Yvan

2008-01-01

Context For the general population, the dominant source of exposure to dioxin-like compounds is food. As part of the University of Michigan Dioxin Exposure Study (UMDES), we measured selected polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) in serum of 946 subjects who were a representative sample of the general population in five Michigan counties. Case presentation The total toxic equivalency (TEQ; based on 2005 World Health Organization toxic equivalency factors) of serum from the index case was 211 ppt on a lipid-adjusted basis, which was the highest value observed in the UMDES study population. This subject had no apparent opportunity for exposure to dioxins, except that she had lived on property with soil contaminated with dioxins for almost 30 years, and had been a ceramics hobbyist for > 30 years. Soil from her property and clay that she used for ceramics were both contaminated with dioxins, but the congener patterns differed. Discussion The congener patterns in this subject’s serum, soil, and ceramic clay suggest strongly that the dioxin contamination in clay and not soil was the dominant source of dioxin contamination in her serum. Relevance to public health practice: It appears that ceramic clay, in particular the process of firing clay with unvented kilns, can be a significant nonfood and nonindustrial source of human exposure to dioxins among ceramics hobbyists. The extent of human exposure from ceramic clay is unclear, but it may be widespread. Further work is needed to more precisely characterize the routes of exposure. PMID:18288324

Risk of eye lens radiation exposure for members of the public.

PubMed

Chevallier, M-A; Rannou, A; Villagrasa, C; Clairand, I

2016-01-01

In 2011, the International Commission on Radiological Protection (ICRP) reviewed its recommendation concerning the equivalent dose limit for the eye lens, lowering it to 20 mSv in a year, for occupational exposure in planned exposure situations. The ICRP's statement does not contain any explicit recommendations regarding the organ dose limit for the eye lens for public exposure. For the moment, no change is proposed. But, to be coherent in the overall approach, the current equivalent limit for the public might be lowered. A similar yardstick than in the former recommendation may be used, that is to say a reduction of 10 times lower than that for occupational exposure. In this context, additional data on potential scenarios for public exposure of the eye lens are necessary. This paper, mainly based on a literature study, aims to provide, as far as possible, an exhaustive list of the situations in which members of the public can be exposed at the level of the eye lens. Once these situations have been defined, some calculations, made to assess the associated doses to the eye lens, are presented. This literature study did not reveal any current situations where members of the public would receive significant radiation doses to the eye lens. Indeed, the situations in which the dose to the eye lens might reach around 1 mSv per year for the public are extremely rare. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Personal exposure monitoring of PM2.5 in indoor and outdoor microenvironments.

PubMed

Steinle, Susanne; Reis, Stefan; Sabel, Clive E; Semple, Sean; Twigg, Marsailidh M; Braban, Christine F; Leeson, Sarah R; Heal, Mathew R; Harrison, David; Lin, Chun; Wu, Hao

2015-03-01

Adverse health effects from exposure to air pollution are a global challenge and of widespread concern. Recent high ambient concentration episodes of air pollutants in European cities highlighted the dynamic nature of human exposure and the gaps in data and knowledge about exposure patterns. In order to support health impact assessment it is essential to develop a better understanding of individual exposure pathways in people's everyday lives by taking account of all environments in which people spend time. Here we describe the development, validation and results of an exposure method applied in a study conducted in Scotland. A low-cost particle counter based on light-scattering technology - the Dylos 1700 was used. Its performance was validated in comparison with equivalent instruments (TEOM-FDMS) at two national monitoring network sites (R(2)=0.9 at a rural background site, R(2)=0.7 at an urban background site). This validation also provided two functions to convert measured PNCs into calculated particle mass concentrations for direct comparison of concentrations with equivalent monitoring instruments and air quality limit values. This study also used contextual and time-based activity data to define six microenvironments (MEs) to assess everyday exposure of individuals to short-term PM2.5 concentrations. The Dylos was combined with a GPS receiver to track movement and exposure of individuals across the MEs. Seventeen volunteers collected 35 profiles. Profiles may have a different overall duration and structure with respect to times spent in different MEs and activities undertaken. Results indicate that due to the substantial variability across and between MEs, it is essential to measure near-complete exposure pathways to allow for a comprehensive assessment of the exposure risk a person encounters on a daily basis. Taking into account the information gained through personal exposure measurements, this work demonstrates the added value of data generated by the application of low-cost monitors. Copyright © 2014. Published by Elsevier B.V.

On the existence of mosaic-skeleton approximations for discrete analogues of integral operators

NASA Astrophysics Data System (ADS)

Kashirin, A. A.; Taltykina, M. Yu.

2017-09-01

Exterior three-dimensional Dirichlet problems for the Laplace and Helmholtz equations are considered. By applying methods of potential theory, they are reduced to equivalent Fredholm boundary integral equations of the first kind, for which discrete analogues, i.e., systems of linear algebraic equations (SLAEs) are constructed. The existence of mosaic-skeleton approximations for the matrices of the indicated systems is proved. These approximations make it possible to reduce the computational complexity of an iterative solution of the SLAEs. Numerical experiments estimating the capabilities of the proposed approach are described.

A synchronous game for binary constraint systems

NASA Astrophysics Data System (ADS)

Kim, Se-Jin; Paulsen, Vern; Schafhauser, Christopher

2018-03-01

Recently, Slofstra proved that the set of quantum correlations is not closed. We prove that the set of synchronous quantum correlations is not closed, which implies his result, by giving an example of a synchronous game that has a perfect quantum approximate strategy but no perfect quantum strategy. We also exhibit a graph for which the quantum independence number and the quantum approximate independence number are different. We prove new characterisations of synchronous quantum approximate correlations and synchronous quantum spatial correlations. We solve the synchronous approximation problem of Dykema and the second author, which yields a new equivalence of Connes' embedding problem in terms of synchronous correlations.

Microeconomic analysis of military aircraft bearing restoration

NASA Technical Reports Server (NTRS)

Hein, G. F.

1976-01-01

The risk and cost of a bearing restoration by grinding program was analyzed. A microeconomic impact analysis was performed. The annual cost savings to U.S. Army aviation is approximately $950,000.00 for three engines and three transmissions. The capital value over an indefinite life is approximately ten million dollars. The annual cost savings for U.S. Air Force engines is approximately $313,000.00 with a capital value of approximately 3.1 million dollars. The program will result in the government obtaining bearings at lower costs at equivalent reliability. The bearing industry can recover lost profits during a period of reduced demand and higher costs.

An analytical method to calculate equivalent fields to irregular symmetric and asymmetric photon fields.

PubMed

Tahmasebi Birgani, Mohamad J; Chegeni, Nahid; Zabihzadeh, Mansoor; Hamzian, Nima

2014-01-01

Equivalent field is frequently used for central axis depth-dose calculations of rectangular- and irregular-shaped photon beams. As most of the proposed models to calculate the equivalent square field are dosimetry based, a simple physical-based method to calculate the equivalent square field size was used as the basis of this study. The table of the sides of the equivalent square or rectangular fields was constructed and then compared with the well-known tables by BJR and Venselaar, et al. with the average relative error percentage of 2.5 ± 2.5% and 1.5 ± 1.5%, respectively. To evaluate the accuracy of this method, the percentage depth doses (PDDs) were measured for some special irregular symmetric and asymmetric treatment fields and their equivalent squares for Siemens Primus Plus linear accelerator for both energies, 6 and 18MV. The mean relative differences of PDDs measurement for these fields and their equivalent square was approximately 1% or less. As a result, this method can be employed to calculate equivalent field not only for rectangular fields but also for any irregular symmetric or asymmetric field. © 2013 American Association of Medical Dosimetrists Published by American Association of Medical Dosimetrists All rights reserved.

Performance of Axial-Flow Supersonic Compressor on XJ-55-FF-1 Turbojet Engine. I - Preliminary Performance of Compressor. 1; Preliminary Performance of Compressor

NASA Technical Reports Server (NTRS)

Hartmann, Melvin J.; Graham, Robert C.

1949-01-01

An investigation was conducted to determine the performance characteristics of the axial-flow supersonic compressor of the XJ-55-FF-1 turbo Jet engine. The test unit consisted of a row of inlet guide vanes and a supersonic rotor; the stator vanes after the rotor were omitted. The maximum pressure ratio produced in the single stage was 2.28 at an equivalent tip speed or 1814 feet per second with an adiabatic efficiency of approximately 0.61, equivalent weight flow of 13.4 pounds per second. The maximum efficiency of 0.79 was obtained at an equivalent tip speed of 801 feet per second.

Approximating lens power.

PubMed

Kaye, Stephen B

2009-04-01

To provide a scalar measure of refractive error, based on geometric lens power through principal, orthogonal and oblique meridians, that is not limited to the paraxial and sag height approximations. A function is derived to model sections through the principal meridian of a lens, followed by rotation of the section through orthogonal and oblique meridians. Average focal length is determined using the definition for the average of a function. Average univariate power in the principal meridian (including spherical aberration), can be computed from the average of a function over the angle of incidence as determined by the parameters of the given lens, or adequately computed from an integrated series function. Average power through orthogonal and oblique meridians, can be similarly determined using the derived formulae. The widely used computation for measuring refractive error, the spherical equivalent, introduces non-constant approximations, leading to a systematic bias. The equations proposed provide a good univariate representation of average lens power and are not subject to a systematic bias. They are particularly useful for the analysis of aggregate data, correlating with biological treatment variables and for developing analyses, which require a scalar equivalent representation of refractive power.

An alternative approach for computing seismic response with accidental eccentricity

NASA Astrophysics Data System (ADS)

Fan, Xuanhua; Yin, Jiacong; Sun, Shuli; Chen, Pu

2014-09-01

Accidental eccentricity is a non-standard assumption for seismic design of tall buildings. Taking it into consideration requires reanalysis of seismic resistance, which requires either time consuming computation of natural vibration of eccentric structures or finding a static displacement solution by applying an approximated equivalent torsional moment for each eccentric case. This study proposes an alternative modal response spectrum analysis (MRSA) approach to calculate seismic responses with accidental eccentricity. The proposed approach, called the Rayleigh Ritz Projection-MRSA (RRP-MRSA), is developed based on MRSA and two strategies: (a) a RRP method to obtain a fast calculation of approximate modes of eccentric structures; and (b) an approach to assemble mass matrices of eccentric structures. The efficiency of RRP-MRSA is tested via engineering examples and compared with the standard MRSA (ST-MRSA) and one approximate method, i.e., the equivalent torsional moment hybrid MRSA (ETM-MRSA). Numerical results show that RRP-MRSA not only achieves almost the same precision as ST-MRSA, and is much better than ETM-MRSA, but is also more economical. Thus, RRP-MRSA can be in place of current accidental eccentricity computations in seismic design.

A Treatise on Equivalent-Plate Stiffnesses for Stiffened Laminated-Composite Plates and Plate-Like Lattices

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.

2011-01-01

A survey of studies conducted since 1914 on the use of equivalent-plate stiffnesses in modeling the overall, stiffness-critical response of stiffened plates and shells is presented. Two detailed, comprehensive derivations of first-approximation equivalent-plate stiffnesses are also presented that are based on the Reissner-Mindlin-type, first-order transverse-shear deformation theory for anisotropic plates. Equivalent-plate stiffness expressions, and a corresponding symbolic manipulation computer program, are also presented for several different stiffener configurations. These expressions are very general and exhibit the full range of anisotropies permitted by the Reissner-Mindlin-type, first-order transverse-shear deformation theory for anisotropic plates. The expressions presented in the present study were also compared with available, previously published results. For the most part, the previously published results are for special cases of the general expressions presented herein and are almost in complete agreement. Analysis is also presented that extends the use of the equivalent-plate stiffness expressions to sandwich plates.

Development of a direct experimental test for any violation of the equivalence principle by the weak interaction

NASA Technical Reports Server (NTRS)

Parker, P. D. M.

1981-01-01

Violation of the equivalence principle by the weak interaction is tested. Any variation of the weak interaction coupling constant with gravitational potential, i.e., a spatial variation of the fundamental constants is investigated. The level of sensitivity required for such a measurement is estimated on the basis of the size of a change in the gravitational potential which is accessible. The alpha particle spectrum is analyzed, and the counting rate was improved by a factor of approximately 100.

Improved control of medical x-ray film exposure

NASA Technical Reports Server (NTRS)

Berdahl, C. M.

1978-01-01

Exposure sensing system for light-intensified motion-picture X-ray system uses aperture or adjustable diaphragm to sample light from image region of interest. Approach, along with approximate optics, can optimize exposure sensitivity.

Generation of optimal artificial neural networks using a pattern search algorithm: application to approximation of chemical systems.

PubMed

Ihme, Matthias; Marsden, Alison L; Pitsch, Heinz

2008-02-01

A pattern search optimization method is applied to the generation of optimal artificial neural networks (ANNs). Optimization is performed using a mixed variable extension to the generalized pattern search method. This method offers the advantage that categorical variables, such as neural transfer functions and nodal connectivities, can be used as parameters in optimization. When used together with a surrogate, the resulting algorithm is highly efficient for expensive objective functions. Results demonstrate the effectiveness of this method in optimizing an ANN for the number of neurons, the type of transfer function, and the connectivity among neurons. The optimization method is applied to a chemistry approximation of practical relevance. In this application, temperature and a chemical source term are approximated as functions of two independent parameters using optimal ANNs. Comparison of the performance of optimal ANNs with conventional tabulation methods demonstrates equivalent accuracy by considerable savings in memory storage. The architecture of the optimal ANN for the approximation of the chemical source term consists of a fully connected feedforward network having four nonlinear hidden layers and 117 synaptic weights. An equivalent representation of the chemical source term using tabulation techniques would require a 500 x 500 grid point discretization of the parameter space.

Quantification of ETS exposure in hospitality workers who have never smoked

PubMed Central

2010-01-01

Background Environmental Tobacco Smoke (ETS) was classified as human carcinogen (K1) by the German Research Council in 1998. According to epidemiological studies, the relative risk especially for lung cancer might be twice as high in persons who have never smoked but who are in the highest exposure category, for example hospitality workers. In order to implement these results in the German regulations on occupational illnesses, a valid method is needed to retrospectively assess the cumulative ETS exposure in the hospitality environment. Methods A literature-based review was carried out to locate a method that can be used for the German hospitality sector. Studies assessing ETS exposure using biological markers (for example urinary cotinine, DNA adducts) or questionnaires were excluded. Biological markers are not considered relevant as they assess exposure only over the last hours, weeks or months. Self-reported exposure based on questionnaires also does not seem adequate for medico-legal purposes. Therefore, retrospective exposure assessment should be based on mathematical models to approximate past exposure. Results For this purpose a validated model developed by Repace and Lowrey was considered appropriate. It offers the possibility of retrospectively assessing exposure with existing parameters (such as environmental dimensions, average number of smokers, ventilation characteristics and duration of exposure). The relative risk of lung cancer can then be estimated based on the individual cumulative exposure of the worker. Conclusion In conclusion, having adapted it to the German hospitality sector, an existing mathematical model appears to be capable of approximating the cumulative exposure. However, the level of uncertainty of these approximations has to be taken into account, especially for diseases with a long latency period such as lung cancer. PMID:20704719

Quantification of ETS exposure in hospitality workers who have never smoked.

PubMed

Kolb, Stefanie; Brückner, Ulrike; Nowak, Dennis; Radon, Katja

2010-08-12

Environmental Tobacco Smoke (ETS) was classified as human carcinogen (K1) by the German Research Council in 1998. According to epidemiological studies, the relative risk especially for lung cancer might be twice as high in persons who have never smoked but who are in the highest exposure category, for example hospitality workers. In order to implement these results in the German regulations on occupational illnesses, a valid method is needed to retrospectively assess the cumulative ETS exposure in the hospitality environment. A literature-based review was carried out to locate a method that can be used for the German hospitality sector. Studies assessing ETS exposure using biological markers (for example urinary cotinine, DNA adducts) or questionnaires were excluded. Biological markers are not considered relevant as they assess exposure only over the last hours, weeks or months. Self-reported exposure based on questionnaires also does not seem adequate for medico-legal purposes. Therefore, retrospective exposure assessment should be based on mathematical models to approximate past exposure. For this purpose a validated model developed by Repace and Lowrey was considered appropriate. It offers the possibility of retrospectively assessing exposure with existing parameters (such as environmental dimensions, average number of smokers, ventilation characteristics and duration of exposure). The relative risk of lung cancer can then be estimated based on the individual cumulative exposure of the worker. In conclusion, having adapted it to the German hospitality sector, an existing mathematical model appears to be capable of approximating the cumulative exposure. However, the level of uncertainty of these approximations has to be taken into account, especially for diseases with a long latency period such as lung cancer.

Uptake, distribution and depuration of paralytic shellfish toxins from Alexandrium minutum in Australian greenlip abalone, Haliotis laevigata.

PubMed

Dowsett, Natalie; Hallegraeff, Gustaaf; van Ruth, Paul; van Ginkel, Roel; McNabb, Paul; Hay, Brenda; O'Connor, Wayne; Kiermeier, Andreas; Deveney, Marty; McLeod, Catherine

2011-07-01

Farmed greenlip abalone Haliotis laevigata were fed commercial seaweed-based food pellets or feed pellets supplemented with 8 × 10⁵ Alexandrium minutum dinoflagellate cells g⁻¹ (containing 12 ± 3.0 μg STX-equivalent 100 g⁻¹, which was mainly GTX-1,4) every second day for 50 days. Exposure of abalone to PST supplemented feed for 50 days did not affect behaviour or survival but saw accumulation of up to 1.6 μg STX-equivalent 100 g⁻¹ in the abalone foot tissue (muscle, mouth without oesophagus and epipodial fringe), which is ∼50 times lower than the maximum permissible limit (80 μg 100 g⁻¹ tissue) for PSTs in molluscan shellfish. The PST levels in the foot were reduced to 0.48 μg STX-equivalent 100 g⁻¹ after scrubbing and removal of the pigment surrounding the epithelium of the epipodial fringe (confirmed by both HPLC and LC-MS/MS). Thus, scrubbing the epipodial fringe, a common procedure during commercial abalone canning, reduced PST levels by ∼70%. Only trace levels of PSTs were detected in the viscera (stomach, gut, heart, gonad, gills and mantle) of the abalone. A toxin reduction of approximately 73% was observed in STX-contaminated abalone held in clean water and fed uncontaminated food over 50 days. The low level of PST uptake when abalone were exposed to high numbers of A. minutum cells over a prolonged period may indicate a low risk of PSP poisoning to humans from the consumption of H. laevigata that has been exposed to a bloom of potentially toxic A. minutum in Australia. Further research is required to establish if non-dietary accumulation can result in significant levels of PSTs in abalone. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

FLUKA simulation of TEPC response to cosmic radiation.

PubMed

Beck, P; Ferrari, A; Pelliccioni, M; Rollet, S; Villari, R

2005-01-01

The aircrew exposure to cosmic radiation can be assessed by calculation with codes validated by measurements. However, the relationship between doses in the free atmosphere, as calculated by the codes and from results of measurements performed within the aircraft, is still unclear. The response of a tissue-equivalent proportional counter (TEPC) has already been simulated successfully by the Monte Carlo transport code FLUKA. Absorbed dose rate and ambient dose equivalent rate distributions as functions of lineal energy have been simulated for several reference sources and mixed radiation fields. The agreement between simulation and measurements has been well demonstrated. In order to evaluate the influence of aircraft structures on aircrew exposure assessment, the response of TEPC in the free atmosphere and on-board is now simulated. The calculated results are discussed and compared with other calculations and measurements.

Measurements and simulations of the radiation exposure to aircraft crew workplaces due to cosmic radiation in the atmosphere.

PubMed

Beck, P; Latocha, M; Dorman, L; Pelliccioni, M; Rollet, S

2007-01-01

As required by the European Directive 96/29/Euratom, radiation exposure due to natural ionizing radiation has to be taken into account at workplaces if the effective dose could become more than 1 mSv per year. An example of workers concerned by this directive is aircraft crew due to cosmic radiation exposure in the atmosphere. Extensive measurement campaigns on board aircrafts have been carried out to assess ambient dose equivalent. A consortium of European dosimetry institutes within EURADOS WG5 summarized experimental data and results of calculations, together with detailed descriptions of the methods for measurements and calculations. The radiation protection quantity of interest is the effective dose, E (ISO). The comparison of results by measurements and calculations is done in terms of the operational quantity ambient dose equivalent, H(10). This paper gives an overview of the EURADOS Aircraft Crew In-Flight Database and it presents a new empirical model describing fitting functions for this data. Furthermore, it describes numerical simulations performed with the Monte Carlo code FLUKA-2005 using an updated version of the cosmic radiation primary spectra. The ratio between ambient dose equivalent and effective dose at commercial flight altitudes, calculated with FLUKA-2005, is discussed. Finally, it presents the aviation dosimetry model AVIDOS based on FLUKA-2005 simulations for routine dose assessment. The code has been developed by Austrian Research Centers (ARC) for the public usage (http://avidos.healthphysics.at).

Comparison of lead attenuation and lead hardening equivalence of materials used in respect of diagnostic X-ray shielding.

PubMed

Okunade, Akintunde Akangbe

2002-12-01

Present interest is in the shielding of diagnostic X-ray units. Numerical comparison has been made of the attenuation and hardening properties of lead and some particular alternative materials: steel, plate glass and gypsum wallboard. Results show, for particular choices of thickness, that lead and steel can be made to provide closely similar attenuation and spectral hardening, values of lead attenuation equivalent (LAE) and lead hardening equivalent (LHE) thicknesses being nearly the same. Significant differences in the attenuation and hardening properties of lead are found in comparison with plate glass and gypsum wallboard. LAE produces better matching of exposure for lead-plate glass and lead-gypsum wallboard than LHE.

Method for extracting long-equivalent wavelength interferometric information

NASA Technical Reports Server (NTRS)

Hochberg, Eric B. (Inventor)

1991-01-01

A process for extracting long-equivalent wavelength interferometric information from a two-wavelength polychromatic or achromatic interferometer. The process comprises the steps of simultaneously recording a non-linear sum of two different frequency visible light interferograms on a high resolution film and then placing the developed film in an optical train for Fourier transformation, low pass spatial filtering and inverse transformation of the film image to produce low spatial frequency fringes corresponding to a long-equivalent wavelength interferogram. The recorded non-linear sum irradiance derived from the two-wavelength interferometer is obtained by controlling the exposure so that the average interferogram irradiance is set at either the noise level threshold or the saturation level threshold of the film.

A review of Arbuckle Group strata in Kansas from a sedimentologic perspective: Insights for future research from past and recent studies

USGS Publications Warehouse

Franseen, E.K.

2000-01-01

Arbuckle Group and equivalent-age rocks (Cambrian and Lower Ordovician) represent an important record of sediment deposition in the history of the North American continent and they contain important accumulations of hydrocarbons (oil and gas) and base metal deposits. This is true for Kansas as well where Arbuckle strata account for approximately 40% of the volume of produced petroleum and known reserves. However, in comparison to their counterparts in other areas, such as the Ellenburger and Knox, Arbuckle rocks in Kansas remain relatively understudied, especially with respect to sedimentology and diagenesis. The Arbuckle is present in the subsurface in most of Kansas and is absent only in areas of northeastern and northwestern Kansas, and over ancient uplifts and buried Precambrian highs. Arbuckle rocks thicken from north to south and are up to 1,390 feet in the southeastern corner of Kansas. Arbuckle Group and equivalent-age rocks from Kansas and surrounding areas are similar, consisting of platform deposits dominated by ramp-type subtidal to peritidal carbonates (mostly dolomitized) which can be subdivided into cycles, less than 0.5 m to 40 m thick, based on facies type and depositional patterns. Recent studies from central Kansas show that major depositional facies consist of coarse-grained packstones/ grainstones, fine-grained packstones/wackestones/mudstones, stromatolites-thrombolites, intraclastic conglomerate and breccia, and shale. In addition, secondary features include dolomitization, breccia, fracture, and conglomerate related to early subaerial exposure and later karst, burial or structural processes, silicification, and local mineralization. Arbuckle and equivalent strata in the Midcontinent were affected by prolonged subaerial exposure that began immediately after Arbuckle deposition, forming the sub-Tippecanoe to sub-Absaroka unconformity. Favorable reservoir qualities generally are thought to be related directly to basement structural elements and karstic features from the post-Arbuckle subaerial exposure event. Although most production in Kansas is from the top of the Arbuckle, some early and recent studies indicate that the Arbuckle is not a simple homogeneous reservoir, that complex vertical and lateral heterogeneities exist including both nonporous and porous horizons in the formation, and that high probability exist of locating additional oil with improved reservoir characterization. Although fracture and vuggy porosity contribute importantly to the production of Arbuckle strata, recent observations indicate a significant amount of porosity (about 50%) in many cores is controlled by depositional facies and dolomitization. Studies of Arbuckle and equivalent-age strata from other areas indicate that Arbuckle strata and diagenetic processes are complex and that porosity/permeability patterns are related to a number of processes. These studies underscore the importance of continued study of Arbuckle rocks in Kansas for improved reservoir characterization. Ongoing and future geologic studies of Arbuckle rocks in Kansas are being directed toward: (1) Continued sedimentologic, stratigraphic, and sequence stratigraphic analyses incorporating core, well log, and seismic data; (2) petrophysical studies. Initial studies indicate that core plug petrophysical properties are controlled by matrix grain size and that upscalling from plug to whole-core and drill-stem test data can identify and quantify the relative contribution of karstic, fracture and matrix porosity and permeability: (3) Regional and local structural analyses and mapping of the upper Arbuckle surface to provide more details on the contribution of structural features and karst paleogeomorphology to reservoir character; and (4) diagenetic and geochemical studies focusing especially on the timing of, and processes associated with, dolomitization and karstification events and their contributions to creating or occluding porosity.

Analyser-based mammography using single-image reconstruction.

PubMed

Briedis, Dahliyani; Siu, Karen K W; Paganin, David M; Pavlov, Konstantin M; Lewis, Rob A

2005-08-07

We implement an algorithm that is able to decode a single analyser-based x-ray phase-contrast image of a sample, converting it into an equivalent conventional absorption-contrast radiograph. The algorithm assumes the projection approximation for x-ray propagation in a single-material object embedded in a substrate of approximately uniform thickness. Unlike the phase-contrast images, which have both directional bias and a bias towards edges present in the sample, the reconstructed images are directly interpretable in terms of the projected absorption coefficient of the sample. The technique was applied to a Leeds TOR[MAM] phantom, which is designed to test mammogram quality by the inclusion of simulated microcalcifications, filaments and circular discs. This phantom was imaged at varying doses using three modalities: analyser-based synchrotron phase-contrast images converted to equivalent absorption radiographs using our algorithm, slot-scanned synchrotron imaging and imaging using a conventional mammography unit. Features in the resulting images were then assigned a quality score by volunteers. The single-image reconstruction method achieved higher scores at equivalent and lower doses than the conventional mammography images, but no improvement of visualization of the simulated microcalcifications, and some degradation in image quality at reduced doses for filament features.

Risk equivalent of exposure versus dose of radiation

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

Bond, V.P.

This report describes a risk analysis study of low-dose irradiation and the resulting biological effects on a cell. The author describes fundamental differences between the effects of high-level exposure (HLE) and low-level exposure (LLE). He stresses that the concept of absorbed dose to an organ is not a dose but a level of effect produced by a particular number of particles. He discusses the confusion between a linear-proportional representation of dose limits and a threshold-curvilinear representation, suggesting that a LLE is a composite of both systems. (TEM)

The risk equivalent of an exposure to-, versus a dose of radiation

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

Bond, V.P.

The long-term potential carcinogenic effects of low-level exposure (LLE) are addressed. The principal point discussed is linear, no-threshold dose-response curve. That the linear no-threshold, or proportional relationship is widely used is seen in the way in which the values for cancer risk coefficients are expressed - in terms of new cases, per million persons exposed, per year, per unit exposure or dose. This implies that the underlying relationship is proportional, i.e., ''linear, without threshold''. 12 refs., 9 figs., 1 tab.

Influence of a visual display and frequency of whole-body angular oscillation on incidence of motion sickness.

PubMed

Guedry, F E; Benson, A J; Moore, H J

1982-06-01

Visual search within a head-fixed display consisting of a 12 X 12 digit matrix is degraded by whole-body angular oscillation at 0.02 Hz (+/- 155 degrees/s peak velocity), and signs and symptoms of motion sickness are prominent in a number of individuals within a 5-min exposure. Exposure to 2.5 Hz (+/- 20 degrees/s peak velocity) produces equivalent degradation of the visual search task, but does not produce signs and symptoms of motion sickness within a 5-min exposure.

Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

NASA Astrophysics Data System (ADS)

Singh, Vishwanath P.; Badiger, N. M.

2014-11-01

Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

What Employees Need (and Want) to Hear When Justifying the Suspension of a Regulated Metals Plan for the Processing of Drums Containing Metal Turnings

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

Todd Potts, T.; Hylko, J.M.

2008-07-01

A Regulated Metals Plan (RMP) was implemented for outdoor work activities involving the removal and disposition of approximately 4,000 deteriorated waste drums containing 236 metric tonnes (260 tons) of lead turnings from various, unspecified machine shop facilities at the Paducah Gaseous Diffusion Plant. Until exposure monitoring could prove otherwise, the work area established for processing the drums was conservatively defined as a Lead Regulated Area (LRA) subject to the Occupational Safety and Health Administration's Lead Standard found in Title 29 of the Code of Federal Regulations, Part 1910.1025. The vast majority of the analytical results for the industrial hygiene breathingmore » zone samples collected and tested for arsenic, beryllium, cadmium, chromium, lead, nickel, selenium, silver, and thallium using the National Institute for Occupational Safety and Health's analytical method 7300 were equivalent to the laboratory detection limits for each analyte. All results were less than 6% of their respective Permissible Exposure Limits (PEL), except for one nickel result that was approximately 17% of its PEL. The results provided justification to eventually down-post the LRA to existing employee protection requirements. In addition to removing the deteriorated drums and accompanying debris, the success of this project was quantified in terms of zero recordable injuries. The primary contributor in achieving this success was the sharing and communication of information between management, safety, and the field teams. Specifically, this was what the employees needed (and wanted) to hear when justifying the suspension of the RMP for the processing of drums containing metal turnings. Daily briefings on the status of the project and field monitoring results were just as important as maintaining budget and schedule milestones. Also, the Environmental, Safety and Health organization maintained its presence by continuing to monitor evolving field conditions to ensure the effectiveness of its plans and procedures. (authors)« less

Mechanism of Headward Fluid Shift During Exposure To Microgravity

NASA Technical Reports Server (NTRS)

Hargens, Alan R.; Parazynski, Scott E.; Watenpaugh, Donald E.; Aratow, Michael; Murthy, Gita; Kawai, Yasuaki

1994-01-01

A prominent feature of early cardiovascular adaptation to the microgravity of space flight is a shift of blood and tissue fluid from the lower body to the upper body. Symptoms of this fluid shift include facial edema, nasal congestion, and headache. Normally on Earth, the human body is exposed to hydrostatic (gravitational) blood pressure gradients during upright posture. In this posture, mean arterial pressures at head, heart, and foot levels are approximately 70, 100, and 200 mm Hg, respectively. Theoretically, all hydrostatic pressures within arteries and veins are lost during exposure to microgravity so that mean arterial pressure in all regions of the body is uniform and approximately equal to that at heart level (100 mm Hg). Acute studies of 60 head-down tilt (simulated microgravity on Earth) indicate that facial edema is caused by: 1) elevation of capillary blood pressure from 28 to 34 mm Hg, 2) reduction of blood colloid osmotic pressure 22 to 18 mm Hg, and 3) 50% increase of blood perfusion in tissues of the head. Furthermore, as compared to microvasculature in the feet, microvessels of the head have a low capacity to constrict and diminish local perfusion. Elevation of blood and tissue fluid pressures/flow in the head may also explain the higher headward bone density associated with long-term head-down tilt. These mechanistic studies of head-down tilt, along with a better understanding of the relative stresses involved with upright posture and lower body negative pressure, have facilitated development of physiologic countermeasures to maintain astronaut health during microgravity. Presently no exercise hardware is available to provide a blood pressure gradient from head to feet in space. However, recent studies in our laboratory suggest that treadmill exercise within lower body negative pressure provides equivalent or greater physiologic stress as compared to similar upright exercise on Earth.

Associations of Pre-transplant Prescription Narcotic Use with Clinical Complications after Kidney Transplantation

PubMed Central

Lentine, Krista L.; Lam, Ngan N.; Xiao, Huiling; Tuttle-Newhall, Janet E.; Axelrod, David; Brennan, Daniel C.; Dharnidharka, Vikas R.; Yuan, Hui; Nazzal, Mustafa; Zheng, Jie; Schnitzler, Mark A.

2015-01-01

Background Associations of narcotic use before kidney transplantation with post-transplant clinical outcomes are not well described. Methods We examined integrated national transplant registry, pharmacy records, and Medicare billing claims to follow 16,322 kidney transplant recipients, of whom 28.3% filled a narcotic prescription in the year before transplantation. Opioid analgesic fills were normalized to morphine equivalents (ME) and expressed as mg/kg exposures (approximate quartiles: 0.1– 1.7, 1.8–5.4, 5.5–23.7, and ≥23.8 mg/kg, respectively). Post-transplant cardiovascular, respiratory, neurological, accidents, substance abuse, and non-compliance events were identified using diagnosis codes on Medicare billing claims. Adjusted associations of ME level with post-transplant complications were quantified by multivariate Cox regression. Results The incidence of complications at 3 years post-transplant among those with the highest pre-transplant ME exposure compared to no use included: ventricular arrhythmias, 1.1% vs. 0.2% (p<0.001); cardiac arrest, 4.7% vs. 2.7% (p<0.05); hypotension, 14% vs. 8% (p<0.0001); hypercapnia, 1.6% vs. 0.9% (p<0.05); mental status changes, 5.3% vs. 2.7% (p<0.001); drug abuse/dependence, 7.0% vs. 1.7% (p<0.0001); alcohol abuse, 1.8% vs. 0.6% (p=0.0001); accidents, 0.9% vs. 0.3% (p<0.05); and non-compliance, 3.5% vs. 2.3% (p<0.05). In multivariate analyses, transplant recipients with the highest level of pre-transplant narcotic use had approximately 2-to-4-times the risks of post-transplant ventricular arrhythmias, mental status changes, drug abuse, alcohol abuse, and accidents compared with non-users, and 35% to 45% higher risks of cardiac arrest and hypotension. Conclusion Although associations may reflect underlying conditions or behaviors, high-level prescription narcotic use before kidney transplantation predicts increased risk of clinical complications after transplantation. PMID:25832723

Depth dependence of absorbed dose, dose equivalent and linear energy transfer spectra of galactic and trapped particles in polyethylene and comparison with calculations of models

NASA Technical Reports Server (NTRS)

Badhwar, G. D.; Cucinotta, F. A.; Wilson, J. W. (Principal Investigator)

1998-01-01

A matched set of five tissue-equivalent proportional counters (TEPCs), embedded at the centers of 0 (bare), 3, 5, 8 and 12-inch-diameter polyethylene spheres, were flown on the Shuttle flight STS-81 (inclination 51.65 degrees, altitude approximately 400 km). The data obtained were separated into contributions from trapped protons and galactic cosmic radiation (GCR). From the measured linear energy transfer (LET) spectra, the absorbed dose and dose-equivalent rates were calculated. The results were compared to calculations made with the radiation transport model HZETRN/NUCFRG2, using the GCR free-space spectra, orbit-averaged geomagnetic transmission function and Shuttle shielding distributions. The comparison shows that the model fits the dose rates to a root mean square (rms) error of 5%, and dose-equivalent rates to an rms error of 10%. Fairly good agreement between the LET spectra was found; however, differences are seen at both low and high LET. These differences can be understood as due to the combined effects of chord-length variation and detector response function. These results rule out a number of radiation transport/nuclear fragmentation models. Similar comparisons of trapped-proton dose rates were made between calculations made with the proton transport model BRYNTRN using the AP-8 MIN trapped-proton model and Shuttle shielding distributions. The predictions of absorbed dose and dose-equivalent rates are fairly good. However, the prediction of the LET spectra below approximately 30 keV/microm shows the need to improve the AP-8 model. These results have strong implications for shielding requirements for an interplanetary manned mission.

Acute Mountain Sickness at 4500 m is not Altered by Repeated Eight-Hour Exposures to 3200-3550 m Normobaric Hypoxic Equivalent,

DTIC Science & Technology

1987-09-10

subject had his own numbered device, which was disassembled, washed and disinfected ( benzalkonium chloride , 1:1000 v/v) each evening. 4 Subjects...fluctuations throughout the 10-day period after the reduction in altitude equivalent which occurred during day I, either in the group mean values (shown) or...significant reduction in hemoglobin concentration in the control group over the sea level treatment period, with a concomitant, but non-significant

Utilising shade to optimize UV exposure for vitamin D

NASA Astrophysics Data System (ADS)

Turnbull, D. J.; Parisi, A. V.

2008-06-01

Numerous studies have stated that humans need to utilise full sun radiation, at certain times of the day, to assist the body in synthesising the required levels of vitamin D3. The time needed to be spent in the full sun depends on a number of factors, for example, age, skin type, latitude, solar zenith angle. Current Australian guidelines suggest exposure to approximately 1/6 to 1/3 of a minimum erythemal dose (MED), depending on age, would be appropriate to provide adequate vitamin D3 levels. The aim of the study was to determine the exposure times to diffuse solar UV to receive exposures of 1/6 and 1/3 MED for a changing solar zenith angle in order to assess the possible role that diffuse UV (scattered radiation) may play in vitamin D3 effective UV exposures (UVD3). Diffuse and global erythemal UV measurements were conducted at five minute intervals over a twelve month period for a solar zenith angle range of 4° to 80° at a latitude of 27.6° S. For a diffuse UV exposure of 1/3 MED, solar zenith angles smaller than approximately 50° can be utilised for exposure times of less than 10 min. Spectral measurements showed that, for a solar zenith angle of 40°, the UVA (315-400 nm) in the diffuse component of the solar UV is reduced by approximately 62% compared to the UVA in the global UV, whereas UVD3 wavelengths are only reduced by approximately 43%. At certain latitudes, diffuse UV under shade may play an important role in providing the human body with adequate levels of UVD3 (290-315 nm) radiation without experiencing the high levels of UVA observed in full sun.

Stress intensity factors for long, deep surface flaws in plates under extensional fields

NASA Technical Reports Server (NTRS)

Harms, A. E.; Smith, C. W.

1973-01-01

Using a singular solution for a part circular crack, a Taylor Series Correction Method (TSCM) was verified for extracting stress intensity factors from photoelastic data. Photoelastic experiments were then conducted on plates with part circular and flat bottomed cracks for flaw depth to thickness ratios of 0.25, 0.50 and 0.75 and for equivalent flaw depth to equivalent ellipse length values ranging from 0.066 to 0.319. Experimental results agreed well with the Smith theory but indicated that the use of the ''equivalent'' semi-elliptical flaw results was not valid for a/2c less than 0.20. Best overall agreement for the moderate (a/t approximately 0.5) to deep flaws (a/t approximatelly 0.75) and a/2c greater than 0.15 was found with a semi-empirical theory, when compared on the basis of equivalent flaw depth and area.

Characterization of Different Microbubbles in Assisting Focused Ultrasound-Induced Blood-Brain Barrier Opening

NASA Astrophysics Data System (ADS)

Wu, Sheng-Kai; Chu, Po-Chun; Chai, Wen-Yen; Kang, Shih-Tsung; Tsai, Chih-Hung; Fan, Ching-Hsiang; Yeh, Chih-Kuang; Liu, Hao-Li

2017-04-01

Microbubbles (MBs) serve as a critical catalyst to amplify local cavitation in CNS capillary lumen to facilitate focused ultrasound (FUS) to transiently open the blood-brain barrier (BBB). However, limited understanding is available regarding the effect of different microbubbles to induce BBB opening. The aim of this study is to characterize different MBs on their effect in FUS-induced BBB opening. Three MBs, SonoVue, Definity, and USphere, were tested, with 0.4-MHz FUS exposure at 0.62-1.38 of mechanical index (MI) on rats. Evans blue, dynamic contrast-enhanced (DCE) MRI and small-animal ultrasound imaging were used as surrogates to allow molecule-penetrated quantification, BBB-opened observation, and MBs circulation/persistence. Cavitation activity was measured via the passive cavitation detection (PCD) setup to correlate with the exposure level and the histological effect. Under given and identical MB concentrations, the three MBs induced similar and equivalent BBB-opening effects and persistence. In addition, a treatment paradigm by adapting exposure time is proposed to compensate MB decay to retain the persistence of BBB-opening efficiency in multiple FUS exposures. The results potentially improve understanding of the equivalence among MBs in focused ultrasound CNS drug delivery, and provide an effective strategy for securing persistence in this treatment modality.

Dioxin Exposure and Age of Pubertal Onset among Russian Boys

PubMed Central

Lee, Mary M.; Williams, Paige L.; Sergeyev, Oleg; Burns, Jane S.; Patterson, Donald G.; Turner, Wayman E.; Needham, Larry L.; Altshul, Larisa; Revich, Boris; Hauser, Russ

2011-01-01

Background: Animal data demonstrate associations of dioxin, furan, and polychlorinated biphenyl (PCB) exposures with altered male gonadal maturation. It is unclear whether these associations apply to human populations. Objectives: We investigated the association of dioxins, furans, PCBs, and corresponding toxic equivalent (TEQ) concentrations with pubertal onset among boys in a dioxin-contaminated region. Methods: Between 2003 and 2005, 499 boys 8–9 years of age were enrolled in a longitudinal study in Chapaevsk, Russia. Pubertal onset [stage 2 or higher for genitalia (G2+) or testicular volume (TV) > 3 mL] was assessed annually between ages 8 and 12 years. Serum levels at enrollment were analyzed by the Centers for Disease Control and Prevention, Atlanta, Georgia, USA. We used Cox proportional hazards models to assess age at pubertal onset as a function of exposure adjusted for potential confounders. We conducted sensitivity analyses excluding boys with pubertal onset at enrollment. Results: The median (range) total serum TEQ concentration was 21 (4–175) pg/g lipid, approximately three times higher than values in European children. At enrollment, boys were generally healthy and normal weight (mean body mass index, 15.9 kg/m2), with 30% having entered puberty by G2+ and 14% by TV criteria. Higher dioxin TEQs were associated with later pubertal onset by TV (hazard ratio = 0.68, 95% confidence interval, 0.49–0.95 for the highest compared with the lowest quartile). Similar associations were observed for 2,3,7,8-tetrachlorodibenzo-p-dioxin and dioxin concentrations for TV but not G2+. Results were robust to sensitivity analyses. Conclusions: Findings support an association of higher peripubertal serum dioxin TEQs and concentrations with later male pubertal onset reflected in delayed testicular maturation. PMID:21527364

Concentrations and spatial patterns of organic contaminants in tree swallow (Tachycineta bicolor) eggs at United States and binational Great Lakes Areas of Concern, 2010–2015

USGS Publications Warehouse

Custer, Christine M.; Custer, Thomas W.; Dummer, Paul; Goldberg, Diana R.; Franson, J. Christian

2016-01-01

Tree swallows, Tachycineta bicolor, were sampled across the Great Lakes basin in 2010 through 2015 to provide a system-wide assessment of current exposure to organic contaminants. The results provide information identified as critical by regulators to assess the “bird or animal deformity or reproductive problems” beneficial use impairment. Eggs were collected from 69 sites across all 5 Great Lakes, including 27 Areas of Concern (AOCs), some with multiple sites, and 10 sites not listed as an AOC. Concentrations of organic contaminants in eggs were quantified and compared with background and reproductive effect thresholds. Approximately 30% of AOCs had geometric mean concentrations of total polychlorinated biphenyls (PCBs) at or below average background exposure (0.34 μg/g wet wt). Exposure to polybrominated diphenyl ethers (PBDEs) was minimal, and only 3 of 27 AOCs and 1 non-AOC had geometric mean concentrations that exceeded background for tree swallows (96 ng/g wet wt). Concentrations of both PCBs and PBDEs were 10 to 20 times below the lower limit associated with impaired hatching success. In contrast, geometric mean concentrations of polychlorinated dibenzo-p-dioxin and furan (PCDD-F) toxic equivalents (TEQs) at the Saginaw River and Bay AOC and Midland, Michigan, USA (a non-AOC site), exceeded the lower limit for hatching effects (181 pg/g PCDD-F TEQs). The rest of the sites had geometric mean concentrations of PCDD-F TEQs below background levels (87 pg/g PCDD-F TEQs). Other organic contaminants, including p,p′-dichlorodiphenyldichloroethylene, mirex, heptachlor, and chlordane, were at or below background or adverse effect concentrations.

Effects of high-voltage transmission lines on honey bees

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

Greenberg, B.; Bindokas, V.P.

1981-04-01

Data are reported on the effect of hive height and current distribution on honey bees hived under a 765 kV line (E-field ca. 7 kV/m). Hive height was standardized with adjustable collectors to 1 meter (59 ..mu..A total hive current) or 1.5 meter (85 ..mu..A) equivalents; controls were shielded. A 1.5 meter group with completely painted supers was included. After 8 or 16 weeks of exposure there was no effect on honey moisture content or weight of young workers in any group. Worker capped brood was not affected in 1 m hives but declined significantly in 1.5 m hives aftermore » 4 weeks of exposure and this was associated with queen loss, abnormal queen cell production, and colony failure. Weight gain was depressed in all hives after 2 weeks of exposure and was dose related, with the taller hives more severely affected. Only the exposed hives propolized entrances but the amount and time of onset were not dose related. The 1.5 m hives with painted interiors behaved like the 1 m hives with unpainted interiors in all respects, although their total hive current approximated the other group of 1.5 m hives. Reversal of treatments at midseason resulted in reversal of colony behavior, manifested most clearly with respect to hive weight, less with respect to brood. When first exposed, colonies exhibit pronounced but transient elevations in hive temperature. Bio-effects were more severe during the first period when hives had fewer bees. Total hive current was greater in wet than in dry periods. All these factors influence observed bioeffects.« less

A comparative study of space radiation organ doses and associated cancer risks using PHITS and HZETRN.

PubMed

Bahadori, Amir A; Sato, Tatsuhiko; Slaba, Tony C; Shavers, Mark R; Semones, Edward J; Van Baalen, Mary; Bolch, Wesley E

2013-10-21

NASA currently uses one-dimensional deterministic transport to generate values of the organ dose equivalent needed to calculate stochastic radiation risk following crew space exposures. In this study, organ absorbed doses and dose equivalents are calculated for 50th percentile male and female astronaut phantoms using both the NASA High Charge and Energy Transport Code to perform one-dimensional deterministic transport and the Particle and Heavy Ion Transport Code System to perform three-dimensional Monte Carlo transport. Two measures of radiation risk, effective dose and risk of exposure-induced death (REID) are calculated using the organ dose equivalents resulting from the two methods of radiation transport. For the space radiation environments and simplified shielding configurations considered, small differences (<8%) in the effective dose and REID are found. However, for the galactic cosmic ray (GCR) boundary condition, compensating errors are observed, indicating that comparisons between the integral measurements of complex radiation environments and code calculations can be misleading. Code-to-code benchmarks allow for the comparison of differential quantities, such as secondary particle differential fluence, to provide insight into differences observed in integral quantities for particular components of the GCR spectrum.

A comparative study of space radiation organ doses and associated cancer risks using PHITS and HZETRN

NASA Astrophysics Data System (ADS)

Bahadori, Amir A.; Sato, Tatsuhiko; Slaba, Tony C.; Shavers, Mark R.; Semones, Edward J.; Van Baalen, Mary; Bolch, Wesley E.

2013-10-01

NASA currently uses one-dimensional deterministic transport to generate values of the organ dose equivalent needed to calculate stochastic radiation risk following crew space exposures. In this study, organ absorbed doses and dose equivalents are calculated for 50th percentile male and female astronaut phantoms using both the NASA High Charge and Energy Transport Code to perform one-dimensional deterministic transport and the Particle and Heavy Ion Transport Code System to perform three-dimensional Monte Carlo transport. Two measures of radiation risk, effective dose and risk of exposure-induced death (REID) are calculated using the organ dose equivalents resulting from the two methods of radiation transport. For the space radiation environments and simplified shielding configurations considered, small differences (<8%) in the effective dose and REID are found. However, for the galactic cosmic ray (GCR) boundary condition, compensating errors are observed, indicating that comparisons between the integral measurements of complex radiation environments and code calculations can be misleading. Code-to-code benchmarks allow for the comparison of differential quantities, such as secondary particle differential fluence, to provide insight into differences observed in integral quantities for particular components of the GCR spectrum.

Physiological determinants of human acute hypoxia tolerance.

DOT National Transportation Integrated Search

2013-11-01

AbstractIntroduction. We investigated possible physiological determinants of variability in hypoxia tolerance in subjects given a 5-minute normobaric exposure to 25,000 ft equivalent. Physiological tolerance to hypoxia was defined as the magnitude of...

Real-time deblurring of handshake blurred images on smartphones

NASA Astrophysics Data System (ADS)

Pourreza-Shahri, Reza; Chang, Chih-Hsiang; Kehtarnavaz, Nasser

2015-02-01

This paper discusses an Android app for the purpose of removing blur that is introduced as a result of handshakes when taking images via a smartphone. This algorithm utilizes two images to achieve deblurring in a computationally efficient manner without suffering from artifacts associated with deconvolution deblurring algorithms. The first image is the normal or auto-exposure image and the second image is a short-exposure image that is automatically captured immediately before or after the auto-exposure image is taken. A low rank approximation image is obtained by applying singular value decomposition to the auto-exposure image which may appear blurred due to handshakes. This approximation image does not suffer from blurring while incorporating the image brightness and contrast information. The eigenvalues extracted from the low rank approximation image are then combined with those from the shortexposure image. It is shown that this deblurring app is computationally more efficient than the adaptive tonal correction algorithm which was previously developed for the same purpose.

Assimilation of elements and digestion in grass shrimp pre-exposed to dietary mercury.

PubMed

Seebaugh, David R; Wallace, William G; L'amoreaux, William J; Stewart, Gillian M

2012-08-01

Grass shrimp Palaemonetes pugio were fed mercury (Hg)-contaminated oligochaetes for 15 days and analyzed for Hg, cadmium (Cd), and carbon assimilation efficiencies (AE) as well as toxicological end points related to digestion. Disproportionate increases in stable Hg concentrations in shrimp did not appear to be related to partitioning to trophically available Hg in worms. Hg AE by pre-exposed shrimp reached a plateau (approximately 53 %), whereas Cd AE varied (approximately 40-60 %) in a manner that was not dose-dependent. Carbon AE did not differ among treatments (approximately 69 %). Gut residence time was not impacted significantly by Hg pre-exposure (grand median approximately 465 min), however, there was a trend between curves showing percentages of individuals with markers in feces over time versus treatment. Feces-elimination rate did not vary with dietary pre-exposure. Extracellular protease activity varied approximately 1.9-fold but did not exhibit dose-dependency. pH increased over the range of Hg pre-exposures within the anterior (pH approximately 5.33-6.51) and posterior (pH approximately 5.29-6.25) regions of the cardiac proventriculus and Hg assimilation exhibited a negative relationship to hydrogen ion concentrations. The results of this study indicate that previous Hg ingestion can elicit post-assimilatory impacts on grass shrimp digestive physiology, which may, in turn, influence Hg assimilation during subsequent digestive cycles.

New head equivalent phantom for task and image performance evaluation representative for neurovascular procedures occurring in the Circle of Willis

NASA Astrophysics Data System (ADS)

Ionita, Ciprian N.; Loughran, Brendan; Jain, Amit; Swetadri Vasan, S. N.; Bednarek, Daniel R.; Levy, Elad; Siddiqui, Adnan H.; Snyder, Kenneth V.; Hopkins, L. N.; Rudin, Stephen

2012-03-01

Phantom equivalents of different human anatomical parts are routinely used for imaging system evaluation or dose calculations. The various recommendations on the generic phantom structure given by organizations such as the AAPM, are not always accurate when evaluating a very specific task. When we compared the AAPM head phantom containing 3 mm of aluminum to actual neuro-endovascular image guided interventions (neuro-EIGI) occurring in the Circle of Willis, we found that the system automatic exposure rate control (AERC) significantly underestimated the x-ray parameter selection. To build a more accurate phantom for neuro-EIGI, we reevaluated the amount of aluminum which must be included in the phantom. Human skulls were imaged at different angles, using various angiographic exposures, at kV's relevant to neuro-angiography. An aluminum step wedge was also imaged under identical conditions, and a correlation between the gray values of the imaged skulls and those of the aluminum step thicknesses was established. The average equivalent aluminum thickness for the skull samples for frontal projections in the Circle of Willis region was found to be about 13 mm. The results showed no significant changes in the average equivalent aluminum thickness with kV or mAs variation. When a uniform phantom using 13 mm aluminum and 15 cm acrylic was compared with an anthropomorphic head phantom the x-ray parameters selected by the AERC system were practically identical. These new findings indicate that for this specific task, the amount of aluminum included in the head equivalent must be increased substantially from 3 mm to a value of 13 mm.

226-237 E. Ontario, April 2016, Lindsay Light Radiological Survey

EPA Pesticide Factsheets

Field gamma measurements did not exceed the field instrument threshold equivalent to the USEPA removal actionlevel and ranged from a minimum of 6,000 cpm to a maximum of approximately 9,000 cpm unshielded.

330-334 E. Ontario, April 2016, Lindsay Light Radiological Survey

EPA Pesticide Factsheets

Field gamma measurement did not exceed the field instrument threshold equivalent to the USEPA removal actionlevel and ranged from a minimum of 5,700 cpm to a maximum of approximately 13,100 cpm unshielded.

Photoproduction of dileptons and photons in p -p collisions at the Large Hadron Collider energies

NASA Astrophysics Data System (ADS)

Ma, Zhi-Lei; Zhu, Jia-Qing

2018-03-01

The production of large pT dileptons and photons originating from photoproduction processes in p-p collisions at Large Hadron Collider energies is calculated. The comparisons between the exact treatment results and the ones of the equivalent photon approximation approach are expressed as the Q2 (the virtuality of photon) and pT distributions. The method developed by Martin and Ryskin is used for avoiding double counting when the coherent and incoherent contributions are considered simultaneously. The numerical results indicate that the equivalent photon approximation is only effective in small Q2 region and can be used for coherent photoproduction processes with proper choice of Qmax2 (the choices Qmax2˜s ^ or ∞ will cause obvious errors), but cannot be used for incoherent photoproduction processes. The exact treatment is needed to deal accurately with the photoproduction of large pT dileptons and photons.

Household air pollution following replacement of traditional open fire with an improved rocket type cookstove.

PubMed

Ochieng, Caroline; Vardoulakis, Sotiris; Tonne, Cathryn

2017-02-15

Cooking with biomass fuel is an important source of household air pollution (HAP) in developing countries, and a leading risk factor for ill-health. Although various designs of "improved cookstoves" (ICS) have been promoted as HAP interventions in these settings, few of them have undergone in-field evaluation, partly due to the challenge of conducting field measurements in remote settings. In this study we assessed the change in carbon monoxide (CO) exposure following the replacement of the traditional three-stone stove with a popular ICS in 49 homes in Western Kenya. We also assessed the suitability of using kitchen CO as a proxy for kitchen PM 2.5 . Reduction in 48h mean kitchen CO was 3.1ppm (95% CI: -8.1, 1.8) and in personal CO was 0.9ppm (95% CI: -4.3, 2.6) following stove replacements. Overall, 48-h kitchen and personal CO exposures were lower after stove replacement (28% and 12%, respectively) but with wide confidence intervals that also suggested possible increases in exposure. There were statistically significant reductions in peak kitchen and personal CO concentrations represented by the 8-h 95th percentile: reductions of 26.1ppm (95% CI: -44.6, -7.6) and 8.0ppm (95% CI: -12.2, -3.8), respectively. This is equivalent to 53% reduction in kitchen CO and 39% reduction in personal CO. We found good correlation between kitchen CO and PM 2.5 concentrations overall (r=0.73, n=33 over averaging periods approximating 1day), which varied by time of day and exposure setting. These variations limit the applicability of CO as a proxy measure for PM 2.5 concentrations. A combination of interventions, including better designed stoves, improved ventilation and cleaner fuels, may be needed to reduce HAP to levels that are likely to improve health. Copyright © 2016. Published by Elsevier B.V.

Smaller Cerebellar Growth and Poorer Neurodevelopmental Outcomes in Very Preterm Infants Exposed to Neonatal Morphine.

PubMed

Zwicker, Jill G; Miller, Steven P; Grunau, Ruth E; Chau, Vann; Brant, Rollin; Studholme, Colin; Liu, Mengyuan; Synnes, Anne; Poskitt, Kenneth J; Stiver, Mikaela L; Tam, Emily W Y

2016-05-01

To examine the relationship between morphine exposure and growth of the cerebellum and cerebrum in very preterm neonates from early in life to term-equivalent age, as well as to examine morphine exposure and brain volumes in relation to neurodevelopmental outcomes at 18 months corrected age (CA). A prospective cohort of 136 very preterm neonates (24-32 weeks gestational age) was serially scanned with magnetic resonance imaging near birth and at term-equivalent age for volumetric measurements of the cerebellum and cerebrum. Motor outcomes were assessed with the Peabody Developmental Motor Scales, Second Edition and cognitive outcomes with the Bayley Scales of Infant and Toddler Development, Third Edition at 18 months CA. Generalized least squares models and linear regression models were used to assess relationships between morphine exposure, brain volumes, and neurodevelopmental outcomes. A 10-fold increase in morphine exposure was associated with a 5.5% decrease in cerebellar volume, after adjustment for multiple clinical confounders and total brain volume (P = .04). When infants exposed to glucocorticoids were excluded, the association of morphine was more pronounced, with an 8.1% decrease in cerebellar volume. Morphine exposure was not associated with cerebral volume (P = .30). Greater morphine exposure also predicted poorer motor (P < .001) and cognitive outcomes (P = .006) at 18 months CA, an association mediated, in part, by slower brain growth. Morphine exposure in very preterm neonates is independently associated with impaired cerebellar growth in the neonatal period and poorer neurodevelopmental outcomes in early childhood. Alternatives to better manage pain in preterm neonates that optimize brain development and functional outcomes are urgently needed. Copyright © 2016 Elsevier Inc. All rights reserved.

Late emerging effects of prenatal and early postnatal nicotine exposure on the cholinergic system and anxiety-like behavior.

PubMed

Eppolito, Amy K; Bachus, Susan E; McDonald, Craig G; Meador-Woodruff, James H; Smith, Robert F

2010-01-01

Animal models of prenatal nicotine exposure clearly indicate that nicotine is a neuroteratogen. Some of the persisting effects of prenatal nicotine exposure include low birth weight, behavioral changes and deficits in cognitive function, although few studies have looked for neurobehavioral and neurochemical effects that might persist throughout the lifespan. Pregnant rats were given continuous infusions of nicotine (0.96mg/kg/day or 2.0mg/kg/day, freebase) continuing through the third trimester equivalent, a period of rapid brain development. Because the third trimester equivalent occurs postnatally in the rat (roughly the first week of life) nicotine administration to neonate pups continued via maternal milk until postnatal day (P) 10. Exposure to nicotine during pre- and early postnatal development had an anxiogenic effect on adult rats (P75) in the elevated plus maze (EPM), and blocked extinction learning in a fear conditioning paradigm, suggesting that pre- and postnatal nicotine exposure affect anxiety-like behavior and cognitive function well into adulthood. In contrast, nicotine exposure had no effect on anxiety-like behaviors in the EPM in adolescent animals (P30). Analysis of mRNA for the alpha4, alpha7, and beta2 subunits of nicotinic acetylcholine receptors revealed lower expression of these subunits in the adult hippocampus and medial prefrontal cortex following pre- and postnatal nicotine exposure, suggesting that nicotine altered the developmental trajectory of the brain. These long-term behavioral and neurochemical changes strengthen the case for discouraging cigarette smoking during pregnancy and clearly indicate that the use of the patch as a smoking cessation aid during pregnancy is not a safe alternative.

Smaller Cerebellar Growth and Poorer Neurodevelopmental Outcomes in Very Preterm Infants exposed to morphine

PubMed Central

Zwicker, Jill G; Miller, Steven P; Grunau, Ruth E; Chau, Vann; Brant, Rollin; Studholme, Colin; Liu, Mengyuan; Synnes, Anne; Poskitt, Kenneth J; Stiver, Mikaela L; Tam, Emily WY

2017-01-01

Objective To examine the relationship between morphine exposure and growth of the cerebellum and cerebrum in very preterm neonates from early in life to term-equivalent age, as well as to examine morphine exposure and brain volumes in relation to neurodevelopmental outcomes at 18 months corrected age (CA). Study design A prospective cohort of 136 very preterm neonates (24–32 weeks gestational age) was serially scanned with MRI near birth and at term-equivalent age for volumetric measurements of the cerebellum and cerebrum. Motor outcomes were assessed with the Peabody Scales of Motor Development-2 and cognitive outcomes with the Bayley-III at 18 months CA. Generalized least squares models and linear regression models were used to assess relationships between morphine exposure, brain volumes, and neurodevelopmental outcomes. Results A 10-fold increase in morphine exposure was associated with a 5.5% decrease in cerebellar volume, after adjustment for multiple clinical confounders and total brain volume (P=0.04). When infants exposed to glucocorticoids were excluded, the association of morphine was more pronounced, with an 8.2% decrease in cerebellar volume. Morphine exposure was not associated with cerebral volume (P=0.30). Greater morphine exposure also predicted poorer motor (P<0.001) and cognitive outcomes (P=0.006) at 18 months CA, an association mediated, in part, by slower brain growth. Conclusions Morphine exposure in very preterm neonates is independently associated with impaired cerebellar growth in the neonatal period and poorer neurodevelopmental outcomes in early childhood. Alternatives to better manage pain in preterm neonates that optimize brain development and functional outcomes are urgently needed. PMID:26763312

Comparison of exact solution with Eikonal approximation for elastic heavy ion scattering

NASA Technical Reports Server (NTRS)

Dubey, Rajendra R.; Khandelwal, Govind S.; Cucinotta, Francis A.; Maung, Khin Maung

1995-01-01

A first-order optical potential is used to calculate the total and absorption cross sections for nucleus-nucleus scattering. The differential cross section is calculated by using a partial-wave expansion of the Lippmann-Schwinger equation in momentum space. The results are compared with solutions in the Eikonal approximation for the equivalent potential and with experimental data in the energy range from 25A to 1000A MeV.

Gravity, the third dimension of life support in space

NASA Technical Reports Server (NTRS)

Burton, Russell R.

1994-01-01

The ascent of the human into high altitudes required a 2-D life support system that supplied: oxygen, and heat. At lower altitudes, increased oxygen concentration in the inhaled gases was useful, but at higher altitudes for longer durations, this 'clever' life support approach was no longer adequate--physiologic requirements had to provide a natural pressure-based environment. In space, the life support system requires a third dimension, gravity. Although substituting for gravity has been successful on a limited number of physiologic functions for short-duration stays in space, long durations will require the effects of the real thing for critical physiologic functions. It has been known for over a hundred years that the forces of acceleration (G) and gravity are equivalent. Therefore, gravitational stimulation in space can be achieved with centrifugation. However, for this stimulation to be effective, the dosage of G required to maintain normal physiologic function must be determined. An approximation of this dosage of G for the human can be determined with 3-day bed-rest studies including periodic centrifuge exposure. Recent research on this topic is reviewed.

Mink liver TEQs and reproductive NOAEL resulting from dietary exposure to fish from Saginaw Bay

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

Tillitt, D.E.; Gale, R.W.; Peterman, P.H.

1994-12-31

Mink are known to be very sensitive to the toxic effects of planar halogenated hydrocarbons (PHHs). Previously the authors reported the reproductive effects in mink fed a diet containing 10, 20, or 40% fish taken from Saginaw Bay, Lake Huron. In this presentation the authors report the complete chemical analyses of the diets and the adult mink livers, along with a comparison of an additive model of toxicity with the results of the H411E bioassay on these samples. The H411E bioassay consistently estimated greater dioxin toxic-equivalents (TEQS) as compared to an additive model of toxicity and chemical analyses. TEQs derivedmore » from chemical analyses accounted for approximately 60% of the TEQs observed with the H411E bioassay. The difference is likely due to the presence of compounds which were not quantitated as opposed to synergistic interactions of the mixtures. Significant reproductive effects were observed in the lowest treatment group (10% fish, or 19.4 pg TEQs/g). The implications of these chemical and bioassay analyses on the calculation of a NOAEL will be discussed.« less

Physiological response of juvenile rainbow trout to chronic low level exposures of waterborne silver.

PubMed

Galvez, F; Hogstrand, C; Wood, C M

1998-02-01

The physiological effects of chronic exposure to AgNO3 in moderately hard freshwater were investigated in juvenile rainbow trout (Oncorhynchus mykiss Walbaum). Two separate 28-day exposures were performed at silver concentrations of 0.5 and 2.0 micrograms/L in flowing Hamilton dechlorinated tap water. Exposure to 0.5 microgram/L Ag resulted in a slight increase (approximately 14.9%) in food consumption, whereas growth rates remained unaltered. Both plasma Na+ and Cl- levels were significantly decreased by 11.8% and 9.3%, respectively at day 16 of the exposure. Hepatic Ag concentrations were elevated approximately 4-fold in 0.5 microgram/L Ag-exposed fish. However, no significant increases in liver metallothionein (MT) concentrations were noted. No mortalities were observed during this 28-day exposure. In comparison, chronic exposure to 2.0 micrograms/L Ag resulted in a 28.8% decrease in food consumption and a 43.0% reduction in growth rate. Plasma [Na+] was decreased by 18.3%, whereas plasma [Cl-] was reduced by 12.2% at day 7. At both concentrations of silver, plasma ion concentrations appeared to recover thereafter. Silver accumulated steadily in the liver up until day 15 when concentrations were 39.7 micrograms/g wet weight (285-fold increase) above control levels. In addition, MT levels were increased by 81.2% at day 7. Silver exposure at 2.0 micrograms/L resulted in approximately 15.0% mortality over the 28-day period.

Measurement of cardiopulmonary performance during acute exposure to a 2440-m equivalent atmosphere

NASA Technical Reports Server (NTRS)

Levitan, B. M.; Bungo, M. W.

1982-01-01

Each of 20 subjects (ranging in age from 18 to 38 years, 15 being male, five female) was given two Bruce Protocol symptom-limited maximum treadmill stress tests, breathing sea-level compressed air (20.9% O2) for one test and a 2440-m equivalent (15.5% O2) for the other. A significant difference was found to exist between measured VO2 max (p less than 0.0002) and exercise time (p less than 0.0004) for the two conditions. No significant differences were observed in heart rate or the recovery time to a respiratory quotient of less than 1. Hemoglobin saturation, as measured by an ear oximeter, averaged 95% for sea-level and 91% for the 2440-m equivalent gases. These results support a 2440-m equivalent contingency atmosphere in the Space Shuttle prior to donning a low-pressure suit for the purpose reducing nitrogen washout times.

Radon and leukemia in the Danish study: another source of dose.

PubMed

Harley, Naomi H; Robbins, Edith S

2009-10-01

An epidemiologic study of childhood leukemia in Denmark (2,400 cases; 6,697 controls) from 1968 to 1994 suggested a weak, but statistically significant, association of residential radon exposure and acute childhood lymphoblastic leukemia (ALL). The Danish study estimated a relative risk (RR) = 1.56 (95% CI, 1.05-2.30) for a cumulative exposure of 1,000 Bq m-3 y. For an exposure duration of 10 y their RR corresponds to a radon concentration of 100 Bq m-3. There are two dose pathways of interest where alpha particles could damage potential stem cells for ALL. One is the alpha dose to bone marrow, and two is the dose to bronchial mucosa where an abundance of circulating lymphocytes is found. Compared with an exposure of about 1 mSv y-1 from natural external background, radon and decay products contribute an additional 10 to 60% to the bone marrow equivalent dose. The other pathway for exposure of T (or B) lymphocytes is within the tracheobronchial epithelium (BE). Inhaled radon decay products deposit on the relatively small area of airway surfaces and deliver a significant dose to the nearby basal or mucous cells implicated in human lung cancer. Lymphocytes are co-located with basal cells and are half as abundant. Using a 10-y exposure to 100 Bq m-3, our dose estimates suggest that the equivalent dose to these lymphocytes could approach 1 Sv. The relatively high dose estimate to lymphocytes circulating through the BE, potential precursor cells for ALL, provides a dose pathway for an association.

Construction of vapor chambers used to expose mice to alcohol during the equivalent of all three trimesters of human development.

PubMed

Morton, Russell A; Diaz, Marvin R; Topper, Lauren A; Valenzuela, C Fernando

2014-07-13

Exposure to alcohol during development can result in a constellation of morphological and behavioral abnormalities that are collectively known as Fetal Alcohol Spectrum Disorders (FASDs). At the most severe end of the spectrum is Fetal Alcohol Syndrome (FAS), characterized by growth retardation, craniofacial dysmorphology, and neurobehavioral deficits. Studies with animal models, including rodents, have elucidated many molecular and cellular mechanisms involved in the pathophysiology of FASDs. Ethanol administration to pregnant rodents has been used to model human exposure during the first and second trimesters of pregnancy. Third trimester ethanol consumption in humans has been modeled using neonatal rodents. However, few rodent studies have characterized the effect of ethanol exposure during the equivalent to all three trimesters of human pregnancy, a pattern of exposure that is common in pregnant women. Here, we show how to build vapor chambers from readily obtainable materials that can each accommodate up to six standard mouse cages. We describe a vapor chamber paradigm that can be used to model exposure to ethanol, with minimal handling, during all three trimesters. Our studies demonstrate that pregnant dams developed significant metabolic tolerance to ethanol. However, neonatal mice did not develop metabolic tolerance and the number of fetuses, fetus weight, placenta weight, number of pups/litter, number of dead pups/litter, and pup weight were not significantly affected by ethanol exposure. An important advantage of this paradigm is its applicability to studies with genetically-modified mice. Additionally, this paradigm minimizes handling of animals, a major confound in fetal alcohol research.

Screening of hormone-like activities in bottled waters available in Southern Spain using receptor-specific bioassays.

PubMed

Real, Macarena; Molina-Molina, José-Manuel; Jiménez-Díaz, Inmaculada; Arrebola, Juan Pedro; Sáenz, José-María; Fernández, Mariana F; Olea, Nicolás

2015-01-01

Bottled water consumption is a putative source of human exposure to endocrine-disrupting chemicals (EDCs). Research has been conducted on the presence of chemicals with estrogen-like activity in bottled waters and on their estrogenicity, but few data are available on the presence of hormonal activities associated with other nuclear receptors (NRs). The aim of this study was to determine the presence of endocrine activities dependent on the activation of human estrogen receptor alpha (hERa) and/or androgen receptor (hAR) in water in glass or plastic bottles sold to consumers in Southern Spain. Hormone-like activities were evaluated in 29 bottled waters using receptor-specific bioassays based on reporter gene expression in PALM cells [(anti-)androgenicity] and cell proliferation assessment in MCF-7 cells [(anti-)estrogenicity] after optimized solid phase extraction (SPE). All of the water samples analyzed showed hormonal activity. This was estrogenic in 79.3% and anti-estrogenic in 37.9% of samples and was androgenic in 27.5% and anti-androgenic in 41.3%, with mean concentrations per liter of 0.113pM 17β-estradiol (E2) equivalent units (E2Eq), 11.01pM anti-estrogen (ICI 182780) equivalent units (ICI 182780Eq), 0.33pM methyltrienolone (R1881) equivalent units (R1881Eq), and 0.18nM procymidone equivalent units (ProcEq). Bottled water consumption contributes to EDC exposure. Hormone-like activities observed in waters from both plastic and glass bottles suggest that plastic packaging is not the sole source of contamination and that the source of the water and bottling process may play a role, among other factors. Further research is warranted on the cumulative effects of long-term exposure to low doses of EDCs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparative chronic toxicity of imidacloprid, clothianidin, and thiamethoxam to Chironomus dilutus and estimation of toxic equivalency factors.

PubMed

Cavallaro, Michael C; Morrissey, Christy A; Headley, John V; Peru, Kerry M; Liber, Karsten

2017-02-01

Nontarget aquatic insects are susceptible to chronic neonicotinoid insecticide exposure during the early stages of development from repeated runoff events and prolonged persistence of these chemicals. Investigations on the chronic toxicity of neonicotinoids to aquatic invertebrates have been limited to a few species and under different laboratory conditions that often preclude direct comparisons of the relative toxicity of different compounds. In the present study, full life-cycle toxicity tests using Chironomus dilutus were performed to compare the toxicity of 3 commonly used neonicotinoids: imidacloprid, clothianidin, and thiamethoxam. Test conditions followed a static-renewal exposure protocol in which lethal and sublethal endpoints were assessed on days 14 and 40. Reduced emergence success, advanced emergence timing, and male-biased sex ratios were sensitive responses to low-level neonicotinoid exposure. The 14-d median lethal concentrations for imidacloprid, clothianidin, and thiamethoxam were 1.52 μg/L, 2.41 μg/L, and 23.60 μg/L, respectively. The 40-d median effect concentrations (emergence) for imidacloprid, clothianidin, and thiamethoxam were 0.39 μg/L, 0.28 μg/L, and 4.13 μg/L, respectively. Toxic equivalence relative to imidacloprid was estimated through a 3-point response average of equivalencies calculated at 20%, 50%, and 90% lethal and effect concentrations. Relative to imidacloprid (toxic equivalency factor [TEF] = 1.0), chronic (lethality) 14-d TEFs for clothianidin and thiamethoxam were 1.05 and 0.14, respectively, and chronic (emergence inhibition) 40-d TEFs were 1.62 and 0.11, respectively. These population-relevant endpoints and TEFs suggest that imidacloprid and clothianidin exert comparable chronic toxicity to C. dilutus, whereas thiamethoxam induced comparable effects only at concentrations an order of magnitude higher. However, the authors caution that under field conditions, thiamethoxam readily degrades to clothianidin, thereby likely enhancing toxicity. Environ Toxicol Chem 2017;36:372-382. © 2016 SETAC. © 2016 SETAC.

Protracted exposure to fallout: the Rongelap and Utirik experience.

PubMed

Lessard, E T; Miltenberger, R P; Cohn, S H; Musolino, S V; Conard, R A

1984-03-01

From June 1946 to August 1958, the U.S. Department of Defense and the U.S. Atomic Energy Commission (AEC) conducted nuclear weapons tests in the Northern Marshall Islands. On 1 March 1954, BRAVO, an above-ground test in the Castle series, produced high levels of radioactive material, some of which subsequently fell on Rongelap and Utirik Atolls due to an unexpected wind shift. On 3 March 1954, the inhabitants of these atolls were moved out of the affected area. They later returned to Utirik in June 1954 and to Rongelap in June 1957. Comprehensive environmental and personnel radiological monitoring programs were initiated in the mid 1950s by Brookhaven National Laboratory to ensure that body burdens of the exposed Marshallese subjects remained within AEC guidelines. Their body-burden histories and calculated activity ingestion rate patterns post-return are presented along with estimates of internal committed effective dose equivalents. External exposure data are also included. In addition, relationships between body burden or urine-activity concentration and declining continuous intake were developed. The implications of these studies are: (1) the dietary intake of 137Cs was a major component contributing to the committed effective dose equivalent for the years after the initial contamination of the atolls; (2) for persons whose diet included fish, 65Zn was a major component of committed effective dose equivalent during the first years post-return; (3) a decline in the daily activity ingestion rate greater than that resulting from radioactive decay of the source was estimated for 137Cs, 65Zn, 90Sr and 60Co; (4) the relative impact of each nuclide on the estimate of committed effective dose equivalent was dependent upon the time interval between initial contamination and rehabilitation; and (5) the internal committed effective dose equivalent exceeded the external dose equivalent by a factor of 1.1 at Utirik and 1.5 at Rongelap during the rehabitation period. Few reliable 239Pu measurements on human excreta were made. An analysis of the tentative data leads to the conclusion that a reliable estimate of committed effective dose equivalent requires further research.

Reproduction of exact solutions of Lipkin model by nonlinear higher random-phase approximation

NASA Astrophysics Data System (ADS)

Terasaki, J.; Smetana, A.; Šimkovic, F.; Krivoruchenko, M. I.

2017-10-01

It is shown that the random-phase approximation (RPA) method with its nonlinear higher generalization, which was previously considered as approximation except for a very limited case, reproduces the exact solutions of the Lipkin model. The nonlinear higher RPA is based on an equation nonlinear on eigenvectors and includes many-particle-many-hole components in the creation operator of the excited states. We demonstrate the exact character of solutions analytically for the particle number N = 2 and numerically for N = 8. This finding indicates that the nonlinear higher RPA is equivalent to the exact Schrödinger equation.

Vitamin D intake needed to maintain target serum 25-hydroxyvitamin D concentrations in participants with low sun exposure and dark skin pigmentation is substantially higher than current recommendations.

PubMed

Hall, Laura M; Kimlin, Michael G; Aronov, Pavel A; Hammock, Bruce D; Slusser, James R; Woodhouse, Leslie R; Stephensen, Charles B

2010-03-01

Cutaneous cholecalciferol synthesis has not been considered in making recommendations for vitamin D intake. Our objective was to model the effects of sun exposure, vitamin D intake, and skin reflectance (pigmentation) on serum 25-hydroxyvitamin D (25[OH]D) in young adults with a wide range of skin reflectance and sun exposure. Four cohorts of participants (n = 72 total) were studied for 7-8 wk in the fall, winter, spring, and summer in Davis, CA [38.5 degrees N, 121.7 degrees W, Elev. 49 ft (15 m)]. Skin reflectance was measured using a spectrophotometer, vitamin D intake using food records, and sun exposure using polysulfone dosimeter badges. A multiple regression model (R(2) = 0.55; P < 0.0001) was developed and used to predict the serum 25(OH)D concentration for participants with low [median for African ancestry (AA)] and high [median for European ancestry (EA)] skin reflectance and with low [20th percentile, approximately 20 min/d, approximately 18% body surface area (BSA) exposed] and high (80th percentile, approximately 90 min/d, approximately 35% BSA exposed) sun exposure, assuming an intake of 200 iu/d (5 ug/d). Predicted serum 25(OH)D concentrations for AA individuals with low and high sun exposure in the winter were 24 and 42 nmol/L and in the summer were 40 and 60 nmol/L. Corresponding values for EA individuals were 35 and 60 nmol/L in the winter and in the summer were 58 and 85 nmol/L. To achieve 25(OH)D > or =75 nmol/L, we estimate that EA individuals with high sun exposure need 1300 iu/d vitamin D intake in the winter and AA individuals with low sun exposure need 2100-3100 iu/d year-round.

A study on quantitative analysis of exposure dose caused by patient depending on time and distance in nuclear medicine examination

NASA Astrophysics Data System (ADS)

Kim, H. S.; Cho, J. H.; Shin, S. G.; Dong, K. R.; Chung, W. K.; Chung, J. E.

2013-01-01

This study evaluated possible actions that can help protect against and reduce radiation exposure by measuring the exposure dose for each type of isotope that is used frequently in nuclear medicine before performing numerical analysis of the effective half-life based on the measurement results. From July to August in 2010, the study targeted 10, 6 and 5 people who underwent an 18F-FDG (fludeoxyglucose) positron emission tomography (PET) scan, 99mTc-HDP bone scan, and 201Tl myocardial single-photon emission computed tomography (SPECT) scan, respectively, in the nuclear medicine department. After injecting the required medicine into the subjects, a survey meter was used to measure the dose depending on the distance from the heart and time elapsed. For the 18F-FDG PET scan, the dose decreased by approximately 66% at 90 min compared to that immediately after the injection and by 78% at a distance of 1 m compared to that at 0.3 m. In the 99mTc-HDP bone scan, the dose decreased by approximately 71% in 200 min compared to that immediately after the injection and by approximately 78% at a distance of 1 m compared to that at 0.3 m. In the 201Tl myocardial SPECT scan, the dose decreased by approximately 30% in 250 min compared to that immediately after the injection and by approximately 55% at a distance of 1 m compared to that at 0.3 m. In conclusion, the dose decreases by a large margin depending on the distance and time. In conclusion, this study measured the exposure doses by isotopes, distance from the heart and exposure time, and found that the doses were reduced significantly according the distance and the time.

Photoprotection by pistachio bioactives in a 3-dimensional human skin equivalent tissue model.

PubMed

Chen, C-Y Oliver; Smith, Avi; Liu, Yuntao; Du, Peng; Blumberg, Jeffrey B; Garlick, Jonathan

2017-09-01

Reactive oxygen species (ROS) generated during ultraviolet (UV) light exposure can induce skin damage and aging. Antioxidants can provide protection against oxidative injury to skin via "quenching" ROS. Using a validated 3-dimensional (3D) human skin equivalent (HSE) tissue model that closely mimics human skin, we examined whether pistachio antioxidants could protect HSE against UVA-induced damage. Lutein and γ-tocopherol are the predominant lipophilic antioxidants in pistachios; treatment with these compounds prior to UVA exposure protected against morphological changes to the epithelial and connective tissue compartments of HSE. Pistachio antioxidants preserved overall skin thickness and organization, as well as fibroblast morphology, in HSE exposed to UVA irradiation. However, this protection was not substantiated by the analysis of the proliferation of keratinocytes and apoptosis of fibroblasts. Additional studies are warranted to elucidate the basis of these discordant results and extend research into the potential role of pistachio bioactives promoting skin health.

Constraining controls on carbonate sequences with high-resolution chronostratigraphy: Upper Miocene, Cabo de Gata region, SE Spain

USGS Publications Warehouse

Montgomery, P.; Farr, M.R.; Franseen, E.K.; Goldstein, R.H.

2001-01-01

A high-resolution chronostratigraphy has been developed for Miocene shallow-water carbonate strata in the Cabo de Gata region of SE Spain for evaluation of local, regional and global factors that controlled platform architecture prior to and during the Messinian salinity crisis. Paleomagnetic data were collected from strata at three localities. Mean natural remanent magnetization (NRM) ranges between 1.53 ?? 10-8 and 5.2 ?? 10-3 Am2/kg. Incremental thermal and alternating field demagnetization isolated the characteristic remanent magnetization (ChRM). Rock magnetic studies show that the dominant magnetic mineral is magnetite, but mixtures of magnetite and hematite occur. A composite chronostratigraphy was derived from five stratigraphic sections. Regional stratigraphic data, biostratigraphic data, and an 40Ar/39Ar date of 8.5 ?? 0.1 Ma, for an interbedded volcanic flow, place the strata in geomagnetic polarity Chrons C4r to C3r. Sequence-stratigraphic and diagenetic evidence indicate a major unconformity at the base of depositional sequence (DS)3 that contains a prograding reef complex, suggesting that approximately 250 000 yr of record (Subchrons C3Br.2r to 3Br.1r) are missing near the Messinian-Tortonian boundary. Correlation to the GPTS shows that the studied strata represent five third- to fourth-order DSs. Basal units are temperate to subtropical ramps (DS1A, DS1B, DS2); these are overlain by subtropical to tropical reefal platforms (DS3), which are capped by subtropical to tropical cyclic carbonates (Terminal Carbonate Complex, TCC). Correlation of the Cabo de Gata record to the Melilla area of Morocco, and the Sorbas basin of Spain indicate that early - Late Tortonian ramp strata from these areas are partially time-equivalent. Similar strata are extensively developed in the Western Mediterranean and likely were influenced by a cool climate or influx of nutrients during an overall rise in global sea-level. After ramp deposition, a sequence boundary (SB3) in Cabo de Gata correlates with a sequence boundary in Morocco and a published third-order eustatic fall suggesting at least a partial eustatic control for the sequence boundary. Coral reefs began to develop earlier in Cabo de Gata than at Melilla or Sorbas, arguing for local factors affecting this major environmental transition. Later Messinian reefs (DS3) from all areas are time-equivalent, suggesting a regional or global control on their formation. Some Halimeda-rich horizons in the Western Mediterranean are not time-equivalent event strata as hypothesized by others. Correlation of the relative sea-level curve for the fringing reef complex (DS3) with a published eustatic curve suggests at least a partial third-order global eustatic control for the highstand part of the sequence. Downstepping DS3 reefs and initial subaerial exposure of earlier DS3 reef strata approximately correlate with initiation of a series of subaerial unconformities in the South Pacific. The longer-term relative fall in sea-level during DS3 downstepping reef progradation does not correlate with a published third-order eustatic fall. Eustatic sea-level fluctuations may have been associated with initiation of the Mediterranean Messinian salinity crisis, but the longer-term fall may have been linked to tectonic uplift in the Mediterranean region. Widespread distribution of 'TCC-style' cycles of approximately the same age suggests a regional (Western Mediterranean) or global control on sea-level change responsible for TCC cycles. In addition, four subaerial exposure-capped TCC cycles may correlate with similar subaerial unconformities in the South Pacific, suggesting at least a partial eustatic control on TCC cyclicity. The high rates of relative sea-level change needed to generate a minimum of 25-30 m sea-level changes associated with each cycle are consistent with glacio-eustacy along with rapid evaporitic drawdown in the Mediterranean. ?? 2001 Elsevier Science B.V. All rights reserved.

Self-reported sleep disturbances due to railway noise: exposure-response relationships for nighttime equivalent and maximum noise levels.

PubMed

Aasvang, Gunn Marit; Moum, Torbjorn; Engdahl, Bo

2008-07-01

The objective of the present survey was to study self-reported sleep disturbances due to railway noise with respect to nighttime equivalent noise level (L(p,A,eq,night)) and maximum noise level (L(p,A,max)). A sample of 1349 people in and around Oslo in Norway exposed to railway noise was studied in a cross-sectional survey to obtain data on sleep disturbances, sleep problems due to noise, and personal characteristics including noise sensitivity. Individual noise exposure levels were determined outside of the bedroom facade, the most-exposed facade, and inside the respondents' bedrooms. The exposure-response relationships were analyzed by using logistic regression models, controlling for possible modifying factors including the number of noise events (train pass-by frequency). L(p,A,eq,night) and L(p,A,max) were significantly correlated, and the proportion of reported noise-induced sleep problems increased as both L(p,A,eq,night) and L(p,A,max) increased. Noise sensitivity, type of bedroom window, and pass-by frequency were significant factors affecting noise-induced sleep disturbances, in addition to the noise exposure level. Because about half of the study population did not use a bedroom at the most-exposed side of the house, the exposure-response curve obtained by using noise levels for the most-exposed facade underestimated noise-induced sleep disturbance for those who actually have their bedroom at the most-exposed facade.

Modeling Thermal Effects for Simulation of Post Exposure Baking (PEB) Process in Positive Photoresist

NASA Astrophysics Data System (ADS)

Asai, Satoru; Hanyu, Isamu; Nunokawa, Mitsuji; Abe, Masayuki

1991-03-01

We studied the thermal effects in a positive photoresist during post exposure baking (PEB). Infrared analysis and the reduced dissolution rate in the exposed resist suggest that the carboxylic acid is decreased and/or that ECA solvent evaporates. In order to simulate the effects, we assume that the concentration of the alkali-soluble material (carboxylic acid) decreases equivalently. Our model explains PEB and enables its effects to be simulated.

Current Research and Opportunities to Address Environmental Asbestos Exposures

EPA Science Inventory

Asbestos-related diseases continue to result in approximately 120,000 deaths every year in the United States and worldwide.Although extensive research has been conducted on health effects of occupational exposures to asbestos, many issues related to environmental asbestos exposur...

Preliminary results of accelerated exposure testing of solar cell system components

NASA Technical Reports Server (NTRS)

Anagnostou, E.; Forestieri, A. F.

1977-01-01

Plastic samples and solar cell sub modules were exposed to an accelerated outdoor environment in Arizona and an accelerated simulated environment in a cyclic ultraviolet exposure tester which included humidity exposure. These tests were for preliminary screening of materials suitable for use in the manufacture of solar cell modules which are to have a 20-year lifetime. The samples were exposed for various times up to six months, equivalent to a real time exposure of four years. Suitable materials were found to be FEP-A, FEP-C, PFA, acrylic, silicone compounds and adhesives and possibly parylene. The method of packaging the sub modules was also found to be important to their performance.

Equivalent Quantum Equations in a System Inspired by Bouncing Droplets Experiments

NASA Astrophysics Data System (ADS)

Borghesi, Christian

2017-07-01

In this paper we study a classical and theoretical system which consists of an elastic medium carrying transverse waves and one point-like high elastic medium density, called concretion. We compute the equation of motion for the concretion as well as the wave equation of this system. Afterwards we always consider the case where the concretion is not the wave source any longer. Then the concretion obeys a general and covariant guidance formula, which leads in low-velocity approximation to an equivalent de Broglie-Bohm guidance formula. The concretion moves then as if exists an equivalent quantum potential. A strictly equivalent free Schrödinger equation is retrieved, as well as the quantum stationary states in a linear or spherical cavity. We compute the energy (and momentum) of the concretion, naturally defined from the energy (and momentum) density of the vibrating elastic medium. Provided one condition about the amplitude of oscillation is fulfilled, it strikingly appears that the energy and momentum of the concretion not only are written in the same form as in quantum mechanics, but also encapsulate equivalent relativistic formulas.

Physical Simulation of a Prolonged Plasma-Plume Exposure of a Space Debris Object

NASA Astrophysics Data System (ADS)

Shuvalov, V. A.; Gorev, N. B.; Tokmak, N. A.; Kochubei, G. S.

2018-05-01

A methodology has been developed for the physical (laboratory) simulation of the prolonged exposure of a space debris object to high-energy ions of a plasma plume for removing the object into low-Earth orbit with its subsequent burning in the Earth's atmosphere. The methodology is based on the equivalence criteria of two modes of exposure (in the Earth's ionosphere and in the setup) and the procedure for accelerated resource tests in terms of the sputtering of the space debris material and its deceleration by a plasma jet in the Earth's ionosphere.

NATIONAL HUMAN EXPOSURE ASSESSMENT SURVEY (NHEXAS): ANALYSIS OF EXPOSURE PATHWAYS AND ROUTES FOR ARSENIC AND LEAD IN EPA REGION 5

EPA Science Inventory

The National Human Exposure Assessment Survey (NHEXAS) Phase I field study conducted in EPA Region 5 (Great Lakes Area) provides extensive exposure data on a representative sample of approximately 250 residents of the region. Associated environmental media and biomarker (blood...

Reduction of Radiation Exposure Using Dynamic Trace Digital Angiography and Spot Fluoroscopy During Adrenal Venous Sampling

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

Morita, Satoru, E-mail: i@imodey.com; Endo, Kenji; Suzaki, Shingo

PurposeTo compare radiation exposure of adrenal venous sampling (AVS) using dynamic trace digital angiography (DTDA) and spot fluoroscopy with that using conventional methods.Materials and MethodsAVS was performed in 11 patients using DTDA and spot fluoroscopy (Group A) and 11 patients using conventional digital subtraction angiography (DSA) with collimation (Group B). Radiation exposure and image quality of adrenal venography using a five-point scale were compared between the groups.ResultsThe acquisition dose–area product (DAP) using DTDA and fluoro-DAP using spot fluoroscopy in Group A were lower than those using conventional DSA (5.3 ± 3.7 vs. 29.1 ± 20.1 Gy cm{sup 2}, p < 0.001) and collimation (33.3 ± 22.9 vs. 59.1 ± 35.7 Gy cm{sup 2}, p = 0.088)more » in Group B. The total DAP in Group A was significantly lower than that in Group B (38.6 ± 25.9 vs. 88.2 ± 53.6 Gy cm{sup 2}, p = 0.006). The peak skin dose for patients and operator radiation exposure in Group A were significantly lower than those in Group B (403 ± 340 vs. 771 ± 416 mGy, p = 0.030, and 17.1 ± 14.8 vs. 36.6 ± 21.7 μSv, p = 0.013). The image quality of DTDA (4.4 ± 0.6) was significantly higher than that of digital angiography (3.8 ± 0.9, p = 0.011) and equivalent to that of DSA (4.3 ± 0.8, p = 0.651).ConclusionsRadiation exposure during AVS can be reduced by approximately half for both patients and operators by using DTDA and spot fluoroscopy without sacrificing image quality.« less

Organochlorine and metal contaminant exposure and effects in hatching Black-Crowned Night Herons (Nycticorax nycticorax) in Delaware Bay

USGS Publications Warehouse

Rattner, B.A.; Hoffman, D.J.; Melancon, M.J.; Olsen, Glenn H.; Schmidt, S.R.; Parsons, K.C.

2000-01-01

Pea Patch Island in Delaware Bay is the site of the largest heronry north of Florida. From 1989-93, the population of nine species of wading birds numbered approximately 12,000 pairs, but has recently declined to about 7,000 pairs. Because Delaware Bay is a major shipping channel and receives anthropogenic releases of toxic substances from agricultural, industrial, and municipal point and non-point sources, contaminant exposure and effects to the heronry have been an ongoing concern. In 1997, pipping (early hatching stage) black-crowned night herons (Nycticorax nycticorax) were collected from separate nests at Pea Patch Island and from a coastal reference site, Middle Island in Rehoboth Bay, Delaware. There was no evidence of malformations or hepatic histopathological lesions in embryos, and their body and liver weights did not differ between sites. Biomarkers of petroleum hydrocarbons, polyhalogenated contaminant, and metal exposure (cytochrome P450 induction and oxidative stress responses) did not differ (p > 0.05) between sites, although activities of benzyloxy-O-dealkylase and ethoxyresorufin-O-dealkylase were somewhat elevated in 3 of the 15 embryos collected from Pea Patch Island. Concentrations of 21 organochlorine pesticides and metabolites were relatively low at both sites, with p,p'-DDE values well below the threshold associated with eggshell thinning. Although total PCB concentration was modestly elevated (p < 0.05) in Pea Patch Island heron embryos, levels of arylhydrocarbon receptor-active PCB congeners, polychlorinated dibenzodioxins and dibenzofurans, and toxic equivalents were low and did not differ between sites. Concentrations of Cd and Mn in pipping embryos from Pea Patch Island were slightly greater (p < 0.05) than values observed in Middle Island embryos, but levels of these and the other metals and metalloids (e.g., Hg and Se) were below values associated with toxicity. In conclusion, it seems unlikely that chlorinated hydrocarbon and metal contaminant exposure constitutes a direct threat to the reproductive success of black-crowned night herons at Pea Patch Island. However, low-level exposure to these contaminants may constitute one of many stressors that in combination could adversely affect the stability of the wading bird population at this large heronry.

The Solar Flare 4: 10 keV X-ray Spectrum

NASA Technical Reports Server (NTRS)

Phillips, K. J. H.

2004-01-01

The 4-10 keV solar flare spectrum includes highly excited lines of stripped Ca, Fe, and Ni ions as well as a continuum steeply falling with energy. Groups of lines at approximately 7 keV and approximately 8 keV, observed during flares by the broad-band RHESSI spectrometer and called here the Fe-line and Fe/Ni-line features, are formed mostly of Fe lines but with Ni lines contributing to the approximately 8 keV feature. Possible temperature indicators of these line features are discussed - the peak or centroid energies of the Fe-line feature, the line ratio of the Fe-line to the Fe/Ni-line features, and the equivalent width of the Fe-line feature. The equivalent width is by far the most sensitive to temperature. However, results will be confused if, as is commonly believed, the abundance of Fe varies from flare to flare, even during the course of a single flare. With temperature determined from the thermal continuum, the Fe-line feature becomes a diagnostic of the Fe abundance in flare plasmas. These results are of interest for other hot plasmas in coronal ionization equilibrium such as stellar flare plasmas, hot gas in galaxies, and older supernova remnants.

Energy expenditure, heart rate response, and metabolic equivalents (METs) of adults taking part in children's games.

PubMed

Fischer, S L; Watts, P B; Jensen, R L; Nelson, J

2004-12-01

The needs of physical activity can be seen through the lack of numbers participating in regular physical activity as well as the increase in prevalence of certain diseases such as Type II diabetes (especially in children), cardiovascular diseases, and some cancers. With the increase in preventable diseases that are caused in part by a sedentary lifestyle, a closer look needs to be taken into the role of family interaction as a means of increasing physical activity for both adults and children. Because of the many benefits of physical activity in relation to health, a family approach to achieving recommended levels of physical activity may be quite applicable. Forty volunteers were recruited from the community (20 subjects and 20 children). The volunteers played 2 games: soccer and nerfball. Data was collected over 10 minutes (5 min per game). Expired air analysis was used to calculate energy expenditure and metabolic equivalents (METs). Descriptive statistics were calculated along with a regression analysis to determine differences between the 2 games, and an ACOVA to determine any significant effects of age, child age, gender, and physical activity level on the results. For both games, average heart rate measured approximately 88%max; average METs measured approximately 6, average energy expenditure measured approximately 40 kcal. S: This study showed that adults can achieve recommended physical activity levels through these specific activities if sustained for approximately 20 min.

Derivation of the RPA (Random Phase Approximation) Equation of ATDDFT (Adiabatic Time Dependent Density Functional Ground State Response Theory) from an Excited State Variational Approach Based on the Ground State Functional.

PubMed

Ziegler, Tom; Krykunov, Mykhaylo; Autschbach, Jochen

2014-09-09

The random phase approximation (RPA) equation of adiabatic time dependent density functional ground state response theory (ATDDFT) has been used extensively in studies of excited states. It extracts information about excited states from frequency dependent ground state response properties and avoids, thus, in an elegant way, direct Kohn-Sham calculations on excited states in accordance with the status of DFT as a ground state theory. Thus, excitation energies can be found as resonance poles of frequency dependent ground state polarizability from the eigenvalues of the RPA equation. ATDDFT is approximate in that it makes use of a frequency independent energy kernel derived from the ground state functional. It is shown in this study that one can derive the RPA equation of ATDDFT from a purely variational approach in which stationary states above the ground state are located using our constricted variational DFT (CV-DFT) method and the ground state functional. Thus, locating stationary states above the ground state due to one-electron excitations with a ground state functional is completely equivalent to solving the RPA equation of TDDFT employing the same functional. The present study is an extension of a previous work in which we demonstrated the equivalence between ATDDFT and CV-DFT within the Tamm-Dancoff approximation.

Proposed phase 2/ step 2 in-vitro test on basis of EN 14561 for standardised testing of the wound antiseptics PVP-iodine, chlorhexidine digluconate, polihexanide and octenidine dihydrochloride.

PubMed

Schedler, Kathrin; Assadian, Ojan; Brautferger, Uta; Müller, Gerald; Koburger, Torsten; Classen, Simon; Kramer, Axel

2017-02-13

Currently, there is no agreed standard for exploring the antimicrobial activity of wound antiseptics in a phase 2/ step 2 test protocol. In the present study, a standardised in-vitro test is proposed, which allows to test potential antiseptics in a more realistically simulation of conditions found in wounds as in a suspension test. Furthermore, factors potentially influencing test results such as type of materials used as test carrier or various compositions of organic soil challenge were investigated in detail. This proposed phase 2/ step 2 test method was modified on basis of the EN 14561 by drying the microbial test suspension on a metal carrier for 1 h, overlaying the test wound antiseptic, washing-off, neutralization, and dispersion at serial dilutions at the end of the required exposure time yielded reproducible, consistent test results. The difference between the rapid onset of the antiseptic effect of PVP-I and the delayed onset especially of polihexanide was apparent. Among surface-active antimicrobial compounds, octenidine was more effective than chlorhexidine digluconate and polihexanide, with some differences depending on the test organisms. However, octenidine and PVP-I were approximately equivalent in efficiency and microbial spectrum, while polihexanide required longer exposure times or higher concentrations for a comparable antimicrobial efficacy. Overall, this method allowed testing and comparing differ liquid and gel based antimicrobial compounds in a standardised setting.

Space Flight-Induced Intracranial Hypertension: An Ophthalmic Review

NASA Technical Reports Server (NTRS)

Gibson, Charles Robert; Mader, Thomas H.

2010-01-01

Background: Although physiologic and pathologic changes associated with microgravity exposure have been studied extensively, the effect of this environment on the eye is largely unknown. Over the last several years, NASA s Space Medicine Division has documented astronauts presenting with varying degrees of disc edema, globe flattening, choroidal folds, cotton wool spots, and hyperopic shifts after long-duration space flight. Methods: Before and after long-duration space flight, six astronauts underwent complete eye examinations to include cycloplegic and/or manifest refraction and fundus photography. Five of these astronauts had Optical Coherence Tomography (OCT) and Magnetic Resonance Imaging (MRI) performed following their missions. Results: Following exposure to space flight of approximately 6-months duration, six astronauts had neuro-ophthalmic findings. These consisted of disc edema in four astronauts, globe flattening in four astronauts, choroidal folds in four astronauts, cotton wool spots in three astronauts, nerve fiber layer thickening by OCT in five astronauts, and decreased near vision in five astronauts. Four of the astronauts with near vision complaints had a hyperopic shift equal to or greater than + 0.50D between pre- and post-mission spherical equivalent refraction in one or both eyes (range +0.50D to +1.50D). These same four had globe flattening by MRI. Conclusions: The findings we describe may have resulted from a rise in intracranial pressure caused by microgravity fluid shifts, and could represent parts of a spectrum of ocular and cerebral responses to extended microgravity.

Adverse Reproductive and Developmental Health Outcomes Following Prenatal Exposure to a Hydraulic Fracturing Chemical Mixture in Female C57Bl/6 Mice.

PubMed

Kassotis, Christopher D; Bromfield, John J; Klemp, Kara C; Meng, Chun-Xia; Wolfe, Andrew; Zoeller, R Thomas; Balise, Victoria D; Isiguzo, Chiamaka J; Tillitt, Donald E; Nagel, Susan C

2016-09-01

Unconventional oil and gas operations using hydraulic fracturing can contaminate surface and groundwater with endocrine-disrupting chemicals. We have previously shown that 23 of 24 commonly used hydraulic fracturing chemicals can activate or inhibit the estrogen, androgen, glucocorticoid, progesterone, and/or thyroid receptors in a human endometrial cancer cell reporter gene assay and that mixtures can behave synergistically, additively, or antagonistically on these receptors. In the current study, pregnant female C57Bl/6 dams were exposed to a mixture of 23 commonly used unconventional oil and gas chemicals at approximately 3, 30, 300, and 3000 μg/kg·d, flutamide at 50 mg/kg·d, or a 0.2% ethanol control vehicle via their drinking water from gestational day 11 through birth. This prenatal exposure to oil and gas operation chemicals suppressed pituitary hormone concentrations across experimental groups (prolactin, LH, FSH, and others), increased body weights, altered uterine and ovary weights, increased heart weights and collagen deposition, disrupted folliculogenesis, and other adverse health effects. This work suggests potential adverse developmental and reproductive health outcomes in humans and animals exposed to these oil and gas operation chemicals, with adverse outcomes observed even in the lowest dose group tested, equivalent to concentrations reported in drinking water sources. These endpoints suggest potential impacts on fertility, as previously observed in the male siblings, which require careful assessment in future studies.

Adverse Reproductive and Developmental Health Outcomes Following Prenatal Exposure to a Hydraulic Fracturing Chemical Mixture in Female C57Bl/6 Mice

PubMed Central

Kassotis, Christopher D.; Bromfield, John J.; Klemp, Kara C.; Meng, Chun-Xia; Wolfe, Andrew; Zoeller, R. Thomas; Balise, Victoria D.; Isiguzo, Chiamaka J.; Tillitt, Donald E.

2016-01-01

Unconventional oil and gas operations using hydraulic fracturing can contaminate surface and groundwater with endocrine-disrupting chemicals. We have previously shown that 23 of 24 commonly used hydraulic fracturing chemicals can activate or inhibit the estrogen, androgen, glucocorticoid, progesterone, and/or thyroid receptors in a human endometrial cancer cell reporter gene assay and that mixtures can behave synergistically, additively, or antagonistically on these receptors. In the current study, pregnant female C57Bl/6 dams were exposed to a mixture of 23 commonly used unconventional oil and gas chemicals at approximately 3, 30, 300, and 3000 μg/kg·d, flutamide at 50 mg/kg·d, or a 0.2% ethanol control vehicle via their drinking water from gestational day 11 through birth. This prenatal exposure to oil and gas operation chemicals suppressed pituitary hormone concentrations across experimental groups (prolactin, LH, FSH, and others), increased body weights, altered uterine and ovary weights, increased heart weights and collagen deposition, disrupted folliculogenesis, and other adverse health effects. This work suggests potential adverse developmental and reproductive health outcomes in humans and animals exposed to these oil and gas operation chemicals, with adverse outcomes observed even in the lowest dose group tested, equivalent to concentrations reported in drinking water sources. These endpoints suggest potential impacts on fertility, as previously observed in the male siblings, which require careful assessment in future studies. PMID:27560547

Low Luminosity States of the Black Hole Candidate GX 339-4. 1; ASCA and Simultaneous Radio/RXTE Observations

NASA Technical Reports Server (NTRS)

Wilms, Joern; Nowak, Michael A.; Dove, James B.; Fender, Robert P.; DiMatteo, Tiziana

1998-01-01

We discuss a series of observations of the black hole candidate GX 339-4 in low luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets and eight separate Rossi X-ray Timing Explorer (RXTE) data sets. Three of the RXTE observations were strictly simultaneous with 843 Mega Hertz and 8.3-9.1 Giga Hertz radio observations. All of these observations have (3-9 keV) flux approximately less than 10(exp-9) ergs s(exp-1) CM(exp -2). The ASCA data show evidence for an approximately 6.4 keV Fe line with equivalent width approximately 40 eV, as well as evidence for a soft excess that is well-modeled by a power law plus a multicolor blackbody spectrum with peak temperature approximately equals 150-200 eV. The RXTE data sets also show evidence of an Fe line with equivalent widths approximately equal to 20-1OO eV. Reflection models show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. 'Sphere+disk' Comptonization models and Advection Dominated Accretion Flow (ADAF) models also provide reasonable descriptions of the RXTE data. The former models yield coronal temperatures in the range 20-50 keV and optical depths of r approximately equal to 3. The model fits to the X-ray data, however, do not simultaneously explain the observed radio properties. The most likely source of the radio flux is synchrotron emission from an extended outflow of extent greater than O(10 (exp7) GM/c2).

Comparison of Some Radiation Exposures to Mars-Trip Level

NASA Image and Video Library

2013-05-30

This graphic compares the radiation dose equivalent for several types of experiences, including a calculation for a trip from Earth to Mars based on measurements made by the RAD instrument shielded inside NASA Mars Science Laboratory spacecraft.

Identifying potential exposure reduction priorities using regional rankings based on emissions of known and suspected carcinogens to outdoor air in Canada.

PubMed

Setton, Eleanor M; Veerman, Basil; Erickson, Anders; Deschenes, Steeve; Cheasley, Roz; Poplawski, Karla; Demers, Paul A; Keller, C Peter

2015-08-22

Emissions inventories aid in understanding the sources of hazardous air pollutants and how these vary regionally, supporting targeted reduction actions. Integrating information on the relative toxicity of emitted pollutants with respect to cancer in humans helps to further refine reduction actions or recommendations, but few national programs exist in North America that use emissions estimates in this way. The CAREX Canada Emissions Mapping Project provides key regional indicators of emissions (total annual and total annual toxic equivalent, circa 2011) of 21 selected known and suspected carcinogens. The indicators were calculated from industrial emissions reported to the National Pollutant Release Inventory (NPRI) and estimates of emissions from transportation (airports, trains, and car and truck traffic) and residential heating (oil, gas and wood), in conjunction with human toxicity potential factors. We also include substance-specific annual emissions in toxic equivalent kilograms and annual emissions in kilograms, to allow for ranking substances within any region. For provinces and territories in Canada, the indicators suggest the top five substances contributing to the total toxic equivalent emissions in any region could be prioritized for further investigation. Residents of Quebec and New Brunswick may be more at risk of exposure to industrial emissions than those in other regions, suggesting that a more detailed study of exposure to industrial emissions in these provinces is warranted. Residential wood smoke may be an important emission to control, particularly in the north and eastern regions of Canada. Residential oil and gas heating, along with rail emissions contribute little to regional emissions and therefore may not be an immediate regional priority. The developed indicators support the identification of pollutants and sources for additional investigation when planning exposure reduction actions among Canadian provinces and territories, but have important limitations similar to other emissions inventory-based tools. Additional research is required to evaluate how the Emissions Mapping Project is used by different groups and organizations with respect to informing actions aimed at reducing Canadians' potential exposure to harmful air pollutants.

The Impact of Massage and Reading on Children's Pain and Anxiety After Cardiovascular Surgery: A Pilot Study.

PubMed

Staveski, Sandra L; Boulanger, Karen; Erman, Lee; Lin, Li; Almgren, Christina; Journel, Chloe; Roth, Stephen J; Golianu, Brenda

2018-06-14

The purpose of this pilot study was three-fold: 1) to evaluate the safety and feasibility of instituting massage therapy in the immediate postoperative period after congenital heart surgery, 2) to examine the preliminary results on effects of massage therapy versus standard of care plus three reading visits on postoperative pain and anxiety, and 3) to evaluate preliminary effects of opioid and benzodiazepine exposure in patients receiving massage therapy compared with reading controls. Prospective, randomized controlled trial. An academic children's hospital. Sixty pediatric heart surgery patients between ages 6 and 18 years. Massage therapy and reading. There were no adverse events related to massage or reading interventions in either group. Our investigation found no statistically significant difference in Pain or State-Trait Anxiety scores in the initial 24 hours after heart surgery (T1) and within 48 hours of transfer to the acute care unit (T2) after controlling for age, gender, and Risk Adjustment for Congenital Heart Surgery 1 score. However, children receiving massage therapy had significantly lower State-Trait Anxiety scores after receiving massage therapy at time of discharge (T3; p = 0.0075) than children receiving standard of care plus three reading visits. We found no difference in total opioid exposure during the first 3 postoperative days between groups (median [interquartile range], 0.80 mg/kg morphine equivalents [0.29-10.60] vs 1.13 mg/kg morphine equivalents [0.72-6.14]). In contrast, children receiving massage therapy had significantly lower total benzodiazepine exposure in the immediate 3 days following heart surgery (median [interquartile range], 0.002 mg/kg lorazepam equivalents [0-0.03] vs 0.03 mg/kg lorazepam equivalents [0.02-0.09], p = 0.0253, Wilcoxon rank-sum) and number of benzodiazepine PRN doses (0.5 [0-2.5] PRN vs 2 PRNs (1-4); p = 0.00346, Wilcoxon rank-sum). Our pilot study demonstrated the safety and feasibility of implementing massage therapy in the immediate postoperative period in pediatric heart surgery patients. We found decreased State-Trait Anxiety scores at discharge and lower total exposure to benzodiazepines. Preventing postoperative complications such as delirium through nonpharmacologic interventions warrants further evaluation.

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.

A preliminary evaluation of immune stimulation following exposure to metal particles and ions using the mouse popliteal lymph node assay

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

Tvermoes, Brooke E., E-mail: brooke.tvermoes@cardn

The objective of this preliminary study was to evaluate the threshold for immune stimulation in mice following local exposure to metal particles and ions representative of normal-functioning cobalt-chromium (CoCr) metal-on-metal (MoM) hip implants. The popliteal lymph node assay (PLNA) was used in this study to assess immune responses in BALB/c mice following treatment with chromium-oxide (Cr{sub 2}O{sub 3}) particles, metal salts (CoCl{sub 2}, CrCl{sub 3} and NiCl{sub 2}), or Cr{sub 2}O{sub 3} particles together with metal salts using single-dose exposures representing approximately 10 days (0.000114 mg), 19 years (0.0800 mg), and 40 years (0.171 mg) of normal implant wear. Themore » immune response elicited following treatment with Cr{sub 2}O{sub 3} particles together with metal salts was also assessed at four additional doses equivalent to approximately 1.5 months (0.0005 mg), 0.6 years (0.0025 mg), 2.3 years (0.01 mg), and 9.3 years (0.04 mg) of normal implant wear. Mice were injected subcutaneously (50 μL) into the right hind foot with the test article, or with the relevant vehicle control. The proliferative response of the draining lymph node cells (LNC) was measured four days after treatment, and stimulation indices (SI) were derived relative to vehicle controls. The PLNA was negative (SI < 3) for all Cr{sub 2}O{sub 3} particle doses, and was also negative at the lowest dose of the metal salt mixture, and the lowest four doses of the Cr{sub 2}O{sub 3} particles with metal salt mixture. The PLNA was positive (SI > 3) at the highest two doses of the metal salt mixture and the highest three doses of the Cr{sub 2}O{sub 3} particles with the metal salt mixture. The provisional NOAEL and LOAEL values identified in this study for immune activation corresponds to Co and Cr concentrations in the synovial fluid approximately 500 and 2000 times higher than that reported for normal-functioning MoM hip implants, respectively. Overall, these results indicate that normal wear conditions are unlikely to result in immune stimulation in individuals not previously sensitized to metals. - Highlights: • Immune responses in mice were assessed following treatment with Cr2O3 particles with metal salts. • The PLNA was negative (SI < 3) for all Cr2O3 particle doses. • A LOAEL for immune activation was identified at 0.04 mg of metal particles with metal salts. • A NOAEL for immune activation was identified at 0.01 mg of metal particles with metal salts.« less

Antioxidant activity of Rafflesia kerrii flower extract.

PubMed

Puttipan, Rinrampai; Okonogi, Siriporn

2014-02-01

Rafflesia kerrii has been used in Thai traditional remedies for treatment of several diseases. However, scientific data particularly on biological activities of this plant is very rare. The present study explores an antioxidant activity of R. kerrii flower (RKF). Extracting solvent and extraction procedure were found to play an important role on the activity of RKF extract. The extract obtained from water-ethanol system showed higher antioxidant activity than that from water-propylene glycol system. Fractionated extraction using different solvents revealed that methanol fractionated extract (RM) possessed the highest antioxidant activity with Trolox equivalent antioxidant capacity (TEAC) and inhibitory concentration of 50% inhibition (IC50) values of approximately 39 mM/mg and 3 μg/mL, respectively. Phytochemical assays demonstrated that RM contained extremely high quantity of phenolic content with gallic antioxidant equivalent (GAE) and quercetin equivalent (QE) values of approximately 312 mg/g and 16 mg/g, respectively. Ultraviolet-visible spectroscopy (UV- VIS) and high-pressure liquid chromatography (HPLC) indicated that gallic acid was a major component. RM which was stored at 40°C, 75% RH for 4 months showed slightly significant change (p < 0.05) in phytochemical content and antioxidant activity with zero order degradation. The results of this study could be concluded that R. kerrii flower was a promising natural source of strong antioxidant compounds.

A macroevolutionary explanation for energy equivalence in the scaling of body size and population density.

PubMed

Damuth, John

2007-05-01

Across a wide array of animal species, mean population densities decline with species body mass such that the rate of energy use of local populations is approximately independent of body size. This "energetic equivalence" is particularly evident when ecological population densities are plotted across several or more orders of magnitude in body mass and is supported by a considerable body of evidence. Nevertheless, interpretation of the data has remained controversial, largely because of the difficulty of explaining the origin and maintenance of such a size-abundance relationship in terms of purely ecological processes. Here I describe results of a simulation model suggesting that an extremely simple mechanism operating over evolutionary time can explain the major features of the empirical data. The model specifies only the size scaling of metabolism and a process where randomly chosen species evolve to take resource energy from other species. This process of energy exchange among particular species is distinct from a random walk of species abundances and creates a situation in which species populations using relatively low amounts of energy at any body size have an elevated extinction risk. Selective extinction of such species rapidly drives size-abundance allometry in faunas toward approximate energetic equivalence and maintains it there.

Toxicology and carcinogenesis studies of sodium dichromate dihydrate (Cas No. 7789-12-0) in F344/N rats and B6C3F1 mice (drinking water studies).

PubMed

2008-07-01

Sodium dichromate dihydrate is one of a number of inorganic compounds containing hexavalent chromium (Cr VI) found in drinking water source supplies as a contaminant resulting from various industrial processes including electroplating operations, leather tanning, and textile manufacturing. Because of the lack of adequate experimental data on the toxicity and carcinogenicity of hexavalent chromium ingested orally and because hexavalent chromium has been found in drinking water source supplies, the California Congressional Delegation, the California Environmental Protection Agency, and the California Department of Health Services nominated hexavalent chromium to the National Toxicology Program for study. Results of 3 month toxicity studies in F344/N rats and B6C3F1, BALB/c, and am3-C57BL/6 mice were reported earlier in NTP Toxicity Report 72. In the current study, male and female F344/N rats and B6C3F1 mice were exposed to sodium dichromate dihydrate (greater than 99.7% pure) in drinking water for 2 years. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to drinking water containing 0, 14.3, 57.3, 172, or 516 mg/L sodium dichromate dihydrate (equivalent to 0, 5, 20, 60, or 180 mg/L chromium) for 2 years (equivalent to average daily doses of approximately 0.6, 2.2, 6, or 17 mg sodium dichromate dihydrate/kg body weight for males and 0.7, 2.7, 7, or 20 mg/kg for females). Survival of exposed groups was similar to that of the control groups. Mean body weights of 516 mg/L males and females were less than those of the controls throughout the study. The lower body weights were partly attributed to poor palatability of the dosed water and consequent reductions in water consumption. Water consumption by 172 and 516 mg/L rats was less than that by the controls throughout the study. Exposure to sodium dichromate dihydrate caused a microcytic hypochromic anemia in rats that ameliorated with time. Exposure to sodium dichromate dihydrate resulted in the development of neoplasms of the squamous epithelium that lines the oral mucosa and tongue. The incidences of squamous cell carcinoma in the oral mucosa of 516 mg/L male and female rats were significantly greater than those in the controls. The incidence in 172 mg/L females exceeded the historical control ranges for drinking water studies and for all routes of administration. The incidences of squamous cell papilloma or squamous cell carcinoma (combined) of the oral mucosa or tongue of 516 mg/L male and female rats were significantly greater than those in the controls. Exposure concentration-related nonneoplastic liver lesions were observed in males and females exposed to 57.3 mg/L or greater. These included histiocytic cellular infiltration, chronic inflammation, fatty change (females), basophilic focus (males), and clear cell focus (females). Increased incidences of histiocytic cellular infiltration also occurred in the small intestine (duodenum), mesenteric lymph node, and pancreatic lymph node of males and/or females exposed to 57.3 mg/L or greater. 2-YEAR STUDY IN MICE: Groups of 50 male mice were exposed to drinking water containing 0, 14.3, 28.6, 85.7, or 257.4 mg/L sodium dichromate dihydrate (equivalent to 0, 5, 10, 30, or 90 mg/L chromium) for 2 years (equivalent to average daily doses of approximately 1.1, 2.6, 7, or 17 mg sodium dichromate dihydrate/kg body weight). Groups of 50 female mice were exposed to drinking water containing 0, 14.3, 57.3, 172, or 516 mg/L sodium dichromate dihydrate (equivalent to 0, 5, 20, 60, or 180 mg/L chromium) for 2 years (equivalent to average daily doses of approximately 1.1, 3.9, 9, or 25 mg/kg). Survival of exposed groups was similar to that of the control groups. Mean body weights of 257.4 mg/L males were less than those of controls from months 2 through 6 of the study, but by the end of the study, the mean body weight of 257.4 mg/L males was only slightly less than that of the control group. Mean body weights of 172 mg/L females were less than those of the controls from months 3 through 12 of the study, and mean body weights of 516 mg/L females were less than those of the controls from month 2 until the end of the study. By the end of the study, the mean body weight of 172 mg/L females was 8% less than that of the controls, and the mean body weight of 516 mg/L females was 15% less than that of the controls. The lower body weights were partly attributed to poor palatability of the dosed water and consequent reductions in water consumption. Water consumption by 85.7 and 257.4 mg/L males and 172 and 516 mg/L females was less than that by the controls throughout the study. A treatment-related microcytosis occurred in exposed mice; the mice were less affected than the rats. The incidences of neoplasms of the small intestine (duodenum, jejunum, or ileum) were increased in exposed groups of male and female mice. The incidences of adenoma of the duodenum in 257.4 mg/L males and 172 and 516 mg/L females were significantly greater than those in the controls. The incidence of carcinoma of the duodenum was significantly increased in 516 mg/L females. The incidence of adenoma of the jejunum in 516 mg/L females was significantly increased compared to that in the controls. When the incidences of adenoma and carcinoma were combined for all sites of the small intestine, the incidences were significantly increased in 85.7 and 257.4 mg/L males and 172 and 516 mg/L females compared to those in the controls. The incidences in 57.3 mg/L females exceeded the historical control ranges for drinking water studies and for all routes of administration. The incidences of diffuse epithelial hyperplasia were significantly increased in the duodenum of all exposed groups of male and female mice. The incidences of histiocytic cellular infiltration were significantly increased in the duodenum of 85.7 and 257.4 mg/L males and in 172 and 516 mg/L females. In the jejunum, the incidences of diffuse epithelial hyperplasia and histiocytic cellular infiltration were significantly increased in 516 mg/L females. The incidences of histiocytic cellular infiltration of the liver in all exposed groups of females, of the mesenteric lymph node in all exposed groups of males and females, and of the pancreatic lymph node of 85.7 and 257.4 mg/L males and 172 and 516 mg/L females were significantly increased. Tissue distribution studies showed that total chromium concentrations tended to increase with increasing exposure concentration and duration of exposure. Under the conditions of these 2-year drinking water studies, there was clear evidence of carcinogenic activity of sodium dichromate dihydrate in male and female F344/N rats based on increased incidences of squamous cell neoplasms of the oral cavity. There was clear evidence of carcinogenic activity of sodium dichromate dihydrate in male and female B6C3F1 mice based on increased incidences of neoplasms of the small intestine (duodenum, jejunum, or ileum). Exposure to sodium dichromate dihydrate resulted in histiocytic cellular infiltration in the liver, small intestine, and pancreatic and mesenteric lymph nodes of rats and mice and diffuse epithelial hyperplasia in the small intestine of male and female mice.

Radiative properties of flame-generated soot

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

Koeylue, U.O.; Faeth, G.M.

1993-05-01

Approximate methods for estimating the optical properties of flame-generated soot aggregates were evaluated using existing computer simulations and measurements in the visible and near-infrared portions of the spectrum. The following approximate methods were evaluated for both individual aggregates and polydisperse aggregate populations: the Rayleigh scattering approximation, Mie scattering for an equivalent sphere, and Rayleigh-Debye-Gans (R-D-G) scattering for both given and fractal aggregates. Results of computer simulations involved both prescribed aggregate geometry and numerically generated aggregates by cluster-cluster aggregation; multiple scattering was considered exactly using the mean-field approximation, and ignored using the R-D-G approximation. Measurements involved the angular scattering properties ofmore » soot in the postflame regions of both premixed and nonpremixed flames. The results show that available computer simulations and measurements of soot aggregate optical properties are not adequate to provide a definitive evaluation of the approximate prediction methods. 40 refs., 7 figs., 1 tab.« less

On the Health Risk of the Lumbar Spine due to Whole-Body VIBRATION—THEORETICAL Approach, Experimental Data and Evaluation of Whole-Body Vibration

NASA Astrophysics Data System (ADS)

Seidel, H.; Blüthner, R.; Hinz, B.; Schust, M.

1998-08-01

The guidance on the effects of vibration on health in standards for whole-body vibration (WBV) does not provide quantitative relationships between WBV and health risk. The paper aims at the elucidation of exposure-response relationships. An analysis of published data on the static and dynamic strength of vertebrae and bone, loaded with various frequencies under different conditions, provided the basis for a theoretical approach to evaluate repetitive loads on the lumbar spine (“internal loads”). The approach enabled the calculation of “equivalent”—with respect to cumulative fatigue failure—combinations of amplitudes and numbers of internal cyclic stress. In order to discover the relation between external peak accelerations at the seat and internal peak loads, biodynamic data of experiments (36 subjects, three somatotypes, two different postures—relaxed and bent forward; random WBV,aw, r.m.s. 1·4 ms-2, containing high transients) were used as input to a biomechanical model. Internal pressure changes were calculated using individual areas of vertebral endplates. The assessment of WBV was based on the quantitative relations between peak accelerations at the seat and pressures predicted for the disk L5/S1. For identical exposures clearly higher rates of pressure rise in the bent forward compared to the relaxed posture were predicted. The risk assessment for internal forces considered the combined internal static and dynamic loads, in relation to the predicted individual strength, and Miner's hypothesis. For exposure durations between 1 min and 8 h, energy equivalent vibration magnitudes (formula B.1, ISO 2631-1, 1997) and equivalent vibration magnitudes according to formula B.2 (time dependence over-energetic) were compared with equivalent combinations of upward peak accelerations and exposure durations according to predicted cumulative fatigue failures of lumbar vertebrae. Formula B.1 seems to underestimate the health risk caused by high magnitudes, formula B.2 is recommended for the evaluation of such conditions.

Beyond bricks and mortar: a rural network approach to preclinical medical education.

PubMed

Myhre, Douglas L; Adamiak, Paul; Turley, Nathan; Spice, Ron; Woloschuk, Wayne

2014-08-09

Countries with expansive rural regions often experience an unequal distribution of physicians between rural and urban communities. A growing body of evidence suggests that the exposure to positive rural learning experiences has an influence on a physician's choice of practice location. Capitalizing on this observation, many medical schools have developed approaches that integrate rural exposure into their curricula during clerkship. It is postulated that a preclinical rural exposure may also be effective. However, to proceed further in development, accreditation requirements must be considered. In this investigation, academic equivalence between a preclinical rural community based teaching method and the established education model was assessed. Two separate preclinical courses from the University of Calgary's three year Undergraduate Medical program were taught at two different rural sites in 2010 (11 students) and 2012 (12 students). The same academic content was delivered in the pilot sites as in the main teaching centre. To ensure consistency of teaching skills, faculty development was provided at each pilot site. Academic equivalence between the rural based learners and a matched cohort at the main University of Calgary site was determined using course examination scores, and the quality of the experience was evaluated through learner feedback. In both pilot courses there was no significant difference between examination scores of the rural distributed learners and the learners at the main University of Calgary site (p > 0.05). Feedback from the participating students demonstrated that the preceptors were very positively rated and, relative to the main site, the small group learning environment appeared to provide strengthened social support. These results suggest that community distributed education in pre-clerkship may offer academically equivalent training to existing traditional medical school curricula while also providing learners with positive rural social learning environments. The approach described may offer the potential to increase exposure to rural practice without the cost of constructing additional physical learning sites.

Class dependency of fuzzy relational database using relational calculus and conditional probability

NASA Astrophysics Data System (ADS)

Deni Akbar, Mohammad; Mizoguchi, Yoshihiro; Adiwijaya

2018-03-01

In this paper, we propose a design of fuzzy relational database to deal with a conditional probability relation using fuzzy relational calculus. In the previous, there are several researches about equivalence class in fuzzy database using similarity or approximate relation. It is an interesting topic to investigate the fuzzy dependency using equivalence classes. Our goal is to introduce a formulation of a fuzzy relational database model using the relational calculus on the category of fuzzy relations. We also introduce general formulas of the relational calculus for the notion of database operations such as ’projection’, ’selection’, ’injection’ and ’natural join’. Using the fuzzy relational calculus and conditional probabilities, we introduce notions of equivalence class, redundant, and dependency in the theory fuzzy relational database.

Reliability of equivalent sphere model in blood-forming organ dose estimation

NASA Technical Reports Server (NTRS)

Shinn, Judy L.; Wilson, John W.; Nealy, John E.

1990-01-01

The radiation dose equivalents to blood-forming organs (BFO's) of the astronauts at the Martian surface due to major solar flare events are calculated using the detailed body geometry of Langley and Billings. The solar flare spectra of February 1956, November 1960, and August 1972 events are employed instead of the idealized Webber form. The detailed geometry results are compared with those based on the 5-cm sphere model which was used often in the past to approximate BFO dose or dose equivalent. Larger discrepancies are found for the later two events possibly due to the lower numbers of highly penetrating protons. It is concluded that the 5-cm sphere model is not suitable for quantitative use in connection with future NASA deep-space, long-duration mission shield design studies.

Contribution of internal exposures to the radiological consequences of the Chernobyl accident.

PubMed

Balonov, M I; Anspaugh, L R; Bouville, A; Likhtarev, I A

2007-01-01

The main pathways leading to exposure of members of the general public due to the Chernobyl accident were external exposure from radionuclides deposited on the ground and ingestion of contaminated terrestrial food products. The collective dose to the thyroid was nearly 1.5 million man Gy in Belarus, Russia and Ukraine with nearly half received by children and adolescents. The collective effective dose received in 1986-2005 by approximately five million residents living in the affected areas of the three countries was approximately 50,000 man Sv with approximately 40% from ingestion. That contribution might have been larger if countermeasures had not been applied. The main radionuclide contributing to both external and internal effective dose is 137Cs with smaller contributions of 134Cs and 90Sr and negligible contribution of transuranic elements. The major demonstrated radiation-caused health effect of the Chernobyl accident has been an elevated incidence of thyroid cancer in children.

Fluctuation and reproducibility of exposure and effect of insulin glargine in healthy subjects.

PubMed

Becker, R H A; Frick, A D; Teichert, L; Nosek, L; Heinemann, L; Heise, T; Rave, K

2008-11-01

Low diurnal fluctuation and high day-to-day reproducibility in exposure and effect characterize beneficial basal insulin products. Two insulin glargine (LANTUS) formulations [without (R) or with polysorbate-20 (T)], added to minimize unfolding of proteins and subsequent formation of fibril structures, were assessed for equivalence in exposure and effect, and aspects of fluctuation and reproducibility in time-concentration and time-action profiles. A dose of 0.4 U/kg was subcutaneously administered to 24 healthy subjects in a two-sequence (R-T-R-T or T-R-T-R), randomized, four-way crossover trial utilizing 30-h Biostator-based euglycaemic glucose clamps. Identical serum insulin glargine concentration and time-action profiles established average, individual and population equivalence in insulin exposure and effect. Point estimates for 24-h area under the curve for insulin (INS-AUC(0-24) (h)) and glucose infusion rates (GIR-AUC(0-24) (h)) were 97% [90% confidence interval (CI): 91-103%] and 100% (88-114%), respectively. Within-subject variability (coefficient of variation) for INS-AUC(0-24) (h) and GIR-AUC(0-24) (h) were 19% (95% CI: 14-25%) and 34% (24-43%), respectively. The diurnal relative fluctuation of the serum insulin glargine concentration was 20% (95% CI: 19-21%). Insulin glargine in either formulation presents with a high day-to-day reproducibility of a uniform release after injection enabling an effective basal insulin supplementation.

Assessment of toxic potency of complex mixtures of PAHs from Lincoln Creek, Milwaukee, WI

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

Villeneuve, D.; Crunkilton, R.; DeVita, W.

1995-12-31

An assay of cytochrome P4501A catalytic activity in PLHC-1 fish hepatoma cells was used to evaluate the toxic potency of dialysates from triolein filled semipermeable polymeric membrane devices (SPMDS) exposed for variable durations and under various flow regimes to water from Lincoln Creek. Toxic potency was expressed as 2,3,7,8 tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ) calculated from bioassay results. Dose-dependent responses in measured ethoxyresorufin-o-deethylase (EROD) activity of PLHC-1 cells exposed to SPMD dialysates were shown. Toxic potency of dialysates, expressed as bioassay derived TCDD equivalents, increased with duration of SPMD exposure in Lincoln Creek from 2.0 pg/uL for a 2 day exposure tomore » 19.5 pg/uL for a 30 day exposure. This corresponded to an increase in dialysate polycyclic aromatic hydrocarbon (PAH) concentration from 8.82 ug/g after a 2 day exposure to 24.14 ug/g after 30 days. Dialysates from SPMDs exposed to Lincoln Creek stormflow had higher toxic potencies and total PAH concentrations than those exposed to baseflow only, These results suggest that levels of PAH contamination, particularly those associated with stormflow, in Lincoln Creek have potential to accumulate in fish to levels significant enough to elicit a measurable biological response (cytochrome P4501 A induction) at a potency level approaching 0.08% that of TCDD.« less

The toxicity of aluminium in humans.

PubMed

Exley, C

2016-06-01

We are living in the 'aluminium age'. Human exposure to aluminium is inevitable and, perhaps, inestimable. Aluminium's free metal cation, Alaq(3+), is highly biologically reactive and biologically available aluminium is non-essential and essentially toxic. Biologically reactive aluminium is present throughout the human body and while, rarely, it can be acutely toxic, much less is understood about chronic aluminium intoxication. Herein the question is asked as to how to diagnose aluminium toxicity in an individual. While there are as yet, no unequivocal answers to this problem, there are procedures to follow to ascertain the nature of human exposure to aluminium. It is also important to recognise critical factors in exposure regimes and specifically that not all forms of aluminium are toxicologically equivalent and not all routes of exposure are equivalent in their delivery of aluminium to target sites. To ascertain if Alzheimer's disease is a symptom of chronic aluminium intoxication over decades or breast cancer is aggravated by the topical application of an aluminium salt or if autism could result from an immune cascade initiated by an aluminium adjuvant requires that each of these is considered independently and in the light of the most up to date scientific evidence. The aluminium age has taught us that there are no inevitabilities where chronic aluminium toxicity is concerned though there are clear possibilities and these require proving or discounting but not simply ignored. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

High-throughput PBPK and Microdosimetry: Cell-level Exposures in a Virtual Tissue Context (WC9)

EPA Science Inventory

Toxicokinetic (TK) models can determine whether chemical exposures produce potentially hazardous tissue concentrations. Tissue microdosimetry TK models relate whole-body chemical exposures to cell-scale concentrations. As a proof of concept, we approximated the micro-anatomic arc...

The impact of ergonomic work environment exposures on the risk of disability pension: Prospective results from DWECS/DREAM.

PubMed

Labriola, Merete; Feveile, Helene; Christensen, Karl B; Strøyer, Jesper; Lund, Thomas

2009-11-01

The objectives were to identify the impact of ergonomic work environment exposures on the risk of disability pension. A representative sample of 8475 employees of the total working population in Denmark were interviewed regarding work environment exposures and followed in a national register with data on granted disability pension. For women, approximately 34% of the disability pension cases were attributable to ergonomic work environment exposures. For men, 21% of the disability pension cases were attributable to ergonomic work environment. Ergonomic work environment, especially physically demanding work, working with hands lifted and repetitive work, are areas of intervention at the workplace that can facilitate and prolong labour market participation. The study provides estimates for the association between ergonomic exposures at work and administrative, cost-related measures of work disability in a large population-based longitudinal cohort study over 14 years. Approximately 21% for men and 34% for women of the disability pension cases were attributable to ergonomic work environment exposures.

Documents for Recommended Toxicity Equivalency Factors for Human Health Risk Assessments of Dioxin and Dioxin-Like Compounds

EPA Pesticide Factsheets

This document describes the U.S. Environmental Protection Agency’s (U.S. EPA’s) updated approach for evaluating the human health risks from exposures to environmental media containing dioxin-like compounds (DLCs).

High-Throughput Physiologically Based Toxicokinetic Models for ToxCast Chemicals

EPA Science Inventory

Physiologically based toxicokinetic (PBTK) models aid in predicting exposure doses needed to create tissue concentrations equivalent to those identified as bioactive by ToxCast. We have implemented four empirical and physiologically-based toxicokinetic (TK) models within a new R ...

A simple calculation method for determination of equivalent square field.

PubMed

Shafiei, Seyed Ali; Hasanzadeh, Hadi; Shafiei, Seyed Ahmad

2012-04-01

Determination of the equivalent square fields for rectangular and shielded fields is of great importance in radiotherapy centers and treatment planning software. This is accomplished using standard tables and empirical formulas. The goal of this paper is to present a formula based on analysis of scatter reduction due to inverse square law to obtain equivalent field. Tables are published by different agencies such as ICRU (International Commission on Radiation Units and measurements), which are based on experimental data; but there exist mathematical formulas that yield the equivalent square field of an irregular rectangular field which are used extensively in computation techniques for dose determination. These processes lead to some complicated and time-consuming formulas for which the current study was designed. In this work, considering the portion of scattered radiation in absorbed dose at a point of measurement, a numerical formula was obtained based on which a simple formula was developed to calculate equivalent square field. Using polar coordinate and inverse square law will lead to a simple formula for calculation of equivalent field. The presented method is an analytical approach based on which one can estimate the equivalent square field of a rectangular field and may be used for a shielded field or an off-axis point. Besides, one can calculate equivalent field of rectangular field with the concept of decreased scatter radiation with inverse square law with a good approximation. This method may be useful in computing Percentage Depth Dose and Tissue-Phantom Ratio which are extensively used in treatment planning.

Environmental consequences of postulate plutonium releases from Atomics International's Nuclear Materials Development Facility (NMDF), Santa Susana, California, as a result of severe natural phenomena

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

Jamison, J.D.; Watson, E.C.

1982-02-01

Potential environmental consequences in terms of radiation dose to people are presented for postulated plutonium releases caused by severe natural phenomena at the Atomics International's Nuclear Materials Development Facility (NMDF), in the Santa Susana site, California. The severe natural phenomena considered are earthquakes, tornadoes, and high straight-line winds. Plutonium deposition values are given for significant locations around the site. All important potential exposure pathways are examined. The most likely 50-year committed dose equivalents are given for the maximum-exposed individual and the population within a 50-mile radius of the plant. The maximum plutonium deposition values likely to occur offsite are alsomore » given. The most likely calculated 50-year collective committed dose equivalents are all much lower than the collective dose equivalent expected from 50 years of exposure to natural background radiation and medical x-rays. The most likely maximum residual plutonium contamination estimated to be deposited offsite following the earthquake, and the 150-mph and 170-mph tornadoes are above the Environmental Protection Agency's (EPA) proposed guideline for plutonium in the general environment of 0.2 ..mu..Ci/m/sup 2/. The deposition values following the 110-mph and the 130-mph tornadoes are below the EPA proposed guideline.« less

Environmental consequences of postulated plutonium releases from General Electric Company Vallecitos Nuclear Center, Vallecitos, California, as a result of severe natural phenomena

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

Jamison, J.D.; Watson, E.C.

1980-11-01

Potential environmental consequences in terms of radiation dose to people are presented for postulated plutonium releases caused by severe natural phenomena at the General Electric Company Vallecitos Nuclear Center, Vallecitos, California. The severe natural phenomena considered are earthquakes, tornadoes, and high straight-line winds. Maximum plutonium deposition values are given for significant locations around the site. All important potential exposure pathways are examined. The most likely 50-year committed dose equivalents are given for the maximum-exposed individual and the population within a 50-mile radius of the plant. The maximum plutonium deposition values likely to occur offsite are also given. The most likelymore » calculated 50-year collective committed dose equivalents are all much lower than the collective dose equivalent expected from 50 years of exposure to natural background radiation and medical x-rays. The most likely maximum residual plutonium contamination estimated to be deposited offsite following the earthquakes, and the 180-mph and 230-mph tornadoes are above the Environmental Protection Agency's (EPA) proposed guideline for plutonium in the general environment of 0.2 ..mu..Ci/m/sup 2/. The deposition values following the 135-mph tornado are below the EPA proposed guidelines.« less

Development of an effective dose coefficient database using a computational human phantom and Monte Carlo simulations to evaluate exposure dose for the usage of NORM-added consumer products.

PubMed

Yoo, Do Hyeon; Shin, Wook-Geun; Lee, Jaekook; Yeom, Yeon Soo; Kim, Chan Hyeong; Chang, Byung-Uck; Min, Chul Hee

2017-11-01

After the Fukushima accident in Japan, the Korean Government implemented the "Act on Protective Action Guidelines Against Radiation in the Natural Environment" to regulate unnecessary radiation exposure to the public. However, despite the law which came into effect in July 2012, an appropriate method to evaluate the equivalent and effective doses from naturally occurring radioactive material (NORM) in consumer products is not available. The aim of the present study is to develop and validate an effective dose coefficient database enabling the simple and correct evaluation of the effective dose due to the usage of NORM-added consumer products. To construct the database, we used a skin source method with a computational human phantom and Monte Carlo (MC) simulation. For the validation, the effective dose was compared between the database using interpolation method and the original MC method. Our result showed a similar equivalent dose across the 26 organs and a corresponding average dose between the database and the MC calculations of < 5% difference. The differences in the effective doses were even less, and the result generally show that equivalent and effective doses can be quickly calculated with the database with sufficient accuracy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inter-Individual Variability in High-Throughput Risk ...

EPA Pesticide Factsheets

We incorporate realistic human variability into an open-source high-throughput (HT) toxicokinetics (TK) modeling framework for use in a next-generation risk prioritization approach. Risk prioritization involves rapid triage of thousands of environmental chemicals, most which have little or no existing TK data. Chemicals are prioritized based on model estimates of hazard and exposure, to decide which chemicals should be first in line for further study. Hazard may be estimated with in vitro HT screening assays, e.g., U.S. EPA’s ToxCast program. Bioactive ToxCast concentrations can be extrapolated to doses that produce equivalent concentrations in body tissues using a reverse TK approach in which generic TK models are parameterized with 1) chemical-specific parameters derived from in vitro measurements and predicted from chemical structure; and 2) with physiological parameters for a virtual population. Here we draw physiological parameters from realistic estimates of distributions of demographic and anthropometric quantities in the modern U.S. population, based on the most recent CDC NHANES data. A Monte Carlo approach, accounting for the correlation structure in physiological parameters, is used to estimate ToxCast equivalent doses for the most sensitive portion of the population. To quantify risk, ToxCast equivalent doses are compared to estimates of exposure rates based on Bayesian inferences drawn from NHANES urinary analyte biomonitoring data. The inclusion

Humidity and Gravimetric Equivalency Adjustments for Nephelometer-Based Particulate Matter Measurements of Emissions from Solid Biomass Fuel Use in Cookstoves

PubMed Central

Soneja, Sutyajeet; Chen, Chen; Tielsch, James M.; Katz, Joanne; Zeger, Scott L.; Checkley, William; Curriero, Frank C.; Breysse, Patrick N.

2014-01-01

Great uncertainty exists around indoor biomass burning exposure-disease relationships due to lack of detailed exposure data in large health outcome studies. Passive nephelometers can be used to estimate high particulate matter (PM) concentrations during cooking in low resource environments. Since passive nephelometers do not have a collection filter they are not subject to sampler overload. Nephelometric concentration readings can be biased due to particle growth in high humid environments and differences in compositional and size dependent aerosol characteristics. This paper explores relative humidity (RH) and gravimetric equivalency adjustment approaches to be used for the pDR-1000 used to assess indoor PM concentrations for a cookstove intervention trial in Nepal. Three approaches to humidity adjustment performed equivalently (similar root mean squared error). For gravimetric conversion, the new linear regression equation with log-transformed variables performed better than the traditional linear equation. In addition, gravimetric conversion equations utilizing a spline or quadratic term were examined. We propose a humidity adjustment equation encompassing the entire RH range instead of adjusting for RH above an arbitrary 60% threshold. Furthermore, we propose new integrated RH and gravimetric conversion methods because they have one response variable (gravimetric PM2.5 concentration), do not contain an RH threshold, and is straightforward. PMID:24950062

Humidity and gravimetric equivalency adjustments for nephelometer-based particulate matter measurements of emissions from solid biomass fuel use in cookstoves.

PubMed

Soneja, Sutyajeet; Chen, Chen; Tielsch, James M; Katz, Joanne; Zeger, Scott L; Checkley, William; Curriero, Frank C; Breysse, Patrick N

2014-06-19

Great uncertainty exists around indoor biomass burning exposure-disease relationships due to lack of detailed exposure data in large health outcome studies. Passive nephelometers can be used to estimate high particulate matter (PM) concentrations during cooking in low resource environments. Since passive nephelometers do not have a collection filter they are not subject to sampler overload. Nephelometric concentration readings can be biased due to particle growth in high humid environments and differences in compositional and size dependent aerosol characteristics. This paper explores relative humidity (RH) and gravimetric equivalency adjustment approaches to be used for the pDR-1000 used to assess indoor PM concentrations for a cookstove intervention trial in Nepal. Three approaches to humidity adjustment performed equivalently (similar root mean squared error). For gravimetric conversion, the new linear regression equation with log-transformed variables performed better than the traditional linear equation. In addition, gravimetric conversion equations utilizing a spline or quadratic term were examined. We propose a humidity adjustment equation encompassing the entire RH range instead of adjusting for RH above an arbitrary 60% threshold. Furthermore, we propose new integrated RH and gravimetric conversion methods because they have one response variable (gravimetric PM2.5 concentration), do not contain an RH threshold, and is straightforward.

Risk assessment of combined exposure to alkenylbenzenes through consumption of plant food supplements containing parsley and dill.

PubMed

Alajlouni, Abdalmajeed M; Al-Malahmeh, Amer J; Wesseling, Sebastiaan; Kalli, Marina; Vervoort, Jacques; Rietjens, Ivonne M C M

2017-12-01

A risk assessment was performed of parsley- and dill-based plant food supplements (PFS) containing apiol and related alkenylbenzenes. First, the levels of the alkenylbenzenes in the PFS and the resulting estimated daily intake (EDI) resulting from use of the PFS were quantified. Since most PFS appeared to contain more than one alkenylbenzene, a combined risk assessment was performed based on equal potency or using a so-called toxic equivalency (TEQ) approach based on toxic equivalency factors (TEFs) for the different alkenylbenzenes. The EDIs resulting from daily PFS consumption amount to 0.74-125 µg kg -1 bw for the individual alkenylbenzenes, 0.74-160 µg kg -1 bw for the sum of the alkenylbenzenes, and 0.47-64 µg kg -1 bw for the sum of alkenylbenzenes when expressed in safrole equivalents. The margins of exposure (MOEs) obtained were generally below 10,000, indicating a priority for risk management if the PFS were to be consumed on a daily basis. Considering short-term use of the PFS, MOEs would increase above 10,000, indicating low priority for risk management. It is concluded that alkenylbenzene intake through consumption of parsley- and dill-based PFS is only of concern when these PFS are used for long periods of time.

On the homotopy equivalence of simple AI-algebras

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

Aristov, O Yu

1999-02-28

Let A and B be simple unital AI-algebras (an AI-algebra is an inductive limit of C*-algebras of the form BigOplus{sub i}{sup k}C([0,1],M{sub N{sub i}}). It is proved that two arbitrary unital homomorphisms from A into B such that the corresponding maps K{sub 0}A{yields}K{sub 0}B coincide are homotopic. Necessary and sufficient conditions on the Elliott invariant for A and B to be homotopy equivalent are indicated. Moreover, two algebras in the above class having the same K-theory but not homotopy equivalent are constructed. A theorem on the homotopy of approximately unitarily equivalent homomorphisms between AI-algebras is used in the proof, whichmore » is deduced in its turn from a generalization to the case of AI-algebras of a theorem of Manuilov stating that a unitary matrix almost commuting with a self-adjoint matrix h can be joined to 1 by a continuous path consisting of unitary matrices almost commuting with h.« less

d-Limonene-induced male rat-specific nephrotoxicity: Evaluation of the association between d-limonene and alpha 2u-globulin

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

Lehman-McKeeman, L.D.; Rodriguez, P.A.; Takigiku, R.

1989-06-15

d-Limonene is a naturally occurring monoterpene, which when dosed orally, causes a male rat-specific nephrotoxicity manifested acutely as the exacerbation of protein droplets in proximal tubule cells. Experiments were conducted to examine the retention of (/sup 14/C)d-limonene in male and female rat kidney, to determine whether d-limonene or one or more of its metabolites associates with the male rat-specific protein, alpha 2u-globulin, and if so, to identify the bound material. The results indicated that, 24 hr after oral administration of 3 mmol d-limonene/kg, the renal concentration of d-limonene equivalents was approximately 2.5 times higher in male rats than in femalemore » rats. Equilibrium dialysis in the presence or absence of sodium dodecyl sulfate indicated that approximately 40% of the d-limonene equivalents in male rat kidney associated with proteins in a reversible manner, whereas no significant association was observed between d-limonene equivalents and female rat kidney proteins. Association between d-limonene and male rat kidney proteins was characterized by high-performance gel filtration and reverse-phase chromatography. Gel filtration HPLC indicated that d-limonene in male rat kidney is associated with a protein fraction having a molecular weight of approximately 20,000. Separation of alpha 2u-globulin from other kidney proteins by reverse-phase HPLC indicated that d-limonene associated with a protein present only in male rat kidney which was definitively identified as alpha 2u-globulin by amino acid sequencing. The major metabolite associated with alpha 2u-globulin was d-limonene-1,2-oxide. Parent d-limonene was also identified as a minor component in the alpha 2u-globulin fraction.« less

Organochlorine contaminants in double-crested cormorants from Green Bay, Wisconsin: II. Effects of an extract derived from cormorant eggs on the chicken embryo

USGS Publications Warehouse

Powell, D.C.; Aulerich, R.J.; Meadows, J.C.; Tillitt, D.E.; Stromborg, K.L.; Kubiak, T.J.; Giesy, J.P.; Bursian, S.J.

1997-01-01

White Leghorn chicken (Gallus domesticus) eggs were injected prior to incubation with one of four concentrations (0.001, 0.01, 0.1, and 1.0 egg-equivalent) of an extract derived from 1,000 double-crested cormorant (Phalacrocorax auritus) eggs collected at Spider Island adjacent to Green Bay in Lake Michigan. One egg-equivalent corresponded to the concentration of contaminants present in an average cormorant egg. This was approximately 322 pg toxic equivalents (TEQs)/g, ww egg with polychlorinatedbiphenyl congener 126 (3,3′,4,4′,5-pentachlorobiphenyl) accounting for over 70% of the TEQs. Injection of 1.0 egg-equivalent resulted in 77% mortality at hatch. The incidence of developmental abnormalities (structural defects or edema) was not affected by injection of the extract. Body weight gain of chicks was reduced in the 1.0 egg-equivalent dose group in the first, second, and third week's post-hatch. Relative brain weights were greater and relative bursa weights were less in the 1.0 egg-equivalent dose group than in the vehicle control at three weeks of age. There were no significant differences in the relative weights of the heart, liver, spleen, testes, or comb among treated and control birds.

Determination of ground-state hole-transfer rates between equivalent sites in oxidized multiporphyrin arrays using time-resolved optical spectroscopy.

PubMed

Song, Hee-eun; Kirmaier, Christine; Taniguchi, Masahiko; Diers, James R; Bocian, David F; Lindsey, Jonathan S; Holten, Dewey

2008-11-19

Excited-state charge separation in molecular architectures has been widely explored, yet ground-state hole (or electron) transfer, particularly involving equivalent pigments, has been far less studied, and direct quantitation of the rate of transfer often has proved difficult. Prior studies of ground-state hole transfer between equivalent zinc porphyrins using electron paramagnetic resonance techniques give a lower limit of approximately (50 ns)(-1) on the rates. Related transient optical studies of hole transfer between inequivalent sites [zinc porphyrin (Zn) and free base porphyrin (Fb)] give an upper limit of approximately (20 ps)(-1). Thus, a substantial window remains for the unknown rates of ground-state hole transfer between equivalent sites. Herein, the ground-state hole-transfer processes are probed in a series of oxidized porphyrin triads (ZnZnFb) with the focus being on determination of the rates between the nominally equivalent sites (Zn/Zn). The strategy builds upon recent time-resolved optical studies of the photodynamics of dyads wherein a zinc porphyrin is electrochemically oxidized and the attached free base porphyrin is photoexcited. The resulting energy- and hole-transfer processes in the oxidized ZnFb dyads are typically complete within 100 ps of excitation. Such processes are also present in the triads and serve as a starting point for determining the rates of ground-state hole transfer between equivalent sites in the triads. The rate constant of the Zn/Zn hole transfer is found to be (0.8 ns)(-1) for diphenylethyne-linked zinc porphyrins and increases only slightly to (0.6 ns)(-1) when a shorter phenylene linker is utilized. The rate decreases slightly to (1.1 ns)(-1) when steric constraints are introduced in the diarylethyne linker. In general, the rate constants for ground-state Zn/Zn hole transfer in oxidized arrays are a factor of 40 slower than those for Zn/Fb transfer. Collectively, the findings should aid the design of next-generation molecular architectures for applications in solar-energy conversion.

Developmental Neurotoxicity of Inhaled Ambient Ultrafine Particle Air Pollution: Parallels with Neuropathological and Behavioral Features of Autism and Other Neurodevelopmental Disorders

PubMed Central

Allen, J. L.; Oberdorster, G.; Morris-Schafer, K.; Wong, C.; Klocke, C.; Sobolewski, M.; Conrad, K.; Mayer-Proschel, M.; Cory-Slechta, D. A.

2016-01-01

Accumulating evidence from both human and animal studies show that brain is a target of air pollution. Multiple epidemiological studies have now linked components of air pollution to diagnosis of autism spectrum disorder (ASD), a linkage with plausibility based on the shared mechanisms of inflammation. Additional plausibility appears to be provided by findings from our studies in mice of exposures from postnatal day (PND) 4-7 and 10-13 (human 3rd trimester equivalent), to concentrated ambient ultrafine (UFP) particles, considered the most reactive component of air pollution, at levels consistent with high traffic areas of major U.S. cities and thus highly relevant to human exposures. These exposures, occurring during a period of marked neuro- and gliogenesis, unexpectedly produced a pattern of developmental neurotoxicity notably similar to multiple hypothesized mechanistic underpinnings of ASD, including its greater impact in males. UFP exposures induced inflammation/microglial activation, reductions in size of the corpus callosum (CC) and associated hypomyelination, aberrant white matter development and/or structural integrity with ventriculomegaly (VM), elevated glutamate and excitatory/inhibitory imbalance, increased amygdala astrocytic activation, and repetitive and impulsive behaviors. Collectively, these findings suggest the human 3rd trimester equivalent as a period of potential vulnerability to neurodevelopmental toxicity to UFP, particularly in males, and point to the possibility that UFP air pollution exposure during periods of rapid neuro- and gliogenesis may be a risk factor not only for ASD, but also for other neurodevelopmental disorders that share features with ASD, such as schizophrenia, attention deficit disorder, and periventricular leukomalacia. PMID:26721665

The cyclophosphamide equivalent dose as an approach for quantifying alkylating agent exposure: a report from the Childhood Cancer Survivor Study.

PubMed

Green, Daniel M; Nolan, Vikki G; Goodman, Pamela J; Whitton, John A; Srivastava, DeoKumar; Leisenring, Wendy M; Neglia, Joseph P; Sklar, Charles A; Kaste, Sue C; Hudson, Melissa M; Diller, Lisa R; Stovall, Marilyn; Donaldson, Sarah S; Robison, Leslie L

2014-01-01

Estimation of the risk of adverse long-term outcomes such as second malignant neoplasms and infertility often requires reproducible quantification of exposures. The method for quantification should be easily utilized and valid across different study populations. The widely used Alkylating Agent Dose (AAD) score is derived from the drug dose distribution of the study population and thus cannot be used for comparisons across populations as each will have a unique distribution of drug doses. We compared the performance of the Cyclophosphamide Equivalent Dose (CED), a unit for quantifying alkylating agent exposure independent of study population, to the AAD. Comparisons included associations from three Childhood Cancer Survivor Study (CCSS) outcome analyses, receiver operator characteristic (ROC) curves and goodness of fit based on the Akaike's Information Criterion (AIC). The CED and AAD performed essentially identically in analyses of risk for pregnancy among the partners of male CCSS participants, risk for adverse dental outcomes among all CCSS participants and risk for premature menopause among female CCSS participants, based on similar associations, lack of statistically significant differences between the areas under the ROC curves and similar model fit values for the AIC between models including the two measures of exposure. The CED is easily calculated, facilitating its use for patient counseling. It is independent of the drug dose distribution of a particular patient population, a characteristic that will allow direct comparisons of outcomes among epidemiological cohorts. We recommend the use of the CED in future research assessing cumulative alkylating agent exposure. © 2013 Wiley Periodicals, Inc.

Cancer and non-cancer brain and eye effects of chronic low-dose ionizing radiation exposure

PubMed Central

2012-01-01

Background According to a fundamental law of radiobiology (“Law of Bergonié and Tribondeau”, 1906), the brain is a paradigm of a highly differentiated organ with low mitotic activity, and is thus radio-resistant. This assumption has been challenged by recent evidence discussed in the present review. Results Ionizing radiation is an established environmental cause of brain cancer. Although direct evidence is lacking in contemporary fluoroscopy due to obvious sample size limitation, limited follow-up time and lack of focused research, anecdotal reports of clusters have appeared in the literature, raising the suspicion that brain cancer may be a professional disease of interventional cardiologists. In addition, although terminally differentiated neurons have reduced or mild proliferative capacity, and are therefore not regarded as critical radiation targets, adult neurogenesis occurs in the dentate gyrus of the hippocampus and the olfactory bulb, and is important for mood, learning/memory and normal olfactory function, whose impairment is a recognized early biomarker of neurodegenerative diseases. The head doses involved in radiotherapy are high, usually above 2 Sv, whereas the low-dose range of professional exposure typically involves lifetime cumulative whole-body exposure in the low-dose range of < 200 mSv, but with head exposure which may (in absence of protection) arrive at a head equivalent dose of 1 to 3 Sv after a professional lifetime (corresponding to a brain equivalent dose around 500 mSv). Conclusions At this point, a systematic assessment of brain (cancer and non-cancer) effects of chronic low-dose radiation exposure in interventional cardiologists and staff is needed. PMID:22540409

DEVELOPMENT OF WEIGHTED DISTRIBUTIONS OF REPS FOR DIOXIN-LIKE COMPOUNDS

EPA Science Inventory

Potential health risks associated with exposure to mixtures of dioxin-like compounds are currently assessed using a toxic equivalency factor (TEF) approach. Recently, both the WH0 and NAS reviewed the TEF methodology and acknowledged the importance of better characterizing varia...

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

Fedorova, T.A.; Babarin, P.M.

A sharp drop of uric acid in the urine of irradiated rats begins on the second day afier exposure, and a considerable increase of allantoin ( approximates 26%) was observed the next day sfter the exposure. (R.V.J.)

Radiation exposure and risk assessment for critical female body organs

NASA Technical Reports Server (NTRS)

Atwell, William; Weyland, Mark D.; Hardy, Alva C.

1991-01-01

Space radiation exposure limits for astronauts are based on recommendations of the National Council on Radiation Protection and Measurements. These limits now include the age at exposure and sex of the astronaut. A recently-developed computerized anatomical female (CAF) model is discussed in detail. Computer-generated, cross-sectional data are presented to illustrate the completeness of the CAF model. By applying ray-tracing techniques, shield distribution functions have been computed to calculate absorbed dose and dose equivalent values for a variety of critical body organs (e.g., breasts, lungs, thyroid gland, etc.) and mission scenarios. Specific risk assessments, i.e., cancer induction and mortality, are reviewed.

Applying the Index of Watershed Integrity to the Western Balkan Region

EPA Science Inventory

In 2014, the western Balkans’ heaviest recorded rains triggered extensive flooding affecting approximately 29,600 km2, or the equivalent of 75% of the study area. Rapid urbanization and the increasing regularity of late-summer droughts in the region likely exacerbated these...

Operational Reserve: Costs and Considerations

DTIC Science & Technology

material way. Findings include relevant RC costs at approximately 132% of those of a hypothetical equivalent AC unit. The primary contributor to...the Deputy Commandant for Manpower and Reserve Affairs (DC, M and RA), should monitor the totality of relevant monetary and non -monetary costs for any

Prioritizing food safety and research

USDA-ARS?s Scientific Manuscript database

Recent publications have revealed that approximately 48 million individuals in the the United States of America contract foodborne illnesses each year, with associated costs estimated at $77.7 billion U.S. dollars (equivalent to ca. 87.5 trillion Korean won in the year 2012). The United States Depa...

Exposure to grain dust in Great Britain.

PubMed

Spankie, Sally; Cherrie, John W

2012-01-01

Airborne grain dust is a complex mixture of fragments of organic material from grain, plus mineral matter from soil, and possible insect, fungal, or bacterial contamination or their toxic products, such as endotoxin. In the 1990s, grain workers in Britain were frequently exposed to inhalable dust >10 mg.m(-3) (8 h), with particularly high exposures being found at terminals where grain was imported or exported and in drying operations (personal exposure typically approximately 20 mg.m(-3)). Since then, the industry has made substantial progress in improving the control of airborne dust through better-designed processes, increased automation, and an improved focus on product quality. We have used information from the published scientific literature and a small survey of industry representatives to estimate current exposure levels. These data suggest that current long-term exposure to inhalable dust for most workers is on average less than approximately 3 mg.m(-3), with perhaps 15-20% of individual personal exposures being >10 mg.m(-3). There are no published data from Britain on short-term exposure during cleaning and other tasks. We have estimated average levels for a range of tasks and judge that the highest levels, for example during some cleaning activities and certain process tasks such as loading and packing, are probably approximately10 mg.m(-3). Endotoxin levels were judged likely to be <10⁴ EU m(-3) throughout the industry provided inhalable dust levels are <10 mg.m(-3). There are no published exposure data on mycotoxin, respirable crystalline silica, and mite contamination but these are not considered to present widespread problems in the British industry. Further research should be carried out to confirm these findings.

Component Performance Investigation of J71 Experimental Turbine I : Over-all Performance with 97-percent-design Stator Areas

NASA Technical Reports Server (NTRS)

Schum, Harold J; Davison, Elmer H

1956-01-01

The over-all component performance characteristics of a J71 experimental three-stage turbine with 97 percent design stator areas were determined over a range of speed and pressure ratio at inlet-air conditions of approximately 35 inches of mercury absolute and 700 degrees R. The turbine break internal efficiency at design operating conditions was 0.877; the maximum efficiency of 0.886 occurred at a pressure ratio of 4.0 at 120 percent of design equivalent rotor speed. In general, the turbine yielded a wide range of efficient operation, permitting flexibility in the choice of different modes of engine operation. Limiting blade loading of the third rotor was approached but not obtained over the range of conditions investigated herein. At the design operating point, the turbine equivalent weight flow was approximately 105 percent of design. Choking of the third-rotor blades occurred at design speed and an over-all pressure ratio of 4.2.

Understanding and Minimising Occupational Radiation in the Catheterisation Laboratory with PISAX and the ACIST CVi® Contrast Delivery System

PubMed Central

Bar, Olivier

2013-01-01

This paper provides an overview of radiation exposure and its associated risks in the cardiac catheterisation laboratory (cath lab), as well as strategies to minimise radiation exposure for operators, cath lab staff and patients. The benefits of using a mobile 2 mm lead equivalent radiation shield (PISAX) and adoption of an automated contrast injection system (the ACIST CVi® Contrast Delivery System) are discussed, and the potential advantages of their combination are reviewed. PMID:29588748

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.

Corneal and skin laser exposures from 1540-nm laser pulses

NASA Astrophysics Data System (ADS)

Johnson, Thomas E.; Mitchell, Michael A.; Rico, Pedro J.; Fletcher, David J.; Eurell, Thomas E.; Roach, William P.

2000-06-01

Mechanisms of tissue damage are investigated for skin and cornea exposures from 1540 nm ('eye safe') laser single pulses of 0.8 milli-seconds. New skin model data point out the advantages of using the Yucatan mini-pig versus the Yorkshire pig for in-vivo skin laser exposures. Major advantages found include similarities in thickness and melanin content when compared with human skin. Histology from Yucatan mini-pig skin exposures and the calculation of an initial ED50 threshold indicate that the main photon tissue interaction may not be solely due to water absorption. In-vitro corneal equivalents compared well with in-vivo rabbit cornea exposure under similar laser conditions. In-vivo and in-vitro histology show that initial energy deposition leading to damage occurs intrastromally, while epithelial cells show no direct injury due to laser light absorption.

[Multiple mere exposure effect: category evaluation measured in the Go/No-go association task (GNAT)].

PubMed

Kawakami, Naoaki; Yoshida, Fujio

2011-12-01

The effect on likability of multiple subliminal exposures to the same person was investigated. Past studies on the mere exposure effect indicated a correlation between the frequency of repeated exposure to the same stimulus and likability. We proposed that exposure to various stimuli of the same person would have a stronger effect on likability. Participants were subliminally exposed to photographs of a person's face taken from seven angles (multi-angle-exposure) three times each (Experiment 1), or photographs of a person with seven facial expressions (multi-expression-exposure) three times each (Experiment 2). Then, the likability toward the exposed person was measured using the Go/No-go Association Task. The results indicated that the effect of the multiple exposures from various angles was equivalent to exposure to only one full-face photograph shown 21 times (Experiment 1). Moreover, likability was significantly higher in the case of exposure to various facial expressions than for exposure to only a single facial expression (Experiment 2). The results suggest that exposure to various stimuli in a category is more effective than repeated exposure to a single stimulus for increasing likability.

Comparison of a suspended radiation protection system versus standard lead apron for radiation exposure of a simulated interventionalist.

PubMed

Marichal, Daniel A; Anwar, Temoor; Kirsch, David; Clements, Jessica; Carlson, Luke; Savage, Clare; Rees, Chet R

2011-04-01

To evaluate the radiation protective characteristics of a system designed to enhance operator protection while eliminating weight to the body and allowing freedom of motion. Radiation doses to a mock interventionalist were measured with calibrated dosimeters in a clinical interventional suite. A standard lead apron (SLA; Pb equivalent, 0.5 mm) was compared with a suspended radiation protection system (ZeroGravity; Zgrav) that shields from the top of the head to the calves (except the right arm and left forearm) with a complex overhead motion system that eliminates weight on the operator and allows freedom of motion. Zgrav included a suspended lead apron with increased lead equivalency, greater length, proximal left arm and shoulder coverage, and a wraparound face shield of 0.5 mm Pb equivalency. A 26-cm-thick Lucite stack (ie, mock patient) created scatter during 10 controlled angiography sequences of 120 exposures each. Parameters included a field of view of 40 cm, table height of 94 cm, 124 cm from the tube to image intensifier, 50 cm from the image center to operator, 66 kVp, and 466-470 mA. Under identical conditions, average doses (SLA vs Zgrav) were 264 versus 3.4 (ratio, 78) to left axilla (P < .001), 456 versus 10.2 (ratio, 45) to left eye (P < .001), 379.4 versus 6.6 (ratio, 57) to right eye (P < .005), and 18.8 versus 1.2 (ratio, 16) to gonad (P < .001). Relative to a conventional lead apron, the Zgrav system provided a 16-78-fold decrease in radiation exposure for a mock interventionalist in a simulated clinical setting. Copyright © 2011 SIR. Published by Elsevier Inc. All rights reserved.

Sedimentology and taphonomy of the upper Karoo-equivalent Mpandi Formation in the Tuli Basin of Zimbabwe, with a new 40Ar/ 39Ar age for the Tuli basalts

NASA Astrophysics Data System (ADS)

Rogers, Raymond R.; Rogers, Kristina Curry; Munyikwa, Darlington; Terry, Rebecca C.; Singer, Bradley S.

2004-10-01

Karoo-equivalent rocks in the Tuli Basin of Zimbabwe are described, with a focus on the dinosaur-bearing Mpandi Formation, which correlates with the Elliot Formation (Late Triassic-Early Jurassic) in the main Karoo Basin. Isolated exposures of the Mpandi Formation along the banks of the Limpopo River consist of red silty claystones and siltstones that preserve root traces, small carbonate nodules, and hematite-coated prosauropod bones. These fine-grained facies accumulated on an ancient semi-arid floodplain. Widespread exposures of quartz-rich sandstone and siltstone representing the upper Mpandi Formation crop out on Sentinel Ranch. These strata preserve carbonate concretions and silicified root casts, and exhibit cross-bedding indicative of deposition via traction currents, presumably in stream channels. Prosauropod fossils are also preserved in the Sentinel Ranch exposures, with one particularly noteworthy site characterized by a nearly complete and articulated Massospondylus individual. An unconformity caps the Mpandi Formation in the study area, and this stratigraphically significant surface rests on a laterally-continuous zone of pervasive silicification interpreted as a silcrete. Morphologic, petrographic, and geochemical data indicate that the Mpandi silcrete formed by intensive leaching near the ground surface during prolonged hiatus. Chert clasts eroded from the silcrete are intercalated at the base of the overlying Samkoto Formation (equivalent to the Clarens Formation in the main Karoo Basin), which in turn is overlain by the Tuli basalts. These basalts, which are part of the Karoo Igneous Province, yield a new 40Ar/ 39Ar plateau age of 186.3 ± 1.2 Ma.

Equivalent background speed in recovery from motion adaptation.

PubMed

Simpson, W A; Newman, A; Aasland, W

1997-01-01

We measured, in the same observers, (1) the detectability, d, of a small rotational jump following adaptation to rotational motion and (2) the detectability of the same jump when superimposed on one of several background rotation speeds. Following 90 s of motion adaptation the detectability of the jump was impaired, and sensitivity slowly recovered over the course of 60 s. The detectability of the jump was also impaired by the background speed in a way consistent with a quadratic form of Weber's law. We propose that motion adaptation impairs the detectability of the small jump because it is as if an equivalent background speed has been superimposed on the display. We measured the equivalent background by finding the real background speed that produced the same d' at each instant in the recovery from motion adaptation. The equivalent background started at approximately one to two thirds the speed of the adapting motion, declined rapidly, rose to a small peak at 30 s, then disappeared by 60 s. Since the equivalent background speed corresponds to the speed of the motion aftereffect, we have measured the time course of the motion aftereffect with objective psychophysics.

High-Spatial-Resolution OH PLIF Visualization in a Cavity-Stabilized Ethylene-Air Turbulent Flame

NASA Technical Reports Server (NTRS)

Geipel, Clayton M.; Rockwell, Robert D.; Chelliah, Harsha K.; Cutler, Andrew D.; Spelker, Christopher A.; Hashem, Zeid; Danehy, Paul M.

2017-01-01

High-spatial-resolution OH planar laser-induced fluorescence was measured for a premixed ethylene-air turbulent flame in an electrically-heated Mach 2 continuous-flow facility (University of Virginia Supersonic Combustion Facility, Configuration E.) The facility comprised a Mach 2 nozzle, an isolator with flush-wall fuel injectors, a combustor with optical access, and an extender. The flame was anchored at a cavity flameholder with a backward-facing step of height 9 mm. The temperature-insensitive Q1(8) transition of OH was excited using laser light of wavelength 283.55 nm. A spatial filter was used to create a laser sheet approximately 25 microns thick based on full-width at half maximum (FWHM). Extension tubes increased the magnification of an intensified camera system, achieving in-plane resolution of 40 microns based on a 50% modulation transfer function (MTF). The facility was tested with total temperature 1200 K, total pressure 300 kPa, local fuel/air equivalence ratios of approximately 0.4, and local Mach number of approximately 0.73 in the combustor. A test case with reduced total temperature and another with reduced equivalence ratio were also tested. PLIF images were acquired along a streamwise plane bisecting the cavity flameholder, from the backward facing step to 120 mm downstream of the step. The smallest observed features in the flow had width of approximately 110 microns. Flame surface density was calculated for OH PLIF images.

On the wavelet optimized finite difference method

NASA Technical Reports Server (NTRS)

Jameson, Leland

1994-01-01

When one considers the effect in the physical space, Daubechies-based wavelet methods are equivalent to finite difference methods with grid refinement in regions of the domain where small scale structure exists. Adding a wavelet basis function at a given scale and location where one has a correspondingly large wavelet coefficient is, essentially, equivalent to adding a grid point, or two, at the same location and at a grid density which corresponds to the wavelet scale. This paper introduces a wavelet optimized finite difference method which is equivalent to a wavelet method in its multiresolution approach but which does not suffer from difficulties with nonlinear terms and boundary conditions, since all calculations are done in the physical space. With this method one can obtain an arbitrarily good approximation to a conservative difference method for solving nonlinear conservation laws.

What do we know about the effects of exposure to 'Low alcohol' and equivalent product labelling on the amounts of alcohol, food and tobacco people select and consume? A systematic review.

PubMed

Shemilt, Ian; Hendry, Vivien; Marteau, Theresa M

2017-01-12

Explicit labelling of lower strength alcohol products could reduce alcohol consumption by attracting more people to buy and drink such products instead of higher strength ones. Alternatively, it may lead to more consumption due to a 'self-licensing' mechanism. Equivalent labelling of food or tobacco (for example "Low fat" or "Low tar") could influence consumption of those products by similar mechanisms. This systematic review examined the effects of 'Low alcohol' and equivalent labelling of alcohol, food and tobacco products on selection, consumption, and perceptions of products among adults. A systematic review was conducted based on Cochrane methods. Electronic and snowball searches identified 26 eligible studies. Evidence from 12 randomised controlled trials (all on food) was assessed for risk of bias, synthesised using random effects meta-analysis, and interpreted in conjunction with evidence from 14 non-randomised studies (one on alcohol, seven on food and six on tobacco). Outcomes assessed were: quantities of the product (i) selected or (ii) consumed (primary outcomes - behaviours), (iii) intentions to select or consume the product, (iv) beliefs associated with it consumption, (v) product appeal, and (vi) understanding of the label (secondary outcomes - cognitions). Evidence for impacts on the primary outcomes (i.e. amounts selected or consumed) was overall of very low quality, showing mixed effects, likely to vary by specific label descriptors, products and population characteristics. Overall very low quality evidence suggested that exposure to 'Low alcohol' and equivalent labelling on alcohol, food and tobacco products can shift consumer perceptions of products, with the potential to 'self-licence' excess consumption. Considerable uncertainty remains about the effects of labels denoting low alcohol, and equivalent labels, on alcohol, food and tobacco selection and consumption. Independent, high-quality studies are urgently needed to inform policies on labelling regulations.

Airborne gamma-ray spectrometer and magnetometer survey: Victoria quadrangle (Washington). Final report

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

Not Available

1981-01-01

One uranium anomaly meets the minimum statistical requirements. Potassium (%K), equivalent Uranium (ppM eU), equivalent Thorium (ppM eT), eU/eT, eU/K, eT/K, and magnetic pseudo-contour maps are presented. Stacked Profiles showing geologic strip maps along each flight-line, together with sensor data, and ancillary data are presented. All maps and profiles were prepared on a scale of 1:250,000, but have been reduced to 1:500,000 for presentation. Anomaly number 1 is over an exposure of the Permian Shuksan metamorphic suite which is predominantly phyllite (Trps).

Treatment of Storm Fears Using Virtual Reality and Progressive Muscle Relaxation.

PubMed

Lima, Jessica; McCabe-Bennett, Hanna; Antony, Martin M

2018-03-01

The present study examined the efficacy of virtual reality (VR) exposure therapy for treating individuals with storm fears by comparing a one-session VR exposure treatment with a one-session progressive muscle relaxation (PMR) and psychoeducation session. It was predicted that there would be a reduction in storm-related fear post-treatment for individuals in both conditions, but that this reduction would be greater for those in the VR exposure condition. It was predicted that improvements would be maintained at 30-day follow-up only for those in the VR exposure condition. Thirty-six participants each received one of the two treatment conditions. Those in the PMR treatment group received approximately 30 minutes of PMR and approximately 15 minutes of psychoeducation regarding storms. Those in the VR treatment group received approximately 1 hour of VR exposure. Additionally, participants were asked to complete a pre-treatment and post-treatment 5-minute behavioural approach test to assess changes in storm fears. They were also asked to complete a measure assessing storm phobia. There was a significant interaction between treatment group and self-reported fear at post-treatment, such that fear decreased for both groups, although the reduction was stronger in the VR group. Results also showed that reductions in storm fear were maintained at 30-day follow-up for both groups. Although this study used a small non-clinical sample, these results offer preliminary support for the use of VR exposure therapy in the treatment of storm-related fear.