Science.gov

Sample records for shower exposure model

  1. An in-premise model for Legionella exposure during showering events

    EPA Science Inventory

    An exposure model was constructed to predict the critical Legionella densities in an engineered water system that might result in infection from inhalation of aerosols containing the pathogen while showering. The model predicted the Legionella densities in the shower air, water ...

  2. Monte Carlo modeling and meteor showers

    NASA Technical Reports Server (NTRS)

    Kulikova, N. V.

    1987-01-01

    Prediction of short lived increases in the cosmic dust influx, the concentration in lower thermosphere of atoms and ions of meteor origin and the determination of the frequency of micrometeor impacts on spacecraft are all of scientific and practical interest and all require adequate models of meteor showers at an early stage of their existence. A Monte Carlo model of meteor matter ejection from a parent body at any point of space was worked out by other researchers. This scheme is described. According to the scheme, the formation of ten well known meteor streams was simulated and the possibility of genetic affinity of each of them with the most probable parent comet was analyzed. Some of the results are presented.

  3. Modeling coherent cherenkov radio emissions from high energy electromagnetic showers.

    SciTech Connect

    Schoessow, P.

    1998-04-24

    A technique currently under study for the detection of ultrahigh energy cosmic ray neutrinos involves the measurement of radio emissions from the electromagnetic shower generated by the neutrino in a large volume of naturally occurring dielectric such as the Antarctic ice cap or salt domes. The formation of an electron excess in the shower leads to the emission of coherent Cherenkov radiation, an effect similar to the generation of wakefields in dielectric loaded structures. We have used the finite difference time domain (FDTD) wakefield code ARRAKIS to model coherent Cherenkov radiation fields from high energy showers; we present as an example calculations of expected signals in a proof of principle experiment proposed for the Fermilab Main Injector.

  4. Assessing human exposure and odor detection during showering with crude 4-(methylcyclohexyl)methanol (MCHM) contaminated drinking water.

    PubMed

    Sain, Amanda E; Dietrich, Andrea M; Smiley, Elizabeth; Gallagher, Daniel L

    2015-12-15

    In 2014, crude (4-methylcyclohexyl)methanol (MCHM) spilled, contaminating the drinking water of 300,000 West Virginians and requiring "do not use" orders to protect human health. When the spill occurred, known crude MCHM physicochemical properties were insufficient to predict human inhalation and ingestion exposures. Objectives are (1) determine Henry's Law Constants (HLCs) for 4-MCHM isomers at 7, 25, 40, and 80°C using gas chromatography; (2) predict air concentrations of 4-MCHM and methyl-4-methylcyclohexanecarboxylate (MMCHC) during showering using an established shower model; (3) estimate human ingestion and inhalation exposure to 4-MCHM and MMCHC; and (4) determine if predicted air 4-MCHM exceeded odor threshold concentrations. Dimensionless HLCs of crude cis- and trans-4-MCHM were measured to be 1.42×10(-4)±6% and 3.08×10(-4)±3% at 25°C, respectively, and increase exponentially with temperature as predicted by the van't Hoff equation. Shower air concentrations for cis- and trans-4-MCHM are predicted to be 0.089 and 0.390ppm-v respectively after 10min, exceeding the US EPA's 0.01ppm-v air screening level during initial spill conditions. Human exposure doses were predicted using measured drinking water and predicted shower air concentrations and found to greatly exceed available guidance levels in the days directly following the spill. Odors would be rapidly detected by 50% of individuals at aqueous concentrations below analytical gas chromatographic detection limits. MMCHC, a minor odorous component (0.935%) of crude MCHM, is also highly volatile and therefore is predicted to contribute to inhalation exposures and odors experienced by consumers. PMID:26311585

  5. Assessing human exposure and odor detection during showering with crude 4-(methylcyclohexyl)methanol (MCHM) contaminated drinking water.

    PubMed

    Sain, Amanda E; Dietrich, Andrea M; Smiley, Elizabeth; Gallagher, Daniel L

    2015-12-15

    In 2014, crude (4-methylcyclohexyl)methanol (MCHM) spilled, contaminating the drinking water of 300,000 West Virginians and requiring "do not use" orders to protect human health. When the spill occurred, known crude MCHM physicochemical properties were insufficient to predict human inhalation and ingestion exposures. Objectives are (1) determine Henry's Law Constants (HLCs) for 4-MCHM isomers at 7, 25, 40, and 80°C using gas chromatography; (2) predict air concentrations of 4-MCHM and methyl-4-methylcyclohexanecarboxylate (MMCHC) during showering using an established shower model; (3) estimate human ingestion and inhalation exposure to 4-MCHM and MMCHC; and (4) determine if predicted air 4-MCHM exceeded odor threshold concentrations. Dimensionless HLCs of crude cis- and trans-4-MCHM were measured to be 1.42×10(-4)±6% and 3.08×10(-4)±3% at 25°C, respectively, and increase exponentially with temperature as predicted by the van't Hoff equation. Shower air concentrations for cis- and trans-4-MCHM are predicted to be 0.089 and 0.390ppm-v respectively after 10min, exceeding the US EPA's 0.01ppm-v air screening level during initial spill conditions. Human exposure doses were predicted using measured drinking water and predicted shower air concentrations and found to greatly exceed available guidance levels in the days directly following the spill. Odors would be rapidly detected by 50% of individuals at aqueous concentrations below analytical gas chromatographic detection limits. MMCHC, a minor odorous component (0.935%) of crude MCHM, is also highly volatile and therefore is predicted to contribute to inhalation exposures and odors experienced by consumers.

  6. Household exposure models

    SciTech Connect

    McKone, T.E.

    1988-01-01

    Human exposure to volatile organic compounds (VOCs) in tap water is often assumed to be dominated by ingestion of drinking water. This paper addresses the relative importance of inhalation and dermal exposures in a typical household. A three-compartment model is used to simulate the 24-h concentration history of VOCs in the shower, bathroom, and remaining household volumes as a result of tap water use. Mass transfers from water to air are derived from measured data for radon and used to estimate mass-transfer properties for VOCs. The model is used to calculate a range of concentrations and human exposures in US dwellings. The estimated ratio of household- inhalation uptake to ingestion uptake is in the range of 1 to 6 for VOCs. We use a dermal absorption model to assess exposure across the skin boundary during baths and showers. The ratio of dermal exposure to ingestion exposure is in the range 0.6 to 1. 24 refs., 1 fig., 7 tabs.

  7. Cosmic-ray exposure history of two Frontier Mountain H-chondrite showers from spallation and neutron-capture products

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Nishiizumi, K.; Masarik, J.; Caffee, M. W.; Jull, A. J. T.; Klandrud, S. E.; Wieler, R.

    2001-02-01

    We measured the concentrations of 10Be, 26Al, 36Cl, 41Ca and 14C in the metal and/or stone fractions of 27 Antarctic chondrites from Frontier Mountain (FRO), including two large H-chondrite showers. To estimate the pre-atmospheric size of the two showers, we determined the contribution of neutron-capture produced 36Cl (half-life = 3.01 ´ 105 years) and 41Ca (1.04 ´ 105 years) in the stone fraction. The measured activities of neutron-capture 36Cl and 41Ca, as well as spallation produced 10Be and 26Al, were compared with Monte Carlo-based model calculations. The largest shower, FRO 90174, includes eight fragments with an average terrestrial age of (100 ~ 30) ´ 103 years; the neutron-capture saturation activities extend to 27 dpm/kg stone for 36Cl and 19 dpm/kg stone for 41Ca. The concentrations of spallation produced 10Be, 26Al and 36Cl constrain the radius (R) to 80-100 cm, while the neutron-capture 41Ca activities indicate that the samples originated from the outer 25 cm. With a pre-atmospheric radius of 80-100 cm, FRO 90174 is among the largest of the Antarctic stony meteorites. The large pre-atmospheric size supports our hypothesis that at least 50 of the ~150 classified H5/H6-chondrites from the Frontier Mountain stranding area belong to this single fall; this hypothesis does not entirely account for the high H/L ratio at Frontier Mountain. The smaller shower, FRO 90001, includes four fragments with an average terrestrial age of (40 ~ 10) ´ 103 years; they contain small contributions of neutron-capture 36Cl, but no excess of 41Ca. FRO 90001 experienced a complex exposure history with high shielding conditions in the first stage (150 < R < 300 cm) and much lower shielding in the second stage (R < 30 cm), the latter starting ~1.0 million years (Ma) ago. Based on the measured 10Be/21Ne and 26Al/21Ne ratios, the cosmic-ray exposure ages of the two showers are 7.2 ~ 0.5 Ma for FRO 90174 and 8 ~ 1 Ma for FRO 90001. These ages coincide with the well-established H

  8. Gamma-rays from dark showers with twin Higgs models

    NASA Astrophysics Data System (ADS)

    Freytsis, Marat; Knapen, Simon; Robinson, Dean J.; Tsai, Yuhsin

    2016-05-01

    We consider a twin WIMP scenario whose twin sector contains a full dark copy of the SM hadrons, where the lightest twin particles are twin pions. By analogy to the standard WIMP paradigm, the dark matter (DM) freezes out through twin electroweak interactions, and annihilates into a dark shower of light twin hadrons. These are either stable or decay predominantly to standard model (SM) photons. We show that this `hadrosymmetric' scenario can be consistent with all applicable astrophysical, cosmological and collider constraints. In order to decay the twin hadrons before the big-bang nucleosynthesis epoch, an additional portal between the SM and twin sector is required. In most cases we find this additional mediator is within reach of either the LHC or future intensity frontier experiments. Furthermore, we conduct simulations of the dark shower and consequent photon spectra. We find that fits of these spectra to the claimed galactic center gamma-ray excess seen by Fermi -LAT non-trivially coincide with regions of parameter space that both successfully generate the observed DM abundance and exhibit minimal fine-tuning.

  9. A Complex Exposure History of the Gold Basin L4-Chondrite Shower from Cosmogenic Radionuclides and Noble Gases

    NASA Technical Reports Server (NTRS)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.; Masarik, J.; Wieler, R.

    2001-01-01

    Cosmogenic radionuclides and noble gases in samples of the Gold Basin L-chondrite shower indicate a complex exposure history, with a first stage exposure on the parent body, followed by a second stage of approx. 19 Myr in a meteoroid 3-4 m in radius. Additional information is contained in the original extended abstract.

  10. Air shower simulation for WASAVIES: warning system for aviation exposure to solar energetic particles.

    PubMed

    Sato, T; Kataoka, R; Yasuda, H; Yashiro, S; Kuwabara, T; Shiota, D; Kubo, Y

    2014-10-01

    WASAVIES, a warning system for aviation exposure to solar energetic particles (SEPs), is under development by collaboration between several institutes in Japan and the USA. It is designed to deterministically forecast the SEP fluxes incident on the atmosphere within 6 h after flare onset using the latest space weather research. To immediately estimate the aircrew doses from the obtained SEP fluxes, the response functions of the particle fluxes generated by the incidence of monoenergetic protons into the atmosphere were developed by performing air shower simulations using the Particle and Heavy Ion Transport code system. The accuracy of the simulation was well verified by calculating the increase count rates of a neutron monitor during a ground-level enhancement, combining the response function with the SEP fluxes measured by the PAMELA spectrometer. The response function will be implemented in WASAVIES and used to protect aircrews from additional SEP exposure. PMID:24344351

  11. Air shower simulation for WASAVIES: warning system for aviation exposure to solar energetic particles.

    PubMed

    Sato, T; Kataoka, R; Yasuda, H; Yashiro, S; Kuwabara, T; Shiota, D; Kubo, Y

    2014-10-01

    WASAVIES, a warning system for aviation exposure to solar energetic particles (SEPs), is under development by collaboration between several institutes in Japan and the USA. It is designed to deterministically forecast the SEP fluxes incident on the atmosphere within 6 h after flare onset using the latest space weather research. To immediately estimate the aircrew doses from the obtained SEP fluxes, the response functions of the particle fluxes generated by the incidence of monoenergetic protons into the atmosphere were developed by performing air shower simulations using the Particle and Heavy Ion Transport code system. The accuracy of the simulation was well verified by calculating the increase count rates of a neutron monitor during a ground-level enhancement, combining the response function with the SEP fluxes measured by the PAMELA spectrometer. The response function will be implemented in WASAVIES and used to protect aircrews from additional SEP exposure.

  12. Investigation of human exposure to triclocarban after showering and preliminary evaluation of its biological effects.

    PubMed

    Schebb, Nils Helge; Inceoglu, Bora; Ahn, Ki Chang; Morisseau, Christophe; Gee, Shirley J; Hammock, Bruce D

    2011-04-01

    The antibacterial soap additive triclocarban (TCC) is widely used in personal care products. TCC has a high environmental persistence. We developed and validated a sensitive online solid-phase extraction-LC-MS/MS method to rapidly analyze TCC and its major metabolites in urine and other biological samples to assess human exposure. We measured human urine concentrations 0-72 h after showering with a commercial bar soap containing 0.6% TCC. The major route of renal elimination was excretion as N-glucuronides. The absorption was estimated at 0.6% of the 70±15 mg of TCC in the soap used. The TCC-N-glucuronide urine concentration varied widely among the subjects, and continuous daily use of the soap led to steady state levels of excretion. In order to assess potential biological effects arising from this exposure, we screened TCC for the inhibition of human enzymes in vitro. We demonstrate that TCC is a potent inhibitor of the enzyme soluble epoxide hydrolase (sEH), whereas TCC's major metabolites lack strong inhibitory activity. Topical administration of TCC at similar levels to rats in a preliminary in vivo study, however, failed to alter plasma biomarkers of sEH activity. Overall the analytical strategy described here revealed that use of TCC soap causes exposure levels that warrant further evaluation. PMID:21381656

  13. The Complex Exposure History of a Very Large L/LL5 Chondrite Shower: Queen Alexandra Range 90201

    NASA Technical Reports Server (NTRS)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.; Hillegonds, D. J.; Leya, I.; Wieler, R.; Mararik, J.

    2004-01-01

    Compared to iron meteorites, large stony meteorites (less than 100 kg) are relatively rare. Most large stony meteoroids fragment during atmospheric entry, producing large meteorite showers. Interestingly, many of these large chondrites, such as Bur Gheluai, Gold Basin, Jilin and Tsarev appear to have a complex exposure history with a first-stage exposure on the parent body. The question is whether complex exposure histories are simply more readily detected in large objects or large objects are more likely to experience a complex exposure. Investigation of these two hypotheses is the motivation for this work in which we report on the exposure history of QUE 90201, a large L/LL5 chondrite shower found near Queen Alexandra Range, Antarctica. Previous cosmogenic nuclide studies have led to the consensus that most of the approx. 2000 L5 and LL5 chondrites from the QUE area are derived from a single object with a pre-atmospheric radius of 1-2 m. The terrestrial age of the QUE 90201 shower was determined at 125 20 kyr. Here, we present a more complete set of cosmogenic radionuclide results in the metal and stone fractions of eleven L/LL5 chondrites from the QUE stranding area, as well as noble gases in seven of these samples. The main goal of this work is to unravel the cosmic-ray exposure history of the QUE 90201 meteoroid. In addition, we will discuss the pre-atmospheric size and exposure history of QUE 93013 (H5) and 93081 (H4) with similar shielding conditions as the QUE 90201 shower and a terrestrial age of 145 +/- 25 kyr.

  14. Opportunistic Pathogens Mycobacterium Avium Complex (MAC) and Legionella spp. Colonise Model Shower.

    PubMed

    Whiley, Harriet; Giglio, Steven; Bentham, Richard

    2015-07-24

    Legionella spp. and Mycobacterium avium complex (MAC) are opportunistic pathogens of public health concern. Hot water systems, including showers, have been identified as a potential source of infection. This paper describes the colonization of Legionella and MAC on the flexible tubing within a model potable shower system, utilizing thermostatic mixing and a flexible shower head. A MAC qPCR method of enumeration was also developed. MAC and Legionella spp. were detected within the biofilm at maximum concentrations of 7.0 × 104 and 2.0 × 103 copies/cm2 PVC tubing respectively. No significant changes were observed between sample of the flexible shower tubing that dried between uses and those that remained filled with water. This suggested the "unhooking" showerheads and allowing them to dry is not an effective method to reduce the risk of Legionella or MAC colonisation.

  15. Opportunistic Pathogens Mycobacterium Avium Complex (MAC) and Legionella spp. Colonise Model Shower.

    PubMed

    Whiley, Harriet; Giglio, Steven; Bentham, Richard

    2015-01-01

    Legionella spp. and Mycobacterium avium complex (MAC) are opportunistic pathogens of public health concern. Hot water systems, including showers, have been identified as a potential source of infection. This paper describes the colonization of Legionella and MAC on the flexible tubing within a model potable shower system, utilizing thermostatic mixing and a flexible shower head. A MAC qPCR method of enumeration was also developed. MAC and Legionella spp. were detected within the biofilm at maximum concentrations of 7.0 × 104 and 2.0 × 103 copies/cm2 PVC tubing respectively. No significant changes were observed between sample of the flexible shower tubing that dried between uses and those that remained filled with water. This suggested the "unhooking" showerheads and allowing them to dry is not an effective method to reduce the risk of Legionella or MAC colonisation. PMID:26213977

  16. Opportunistic Pathogens Mycobacterium Avium Complex (MAC) and Legionella spp. Colonise Model Shower

    PubMed Central

    Whiley, Harriet; Giglio, Steven; Bentham, Richard

    2015-01-01

    Legionella spp. and Mycobacterium avium complex (MAC) are opportunistic pathogens of public health concern. Hot water systems, including showers, have been identified as a potential source of infection. This paper describes the colonization of Legionella and MAC on the flexible tubing within a model potable shower system, utilizing thermostatic mixing and a flexible shower head. A MAC qPCR method of enumeration was also developed. MAC and Legionella spp. were detected within the biofilm at maximum concentrations of 7.0 × 104 and 2.0 × 103 copies/cm2 PVC tubing respectively. No significant changes were observed between sample of the flexible shower tubing that dried between uses and those that remained filled with water. This suggested the “unhooking” showerheads and allowing them to dry is not an effective method to reduce the risk of Legionella or MAC colonisation. PMID:26213977

  17. Electrons, muons and hadrons in extensive air showers and how do they depend on nuclear interaction model, part 1

    NASA Technical Reports Server (NTRS)

    Wrotniak, J. A.; Yodh, G. B.

    1985-01-01

    Monte Carlo simulations of extensive air showers were performed using a couple of different nuclear interaction models and obtaining a variety of shower characteristics. The discussion of these shows that the sensitivity of observables to the primary mass spectrum is significantly stronger than to the interaction model, the latter being quite weak.

  18. Ice surface roughness modeling for effect on radio signals from UHE particle showers

    NASA Astrophysics Data System (ADS)

    Stockham, Jessica

    2014-03-01

    For radio antenna detectors located in or above the Antarctic ice sheet, the reconstruction of both ultra-high energy (UHE) neutrino and cosmic ray air shower events requires understanding the transmission and reflection properties of the air-ice interface. To this end, surface and volume scattering from granular materials in the microwave frequency range are measured and stereoscopic images of the ice surface, obtained by the Antarctric Geophysics Along the Vostok Expedition (AGAVE), are used to determine the 3D surface structure. This data is implemented to determine an appropriate model for use in simulation and data analysis of the shower events. ANtarctic Impulsive Transient Antenna.

  19. Air Shower Simulations

    SciTech Connect

    Alania, Marco; Gomez, Adolfo V. Chamorro; Araya, Ignacio J.; Huerta, Humberto Martinez; Flores, Alejandra Parra; Knapp, Johannes

    2009-04-30

    Air shower simulations are a vital part of the design of air shower experiments and the analysis of their data. We describe the basic features of air showers and explain why numerical simulations are the appropriate approach to model the shower simulation. The CORSIKA program, the standard simulation program in this field, is introduced and its features, performance and limitations are discussed. The basic principles of hadronic interaction models and some gerneral simulation techniques are explained. Also a brief introduction to the installation and use of CORSIKA is given.

  20. Meteor Showers.

    ERIC Educational Resources Information Center

    Kronk, Gary W.

    1988-01-01

    Described are the history, formation, and observing techniques of meteors and comets. Provided are several pictures, diagrams, meteor organizations and publications, and meteor shower observation tables. (YP)

  1. INTEGRATED PROBABILISTIC AND DETERMINISTIC MODELING TECHNIQUES IN ESTIMATING EXPOSURE TO WATER-BORNE CONTAMINANTS: PART 2 PHARMACOKINETIC MODELING

    EPA Science Inventory

    The Total Exposure Model (TEM) uses deterministic and stochastic methods to estimate the exposure of a person performing daily activities of eating, drinking, showering, and bathing. There were 250 time histories generated, by subject with activities, for the three exposure ro...

  2. Modeling Film-Coolant Flow Characteristics at the Exit of Shower-Head Holes

    NASA Technical Reports Server (NTRS)

    Garg, Vijay K.; Gaugler, R. E. (Technical Monitor)

    2000-01-01

    The coolant flow characteristics at the hole exits of a film-cooled blade are derived from an earlier analysis where the hole pipes and coolant plenum were also discretized. The blade chosen is the VKI rotor with three staggered rows of shower-head holes. The present analysis applies these flow characteristics at the shower-head hole exits. A multi-block three-dimensional Navier-Stokes code with Wilcox's k-omega model is used to compute the heat transfer coefficient on the film-cooled turbine blade. A reasonably good comparison with the experimental data as well as with the more complete earlier analysis where the hole pipes and coolant plenum were also gridded is obtained. If the 1/7th power law is assumed for the coolant flow characteristics at the hole exits, considerable differences in the heat transfer coefficient on the blade surface, specially in the leading-edge region, are observed even though the span-averaged values of h (heat transfer coefficient based on T(sub o)-T(sub w)) match well with the experimental data. This calls for span-resolved experimental data near film-cooling holes on a blade for better validation of the code.

  3. Showering effectiveness for human hair decontamination of the nerve agent VX.

    PubMed

    Josse, Denis; Wartelle, Julien; Cruz, Catherine

    2015-05-01

    In this work, our goals were to establish whether hair decontamination by showering one hour post-exposure to the highly toxic organophosphate nerve agent VX was effective, whether it required the addition of a detergent to water and, if it could be improved by using the adsorbent Fuller's Earth (FE) or the Reactive Skin Decontamination Lotion (RSDL) 30 min prior to showering. Hair exposure to VX and decontamination was performed by using an in vitro model. Hair showering led to 72% reduction of contamination. Addition of detergent to water slightly increased the decontamination effectiveness. Hair treatment with FE or RSDL improved the decontamination rate. Combination of FE use and showering, which yielded a decontamination factor of 41, was demonstrated to be the most effective hair decontamination procedure. Hair wiping after showering was shown to contribute to hair decontamination. Altogether, our results highlighted the importance of considering hair decontamination as an important part of body surface decontamination protocols.

  4. Showering effectiveness for human hair decontamination of the nerve agent VX.

    PubMed

    Josse, Denis; Wartelle, Julien; Cruz, Catherine

    2015-05-01

    In this work, our goals were to establish whether hair decontamination by showering one hour post-exposure to the highly toxic organophosphate nerve agent VX was effective, whether it required the addition of a detergent to water and, if it could be improved by using the adsorbent Fuller's Earth (FE) or the Reactive Skin Decontamination Lotion (RSDL) 30 min prior to showering. Hair exposure to VX and decontamination was performed by using an in vitro model. Hair showering led to 72% reduction of contamination. Addition of detergent to water slightly increased the decontamination effectiveness. Hair treatment with FE or RSDL improved the decontamination rate. Combination of FE use and showering, which yielded a decontamination factor of 41, was demonstrated to be the most effective hair decontamination procedure. Hair wiping after showering was shown to contribute to hair decontamination. Altogether, our results highlighted the importance of considering hair decontamination as an important part of body surface decontamination protocols. PMID:25791764

  5. Minor meteor shower activity

    NASA Astrophysics Data System (ADS)

    Rendtel, J.

    2016-01-01

    Video meteor observations provide us with data to analyze structures in minor meteor showers or weak features in flux profiles. Samples obtained independently by other techniques allow to calibrate the data sets and to improve the confidence of results as demonstrated with a few results. Both, the confirmation of events predicted by model calculation and the input of observational data to improve the modelling results may help to better understand meteoroid stream evolution processes. Furthermore, calibrated data series can be used for studies of the long-term evolution of meteor shower activity.

  6. Use of computational models to reconstruct and predict trichloroethylene exposure.

    PubMed

    Maslia, M L; Aral, M M; Williams, R C; Williams-Fleetwood, S; Hayes, L C; Wilder, L C

    1996-01-01

    In this study, a type frequently encountered by ATSDR, groundwater and surface-water contamination have occurred near the Gratuity Road site in the town of Groton, Massachusetts. A petitioned public health assessment for the Gratuity Road site identified the primary contaminants as trichloro-ethylene (TCE), 1,1,1-trichloroethane (TCA), hexavalent chromium (Cr+6), chromium (Cr), and lead (Pb) (ATSDR 1992). The health assessment also indicated that off-site residential groundwater wells had been contaminated with TCE and TCA. Because direct measures of historical exposure to TCE are unavailable for the Gratuity Road site, computational models were used to reconstruct and predict exposure to TCE. These computational models included environmental transport and exposure models. For the environmental transport models, numerical methods were used to approximate the equations of groundwater flow and contaminant transport. Results of using environmental transport models provided us with the spatial and temporal database necessary to conduct an exposure analysis. This database indicated that groundwater concentrations of TCE typically exceeded EPA's MCL of 5 ppb for TCE. The study demonstrated that although a hazardous waste site can be remediated, nearby populations may experience significant exposure because of historical contamination, which will not be captured by remediation activities. The exposure analysis used simulated concentrations of TCE predicted by environmental transport models. These concentrations were used to compare exposure to TCE from inhalation in a one-compartment model shower with exposure from ingestion of domestic water contaminated by TCE. The exposure model indicated that exposure to TCE by the inhalation route during showering is nearly identical to exposure by ingestion of domestic water supplies contaminated with TCE. As a result, entry by inhalation route is as important as entry by ingestion route when conducting exposure analyses of

  7. A physiologically based pharmacokinetic assessment of tetrachlorethylene in groundwater for a bathing and showering determination

    SciTech Connect

    Rao, H.V.; Brown, D.R. )

    1993-02-01

    A two-step methodology is described to make a health-based determination for the bathing and showering use of the water from a private well contiminated with volatile organic chemicals. The chemical perchloroethylene (PERC) is utilized to illustrate the approach. First, a chemical-specific exposure model is used to predict the concentration of PERC in the shower air, shower water, and in the air above the bathtub. Second, a physiologically based pharmacokinetic (PBPK) model is used to predict the concentration of PERC delivered to the target tissue, the brain, since the focus is on neurological endpoints. The simulation exercise includes concurrent dermal and inhalation routes of exposure. A reference target tissue level (RTTL) in the brain is estimated using the PBPK model. A hazard index based on this benchmark guideline is used to make a regulatory determination for bathing and showering use of the contaminated water.

  8. A physiologically based pharmacokinetic assessment of tetrachloroethylene in groundwater for a bathing and showering determination.

    PubMed

    Rao, H V; Brown, D R

    1993-02-01

    A two-step methodology is described to make a health-based determination for the bathing and showering use of the water from a private well contaminated with volatile organic chemicals. The chemical perchloroethylene (PERC) is utilized to illustrate the approach. First, a chemical-specific exposure model is used to predict the concentration of PERC in the shower air, shower water, and in the air above the bathtub. Second, a physiologically based pharmacokinetic (PBPK) model is used to predict the concentration of PERC delivered to the target tissue, the brain, since the focus is on neurological endpoints. The simulation exercise includes concurrent dermal and inhalation routes of exposure. A reference target tissue level (RTTL) in the brain is estimated using the PBPK model. A hazard index based on this benchmark guideline is used to make a regulatory determination for bathing and showering use of the contaminated water.

  9. Measuring and Modeling Cosmic Ray Showers with an MBL System: An Undergraduate Project.

    ERIC Educational Resources Information Center

    Jackson, David P.; Welker, Matthew T.

    2001-01-01

    Describes a novel method for inducing and measuring cosmic ray showers using a low-cost, microcomputer-based laboratory system. Uses low counting-rate radiation monitors in the reproduction of Bruno Rossi's classic experiment. (Contains 16 references.) (Author/YDS)

  10. Gaining analytic control of parton showers

    SciTech Connect

    Tackmann, Frank; Bauer, Christian W.; Tackmann, Frank J.

    2007-05-14

    Parton showers are widely used to generate fully exclusive final states needed to compare theoretical models to experimental observations. While, in general, parton showers give a good description of the experimental data, the precise functional form of the probability distribution underlying the event generation is generally not known. The reason is that realistic parton showers are required to conserve four-momentum at each vertex. In this paper we investigate in detail how four-momentum conservation is enforced in a standard parton shower and why this destroysthe analytic control of the probability distribution. We show how to modify a parton shower algorithm such that it conserves four-momentum at each vertex, but for which the full analytic form of the probability distribution is known. We then comment how this analytic control can be used to match matrix element calculations with parton showers, and to estimate effects of power corrections and other uncertainties in parton showers.

  11. Electrons, muons and hadrons in extensive air showers and how do they depend on nuclear interaction model, part 2

    NASA Technical Reports Server (NTRS)

    Wrotniak, J. A.; Yodh, G. B.

    1985-01-01

    Some of the results of Monte Carlo simulations of extensive air showers for nuclear interactions models are presented. The most significant part of scaling violation effect is generated by the inclusion of rising cross-section. Among the models considered the lowest value for Eo/N(max) is obtained when rapidly rising cross-section and charge exchange are both included (model R-F01). The value is still 1.38 GeV/electron. Except at the highest energies, the sensitivity to atomic mass of the primary is greater than to specific assumptions about multiple production.

  12. Reweighting parton showers

    NASA Astrophysics Data System (ADS)

    Bellm, Johannes; Plätzer, Simon; Richardson, Peter; Siódmok, Andrzej; Webster, Stephen

    2016-08-01

    We report on the possibility of reweighting parton-shower Monte Carlo predictions for scale variations in the parton-shower algorithm. The method is based on a generalization of the Sudakov veto algorithm. We demonstrate the feasibility of this approach using example physical distributions. Implementations are available for both of the parton-shower modules in the Herwig 7 event generator.

  13. Strong interactions in air showers

    SciTech Connect

    Dietrich, Dennis D.

    2015-03-02

    We study the role new gauge interactions in extensions of the standard model play in air showers initiated by ultrahigh-energy cosmic rays. Hadron-hadron events remain dominated by quantum chromodynamics, while projectiles and/or targets from beyond the standard model permit us to see qualitative differences arising due to the new interactions.

  14. Muons in gamma showers

    NASA Technical Reports Server (NTRS)

    Stanev, T.; Vankov, C. P.; Halzen, F.

    1985-01-01

    Muon production in gamma-induced air showers, accounting for all major processes. For muon energies in the GeV region the photoproduction is by far the most important process, while the contribution of micron + micron pair creation is not negligible for TeV muons. The total rate of muons in gamma showers is, however, very low.

  15. Development and application of a human PBPK model for bromodichloromethane to investigate the impacts of multi-route exposure.

    PubMed

    Kenyon, Elaina M; Eklund, Christopher; Leavens, Teresa; Pegram, Rex A

    2016-09-01

    As a result of its presence in water as a volatile disinfection byproduct, bromodichloromethane (BDCM), which is mutagenic, poses a potential health risk from exposure via oral, dermal and inhalation routes. We developed a refined human physiologically based pharmacokinetic (PBPK) model for BDCM (including new chemical-specific human parameters) to evaluate the impact of BDCM exposure during showering and bathing on important measures of internal dose compared with oral exposure. The refined model adequately predicted data from the published literature for oral, dermal and bathing/showering exposures. A liter equivalency approach (L-eq) was used to estimate BDCM concentration in a liter of water consumed by the oral route that would be required to produce the same internal dose of BDCM resulting from a 20-min bath or a 10-min shower in water containing 10 µg l(-1) BDCM. The oral liter equivalent concentrations for the bathing scenario were 605, 803 and 5 µg l(-1) BDCM for maximum venous blood concentration (Cmax), the area under the curve (AUCv) and the amount metabolized in the liver per hour (MBDCM), respectively. For a 10-min showering exposure, the oral L-eq concentrations were 282, 312 and 2.1 µg l(-1) for Cmax, AUC and MBDCM, respectively. These results demonstrate large contributions of dermal and inhalation exposure routes to the internal dose of parent chemical reaching the systemic circulation, which could be transformed to mutagenic metabolites in extrahepatic target tissues. Thus, consideration of the contribution of multiple routes of exposure when evaluating risks from water-borne BDCM is needed, and this refined human model will facilitate improved assessment of internal doses from real-world exposures. Published 2015. This article has been contributed to by US Government employees and their work is in the public domain in the USA. PMID:26649444

  16. Radiation Effects Investigations Based on Atmospheric Radiation Model (ATMORAD) Considering GEANT4 Simulations of Extensive Air Showers and Solar Modulation Potential.

    PubMed

    Hubert, Guillaume; Cheminet, Adrien

    2015-07-01

    The natural radiative atmospheric environment is composed of secondary cosmic rays produced when primary cosmic rays hit the atmosphere. Understanding atmospheric radiations and their dynamics is essential for evaluating single event effects, so that radiation risks in aviation and the space environment (space weather) can be assessed. In this article, we present an atmospheric radiation model, named ATMORAD (Atmospheric Radiation), which is based on GEANT4 simulations of extensive air showers according to primary spectra that depend only on the solar modulation potential (force-field approximation). Based on neutron spectrometry, solar modulation potential can be deduced using neutron spectrometer measurements and ATMORAD. Some comparisons between our methodology and standard approaches or measurements are also discussed. This work demonstrates the potential for using simulations of extensive air showers and neutron spectroscopy to monitor solar activity.

  17. Inhalation exposure model for volatile chemicals from indoor uses of water

    NASA Astrophysics Data System (ADS)

    Wilkes, Charles R.; Small, Mitchell J.; Andelman, Julian B.; Giardino, Nicholas J.; Marshall, Joy

    An indoor air quality model, MAVRIQ, has been developed for use with a personal computer (PC) to simulate the air concentration of organic compounds due to volatilization of chemicals originating in the domestic water supply. MAVRIQ also simulates the inhalation exposure of individuals based on their location and water use behavior. An application of MAVRIQ, presented in this paper, demonstrates the effect of various water uses on the air concentrations in a test house, and on the inhalation exposure of the inhabitants. The occupants' activities, location and water-use patterns are shown to affect their inhalation exposure. In the case of a person who spends the majority of his or her time in a home (such as the primary child-care adult) with contaminated water supply, the daily inhalation exposure is likely to exceed the exposure from ingestion of the same water. A large part of the inhalation exposure occurs during showering and post-showering activities, but other water uses also contribute. In addition, it is shown that a simple remedial action, the installation of a bathroom exhaust fan, can result in significant reductions of the inhalation exposure.

  18. Cosmic ray air showers from sphalerons

    NASA Astrophysics Data System (ADS)

    Brooijmans, Gustaaf; Schichtel, Peter; Spannowsky, Michael

    2016-10-01

    The discovery of the Higgs boson marks a key ingredient to establish the electroweak structure of the Standard Model. Its non-abelian gauge structure gives rise to, yet unobserved, non-perturbative baryon and lepton number violating processes. We propose to use cosmic ray air showers, as measured, for example, at the Pierre Auger Observatory, to set a limit on the hadronic production cross section of sphalerons. We identify several observables to discriminate between sphaleron and QCD induced air showers.

  19. Therapeutic showering in labor.

    PubMed

    Stark, Mary Ann

    2013-08-01

    While showering is thought to be an effective coping strategy during labor, research on this comfort measure is lacking. The purpose of this study was to measure effectiveness of therapeutic showering on pain, coping, tension, anxiety, relaxation, and fatigue in labor. A quasi-experimental pretest-posttest single group design was conducted in a community hospital. Participants were women who had singleton, uncomplicated pregnancies and were in active labor at term (N = 24). After completing pretest measures, participants took a 30 min shower where they were encouraged to be seated but could choose positions of comfort. There were significant reductions in tension and anxiety and increased relaxation and coping. Showering may be a safe and effective comfort measure for healthy, laboring women who are experiencing tension or anxiety, or having difficulty relaxing or coping with labor. Further research is needed to test the maternal and neonatal outcomes of this nonpharmacologic comfort measure.

  20. Particle Size Distribution and Inhalation Dose of Shower Water Under Selected Operating Conditions

    PubMed Central

    Zhou, Yue; Benson, Janet M.; Irvin, Clinton; Irshad, Hammad; Cheng, Yung-Sung

    2010-01-01

    Showering produces respirable droplets that may serve to deposit pollutants such as trihalomethane decontamination products, heavy metals, inorganic salts, microbes, or cyanoacterial toxins within the respiratory tract. The extent and importance of this route of indoor exposure depend on the physical characteristics of the aerosol as well as the pollutant profile of the source water. The purpose of this study was to characterize shower-generated aerosols as a function of water flow rate, temperature, and bathroom location. Aerosols were generated within a shower stall containing a mannequin to simulate the presence of a human. Using hot water, the mass median diameter (MMD) of the droplets inside the shower and in the bathroom were 6.3–7.5 um and 5.2–6 µm, respectively. Size was independent of water flow rate. The particle concentration inside the shower ranged from 5 to 14 mg/m3. Aerosols generated using cold water were smaller (2.5–3.1 µm) and concentrations were lower (0.02–0.1 mg/m3) inside the shower stall. No aerosols were detected in the bathroom area when cold water was used. The International Commission on Radiological Protection model was used to estimate water deposition in the respiratory tract. For hot water, total deposition ranged from 11 to 14 mg, depending on water flow rate, with approximately 50% of this deposited in the extrathoracic region during assumed mouth breathing, and greater than 86% when nose breathing was assumed. Alveolar deposition was 6–10% and 0.9% assuming oral and nasal breathing, respectively. The consequences deposition of shower water droplets will depend on the nature and extent of any pollutants in the source water. PMID:17365038

  1. Particle size distribution and inhalation dose of shower water under selected operating conditions.

    PubMed

    Zhou, Yue; Benson, Janet M; Irvin, Clinton; Irshad, Hammad; Cheng, Yung-Sung

    2007-04-01

    Showering produces respirable droplets that may serve to deposit pollutants such as trihalomethane decontamination products, heavy metals, inorganic salts, microbes, or cyanoacterial toxins within the respiratory tract. The extent and importance of this route of indoor exposure depend on the physical characteristics of the aerosol as well as the pollutant profile of the source water. The purpose of this study was to characterize shower-generated aerosols as a function of water flow rate, temperature, and bathroom location. Aerosols were generated within a shower stall containing a mannequin to simulate the presence of a human. Using hot water, the mass median diameter (MMD) of the droplets inside the shower and in the bathroom were 6.3-7.5 um and 5.2-6 microm, respectively. Size was independent of water flow rate. The particle concentration inside the shower ranged from 5 to 14 mg/m3. Aerosols generated using cold water were smaller (2.5-3.1 microm) and concentrations were lower (0.02-0.1 mg/m3) inside the shower stall. No aerosols were detected in the bathroom area when cold water was used. The International Commission on Radiological Protection model was used to estimate water deposition in the respiratory tract. For hot water, total deposition ranged from 11 to 14 mg, depending on water flow rate, with approximately 50% of this deposited in the extrathoracic region during assumed mouth breathing, and greater than 86% when nose breathing was assumed. Alveolar deposition was 6-10% and 0.9% assuming oral and nasal breathing, respectively. The consequences deposition of shower water droplets will depend on the nature and extent of any pollutants in the source water.

  2. Measurement of parton shower observables with OPAL

    NASA Astrophysics Data System (ADS)

    Fischer, N.; Gieseke, S.; Kluth, S.; Plätzer, S.; Skands, P.

    2016-07-01

    A study of QCD coherence is presented based on a sample of about 397,000 e+e- hadronic annihilation events collected at √s = 91 GeV with the OPAL detector at LEP. The study is based on four recently proposed observables that are sensitive to coherence effects in the perturbative regime. The measurement of these observables is presented, along with a comparison with the predictions of different parton shower models. The models include both conventional parton shower models and dipole antenna models. Different ordering variables are used to investigate their influence on the predictions.

  3. The search for extended air showers at the Jicamarca Radio Observatory

    SciTech Connect

    Wahl, D.; Chau, J.; Galindo, F.; Huaman, A.; Solano, C. J.

    2009-04-30

    This paper presents the status of the project to detect extended air showers at the Jicamarca Radio Observatory. We report on detected anomalous signals and present a toy model to estimate at what altitudes we might expect to see air shower signals. According to this model, a significant number of high altitude horizontal air showers could be observed by radar techniques.

  4. 75 FR 859 - Exposure Modeling Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-06

    ... AGENCY Exposure Modeling Public Meeting AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of Cancellation and Rescheduling of meeting. SUMMARY: This notice announces that the Exposure Modeling Public... Facility telephone number is (703) 305-5805. II. Background The purpose of the Exposure Modeling...

  5. The Orbital Workshop Shower Compartment

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This photograph shows technicians performing a checkout of the Metabolic Analyzer (center background) and the Ergometer (foreground) in the Orbital Workshop (OWS). The shower compartment is at right. The Ergometer (Skylab Experiment M171) evaluated man's metabolic effectiveness and cost of work in space environment. Located in the experiment and work area of the OWS, the shower compartment was a cylindrical cloth enclosure that was folded flat when not in use. The bottom ring of the shower was fastened to the floor and contained foot restraints. The upper ring contained the shower head and hose. To use the shower, the astronaut filled a pressurized portable bottle with heated water and attached the bottle to the ceiling. A flexible hose cornected the water bottle to a handheld shower head. The astronaut pulled the cylindrical shower wall up into position and bathed, using liquid soap. Both soap and water were carefully rationed, having been premeasured for economical use.

  6. The Orbital Workshop Shower Compartment

    NASA Technical Reports Server (NTRS)

    1972-01-01

    In this photograph, the Orbital Workshop shower compartment was unfolded by technicians for inspection. The shower compartment was a cylindrical cloth enclosure that was folded flat when not in use. The bottom ring of the shower was fastened to the floor and contained foot restraints. The upper ring contained the shower head and hose. To use the shower, the astronaut filled a pressurized portable bottle with heated water and attached the bottle to the ceiling. A flexible hose cornected the water bottle to a handheld shower head. The astronaut pulled the cylindrical shower wall up into position and bathed, using liquid soap. Both soap and water were carefully rationed, having been premeasured for economical use.

  7. Portable shower apparatus

    NASA Technical Reports Server (NTRS)

    Grenier, Francis E. (Inventor)

    1993-01-01

    A multipurpose, collapsible, shower apparatus for use almost anywhere but especially adapted for use in places somewhat remote from civilization such as recreational vehicles, campers, the outdoors, space vehicles and the like where there may be a limited amount of water or other liquid. The collapsible shower apparatus includes a curtain assembly having an inner wall, an outer wall and a porous element for separating the inner and outer walls; a series of spaced hollow hoops connected by one or more sets of hollow tubes (manifolds); one or more nozzles connected to and in communication with at least one of the hollow hoops; a source of fluid under pressure in communication with at least one of the hollow hoops; and a suction pump for withdrawing fluid from the interior of the curtain assembly.

  8. THE RETURN OF THE ANDROMEDIDS METEOR SHOWER

    SciTech Connect

    Wiegert, Paul A.; Brown, Peter G.; Weryk, Robert J.; Wong, Daniel K.

    2013-03-15

    back five Lyapunov times (which is only 25 yr for the highly perturbed parent). As a result, the stream evolution is somewhat uncertain and some discrepancy with the observations is to be expected: the radiant is 8 Degree-Sign off, the inclination 3 Degree-Sign higher, and the peak of the shower occurs a day earlier than predicted. Predictions are made regarding other appearances of the shower in the years 2000-2047 based on our numerical model. We note that the details of the 2011 return can, in principle, be used to better constrain the orbit of 3D/Biela prior to the comets first recorded return in 1772 and we address this issue briefly as well.

  9. COMET SHOWERS ARE NOT INDUCED BY INTERSTELLAR CLOUDS

    SciTech Connect

    Morris, D.E.

    1985-11-01

    Encounters with interstellar clouds (IC) have been proposed by Rampino and Stothers as a cause of quasi-periodic intense comet showers leading to earth impacts, in order to explain the periodicity in marine mass extinctions found by Raup and Sepkoski. The model was described further, criticized and defended. The debate has centered on the question of whether the scale height of the clouds is small enough (in comparison to the amplitude of the oscillation of the solar system about the plane of the Galaxy) to produce a modulation in the rate of encounters. We wish to point out another serious, we believe fatal, defect in this model - the tidal fields of ICs are not strong enough to produce intense comet showers leading to earth impacts by bringing comets of the postulated inner Oort cloud into earth crossing orbits, except possibly during very rare encounters with very dense clouds. We will show that encounters with abundant clouds of low density cannot produce comet showers; cloud density N > 10{sup 3} atoms cm{sup -3} is needed to produce an intense comet shower leading to earth impacts. Furthermore, the tidal field of a dense cloud during a distant encounter is too weak to produce such showers. As a consequence, comet showers induced by ICs will be far less frequent than showers caused by passing stars. This conclusion is independent of assumptions about the radial distribution of comets in the inner Oort cloud.

  10. E.M. and Hadronic Shower Simulation with FLUKA

    SciTech Connect

    Battistoni, G.; Fasso, A.; Ferrari, A.; Ranft, J.; Rubbia, A.; Sala, P.R.; /INFN, Milan /SLAC /CERN /Siegen U. /Zurich, ETH

    2005-10-03

    A description of the main features of e.m. and hadronic shower simulation models used in the FLUKA code is summarized and some recent applications are discussed. The general status of the FLUKA project is also reported.

  11. A Fast Hybrid Approach to Air Shower Simulations and Applications

    NASA Astrophysics Data System (ADS)

    Drescher, H.-J.; Farrar, Glennys; Bleicher, Marcus; Reiter, Manuel; Soff, Sven; Stoecker, Horst

    2003-07-01

    The SENECA model, a new hybrid approach to air shower simulations, is presented. It combines the use of efficient cascade equations in the energy range where a shower can be treated as one-dimensional, with a traditional Monte Carlo method which traces individual particles. This allows one to repro duce natural fluctuations of individual showers as well as the lateral spread of low energy particles. The model is quite efficient in computation time. As an application of the new approach, the influence of the low energy hadronic models on shower properties for AUGER energies is studied. We conclude that these models have a significant impact on the tails of lateral distribution functions, and deserve therefore more attention.

  12. 75 FR 22401 - Exposure Modeling Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-28

    ... AGENCY Exposure Modeling Public Meeting AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: An Exposure Modeling Public Meeting (EMPM) will be held for one day on July 27, 2010. This notice... Yard (South Building), 1st Floor South Conference Room, 2777 S. Crystal Drive, Arlington, VA 22202....

  13. 78 FR 60870 - Exposure Modeling Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-02

    ... AGENCY Exposure Modeling Public Meeting AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of public meeting. SUMMARY: An Exposure Modeling Public Meeting (EMPM) will be held for 1 day on October 8... Potomac Yard (North Building), Fourth Floor Conference Center (N-4830), 2777 S. Crystal Dr., Arlington,...

  14. 76 FR 365 - Exposure Modeling Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-04

    ... AGENCY Exposure Modeling Public Meeting AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: An Exposure Modeling Public Meeting (EMPM) will be held for one day on January 11, 2011. This... disability, please contact the person listed under FOR FURTHER INFORMATION CONTACT, preferably prior to...

  15. The muon content of gamma-ray showers

    NASA Technical Reports Server (NTRS)

    Edwards, P. G.; Protheroe, R. J.

    1985-01-01

    The result of a calculation of the expected number of muons in gamma ray initiated and cosmic ray initiated air showers using a realistic model of hadronic collisions in an effort to understand the available experimental results and to assess the feasibility of using the muon content of showers as a veto to reject cosmic ray initiated showers in ultra-high energy gamma ray astronomy are reported. The possibility of observing very-high energy gamma-ray sources by detecting narrow angle anisotropies in the high energy muon background radiation are considered.

  16. Modeling Particle Exposure in US Trucking Terminals

    PubMed Central

    Davis, ME; Smith, TJ; Laden, F; Hart, JE; Ryan, LM; Garshick, E

    2007-01-01

    Multi-tiered sampling approaches are common in environmental and occupational exposure assessment, where exposures for a given individual are often modeled based on simultaneous measurements taken at multiple indoor and outdoor sites. The monitoring data from such studies is hierarchical by design, imposing a complex covariance structure that must be accounted for in order to obtain unbiased estimates of exposure. Statistical methods such as structural equation modeling (SEM) represent a useful alternative to simple linear regression in these cases, providing simultaneous and unbiased predictions of each level of exposure based on a set of covariates specific to the exposure setting. We test the SEM approach using data from a large exposure assessment of diesel and combustion particles in the US trucking industry. The exposure assessment includes data from 36 different trucking terminals across the United States sampled between 2001 and 2005, measuring PM2.5 and its elemental carbon (EC), organic carbon (OC) components, by personal monitoring, and sampling at two indoor work locations and an outdoor “background” location. Using the SEM method, we predict: 1) personal exposures as a function of work related exposure and smoking status; 2) work related exposure as a function of terminal characteristics, indoor ventilation, job location, and background exposure conditions; and 3) background exposure conditions as a function of weather, nearby source pollution, and other regional differences across terminal sites. The primary advantage of SEMs in this setting is the ability to simultaneously predict exposures at each of the sampling locations, while accounting for the complex covariance structure among the measurements and descriptive variables. The statistically significant results and high R2 values observed from the trucking industry application supports the broader use of this approach in exposure assessment modeling. PMID:16856739

  17. Various meteor scenes III: Recurrent showers and some minor showers

    NASA Astrophysics Data System (ADS)

    Koseki, Masahiro

    2015-02-01

    Meteor activities vary widely from year to year. We study here the June Bootids (JBO), τ-Herculids (TAH), and Andromedids (AND) which are basic examples for the recurrent nature of meteor showers. Half a century has passed since well-known photographic or radar meteor showers were detected. It is necessary to note that some `established' IAU showers are historical ones and we cannot always see them. We find the historical trace of AND by video and four distinct activities in the area of JBC (=JBO+TAH). Meteor showers look different by different observational techniques. Many minor showers in the IAU list have been detected only by observations stored for many days and many years; visual observations in a single night cannot perceive them naturally. We studied the φ-Piscids (PPS), χ-Taurids (CTA), γ-Ursae Minorids (GUM), η-Pegasids (ETP), and α-Sextantids (ASX) as examples and found they have not been recognized by visual observers at all. It is noteworthy that some of them have possible identifications in the IAU list and in preceding observations or reports. The difference in search methods makes the situations much more complicated. The five minor showers we studied here do not have confirmations by all observational techniques. Geobased search (radiant point, time of the observation, and possibly geocentric velocity) may overlook showers which are dispersed in radiant position. A search using the D-criterion is dependent on the presumption of a spherical distribution in the orbital space and may not represent the real distribution, or may overestimate the accuracy of the observations and lead to subdividing the showers into several parts. We must use these search methods properly.

  18. Inhalation exposure to VOCs from household use of contaminated domestic water

    SciTech Connect

    Aggarwal, P.K.

    1994-04-01

    Inhalation and dermal exposure by showering has been identified as a significant route of exposure to volatile organic compounds (VOCs). Elimination of the ingestion route of exposure by providing bottled water alone, therefore, may not be protective of human health; and the removal of VOCs from alternative water supplies may be required. This change may tremendously increase the cost of providing alternative water supplies to communities where private wells are the p source of water. Previously published laboratory and field studies for quantifying inhalation exposure during showering have been conducted in nearly closed chambers with air exchange in the shower area. Theoretical modeling studies for indoor air exposure have also assumed that air exchange rates during showering are negligible; however, air exchange rates on the order of 5-10 air changes per hour can easily be achieved by using commercially available ventilation fans. Calculated VOC concentrations in air at higher air exchange rates are lower, and the estimated inhalation dose in a ventilated shower is less than half of or lower than (depending on the volatilization rate) that in a relatively closed shower chamber. Calculated excess health risks from inhalation exposure to carbon tetrachloride in ventilated showers are on the order of 1 x 10{sup {minus}5} to 1 x 10{sup {minus}6} at water concentrations of carbon tetrachloride of about 30-200 {mu}g/L. Consequently, if ventilation of the shower area is considered as a mitigating factor, bottled water could provide a safe alternative supply where existing supplies are contaminated at levels much higher than the maximum contaminant level. The suggestion is made that a critical reevaluation of the data and models used to derive the water-quality standards for inhalation exposures should be considered.

  19. Electromagnetic Showers at High Energy

    ERIC Educational Resources Information Center

    Loos, J. S.; Dawson, S. L.

    1978-01-01

    Some of the properties of electromagnetic showers observed in an experimental study are illustrated. Experimental data and results from quantum electrodynamics are discussed. Data and theory are compared using computer simulation. (BB)

  20. Extensive air showers (HE-4)

    NASA Technical Reports Server (NTRS)

    Clay, R. W.

    1986-01-01

    Ultra high energy (UHE) gamma ray astronomy is an exciting area which has added a new sense of purpose to ground based array work. There is much to be done before UHE gamma ray showers can be understood properly and it is important to remain conservative with claims while the properties of such showers are still not clear. The muon content is only one of the properties that needs to be clarified. It remains to be seen how well progress occurs on the second order problem of detailed interaction parameters once the gross features are clarified. The shower disk thickness has become an area of intense study with interest in Linsley's technique for measuremnts of giant showers and in the study of structure near the core for improving fast timing and studying delayed subshowers. Perhaps the most significant area of promise for the future is individual shower develpments with Cerenkov and, particularly, air fluorescence techniques. The importance and potential of having relatively complete information on a complete set of individual showers can hardly be overestimated. A complete understanding of the observation process is needed to determine whether or not the recorded data set is complete at a given energy, apparent core distance, and zenith angle.

  1. Therapeutic Process During Exposure: Habituation Model

    PubMed Central

    Benito, Kristen G.; Walther, Michael

    2015-01-01

    The current paper outlines the habituation model of exposure process, which is a behavioral model emphasizing use of individually tailored functional analysis during exposures. This is a model of therapeutic process rather than one meant to explain the mechanism of change underlying exposure-based treatments. Habitation, or a natural decrease in anxiety level in the absence of anxiety-reducing behavior, might be best understood as an intermediate treatment outcome that informs therapeutic process, rather than as a mechanism of change. The habituation model purports that three conditions are necessary for optimal benefit from exposures: 1) fear activation, 2) minimization of anxiety-reducing behaviors, and 3) habituation. We describe prescribed therapist and client behaviors as those that increase or maintain anxiety level during an exposure (and therefore, facilitate habituation), and proscribed therapist and client behaviors as those that decrease anxiety during an exposure (and therefore, impede habituation). We illustrate model-consistent behaviors in the case of Monica, as well as outline the existing research support and call for additional research to further test the tenets of the habituation model as described in this paper. PMID:26258012

  2. The Mbale meteorite shower

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Betlem, Hans; Betlem, Jan; Barifaijo, Erasmus; Schluter, Thomas; Hampton, Craig; Laubenstien, Matthias; Kunz, Joachim; Heusser, Gerd

    1994-01-01

    On 1992 August 14 at 12:40 UTC, an ordinary chondrite of type L5/6 entered the atmosphere over Mbale, Uganda, broke up, and caused a strewn field of size 3 x 7 km. Shortly after the fall, an expedition gathered eye witness accounts and located the position of 48 impacts of masses between 0.19 and 27.4 kg. Short-lived radionuclide data were measured for two specimens, one of which was only 12 days after the fall. Subsequent recoveries of fragements has resulted in a total of 863 mass estimates by 1993 October. The surfaces of all fragments contain fusion crust. The meteorite shower caused some minor inconveniences. Most remarkably, a young boy was hit on the head by a small specimen. The data interpreted as to indicate that the meteorite had an initial mass between 400-1000 kg (most likely approximately 1000 kg) and approached Mbale from AZ = 185 +/- 15, H = 55 +/- 15, and V(sub infinity) = 13.5 +/- 1.5/s. Orbital elements are given. Fragmentation of the initial mass started probably above 25 km altitude, but the final catastrophic breakup occurred at an altitude of 10-14 km. An estimated 190 +/- 40 kg reached the Earth's surface minutes after the final breakup of which 150 kg of material has been recovered.

  3. RECENT ENHANCEMENTS TO THE DIETARY EXPOSURE POTENTIAL MODEL

    EPA Science Inventory

    Presentation describes recent enhancements & new applications of the Dietary Exposure Potential Model (DEPM), a model developed to assist in design & interpretation of dietary exposure measurements. Model is an interactive system that provides dietary exposure estimates using dat...

  4. Modeling and Predicting Pesticide Exposures

    EPA Science Inventory

    Models provide a means for representing a real system in an understandable way. They take many forms, beginning with conceptual models that explain the way a system works, such as delineation of all the factors and parameters of how a pesticide particle moves in the air after a s...

  5. Precise determination of muon and electromagnetic shower contents from a shower universality property

    SciTech Connect

    Yushkov, A.; Ambrosio, M.; Aramo, C.; D'Urso, D.; Valore, L.; Guarino, F.

    2010-06-15

    We consider two new aspects of extensive air shower development universality allowing to make an accurate estimation of muon and electromagnetic (EM) shower contents in two independent ways. In the first case, to get the muon (or EM) signal in water Cherenkov tanks or in scintillator detectors, it is enough to know the vertical depth of the shower maximum X{sub max}{sup v} and the total signal in the ground detector. In the second case, the EM signal can be calculated from the primary particle energy and the zenith angle. In both cases, the parametrizations of muon and EM signals are almost independent on the primary particle nature, energy and zenith angle. Implications of the considered properties for mass composition and hadronic interaction studies are briefly discussed. The present study is performed on 28 000 proton, oxygen, and iron showers, generated with CORSIKA 6.735 for the E{sup -1} spectrum in the energy range lg (E/eV)=18.5-20 and uniformly distributed in cos{sup 2{theta}} in the zenith angle interval {theta}=0 deg. - 65 deg. for QGSJET II/Fluka interaction models.

  6. DEVELOPING MEANINGFUL COHORTS FOR HUMAN EXPOSURE MODELS

    EPA Science Inventory

    This paper summarizes numerous statistical analyses focused on the U.S. Environmental Protection Agency's Consolidated Human Activity Database (CHAD), used by many exposure modelers as the basis for data on what people do and where they spend their time. In doing so, modelers ...

  7. Comet C/1917 F1 (Mellish) meteor shower complex

    NASA Astrophysics Data System (ADS)

    Hajdukova, M.; Neslusan, L.

    2014-07-01

    In this study, we mapped the whole meteor complex of the long-period comet C/1917 F1 (Mellish), using a procedure of proven reliability when investigating the 96P/Machholz and 2003 EH1 streams (Neslusan et al., 2013a; 2013b). For five perihelion passages of the comet C/1917 F1 in the past, we modeled associated theoretical streams, each consisting of 10000 test particles, and followed their dynamical evolution until the present. Subsequently, we analyzed the orbital characteristics of the parts of a stream that approach the Earth's orbit. These particles were used to predict the corresponding meteor showers. The predicted showers were searched for in the databases of actually observed meteors. According to our modeling, the meteoroid stream of the comet Mellish can be split into 4 filaments (F1 to F4), with 4 distinct radiant areas. The most numerous shower that originates in the comet nucleus of C/1917 F1 corresponds to theoretical filament F3. The meteoroids of this filament approach to the Earth's orbit relatively soon after their ejection from the nucleus. We identified this filament as the December Monocerotids (No. 19 in the IAU MDC list of the established showers). In the phase space of orbital elements, the shower occurs in the vicinity of another established shower, 250 November Orionids. However, shower No. 250 is obviously not related to C/1917 F1 since no single theoretical particle, in all five models, is in an orbit similar to the mean orbit of this shower. Filament F1 might be identified to 348 April rho-Cygnids, the meteoroid stream that was recently discovered by the Canadian Meteor Orbit Radar (Brown et al., 2010). In our models, this filament is numerous and, hence, the shower is well predicted. The particles of filament F1 and, therefore, the real April rho-Cygnids originating in C/1917 F1 can approach the Earth's orbit and collide with our planet not earlier than about 20 millennia after their release from the parent-comet nucleus. Despite this

  8. Conceptual model for assessment of dermal exposure

    PubMed Central

    Schneider, T.; Vermeulen, R.; Brouwer, D. H.; Cherrie, J. W.; Kromhout, H.; Fogh, C. L.

    1999-01-01

    Dermal exposure, primarily to pesticides, has been measured for almost half a century. Compared with exposure by inhalation, limited progress has been made towards standardisation of methods of measurement and development of biologically relevant exposure measures. It is suggested that the absence of a consistent terminology and a theoretical model has been an important cause of this lack of progress. Therefore, a consistent terminology based on a multicompartment model for assessment of dermal exposure is proposed that describes the transport of contaminant mass from the source of the hazardous substance to the surface of the skin. Six compartments and two barriers together with eight mass transport processes are described. With the model structure, examples are given of what some existing methods actually measure and where there are limited, or no, methods for measuring the relevant mass in a compartment or transport of mass. The importance of measuring the concentration of contaminant and not mass per area in the skin contaminant layer is stressed, as it is the concentration difference between the skin contamination layer and the perfused tissue that drives uptake. Methods for measuring uptake are currently not available. Measurement of mass, concentration, and the transport processes must be based on a theoretical model. Standardisation of methods of measurement of dermal exposure is strongly recommended.   PMID:10658563

  9. 1997 Leonid Shower From Space

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Nugent, David; Murthy, Jayant; Tedesco, Ed; DeVincenzi, Donal L. (Technical Monitor)

    2000-01-01

    In November 1997, the Midcourse Space Experiment satellite (MSX) was deployed to observe the Leonid shower from space. The shower lived up to expectations, with abundant bright fireballs. Twenty-nine meteors were detected by a wide-angle, visible wavelength, camera near the limb of the Earth in a 48-minute interval, and three meteors by the narrow field camera. This amounts to a meteoroid influx of 5.5 +/- 0.6 10(exp -5)/sq km hr for masses greater than 0.3 gram. The limiting magnitude for limb observations of Leonid meteors was measured at M(sub v) = -1.5 magn The Leonid shower magnitude population index was 1.6 +/- 0.2 down to M(sub v) = -7 magn., with no sign of an upper mass cut-off.

  10. Modeling Human Exposure to Indoor Contaminants: External Source to Body Tissues.

    PubMed

    Webster, Eva M; Qian, Hua; Mackay, Donald; Christensen, Rebecca D; Tietjen, Britta; Zaleski, Rosemary

    2016-08-16

    Information on human indoor exposure is necessary to assess the potential risk to individuals from many chemicals of interest. Dynamic indoor and human physicologically based pharmacokinetic (PBPK) models of the distribution of nonionizing, organic chemical concentrations in indoor environments resulting in delivered tissue doses are developed, described and tested. The Indoor model successfully reproduced independently measured, reported time-dependent air concentrations of chloroform released during showering and of 2-butyoxyethanol following use of a volatile surface cleaner. The Indoor model predictions were also comparable to those from a higher tier consumer model (ConsExpo 4.1) for the surface cleaner scenario. The PBPK model successful reproduced observed chloroform exhaled air concentrations resulting from an inhalation exposure. Fugacity based modeling provided a seamless description of the partitioning, fluxes, accumulation and release of the chemical in indoor media and tissues of the exposed subject. This has the potential to assist in health risk assessments, provided that appropriate physical/chemical property, usage characteristics, and toxicological information are available. PMID:27434742

  11. The 2014 May Camelopardalid Meteor Shower

    NASA Technical Reports Server (NTRS)

    Cooke, Bill; Moser, Danielle

    2014-01-01

    On May 24, 2014 Earth will encounter multiple streams of debris laid down by Comet 209P LINEAR. This will likely produce a new meteor shower, never before seen. Rates predicted to be from 100 to 1000 meteors per hour between 2 and 4 AM EDT, so we are dealing with a meteor outburst, potentially a storm. Peak rate of 200 per hour best current estimate. Difficult to calibrate models due to lack of past observations. Models indicate mm size particles in stream, so potential risk to Earth orbiting spacecraft.

  12. The maximum depth of shower with E sub 0 larger than 10(17) eV on average characteristics of EAS different components

    NASA Technical Reports Server (NTRS)

    Glushkov, A. V.; Efimov, N. N.; Makarov, I. T.; Pravdin, M. I.; Dedenko, L. G.

    1985-01-01

    The extensive air shower (EAS) development model independent method of the determination of a maximum depth of shower (X sub m) is considered. X sub m values obtained on various EAS parameters are in a good agreement.

  13. 46 CFR 154.1410 - Decontamination shower.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Decontamination shower. 154.1410 Section 154.1410... Equipment § 154.1410 Decontamination shower. When Table 4 references this section, a vessel carrying the listed cargo must have a decontamination shower and an eye wash that: (a) Are on the weatherdeck; and...

  14. 46 CFR 154.1410 - Decontamination shower.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Decontamination shower. 154.1410 Section 154.1410... Equipment § 154.1410 Decontamination shower. When Table 4 references this section, a vessel carrying the listed cargo must have a decontamination shower and an eye wash that: (a) Are on the weatherdeck; and...

  15. 46 CFR 154.1410 - Decontamination shower.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Decontamination shower. 154.1410 Section 154.1410... Equipment § 154.1410 Decontamination shower. When Table 4 references this section, a vessel carrying the listed cargo must have a decontamination shower and an eye wash that: (a) Are on the weatherdeck; and...

  16. 46 CFR 154.1410 - Decontamination shower.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Decontamination shower. 154.1410 Section 154.1410... Equipment § 154.1410 Decontamination shower. When Table 4 references this section, a vessel carrying the listed cargo must have a decontamination shower and an eye wash that: (a) Are on the weatherdeck; and...

  17. 46 CFR 154.1410 - Decontamination shower.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Decontamination shower. 154.1410 Section 154.1410... Equipment § 154.1410 Decontamination shower. When Table 4 references this section, a vessel carrying the listed cargo must have a decontamination shower and an eye wash that: (a) Are on the weatherdeck; and...

  18. Protocol to predict the dry skin benefit from the unique in-shower body lotion product form.

    PubMed

    Ertel, Keith; Rodriguez, Victorruben; Bacon, Robert; Farris, Richard; Hartwig, Paula

    2008-01-01

    A controlled exposure method was developed to predict dry skin improvement from a new in-shower body lotion product form. An in-shower body lotion is used in the shower after cleansing, and methods for cleansers and leave-on lotions are not applicable. Protocol parameters were chosen on the basis of consumer habits and practices studies and randomized clinical testing. The resulting protocol is consumer-relevant, and reliably and reproducibly predicts dry skin improvement from the in-shower body lotion product form.

  19. Modeling residential exposure to secondhand tobacco smoke

    NASA Astrophysics Data System (ADS)

    Klepeis, Neil E.; Nazaroff, William W.

    We apply a simulation model to explore the effect of a house's multicompartment character on a nonsmoker's inhalation exposure to secondhand tobacco smoke (SHS). The model tracks the minute-by-minute movement of people and pollutants among multiple zones of a residence and generates SHS pollutant profiles for each room in response to room-specific smoking patterns. In applying the model, we consider SHS emissions of airborne particles, nicotine, and carbon monoxide in two hypothetical houses, one with a typical four-room layout and one dominated by a single large space. We use scripted patterns of room-to-room occupant movement and a cohort of 5000 activity patterns sampled from a US nationwide survey. The results for scripted and cohort simulation trials indicate that the multicompartment nature of homes, manifested as inter-room differences in pollutant levels and the movement of people among zones, can cause substantial variation in nonsmoker SHS exposure.

  20. SUMMARY OF THE 2006 HADRONIC SHOWER SIMULATION WORKSHOP

    SciTech Connect

    WATERS, LAURIE S.

    2007-01-19

    The 2006 Hadronic Shower Simulation Workshop, held September 6-8, 2006 at Fermi National Laboratory brought together an international assembly of experts in the field of hadronic shower development. The overall goal was to present the current understanding of the physics of hadronic showers, and to study examples of how this is measured in particle-physics calorimetry. The modeling of such events is critical, and the major Monte Carlo codes, FLUKA, GEANT, MARS, MCNPX, and PHTS were represented at the workshop. A wide range of physics, much of which is used by the simulation codes was also discussed, ranging from the hadronic CEM, LAQGSM, and DTUJET models, down to low energy neutronics capabilities. Special purpose codes and methodologies used for specific applications such as muon and neutrino physics were also shown. The results of a code benchmarking exercises were presented and extensively discussed. This paper summarizes the key topics presented in the workshop.

  1. Analysis of extensive air showers with the hybrid code SENECA

    NASA Astrophysics Data System (ADS)

    Ortiz, Jeferson A.; de Souza, Vitor; Medina-Tanco, Gustavo

    The ultrahigh energy tail of the cosmic ray spectrum has been explored with unprecedented detail. For this reason, new experiments are exerting a severe pressure on extensive air shower modeling. Detailed fast codes are in need in order to extract and understand the richness of information now available. In this sense we explore the potential of SENECA, an efficient hybrid tridimensional simulation code, as a valid practical alternative to full Monte Carlo simulations of extensive air showers generated by ultrahigh energy cosmic rays. We discuss the influence of this approach on the main longitudinal characteristics of proton, iron nucleus and gamma induced air showers for different hadronic interaction models. We also show the comparisons of our predictions with those of CORSIKA code.

  2. Results on reuse of reclaimed shower water

    NASA Technical Reports Server (NTRS)

    Verostko, Charles E.; Garcia, Rafael; Pierson, Duane L.; Reysa, Richard P.; Irbe, Robert

    1986-01-01

    The Waste Water Recovery System that has been used in conjunction with a microgravity whole body shower to test a closed loop shower water reclamation system applicable to the NASA Space Station employs a Thermoelectric Integrated Hollow Fiber Membrane Evaporation Subsystem. Attention is given to the suitability of a Space Shuttle soap for such crew showers, the effects of shower water on the entire system, and the purification qualities of the recovered water. The chemical pretreatment of the shower water for microorganism control involved activated carbon, mixed ion exchange resin beds, and iodine bactericide dispensing units. The water was recycled five times, demonstrating the feasibility of reuse.

  3. Exposure Modeling of Residential Air Exchange Rates for NEXUS Participants

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improv...

  4. Exposure Modeling of Residential Air Exchange Rates for NEXUS Participants.

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improv...

  5. Reconstructing Exposures from Biomarkers using Exposure-Pharmacokinetic Modeling - A Case Study with Carbaryl

    EPA Science Inventory

    Sources of uncertainty involved in exposure reconstruction for a short half-life chemical, carbaryl, were characterized using the Cumulative and Aggregate Risk Evaluation System (CARES), an exposure model, and a human physiologically based pharmacokinetic (PBPK) model. CARES was...

  6. Exposure Space: Integrating Exposure Data and Modeling with Toxicity Information

    EPA Science Inventory

    Recent advances have been made in high-throughput (HTP) toxicity testing, e.g. from ToxCast, which will ultimately be combined with HTP predictions of exposure potential to support next-generation chemical safety assessment. Rapid exposure methods are essential in selecting chemi...

  7. CAMS confirmation of previously reported meteor showers

    NASA Astrophysics Data System (ADS)

    Jenniskens, P.; Nénon, Q.; Gural, P. S.; Albers, J.; Haberman, B.; Johnson, B.; Holman, D.; Morales, R.; Grigsby, B. J.; Samuels, D.; Johannink, C.

    2016-03-01

    Leading up to the 2015 IAU General Assembly, the International Astronomical Union's Working List of Meteor Showers included 486 unconfirmed showers, showers that are not certain to exist. If confirmed, each shower would provide a record of past comet or asteroid activity. Now, we report that 41 of these are detected in the Cameras for Allsky Meteor Surveillance (CAMS) video-based meteor shower survey. They manifest as meteoroids arriving at Earth from a similar direction and orbit, after removing the daily radiant drift due to Earth's motion around the Sun. These showers do exist and, therefore, can be moved to the IAU List of Established Meteor Showers. This adds to 31 previously confirmed showers from CAMS data. For each shower, finding charts are presented based on 230,000 meteors observed up to March of 2015, calculated by re-projecting the drift-corrected Sun-centered ecliptic coordinates into more familiar equatorial coordinates. Showers that are not detected, but should have, and duplicate showers that project to the same Sun-centered ecliptic coordinates, are recommended for removal from the Working List.

  8. POPULATION EXPOSURES TO PARTICULATE MATTER: A COMPARISON OF EXPOSURE MODEL PREDICTIONS AND MEASUREMENT DATA

    EPA Science Inventory

    The US EPA National Exposure Research Laboratory (NERL) is currently developing an integrated human exposure source-to-dose modeling system (HES2D). This modeling system will incorporate models that use a probabilistic approach to predict population exposures to environmental ...

  9. Operation of the computer model for microenvironment atomic oxygen exposure

    NASA Technical Reports Server (NTRS)

    Bourassa, R. J.; Gillis, J. R.; Gruenbaum, P. E.

    1995-01-01

    A computer model for microenvironment atomic oxygen exposure has been developed to extend atomic oxygen modeling capability to include shadowing and reflections. The model uses average exposure conditions established by the direct exposure model and extends the application of these conditions to treat surfaces of arbitrary shape and orientation.

  10. Monte Carlo Shower Counter Studies

    NASA Technical Reports Server (NTRS)

    Snyder, H. David

    1991-01-01

    Activities and accomplishments related to the Monte Carlo shower counter studies are summarized. A tape of the VMS version of the GEANT software was obtained and installed on the central computer at Gallaudet University. Due to difficulties encountered in updating this VMS version, a decision was made to switch to the UNIX version of the package. This version was installed and used to generate the set of data files currently accessed by various analysis programs. The GEANT software was used to write files of data for positron and proton showers. Showers were simulated for a detector consisting of 50 alternating layers of lead and scintillator. Each file consisted of 1000 events at each of the following energies: 0.1, 0.5, 2.0, 10, 44, and 200 GeV. Data analysis activities related to clustering, chi square, and likelihood analyses are summarized. Source code for the GEANT user subprograms and data analysis programs are provided along with example data plots.

  11. DIETARY EXPOSURES OF YOUNG CHILDREN, PART 3: MODELLING

    EPA Science Inventory

    A deterministic model was used to model dietary exposure of young children. Parameters included pesticide residue on food before handling, surface pesticide loading, transfer efficiencies and children's activity patterns. Three components of dietary pesticide exposure were includ...

  12. EXPOSURE ANALYSIS MODELING SYSTEM (EXAMS): USER MANUAL AND SYSTEM DOCUMENTATION

    EPA Science Inventory

    The Exposure Analysis Modeling System, first published in 1982 (EPA-600/3-82-023), provides interactive computer software for formulating aquatic ecosystem models and rapidly evaluating the fate, transport, and exposure concentrations of synthetic organic chemicals - pesticides, ...

  13. Meteor Shower Forecast Improvements from a Survey of All-Sky Network Observations

    NASA Technical Reports Server (NTRS)

    Moorhead, Althea V.; Sugar, Glenn; Brown, Peter G.; Cooke, William J.

    2015-01-01

    Meteoroid impacts are capable of damaging spacecraft and potentially ending missions. In order to help spacecraft programs mitigate these risks, NASA's Meteoroid Environment Office (MEO) monitors and predicts meteoroid activity. Temporal variations in near-Earth space are described by the MEO's annual meteor shower forecast, which is based on both past shower activity and model predictions. The MEO and the University of Western Ontario operate sister networks of all-sky meteor cameras. These networks have been in operation for more than 7 years and have computed more than 20,000 meteor orbits. Using these data, we conduct a survey of meteor shower activity in the "fireball" size regime using DBSCAN. For each shower detected in our survey, we compute the date of peak activity and characterize the growth and decay of the shower's activity before and after the peak. These parameters are then incorporated into the annual forecast for an improved treatment of annual activity.

  14. A possible new shower on Eridanus-Orion border

    NASA Astrophysics Data System (ADS)

    Šegon, Damir; Gural, Peter; Andreić, Željko; Vida, Denis; Skokić, Ivica; Novoselnik, Filip; Gržinić, Luciano

    2014-02-01

    Three showers on the border between constellations of Eridanus and Orion were found during extensive search for new showers in SonotaCo and CMN video meteor orbit databases. Our results suggest that two of these three showers represent  Eridanids shower (337 NUE), while third one represents separate possible new shower which has been named 6 Orionids (552 PSO).

  15. The Daytime Craterids, a radar-detected meteor shower outburst from hyperbolic comet C/2007 W1 (Boattini)

    NASA Astrophysics Data System (ADS)

    Wiegert, P. A.; Brown, P. G.; Weryk, R. J.; Wong, D. K.

    2011-06-01

    We report a new daytime meteor shower detected with the Canadian Meteor Orbit Radar (CMOR). This shower has a radiant in the southern constellation Crater. The Daytime Craterid shower was observed in 2003 and 2008 but not in any of the other years in the 2002-09 interval. The strength of this shower in the years observed is equivalent to a daily averaged zenithal hourly rate (ZHR) over 30, with a peak ZHR likely much higher at the time of the outburst. The orbital elements of the shower closely match those of Comet C/2007 W1 (Boattini), which passed perihelion in 2007. The orbit of C/2007 W1 is nominally hyperbolic orbit making this the first meteor shower detected from a clearly unbound comet. The 2003 outburst of the Daytime Craterid shower indicates that this comet must have recently been transferred to an unbound orbit from a bound one, likely through a close encounter with a giant planet. As a result we conclude that this shower provides us with one of the few examples of showers originating from the population of nearly isotropic comets. The stream is difficult to model owing to its proximity to the orbits of Jupiter, Saturn and the Earth. However, the intermittent nature of the shower can be largely understood from numerical simulations. No outbursts of similar strength are expected in the next decade, with the possible exception of 2015.

  16. Modeling Impaired Hippocampal Neurogenesis after Radiation Exposure.

    PubMed

    Cacao, Eliedonna; Cucinotta, Francis A

    2016-03-01

    Radiation impairment of neurogenesis in the hippocampal dentate gyrus is one of several factors associated with cognitive detriments after treatment of brain cancers in children and adults with radiation therapy. Mouse models have been used to study radiation-induced changes in neurogenesis, however the models are limited in the number of doses, dose fractions, age and time after exposure conditions that have been studied. The purpose of this study is to develop a novel predictive mathematical model of radiation-induced changes to neurogenesis using a system of nonlinear ordinary differential equations (ODEs) to represent the time, age and dose-dependent changes to several cell populations participating in neurogenesis as reported in mouse experiments exposed to low-LET radiation. We considered four compartments to model hippocampal neurogenesis and, consequently, the effects of radiation treatment in altering neurogenesis: (1) neural stem cells (NSCs), (2) neuronal progenitor cells or neuroblasts (NB), (3) immature neurons (ImN) and (4) glioblasts (GB). Because neurogenesis is decreasing with increasing mouse age, a description of the age-related dynamics of hippocampal neurogenesis is considered in the model, which is shown to be an important factor in comparisons to experimental data. A key feature of the model is the description of negative feedback regulation on early and late neuronal proliferation after radiation exposure. The model is augmented with parametric descriptions of the dose and time after irradiation dependences of activation of microglial cells and a possible shift of NSC proliferation from neurogenesis to gliogenesis reported at higher doses (∼10 Gy). Predictions for dose-fractionation regimes and for different mouse ages, and prospects for future work are then discussed.

  17. Modeling Impaired Hippocampal Neurogenesis after Radiation Exposure.

    PubMed

    Cacao, Eliedonna; Cucinotta, Francis A

    2016-03-01

    Radiation impairment of neurogenesis in the hippocampal dentate gyrus is one of several factors associated with cognitive detriments after treatment of brain cancers in children and adults with radiation therapy. Mouse models have been used to study radiation-induced changes in neurogenesis, however the models are limited in the number of doses, dose fractions, age and time after exposure conditions that have been studied. The purpose of this study is to develop a novel predictive mathematical model of radiation-induced changes to neurogenesis using a system of nonlinear ordinary differential equations (ODEs) to represent the time, age and dose-dependent changes to several cell populations participating in neurogenesis as reported in mouse experiments exposed to low-LET radiation. We considered four compartments to model hippocampal neurogenesis and, consequently, the effects of radiation treatment in altering neurogenesis: (1) neural stem cells (NSCs), (2) neuronal progenitor cells or neuroblasts (NB), (3) immature neurons (ImN) and (4) glioblasts (GB). Because neurogenesis is decreasing with increasing mouse age, a description of the age-related dynamics of hippocampal neurogenesis is considered in the model, which is shown to be an important factor in comparisons to experimental data. A key feature of the model is the description of negative feedback regulation on early and late neuronal proliferation after radiation exposure. The model is augmented with parametric descriptions of the dose and time after irradiation dependences of activation of microglial cells and a possible shift of NSC proliferation from neurogenesis to gliogenesis reported at higher doses (∼10 Gy). Predictions for dose-fractionation regimes and for different mouse ages, and prospects for future work are then discussed. PMID:26943452

  18. Composition of primary cosmic rays near the bend from a study of hadrons in air showers at sea level

    NASA Technical Reports Server (NTRS)

    Mincer, A. I.; Freudenreich, H. T.; Goodman, J. A.; Tonwar, S. C.; Yodh, G. B.; Ellsworth, R. W.; Berley, D.

    1985-01-01

    Data on hadrons in air showers arriving at sea level were studied to find sensitivity to primary cosmic ray composition. The rate of showers which satisfy minimum shower density and hadron energy requirements as well as the rate of showers containing hadrons delayed with respect to the electron shower front are compared to Monte Carlo simulations. The data on the rate of total triggers and delayed hadrons are compared to predicted rates for two models of primary composition. The data are consistent with models which require an increasing heavy nuclei fraction near 10 to the 15th power eV. The spectra which are consistent with the observed rate are also compared to the observed shower size spectrum at sea level and mountain level.

  19. Measure Guideline: Water Management at Tub and Shower Assemblies

    SciTech Connect

    Dickson, B.

    2011-12-01

    Due to the high concentrations of water and the consequential risk of water damage to the home's structure a comprehensive water management system is imperative to protect the building assemblies underlying the finish surround of tub and shower areas. This guide shows how to install fundamental waterproofing strategies to prevent water related issues at shower and tub areas. When conducting a total gut rehab of a structure or constructing a new home, best practice installation and detailing for effective waterproofing are critically important at bathtub and shower assemblies. Water management issues in a structure may go unrecognized for long periods, so that when they are finally observed, the damage from long-term water exposure is extensive. A gut rehab is often undertaken when a home has experienced a natural disaster or when the homeowners are interested in converting an old, high-energy-use building into a high-quality, efficient structure that meets or exceeds one of the national energy standards, such as ENERGY STAR or LEED for homes. During a gut rehab, bath areas need to be replaced with diligent attention to detail. Employing effective water management practices in the installation and detailing of tub and shower assemblies will minimize or eliminate water issues within the building cavities and on the finished surfaces. A residential tub-and-shower surround or shower-stall assembly is designed to handle a high volume of water - 2.5 gallons per minute, with multiple baths occurring during a typical day. Transitions between dissimilar materials and connections between multiple planes must be installed with care to avoid creating a pathway for water to enter the building assemblies. Due to the high volume of water and the consequential risk of water damage to the home's structure, a comprehensive water management system is imperative to protect the building assemblies underlying the finish surround of tub and shower areas. At each stage of construction

  20. Fast Shower Simulation in the ATLAS Calorimeter

    SciTech Connect

    Barberio, E.; Boudreau, J.; Butler, B.; Cheung, S.L.; Dell'Acqua, A.; Di Simone, A.; Ehrenfeld, W.; Gallas, M.V.; Glazov, A.; Marshall, Z.; Mueller, J.; Placakyte, R.; Rimoldi, A.; Savard, P.; Tsulaia, V.; Waugh, A.; Young, C.C.; /SLAC

    2011-11-08

    The time to simulate pp collisions in the ATLAS detector is largely dominated by the showering of electromagnetic particles in the heavy parts of the detector, especially the electromagnetic barrel and endcap calorimeters. Two procedures have been developed to accelerate the processing time of electromagnetic particles in these regions: (1) a fast shower parameterisation and (2) a frozen shower library. Both work by generating the response of the calorimeter to electrons and positrons with Geant 4, and then reintroduce the response into the simulation at runtime. In the fast shower parameterisation technique, a parameterization is tuned to single electrons and used later by simulation. In the frozen shower technique, actual showers from low-energy particles are used in the simulation. Full Geant 4 simulation is used to develop showers down to {approx} 1 GeV, at which point the shower is terminated by substituting a frozen shower. Judicious use of both techniques over the entire electromagnetic portion of the ATLAS calorimeter produces an important improvement of CPU time. We discuss the algorithms and their performance in this paper.

  1. A POPULATION EXPOSURE MODEL FOR PARTICULATE MATTER: SHEDS-PM

    EPA Science Inventory

    The US EPA National Exposure Research Laboratory (NERL) has developed a population exposure and dose model for particulate matter (PM) that will be publicly available in Fall 2002. The Stochastic Human Exposure and Dose Simulation (SHEDS-PM) model uses a probabilistic approach ...

  2. A NEW METHOD OF LONGITUDINAL DIARY ASSEMBLY FOR EXPOSURE MODELING

    EPA Science Inventory

    Many stochastic human exposure models require the construction of longitudinal time-activity diaries to evaluate the time sequence of concentrations encountered, and hence, the pollutant exposure for the simulated individuals. However, most of the available data on human activiti...

  3. A PROBABILISTIC MODELING FRAMEWORK FOR PREDICTING POPULATION EXPOSURES TO BENZENE

    EPA Science Inventory

    The US Environmental Protection Agency (EPA) is modifying their probabilistic Stochastic Human Exposure Dose Simulation (SHEDS) model to assess aggregate exposures to air toxics. Air toxics include urban Hazardous Air Pollutants (HAPS) such as benzene from mobile sources, part...

  4. Evaluating Rapid Models for High-Throughput Exposure Forecasting (SOT)

    EPA Science Inventory

    High throughput exposure screening models can provide quantitative predictions for thousands of chemicals; however these predictions must be systematically evaluated for predictive ability. Without the capability to make quantitative, albeit uncertain, forecasts of exposure, the ...

  5. Parton shower evolution in a 3D hydrodynamical medium

    SciTech Connect

    Renk, Thorsten

    2008-09-15

    We present a Monte Carlo simulation of the perturbative quantum chromodynamics shower developing after a hard process embedded in a heavy-ion collision. The main assumption is that the cascade of branching partons traverses a medium that (consistent with standard radiative energy loss pictures) is characterized by a local transport coefficient q-circumflex that measures the virtuality per unit length transferred to a parton that propagates in this medium. This increase in parton virtuality alters the development of the shower and in essence leads to extra induced radiation and hence a softening of the momentum distribution in the shower. After hadronization, this leads to the concept of a medium-modified fragmentation function. On the level of observables, this is manifest as the suppression of high-transverse-momentum (P{sub T}) hadron spectra. We simulate the soft medium created in heavy-ion collisions by a 3D hydrodynamical evolution and average the medium-modified fragmentation function over this evolution to compare with data on single inclusive hadron suppression and extract the q-circumflex that characterizes the medium. Finally, we discuss possible uncertainties of the model formulation and argue that the data in a soft momentum show evidence of qualitatively different physics that presumably cannot be described by a medium-modified parton shower.

  6. Don Quixote --- a possible parent body of a meteor shower

    NASA Astrophysics Data System (ADS)

    Rudawska, R.; Vaubaillon, J.

    2014-07-01

    This talk addresses the topic of meteoroid stream parent body in relation to meteor showers observed on the Earth. We carry out a further search to investigate the possibility of meteor shower observations caused by particles ejected from (3552) Don Quixote. The (3552) Don Quixote asteroid was discovered in 1983 as an Amor asteroid. The Tisserand parameter for the orbit has a value of 2.315 with respect to Jupiter, which indicates a comet-like orbit. The diameter of the object calculated from the absolute magnitude, is in the range of 12.3--24.5 km. It all makes Don Quixote a good candidate for a short-period comet among known near-Earth objects, which the recently observed cometary activity confirms [1]. We have investigated the orbital evolution of the meteoroid stream originated from Don Quixote. If the object was active in the past, it might be a parent body for a meteor shower observed on the Earth. The model for the generation and evolution of the meteoroid stream in the Solar System is taken from [2]. The asteroid's orbital elements and physical properties are taken from the JPL horizons website. The ejections of meteoroids from the asteroid surface took place when the asteroid was passing its perihelion between 5000 B.C. and 2013 A.D. Next, the orbits of ejected meteoroids were integrated to the year 2050. If a meteoroid is sufficiently close to the Earth, its orbital parameters are saved and compared with known showers.

  7. HUMAN EXPOSURE MODELING: CONCEPTS, METHODS, AND TOOLS

    EPA Science Inventory

    Understanding human exposure is critical when estimating the occurrence of deleterious effects that could follow contact with environmental contaminants. For many pollutants, the intensity, duration, frequency, route, and timing of exposure is highly variable, particularly whe...

  8. Extensive Air Showers in the Classroom

    ERIC Educational Resources Information Center

    Badala, A.; Blanco, F.; La Rocca, P.; Pappalardo, G. S.; Pulvirenti, A.; Riggi, F.

    2007-01-01

    The basic properties of extensive air showers of particles produced in the interaction of a high-energy primary cosmic ray in the Earth's atmosphere are discussed in the context of educational cosmic ray projects involving undergraduate students and high-school teams. Simulation results produced by an air shower development code were made…

  9. Search for excess showers from Crab Nebula

    NASA Technical Reports Server (NTRS)

    Kirov, I. N.; Stamenov, J. N.; Ushev, S. Z.; Janminchev, V. D.; Aseikin, V. S.; Nikolsky, S. I.; Nikolskaja, N. M.; Yakovlev, V. I.; Morozov, A. E.

    1985-01-01

    The arrival directions of muon poor showers registrated in the Tien Shan experiment during an effective running time about I,8.IO(4)h were analyzed. It is shown that there is a significant excess of these showers coming the direction of Crab Nebula.

  10. Meteor showers associated with 2003EH1

    NASA Astrophysics Data System (ADS)

    Babadzhanov, P. B.; Williams, I. P.; Kokhirova, G. I.

    2008-06-01

    Using the Everhart RADAU19 numerical integration method, the orbital evolution of the near-Earth asteroid 2003EH1 is investigated. This asteroid belongs to the Amor group and is moving on a comet-like orbit. The integrations are performed over one cycle of variation of the perihelion argument ω. Over such a cycle, the orbit intersect that of the Earth at eight different values of ω. The orbital parameters are different at each of these intersections and so a meteoroid stream surrounding such an orbit can produce eight different meteor showers, one at each crossing. The geocentric radiants and velocities of the eight theoretical meteor showers associated with these crossing points are determined. Using published data, observed meteor showers are identified with each of the theoretically predicted showers. The character of the orbit and the existence of observed meteor showers associated with 2003EH1 confirm the supposition that this object is an extinct comet.

  11. Meteor Shower Identification and Characterization with Python

    NASA Technical Reports Server (NTRS)

    Moorhead, Althea

    2015-01-01

    The short development time associated with Python and the number of astronomical packages available have led to increased usage within NASA. The Meteoroid Environment Office in particular uses the Python language for a number of applications, including daily meteor shower activity reporting, searches for potential parent bodies of meteor showers, and short dynamical simulations. We present our development of a meteor shower identification code that identifies statistically significant groups of meteors on similar orbits. This code overcomes several challenging characteristics of meteor showers such as drastic differences in uncertainties between meteors and between the orbital elements of a single meteor, and the variation of shower characteristics such as duration with age or planetary perturbations. This code has been proven to successfully and quickly identify unusual meteor activity such as the 2014 kappa Cygnid outburst. We present our algorithm along with these successes and discuss our plans for further code development.

  12. Application of statistical modeling to occupational exposure assessment

    SciTech Connect

    Nicas, M.

    1991-01-01

    This dissertation applies statistical modeling to two problems: (1) describing a single worker's exposure distribution and estimating its associated arithemetic mean; and (2) describing the distribution of inhalation exposure levels among a population of respirator wearers while accounting for variability in ambient exposure and respirator penetration values within and between wearers. A task-based statistical construct for a single worker's exposure levels for a single agent is developed; the model accounts for variability in short-term time weighted average (TWA) exposure values within a task, and for variability in arithmetic mean exposure levels between tasks. Five sample survey designs for estimating a worker's arithmetic mean exposure level are examined. Stratified random sampling designs, in which short-term TWAs are measured for time periods selected on a task basis, can provide a more precise estimate of the arithmetic mean exposure level than the traditional survey design for the same fixed cost. For describing inhalation exposure levels (C{sub i}) among a population of air-purifying respirator wearers, a synthesis of lognormal one-way analysis of variance models for ambient exposure levels (C.) and respirator penetration (P) values provides the most tractable construct. The model is applied to assessing the risk of toxicant overexposure for a respirator wearer population. Overexposure to a chronic toxicant is equated with an arithmetic mean exposure level above the permissible exposure limit (PEL) value, while overexposure to an acute toxicant is equated with a 95th percentile exposure level above the PEL value.

  13. Don Quixote-A possible parent body of a meteor shower

    NASA Astrophysics Data System (ADS)

    Rudawska, Regina; Vaubaillon, Jeremie

    2015-12-01

    Asteroid 3552 Don Quixote (1983 SA) orbits the Sun on an orbit that resembles that of a short-period comet. This, together with its recently observed cometary activity, makes it a good candidate for a parent body of a meteor shower. Model calculations show that the particles originated from Don Quixote pass close enough to Earth orbit to search for a meteor shower activity. Corresponding meteor showers were found in CAMS (Rudawska and Jenniskens, 2014) and EDMOND (Kornoš et al., 2014) video observations. The κ Lyrids and August μ Draconids (IAU#464 and IAU#470, respectively), a similarly inclined stream active in the summer, are associated with 3552 Don Quixote.

  14. Searching for mini black holes signatures in cosmic rays air shower

    SciTech Connect

    Lamri, S.; Kalli, S.; Mimouni, J.

    2012-06-27

    Theories with extra dimensions at low Planck scale, offer the exciting possibility of mini black holes production in ultra high-energy particles interactions. In particular, cosmic neutrinos interaction can produce black holes deep in the Earth's atmosphere. These mini black holes then decay and produce 'characteristic' air showers. In this paper, we examine the properties of the mini black holes (mBH) air showers and compare them to the standard model (mSM) ones. We point out to some possible criteria that help distinguishing mBH air showers.

  15. DEVELOPMENT OF A DIETARY EXPOSURE POTENTIAL MODEL FOR EVALUATING DIETARY EXPOSURE TO CHEMICAL RESIDUES IN FOOD

    EPA Science Inventory

    The Dietary Exposure Potential Model (DEPM) is a computer-based model developed for estimating dietary exposure to chemical residues in food. The DEPM is based on food consumption data from the 1987-1988 Nationwide Food Consumption Survey (NFCS) administered by the United States ...

  16. Extraction of exposure modeling parameters of thick resist

    NASA Astrophysics Data System (ADS)

    Liu, Chi; Du, Jinglei; Liu, Shijie; Duan, Xi; Luo, Boliang; Zhu, Jianhua; Guo, Yongkang; Du, Chunlei

    2004-12-01

    Experimental and theoretical analysis indicates that many nonlinear factors existing in the exposure process of thick resist can remarkably affect the PAC concentration distribution in the resist. So the effects should be fully considered in the exposure model of thick resist, and exposure parameters should not be treated as constants because there exists certain relationship between the parameters and resist thickness. In this paper, an enhanced Dill model for the exposure process of thick resist is presented, and the experimental setup for measuring exposure parameters of thick resist is developed. We measure the intensity transmittance curve of thick resist AZ4562 under different processing conditions, and extract the corresponding exposure parameters based on the experiment results and the calculations from the beam propagation matrix of the resist films. With these modified modeling parameters and enhanced Dill model, simulation of thick-resist exposure process can be effectively developed in the future.

  17. Neutrons in extensive air showers

    SciTech Connect

    Stenkin, Yu. V.; Djappuev, D. D.; Valdes-Galicia, J. F.

    2007-06-15

    The main properties of the so-called neutron bursts produced by the passage of extensive air showers (EASs) through a detector array and the properties of these EASs are considered using the experiments that are being or have been carried out previously with the Carpet-2 array at Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences, and at Cosmic-Ray Station of UNAM in Mexico as examples. We show that no exotic processes are required to explain the nature of neutron bursts. Based on a working prototype of the previously proposed MULTICOM array, we also show that this phenomenon can be successfully used in studying the EAS hadronic component and that adding special thermal neutron detectors can improve significantly the capabilities of the array for EAS study.

  18. Space Weathering of Leonid Shower Meteoroids

    NASA Astrophysics Data System (ADS)

    Jenniskens, P.

    2002-12-01

    When comets are exposed to solar radiation, they emit dust particles that rapidly disperse in the interplanetary medium. There, they experience weathering due to heating and cooling cycles, solar wind implantation, and collisions. The result is to facilitate breakup of the grains, make the remaining units more (or less) cohesive, and change the volatile element contribution (sodium containing minerals and organics). The breakup of grains is evident in the presence of meteor clusters during meteor showers. Spectacular examples have recently been detected during Leonid storms. These are particularly interesting for understanding space weathering of solid surfaces, because the epoch of ejection of the grains and the duration of exposure to the interplanetary medium is known. All are from very recent returns of the parent comet to perihelion. In addition, the sputtering of meteoroids by air molecules during entry in the Earth's atmosphere may be a usefull analog in understanding the source of the sodium atmosphere of the Moon and Mercury. In certain conditions, an early release of sodium is observed. Results from NASA's Leonid Multi-Instrument Aircraft Campaign (Leonid MAC) and ground based Leonid storm observations will be discussed in this context. First results from the recent November 2002 Leonid MAC mission will be shown.

  19. Studies of Cosmic Ray Composition and Air Shower Structure with the Pierre Auger Observatory

    SciTech Connect

    Abraham, : J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E.J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.

    2009-06-01

    These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Measurement of the average depth of shower maximum and its fluctuations with the Pierre Auger Observatory; (2) Study of the nuclear mass composition of UHECR with the surface detectors of the Pierre Auger Observatory; (3) Comparison of data from the Pierre Auger Observatory with predictions from air shower simulations: testing models of hadronic interactions; (4) A Monte Carlo exploration of methods to determine the UHECR composition with the Pierre Auger Observatory; (5) The delay of the start-time measured with the Pierre Auger Observatory for inclined showers and a comparison of its variance with models; (6) UHE neutrino signatures in the surface detector of the Pierre Auger Observatory; and (7) The electromagnetic component of inclined air showers at the Pierre Auger Observatory.

  20. Exposure-Based Cat Modeling, Available data, Advantages, & Limitations

    NASA Astrophysics Data System (ADS)

    Michel, Gero; Hosoe, Taro; Schrah, Mike; Saito, Keiko

    2010-05-01

    This paper discusses the advantages and disadvantages of exposure data for cat-modeling and considers concepts of scale as well as the completeness of data and data scoring using field/model examples. Catastrophe modeling based on exposure data has been considered the panacea for insurance-related cat modeling since the late 1980's. Reasons for this include: • The ability to extend risk modeling to consider data beyond historical losses, • Usability across many relevant scales, • Flexibility in addressing complex structures and policy conditions, and • Ability to assess dependence of risk results on exposure-attributes and exposure-modifiers, such as lines of business, occupancy types, and mitigation features, at any given scale. In order to calculate related risk, monetary exposure is correlated to vulnerabilities that have been calibrated with historical results, plausibility concepts, and/or physical modeling. While exposure based modeling is widely adopted, we also need to be aware of its limitations which include: • Boundaries in our understanding of the distribution of exposure, • Spatial interdependence of exposure patterns and the time-dependence of exposure, • Incomplete availability of loss information to calibrate relevant exposure attributes/structure with related vulnerabilities and losses, • The scale-dependence of vulnerability, • Potential for missing or incomplete communication of assumptions made during model calibration, • Inefficiencies in the aggregation or disaggregation of vulnerabilities, and • Factors which can influence losses other than exposure, vulnerability, and hazard. Although we might assume that the higher the resolution the better, regional model calibration is often limited to lower than street level resolution with higher resolution being achieved by disaggregating results using topographic/roughness features with often loosely constrained and/or varying effects on losses. This suggests that higher accuracy

  1. A possible new shower on Eridanus-Orion border

    NASA Astrophysics Data System (ADS)

    Šegon, Damir; Gural, Peter; Andreić, Željko; Vida, Denis; Skokić, Ivica; Novoselnik, Filip; Gržinić, Luciano

    2014-12-01

    Three showers on the border between constelations of Eridanus and Orion were found during extensive search for new showers in SonotaCo and CMN video meteor orbit databases. Our results suggest that two of them represent ν Eridanids shower (337 NUE), while third one represents possible new shower which has been named π^6 Orionids (552 PSO).

  2. High energy hadrons in extensive air showers

    NASA Technical Reports Server (NTRS)

    Tonwar, S. C.

    1985-01-01

    Experimental data on the high energy hadronic component in extensive air showers of energies approx. 10 to the 14 to 10 to the 16 eV when compared with expectations from Monte Carlo simulations have shown the observed showers to be deficient in high energy hadrons relative to simulated showers. An attempt is made to understand these anomalous features with more accurate comparison of observations with expectations, taking into account the details of the experimental system. Results obtained from this analysis and their implications for the high energy physics of particle interactions at energy approx. 10 to the 15 eV are presented.

  3. Modelling anxiety disorders following chemical exposures.

    PubMed

    Adamec, R

    1994-01-01

    The effects of kindling and inverse benzodiazepine receptor agonist beta-carbolines on animal models of anxiety are briefly reviewed in relation to affective disorder associated with chemical exposure. Recent experimental results are described. In the present study, cats were given the inverse benzodiazepine receptor agonist, FG-7142, a powerful anxiogenic compound in humans and animals. Neural transmission in pathways involved in defensive behavior in the cat was monitored using evoked potential techniques. Change in these pathways was related to behavioral changes induced by the drug. It was found that a single dose of FG-7142 lastingly increased defensive response to rodents for at least 40 days after drug administration. Behavioral change was specific to defensive response, since approach-attack behavior remained unchanged, replicating previous studies. The benzodiazepine receptor antagonist, Flumazenil, reversed the increase in defensiveness in a drug-dependent manner, replicating previous findings. Increased defensiveness was paralleled by a delayed onset potentiation of neural transmission between the amygdala and the medial hypothalamus of the left hemisphere. Potentiation in the left hemisphere was transient, decaying between 6 and 12 days after the drug. There was a longer lasting potentiation (LTP) of activity evoked in the left and right amygdalo-periacqueductal gray pathways and in the right amygdalo-medial hypothalamic pathway. Potentiation in these pathways appeared at the time of behavioral change. Potentiation of the right amygdalo-periacqueductal gray and right amygdalo-medial hypothalamic pathways persisted until the end of the experiment. In contrast, potentiation of the left amygdalo-periacqueductal gray pathway faded by 40 days after the drug. Flumazenil decreased potentiation ony in the right amygdalo-periacqueductal gray pathway. These data strongly suggest that lasting affective change is mediated by lasting changes in particular efferents

  4. Hadronic Shower Validation Experience for the ATLAS End-Cap Calorimeter

    NASA Astrophysics Data System (ADS)

    Kiryunin, A. E.; Salihagić, D.

    2007-03-01

    Validation of GEANT4 hadronic physics models is carried out by comparing experimental data from beam tests of modules of the ATLAS end-cap calorimeters with GEANT4 based simulations. Two physics lists (LHEP and QGSP) for the simulation of hadronic showers are evaluated. Calorimeter performance parameters like the energy resolution and response for charged pions and shapes of showers are studied. Comparison with GEANT3 predictions is done as well.

  5. Probing Atmospheric Electric Fields in Thunderstorms through Radio Emission from Cosmic-Ray-Induced Air Showers.

    PubMed

    Schellart, P; Trinh, T N G; Buitink, S; Corstanje, A; Enriquez, J E; Falcke, H; Hörandel, J R; Nelles, A; Rachen, J P; Rossetto, L; Scholten, O; Ter Veen, S; Thoudam, S; Ebert, U; Koehn, C; Rutjes, C; Alexov, A; Anderson, J M; Avruch, I M; Bentum, M J; Bernardi, G; Best, P; Bonafede, A; Breitling, F; Broderick, J W; Brüggen, M; Butcher, H R; Ciardi, B; de Geus, E; de Vos, M; Duscha, S; Eislöffel, J; Fallows, R A; Frieswijk, W; Garrett, M A; Grießmeier, J; Gunst, A W; Heald, G; Hessels, J W T; Hoeft, M; Holties, H A; Juette, E; Kondratiev, V I; Kuniyoshi, M; Kuper, G; Mann, G; McFadden, R; McKay-Bukowski, D; McKean, J P; Mevius, M; Moldon, J; Norden, M J; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Reich, W; Röttgering, H; Scaife, A M M; Schwarz, D J; Serylak, M; Smirnov, O; Steinmetz, M; Swinbank, J; Tagger, M; Tasse, C; Toribio, M C; van Weeren, R J; Vermeulen, R; Vocks, C; Wise, M W; Wucknitz, O; Zarka, P

    2015-04-24

    We present measurements of radio emission from cosmic ray air showers that took place during thunderstorms. The intensity and polarization patterns of these air showers are radically different from those measured during fair-weather conditions. With the use of a simple two-layer model for the atmospheric electric field, these patterns can be well reproduced by state-of-the-art simulation codes. This in turn provides a novel way to study atmospheric electric fields.

  6. Hadronic Shower Validation Experience for the ATLAS End-Cap Calorimeter

    SciTech Connect

    Kiryunin, A. E.; Salihagic, D.

    2007-03-19

    Validation of GEANT4 hadronic physics models is carried out by comparing experimental data from beam tests of modules of the ATLAS end-cap calorimeters with GEANT4 based simulations. Two physics lists (LHEP and QGSP) for the simulation of hadronic showers are evaluated. Calorimeter performance parameters like the energy resolution and response for charged pions and shapes of showers are studied. Comparison with GEANT3 predictions is done as well.

  7. Probing Atmospheric Electric Fields in Thunderstorms through Radio Emission from Cosmic-Ray-Induced Air Showers.

    PubMed

    Schellart, P; Trinh, T N G; Buitink, S; Corstanje, A; Enriquez, J E; Falcke, H; Hörandel, J R; Nelles, A; Rachen, J P; Rossetto, L; Scholten, O; Ter Veen, S; Thoudam, S; Ebert, U; Koehn, C; Rutjes, C; Alexov, A; Anderson, J M; Avruch, I M; Bentum, M J; Bernardi, G; Best, P; Bonafede, A; Breitling, F; Broderick, J W; Brüggen, M; Butcher, H R; Ciardi, B; de Geus, E; de Vos, M; Duscha, S; Eislöffel, J; Fallows, R A; Frieswijk, W; Garrett, M A; Grießmeier, J; Gunst, A W; Heald, G; Hessels, J W T; Hoeft, M; Holties, H A; Juette, E; Kondratiev, V I; Kuniyoshi, M; Kuper, G; Mann, G; McFadden, R; McKay-Bukowski, D; McKean, J P; Mevius, M; Moldon, J; Norden, M J; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Reich, W; Röttgering, H; Scaife, A M M; Schwarz, D J; Serylak, M; Smirnov, O; Steinmetz, M; Swinbank, J; Tagger, M; Tasse, C; Toribio, M C; van Weeren, R J; Vermeulen, R; Vocks, C; Wise, M W; Wucknitz, O; Zarka, P

    2015-04-24

    We present measurements of radio emission from cosmic ray air showers that took place during thunderstorms. The intensity and polarization patterns of these air showers are radically different from those measured during fair-weather conditions. With the use of a simple two-layer model for the atmospheric electric field, these patterns can be well reproduced by state-of-the-art simulation codes. This in turn provides a novel way to study atmospheric electric fields. PMID:25955053

  8. PROBABILISTIC MODELING FOR ADVANCED HUMAN EXPOSURE ASSESSMENT

    EPA Science Inventory

    Human exposures to environmental pollutants widely vary depending on the emission patterns that result in microenvironmental pollutant concentrations, as well as behavioral factors that determine the extent of an individual's contact with these pollutants. Probabilistic human exp...

  9. 49 CFR 228.321 - Showering facilities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... provided with hot and cold water feeding a common discharge line. (3) Unless otherwise provided by a... and cold running potable water must be provided for showering purposes. The water supplied to a...

  10. 49 CFR 228.321 - Showering facilities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... provided with hot and cold water feeding a common discharge line. (3) Unless otherwise provided by a... and cold running potable water must be provided for showering purposes. The water supplied to a...

  11. MODELING ENVIRONMENTAL EXPOSURES TO PARTICULATE MATTER AND PESTICIDES

    EPA Science Inventory

    This presentation describes initial results from on-going research at EPA on modeling human exposures to particulate matter and residential pesticides. A first generation probabilistic population exposure model for Particulate Matter (PM), specifically for predicting PM1o and P...

  12. USEPA SHEDS MODEL: METHODOLOGY FOR EXPOSURE ASSESSMENT FOR WOOD PRESERVATIVES

    EPA Science Inventory

    A physically-based, Monte Carlo probabilistic model (SHEDS-Wood: Stochastic Human Exposure and Dose Simulation model for wood preservatives) has been applied to assess the exposure and dose of children to arsenic (As) and chromium (Cr) from contact with chromated copper arsenat...

  13. Data Sources Available for Modeling Environmental Exposures in Older Adults

    EPA Science Inventory

    This report, “Data Sources Available for Modeling Environmental Exposures in Older Adults,” focuses on information sources and data available for modeling environmental exposures in the older U.S. population, defined here to be people 60 years and older, with an emphasis on those...

  14. Operation of the computer model for microenvironment solar exposure

    NASA Technical Reports Server (NTRS)

    Gillis, J. R.; Bourassa, R. J.; Gruenbaum, P. E.

    1995-01-01

    A computer model for microenvironmental solar exposure was developed to predict solar exposure to satellite surfaces which may shadow or reflect on one another. This document describes the technical features of the model as well as instructions for the installation and use of the program.

  15. MODELING MULTIPATHWAY EXPOSURES OF CHILDREN AND ADULTS TO PESTICIDES

    EPA Science Inventory

    A probabilistic model of individual exposure to chlorpyrifos has been developed in support of the United States Environmental Protection Agency (US EPA) National Human Exposure Assessment Survey (NHEXAS) and the Food Quality Protection Act (FQPA) program. The model examines a v...

  16. Assessment of relative potential for Legionella species or surrogates inhalation exposure from common water uses.

    PubMed

    Hines, Stephanie A; Chappie, Daniel J; Lordo, Robert A; Miller, Brian D; Janke, Robert J; Lindquist, H Alan; Fox, Kim R; Ernst, Hiba S; Taft, Sarah C

    2014-06-01

    The Legionella species have been identified as important waterborne pathogens in terms of disease morbidity and mortality. Microbial exposure assessment is a tool that can be utilized to assess the potential of Legionella species inhalation exposure from common water uses. The screening-level exposure assessment presented in this paper developed emission factors to model aerosolization, quantitatively assessed inhalation exposures of aerosolized Legionella species or Legionella species surrogates while evaluating two generalized levels of assumed water concentrations, and developed a relative ranking of six common in-home uses of water for potential Legionella species inhalation exposure. Considerable variability in the calculated exposure dose was identified between the six identified exposure pathways, with the doses differing by over five orders of magnitude in each of the evaluated exposure scenarios. The assessment of exposure pathways that have been epidemiologically associated with legionellosis transmission (ultrasonic and cool mist humidifiers) produced higher estimated inhalation exposure doses than pathways where epidemiological evidence of transmission has been less strong (faucet and shower) or absent (toilets and therapy pool). With consideration of the large uncertainties inherent in the exposure assessment process used, a relative ranking of exposure pathways from highest to lowest exposure doses was produced using culture-based measurement data and the assumption of constant water concentration across exposure pathways. In this ranking, the ultrasonic and cool mist humidifier exposure pathways were estimated to produce the highest exposure doses, followed by the shower and faucet exposure pathways, and then the toilet and therapy pool exposure pathways.

  17. Microwave detection of air showers with MIDAS

    NASA Astrophysics Data System (ADS)

    Facal San Luis, P.; Alekotte, I.; Alvarez, J.; Berlin, A.; Bertou, X.; Bogdan, M.; Bohacova, M.; Bonifazi, C.; Carvalho, W. R.; de Mello Neto, J. R. T.; Genat, J. F.; Mills, E.; Monasor, M.; Privitera, P.; Reyes, I. C.; Rouille D'Orfeuil, B.; Santos, E. M.; Wayne, S.; Williams, C.; Zas, E.

    2012-01-01

    MIDAS (MIcrowave Detector of Air Showers) is a prototype of a microwave telescope to detect extensive air showers: it images a 20°×10° region of the sky with a 4.5 m parabolic reflector and 53 feeds in the focal plane. It has been commissioned in March 2010 and is currently taking data. We present the design, performance and first results of MIDAS.

  18. Lateral distribution of electrons of air showers

    NASA Technical Reports Server (NTRS)

    Asakimori, K.; Maeda, T.; Kameda, T.; Mizushima, K.; Misaki, Y.

    1985-01-01

    The lateral distribution of electrons (LDE) of the air showers of size 10 to the 5th power to 10 to the 6th power was studied within one MU. It was found that the LDE of the air showers observed is well represented by NKG function except for vicinity of the core. It was also found that LDE measured by thin scintillators does not differ from that measured by thick ones of 50mm thickness.

  19. Structural peculiarities of the Quadrantid meteor shower

    NASA Technical Reports Server (NTRS)

    Isamutdinov, Sh. O.; Chebotarev, R. P.

    1987-01-01

    Systematic radio observations to investigate the Quadrantid meteor shower structure are regularly carried out. They have now been conducted annually in the period of its maximum activity, January 1 to 6, since 1966. The latest results of these investigations are presented, on the basis of 1981 to 1984 data obtained using new equipment with a limiting sensitivity of +7.7 sup m which make it possible to draw some conclusions on the Quadrantids shower structure both for transverse and lengthwise directions.

  20. Note on the 1972 Giacobinid meteor shower.

    NASA Technical Reports Server (NTRS)

    Harvey, G. A.

    1973-01-01

    It is shown that the 1972 Giacobinid meteor shower was extremely weak with a peak activity of two to three visual meteors per hour. Only two meteor spectra were obtained from the 17 slitless spectrograph systems operated by the Langley Research Center. The largely unexpected, essentially null results of the 1972 Giacobinid meteor shower observations are indicative of the present limited understanding and predictability of cosmic dust storms.

  1. Continuous monitoring of particle emissions during showering.

    PubMed

    Cowen, Kenneth A; Ollison, Will M

    2006-12-01

    Particle formation from showering may be attributed to dissolved mineral aerosols remaining after evaporation of micron-sized satellite droplets produced by the showerhead or from splashing of larger shower water droplets on surfaces. Duplicate continuous particle monitors measured particle size distributions in a ventilated residential bathroom under various showering conditions, using a full-size mannequin in the shower to simulate splashing effects during showering. Particle mass concentrations were estimated from measured shower particle number densities and used to develop emission factors for inhalable particles. Emission source strengths of 2.7-41.3 microg/ m3/min were estimated under the various test conditions using residential tap water in Columbus, OH. Calculated fine particulate matter (PM2.5) concentrations in the bathroom reached several hundred micrograms per cubic meter; calculated coarse particulate matter (PM10) levels approached 1000 microg/m3. Rates of particle formation tended to be highest for coarse shower spray settings with direct impact on the mannequin. No consistent effects of water temperature, water pressure, or spray setting on overall emission rates were apparent, although water temperature and spray setting did have an effect when varied within a single shower sampling run. Salt solutions were injected into the source water during some tests to assess the effects of total dissolved solids on particle emission rates. Injection of salts was shown to increase the PM2.5 particle formation rate by approximately one third, on average, for a doubling in tap water-dissolved solids content; PM10 source strengths approximately doubled under these conditions, because very few particles >10 microm were formed. PMID:17195485

  2. EFFECTS OF CORRELATED PROBABILISTIC EXPOSURE MODEL INPUTS ON SIMULATED RESULTS

    EPA Science Inventory

    In recent years, more probabilistic models have been developed to quantify aggregate human exposures to environmental pollutants. The impact of correlation among inputs in these models is an important issue, which has not been resolved. Obtaining correlated data and implementi...

  3. Advanced REACH Tool: a Bayesian model for occupational exposure assessment.

    PubMed

    McNally, Kevin; Warren, Nicholas; Fransman, Wouter; Entink, Rinke Klein; Schinkel, Jody; van Tongeren, Martie; Cherrie, John W; Kromhout, Hans; Schneider, Thomas; Tielemans, Erik

    2014-06-01

    This paper describes a Bayesian model for the assessment of inhalation exposures in an occupational setting; the methodology underpins a freely available web-based application for exposure assessment, the Advanced REACH Tool (ART). The ART is a higher tier exposure tool that combines disparate sources of information within a Bayesian statistical framework. The information is obtained from expert knowledge expressed in a calibrated mechanistic model of exposure assessment, data on inter- and intra-individual variability in exposures from the literature, and context-specific exposure measurements. The ART provides central estimates and credible intervals for different percentiles of the exposure distribution, for full-shift and long-term average exposures. The ART can produce exposure estimates in the absence of measurements, but the precision of the estimates improves as more data become available. The methodology presented in this paper is able to utilize partially analogous data, a novel approach designed to make efficient use of a sparsely populated measurement database although some additional research is still required before practical implementation. The methodology is demonstrated using two worked examples: an exposure to copper pyrithione in the spraying of antifouling paints and an exposure to ethyl acetate in shoe repair. PMID:24665110

  4. A statistical framework for the validation of a population exposure model based on personal exposure data

    NASA Astrophysics Data System (ADS)

    Rodriguez, Delphy; Valari, Myrto; Markakis, Konstantinos; Payan, Sébastien

    2016-04-01

    Currently, ambient pollutant concentrations at monitoring sites are routinely measured by local networks, such as AIRPARIF in Paris, France. Pollutant concentration fields are also simulated with regional-scale chemistry transport models such as CHIMERE (http://www.lmd.polytechnique.fr/chimere) under air-quality forecasting platforms (e.g. Prev'Air http://www.prevair.org) or research projects. These data may be combined with more or less sophisticated techniques to provide a fairly good representation of pollutant concentration spatial gradients over urban areas. Here we focus on human exposure to atmospheric contaminants. Based on census data on population dynamics and demographics, modeled outdoor concentrations and infiltration of outdoor air-pollution indoors we have developed a population exposure model for ozone and PM2.5. A critical challenge in the field of population exposure modeling is model validation since personal exposure data are expensive and therefore, rare. However, recent research has made low cost mobile sensors fairly common and therefore personal exposure data should become more and more accessible. In view of planned cohort field-campaigns where such data will be available over the Paris region, we propose in the present study a statistical framework that makes the comparison between modeled and measured exposures meaningful. Our ultimate goal is to evaluate the exposure model by comparing modeled exposures to monitor data. The scientific question we address here is how to downscale modeled data that are estimated on the county population scale at the individual scale which is appropriate to the available measurements. To assess this question we developed a Bayesian hierarchical framework that assimilates actual individual data into population statistics and updates the probability estimate.

  5. Frequency and intensity of comet showers from the Oort cloud

    SciTech Connect

    Heisler, J.; Alcock, C.; Tremaine, S.

    1987-05-01

    The nature of new comets and the frequency and intensity of comet showers are presently studied by means of a simulation in which an ensemble of one million comets is perturbed at random times by the Bahcall-Soneira (1980) Galaxy model's population of main sequence stars and white dwarfs. The time-integrated flux is dominated by the showers for comets whose semimajor axes are less than about 30,000 AU. The inclusion of tidal effects increases the loss rate of comets with semimajor axes between 10,000 and 20,000 AU by a factor of about 4, so that the Galactic tide, rather than individual stellar perturbations, is the dominant Oort cloud evolution-driving mechanism. 44 references.

  6. ASSESSING RESIDENTIAL EXPOSURE USING THE STOCHASTIC HUMAN EXPOSURE AND DOSE SIMULATION (SHEDS) MODEL

    EPA Science Inventory

    As part of a workshop sponsored by the Environmental Protection Agency's Office of Research and Development and Office of Pesticide Programs, the Aggregate Stochastic Human Exposure and Dose Simulation (SHEDS) Model was used to assess potential aggregate residential pesticide e...

  7. The average longitudinal air shower profile: exploring the shape information

    NASA Astrophysics Data System (ADS)

    Conceição, R.; Andringa, S.; Diogo, F.; Pimenta, M.

    2015-08-01

    The shape of the extensive air shower (EAS) longitudinal profile contains information about the nature of the primary cosmic ray. However, with the current detection capabilities, the assessment of this quantity in an event-by-event basis is still very challenging. In this work we show that the average longitudinal profile can be used to characterise the average behaviour of high energy cosmic rays. Using the concept of universal shower profile it is possible to describe the shape of the average profile in terms of two variables, which can be already measured by the current experiments. These variables present sensitivity to both average primary mass composition and to hadronic interaction properties in shower development. We demonstrate that the shape of the average muon production depth profile can be explored in the same way as the electromagnetic profile having a higher power of discrimination for the state of the art hadronic interaction models. The combination of the shape variables of both profiles provides a new powerful test to the existing hadronic interaction models, and may also provide important hints about multi-particle production at the highest energies.

  8. Modeling the interactions between noise exposure and other variables.

    PubMed

    Humes, L E; Jesteadt, W

    1991-07-01

    The interaction of noise exposure with other variables is reviewed. For the case of the interaction of noise with other variables that produce behavioral threshold shifts, the application of a newly developed model is described and demonstrated. This model, referred to as the modified power-law model, provides an accurate prediction of the combined effects of two threshold-elevating factors. The model accounts for the interaction of post-exposure a pre-existing pre-existing permanent loss or a pre-existing temporary loss. The model's application is demonstrated for multiple exposures to steady-state noise in which each exposure lasts as short as 12 min or as long as 6 h. Finally, implications of the model's application to the interaction long as 6 h. Finally, implications of the model's application to the interaction of noise with other ototraumatic agents are reviewed.

  9. A measurement of the muon number in showers using inclined events detected at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Rodriguez, G.

    2013-06-01

    The average muon content of measured showers with zenith angles between 62∘ and 80∘ detected at the Pierre Auger Observatory is obtained as a function of shower energy using a reconstruction method specifically designed for inclined showers and the hybrid character of the detector. The reconstruction of inclined showers relies on a comparison between the measured signals at ground and reference patterns at ground level from which an overall normalization factor is obtained. Since inclined showers are dominated by muons this factor gives the relative muon size. It can be calibrated using a subsample of showers simultaneously recorded with the fluorescence detector (FD) and the surface detector (SD) which provides an independent calorimetric measurement of the energy. The muon size obtained for each shower becomes a measurement of the relative number of muons with respect to the reference distributions. The precision of the measurement is assessed using simulated events which are reconstructed using exactly the same procedure. We compare the relative number of muons versus energy as obtained to simulations. Proton simulations with QGSJETII show a factor of 2.13 ± 0.04(stat) ± 0.11(sys) at 1019eV without significant variations in the energy range explored between 4 × 1018eV to 7 × 1019eV. We find that none of the current shower models, neither for proton nor for iron primaries, are able to predict as many muons as are observed.

  10. Radiation exposure modeling and project schedule visualization

    SciTech Connect

    Jaquish, W.R.; Enderlin, V.R.

    1995-10-01

    This paper discusses two applications using IGRIP (Interactive Graphical Robot Instruction Program) to assist environmental remediation efforts at the Department of Energy (DOE) Hanford Site. In the first application, IGRIP is used to calculate the estimated radiation exposure to workers conducting tasks in radiation environments. In the second, IGRIP is used as a configuration management tool to detect interferences between equipment and personnel work areas for multiple projects occurring simultaneously in one area. Both of these applications have the capability to reduce environmental remediation costs by reducing personnel radiation exposure and by providing a method to effectively manage multiple projects in a single facility.

  11. PBPK modeling of canine inhalation exposures to halogenated hydrocarbons.

    PubMed

    Vinegar, A

    2001-03-01

    Human exposure guidelines for halogenated hydrocarbons (halons) and halon replacement chemicals have been established using dose-response data obtained from canine cardiac sensitization studies. In order to provide a tool for decision makers and regulators tasked with setting guidelines for egress from exposure to halon replacement chemicals, a quantitative approach, using a physiologically based pharmacokinetic model, was established that allowed exposures to be assessed in terms of the chemical concentrations in blood during the exposure. This model, which includes a respiratory tract compartment containing a dead-space region, a pulmonary exchange area, and a breath-by-breath description of respiratory tract uptake, allows successful simulation of exhaled breath concentrations of humans during the first minute of exposure to the anesthetics halothane, isoflurane, and desflurane. In the current study, the human model was modified with canine parameters and validated with data obtained from dog studies with halothane, isoflurane, desflurane, and CFC-11. With consideration of appropriate values for ventilation and cardiac output, the model successfully simulated data collected under a variety of exposure scenarios. The canine model can be used for simulating blood concentrations associated with the potential for cardiac sensitization. These target blood concentrations can then be used with the human model for establishing safe human exposure duration. Development of the canine model stresses the need for appropriate data collection for model validation. PMID:11222869

  12. A numeric model to simulate solar individual ultraviolet exposure.

    PubMed

    Vernez, David; Milon, Antoine; Francioli, Laurent; Bulliard, Jean-Luc; Vuilleumier, Laurent; Moccozet, Laurent

    2011-01-01

    Exposure to solar ultraviolet (UV) light is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors. Individual exposure data remain scarce and development of alternative assessment methods is greatly needed. We developed a model simulating human exposure to solar UV. The model predicts the dose and distribution of UV exposure received on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a rendering engine that estimates the solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by each triangle was calculated, taking into account reflected, direct and diffuse radiation, and shading from other body parts. Dosimetric measurements (n = 54) were conducted in field conditions using a foam manikin as surrogate for an exposed individual. Dosimetric results were compared to the model predictions. The model predicted exposure to solar UV adequately. The symmetric mean absolute percentage error was 13%. Half of the predictions were within 17% range of the measurements. This model provides a tool to assess outdoor occupational and recreational UV exposures, without necessitating time-consuming individual dosimetry, with numerous potential uses in skin cancer prevention and research.

  13. The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial

    PubMed Central

    Sierevelt, Inger N.; van der Heijden, Bas C. J. M.; Dijkgraaf, Marcel G.; Frings-Dresen, Monique H. W.

    2016-01-01

    Purpose The aim of this study was to determine the cumulative effect of a routine (hot-to-) cold shower on sickness, quality of life and work productivity. Methods Between January and March 2015, 3018 participants between 18 and 65 years without severe comorbidity and no routine experience of cold showering were randomized (1:1:1:1) to a (hot-to-) cold shower for 30, 60, 90 seconds or a control group during 30 consecutive days followed by 60 days of showering cold at their own discretion for the intervention groups. The primary outcome was illness days and related sickness absence from work. Secondary outcomes were quality of life, work productivity, anxiety, thermal sensation and adverse reactions. Results 79% of participants in the interventions groups completed the 30 consecutive days protocol. A negative binomial regression model showed a 29% reduction in sickness absence for (hot-to-) cold shower regimen compared to the control group (incident rate ratio: 0.71, P = 0.003). For illness days there was no significant group effect. No related serious advents events were reported. Conclusion A routine (hot-to-) cold shower resulted in a statistical reduction of self-reported sickness absence but not illness days in adults without severe comorbidity. Trial Registration Netherlands National Trial Register NTR5183 PMID:27631616

  14. High sensitive X-ray films to detect electron showers in 100 GeV region

    NASA Technical Reports Server (NTRS)

    Taira, T.; Shirai, T.; Tateyama, N.; Torii, S.; Nishimura, J.; Fujii, M.; Yoshida, A.; Aizu, H.; Nomura, Y.; Kazuno, M.

    1985-01-01

    Nonscreen type X-ray films were used in emulsion chamber experiments to detect high energy showers in cosmic rays. Ranges of the detection threshold is from about 1 to 2 TeV depending on the exposure conditions. Different types of X-ray films and sheets i.e. high sensitive screen type X-ray films and luminescence sheets were tested. The threshold of the shower detection is found to be about 200 GeV, which is much lower than that of nonscreen type X-ray films. These films are useful to detect showers in the medium energy range, a few hundred GeV, of the cosmic ray electrons.

  15. Atmospheric trajectories and light curves of shower meteors

    NASA Astrophysics Data System (ADS)

    Koten, P.; Borovička, J.; Spurný, P.; Betlem, H.; Evans, S.

    2004-12-01

    Double station data on 496 meteors belonging to several meteor showers were obtained within the program of the video meteor observations during years 1998-2001. Analyzed meteors cover a range of photometric masses from 10-7 to 10-4 kg with a corresponding range of maximum brightness from +4.7 to -2.1 absolute magnitude. Atmospheric trajectories of Perseid, Orionid and Leonid meteors are analysed. These typical cometary high velocity meteors are compared to Geminid meteors with probable asteroidal origin and Taurid meteors - another cometary shower with significantly lower entry velocity. The light curves of the studied meteors vary widely, but generally are nearly symmetrical with the point of maximum brightness located close the to middle of the luminous trajectory. Small differences between showers are reported. We found that the height data are in good agreement with the dust-ball model predictions. The only difference is the beginning height behaviour. The beginning heights of cometary meteors increase with increasing photometric mass. These meteoroids probably contain a volatile part which starts to ablate before we are able to detect the meteors. The Geminid meteors are a different case. They start to ablate suddenly and their beginning height is almost constant in the whole range of studied meteoroid masses. In this case we observe real beginnings of meteor ablation.

  16. Analysis of Air Showers at the Trigger Threshold of KASCADE

    NASA Astrophysics Data System (ADS)

    Scholz, J.; Antoni, T.; Apel, W. D.; Bekk, K.; Bercuci, A.; Blümer, H.; Bozdog, H.; Brancus, I. M.; Büttner, C.; Chilingarian, A.; Daumiller, K.; Doll, P.; Engel, R.; Engler, J.; Feßler, F.; Gils, H. J.; Glasstetter, R.; Haungs, A.; Heck, D.; Hörandel, J. R.; Iwan, A.; Kampert, K-H.; Klages, H. O.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Müller, M.; Obenland, R.; Oehschläger, J.; Ostapchenko, S.; Petcu, M.; Rebel, H.; Risse, M.; Roth, M.; Schatz, G.; Schieler, H.; Thouw, T.; Ulrich, H.; van Buren, J.; Vardanyan, A.; Weindl, A.; Wochele, J.; Zabierowski, J.

    2003-07-01

    The KASCADE experiment measures extensive air showers. It is 100% efficient for showers which are induced by primary particles with energies above 1015 eV to pursue its main goal, the examination of the knee in the flux spectrum at ≈ 5 · 1015 eV. A specially adapted method to calculate two observables (Nch , the number of charged particles and Nµ , the number of muons) by means of a maximum likelihood estimate will be presented. The estimate combines different detector systems and works already at energies around the trigger threshold of KASCADE at ≈ 1014 eV. These observables are used to reconstruct a preliminary energy flux spectrum which is compared with direct measurements and previous measurements of KASCADE at energies above 1015 eV. The reconstruction of energy spectrum and elemental composition around the trigger threshold of KASCADE is important for two reasons. First the estimated spectrum at higher energies has to be congruent with the results of direct measurements. Second it is a cross-check of the interaction models underlying the analysis of extended air showers.

  17. Repeated Moderate Noise Exposure in the Rat--an Early Adulthood Noise Exposure Model.

    PubMed

    Mannström, Paula; Kirkegaard, Mette; Ulfendahl, Mats

    2015-12-01

    In this study, we investigated the effects of varying intensity levels of repeated moderate noise exposures on hearing. The aim was to define an appropriate intensity level that could be repeated several times without giving rise to a permanent hearing loss, and thus establish a model for early adulthood moderate noise exposure in rats. Female Sprague-Dawley rats were exposed to broadband noise for 90 min, with a 50 % duty cycle at levels of 101, 104, 107, or 110 dB sound pressure level (SPL), and compared to a control group of non-exposed animals. Exposure was repeated every 6 weeks for a maximum of six repetitions or until a permanent hearing loss was observed. Hearing was assessed by the auditory brainstem response (ABR). Rats exposed to the higher intensities of 107 and 110 dB SPL showed permanent threshold shifts following the first exposure, while rats exposed to 101 and 104 dB SPL could be exposed at least six times without a sustained change in hearing thresholds. ABR amplitudes decreased over time for all groups, including the non-exposed control group, while the latencies were unaffected. A possible change in noise susceptibility following the repeated moderate noise exposures was tested by subjecting the animals to high-intensity noise exposure of 110 dB for 4 h. Rats previously exposed repeatedly to 104 dB SPL were slightly more resistant to high-intensity noise exposure than non-exposed rats or rats exposed to 101 dB SPL. Repeated moderate exposure to 104 dB SPL broadband noise is a viable model for early adulthood noise exposure in rats and may be useful for the study of noise exposure on age-related hearing loss.

  18. MODELING AGGREGATE CHLORPYRIFOS EXPOSURE AND DOSE TO CHILDREN

    EPA Science Inventory

    To help address the aggregate exposure assessment needs of the Food Quality Protection Act, a physically-based probabilistic model (SHEDS-Pesticides, version 3) has been applied to estimate aggregate chlorpyrifos exposure and dose to children. Two age groups (0-4, 5-9 years) a...

  19. The primary composition beyond 10 to the 5th power GeV as deduced from high energy hadrons and muons in air showers

    NASA Technical Reports Server (NTRS)

    Grieder, P. K. F.

    1985-01-01

    Data obtained from a large set of air shower simulation calculations with use of highly refined hadronic interaction and shower simulation model are presented, in an attempt to solve the problem of primary chemical composition beyond 100,000 GeV total energy. It is rated that high energy hadrons in air showers offer a rather unique primary mass signature and show that the interpretation of high energy muon data is much more ambiguous. Predictions are compared with experimental data.

  20. Probability-summation model of multiple laser-exposure effects.

    PubMed

    Menendez, A R; Cheney, F E; Zuclich, J A; Crump, P

    1993-11-01

    A probability-summation model is introduced to provide quantitative criteria for discriminating independent from interactive effects of multiple laser exposures on biological tissue. Data that differ statistically from predictions of the probability-summation model indicate the action of sensitizing (synergistic/positive) or desensitizing (hardening/negative) biophysical interactions. Interactions are indicated when response probabilities vary with changes in the spatial or temporal separation of exposures. In the absence of interactions, probability-summation parsimoniously accounts for "cumulative" effects. Data analyzed using the probability-summation model show instances of both sensitization and desensitization of retinal tissue by laser exposures. Other results are shown to be consistent with probability-summation. The relevance of the probability-summation model to previous laser-bioeffects studies, models, and safety standards is discussed and an appeal is made for improved empirical estimates of response probabilities for single exposures.

  1. The efficacy of control measures for eradicating legionellae in showers.

    PubMed

    Makin, T; Hart, C A

    1990-07-01

    The efficacy of secondary control measures on showers colonized with legionellae was assessed. Hyperchlorination of shower heads and angle valve strainers had only a short-lived effect on legionellae. Automatic drain valves fitted to showers were ineffective in maintaining a reduction in the number of legionellae in shower water. Regular flushing of showers reduced legionellae to below detectable levels. Removal of dead-legs from the feed-pipes supplying hot water to showers, resulted in a decrease in legionellae in these sites but an increase in legionellae colonizing mixer valve components. PMID:1974902

  2. Comparison of modeling approaches to prioritize chemicals based on estimates of exposure and exposure potential

    PubMed Central

    Mitchell, Jade; Arnot, Jon A.; Jolliet, Olivier; Georgopoulos, Panos G.; Isukapalli, Sastry; Dasgupta, Surajit; Pandian, Muhilan; Wambaugh, John; Egeghy, Peter; Cohen Hubal, Elaine A.; Vallero, Daniel A.

    2014-01-01

    While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecological health outcomes. Recent improvements and advances such as high throughput data gathering, high performance computational capabilities, and predictive chemical inherency methodology make this an opportune time to develop an exposure-based prioritization approach that can systematically utilize and link the asymmetrical bodies of knowledge for hazard and exposure. In response to the US EPA’s need to develop novel approaches and tools for rapidly prioritizing chemicals, a “Challenge” was issued to several exposure model developers to aid the understanding of current systems in a broader sense and to assist the US EPA’s effort to develop an approach comparable to other international efforts. A common set of chemicals were prioritized under each current approach. The results are presented herein along with a comparative analysis of the rankings of the chemicals based on metrics of exposure potential or actual exposure estimates. The analysis illustrates the similarities and differences across the domains of information incorporated in each modeling approach. The overall findings indicate a need to reconcile exposures from diffuse, indirect sources (far-field) with exposures from directly, applied chemicals in consumer products or resulting from the presence of a chemical in a microenvironment like a home or vehicle. Additionally, the exposure scenario, including the mode of entry into the environment (i.e. through air, water or sediment) appears to be an important determinant of the level of agreement between modeling approaches. PMID:23707726

  3. Modeling population exposures to outdoor sources of hazardous air pollutants.

    PubMed

    Ozkaynak, Halûk; Palma, Ted; Touma, Jawad S; Thurman, James

    2008-01-01

    Accurate assessment of human exposures is an important part of environmental health effects research. However, most air pollution epidemiology studies rely upon imperfect surrogates of personal exposures, such as information based on available central-site outdoor concentration monitoring or modeling data. In this paper, we examine the limitations of using outdoor concentration predictions instead of modeled personal exposures for over 30 gaseous and particulate hazardous air pollutants (HAPs) in the US. The analysis uses the results from an air quality dispersion model (the ASPEN or Assessment System for Population Exposure Nationwide model) and an inhalation exposure model (the HAPEM or Hazardous Air Pollutant Exposure Model, Version 5), applied by the US. Environmental protection Agency during the 1999 National Air Toxic Assessment (NATA) in the US. Our results show that the total predicted chronic exposure concentrations of outdoor HAPs from all sources are lower than the modeled ambient concentrations by about 20% on average for most gaseous HAPs and by about 60% on average for most particulate HAPs (mainly, due to the exclusion of indoor sources from our modeling analysis and lower infiltration of particles indoors). On the other hand, the HAPEM/ASPEN concentration ratio averages for onroad mobile source exposures were found to be greater than 1 (around 1.20) for most mobile-source related HAPs (e.g. 1, 3-butadiene, acetaldehyde, benzene, formaldehyde) reflecting the importance of near-roadway and commuting environments on personal exposures to HAPs. The distribution of the ratios of personal to ambient concentrations was found to be skewed for a number of the VOCs and reactive HAPs associated with major source emissions, indicating the importance of personal mobility factors. We conclude that the increase in personal exposures from the corresponding predicted ambient levels tends to occur near locations where there are either major emission sources of HAPs

  4. Exposure assessment for trihalomethanes in municipal drinking water and risk reduction strategy.

    PubMed

    Chowdhury, Shakhawat

    2013-10-01

    Lifetime exposure to disinfection byproducts (DBPs) in municipal water may pose risks to human health. Current approaches of exposure assessments use DBPs in cold water during showering, while warming of chlorinated water during showering may increase trihalomethane (THM) formation in the presence of free residual chlorine. Further, DBP exposure through dermal contact during showering is estimated using steady-state condition between the DBPs in shower water impacting on human skin and skin exposed to shower water. The lag times to achieve steady-state condition between DBPs in shower water and human skin can vary in the range of 9.8-391.2 min, while shower duration is often less than the lag times. Assessment of exposure without incorporating these factors might have misinterpreted DBP exposure in some previous studies. In this study, exposure to THMs through ingestion was estimated using cold water THMs, while THM exposure through inhalation and dermal contact during showering was estimated using THMs in warm water. Inhalation of THMs was estimated using THM partition into the shower air, while dermal uptake was estimated by incorporating lag times (e.g., unsteady and steady-state phases of exposure) during showering. Probabilistic approach was followed to incorporate uncertainty in the assessment. Inhalation and dermal contact during showering contributed 25-60% of total exposure. Exposure to THMs during showering can be controlled by varying shower stall volume, shower duration and air exchange rate following power law equations. The findings might be useful in understanding exposure to THMs, which can be extended to other volatile compounds in municipal water.

  5. Development of a standard documentation protocol for communicating exposure models.

    PubMed

    Ciffroy, P; Altenpohl, A; Fait, G; Fransman, W; Paini, A; Radovnikovic, A; Simon-Cornu, M; Suciu, N; Verdonck, F

    2016-10-15

    An important step in building a computational model is its documentation; a comprehensive and structured documentation can improve the model applicability and transparency in science/research and for regulatory purposes. This is particularly crucial and challenging for environmental and/or human exposure models that aim to establish quantitative relationships between personal exposure levels and their determinants. Exposure models simulate the transport and fate of a contaminant from the source to the receptor and may involve a large set of entities (e.g. all the media the contaminants may pass though). Such complex models are difficult to be described in a comprehensive, unambiguous and accessible way. Bad communication of assumptions, theory, structure and/or parameterization can lead to lack of confidence by the user and it may be source of errors. The goal of this paper is to propose a standard documentation protocol (SDP) for exposure models, i.e. a generic format and a standard structure by which all exposure models could be documented. For this purpose, a CEN (European Committee for Standardisation) workshop was set up with objective to agree on minimum requirements for the amount and type of information to be provided on exposure models documentation along with guidelines for the structure and presentation of the information. The resulting CEN workshop agreement (CWA) was expected to facilitate a more rigorous formulation of exposure models description and the understanding by users. This paper intends to describe the process followed for defining the SDP, the standardisation approach, as well as the main components of the SDP resulting from a wide consultation of interested stakeholders. The main outcome is a CEN CWA which establishes terms and definitions for exposure models and their elements, specifies minimum requirements for the amount and type of information to be documented, and proposes a structure for communicating the documentation to different

  6. Reconstructing exposures from biomarkers using exposure-pharmacokinetic modeling--A case study with carbaryl.

    PubMed

    Brown, Kathleen; Phillips, Martin; Grulke, Christopher; Yoon, Miyoung; Young, Bruce; McDougall, Robin; Leonard, Jeremy; Lu, Jingtao; Lefew, William; Tan, Yu-Mei

    2015-12-01

    Sources of uncertainty involved in exposure reconstruction for short half-life chemicals were characterized using computational models that link external exposures to biomarkers. Using carbaryl as an example, an exposure model, the Cumulative and Aggregate Risk Evaluation System (CARES), was used to generate time-concentration profiles for 500 virtual individuals exposed to carbaryl. These exposure profiles were used as inputs into a physiologically based pharmacokinetic (PBPK) model to predict urinary biomarker concentrations. These matching dietary intake levels and biomarker concentrations were used to (1) compare three reverse dosimetry approaches based on their ability to predict the central tendency of the intake dose distribution; and (2) identify parameters necessary for a more accurate exposure reconstruction. This study illustrates the trade-offs between using non-iterative reverse dosimetry methods that are fast, less precise and iterative methods that are slow, more precise. This study also intimates the necessity of including urine flow rate and elapsed time between last dose and urine sampling as part of the biomarker sampling collection for better interpretation of urinary biomarker data of short biological half-life chemicals. Resolution of these critical data gaps can allow exposure reconstruction methods to better predict population-level intake doses from large biomonitoring studies.

  7. Comprehensive European dietary exposure model (CEDEM) for food additives.

    PubMed

    Tennant, David R

    2016-05-01

    European methods for assessing dietary exposures to nutrients, additives and other substances in food are limited by the availability of detailed food consumption data for all member states. A proposed comprehensive European dietary exposure model (CEDEM) applies summary data published by the European Food Safety Authority (EFSA) in a deterministic model based on an algorithm from the EFSA intake method for food additives. The proposed approach can predict estimates of food additive exposure provided in previous EFSA scientific opinions that were based on the full European food consumption database.

  8. Modeling of exposure to carbon monoxide in fires

    SciTech Connect

    Cagliostro, D.E.

    1980-11-01

    A mathematical model is developed to predict carboxyhemoglobin concentrations in regions of the body for short exposures to carbon monoxide levels expected during escape from aircraft fires. The model includes the respiratory and circulatory dynamics of absorption and distribution of carbon monoxide and carboxyhemoglobin. Predictions of carboxyhemoglobin concentrations are compared to experimental values obtained for human exposures to constant high carbon monoxide levels. Predictions are within 20% of experimental values. For short exposure times, transient concentration effects are predicted. The effect of stress is studied and found to increase carboxyhemoglobin levels substantially compared to a rest state.

  9. Comparing the ecological relevance of four wave exposure models

    NASA Astrophysics Data System (ADS)

    Sundblad, G.; Bekkby, T.; Isæus, M.; Nikolopoulos, A.; Norderhaug, K. M.; Rinde, E.

    2014-03-01

    Wave exposure is one of the main structuring forces in the marine environment. Methods that enable large scale quantification of environmental variables have become increasingly important for predicting marine communities in the context of spatial planning and coastal zone management. Existing methods range from cartographic solutions to numerical hydrodynamic simulations, and differ in the scale and spatial coverage of their outputs. Using a biological exposure index we compared the performance of four wave exposure models ranging from simple to more advanced techniques. All models were found to be related to the biological exposure index and their performance, measured as bootstrapped R2 distributions, overlapped. Qualitatively, there were differences in the spatial patterns indicating higher complexity with more advanced techniques. In order to create complex spatial patterns wave exposure models should include diffraction, especially in coastal areas rich in islands. The inclusion of wind strength and frequency, in addition to wind direction and bathymetry, further tended to increase the amount of explained variation. The large potential of high-resolution numerical models to explain the observed patterns of species distribution in complex coastal areas provide exciting opportunities for future research. Easy access to relevant wave exposure models will aid large scale habitat classification systems and the continuously growing field of marine species distribution modelling, ultimately serving marine spatial management and planning.

  10. A review and evaluation of intraurban air pollution exposure models.

    PubMed

    Jerrett, Michael; Arain, Altaf; Kanaroglou, Pavlos; Beckerman, Bernardo; Potoglou, Dimitri; Sahsuvaroglu, Talar; Morrison, Jason; Giovis, Chris

    2005-03-01

    The development of models to assess air pollution exposures within cities for assignment to subjects in health studies has been identified as a priority area for future research. This paper reviews models for assessing intraurban exposure under six classes, including: (i) proximity-based assessments, (ii) statistical interpolation, (iii) land use regression models, (iv) line dispersion models, (v) integrated emission-meteorological models, and (vi) hybrid models combining personal or household exposure monitoring with one of the preceding methods. We enrich this review of the modelling procedures and results with applied examples from Hamilton, Canada. In addition, we qualitatively evaluate the models based on key criteria important to health effects assessment research. Hybrid models appear well suited to overcoming the problem of achieving population representative samples while understanding the role of exposure variation at the individual level. Remote sensing and activity-space analysis will complement refinements in pre-existing methods, and with expected advances, the field of exposure assessment may help to reduce scientific uncertainties that now impede policy intervention aimed at protecting public health.

  11. Modeling Exposure to Persistent Chemicals in Hazard and Risk Assessment

    SciTech Connect

    Cowan-Ellsberry, Christina E.; McLachlan, Michael S.; Arnot, Jon A.; MacLeod, Matthew; McKone, Thomas E.; Wania, Frank

    2008-11-01

    Fate and exposure modeling has not thus far been explicitly used in the risk profile documents prepared to evaluate significant adverse effect of candidate chemicals for either the Stockholm Convention or the Convention on Long-Range Transboundary Air Pollution. However, we believe models have considerable potential to improve the risk profiles. Fate and exposure models are already used routinely in other similar regulatory applications to inform decisions, and they have been instrumental in building our current understanding of the fate of POP and PBT chemicals in the environment. The goal of this paper is to motivate the use of fate and exposure models in preparing risk profiles in the POP assessment procedure by providing strategies for incorporating and using models. The ways that fate and exposure models can be used to improve and inform the development of risk profiles include: (1) Benchmarking the ratio of exposure and emissions of candidate chemicals to the same ratio for known POPs, thereby opening the possibility of combining this ratio with the relative emissions and relative toxicity to arrive at a measure of relative risk. (2) Directly estimating the exposure of the environment, biota and humans to provide information to complement measurements, or where measurements are not available or are limited. (3) To identify the key processes and chemical and/or environmental parameters that determine the exposure; thereby allowing the effective prioritization of research or measurements to improve the risk profile. (4) Predicting future time trends including how quickly exposure levels in remote areas would respond to reductions in emissions. Currently there is no standardized consensus model for use in the risk profile context. Therefore, to choose the appropriate model the risk profile developer must evaluate how appropriate an existing model is for a specific setting and whether the assumptions and input data are relevant in the context of the application

  12. Assessing total exposures to gasoline vapor using the source exposure model.

    PubMed

    Edgerton, S A; Shah, J J

    1992-01-01

    Recent developments in source apportionment modeling of volatile organic compounds (VOCs) include receptor modeling (RM) applications to "total" (indoor and outdoor) exposure assessment for source of VOC. Source fingerprints are available for major VOC sources such as gasoline vapor, automobile exhaust, refinery emissions, cleaning solvent vapors, printing inks, and waste-water treatment facilities. The relative proportion of each VOC species in the source fingerprint enables the RM method, through a least squares analysis, to identify each source's presence and quantify its contribution to ambient air concentrations. Sampling periods and locations may be selected to represent microenvironmental exposures. Receptor modeling has direct applicability to determining the relative contribution of gasoline vapors to VOC exposures in the general population.

  13. Assessing total exposures to gasoline vapor using the source exposure model.

    PubMed

    Edgerton, S A; Shah, J J

    1992-01-01

    Recent developments in source apportionment modeling of volatile organic compounds (VOCs) include receptor modeling (RM) applications to "total" (indoor and outdoor) exposure assessment for source of VOC. Source fingerprints are available for major VOC sources such as gasoline vapor, automobile exhaust, refinery emissions, cleaning solvent vapors, printing inks, and waste-water treatment facilities. The relative proportion of each VOC species in the source fingerprint enables the RM method, through a least squares analysis, to identify each source's presence and quantify its contribution to ambient air concentrations. Sampling periods and locations may be selected to represent microenvironmental exposures. Receptor modeling has direct applicability to determining the relative contribution of gasoline vapors to VOC exposures in the general population. PMID:1504631

  14. The modified model of radiation risk at radon exposure.

    PubMed

    Zhukovsky, Michael; Demin, Vladimir; Yarmoshenko, Ilia

    2014-07-01

    The combined modified model of risk assessment from an indoor radon exposure is proposed. Multiplicative dependence on fatal lung cancer is used. The model has been developed on the basis of the modern health risk theory and the results of epidemiological studies with the special attention to the results of the European combined study and the WISMUT miners cohort study. The model is presented as an age-specific relative risk coefficient for a single (short-term) exposure. The risk coefficient for an extended exposure can be obtained from this risk coefficient in the accordance with the risk theory. The smoothed dependences of the risk coefficients on time since exposure and attained age and radon progeny concentration are suggested.

  15. Portable Water-Saving Shower For Emergencies

    NASA Technical Reports Server (NTRS)

    Grenier, Francis E.

    1991-01-01

    Stowable compact unit sprays from many directions. Proposed portable emergency fogging shower rinses harmful chemicals from person. Includes double-walled transparent, approximately cylindrical curtain containing sets of interior nozzles on regularly spaced loops. Sealed at top and bottom. Victim of contamination enters through longitudinal zippered opening. Pressurized mixture of air and water flows through selected nozzles, creating foglike spray scrubbing contaminants from skin and clothing. Intended for use on Space Station, also used in laboratories and factories on Earth, or for routine shower bathing in areas with limited water supplies.

  16. Personal Exposure to Mixtures of Volatile Organic Compounds: Modeling and Further Analysis of the RIOPA Data

    PubMed Central

    Batterman, Stuart; Su, Feng-Chiao; Li, Shi; Mukherjee, Bhramar; Jia, Chunrong

    2015-01-01

    INTRODUCTION Emission sources of volatile organic compounds (VOCs) are numerous and widespread in both indoor and outdoor environments. Concentrations of VOCs indoors typically exceed outdoor levels, and most people spend nearly 90% of their time indoors. Thus, indoor sources generally contribute the majority of VOC exposures for most people. VOC exposure has been associated with a wide range of acute and chronic health effects; for example, asthma, respiratory diseases, liver and kidney dysfunction, neurologic impairment, and cancer. Although exposures to most VOCs for most persons fall below health-based guidelines, and long-term trends show decreases in ambient emissions and concentrations, a subset of individuals experience much higher exposures that exceed guidelines. Thus, exposure to VOCs remains an important environmental health concern. The present understanding of VOC exposures is incomplete. With the exception of a few compounds, concentration and especially exposure data are limited; and like other environmental data, VOC exposure data can show multiple modes, low and high extreme values, and sometimes a large portion of data below method detection limits (MDLs). Field data also show considerable spatial or interpersonal variability, and although evidence is limited, temporal variability seems high. These characteristics can complicate modeling and other analyses aimed at risk assessment, policy actions, and exposure management. In addition to these analytic and statistical issues, exposure typically occurs as a mixture, and mixture components may interact or jointly contribute to adverse effects. However most pollutant regulations, guidelines, and studies remain focused on single compounds, and thus may underestimate cumulative exposures and risks arising from coexposures. In addition, the composition of VOC mixtures has not been thoroughly investigated, and mixture components show varying and complex dependencies. Finally, although many factors are

  17. Modelling survival: exposure pattern, species sensitivity and uncertainty.

    PubMed

    Ashauer, Roman; Albert, Carlo; Augustine, Starrlight; Cedergreen, Nina; Charles, Sandrine; Ducrot, Virginie; Focks, Andreas; Gabsi, Faten; Gergs, André; Goussen, Benoit; Jager, Tjalling; Kramer, Nynke I; Nyman, Anna-Maija; Poulsen, Veronique; Reichenberger, Stefan; Schäfer, Ralf B; Van den Brink, Paul J; Veltman, Karin; Vogel, Sören; Zimmer, Elke I; Preuss, Thomas G

    2016-01-01

    The General Unified Threshold model for Survival (GUTS) integrates previously published toxicokinetic-toxicodynamic models and estimates survival with explicitly defined assumptions. Importantly, GUTS accounts for time-variable exposure to the stressor. We performed three studies to test the ability of GUTS to predict survival of aquatic organisms across different pesticide exposure patterns, time scales and species. Firstly, using synthetic data, we identified experimental data requirements which allow for the estimation of all parameters of the GUTS proper model. Secondly, we assessed how well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates to build species sensitivity distributions for different exposure patterns. We find that GUTS adequately predicts survival across exposure patterns that vary over time. When toxicity is assessed for time-variable concentrations species may differ in their responses depending on the exposure profile. This can result in different species sensitivity rankings and safe levels. The interplay of exposure pattern and species sensitivity deserves systematic investigation in order to better understand how organisms respond to stress, including humans. PMID:27381500

  18. Modelling survival: exposure pattern, species sensitivity and uncertainty

    NASA Astrophysics Data System (ADS)

    Ashauer, Roman; Albert, Carlo; Augustine, Starrlight; Cedergreen, Nina; Charles, Sandrine; Ducrot, Virginie; Focks, Andreas; Gabsi, Faten; Gergs, André; Goussen, Benoit; Jager, Tjalling; Kramer, Nynke I.; Nyman, Anna-Maija; Poulsen, Veronique; Reichenberger, Stefan; Schäfer, Ralf B.; van den Brink, Paul J.; Veltman, Karin; Vogel, Sören; Zimmer, Elke I.; Preuss, Thomas G.

    2016-07-01

    The General Unified Threshold model for Survival (GUTS) integrates previously published toxicokinetic-toxicodynamic models and estimates survival with explicitly defined assumptions. Importantly, GUTS accounts for time-variable exposure to the stressor. We performed three studies to test the ability of GUTS to predict survival of aquatic organisms across different pesticide exposure patterns, time scales and species. Firstly, using synthetic data, we identified experimental data requirements which allow for the estimation of all parameters of the GUTS proper model. Secondly, we assessed how well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates to build species sensitivity distributions for different exposure patterns. We find that GUTS adequately predicts survival across exposure patterns that vary over time. When toxicity is assessed for time-variable concentrations species may differ in their responses depending on the exposure profile. This can result in different species sensitivity rankings and safe levels. The interplay of exposure pattern and species sensitivity deserves systematic investigation in order to better understand how organisms respond to stress, including humans.

  19. Modelling survival: exposure pattern, species sensitivity and uncertainty

    PubMed Central

    Ashauer, Roman; Albert, Carlo; Augustine, Starrlight; Cedergreen, Nina; Charles, Sandrine; Ducrot, Virginie; Focks, Andreas; Gabsi, Faten; Gergs, André; Goussen, Benoit; Jager, Tjalling; Kramer, Nynke I.; Nyman, Anna-Maija; Poulsen, Veronique; Reichenberger, Stefan; Schäfer, Ralf B.; Van den Brink, Paul J.; Veltman, Karin; Vogel, Sören; Zimmer, Elke I.; Preuss, Thomas G.

    2016-01-01

    The General Unified Threshold model for Survival (GUTS) integrates previously published toxicokinetic-toxicodynamic models and estimates survival with explicitly defined assumptions. Importantly, GUTS accounts for time-variable exposure to the stressor. We performed three studies to test the ability of GUTS to predict survival of aquatic organisms across different pesticide exposure patterns, time scales and species. Firstly, using synthetic data, we identified experimental data requirements which allow for the estimation of all parameters of the GUTS proper model. Secondly, we assessed how well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates to build species sensitivity distributions for different exposure patterns. We find that GUTS adequately predicts survival across exposure patterns that vary over time. When toxicity is assessed for time-variable concentrations species may differ in their responses depending on the exposure profile. This can result in different species sensitivity rankings and safe levels. The interplay of exposure pattern and species sensitivity deserves systematic investigation in order to better understand how organisms respond to stress, including humans. PMID:27381500

  20. Muons in Air Showers at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Unger, M.

    We present measurements of muons in air showers at ultra-high energies with the Pierre Auger Observatory. The number of muons at the ground in air showers detected at large zenith angles is determined as a function of energy and the results are compared to air shower simulations. Furthermore, using data collected at zenith angles smaller than 60°, rescaling factors are derived that quantify the deficit of muon production in air shower simulations.

  1. Noise exposure levels from model airplane engines.

    PubMed

    Pearlman, R C; Miller, M

    1985-01-01

    Previous research indicates that noise levels from unmuffled model airplane engines produce sufficient noise to cause TTS. The present study explored SPLs of smaller engines under 3.25 cc (.19 cu. in.) and the effectiveness of engine mufflers. Results showed that model airplanes can exceed a widely used damage risk criterion (DRC) but that engine mufflers can reduce levels below DRC. Handling model gasoline engines should be added to the list of recreational activities such as snow-mobile and motorcycle riding, shooting, etc. in which the participant's hearing may be in jeopardy. Suggestions are presented to the model engine enthusiast for avoiding damage to hearing.

  2. Underwater Sound Propagation Modeling Methods for Predicting Marine Animal Exposure.

    PubMed

    Hamm, Craig A; McCammon, Diana F; Taillefer, Martin L

    2016-01-01

    The offshore exploration and production (E&P) industry requires comprehensive and accurate ocean acoustic models for determining the exposure of marine life to the high levels of sound used in seismic surveys and other E&P activities. This paper reviews the types of acoustic models most useful for predicting the propagation of undersea noise sources and describes current exposure models. The severe problems caused by model sensitivity to the uncertainty in the environment are highlighted to support the conclusion that it is vital that risk assessments include transmission loss estimates with statistical measures of confidence.

  3. Underwater Sound Propagation Modeling Methods for Predicting Marine Animal Exposure.

    PubMed

    Hamm, Craig A; McCammon, Diana F; Taillefer, Martin L

    2016-01-01

    The offshore exploration and production (E&P) industry requires comprehensive and accurate ocean acoustic models for determining the exposure of marine life to the high levels of sound used in seismic surveys and other E&P activities. This paper reviews the types of acoustic models most useful for predicting the propagation of undersea noise sources and describes current exposure models. The severe problems caused by model sensitivity to the uncertainty in the environment are highlighted to support the conclusion that it is vital that risk assessments include transmission loss estimates with statistical measures of confidence. PMID:26610982

  4. Simplified pregnant woman models for the fetus exposure assessment

    NASA Astrophysics Data System (ADS)

    Jala, Marjorie; Conil, Emmanuelle; Varsier, Nadège; Wiart, Joe; Hadjem, Abdelhamid; Moulines, Éric; Lévy-Leduc, Céline

    2013-05-01

    In this paper, we introduce a study that we carried out in order to validate the use of a simplified pregnant woman model for the assessment of the fetus exposure to radio frequency waves. This simplified model, based on the use of a homogeneous tissue to replace most of the inner organs of the virtual mother, would allow us to deal with many issues that are raised because of the lack of pregnant woman models for numerical dosimetry. Using specific absorption rate comparisons, we show that this model could be used to estimate the fetus exposure to plane waves.

  5. USE OF PHARMACOKINETIC MODELING TO DESIGN STUDIES FOR PATHWAY-SPECIFIC EXPOSURE MODEL EVALUATION

    EPA Science Inventory

    Validating an exposure pathway model is difficult because the biomarker, which is often used to evaluate the model prediction, is an integrated measure for exposures from all the exposure routes/pathways. The purpose of this paper is to demonstrate a method to use pharmacokeneti...

  6. EXPOSURE RELATED DOSE ESTIMATING MODEL (ERDEM)

    EPA Science Inventory

    ERDEM is a physiologically-based pharmacokinetic (PBPK) model with a graphical user interface (GUI) front end. Such a mathematical model was needed to make reliable estimates of the chemical dose to organs of animals or humans because of uncertainties of making route-to route, lo...

  7. Correlation of angular and lateral distributions of electrons in extensive air showers

    NASA Astrophysics Data System (ADS)

    Giller, Maria; Śmiałkowski, Andrzej; Legumina, Remigiusz

    2016-08-01

    The aim of this paper is to explain the weak correlation of the angular and lateral deflections of electrons in extensive air showers in the primary energy range 1016-1019 eV, when compared with that in some models of electron propagation. We derive analytical formulae for the correlation coefficient in the multiple scattering model with energy losses and show a strong role of the ionisation in diminishing the correlation. By considering a Heitler-like model of an electromagnetic cascade we show also that the presence of photons, parent to electrons, causes a decrease of the correlation, roughly explaining quantitatively the small correlation in air showers.

  8. Inhalational model of cocaine exposure in mice: neuroteratological effects.

    PubMed

    He, Fang; Lidow, Irina A; Lidow, Michael S

    2006-01-01

    We developed a novel inhalation-based mouse model of prenatal cocaine exposure. This model approximates cocaine abuse via smoking, the preferred route of cocaine administration by heavy drug users. The model is also characterized by (i) absence of procedural stress from drug administration, (ii) long-term drug exposure starting weeks before pregnancy and continuing throughout the entire gestation, and (iii) self-administration of cocaine in multi-hour daily sessions reminiscent of drug binges, which allows animals to set up the levels of their own drug consumption. The offspring of female mice inhaling cocaine in our model displayed no gross alterations in their cortical cytoarchitecture. These offspring, however, showed significant impairments in sustained attention and spatial working memory. We hope that the introduction of the present model will lead to a significant increase in our understanding of outcomes of prenatal cocaine exposure. PMID:16414242

  9. Assessing risk from dangerous meteoroids in main meteor showers

    NASA Astrophysics Data System (ADS)

    Murtazov, A.

    2015-01-01

    The risk from dangerous meteoroids in main meteor showers is calculated. The showers were: Quadrantids-2014; Eta Aquariids-2013, Perseids-2014 and Geminids-2014. The computed results for the risks during the shower periods of activity and near the maximum are provided.

  10. Modeling tribal exposures to methyl mercury from fish consumption.

    PubMed

    Xue, Jianping; Zartarian, Valerie; Mintz, Bruce; Weber, Marc; Bailey, Ken; Geller, Andrew

    2015-11-15

    Exposure assessment and risk management considerations for tribal fish consumption are different than for the general U.S. population because of higher fish intake from subsistence fishing and/or from unique cultural practices. This research summarizes analyses of available data and methodologies for estimating tribal fish consumption exposures to methyl mercury (MeHg). Large MeHg fish tissue data sets from the Environmental Protections Agency's (EPA's) Office of Water, USGS's EMMMA program, and other data sources, were integrated, analyzed, and combined with fish intake (consumption) data for exposure analyses using EPA's SHEDS-Dietary model. Results were mapped with GIS tools to depict spatial distributions of the MeHg in fish tissues and fish consumption exposure patterns. Contribution analyses indicates the major sources for those exposures, such as type and length of fish, geographical distribution (water bodies), and dietary exposure patterns. Sensitivity analyses identify the key variables and exposure pathways. Our results show that MeHg exposure of tribal populations from fish are about 3 to 10 times higher than the US general population and that exposure poses potential health risks. The estimated risks would be reduced as much as 50%, especially for high percentiles, just by avoiding consumption of fish species with higher MeHg concentrations such as walleye and bowfin, even without changing total fish intake. These exposure assessment methods and tools can help inform decisions regarding meal sizes and frequency, types of fish and water bodies to avoid, and other factors to minimize exposures and potential health risks from contaminated fish on tribal lands. PMID:26151654

  11. The meteor-shower complex of comet C/1917 F1 (Mellish)

    NASA Astrophysics Data System (ADS)

    Neslušan, L.; Hajduková, M.

    2014-06-01

    Aims: In our overall work, we attempt to predict some new meteor showers associated with as many as possible known periodic comets and to find the generic relationship of some already known showers with these comets. In this paper, we focus our attention on the meteor-shower complex of the long-period comet C/1917 F1 (Mellish), which is the known parent body of the December Monocerotids. Some other showers have also been suggested to be associated with this comet. We map its whole complex here. Methods: For five perihelion passages of the parent comet in the past, we model associated theoretical streams, with each consisting of 10 000 test particles and follow their dynamical evolution until the present. Subsequently, we analyze the orbital characteristics of the parts of found streams that approach the Earth's orbit. Results: We confirm the generic relationship between the studied parent comet and December Monocerotids. The comet is probably also the parent body of the April ρ-Cygnids. The evolution of meteoroids to the orbits of April ρ-Cygnids is very long at about 20 millennia. If we follow even a longer evolutionary period, which is up to 50 millennia, then two diffuse showers with the radiant situated symmetrically to both the December Monocerotids and April ρ-Cygnids showers with respect to the apex of the Earth's motion occur. Our simulation does not confirm any relationship between C/1917 F1 and the November Orionids, although this shower was found in all three databases of observed orbits.

  12. A critical analysis of air shower structure functions and size spectrum measurements with the NBU air shower array

    NASA Technical Reports Server (NTRS)

    Chaudhuri, N.; Basak, D. K.

    1985-01-01

    A total of 11,000 showers in the size range 10 to the 4 to 10 to the 6 particles so far detected by the NBU air shower array has been analyzed using five different structure functions. A comparison of structure functions in terms: (1) of shower size; and (2) electron density at various core distances has been discussed to indicate the present status of structure functions in air shower analysis.

  13. The new July meteor shower

    NASA Astrophysics Data System (ADS)

    Zoladek, Przemyslaw; Wisniewski, Mariusz

    2012-12-01

    A new meteor stream was found after an activity outburst observed on 2005 July 15. The radiant was located five degrees west of the possible early Perseid radiant, close to the star Zeta Cassiopeiae. Numerous bright meteors and fireballs were observed during this maximum. Analysis of the IMO Video Database and the SonotaCo orbital database revealed an annual stream which is active just before the appearance of the first Perseids, with a clearly visible maximum at solar longitude 113°1. Activity of the stream was estimated as two times higher than activity of the Alpha Capricornids at the same time. The activity period extends from July 12 to 17, during maximum the radiant is visible at coordinates alpha = 5°9, delta = +50°5, and observed meteors are fast, with Vg = 57.4 km/s. The shower was reported to the IAU Meteor Data Center and recognized as a new discovery. According to IAU nomenclature the new stream should be named the Zeta Cassiopeiids (ZCS). %z Arlt R. (1992). WGN, Journal of the IMO, 20:2, 62-69. Drummond J. D. (1981). Icarus, 45, 545-553. Kiraga M. and Olech A. (2001). In Arlt R., Triglav M., and Trayner C., editors, Proceedings of the International Meteor Conference, Pucioasa, Romania, 21-24 September 2000, pages 45-51. IMO. Molau S. (2007). In Bettonvil F. and Kac J., editors, Proceedings of the International Meteor Conference, Roden, The Netherlands, 14-17 September 2006, pages 38-55. IMO. Molau S. and Rendtel J. (2009). WGN, Journal of the IMO, 37:4, 98-121. Olech A., Zoladek P., Wisniewski M., Krasnowski M., Kwinta M., Fajfer T., Fietkiewicz K., Dorosz D., Kowalski L., Olejnik J., Mularczyk K., and Zloczewski K. (2006). In Bastiaens L., Verbert J., Wislez J.-M., and Verbeeck C., editors, Proceedings of the International Meteor Conference, Oostmalle, Belgium, 15-18 September 2005, pages 53-62. IMO. Poleski R. and Szaruga K. (2006). In Bastiaens L., Verbert J., Wislez J.-M., and Verbeeck C., editors, Proceedings of the International Meteor

  14. Modeling Population Exposures to Silver Nanoparticles Present in Consumer Products

    PubMed Central

    Royce, Steven G.; Mukherjee, Dwaipayan; Cai, Ting; Xu, Shu S.; Alexander, Jocelyn A.; Mi, Zhongyuan; Calderon, Leonardo; Mainelis, Gediminas; Lee, KiBum; Lioy, Paul J.; Tetley, Teresa D.; Chung, Kian Fan; Zhang, Junfeng; Georgopoulos, Panos G.

    2014-01-01

    Exposures of the general population to manufactured nanoparticles (MNPs) are expected to keep rising due to increasing use of MNPs in common consumer products (PEN 2014). The present study focuses on characterizing ambient and indoor population exposures to silver MNPs (nAg). For situations where detailed, case-specific exposure-related data are not available, as in the present study, a novel tiered modeling system, Prioritization/Ranking of Toxic Exposures with GIS (Geographic Information System) Extension (PRoTEGE), has been developed: it employs a product Life Cycle Analysis (LCA) approach coupled with basic human Life Stage Analysis (LSA) to characterize potential exposures to chemicals of current and emerging concern. The PRoTEGE system has been implemented for ambient and indoor environments, utilizing available MNP production, usage, and properties databases, along with laboratory measurements of potential personal exposures from consumer spray products containing nAg. Modeling of environmental and microenvironmental levels of MNPs employs Probabilistic Material Flow Analysis combined with product LCA to account for releases during manufacturing, transport, usage, disposal, etc. Human exposure and dose characterization further employs screening Microenvironmental Modeling and Intake Fraction methods combined with LSA for potentially exposed populations, to assess differences associated with gender, age, and demographics. Population distributions of intakes, estimated using the PRoTEGE framework, are consistent with published individual-based intake estimates, demonstrating that PRoTEGE is capable of capturing realistic exposure scenarios for the US population. Distributions of intakes are also used to calculate biologically-relevant population distributions of uptakes and target tissue doses through human airway dosimetry modeling that takes into account product MNP size distributions and age-relevant physiological parameters. PMID:25745354

  15. Summing threshold logs in a parton shower

    NASA Astrophysics Data System (ADS)

    Nagy, Zoltán; Soper, Davison E.

    2016-10-01

    When parton distributions are falling steeply as the momentum fractions of the partons increases, there are effects that occur at each order in α s that combine to affect hard scattering cross sections and need to be summed. We show how to accomplish this in a leading approximation in the context of a parton shower Monte Carlo event generator.

  16. 49 CFR 228.321 - Showering facilities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., DEPARTMENT OF TRANSPORTATION HOURS OF SERVICE OF RAILROAD EMPLOYEES; RECORDKEEPING AND REPORTING; SLEEPING QUARTERS Safety and Health Requirements for Camp Cars Provided by Railroads as Sleeping Quarters § 228.321 Showering facilities. (a) Number. Each individual camp car that provides sleeping facilities must contain...

  17. Comet outbursts and the meteor showers

    NASA Astrophysics Data System (ADS)

    Guliyev, A. S.; Kokhirova, G. I.; Poladova, U. D.

    2014-07-01

    The features of 116 comets that have shown an outbursts in their brightness, are considered in the paper. The hypothesis on that the outburst in activity of comets are caused by their passing through meteoroid streams is studied. For this purpose the orbital elements of such comets relative to the planes of motion of 68 meteor showers from Cook's catalogue are analyzed. It was found that four of the nearest and distant nodes of comet orbits relative to the planes of motion of nine meteor showers exceeds the average statistical background with confidence probability from 0.90 to 0.95, and more than 0.95, respectively. The October Draconids, Aurigids, kappa-Serpentids, delta-Draconids, sigma-Hydrids}, Coma Berenicids, Leonids, Leo Minorids, and Perseids showers are the most effective. The results of calculation show that often, the comets outbursts may be caused by collisions of comets with meteoroids under the passing through the meteoroid streams that are producing listed meteor showers as well as solar activity.

  18. Search for bursts in air shower data

    NASA Technical Reports Server (NTRS)

    Bruce, T. E. G.; Clay, R. W.; Dawson, B. R.; Protheroe, R. J.; Blair, D. G.; Cinquini, P.

    1985-01-01

    There have been reports in recent years of the possible observation of bursts in air shower data. If such events are truly of an astrophysical nature then, they represent an important new class of phemonenon since no other bursts have been observed above the MeV level. The spectra of conventional gamma ray bursts are unknown at higher energies but their observed spectra at MeV energies appear generally to exhibit a steepening in the higher MeV range and are thus unlikely to extrapolate to measurable fluxes at air shower energies. An attempt has been made to look for deviations from randomness in the arrival times of air showers above approx. 10 to the 14th power eV with a number of systems and results so far are presented here. This work will be continued for a substantial period of ime with a system capable of recording bursts with multiple events down to a spacing of 4 microns. Earlier data have also been searched for the possible association of air shower events with a glitch of the Vela pulsar.

  19. Quark matter induced extensive air showers

    SciTech Connect

    Lawson, Kyle

    2011-05-15

    If the dark matter of our Galaxy is composed of nuggets of quarks or antiquarks in a color superconducting phase there will be a small but nonzero flux of these objects through the Earth's atmosphere. A nugget of quark matter will deposit only a small fraction of its kinetic energy in the atmosphere and is likely to be undetectable. If however the impacting object is composed of antiquarks, the energy deposited can be quite large. In this case nuclear annihilations within the nugget will trigger an extensive air shower the particle content of which is similar to that produced by an ultrahigh energy cosmic ray. This paper gives a qualitative description of the basic properties of such a shower. Several distinctions from an air shower initiated by a single ultrahigh energy nucleus will be described, allowing these events to be distinguished from the cosmic ray background. The subtlety of these features may mean that some fraction of the high energy cosmic ray spectrum may in fact be due to this type of dark matter interaction. The estimated flux of dark matter nuggets and the energy deposited in the atmosphere are such that the Pierre Auger Observatory may prove an ideal facility to place constraints on the flux of heavy quark matter objects. This paper attempts to highlight the best techniques to search for a quark matter signature through an extensive air shower signal.

  20. [Modification of postoperative wound healing by showering].

    PubMed

    Neues, C; Haas, E

    2000-02-01

    Usually postoperative wounds are kept dry until the stitches are removed. In a prospective randomized study early water contact was allowed in order to test postoperative wound healing in 817 patients operated on for varicose veins. Regardless of whether the wounds were kept dry or had water contact with or without shower foam from the second postoperative day, no infection was registered.

  1. Systematic Improvement of QCD Parton Showers

    SciTech Connect

    Winter, Jan; Hoeche, Stefan; Hoeth, Hendrik; Krauss, Frank; Schonherr, Marek; Zapp, Korinna; Schumann, Steffen; Siegert, Frank; /Freiburg U.

    2012-05-17

    In this contribution, we will give a brief overview of the progress that has been achieved in the field of combining matrix elements and parton showers. We exemplify this by focusing on the case of electron-positron collisions and by reporting on recent developments as accomplished within the SHERPA event generation framework.

  2. RECEPTOR MODELING OF AMBIENT AND PERSONAL EXPOSURE SAMPLES: 1998 BALTIMORE PARTICULATE MATTER EPIDEMIOLOGY-EXPOSURE STUDY

    EPA Science Inventory

    Sources of particulate matter exposure for an elderly population in a city north of Baltimore, MD were evaluated using advanced factor analysis models. Data collected with Versatile Air Pollutant Samplers (VAPS) positioned at a community site, outside and inside of an elderly ...

  3. A Revealing Exposure.

    ERIC Educational Resources Information Center

    Evans, Kenneth H.

    1992-01-01

    Describes an activity in which students examine hypothetical exposure to toxins by being showered by different colored pieces of confetti over several visits to exposure sites. Students record quantities of confetti that stick to packing tape. Colors correspond to different toxins posing different health problems. Students process their findings…

  4. Modelling of indoor exposure to nitrogen dioxide in the UK

    NASA Astrophysics Data System (ADS)

    Dimitroulopoulou, C.; Ashmore, M. R.; Byrne, M. A.; Kinnersley, R. P.

    A dynamic multi-compartment computer model has been developed to describe the physical processes determining indoor pollutant concentrations as a function of outdoor concentrations, indoor emission rates and building characteristics. The model has been parameterised for typical UK homes and workplaces and linked to a time-activity model to calculate exposures for a representative homemaker, schoolchild and office worker, with respect to NO 2. The estimates of population exposures, for selected urban and rural sites, are expressed in terms of annual means and frequency of hours in which air quality standards are exceeded. The annual mean exposures are estimated to fall within the range of 5-21 ppb for homes with no source, and 21-27 ppb for homes with gas cooking, varying across sites and population groups. The contribution of outdoor exposure to annual mean NO 2 exposure varied from 5 to 24%, that of indoor penetration of outdoor air from 17 to 86% and that of gas cooking from 0 to 78%. The frequency of exposure to 1 h mean concentrations above 150 ppb was very low, except for people cooking with gas.

  5. Source-to-Outcome Microbial Exposure and Risk Modeling Framework

    EPA Science Inventory

    A Quantitative Microbial Risk Assessment (QMRA) is a computer-based data-delivery and modeling approach that integrates interdisciplinary fate/transport, exposure, and impact models and databases to characterize potential health impacts/risks due to pathogens. As such, a QMRA ex...

  6. Extensive Air Showers and Cosmic Ray Physics above 1017 eV

    NASA Astrophysics Data System (ADS)

    Bertaina, Mario

    2016-07-01

    Cosmic Rays above 1017 eV allow studying hadronic interactions at energies that can not be attained at accelerators yet. At the same time hadronic interaction models have to be applied to the cosmic-ray induced air-shower cascades in atmosphere to infer the nature of cosmic rays. The reliability of air-shower simulations has become the source of one of the largest systematic uncertainty in the interpretation of cosmic-ray data due to the uncertainties in modeling the hadronic interaction driving the air-shower development. This paper summarises in the first part the recent results on the cosmic ray energy spectrum, composition and anisotropy from the knee region to the GZK cutoff [1, 2] of the spectrum by means of ground-based experiments. Most of the information reported in this contribution is taken from [3-5]. Aspects interconnecting cosmic ray and particle physics are reviewed in the second part of the paper.

  7. Full Monte-Carlo description of the Moscow State University Extensive Air Shower experiment

    NASA Astrophysics Data System (ADS)

    Fomin, Yu. A.; Kalmykov, N. N.; Karpikov, I. S.; Kulikov, G. V.; Kuznetsov, M. Yu.; Rubtsov, G. I.; Sulakov, V. P.; Troitsky, S. V.

    2016-08-01

    The Moscow State University Extensive Air Shower (EAS-MSU) array studied high-energy cosmic rays with primary energies ~ (1–500) PeV in the Northern hemisphere. The EAS-MSU data are being revisited following recently found indications to an excess of muonless showers, which may be interpreted as the first observation of cosmic gamma rays at ~ 100 PeV. In this paper, we present a complete Monte-Carlo model of the surface detector which results in a good agreement between data and simulations. The model allows us to study the performance of the detector and will be used to obtain physical results in further studies.

  8. Prediction of meteor shower associated with Comet 122P/de Vico

    NASA Astrophysics Data System (ADS)

    Tomko, Dusan; Neslusan, Lubos

    2013-01-01

    We model, for a far past, a theoretical stream associated with Comet 122P/de Vico and follow its dynamical evolution until present. Selecting the modeled particles approaching the Earth's orbit at the present, we predict the characteristics of a potential meteor shower and try to identify these particles with the meteors in three databases (photo, radar, and video). Our overall prediction is, however, negative because only the particles released from the comet nucleus before approximately 37 000 years ago are found to evolve into a collision course with the Earth and, therefore, form a possible shower. Meteoroids are known to survive a much shorter time in interplanetary space, unfortunately.

  9. Full Monte-Carlo description of the Moscow State University Extensive Air Shower experiment

    NASA Astrophysics Data System (ADS)

    Fomin, Yu. A.; Kalmykov, N. N.; Karpikov, I. S.; Kulikov, G. V.; Kuznetsov, M. Yu.; Rubtsov, G. I.; Sulakov, V. P.; Troitsky, S. V.

    2016-08-01

    The Moscow State University Extensive Air Shower (EAS-MSU) array studied high-energy cosmic rays with primary energies ~ (1-500) PeV in the Northern hemisphere. The EAS-MSU data are being revisited following recently found indications to an excess of muonless showers, which may be interpreted as the first observation of cosmic gamma rays at ~ 100 PeV. In this paper, we present a complete Monte-Carlo model of the surface detector which results in a good agreement between data and simulations. The model allows us to study the performance of the detector and will be used to obtain physical results in further studies.

  10. Accelerator Measurements of Magnetically Induced Radio Emission from Particle Cascades with Applications to Cosmic-Ray Air Showers.

    PubMed

    Belov, K; Mulrey, K; Romero-Wolf, A; Wissel, S A; Zilles, A; Bechtol, K; Borch, K; Chen, P; Clem, J; Gorham, P W; Hast, C; Huege, T; Hyneman, R; Jobe, K; Kuwatani, K; Lam, J; Liu, T C; Nam, J; Naudet, C; Nichol, R J; Rauch, B F; Rotter, B; Saltzberg, D; Schoorlemmer, H; Seckel, D; Strutt, B; Vieregg, A G; Williams, C

    2016-04-01

    For 50 years, cosmic-ray air showers have been detected by their radio emission. We present the first laboratory measurements that validate electrodynamics simulations used in air shower modeling. An experiment at SLAC provides a beam test of radio-frequency (rf) radiation from charged particle cascades in the presence of a magnetic field, a model system of a cosmic-ray air shower. This experiment provides a suite of controlled laboratory measurements to compare to particle-level simulations of rf emission, which are relied upon in ultrahigh-energy cosmic-ray air shower detection. We compare simulations to data for intensity, linearity with magnetic field, angular distribution, polarization, and spectral content. In particular, we confirm modern predictions that the magnetically induced emission in a dielectric forms a cone that peaks at the Cherenkov angle and show that the simulations reproduce the data within systematic uncertainties.

  11. Accelerator Measurements of Magnetically Induced Radio Emission from Particle Cascades with Applications to Cosmic-Ray Air Showers

    NASA Astrophysics Data System (ADS)

    Belov, K.; Mulrey, K.; Romero-Wolf, A.; Wissel, S. A.; Zilles, A.; Bechtol, K.; Borch, K.; Chen, P.; Clem, J.; Gorham, P. W.; Hast, C.; Huege, T.; Hyneman, R.; Jobe, K.; Kuwatani, K.; Lam, J.; Liu, T. C.; Nam, J.; Naudet, C.; Nichol, R. J.; Rauch, B. F.; Rotter, B.; Saltzberg, D.; Schoorlemmer, H.; Seckel, D.; Strutt, B.; Vieregg, A. G.; Williams, C.; T-510 Collaboration

    2016-04-01

    For 50 years, cosmic-ray air showers have been detected by their radio emission. We present the first laboratory measurements that validate electrodynamics simulations used in air shower modeling. An experiment at SLAC provides a beam test of radio-frequency (rf) radiation from charged particle cascades in the presence of a magnetic field, a model system of a cosmic-ray air shower. This experiment provides a suite of controlled laboratory measurements to compare to particle-level simulations of rf emission, which are relied upon in ultrahigh-energy cosmic-ray air shower detection. We compare simulations to data for intensity, linearity with magnetic field, angular distribution, polarization, and spectral content. In particular, we confirm modern predictions that the magnetically induced emission in a dielectric forms a cone that peaks at the Cherenkov angle and show that the simulations reproduce the data within systematic uncertainties.

  12. Accelerator Measurements of Magnetically Induced Radio Emission from Particle Cascades with Applications to Cosmic-Ray Air Showers.

    PubMed

    Belov, K; Mulrey, K; Romero-Wolf, A; Wissel, S A; Zilles, A; Bechtol, K; Borch, K; Chen, P; Clem, J; Gorham, P W; Hast, C; Huege, T; Hyneman, R; Jobe, K; Kuwatani, K; Lam, J; Liu, T C; Nam, J; Naudet, C; Nichol, R J; Rauch, B F; Rotter, B; Saltzberg, D; Schoorlemmer, H; Seckel, D; Strutt, B; Vieregg, A G; Williams, C

    2016-04-01

    For 50 years, cosmic-ray air showers have been detected by their radio emission. We present the first laboratory measurements that validate electrodynamics simulations used in air shower modeling. An experiment at SLAC provides a beam test of radio-frequency (rf) radiation from charged particle cascades in the presence of a magnetic field, a model system of a cosmic-ray air shower. This experiment provides a suite of controlled laboratory measurements to compare to particle-level simulations of rf emission, which are relied upon in ultrahigh-energy cosmic-ray air shower detection. We compare simulations to data for intensity, linearity with magnetic field, angular distribution, polarization, and spectral content. In particular, we confirm modern predictions that the magnetically induced emission in a dielectric forms a cone that peaks at the Cherenkov angle and show that the simulations reproduce the data within systematic uncertainties. PMID:27104694

  13. Activity and observability of meteor showers throughout the year

    NASA Astrophysics Data System (ADS)

    Zimnikoval, Peter

    2014-02-01

    Diagrams on the poster present the activity periods of meteor showers as well as the rising and setting times of meteor shower radiants. Plotted are sunrises, sunsets and the period of twilight. It was constructed according to data from the IMO Meteor Shower Working List. More active showers are displayed in red and less active showers in green. The diagrams are calculated for geographic latitudes of 40° N, 0° and 40° S. The time scale is given as local time at the relevant zonal meridian and supplemented by local daylight saving time. The diagrams contain rounded values of solar longitude J2000. The star chart shows the radiant positions and drift of IMO meteor showers while the other diagrams display shower activity and date of maximum.

  14. Spatial aspects of building and population exposure data and their implications for global earthquake exposure modeling

    USGS Publications Warehouse

    Dell’Acqua, F.; Gamba, P.; Jaiswal, K.

    2012-01-01

    This paper discusses spatial aspects of the global exposure dataset and mapping needs for earthquake risk assessment. We discuss this in the context of development of a Global Exposure Database for the Global Earthquake Model (GED4GEM), which requires compilation of a multi-scale inventory of assets at risk, for example, buildings, populations, and economic exposure. After defining the relevant spatial and geographic scales of interest, different procedures are proposed to disaggregate coarse-resolution data, to map them, and if necessary to infer missing data by using proxies. We discuss the advantages and limitations of these methodologies and detail the potentials of utilizing remote-sensing data. The latter is used especially to homogenize an existing coarser dataset and, where possible, replace it with detailed information extracted from remote sensing using the built-up indicators for different environments. Present research shows that the spatial aspects of earthquake risk computation are tightly connected with the availability of datasets of the resolution necessary for producing sufficiently detailed exposure. The global exposure database designed by the GED4GEM project is able to manage datasets and queries of multiple spatial scales.

  15. AVAILABLE MICRO-ACTIVITY DATA AND THEIR APPLICABILITY TO AGGREGATE EXPOSURE MODELING

    EPA Science Inventory

    Several human exposure models have been developed in recent years to address children's aggregate and cumulative exposures to pesticides under the Food Quality Protection Act of 1996. These models estimate children's exposures via all significant routes and pathways including ...

  16. A dermal model for spray painters. Part I: subjective exposure modelling of spray paint deposition.

    PubMed

    Brouwer, D H; Semple, S; Marquart, J; Cherrie, J W

    2001-01-01

    The discriminative power of existing dermal exposure models is limited. Most models only allow occupational hygienists to rank workers between and within workplaces according to broad bands of dermal exposure. No allowance is made for the work practices of different individuals. In this study a process-based, structured approach has been used to estimate dermal exposure from overspray generated by a spray painting process. Factors for spray technique, object shape and workers' individual work practices involved in the processes of droplet formation and deposition were incorporated into the model. The model was applied to predict dermal exposure of airless spray painters and the results were compared with exposure data. The predicted levels of exposure showed reasonable rank correlation with the measured exposure, although the model tended to over-predict the actual level of exposure. It was concluded that a structured, process-based approach has the potential to produce reliable estimates of dermal exposure. The reliability of exposure models of this type should be explored further and the relationship between the determinants of exposure should be validated by additional field studies. PMID:11137695

  17. Model of spacecraft atomic oxygen and solar exposure microenvironments

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  18. An improved model for the reconstruction of past radon exposure

    SciTech Connect

    Cauwels, P.; Poffijn, A.

    2000-05-01

    If the behavior of long-lived radon progeny was well understood, measurements of these could be used in epidemiological studies to estimate past radon exposure. Field measurements were done in a radon-prone area in the Ardennes (Belgium). The surface activity of several glass sheets was measured using detectors that were fixed on indoor glass surfaces. Simultaneously the indoor radon concentration was measured using diffusion chambers. By using Monte Carlo techniques, it could be proven that there is a discrepancy between this data set and the room model calculations, which are normally used to correlate surface activity and past radon exposure. To solve this, a modification of the model is proposed.

  19. The 2011 Draconid Shower Risk to Earth-Orbiting Satellites

    NASA Technical Reports Server (NTRS)

    Cooke, William J.; Moser, Danielle E.

    2010-01-01

    Current meteor shower forecast models project a strong Draconid outburst, possibly a storm, on October 8, 2011, with a duration of approximately 7 hours and peaking between 19 and 21 hours UT. Predicted rates span an order of magnitude, with maximum Zenithal Hourly Rates (ZHRs) ranging from a few tens to several hundred. Calibration of the NASA MSFC Meteoroid Stream Model 1 to radar and optical observations of past apparitions, particularly the 2005 Draconid outburst 2, suggest that the maximum rate will be several hundreds per hour. Given the high spatial density of the Draconid stream, this implies a maximum meteoroid flux of 5-10 Draconids km(exp -2)/hr (to a limiting diameter of 1 mm), some 25-50 times greater than the normal sporadic flux of 0.2 km(exp -2)/ hr for particles of this size. Total outburst fluence, assuming a maximum ZHR of 750, is 15.5 Draconids km(exp -2), resulting in an overall 10x risk increase to spacecraft surfaces vulnerable to hypervelocity impacts by 1 mm particles. It is now established that a significant fraction of spacecraft anomalies produced by shower meteoroids (e.g. OLYMPUS and LandSat 5) are caused by electrostatic discharges produced by meteoroid impacts. In these cases, the charge generated is roughly proportional to v(exp 3.5(4)), giving a Draconid moving at 20 km/s approximately 1/80th the electrical damage potential of a Leonid of the same mass. In other words, a Draconid outburst with a maximum ZHR of 800 presents the same electrical risk as a normal Leonid shower with a ZHR of 15, assuming the mass indices and shower durations are the same. This is supported by the fact that no spacecraft electrical anomalies were reported during the strong Draconid outbursts of 1985 and 1998. However, the lack of past anomalies should not be taken as carte blanche for satellite operators to ignore the 2011 Draconids, as the upcoming outburst will constitute a period of enhanced risk for vehicles in near-Earth space. Each spacecrft is

  20. Adjusting exposure limits for long and short exposure periods using a physiological pharmacokinetic model

    SciTech Connect

    Andersen, M.E.; MacNaughton, M.G.; Clewell, H.J. III; Paustenbach, D.J.

    1987-04-01

    This paper advocates use of a physiologically-based pharmacokinetic (PB-PK) model for determining adjustment factors for unusual exposure schedules. The PB-PK model requires data on the blood:air and tissue:blood partition coefficients, the rate of metabolism of the chemical, organ volumes, organ blood flows and ventilation rates in humans. Laboratory data on two industrially important chemicals - styrene and methylene chloride - were used to illustrate the PB-PK approach. At inhaled concentrations near their respective 8-hr Threshold Limit Value - Time-weighted averages both of these chemicals are primarily eliminated from the body by metabolism. For these two chemicals, the appropriate risk indexing parameters are integrated tissue dose or total amount of parent chemical metabolized. These examples also illustrate how the model can be used to calculate risk based on various other measures of delivered dose. For the majority of volatile chemicals, the parameter most closely associated with risk is the integrated tissue dose. This analysis suggests that when pharmacokinetic data are not available, a simple inverse formula may be sufficient for adjustment in most instances and application of complex kinetic models unnecessary. At present, this PB-PK approach is recommended only for exposure periods of 4 to 16 hr/day, because the mechanisms of toxicity for some chemicals may vary for very short- or very long-term exposures. For these altered schedules, more biological information on recovery in rest periods and changing mechanisms of toxicity are necessary before any adjustment is attempted.

  1. Prediction of evolution of meteor shower associated with comet 122P/de Vico

    NASA Astrophysics Data System (ADS)

    Tomko, D.

    2014-04-01

    We deal with a theoretical meteoroid stream of the comet 122P/de Vico. For five perihelion passages in the distant past, we model a theoretical stream and follow its dynamical evolution until the present. We predict the characteristics of potential a meteor shower approaching the Earth's orbit and we make also the identification of the particles of the predicted shower with the real meteors in three databases (photo, radar, and video). Our overall prediction is, however, negative because only the particles released from the comet nucleus before approximately 37 000 years are found to evolve into a collision course with the Earth and, therefore, form a possible shower. Many meteoroids do not survive such a long time in interplanetary space.

  2. Muons in air showers at the Pierre Auger Observatory: Measurement of atmospheric production depth

    NASA Astrophysics Data System (ADS)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Al Samarai, I.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; Dorosti Hasankiadeh, Q.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fox, B. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Fuji, T.; Gaior, R.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gate, F.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Islo, K.; Jandt, I.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, A. J.; Matthews, J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Ochilo, L.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; PÈ©kala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Peters, C.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Taborda, O. A.; Tapia, A.; Tartare, M.; Thao, N. T.; Theodoro, V. M.; Tiffenberg, J.; Timmermans, C.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Vlcek, B.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Whelan, B. J.; Widom, A.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Pierre Auger Collaboration

    2014-07-01

    The surface detector array of the Pierre Auger Observatory provides information about the longitudinal development of the muonic component of extensive air showers. Using the timing information from the flash analog-to-digital converter traces of surface detectors far from the shower core, it is possible to reconstruct a muon production depth distribution. We characterize the goodness of this reconstruction for zenith angles around 60° and different energies of the primary particle. From these distributions, we define Xmaxμ as the depth along the shower axis where the production of muons reaches maximum. We explore the potentiality of Xmaxμ as a useful observable to infer the mass composition of ultrahigh-energy cosmic rays. Likewise, we assess its ability to constrain hadronic interaction models.

  3. Reconstruction of inclined air showers detected with the Pierre Auger Observatory

    SciTech Connect

    Collaboration: Pierre Auger Collaboration

    2014-08-01

    We describe the method devised to reconstruct inclined cosmic-ray air showers with zenith angles greater than 60° detected with the surface array of the Pierre Auger Observatory. The measured signals at the ground level are fitted to muon density distributions predicted with atmospheric cascade models to obtain the relative shower size as an overall normalization parameter. The method is evaluated using simulated showers to test its performance. The energy of the cosmic rays is calibrated using a sub-sample of events reconstructed with both the fluorescence and surface array techniques. The reconstruction method described here provides the basis of complementary analyses including an independent measurement of the energy spectrum of ultra-high energy cosmic rays using very inclined events collected by the Pierre Auger Observatory.

  4. Reconstruction of inclined air showers detected with the Pierre Auger Observatory

    SciTech Connect

    Aab, Alexander; et al.

    2014-08-08

    We describe the method devised to reconstruct inclined cosmic-ray air showers with zenith angles greater than 60° detected with the surface array of the Pierre Auger Observatory. The measured signals at the ground level are fitted to muon density distributions predicted with atmospheric cascade models to obtain the relative shower size as an overall normalization parameter. The method is evaluated using simulated showers to test its performance. The energy of the cosmic rays is calibrated using a sub-sample of events reconstructed with both the fluorescence and surface array techniques. The reconstruction method described here provides the basis of complementary analyses including an independent measurement of the energy spectrum of ultra-high energy cosmic rays using very inclined events collected by the Pierre Auger Observatory.

  5. MAVEN IUVS observations of the aftermath of the Comet Siding Spring meteor shower on Mars

    NASA Astrophysics Data System (ADS)

    Schneider, N. M.; Deighan, J. I.; Stewart, A. I. F.; McClintock, W. E.; Jain, S. K.; Chaffin, M. S.; Stiepen, A.; Crismani, M.; Plane, J. M. C.; Carrillo-Sánchez, J. D.; Evans, J. S.; Stevens, M. H.; Yelle, R. V.; Clarke, J. T.; Holsclaw, G. M.; Montmessin, F.; Jakosky, B. M.

    2015-06-01

    We report the detection of intense emission from magnesium and iron in Mars' atmosphere caused by a meteor shower following Comet Siding Spring's close encounter with Mars. The observations were made with the Imaging Ultraviolet Spectrograph, a remote sensing instrument on the Mars Atmosphere and Volatile EvolutioN spacecraft orbiting Mars. Ionized magnesium caused the brightest emission from the planet's atmosphere for many hours, resulting from resonant scattering of solar ultraviolet light. Modeling suggests a substantial fluence of low-density dust particles 1-100 µm in size, with the large amount and small size contrary to predictions. The event created a temporary planet-wide ionospheric layer below Mars' main dayside ionosphere. The dramatic meteor shower response at Mars is starkly different from the case at Earth, where a steady state metal layer is always observable but perturbations caused by even the strongest meteor showers are challenging to detect.

  6. AN OVERVIEW OF HUMAN EXPOSURE MODELING ACTIVITIES AT THE U.S. EPA'S NATIONAL EXPOSURE RESEARCH LABORATORY

    EPA Science Inventory

    The computational modeling of human exposure to environmental pollutants is one of the primary activities of the US Environmental Protection Agency (USEPA)'s National Exposure Research Laboratory (NERL). Assessment of human exposures is a critical part of the overall risk assessm...

  7. Volatilization of chemicals from tap water to indoor air from contaminated water used for showering

    SciTech Connect

    Moya, J. . National Center for Environmental Assessment); Howard-Reed, C.; Corsi, R.L. . Dept. of Civil Engineering)

    1999-07-15

    Volatile organic compounds (VOCs) may enter indoor air during the use of contaminated tap water. When this occurs, occupants can become exposed to potentially toxic VOCs via the inhalation route. The propensity for VOCs to volatilize into indoor air during the routine use of showers was investigated. A series of mass transfer experiments were conducted while a shower was operated within an enclosed chamber. Acetone, ethyl acetate, toluene, ethylbenzene, and cyclohexane were used as volatile tracers. Chemical-specific stripping efficiencies and mass transfer coefficients were determined. An assessment of the importance of gas-phase resistance to mass transfer from water to air was also completed. Chemical-specific stripping efficiencies ranged from 6.3% (for acetone) to 80% (for cyclohexane) for household showers used under normal conditions. As described in this paper, data resulting from this study allow for the determination of overall mass transfer coefficients, and corresponding volatilization rates, for any showering event and chemical of interest. As such, the information presented herein should lead to improved estimates of human inhalation exposure to toxic chemicals that volatilize from water to indoor air.

  8. Results of Lunar Impact Observations During Geminid Meteor Shower Events

    NASA Technical Reports Server (NTRS)

    Suggs, R. J.; Suggs, R. M.

    2015-01-01

    the lunar environment associated with larger lunar impactors, but also provides statistical data for verification and improving meteoroid prediction models. Current meteoroid models indicate that the Moon is struck by a sporadic meteoroid with a mass greater than 1 kg over 260 times per year. This number is very uncertain since observations for objects in this mass range are few. Factors of several times, higher or lower, are easily possible. Meteor showers are also present to varying degrees at certain times of the year. The Earth experiences meteor showers when encountering the debris left behind by comets, which is also the case with 2 the Moon. During such times, the rate of shower meteoroids can greatly exceed that of the sporadic background rate for larger meteoroids. Looking for meteor shower impacts on the Moon at about the same time as they occur on Earth will yield important data that can be fed into meteor shower forecasting models, which can then be used to predict times of greater meteoroid hazard on the Moon. The Geminids are one such meteor shower of interest. The Geminids are a major meteor shower that occur in December with a peak intensity occurring usually during the 13th and 14th of the month and appearing to come from a radiant in the constellation Gemini. The Geminids are interesting in that the parent body of the debris stream is an asteroid, which along with the Quadrantids, are the only major meteor showers not originating from a comet. The Geminids parent body, 3200 Phaethon, is about 5 km in diameter and has an orbit that has a 22deg inclination which intersects the main asteroid belt and has a perihelion less than half of Mercury's perihelion distance. Thus, its orbit crosses those of Mars, Earth, Venus, and Mercury. The Geminid debris stream is by far the most massive as compared to the others. When the Earth passes through the stream in mid-December, a peak intensity of approx. equal 120 meteors per hour can be seen. Because of the

  9. Hard photon production and matrix-element parton-shower merging

    SciTech Connect

    Hoeche, Stefan; Schumann, Steffen; Siegert, Frank

    2010-02-01

    We present a Monte Carlo approach to prompt-photon production, where photons and QCD partons are treated democratically. The photon fragmentation function is modeled by an interleaved QCD+QED parton shower. This known technique is improved by including higher-order real-emission matrix elements. To this end, we extend a recently proposed algorithm for merging matrix elements and truncated parton showers. We exemplify the quality of the Monte Carlo predictions by comparing them to measurements of the photon fragmentation function at LEP and to measurements of prompt photon and diphoton production from the Tevatron experiments.

  10. EXPOSURE VERSION 2 - A COMPUTER MODEL FOR ANALYZING THE EFFECTS OF INDOOR AIR POLLUTANT SOURCES ON INDIVIDUAL EXPOSURE

    EPA Science Inventory

    The report presents a model for calculating individual exposure to indoor pollutants from sources. The model calculates exposure due to individual, as opposed to population, activity patterns and source use. The model uses data on source emissions, room- to- room air flows, air e...

  11. Longitudinal development of extensive air showers: Hybrid code SENECA and full Monte Carlo

    NASA Astrophysics Data System (ADS)

    Ortiz, Jeferson A.; Medina-Tanco, Gustavo; de Souza, Vitor

    2005-06-01

    New experiments, exploring the ultra-high energy tail of the cosmic ray spectrum with unprecedented detail, are exerting a severe pressure on extensive air shower modelling. Detailed fast codes are in need in order to extract and understand the richness of information now available. Some hybrid simulation codes have been proposed recently to this effect (e.g., the combination of the traditional Monte Carlo scheme and system of cascade equations or pre-simulated air showers). In this context, we explore the potential of SENECA, an efficient hybrid tri-dimensional simulation code, as a valid practical alternative to full Monte Carlo simulations of extensive air showers generated by ultra-high energy cosmic rays. We extensively compare hybrid method with the traditional, but time consuming, full Monte Carlo code CORSIKA which is the de facto standard in the field. The hybrid scheme of the SENECA code is based on the simulation of each particle with the traditional Monte Carlo method at two steps of the shower development: the first step predicts the large fluctuations in the very first particle interactions at high energies while the second step provides a well detailed lateral distribution simulation of the final stages of the air shower. Both Monte Carlo simulation steps are connected by a cascade equation system which reproduces correctly the hadronic and electromagnetic longitudinal profile. We study the influence of this approach on the main longitudinal characteristics of proton, iron nucleus and gamma induced air showers and compare the predictions of the well known CORSIKA code using the QGSJET hadronic interaction model.

  12. Stoffenmanager exposure model: development of a quantitative algorithm.

    PubMed

    Tielemans, Erik; Noy, Dook; Schinkel, Jody; Heussen, Henri; Van Der Schaaf, Doeke; West, John; Fransman, Wouter

    2008-08-01

    In The Netherlands, the web-based tool called 'Stoffenmanager' was initially developed to assist small- and medium-sized enterprises to prioritize and control risks of handling chemical products in their workplaces. The aim of the present study was to explore the accuracy of the Stoffenmanager exposure algorithm. This was done by comparing its semi-quantitative exposure rankings for specific substances with exposure measurements collected from several occupational settings to derive a quantitative exposure algorithm. Exposure data were collected using two strategies. First, we conducted seven surveys specifically for validation of the Stoffenmanager. Second, existing occupational exposure data sets were collected from various sources. This resulted in 378 and 320 measurements for solid and liquid scenarios, respectively. The Spearman correlation coefficients between Stoffenmanager scores and exposure measurements appeared to be good for handling solids (r(s) = 0.80, N = 378, P < 0.0001) and liquid scenarios (r(s) = 0.83, N = 320, P < 0.0001). However, the correlation for liquid scenarios appeared to be lower when calculated separately for sets of volatile substances with a vapour pressure >10 Pa (r(s) = 0.56, N = 104, P < 0.0001) and non-volatile substances with a vapour pressure < or =10 Pa (r(s) = 0.53, N = 216, P < 0.0001). The mixed-effect regression models with natural log-transformed Stoffenmanager scores as independent parameter explained a substantial part of the total exposure variability (52% for solid scenarios and 76% for liquid scenarios). Notwithstanding the good correlation, the data show substantial variability in exposure measurements given a certain Stoffenmanager score. The overall performance increases our confidence in the use of the Stoffenmanager as a generic tool for risk assessment. The mixed-effect regression models presented in this paper may be used for assessment of so-called reasonable worst case exposures. This evaluation is

  13. Personal exposure meets risk assessment: a comparison of measured and modeled exposures and risks in an urban community.

    PubMed Central

    Payne-Sturges, Devon C; Burke, Thomas A; Breysse, Patrick; Diener-West, Marie; Buckley, Timothy J

    2004-01-01

    Human exposure research has consistently shown that, for most volatile organic compounds (VOCs), personal exposures are vastly different from outdoor air concentrations. Therefore, risk estimates based on ambient measurements may over- or underestimate risk, leading to ineffective or inefficient management strategies. In the present study we examine the extent of exposure misclassification and its impact on risk for exposure estimated by the U.S. Environmental Protection Agency (U.S. EPA) Assessment System for Population Exposure Nationwide (ASPEN) model relative to monitoring results from a community-based exposure assessment conducted in Baltimore, Maryland (USA). This study is the first direct comparison of the ASPEN model (as used by the U.S. EPA for the Cumulative Exposure Project and subsequently the National-Scale Air Toxics Assessment) and human exposure data to estimate health risks. A random sampling strategy was used to recruit 33 nonsmoking adult community residents. Passive air sampling badges were used to assess 3-day time-weighted-average personal exposure as well as outdoor and indoor residential concentrations of VOCs for each study participant. In general, personal exposures were greater than indoor VOC concentrations, which were greater than outdoor VOC concentrations. Public health risks due to actual personal exposures were estimated. In comparing measured personal exposures and indoor and outdoor VOC concentrations with ASPEN model estimates for ambient concentrations, our data suggest that ASPEN was reasonably accurate as a surrogate for personal exposures (measured exposures of community residents) for VOCs emitted primarily from mobile sources or VOCs that occur as global "background" source pollutant with no indoor source contributions. Otherwise, the ASPEN model estimates were generally lower than measured personal exposures and the estimated health risks. ASPEN's lower exposures resulted in proportional underestimation of cumulative

  14. Sex Differences in Adolescent Depression: Stress Exposure and Reactivity Models

    ERIC Educational Resources Information Center

    Hankin, Benjamin L.; Mermelstein, Robin; Roesch, Linda

    2007-01-01

    Stress exposure and reactivity models were examined as explanations for why girls exhibit greater levels of depressive symptoms than boys. In a multiwave, longitudinal design, adolescents' depressive symptoms, alcohol usage, and occurrence of stressors were assessed at baseline, 6, and 12 months later (N=538; 54.5% female; ages 13-18, average…

  15. REGRESSION MODELS OF RESIDENTIAL EXPOSURE TO CHLORPYRIFOS AND DIAZINON

    EPA Science Inventory

    This study examines the ability of regression models to predict residential exposures to chlorpyrifos and diazinon, based on the information from the NHEXAS-AZ database. The robust method was used to generate "fill-in" values for samples that are below the detection l...

  16. Analyses of School Commuting Data for Exposure Modeling Purposes

    EPA Science Inventory

    Human exposure models often make the simplifying assumption that school children attend school in the same Census tract where they live. This paper analyzes that assumption and provides information on the temporal and spatial distributions associated with school commuting. The d...

  17. MODELING EXPOSURES TO PESTICIDES APPROACHES AND MODELING NEEDS

    EPA Science Inventory

    Estimation of exposures of children to pesticides requires careful consideration of sources and concentrations of pesticides that may be present in different environmental media and in foods and beverages consumed by children, as well as the different routes and pathways of exp...

  18. Air Shower Detection by Bistatic Radar

    NASA Astrophysics Data System (ADS)

    Othman, M. Abou Bakr; Allen, C.; Belz, J.; Besson, D.; Farhang-Boroujeny, B.; Ikeda, D.; Kunwar, S.; Lundquist, J. P.; Kravchenko, I.; Myers, I.; Nakamura, T.; Sagawa, H.; Sokolsky, P.; Takai, H.; Terasawa, T.; Thomson, G. B.

    2011-09-01

    Progress in the field of high-energy cosmic rays is currently limited by the rarity of the most interesting rays striking the Earth. Indeed, the continuation of the field beyond the current generation of observatories may become financially and practically impossible if new ways are not found to achieve remote coverage over large portions of the Earth's surface. We describe the development of an observatory based on such a new technique: the remote sensing via bistatic radar technology of cosmic ray induced extensive air showers. We build on pilot studies performed by MARIACHI which have demonstrated that air shower radar echoes are detectable, the opportunity afforded by the location of the Northern Hemisphere's largest ``conventional'' cosmic ray observatory (The Telescope Array) in radio-quiet western Utah, and the donation of analog television transmission equipment to this effort by a local television station.

  19. A Simple shower and matching algorithm

    SciTech Connect

    Giele, Walter T.; Kosower, David A.; Skands, Peter Z.; /Fermilab

    2007-07-01

    We present a simple formalism for parton-shower Markov chains. As a first step towards more complete 'uncertainty bands', we incorporate a comprehensive exploration of the ambiguities inherent in such calculations. To reduce this uncertainty, we then introduce a matching formalism which allows a generated event sample to simultaneously reproduce any infrared safe distribution calculated at leading or next-to-leading order in perturbation theory, up to sub-leading corrections. To enable a more universal definition of perturbative calculations, we also propose a more general definition of the hadronization cutoff. Finally, we present an implementation of some of these ideas for final-state gluon showers, in a code dubbed VINCIA.

  20. Parameterization models for pesticide exposure via crop consumption.

    PubMed

    Fantke, Peter; Wieland, Peter; Juraske, Ronnie; Shaddick, Gavin; Itoiz, Eva Sevigné; Friedrich, Rainer; Jolliet, Olivier

    2012-12-01

    An approach for estimating human exposure to pesticides via consumption of six important food crops is presented that can be used to extend multimedia models applied in health risk and life cycle impact assessment. We first assessed the variation of model output (pesticide residues per kg applied) as a function of model input variables (substance, crop, and environmental properties) including their possible correlations using matrix algebra. We identified five key parameters responsible for between 80% and 93% of the variation in pesticide residues, namely time between substance application and crop harvest, degradation half-lives in crops and on crop surfaces, overall residence times in soil, and substance molecular weight. Partition coefficients also play an important role for fruit trees and tomato (Kow), potato (Koc), and lettuce (Kaw, Kow). Focusing on these parameters, we develop crop-specific models by parametrizing a complex fate and exposure assessment framework. The parametric models thereby reflect the framework's physical and chemical mechanisms and predict pesticide residues in harvest using linear combinations of crop, crop surface, and soil compartments. Parametric model results correspond well with results from the complex framework for 1540 substance-crop combinations with total deviations between a factor 4 (potato) and a factor 66 (lettuce). Predicted residues also correspond well with experimental data previously used to evaluate the complex framework. Pesticide mass in harvest can finally be combined with reduction factors accounting for food processing to estimate human exposure from crop consumption. All parametric models can be easily implemented into existing assessment frameworks. PMID:23136826

  1. Parameterization models for pesticide exposure via crop consumption.

    PubMed

    Fantke, Peter; Wieland, Peter; Juraske, Ronnie; Shaddick, Gavin; Itoiz, Eva Sevigné; Friedrich, Rainer; Jolliet, Olivier

    2012-12-01

    An approach for estimating human exposure to pesticides via consumption of six important food crops is presented that can be used to extend multimedia models applied in health risk and life cycle impact assessment. We first assessed the variation of model output (pesticide residues per kg applied) as a function of model input variables (substance, crop, and environmental properties) including their possible correlations using matrix algebra. We identified five key parameters responsible for between 80% and 93% of the variation in pesticide residues, namely time between substance application and crop harvest, degradation half-lives in crops and on crop surfaces, overall residence times in soil, and substance molecular weight. Partition coefficients also play an important role for fruit trees and tomato (Kow), potato (Koc), and lettuce (Kaw, Kow). Focusing on these parameters, we develop crop-specific models by parametrizing a complex fate and exposure assessment framework. The parametric models thereby reflect the framework's physical and chemical mechanisms and predict pesticide residues in harvest using linear combinations of crop, crop surface, and soil compartments. Parametric model results correspond well with results from the complex framework for 1540 substance-crop combinations with total deviations between a factor 4 (potato) and a factor 66 (lettuce). Predicted residues also correspond well with experimental data previously used to evaluate the complex framework. Pesticide mass in harvest can finally be combined with reduction factors accounting for food processing to estimate human exposure from crop consumption. All parametric models can be easily implemented into existing assessment frameworks.

  2. A new study of muons in air showers by NBU air shower array

    NASA Technical Reports Server (NTRS)

    Chaudhuri, N.; Mukherjee, N.; Sarkar, S.; Basak, D. K.; Ghosh, B.

    1985-01-01

    The North Bengal University (NBU) air shower array has been in operation in conjunction with two muon magnetic spectrographs. The array incorporates 21 particle density sampling detectors around the magnetic spectrographs covering an area of 900 sq m. The layout of the array is based on the arrangement of detectors in a square symmetry. The array set up on the ground level is around a 10 m high magnetic spectrograph housing. This magnetic spectrograph housing limits the zenith angular acceptance of the incident showers to a few degrees. Three hundred muons in the fitted showers of size range 10 to the 4th power to 10 to the 5th power particles have so far been scanned and the momenta determined in the momentum range 2 - 440 GeV/c. More than 1500 recorded showers are now in the process of scanning and fitting. A lateral distribution of muons of energy greater than 300 MeV in the shower size range 10 to the 5th power to 7 x 10 to the 5th power has been obtained.

  3. The World's Most Famous Meteor Shower Picture

    NASA Astrophysics Data System (ADS)

    Hughes, David W.

    1995-01-01

    The world's most famous meteor shower picture (Fig. 1) is of the storm that took place in the early morning of Wednesday, 13 November 1833. The picture was, however, produce 54 years after the event, being first published in April 1888. It had a biblical origin and was only taken over by the astronomers in the mid 1920s. The artist was the Swiss painter Karl Jauslin and the engraver was Adolf Völlmy.

  4. The midpoint between dipole and parton showers

    SciTech Connect

    Höche, Stefan; Prestel, Stefan

    2015-09-28

    We present a new parton-shower algorithm. Borrowing from the basic ideas of dipole cascades, the evolution variable is judiciously chosen as the transverse momentum in the soft limit. This leads to a very simple analytic structure of the evolution. A weighting algorithm is implemented that allows one to consistently treat potentially negative values of the splitting functions and the parton distributions. Thus, we provide two independent, publicly available implementations for the two event generators PYTHIA and SHERPA.

  5. David Levy's Guide to Observing Meteor Showers

    NASA Astrophysics Data System (ADS)

    Levy, David H.

    2007-11-01

    Preface; 1. July 4, 1956; 2. What is a meteor?; 3. Some historical notes; 4. Small rocks and dust in space; 5. Observing meteors; 6. Recording meteors; 7. Quadrantids; 8. Lyrids; 9. The Eta Aquarids; 10. The Omicron Draconids; 11. Delta Aquarids; 12. Perseids; 13. The Gamma Pavonids; 14. Orionids; 15. Taurids; 16. Leonids; 17. Geminids; 18. Ursids; 19. Meteor showers throughout the year; Appendix.

  6. An analytical approach to fluctuations in showers

    NASA Astrophysics Data System (ADS)

    Vázquez, R. A.

    1997-03-01

    We review the problem of fluctuations in particle shower theory. By using a generalization of Furry equation, we find relations between the n-particle correlation function and the number of particles average or 1-particle correlation function. Such relations show that the average is the only independent dynamical variable. We also develop a numerical code to solve the equation for the correlation functions and compare the results with those from a Monte Carlo simulation which show a perfect agreement between both methods.

  7. Meteors and showers a millennium ago

    NASA Astrophysics Data System (ADS)

    Ahn, Sang-Hyeon

    2003-08-01

    Meteors can be classified into either sporadic meteors or showery meteors. We compile the meteor records in the astronomical archives in the chronicle of the Koryo dynasty (918-1392), and investigate the spatial distribution of meteor streams along the orbit of the Earth from the 10th to the 14th century. We see that meteors from meteor streams signalize themselves over noisy sporadic meteors, and that the seasonal activity of sporadic meteors is apparently regular. We discover the presence of a few meteor streams by analysing about 700 meteors in the Koryo period. We also compile the records of meteor showers and storms in the chronicles of Korea, Japan, China, Arabia and Europe, and compare their appearance dates with those of showers obtained in our analysis, as well as with the modern observations. We confirm that the three sets of data are in agreement with each other. The representative meteor showers are the Perseids, the Leonids, and the η Aquarids/Orionids pair formed by Halley's comet. The other weak or relic meteor streams are also observable but uncertain. Hence we witness the regularity of meteor activity, which is seen to persist for a millennium.

  8. Radar observations of the Volantids meteor shower

    NASA Astrophysics Data System (ADS)

    Younger, J.; Reid, I.; Murphy, D.

    2016-01-01

    A new meteor shower occurring for the first time on 31 December 2015 in the constellation Volans was identified by the CAMS meteor video network in New Zealand. Data from two VHF meteor radars located in Australia and Antarctica have been analyzed using the great circle method to search for Volantids activity. The new shower was found to be active for at least three days over the period 31 December 2015 - 2 January 2016, peaking at an apparent radiant of R.A. = 119.3 ± 3.7, dec. = -74.5 ± 1.9 on January 1st. Measurements of meteoroid velocity were made using the Fresnel transform technique, yielding a geocentric shower velocity of 28.1 ± 1.8 km s-1. The orbital parameters for the parent stream are estimated to be a = 2.11 AU, e = 0.568, i = 47.2°, with a perihelion distance of q = 0.970 AU.

  9. Rat models of prenatal and adolescent cannabis exposure.

    PubMed

    Dinieri, Jennifer A; Hurd, Yasmin L

    2012-01-01

    Marijuana (Cannabis sativa) is the illicit drug most commonly used by two vulnerable populations relevant to neurodevelopment-pregnant women and teenagers. Human longitudinal studies have linked prenatal and adolescent cannabis exposure with long-term behavioral abnormalities as well as increased vulnerability to neuropsychiatric disorders in adulthood. Animal models provide a means of studying the neurobiological mechanisms underlying these long-term effects. This chapter provides an overview of the animal models we have used to study the developmental impact of cannabis.

  10. Evaluating biomarkers to model cancer risk post cosmic ray exposure

    NASA Astrophysics Data System (ADS)

    Sridharan, Deepa M.; Asaithamby, Aroumougame; Blattnig, Steve R.; Costes, Sylvain V.; Doetsch, Paul W.; Dynan, William S.; Hahnfeldt, Philip; Hlatky, Lynn; Kidane, Yared; Kronenberg, Amy; Naidu, Mamta D.; Peterson, Leif E.; Plante, Ianik; Ponomarev, Artem L.; Saha, Janapriya; Snijders, Antoine M.; Srinivasan, Kalayarasan; Tang, Jonathan; Werner, Erica; Pluth, Janice M.

    2016-06-01

    Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome aberrations, reactive oxygen species and telomere length changes. We discuss the relationship of biomarkers to different potential cell fates, including proliferation, apoptosis, senescence, and loss of stemness, which can propagate genomic instability and alter tissue composition and the underlying mRNA signatures that contribute to cell fate decisions. Our goal is to highlight factors that are important in choosing

  11. Evaluating biomarkers to model cancer risk post cosmic ray exposure.

    PubMed

    Sridharan, Deepa M; Asaithamby, Aroumougame; Blattnig, Steve R; Costes, Sylvain V; Doetsch, Paul W; Dynan, William S; Hahnfeldt, Philip; Hlatky, Lynn; Kidane, Yared; Kronenberg, Amy; Naidu, Mamta D; Peterson, Leif E; Plante, Ianik; Ponomarev, Artem L; Saha, Janapriya; Snijders, Antoine M; Srinivasan, Kalayarasan; Tang, Jonathan; Werner, Erica; Pluth, Janice M

    2016-06-01

    Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome aberrations, reactive oxygen species and telomere length changes. We discuss the relationship of biomarkers to different potential cell fates, including proliferation, apoptosis, senescence, and loss of stemness, which can propagate genomic instability and alter tissue composition and the underlying mRNA signatures that contribute to cell fate decisions. Our goal is to highlight factors that are important in choosing

  12. Evaluating biomarkers to model cancer risk post cosmic ray exposure.

    PubMed

    Sridharan, Deepa M; Asaithamby, Aroumougame; Blattnig, Steve R; Costes, Sylvain V; Doetsch, Paul W; Dynan, William S; Hahnfeldt, Philip; Hlatky, Lynn; Kidane, Yared; Kronenberg, Amy; Naidu, Mamta D; Peterson, Leif E; Plante, Ianik; Ponomarev, Artem L; Saha, Janapriya; Snijders, Antoine M; Srinivasan, Kalayarasan; Tang, Jonathan; Werner, Erica; Pluth, Janice M

    2016-06-01

    Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome aberrations, reactive oxygen species and telomere length changes. We discuss the relationship of biomarkers to different potential cell fates, including proliferation, apoptosis, senescence, and loss of stemness, which can propagate genomic instability and alter tissue composition and the underlying mRNA signatures that contribute to cell fate decisions. Our goal is to highlight factors that are important in choosing

  13. ASSESSING A COMPUTER MODEL FOR PREDICTING HUMAN EXPOSURE TO PM2.5

    EPA Science Inventory

    This paper compares outputs of a model for predicting PM2.5 exposure with experimental data obtained from exposure studies of selected subpopulations. The exposure model is built on a WWW platform called pCNEM, "A PC Version of pNEM." Exposure models created by pCNEM are sim...

  14. Influence of the Landau-Pomeranchuk-Migdal effect on the features of extensive air showers

    SciTech Connect

    Kalmykov, N.N.; Ostapchenko, S.S.; Pavlov, A.I.

    1995-10-01

    The influence of the Landau-Pomeranchuk-Migdal (LPM) effect on the features of extensive air showers (EAS) is studied. The development of hadronic cascades is described in the quark-gluon string model. It is shown that the LPM effect does not exert a significant influence on EAS features up to energies of 10{sup 20} eV. 19 refs., 2 figs.

  15. Composition studies based on coincident air shower array and underground muon data

    SciTech Connect

    DasGupta, U.; Ruddick, K. ); Fields, T.H. )

    1991-08-01

    We report on a final analysis of coincident underground muon data measured by the Soudan 1 proton decay detector and air shower data measured by an associated proportional tube array. These data were reported first at the 21st ICRC, Adelaide. We have done further analysis to determine the principal sources of systematic errors in such measurements, including different models of the primary interaction.

  16. MODELING HUMAN EXPOSURES AND DOSE USING A 2-DIMENSIONAL MONTE-CARLO MODEL (SHEDS)

    EPA Science Inventory

    Since 1998, US EPA's National Exposure Research Laboratory (NERL) has been developing the Stochastic Human Exposure and Dose Simulation (SHEDS) model for various classes of pollutants. SHEDS is a physically-based probabilistic model intended for improving estimates of human ex...

  17. Study and models of total lead exposures of battery workers.

    PubMed

    Chavalitnitikul, C; Levin, L; Chen, L C

    1984-12-01

    In an attempt to establish a more realistic and reliable model for relating environmental exposure measurements to the biological indices of exposure, a study was undertaken to quantify the total sources of lead exposure among lead storage battery workers. In addition to the usual personal and area lead air sampling, quantitative and repeatable measurements of removable lead from work surfaces and the workers' hands and faces were obtained daily for ten consecutive work days in the pasting and battery assembly departments. Mathematical correlations of blood lead and zinc protoporphyrin (ZPP) levels as the dependent variable with the lead exposure sources were derived and demonstrated most strongly as log-log relationships. Statistical analyses by computer programming indicated that the airborne, hand, facial and work surface levels have a high degree of inter-correlation with a very significant positive individual correlation with blood lead levels and a somewhat lower correlation with ZPP. The results suggest that contaminated personal and work surfaces may play a more significant role in toxic occupational and environmental exposures, generally, than had heretofore been demonstrated or suspected. PMID:6517025

  18. Imaging pion showers with the CALICE analogue hadron calorimeter

    SciTech Connect

    Feege, N.

    2011-07-01

    The CALICE collaboration investigates different technology options for highly granular calorimeters for detectors at a future electron-positron collider. One of the devices constructed and tested by the collaboration is a 1 m{sup 3} prototype for an imaging scintillator-steel sampling calorimeter for hadrons with analogue readout (AHCAL). The light from 7608 small scintillator cells is detected with silicon photomultipliers. The AHCAL has been successfully operated during electron and hadron test-beam measurements at DESY, CERN, and Fermilab since 2005. The collected data allow for evaluating the novel technologies employed. In addition, these data provide a valuable basis for validating pion cascade simulations. This paper presents the current status of comparisons between the AHCAL data and predictions from different Monte Carlo models implemented in GEANT4. The comparisons cover the total visible energy, longitudinal and radial shower profiles, and the shower substructure. Furthermore, this paper discusses a software compensation algorithm for improving the energy resolution of the AHCAL for single pions. (authors)

  19. Depth Distribution Of The Maxima Of Extensive Air Shower

    NASA Technical Reports Server (NTRS)

    Adams, J. H.; Howell, L. W.

    2003-01-01

    Observations of the extensive air showers from space can be free from interference by low altitude clouds and aerosols if the showers develop at a sufficiently high altitude. In this paper we explore the altitude distribution of shower maxima to determine the fraction of all showers that will reach their maxima at sufficient altitudes to avoid interference from these lower atmosphere phenomena. Typically the aerosols are confined within a planetary boundary layer that extends from only 2-3 km above the Earth's surface. Cloud top altitudes extend above 15 km but most are below 4 km. The results reported here show that more than 75% of the showers that will be observed by EUSO have maxima above the planetary boundary layer. The results also show that more than 50% of the showers that occur on cloudy days have their maxima above the cloud tops.

  20. An Evaluation of the Accuracy of Meteor Shower Forecasts

    NASA Technical Reports Server (NTRS)

    Cooke, W.; Moser, D.

    2004-01-01

    Brought into being by the recent Leonid meteor storms, meteor shower forecasts are now regarded by many spacecraft projects as necessary inputs into the planning of spacecraft operations. We compare the shower forecasts made by various researchers over the past six years to actual shower observations in an attempt to create an overall picture of forecast accuracy, specifically focusing on the three aspects most important to space vehicles: 1) the time of shower maximum, 2) the half-width (duration), and 3) the maximum Zenith Hourly Rate (ZHR). It will be noted that, while the times of maxima are generally predicted to within several minutes, the peak ZHRs are often overestimated and shower half-widths are frequently not even calculated. The difficulties involved in converting shower ZHRs into the meteoroid fluxes needed to assess spacecraft risk are also discussed.

  1. Using transportation demand models to assess regional noise exposure

    NASA Astrophysics Data System (ADS)

    Kaliski, Kenneth

    2005-09-01

    In the United States, most metropolitan areas run some type of transportation demand model to estimate regional travel patterns, and, to some extent, air pollution. The more advanced of these models accurately represent the geographic contours of the roadways (in contrast to the older straight-line node and link models). This allows an almost seamless integration of these new transportation demand models into noise prediction models. Combined with the locations of individual homes from a separate E911 database, we can readily make estimates of the noise exposure of populations over large areas. In this paper, the regional traffic noise exposure of residences of Chittenden County, VT is estimated and mapped. It was found that 30% of the residences are exposed to noise levels exceeding the WHO sleep disturbance level of 45 dB LAeq(8) and 20% of residences are exposed to levels exceeding the WHO ``serious annoyance'' level of 55 dB LAeq(16). Maps show noise contours as well as individual homes color coded based on relative day and night noise exposure levels. Measured sound level data are given for particular locations to validate the predictions.

  2. OVERVIEW OF THE U.S. EPA NERL'S HUMAN EXPOSURE MODELING

    EPA Science Inventory

    Computational modeling of human exposure to environmental pollutants is one of the primary activities of the US Environmental Protection Agency's National Exposure Research Laboratory (NERL). Assessment of human exposures is a critical part of the overall risk assessment para...

  3. Exposure Modeling of Residential Infiltration of Black Carbon for NEXUS Participants

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using outdoor concentrations. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improve ex...

  4. USE OF EXPOSURE-RELATED DOSE ESTIMATING MODEL (ERDEM) FOR ASSESSMENT OF AGGREGATE EXPOSURE OF INFANT AND CHILDREN TO N-METHYL CARBAMATE INSECTICIDES

    EPA Science Inventory

    A physiologically based pharmacokinetic (PBPK) model was developed within the Exposure Related Dose Estimating Model (ERDEM) framework to investigate selected exposure inputs related to recognized exposure scenarios of infants and children to N-methyl carbamate pesticides as spec...

  5. MODELING ENERGY EXPENDITURE AND OXYGEN CONSUMPTION IN HUMAN EXPOSURE MODELS: ACCOUNTING FOR FATIGUE AND EPOC

    EPA Science Inventory

    Human exposure and dose models often require a quantification of oxygen consumption for a simulated individual. Oxygen consumption is dependent on the modeled Individual's physical activity level as described in an activity diary. Activity level is quantified via standardized val...

  6. Modeling flight attendants' exposures to pesticide in disinsected aircraft cabins.

    PubMed

    Zhang, Yong; Isukapalli, Sastry; Georgopoulos, Panos; Weisel, Clifford

    2013-12-17

    Aircraft cabin disinsection is required by some countries to kill insects that may pose risks to public health and native ecological systems. A probabilistic model has been developed by considering the microenvironmental dynamics of the pesticide in conjunction with the activity patterns of flight attendants, to assess their exposures and risks to pesticide in disinsected aircraft cabins under three scenarios of pesticide application. Main processes considered in the model are microenvironmental transport and deposition, volatilization, and transfer of pesticide when passengers and flight attendants come in contact with the cabin surfaces. The simulated pesticide airborne mass concentration and surface mass loadings captured measured ranges reported in the literature. The medians (means ± standard devitions) of daily total exposure intakes were 0.24 (3.8 ± 10.0), 1.4 (4.2 ± 5.7), and 0.15 (2.1 ± 3.2) μg day(-1) kg(-1) of body weight for scenarios of residual application, preflight, and top-of-descent spraying, respectively. Exposure estimates were sensitive to parameters corresponding to pesticide deposition, body surface area and weight, surface-to-body transfer efficiencies, and efficiency of adherence to skin. Preflight spray posed 2.0 and 3.1 times higher pesticide exposure risk levels for flight attendants in disinsected aircraft cabins than top-of-descent spray and residual application, respectively.

  7. Adapted cold shower as a potential treatment for depression.

    PubMed

    Shevchuk, Nikolai A

    2008-01-01

    Depression is a debilitating mood disorder that is among the top causes of disability worldwide. It can be characterized by a set of somatic, emotional, and behavioral symptoms, one of which is a high risk of suicide. This work presents a hypothesis that depression may be caused by the convergence of two factors: (A) A lifestyle that lacks certain physiological stressors that have been experienced by primates through millions of years of evolution, such as brief changes in body temperature (e.g. cold swim), and this lack of "thermal exercise" may cause inadequate functioning of the brain. (B) Genetic makeup that predisposes an individual to be affected by the above condition more seriously than other people. To test the hypothesis, an approach to treating depression is proposed that consists of adapted cold showers (20 degrees C, 2-3 min, preceded by a 5-min gradual adaptation to make the procedure less shocking) performed once or twice daily. The proposed duration of treatment is several weeks to several months. The following evidence appears to support the hypothesis: Exposure to cold is known to activate the sympathetic nervous system and increase the blood level of beta-endorphin and noradrenaline and to increase synaptic release of noradrenaline in the brain as well. Additionally, due to the high density of cold receptors in the skin, a cold shower is expected to send an overwhelming amount of electrical impulses from peripheral nerve endings to the brain, which could result in an anti-depressive effect. Practical testing by a statistically insignificant number of people, who did not have sufficient symptoms to be diagnosed with depression, showed that the cold hydrotherapy can relieve depressive symptoms rather effectively. The therapy was also found to have a significant analgesic effect and it does not appear to have noticeable side effects or cause dependence. In conclusion, wider and more rigorous studies would be needed to test the validity of the

  8. Inhalation Exposure Input Parameters for the Biosphere Model

    SciTech Connect

    M. Wasiolek

    2006-06-05

    This analysis is one of the technical reports that support the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN), referred to in this report as the biosphere model. ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes in detail the conceptual model as well as the mathematical model and its input parameters. This report documents development of input parameters for the biosphere model that are related to atmospheric mass loading and supports the use of the model to develop biosphere dose conversion factors (BDCFs). The biosphere model is one of a series of process models supporting the total system performance assessment (TSPA) for a Yucca Mountain repository. ''Inhalation Exposure Input Parameters for the Biosphere Model'' is one of five reports that develop input parameters for the biosphere model. A graphical representation of the documentation hierarchy for the biosphere model is presented in Figure 1-1 (based on BSC 2006 [DIRS 176938]). This figure shows the interrelationships among the products (i.e., analysis and model reports) developed for biosphere modeling and how this analysis report contributes to biosphere modeling. This analysis report defines and justifies values of atmospheric mass loading for the biosphere model. Mass loading is the total mass concentration of resuspended particles (e.g., dust, ash) in a volume of air. Mass loading values are used in the air submodel of the biosphere model to calculate concentrations of radionuclides in air inhaled by a receptor and concentrations in air surrounding crops. Concentrations in air to which the receptor is exposed are then used in the inhalation submodel to calculate the dose contribution to the receptor from inhalation of contaminated airborne particles. Concentrations in air surrounding plants are used in the plant submodel to calculate the concentrations of radionuclides in foodstuffs contributed from uptake by foliar interception. This report is concerned primarily with the

  9. Measurement of the muon content in air showers at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Veberič, Darko

    2016-07-01

    The muon content of extensive air showers produced by ultra-high energy cosmic rays is an observable sensitive to the composition of primary particles and to the properties of hadronic interactions governing the evolution of air-shower cascades. We present different methods for estimation of the number of muons at the ground and the muon production depth. These methods use measurements of the longitudinal, lateral, and temporal distribution of particles in air showers recorded by the detectors of the Pierre Auger Observatory. The results, obtained at about 140 TeV center-of-mass energy for proton primaries, are compared to the predictions of LHC-tuned hadronic-interaction models used in simulations with different primary masses. The models exhibit a deficitin the predicted muon content. The combination of these results with other independent mass composition analyses, such as those involving the depth of shower maximum observablemax, provide additional constraints on hadronic-interaction models for energies beyond the reach of the LHC.

  10. Model simulation of atrazine exposure to aquatic nontarget organisms

    SciTech Connect

    Williams, W.M.; Cheplick, J.M.; Balu, K.

    1996-10-01

    Pesticide fate and transport models have been identified by a number of regulatory work groups, including the Aquatic Risk Assessment and Mitigation Dialogue Group (ARAMDG) and the FIFRA Exposure Modeling Work Group (EMWG), as potential valuable tools in improving regulatory decisions for pesticide registration. To date, models uses have been limited to preliminary screening evaluations because the predictive capabilities of candidate models have not been adequately characterized and because procedures for scenario identification have not been tested. This paper presents an overview of a comprehensive modeling study that was conducted to evaluate exposure concentrations of atrazine to nontarget organisms and their ecosystems that may result from usage patterns of the herbicide throughout the United States. Simulations were conducted using the Pesticide Root Zone Model (PRZM-2.3) and the Riverine Environments Water Quality Model (RIVWQ-2.0). Included are procedures used for scenario identification, model comparisons to field runoff and aquatic monitoring studies, and the statistical compilation of results for risk assessment use.

  11. Modelling of radiation exposure at high altitudes during solar storms.

    PubMed

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

    2009-10-01

    A transport code analysis using Monte Carlo N-Particle eXtended code, MCNPX, has been used to propagate an extrapolated particle spectrum based on satellite measurements through the atmosphere to estimate radiation exposure during solar storms at high altitudes. Neutron monitor count rate data from stations around the world were used to benchmark the model calculations during a ground-level event (GLE). A comparison was made between the model predictions and actual flight measurements taken with various types of instruments used to measure the mixed radiation field during GLE 60. A computer code has been developed to implement the model for routine analysis.

  12. Design, development, and operation of a zero gravity shower

    NASA Technical Reports Server (NTRS)

    Middleton, R. L.; Krupnick, A. C.; Reily, J. C.; Schrick, B. J.

    1974-01-01

    The high mission penalty associated with water and electrical power usage constrained the shower configuration concept for the Skylab project to a procedure in which water is sprayed on the body to wet down and soaping is accomplished without water flow. The soap is then finally rinsed off. Initial concept confirmation tests are discussed along with details of the flight shower configuration, the shower water bottle, the shower stall assembly, the liquid-gas separator, the collection box and bag assembly, the hydrophobic filter assembly, and the soap dispenser. Aspects of microbial evaluation of flight qualification hardware are also considered.

  13. ISSUES AND CHALLENGES IN MODELING CHILDREN'S LONGITUDINAL EXPOSURES: AN OZONE STUDY

    EPA Science Inventory

    Modeling children's exposures is a complicated, data-intensive process. Modeling longitudinal exposures, which are important for regulatory decision making, especially for most air toxics, adds another level of complexity and data requirements. Because it is difficult to model in...

  14. High Throughput Exposure Prioritization of Chemicals Using a Screening-Level Probabilistic SHEDS-Lite Exposure Model

    EPA Science Inventory

    These novel modeling approaches for screening, evaluating and classifying chemicals based on the potential for biologically-relevant human exposures will inform toxicity testing and prioritization for chemical risk assessment. The new modeling approach is derived from the Stocha...

  15. Air pollution dispersion models for human exposure predictions in London.

    PubMed

    Beevers, Sean D; Kitwiroon, Nutthida; Williams, Martin L; Kelly, Frank J; Ross Anderson, H; Carslaw, David C

    2013-01-01

    The London household survey has shown that people travel and are exposed to air pollutants differently. This argues for human exposure to be based upon space-time-activity data and spatio-temporal air quality predictions. For the latter, we have demonstrated the role that dispersion models can play by using two complimentary models, KCLurban, which gives source apportionment information, and Community Multi-scale Air Quality Model (CMAQ)-urban, which predicts hourly air quality. The KCLurban model is in close agreement with observations of NO(X), NO(2) and particulate matter (PM)(10/2.5), having a small normalised mean bias (-6% to 4%) and a large Index of Agreement (0.71-0.88). The temporal trends of NO(X) from the CMAQ-urban model are also in reasonable agreement with observations. Spatially, NO(2) predictions show that within 10's of metres of major roads, concentrations can range from approximately 10-20 p.p.b. up to 70 p.p.b. and that for PM(10/2.5) central London roadside concentrations are approximately double the suburban background concentrations. Exposure to different PM sources is important and we predict that brake wear-related PM(10) concentrations are approximately eight times greater near major roads than at suburban background locations. Temporally, we have shown that average NO(X) concentrations close to roads can range by a factor of approximately six between the early morning minimum and morning rush hour maximum periods. These results present strong arguments for the hybrid exposure model under development at King's and, in future, for in-building models and a model for the London Underground.

  16. Mobile phone model with metamaterials to reduce the exposure

    NASA Astrophysics Data System (ADS)

    Pinto, Yenny; Begaud, Xavier

    2016-04-01

    This work presents a terminal mobile model where an Inverted-F Antenna (IFA) is associated with three different kinds of metamaterials: artificial magnetic conductor (AMC), electromagnetic band gap (EBG) and resistive high-impedance surface (RHIS). The objective was to evaluate whether some metamaterials may be used to reduce exposure while preserving the antenna performances. The exposure has been evaluated using a simplified phantom model. Two configurations, antenna in front of the phantom and antenna hidden by the ground plane, have been evaluated. Results show that using an optimized RHIS, the SAR 10 g is reduced and the antenna performances are preserved. With RHIS solution, the SAR 10 g peak is reduced by 8 % when the antenna is located in front of the phantom and by 6 % when the antenna is hidden by ground plane.

  17. Biology Based Lung Cancer Model for Chronic Low Radon Exposures

    NASA Astrophysics Data System (ADS)

    TruÅ£ǎ-Popa, Lucia-Adina; Hofmann, Werner; Fakir, Hatim; Cosma, Constantin

    2008-08-01

    Low dose effects of alpha particles at the tissue level are characterized by the interaction of single alpha particles, affecting only a small fraction of the cells within that tissue. Alpha particle intersections of bronchial target cells during a given exposure period were simulated by an initiation-promotion model, formulated in terms of cellular hits within the cycle time of the cell (dose-rate) and then integrated over the whole exposure period (dose). For a given average number of cellular hits during the lifetime of bronchial cells, the actual number of single and multiple hits was selected from a Poisson distribution. While oncogenic transformation is interpreted as the primary initiation step, stimulated mitosis by killing adjacent cells is assumed to be the primary radiological promotion event. Analytical initiation and promotion functions were derived from experimental in vitro data on oncogenic transformation and cellular survival. To investigate the shape of the lung cancer risk function at chronic, low level exposures in more detail, additional biological factors describing the tissue response and operating specifically at low doses were incorporated into the initiation-promotion model. These mechanisms modifying the initial response at the cellular level were: adaptive response, genomic instability, induction of apoptosis by surrounding cells, and detrimental as well as protective bystander mechanisms. To quantify the effects of these mechanisms as functions of dose, analytical functions were derived from the experimental evidence presently available. Predictions of lung cancer risk, including these mechanisms, exhibit a distinct sublinear dose-response relationship at low exposures, particularly for very low exposure rates.

  18. Biology Based Lung Cancer Model for Chronic Low Radon Exposures

    SciTech Connect

    Truta-Popa, Lucia-Adina; Hofmann, Werner; Fakir, Hatim; Cosma, Constantin

    2008-08-07

    Low dose effects of alpha particles at the tissue level are characterized by the interaction of single alpha particles, affecting only a small fraction of the cells within that tissue. Alpha particle intersections of bronchial target cells during a given exposure period were simulated by an initiation-promotion model, formulated in terms of cellular hits within the cycle time of the cell (dose-rate) and then integrated over the whole exposure period (dose). For a given average number of cellular hits during the lifetime of bronchial cells, the actual number of single and multiple hits was selected from a Poisson distribution. While oncogenic transformation is interpreted as the primary initiation step, stimulated mitosis by killing adjacent cells is assumed to be the primary radiological promotion event. Analytical initiation and promotion functions were derived from experimental in vitro data on oncogenic transformation and cellular survival.To investigate the shape of the lung cancer risk function at chronic, low level exposures in more detail, additional biological factors describing the tissue response and operating specifically at low doses were incorporated into the initiation-promotion model. These mechanisms modifying the initial response at the cellular level were: adaptive response, genomic instability, induction of apoptosis by surrounding cells, and detrimental as well as protective bystander mechanisms. To quantify the effects of these mechanisms as functions of dose, analytical functions were derived from the experimental evidence presently available. Predictions of lung cancer risk, including these mechanisms, exhibit a distinct sublinear dose-response relationship at low exposures, particularly for very low exposure rates.

  19. Modelling of aircrew radiation exposure during solar particle events

    NASA Astrophysics Data System (ADS)

    Al Anid, Hani Khaled

    show a very different response during anisotropic events, leading to variations in aircrew radiation doses that may be significant for dose assessment. To estimate the additional exposure due to solar flares, a model was developed using a Monte-Carlo radiation transport code, MCNPX. The model transports an extrapolated particle spectrum based on satellite measurements through the atmosphere using the MCNPX analysis. This code produces the estimated flux at a specific altitude where radiation dose conversion coefficients are applied to convert the particle flux into effective and ambient dose-equivalent rates. A cut-off rigidity model accounts for the shielding effects of the Earth's magnetic field. Comparisons were made between the model predictions and actual flight measurements taken with various types of instruments used to measure the mixed radiation field during Ground Level Enhancements 60 and 65. An anisotropy analysis that uses neutron monitor responses and the pitch angle distribution of energetic solar particles was used to identify particle anisotropy for a solar event in December 2006. In anticipation of future commercial use, a computer code has been developed to implement the radiation dose assessment model for routine analysis. Keywords: Radiation Dosimetry, Radiation Protection, Space Physics.

  20. Probing Atmospheric Electric Fields through Radio Emission from Cosmic-Ray-Induced Air Showers

    NASA Astrophysics Data System (ADS)

    Scholten, Olaf; Trinh, Gia; Buitink, Stijn; Corstanje, Arthur; Ebert, Ute; Enriquez, Emilio; Falcke, Heino; Hoerandel, Joerg; Nelles, Anna; Schellart, Pim; Rachen, Joerg; Rutjes, Casper; ter Veen, Sander; Rossetto, Laura; Thoudam, Satyendra

    2016-04-01

    Energetic cosmic rays impinging on the atmosphere create a particle avalanche called an extensive air shower. In the leading plasma of this shower electric currents are induced that generate coherent radio wave emission that has been detected with LOFAR, a large and dense array of simple radio antennas primarily developed for radio-astronomy observations. Our measurements are performed in the 30-80 MHz frequency band. For fair weather conditions the observations are in excellent agreement with model calculations. However, for air showers measured under thunderstorm conditions we observe large differences in the intensity and polarization patterns from the predictions of fair weather models. We will show that the linear as well as the circular polarization of the radio waves carry clear information on the magnitude and orientation of the electric fields at different heights in the thunderstorm clouds. We will show that from the measured data at LOFAR the thunderstorm electric fields can be reconstructed. We thus have established the measurement of radio emission from extensive air showers induced by cosmic rays as a new tool to probe the atmospheric electric fields present in thunderclouds in a non-intrusive way. In part this presentation is based on the work: P. Schellart et al., Phys. Rev. Lett. 114, 165001 (2015).

  1. A New Model for Environmental Assessment and Exposure Reduction

    PubMed Central

    Ciaccio, Christina E.; Kennedy, Kevin; Portnoy, Jay M.

    2012-01-01

    Environmental assessment and exposure reduction are a set of diagnostic and treatment techniques that work in tandem with the traditional medical approach by reducing a patient’s exposure to adverse environmental conditions as part of medical care. Assessment involves identifying the specific exposures to which a patient is sensitive and locating the corresponding contaminants in the patient’s environment. This provides a more complete diagnostic evaluation of a patient’s problem than could be obtained merely by examining the patient alone. Exposure reduction involves reducing the identified triggers to levels that are below thresholds that are associated with increased risk of sensitization and disease morbidity. Assessment of an environment for contaminants focuses on a chain of factors that include contaminant sources such as cockroaches, rodents, dust mites and fungi that excrete contaminants into an environment, facilitative factors such as moisture, food, water and shelter that help sources to thrive, and reservoirs where contaminants can accumulate prior to subsequent transport to occupants. By using this model to guide environmental assessments and their corresponding interventions, the root cause of health problems can be addressed, leading to improved quality of life for patients and reduced need for chronic medications. PMID:22933137

  2. The thickness of the shower disc as observed in showers produced by primaries above 10 (19)eV

    NASA Technical Reports Server (NTRS)

    Lawrence, M. A.; Watson, A. A.; West, A. A.

    1985-01-01

    The thickness of the shower disk has been measured in showers initiated by primaries of energy to 10 the 19th power eV using the large area water Cerenkov detectors of the Haverah Park array. Results are presented which (1) provide supporting evidence for the accuracy of analysis procedures in giant showers, (2) offer an evaluation of the mini-array technique for the detection of giant showers and (3) extend earlier work on developmental fluctuations above 10 to the 19th power eV.

  3. POPULATION EXPOSURE AND DOSE MODEL FOR AIR TOXICS: A BENZENE CASE STUDY

    EPA Science Inventory

    The EPA's National Exposure Research Laboratory (NERL) is developing a human exposure and dose model called the Stochastic Human Exposure and Dose Simulation model for Air Toxics (SHEDS-AirToxics) to characterize population exposure to air toxics in support of the National Air ...

  4. Stratospheric Sampling and In Situ Atmospheric Chemical Element Analysis During Meteor Showers: A Resource Study

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    2000-01-01

    Resources studies for asteroidal mining evaluation have depended historically on remote sensing analysis for chemical elements. During the November 1998 Leonids meteor shower, a stratospheric balloon and various low-density capture media were used to sample fragments from Comet Tempel-Tuttle debris during a peak Earth crossing. The analysis not only demonstrates how potential sampling strategies may improve the projections for metals or rare elements in astromining, but also benchmarks materials during low temperature (-60 F), high dessication environments as seen during atmospheric exposure. The results indicate high aluminum, magnesium and iron content for various sampled particles recovered, but generalization to the sporadic meteors expected from asteroidal sources will require future improvements in larger sampling volumes before a broad-use strategy for chemical analysis can be described. A repeat of the experimental procedure is planned for the November 1999 Leonids' shower, and various improvements for atmospheric sampling will be discussed.

  5. Surveys of Microwave Emission from Air Showers

    NASA Astrophysics Data System (ADS)

    Kuramoto, Kazuyuki; Ogio, Shoichi; Iijima, Takashi; Yamamoto, Tokonatsu

    2011-09-01

    A possibility of detection of microwave molecular bremsstrahlung radiation from Extensive Air Showers was reported by AMBER group [1] [2]. This method has a potential to provide a high duty cycle and a new technique for measuring longitudinal profile of EAS. To survey this microwave emission from EAS, we built prototype detectors using parabolic antenna dishes for broadcasting satellites, and we are operating detectors with a small EAS array at Osaka City Univercity. Here, we report our detector configurations and the current experimental status.

  6. The history of meteors and meteor showers

    NASA Astrophysics Data System (ADS)

    Hughes, David W.

    The history of meteors and meteor showers can effectively start with the work of Edmond Halley who overcome the Aristotelean view of meteors as being an upper atmospheric phenomenon and introduced their extraterrestrial nature. Halley also estimated their height and velocity. The observations of the Leonids in 1799, 1833 and 1866 established meteoroids as cometary debris. Two red herrings were caught — fixed radiants and hyperbolic velocities. But the 1890 to 1950 period with two-station meteor photography, meteor spectroscopy and the radar detection of meteors saw the subject well established.

  7. Identifiability of PBPK models with applications to dimethylarsinic acid exposure.

    PubMed

    Garcia, Ramon I; Ibrahim, Joseph G; Wambaugh, John F; Kenyon, Elaina M; Setzer, R Woodrow

    2015-12-01

    Any statistical model should be identifiable in order for estimates and tests using it to be meaningful. We consider statistical analysis of physiologically-based pharmacokinetic (PBPK) models in which parameters cannot be estimated precisely from available data, and discuss different types of identifiability that occur in PBPK models and give reasons why they occur. We particularly focus on how the mathematical structure of a PBPK model and lack of appropriate data can lead to statistical models in which it is impossible to estimate at least some parameters precisely. Methods are reviewed which can determine whether a purely linear PBPK model is globally identifiable. We propose a theorem which determines when identifiability at a set of finite and specific values of the mathematical PBPK model (global discete identifiability) implies identifiability of the statistical model. However, we are unable to establish conditions that imply global discrete identifiability, and conclude that the only safe approach to analysis of PBPK models involves Bayesian analysis with truncated priors. Finally, computational issues regarding posterior simulations of PBPK models are discussed. The methodology is very general and can be applied to numerous PBPK models which can be expressed as linear time-invariant systems. A real data set of a PBPK model for exposure to dimethyl arsinic acid (DMA(V)) is presented to illustrate the proposed methodology. PMID:26194069

  8. Geographical modeling of exposure risk to cyanobacteria for epidemiological purposes.

    PubMed

    Serrano, Tania; Dupas, Rémi; Upegui, Erika; Buscail, Camille; Grimaldi, Catherine; Viel, Jean François

    2015-08-01

    The cyanobacteria-derived neurotoxin β-methylamino-L-alanine (BMAA) represents a plausible environmental trigger for amyotrophic lateral sclerosis (ALS), a debilitating and fatal neuromuscular disease. With the eutrophication of water bodies, cyanobacterial blooms and their toxins are becoming increasingly prevalent in France, especially in the Brittany region. Cyanobacteria are monitored at only a few recreational sites, preventing an estimation of exposure of the human population. By contrast, phosphorus, a limiting nutrient for cyanobacterial growth and thus considered a good proxy for cyanobacteria exposure, is monitored in many but not all surface water bodies. Our goal was to develop a geographic exposure indicator that could be used in epidemiological research. We considered the total phosphorus (TP) concentration (mg/L) of samples collected between October 2007 and September 2012 at 179 monitoring stations distributed throughout the Brittany region. Using readily available spatial data, we computed environmental descriptors at the watershed level with a Geographic Information System. Then, these descriptors were introduced into a backward stepwise linear regression model to predict the median TP concentration in unmonitored surface water bodies. TP concentrations in surface water follow an increasing gradient from West to East and inland to coast. The empirical concentration model included five predictor variables with a fair coefficient of determination (R(2) = 0.51). The specific total runoff and the watershed slope correlated negatively with the TP concentrations (p = 0.01 and p< 10(-9), respectively), whereas positive associations were found for the proportion of built-up area, the upstream presence of sewage treatment plants, and the algae volume as indicated by the Landsat red/green reflectance ratio (p < 0.01, p < 10(-6) and p < 0.01, respectively). Complementing the monitoring networks, this geographical modeling can help estimate TP concentrations

  9. EXPOSURE RELATED DOSE ESTIMATING MODEL ( ERDEM ) A PHYSIOLOGICALLY-BASED PHARMACOKINETIC AND PHARMACODYNAMIC ( PBPK/PD ) MODEL FOR ASSESSING HUMAN EXPOSURE AND RISK

    EPA Science Inventory

    The Exposure Related Dose Estimating Model (ERDEM) is a PBPK/PD modeling system that was developed by EPA's National Exposure Research Laboratory (NERL). The ERDEM framework provides the flexibility either to use existing models and to build new PBPK and PBPK/PD models to address...

  10. The radio emission pattern of air showers as measured with LOFAR—a tool for the reconstruction of the energy and the shower maximum

    NASA Astrophysics Data System (ADS)

    Nelles, A.; Buitink, S.; Corstanje, A.; Enriquez, J. E.; Falcke, H.; Hörandel, J. R.; Rachen, J. P.; Rossetto, L.; Schellart, P.; Scholten, O.; ter Veen, S.; Thoudam, S.; Trinh, T. N. G.

    2015-05-01

    The pattern of the radio emission of air showers is finely sampled with the Low-Frequency ARray (LOFAR). A set of 382 measured air showers is used to test a fast, analytic parameterization of the distribution of pulse powers. Using this parameterization we are able to reconstruct the shower axis and give estimators for the energy of the air shower as well as the distance to the shower maximum.

  11. Predictive modeling of terrestrial radiation exposure from geologic materials

    NASA Astrophysics Data System (ADS)

    Haber, Daniel A.

    Aerial gamma ray surveys are an important tool for national security, scientific, and industrial interests in determining locations of both anthropogenic and natural sources of radioactivity. There is a relationship between radioactivity and geology and in the past this relationship has been used to predict geology from an aerial survey. The purpose of this project is to develop a method to predict the radiologic exposure rate of the geologic materials in an area by creating a model using geologic data, images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), geochemical data, and pre-existing low spatial resolution aerial surveys from the National Uranium Resource Evaluation (NURE) Survey. Using these data, geospatial areas, referred to as background radiation units, homogenous in terms of K, U, and Th are defined and the gamma ray exposure rate is predicted. The prediction is compared to data collected via detailed aerial survey by our partner National Security Technologies, LLC (NSTec), allowing for the refinement of the technique. High resolution radiation exposure rate models have been developed for two study areas in Southern Nevada that include the alluvium on the western shore of Lake Mohave, and Government Wash north of Lake Mead; both of these areas are arid with little soil moisture and vegetation. We determined that by using geologic units to define radiation background units of exposed bedrock and ASTER visualizations to subdivide radiation background units of alluvium, regions of homogeneous geochemistry can be defined allowing for the exposure rate to be predicted. Soil and rock samples have been collected at Government Wash and Lake Mohave as well as a third site near Cameron, Arizona. K, U, and Th concentrations of these samples have been determined using inductively coupled mass spectrometry (ICP-MS) and laboratory counting using radiation detection equipment. In addition, many sample locations also have

  12. Fractal dimension of particle showers measured in a highly granular calorimeter.

    PubMed

    Ruan, Manqi; Jeans, Daniel; Boudry, Vincent; Brient, Jean-Claude; Videau, Henri

    2014-01-10

    We explore the fractal nature of particle showers using Monte Carlo simulation. We define the fractal dimension of showers measured in a high granularity calorimeter designed for a future lepton collider. The shower fractal dimension reveals detailed information of the spatial configuration of the shower. It is found to be characteristic of the type of interaction and highly sensitive to the nature of the incident particle. Using the shower fractal dimension, we demonstrate a particle identification algorithm that can efficiently separate electromagnetic showers, hadronic showers, and nonshowering tracks. We also find a logarithmic dependence of the shower fractal dimension on the particle energy.

  13. Circular polarization of radio emission from air showers probes atmospheric electric fields in thunderclouds.

    NASA Astrophysics Data System (ADS)

    Gia Trinh, Thi Ngoc; Scholten, Olaf; Buitink, Stijn; Corstanje, Arthur; Ebert, Ute; Enriquez, Emilio; Falcke, Heino; Horandel, Jörg R.; Nelles, Anna; Schellart, Pim; Rachen, Jorg; Rossetto, Laura; Rutjes, Casper; ter Veen, Sander; Thoudam, Satyendra

    2016-04-01

    When a high-energy cosmic-ray particle enters the upper layer of the atmosphere, it generates many secondary high-energy particles and forms a cosmic-ray-induced air shower. In the leading plasma of this shower electric currents are induced that emit electromagnetic radiation. These radio waves can be detected with LOw-Frequency ARray (LOFAR) radio telescope. Events have been collected under fair-weather conditions as well as under atmospheric conditions where thunderstorms occur. For the events under the fair weather conditions the emission process is well understood by present models. For the events measured under the thunderstorm conditions, we observe a large fraction of the circular polarization near the core of the shower which is not shown in the events under the fair-weather conditions. This can be explained by the change of direction of the atmospheric electric fields with altitude. Therefore, measuring the circular polarization of radio emission from cosmic ray extensive air showers during the thunderstorm conditions helps to have a better understanding about the structure of atmospheric electric fields in the thunderclouds.

  14. Meteor shower forecast improvements from a survey of all-sky network observations

    NASA Astrophysics Data System (ADS)

    Moorhead, Althea V.; Sugar, Glenn; Brown, Peter G.; Cooke, William J.

    2015-11-01

    Meteoroid impacts are capable of damaging spacecraft and potentially ending missions. In order to help spacecraft programs mitigate these risks, NASA’s Meteoroid Environment Office (MEO) monitors and predicts meteoroid activity. Temporal variations in near-Earth space are described by the MEO’s annual meteor shower forecast, which is based on both past shower activity and model predictions.The MEO and the University of Western Ontario operate sister networks of all-sky meteor cameras. These networks have been in operation for more than 7 years and have computed more than 20,000 meteor orbits. Using these data, we conduct a survey of meteor shower activity in the “fireball” size regime using DBSCAN. For each shower detected in our survey, we compute the date of peak activity and characterize the growth and decay of the shower’s activity before and after the peak. These parameters are then incorporated into the annual forecast for an improved treatment of annual activity.

  15. High Throughput Modeling of Indoor Exposures to Chemicals (SOT)

    EPA Science Inventory

    Risk due to chemical exposure is a function of both chemical hazard and exposure. Proximate sources of exposure due to the presence of a chemical in consumer products (i.e. near-field exposure) are identified as key drivers of exposure and yet are not well quantified or understo...

  16. Don Quixote - a possible parent body of a meteor shower

    NASA Astrophysics Data System (ADS)

    Rudawska, Regina; Vaubaillon, Jérémie

    2014-02-01

    Here we are interested in whether the meteoroid stream of (3552) Don Quixote can generate some observed meteor showers. We have showed that particles originating from Don Quixote particles produce two meteor showers at Earth: Kappa Lyrids and August Mu Draconids.

  17. The development of air shower in the iron absorber

    NASA Technical Reports Server (NTRS)

    Hazama, M.; Dake, S.; Harada, K.; Kawamoto, M.; Sakata, M.; Yamamoto, Y.; Sugihara, T.

    1985-01-01

    The iron open-sandwich experiments to observe one dimensional development of individual air showers were carried out at Akeno Observatory. One dimensional energy flow, incident energy and production height of shower is estimated using the data of size and age obtained from the above experiment and simple calculation.

  18. AIR TOXICS EMISSIONS FROM A VINYL SHOWER CURTAIN

    EPA Science Inventory

    The paper reports results of both static and dynamic chamber tests conducted to evaluate emission characteristics of air toxics from a vinyl shower Curtain. (NOTE: Due to the relatively low price and ease of installation, vinyl shower curtains have been widely used in bathrooms i...

  19. VIEW OF MASTER BATHROOM SHOWING TYPICAL SHOWER, STORAGE CABINETS BEHIND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF MASTER BATHROOM SHOWING TYPICAL SHOWER, STORAGE CABINETS BEHIND SHOWER, AND LAVATORY. VIEW FACING WEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Three-Bedroom Single-Family Type 9, Birch Circle, Elm Drive, Elm Circle, and Date Drive, Pearl City, Honolulu County, HI

  20. New shower maximum trigger for electrons and photons at CDF

    SciTech Connect

    Amidei, D.; Burkett, K.; Gerdes, D.; Miao, C.; Wolinski, D.; Byrum, K.; Dawson, J.; Nodulman, L.; Wicklund, A.B.

    1994-07-28

    For the 1994 Tevatron collider run, CDF has upgraded the electron and photo trigger hardware to make use of shower position and size information from the central shower maximum detector. For electrons, the upgrade has resulted in a 50% reduction in backgrounds while retaining approximately 90% of the signal. The new trigger also eliminates the background to photon triggers from single-phototube spikes.

  1. Meteor Showers of the Earth-crossing Asteroids

    NASA Astrophysics Data System (ADS)

    Pulat, Babadzhanov; Gulchekhra, Kokhirova

    2015-03-01

    The results of search for meteor showers associated with the asteroids crossing the Earthfs orbit and moving on comet-like orbits are given. It was shown that among 2872 asteroids discovered till 1.01.2005 and belonging to the Apollo and Amor groups, 130 asteroids have associated meteor showers and, therefore, are the extinct cometary nuclei.

  2. Measure Guideline. Water Management at Tub and Shower Assemblies

    SciTech Connect

    Dickson, Bruce

    2011-12-01

    Due to the high concentrations of water and the consequential risk of water damage to the home’s structure a comprehensive water management system is imperative to protect the building assemblies underlying the finish surround of tub and shower areas. This guide shows how to install fundamental waterproofing strategies to prevent water related issues at shower and tub areas.

  3. On sampling fractions and electron shower shapes

    SciTech Connect

    Peryshkin, Alexander; Raja, Rajendran; /Fermilab

    2011-12-01

    We study the usage of various definitions of sampling fractions in understanding electron shower shapes in a sampling multilayer electromagnetic calorimeter. We show that the sampling fractions obtained by the conventional definition (I) of (average observed energy in layer)/(average deposited energy in layer) will not give the best energy resolution for the calorimeter. The reason for this is shown to be the presence of layer by layer correlations in an electromagnetic shower. The best resolution is obtained by minimizing the deviation from the total input energy using a least squares algorithm. The 'sampling fractions' obtained by this method (II) are shown to give the best resolution for overall energy. We further show that the method (II) sampling fractions are obtained by summing the columns of a non-local {lambda} tensor that incorporates the correlations. We establish that the sampling fractions (II) cannot be used to predict the layer by layer energies and that one needs to employ the full {lambda} tensor for this purpose. This effect is again a result of the correlations.

  4. Predictive modeling of nanomaterial exposure effects in biological systems

    PubMed Central

    Liu, Xiong; Tang, Kaizhi; Harper, Stacey; Harper, Bryan; Steevens, Jeffery A; Xu, Roger

    2013-01-01

    Background Predictive modeling of the biological effects of nanomaterials is critical for industry and policymakers to assess the potential hazards resulting from the application of engineered nanomaterials. Methods We generated an experimental dataset on the toxic effects experienced by embryonic zebrafish due to exposure to nanomaterials. Several nanomaterials were studied, such as metal nanoparticles, dendrimer, metal oxide, and polymeric materials. The embryonic zebrafish metric (EZ Metric) was used as a screening-level measurement representative of adverse effects. Using the dataset, we developed a data mining approach to model the toxic endpoints and the overall biological impact of nanomaterials. Data mining techniques, such as numerical prediction, can assist analysts in developing risk assessment models for nanomaterials. Results We found several important attributes that contribute to the 24 hours post-fertilization (hpf) mortality, such as dosage concentration, shell composition, and surface charge. These findings concur with previous studies on nanomaterial toxicity using embryonic zebrafish. We conducted case studies on modeling the overall effect/impact of nanomaterials and the specific toxic endpoints such as mortality, delayed development, and morphological malformations. The results show that we can achieve high prediction accuracy for certain biological effects, such as 24 hpf mortality, 120 hpf mortality, and 120 hpf heart malformation. The results also show that the weighting scheme for individual biological effects has a significant influence on modeling the overall impact of nanomaterials. Sample prediction models can be found at http://neiminer.i-a-i.com/nei_models. Conclusion The EZ Metric-based data mining approach has been shown to have predictive power. The results provide valuable insights into the modeling and understanding of nanomaterial exposure effects. PMID:24098077

  5. ASSESSING MULTIMEDIA/MULTIPATHWAY EXPOSURE TO ARSENIC USING A MECHANISTIC SOURCE-TO-DOSE MODELING FRAMEWORK

    EPA Science Inventory

    A series of case studies is presented focusing on multimedia/multipathway population exposures to arsenic, employing the Population Based Modeling approach of the MENTOR (Modeling Environment for Total Risks) framework. This framework considers currently five exposure routes: i...

  6. MODELED ESTIMATES OF CHLORPYRIFOS EXPOSURE AND DOSE FOR THE MINNESOTA AND ARIZONA NHEXAS POPULATIONS

    EPA Science Inventory

    This paper presents a probabilistic, multimedia, multipathway exposure model and assessment for chlorpyrifos developed as part of the National Human Exposure Assessment Survey (NHEXAS). The model was constructed using available information prior to completion of the NHEXAS stu...

  7. Inhalation Exposure Input Parameters for the Biosphere Model

    SciTech Connect

    K. Rautenstrauch

    2004-09-10

    This analysis is one of 10 reports that support the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN) biosphere model. The ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes in detail the conceptual model as well as the mathematical model and its input parameters. This report documents development of input parameters for the biosphere model that are related to atmospheric mass loading and supports the use of the model to develop biosphere dose conversion factors (BDCFs). The biosphere model is one of a series of process models supporting the total system performance assessment (TSPA) for a Yucca Mountain repository. Inhalation Exposure Input Parameters for the Biosphere Model is one of five reports that develop input parameters for the biosphere model. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows the interrelationships among the products (i.e., analysis and model reports) developed for biosphere modeling, and the plan for development of the biosphere abstraction products for TSPA, as identified in the Technical Work Plan for Biosphere Modeling and Expert Support (BSC 2004 [DIRS 169573]). This analysis report defines and justifies values of mass loading for the biosphere model. Mass loading is the total mass concentration of resuspended particles (e.g., dust, ash) in a volume of air. Mass loading values are used in the air submodel of ERMYN to calculate concentrations of radionuclides in air inhaled by a receptor and concentrations in air surrounding crops. Concentrations in air to which the receptor is exposed are then used in the inhalation submodel to calculate the dose contribution to the receptor from inhalation of contaminated airborne particles. Concentrations in air surrounding plants are used in the plant submodel to calculate the concentrations of radionuclides in foodstuffs contributed from uptake by foliar interception.

  8. Hadron shower decomposition in a highly granular calorimeter

    NASA Astrophysics Data System (ADS)

    Chadeeva, Marina; CALICE Collaboration

    2015-02-01

    The spatial development of showers induced by positive hadrons with momenta 10-80 GeV in the highly granular CALICE scintillator-steel analogue hadronic calorimeter is analysed. The parametrisation of both longitudinal and radial shower profiles with the two- component functions are fit to the test beam data and simulations using the physics lists QGSP_BERT and FTFP_BERT from GEANT4 version 9.6 patch 01. The shower parameters, describing the longitudinal tail and radial halo, are in good agreement between data and simulations and are similar for pions and protons. For the longitudinal development, the most significant difference between data and simulations is in the relative containment of the separated components. For the radial development, the core slope parameter is underestimated by simulations. The physics list FTFP_BERT gives a very good description of proton showers in the studied energy range and gives better predictions of the pion shower development than QGSP_BERT.

  9. Probing the radio emission from air showers with polarization measurements

    NASA Astrophysics Data System (ADS)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bardenet, R.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Foerster, N.; Fox, B. D.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giammarchi, M.; Giller, M.; Gitto, J.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kadija, K.; Kambeitz, O.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; PeÂķala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Pontz, M.; Porcelli, A.; Preda, T.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Straub, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Taşcǎu, O.; Thao, N. T.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Tridapalli, D. B.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Pierre Auger Collaboration

    2014-03-01

    The emission of radio waves from air showers has been attributed to the so-called geomagnetic emission process. At frequencies around 50 MHz this process leads to coherent radiation which can be observed with rather simple setups. The direction of the electric field induced by this emission process depends only on the local magnetic field vector and on the incoming direction of the air shower. We report on measurements of the electric field vector where, in addition to this geomagnetic component, another component has been observed that cannot be described by the geomagnetic emission process. The data provide strong evidence that the other electric field component is polarized radially with respect to the shower axis, in agreement with predictions made by Askaryan who described radio emission from particle showers due to a negative charge excess in the front of the shower. Our results are compared to calculations which include the radiation mechanism induced by this charge-excess process.

  10. Showering cosmogenic muons in a large liquid scintillator

    NASA Astrophysics Data System (ADS)

    Grassi, Marco; Evslin, Jarah; Ciuffoli, Emilio; Zhang, Xinmin

    2014-09-01

    We present the results of FLUKA simulations of the propagation of cosmogenic muons in a 20 kton spherical liquid scintillator detector underneath 700 to 900 meters of rock. A showering muon is one which deposits at least 3 GeV in the detector in addition to ionization energy. We find that 20 percent of muons are showering and a further 11 percent of muon events are muon bundles, of which more than one muon enters the detector. In this range the showering and bundle fractions are robust against changes in the depth and topography, thus the total shower and bundle rate for a given experiment can be obtained by combining our results with an estimate for the total muon flux. One consequence is that a straightforward adaptation of the full detector showering muon cuts used by KamLAND to JUNO or RENO 50 would yield a nearly vanishing detector efficiency.

  11. Feasibility of radar detection of extensive air showers

    NASA Astrophysics Data System (ADS)

    Stasielak, J.; Engel, R.; Baur, S.; Neunteufel, P.; Šmída, R.; Werner, F.; Wilczyński, H.

    2016-01-01

    Reflection of radio waves off the short-lived plasma produced by the high-energy shower particles in the air is simulated, considering various radar setups and shower geometries. We show that the plasma produced by air showers has to be treated always as underdense. Therefore, we use the Thomson cross-section for scattering of radio waves corrected for molecular quenching and we sum coherently contributions of the reflected radio wave over the volume of the plasma disk to obtain the time evolution of the signal arriving at the receiver antenna. The received power and the spectral power density of the radar echo are analyzed. Based on the obtained results, we discuss possible modes of radar detection of extensive air showers. We conclude that the scattered signal is too weak for the radar method to provide an efficient and inexpensive method of air shower detection.

  12. Optical fluxes and meteor properties of the camelopardalid meteor shower

    NASA Astrophysics Data System (ADS)

    Campbell-Brown, M. D.; Blaauw, R.; Kingery, A.

    2016-10-01

    Observations of the Camelopardalid meteor shower in May 2014 were obtained with six different sets of cameras, with limiting meteor magnitudes varying from -2M to +7M. Shower fluxes were calculated for each of the systems, from which the mass index of the shower was found to be 2.17 ± 0.04. Faint meteors in the shower were found to be stronger than average, ablating at lower altitudes than meteors at the same speed recorded with the same system, while the brightest meteors had higher ablation heights and were therefore weaker than typical meteors. These findings can be explained if large Camelopardalids are weak agglomerations of more refractory grains, which are easily disrupted in space and keep the shower supplied with small material and depleted in large material.

  13. Analysis of School Commuting Data for Exposure Modeling Purposes

    SciTech Connect

    Xue, Jianping; McCurdy, Thomas; Burke, Janet; Bhaduri, Budhendra L; Liu, Cheng; Nutaro, James J; Patterson, Lauren A

    2010-01-01

    Human exposure models often make the simplifying assumption that school children attend school in the same census tract where they live. This paper analyzes that assumption and provides information on the temporal and spatial distributions associated with school commuting. The data were obtained using Oak Ridge National Laboratory s LandScan USA population distribution model (Bhaduri et al., 2007) applied to Philadelphia PA. It is a high-resolution model used to allocate individual school-aged children to both a home and school location, and to devise a minimum-time home-to school commuting path (called a trace) between the two locations. LandScan relies heavily on Geographic Information System (GIS) data. Our GIS analyses found that in Philadelphia: (1) about 32% of the students walk across 2 or more census tracts and 40% of them walk across 4 or more census blocks; (2) 60% drive across 4 or more census tracts going to school and 50% drive across 10 or more census blocks; (3) five-minute commuting time intervals result in misclassification as high as 90% for census blocks, 70% for block groups, and 50% for census tracts; (4) a one-minute time interval is needed to reasonably resolve time spent in the various census unit designations; (5) approximately 50% of both schoolchildren s homes and schools are located within 160 m of highly-traveled roads, and 64% of the schools are located within 200 m. These findings are very important when modeling school children s exposures, especially when ascertaining the impacts of near-roadway concentrations on their total daily body burden. Since many school children also travel along these streets and roadways to get to school, a majority of children in Philadelphia are in mobile-source dominated locations most of the day. We hypothesize that exposures of school children in Philadelphia to benzene and particulate matter will be much higher than if home and school locations and commuting paths at a 1-minute time resolution are

  14. KREAM: Korean Radiation Exposure Assessment Model for Aviation Route Dose

    NASA Astrophysics Data System (ADS)

    Hwang, J.; Dokgo, K.; Choi, E. J.; Kim, K. C.; Kim, H. P.; Cho, K. S. F.

    2014-12-01

    Since Korean Air has begun to use the polar route from Seoul/ICN airport to New York/JFK airport on August 2006, there are explosive needs for the estimation and prediction against cosmic radiation exposure for Korean aircrew and passengers in South Korea from public. To keep pace with those needs of public, Korean government made the law on safety standards and managements of cosmic radiation for the flight attendants and the pilots in 2013. And we have begun to develop our own Korean Radiation Exposure Assessment Model (KREAM) for aviation route dose since last year funded by Korea Meteorological Administration (KMA). GEANT4 model and NRLMSIS 00 model are used for calculation of the energetic particles' transport in the atmosphere and for obtaining the background atmospheric neutral densities depending on altitude. For prediction the radiation exposure in many routes depending on the various space weather effects, we constructed a database from pre-arranged simulations using all possible combinations of R, S, and G, which are the space weather effect scales provided by the National Oceanic and Atmospheric Administration (NOAA). To get the solar energetic particles' spectrum at the 100 km altitude which we set as a top of the atmospheric layers in the KREAM, we use ACE and GOES satellites' proton flux observations. We compare the results between KREAM and the other cosmic radiation estimation programs such as CARI-6M which is provided by the Federal Aviation Agency (FAA). We also validate KREAM's results by comparison with the measurement from Liulin-6K LET spectrometer onboard Korean commercial flights and Korean Air Force reconnaissance flights.

  15. SHEDS-HT: An Integrated Probabilistic Exposure Model for Prioritizing Exposures to Chemicals with Near-Field and Dietary Sources

    EPA Science Inventory

    United States Environmental Protection Agency (USEPA) researchers are developing a strategy for highthroughput (HT) exposure-based prioritization of chemicals under the ExpoCast program. These novel modeling approaches for evaluating chemicals based on their potential for biologi...

  16. 75 FR 39014 - Exposure Modeling Public Meeting; Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-07

    ... AGENCY Exposure Modeling Public Meeting; Notice of Public Meeting AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: An Exposure Modeling Public Meeting (EMPM) will be held for 1 day on... number is (703) 305-5805. II. Background On a biannual interval, an Exposure Modeling Public Meeting...

  17. Reducing uncertainty in risk modeling for methylmercury exposure

    SciTech Connect

    Ponce, R.; Egeland, G.; Middaugh, J.; Lee, R.

    1995-12-31

    The biomagnification and bioaccumulation of methylmercury in marine species represents a challenge for risk assessment related to the consumption of subsistence foods in Alaska. Because of the profound impact that food consumption advisories have on indigenous peoples seeking to preserve a way of life, there is a need to reduce uncertainty in risk assessment. Thus, research was initiated to reduce the uncertainty in assessing the health risks associated with the consumption of subsistence foods. Because marine subsistence foods typically contain elevated levels of methylmercury, preliminary research efforts have focused on methylmercury as the principal chemical of concern. Of particular interest are the antagonistic effects of selenium on methylmercury toxicity. Because of this antagonism, methylmercury exposure through the consumption of marine mammal meat (with high selenium) may not be as toxic as comparable exposures through other sources of dietary intake, such as in the contaminated bread episode of Iraq (containing relatively low selenium). This hypothesis is supported by animal experiments showing reduced toxicity of methylmercury associated with marine mammal meat, by the antagonistic influence of selenium on methylmercury toxicity, and by negative clinical findings in adult populations exposed to methylmercury through a marine diet not subject to industrial contamination. Exploratory model development is underway to identify potential improvements and applications of current deterministic and probabilistic models, particularly by incorporating selenium as an antagonist in risk modeling methods.

  18. Chromosome aberrations as biomarkers of radiation exposure: Modelling basic mechanisms

    NASA Astrophysics Data System (ADS)

    Ballarini, F.; Ottolenghi, A.

    The space radiation environment is a mixed field consisting of different particles having different energies, including high charge and energy (HZE) ions. Conventional measurements of absorbed doses may not be sufficient to completely characterise the radiation field and perform reliable estimates of health risks. Biological dosimetry, based on the observation of specific radiation-induced endpoints (typically chromosome aberrations), can be a helpful approach in case of monitored exposure to space radiation or other mixed fields, as well as in case of accidental exposure. Furthermore, various ratios of aberrations (e.g. dicentric chromosomes to centric rings and complex exchanges to simple exchanges) have been suggested as possible fingerprints of radiation quality, although all of them have been subjected to some criticisms. In this context a mechanistic model and a Monte Carlo code for the simulation of chromosome aberration induction were developed. The model, able to provide dose-responses for different aberrations (e.g. dicentrics, rings, fragments, translocations, insertions and other complex exchanges), was further developed to assess the dependence of various ratios of aberrations on radiation quality. The predictions of the model were compared with available data, whose experimental conditions were faithfully reproduced. Particular attention was devoted to the scoring criteria adopted in different laboratories and to possible biases introduced by interphase death and mitotic delay. This latter aspect was investigated by taking into account both metaphase data and data obtained with Premature Chromosome Condensation (PCC).

  19. Chromosome aberrations as biomarkers of radiation exposure: modelling basic mechanisms.

    PubMed

    Ballarini, F; Ottolenghi, A

    2003-01-01

    The space radiation environment is a mixed field consisting of different particles having different energies, including high charge and energy (HZE) ions. Conventional measurements of absorbed doses may not be sufficient to completely characterise the radiation field and perform reliable estimates of health risks. Biological dosimetry, based on the observation of specific radiation-induced endpoints (typically chromosome aberrations), can be a helpful approach in case of monitored exposure to space radiation or other mixed fields, as well as in case of accidental exposure. Furthermore, various ratios of aberrations (e.g. dicentric chromosomes to centric rings and complex exchanges to simple exchanges) have been suggested as possible fingerprints of radiation quality, although all of them have been subjected to some criticisms. In this context a mechanistic model and a Monte Carlo code for the simulation of chromosome aberration induction were developed. The model, able to provide dose-responses for different aberrations (e.g. dicentrics, rings, fragments, translocations, insertions and other complex exchanges), was further developed to assess the dependence of various ratios of aberrations on radiation quality. The predictions of the model were compared with available data, whose experimental conditions were faithfully reproduced. Particular attention was devoted to the scoring criteria adopted in different laboratories and to possible biases introduced by interphase death and mitotic delay. This latter aspect was investigated by taking into account both metaphase data and data obtained with Premature Chromosome Condensation (PCC). PMID:12971411

  20. Exposure estimates using urban plume dispersion and traffic microsimulation models

    SciTech Connect

    Brown, M.J.; Mueller, C.; Bush, B.; Stretz, P.

    1997-12-01

    The goal of this research effort was to demonstrate a capability for analyzing emergency response issues resulting from accidental or mediated airborne toxic releases in an urban setting. In the first year of the program, the authors linked a system of fluid dynamics, plume dispersion, and vehicle transportation models developed at Los Alamos National Laboratory to study the dispersion of a plume in an urban setting and the resulting exposures to vehicle traffic. This research is part of a larger laboratory-directed research and development project for studying the relationships between urban infrastructure elements and natural systems.

  1. Arrival directions of large air showers, low-mu showers and old-age low-mu air showers observed at St. Chacaltaya

    NASA Technical Reports Server (NTRS)

    Kaneko, T.; Hagiwara, K.; Yoshii, H.; Martinic, N.; Siles, L.; Miranda, P.; Kakimoto, F.; Obara, T.; Inoue, N.; Suga, K.

    1985-01-01

    Arrival directions of air showers with primary energies in the range 10 to the 16.5 power eV to 10 to the 18th power eV show the first harmonic in right ascension (RA) with amplitude of 2.7 + or - 1.0% and phase of 13-16h. However, the second harmonic in RA slightly seen for showers in the range 10 to the 18th power eV to 10 to the 19th power eV disappeared by accumulation of observed showers. The distribution of arrival directions of low-mu air showers with primary energies around 10 to the 15th power eV observed at Chacaltaya from 1962 to 1967 is referred to, relating to the above-mentioned first harmonic. Also presented in this paper are arrival directions of old-age low-mu air showers observed at Chacaltaya from 1962 to 1967, for recent interest in gamma-ray air showers.

  2. UNITED STATES METEOROLOGICAL DATA - DAILY AND HOURLY FILES TO SUPPORT PREDICTIVE EXPOSURE MODELING

    EPA Science Inventory

    ORD numerical models for pesticide exposure include a model of spray drift (AgDisp), a cropland pesticide persistence model (PRZM), a surface water exposure model (EXAMS), and a model of fish bioaccumulation (BASS). A unified climatological database for these models has been asse...

  3. Measurement of shower electrons and muons using a small air shower array

    NASA Technical Reports Server (NTRS)

    Chan, S. K.; Ng, L. K.

    1985-01-01

    A small air shower array has been used to measure the size spectrum of air showers at sea level in the size range 6.10 to the 3rd power to 10 to the 6th power. The result fitted with the power law gives an index 2.79 + or - 0.11 for the differential spectrum. Lateral distribution of electrons fitted with the well known NKG function results in an age parameter s = 1.35 for core distances less than 30m and s = 0.8 for longer core distances. Lateral distribution of muons follows the general shape of Greisen's relation but is much higher in intensity. Muon and electron densities at the same observation point are also compared.

  4. Detection of Cherenkov light from air showers with Geiger-APDs

    NASA Astrophysics Data System (ADS)

    Otte, A.N. Britvich, I.; Biland, A.; Goebel, F.; Lorenz, E.; Pauss, F.; Renker, D.; Röser, U.; Schweizer, T.

    We have detected Cherenkov light from air showers with Geiger-mode APDs (G-APDs). G-APDs are novel semiconductor photon-detectors which offer several advantages compared to conventional photomultiplier tubes in the field of air shower detection. Folded with the Cherenkov spectrum the response of G-APDs is up to a factor of three higher if compared with classical photomultipliers. Moreover they offer high gain (~105-106) at low operation voltages (<100 V). Under operation they can withstand excessive and prolonged exposure to bright light and are also mechanical robust. Dark count rates of some G-APDs are below the level of light coming from the night sky. Furthermore G-APDs can be mass-produced which allows to considerably reduce the costs of these sensors. According to the present state of the development of G-APD they promise to be a major progress for gamma-ray astronomy. Here we report on the detection of Cherenkov light from air showers with G-APD. We discuss first test results and the advantages and problems of G-APDs in Cherenkov telescopes.

  5. Astronaut EVA exposure estimates from CAD model spacesuit geometry.

    PubMed

    De Angelis, Giovanni; Anderson, Brooke M; Atwell, William; Nealy, John E; Qualls, Garry D; Wilson, John W

    2004-03-01

    Ongoing assembly and maintenance activities at the International Space Station (ISS) require much more extravehicular activity (EVA) than did the earlier U.S. Space Shuttle missions. It is thus desirable to determine and analyze, and possibly foresee, as accurately as possible what radiation exposures crew members involved in EVAs will experience in order to minimize risks and to establish exposure limits that must not to be exceeded. A detailed CAD model of the U.S. Space Shuttle EVA Spacesuit, developed at NASA Langley Research Center (LaRC), is used to represent the directional shielding of an astronaut; it has detailed helmet and backpack structures, hard upper torso, and multilayer space suit fabric material. The NASA Computerized Anatomical Male and Female (CAM and CAF) models are used in conjunction with the space suit CAD model for dose evaluation within the human body. The particle environments are taken from the orbit-averaged NASA AP8 and AE8 models at solar cycle maxima and minima. The transport of energetic particles through space suit materials and body tissue is calculated by using the NASA LaRC HZETRN code for hadrons and a recently developed deterministic transport code, ELTRN, for electrons. The doses within the CAM and CAF models are determined from energy deposition at given target points along 968 directional rays convergent on the points and are evaluated for several points on the skin and within the body. Dosimetric quantities include contributions from primary protons, light ions, and electrons, as well as from secondary brehmsstrahlung and target fragments. Directional dose patterns are displayed as rays and on spherical surfaces by the use of a color relative intensity representation. PMID:15133283

  6. Astronaut EVA exposure estimates from CAD model spacesuit geometry.

    PubMed

    De Angelis, Giovanni; Anderson, Brooke M; Atwell, William; Nealy, John E; Qualls, Garry D; Wilson, John W

    2004-03-01

    Ongoing assembly and maintenance activities at the International Space Station (ISS) require much more extravehicular activity (EVA) than did the earlier U.S. Space Shuttle missions. It is thus desirable to determine and analyze, and possibly foresee, as accurately as possible what radiation exposures crew members involved in EVAs will experience in order to minimize risks and to establish exposure limits that must not to be exceeded. A detailed CAD model of the U.S. Space Shuttle EVA Spacesuit, developed at NASA Langley Research Center (LaRC), is used to represent the directional shielding of an astronaut; it has detailed helmet and backpack structures, hard upper torso, and multilayer space suit fabric material. The NASA Computerized Anatomical Male and Female (CAM and CAF) models are used in conjunction with the space suit CAD model for dose evaluation within the human body. The particle environments are taken from the orbit-averaged NASA AP8 and AE8 models at solar cycle maxima and minima. The transport of energetic particles through space suit materials and body tissue is calculated by using the NASA LaRC HZETRN code for hadrons and a recently developed deterministic transport code, ELTRN, for electrons. The doses within the CAM and CAF models are determined from energy deposition at given target points along 968 directional rays convergent on the points and are evaluated for several points on the skin and within the body. Dosimetric quantities include contributions from primary protons, light ions, and electrons, as well as from secondary brehmsstrahlung and target fragments. Directional dose patterns are displayed as rays and on spherical surfaces by the use of a color relative intensity representation.

  7. Probabilistic modelling of European consumer exposure to cosmetic products.

    PubMed

    McNamara, C; Rohan, D; Golden, D; Gibney, M; Hall, B; Tozer, S; Safford, B; Coroama, M; Leneveu-Duchemin, M C; Steiling, W

    2007-11-01

    In this study, we describe the statistical analysis of the usage profile of the European population to seven cosmetic products. The aim of the study was to construct a reliable model of exposure of the European population from use of the selected products: body lotion, shampoo, deodorant spray, deodorant non-spray, facial moisturiser, lipstick and toothpaste. The first step in this process was to gather reliable data on consumer usage patterns of the products. These data were sourced from a combination of market information databases and a controlled product use study by the trade association Colipa. The market information study contained a large number of subjects, in total 44,100 households and 18,057 habitual users (males and females) of the studied products, in five European countries. The data sets were then combined to generate a realistic distribution of frequency of use of each product, combined with distribution of the amount of product used at each occasion using the CREMe software. A Monte Carlo method was used to combine the data sets. This resulted in a new model of European exposure to cosmetic products being constructed.

  8. Use of an aggregate exposure model to estimate consumer exposure to fragrance ingredients in personal care and cosmetic products.

    PubMed

    Safford, B; Api, A M; Barratt, C; Comiskey, D; Daly, E J; Ellis, G; McNamara, C; O'Mahony, C; Robison, S; Smith, B; Thomas, R; Tozer, S

    2015-08-01

    Ensuring the toxicological safety of fragrance ingredients used in personal care and cosmetic products is essential in product development and design, as well as in the regulatory compliance of the products. This requires an accurate estimation of consumer exposure which, in turn, requires an understanding of consumer habits and use of products. Where ingredients are used in multiple product types, it is important to take account of aggregate exposure in consumers using these products. This publication investigates the use of a newly developed probabilistic model, the Creme RIFM model, to estimate aggregate exposure to fragrance ingredients using the example of 2-phenylethanol (PEA). The output shown demonstrates the utility of the model in determining systemic and dermal exposure to fragrances from individual products, and aggregate exposure. The model provides valuable information not only for risk assessment, but also for risk management. It should be noted that data on the concentrations of PEA in products used in this article were obtained from limited sources and not the standard, industry wide surveys typically employed by the fragrance industry and are thus presented here to illustrate the output and utility of the newly developed model. They should not be considered an accurate representation of actual exposure to PEA.

  9. Use of an aggregate exposure model to estimate consumer exposure to fragrance ingredients in personal care and cosmetic products.

    PubMed

    Safford, B; Api, A M; Barratt, C; Comiskey, D; Daly, E J; Ellis, G; McNamara, C; O'Mahony, C; Robison, S; Smith, B; Thomas, R; Tozer, S

    2015-08-01

    Ensuring the toxicological safety of fragrance ingredients used in personal care and cosmetic products is essential in product development and design, as well as in the regulatory compliance of the products. This requires an accurate estimation of consumer exposure which, in turn, requires an understanding of consumer habits and use of products. Where ingredients are used in multiple product types, it is important to take account of aggregate exposure in consumers using these products. This publication investigates the use of a newly developed probabilistic model, the Creme RIFM model, to estimate aggregate exposure to fragrance ingredients using the example of 2-phenylethanol (PEA). The output shown demonstrates the utility of the model in determining systemic and dermal exposure to fragrances from individual products, and aggregate exposure. The model provides valuable information not only for risk assessment, but also for risk management. It should be noted that data on the concentrations of PEA in products used in this article were obtained from limited sources and not the standard, industry wide surveys typically employed by the fragrance industry and are thus presented here to illustrate the output and utility of the newly developed model. They should not be considered an accurate representation of actual exposure to PEA. PMID:26071898

  10. Fast Simulation of Electromagnetic Showers in the ATLAS Calorimeter: Frozen Showers

    SciTech Connect

    Barberio, E.; Boudreau, J.; Butler, B.; Cheung, S.L.; Dell'Acqua, A.; Di Simone, A.; Ehrenfeld, E.; Gallas, M.V.; Glazov, A.; Marshall, Z.; Mueller, J.; Placakyte, R.; Rimoldi, A.; Savard, P.; Tsulaia, V.; Waugh, A.; Young, C.C.; /SLAC

    2011-11-29

    One of the most time consuming process simulating pp interactions in the ATLAS detector at LHC is the simulation of electromagnetic showers in the calorimeter. In order to speed up the event simulation several parametrisation methods are available in ATLAS. In this paper we present a short description of a frozen shower technique, together with some recent benchmarks and comparison with full simulation. An expected high rate of proton-proton collisions in ATLAS detector at LHC requires large samples of simulated events (Monte Carlo) to study various physics processes. A detailed simulation of particle reactions ('full simulation') in the ATLAS detector is based on GEANT4 and is very accurate. However, due to complexity of the detector, high particle multiplicity and GEANT4 itself, the average CPU time spend to simulate typical QCD event in pp collision is 20 or more minutes for modern computers. During detector simulation the largest time is spend in the calorimeters (up to 70%) most of which is required for electromagnetic particles in the electromagnetic (EM) part of the calorimeters. This is the motivation for fast simulation approaches which reduce the simulation time without affecting the accuracy. Several of fast simulation methods available within the ATLAS simulation framework (standard Athena based simulation program) are discussed here with the focus on the novel frozen shower library (FS) technique. The results obtained with FS are presented here as well.

  11. Small air showers and collider physics

    NASA Technical Reports Server (NTRS)

    Capdevielle, J. N.; Gawin, J.; Grochalska, B.

    1985-01-01

    At energies lower than 2.5 X 10 to the 5 GeV (in Lab. system), more accurate information on nucleon-nucleon collision (p-p collider and on primary composition now exist. The behavior of those both basic elements in cosmic ray phenomenology from ISR energy suggests some tendencies for reasonable extrapolation in the next decade 2.0x10 to the 5 to 2.0x10 to the 6 GeV. Small showers in altitude, recorded in the decade 2 X 10 to the 4 to 2 X 10 to the 5 GeV offers a good tool to testify the validity of all the Monte-Carlo simulation analysis and appreciate how nucleon-air collision are different from nucleon-nucleon collisions.

  12. Simulation of radiation energy release in air showers

    NASA Astrophysics Data System (ADS)

    Glaser, Christian; Erdmann, Martin; Hörandel, Jörg R.; Huege, Tim; Schulz, Johannes

    2016-09-01

    A simulation study of the energy released by extensive air showers in the form of MHz radiation is performed using the CoREAS simulation code. We develop an efficient method to extract this radiation energy from air-shower simulations. We determine the longitudinal profile of the radiation energy release and compare it to the longitudinal profile of the energy deposit by the electromagnetic component of the air shower. We find that the radiation energy corrected for the geometric dependence of the geomagnetic emission scales quadratically with the energy in the electromagnetic component of the air shower with a second-order dependence on the atmospheric density at the position of the maximum shower development Xmax. In a measurement where Xmax is not accessible, this second order dependence can be approximated using the zenith angle of the incoming direction of the air shower with only a minor loss in accuracy. Our method results in an intrinsic uncertainty of 4% in the determination of the energy in the electromagnetic air-shower component, which is well below current experimental uncertainties.

  13. Polarized radio emission from extensive air showers measured with LOFAR

    SciTech Connect

    Schellart, P.; Buitink, S.; Corstanje, A.; Enriquez, J.E.; Falcke, H.; Hörandel, J.R.; Krause, M.; Nelles, A.; Rachen, J.P.; Veen, S. ter; Thoudam, S.

    2014-10-01

    We present LOFAR measurements of radio emission from extensive air showers. We find that this emission is strongly polarized, with a median degree of polarization of nearly 99%, and that the angle between the polarization direction of the electric field and the Lorentz force acting on the particles, depends on the observer location in the shower plane. This can be understood as a superposition of the radially polarized charge-excess emission mechanism, first proposed by Askaryan and the geomagnetic emission mechanism proposed by Kahn and Lerche. We calculate the relative strengths of both contributions, as quantified by the charge-excess fraction, for 163 individual air showers. We find that the measured charge-excess fraction is higher for air showers arriving from closer to the zenith. Furthermore, the measured charge-excess fraction also increases with increasing observer distance from the air shower symmetry axis. The measured values range from (3.3± 1.0)% for very inclined air showers at 25 m to (20.3± 1.3)% for almost vertical showers at 225 m. Both dependencies are in qualitative agreement with theoretical predictions.

  14. 77 FR 15099 - Exposure Modeling Public Meeting; Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-14

    ... Kinetics in Environmental Media Pesticide Root Zone Model--Ground Water (PRZM-GW) Update Measuring and... Modeling List of Subjects Environmental protection, Degradation kinetics, Exposure assessment,...

  15. PBDE exposure from food in Ireland: optimising data exploitation in probabilistic exposure modelling.

    PubMed

    Trudel, David; Tlustos, Christina; Von Goetz, Natalie; Scheringer, Martin; Hungerbühler, Konrad

    2011-01-01

    Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants added to plastics, polyurethane foam, electronics, textiles, and other products. These products release PBDEs into the indoor and outdoor environment, thus causing human exposure through food and dust. This study models PBDE dose distributions from ingestion of food for Irish adults on congener basis by using two probabilistic and one semi-deterministic method. One of the probabilistic methods was newly developed and is based on summary statistics of food consumption combined with a model generating realistic daily energy supply from food. Median (intermediate) doses of total PBDEs are in the range of 0.4-0.6 ng/kg(bw)/day for Irish adults. The 97.5th percentiles of total PBDE doses lie in a range of 1.7-2.2 ng/kg(bw)/day, which is comparable to doses derived for Belgian and Dutch adults. BDE-47 and BDE-99 were identified as the congeners contributing most to estimated intakes, accounting for more than half of the total doses. The most influential food groups contributing to this intake are lean fish and salmon which together account for about 22-25% of the total doses.

  16. Inhalation Exposure Input Parameters for the Biosphere Model

    SciTech Connect

    M. A. Wasiolek

    2003-09-24

    This analysis is one of the nine reports that support the Environmental Radiation Model for Yucca Mountain Nevada (ERMYN) biosphere model. The ''Biosphere Model Report'' (BSC 2003a) describes in detail the conceptual model as well as the mathematical model and its input parameters. This report documents a set of input parameters for the biosphere model, and supports the use of the model to develop biosphere dose conversion factors (BDCFs). The biosphere model is one of a series of process models supporting the Total System Performance Assessment (TSPA) for a Yucca Mountain repository. This report, ''Inhalation Exposure Input Parameters for the Biosphere Model'', is one of the five reports that develop input parameters for the biosphere model. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows the interrelationships among the products (i.e., analysis and model reports) developed for biosphere modeling, and the plan for development of the biosphere abstraction products for TSPA, as identified in the ''Technical Work Plan: for Biosphere Modeling and Expert Support'' (BSC 2003b). It should be noted that some documents identified in Figure 1-1 may be under development at the time this report is issued and therefore not available at that time. This figure is included to provide an understanding of how this analysis report contributes to biosphere modeling in support of the license application, and is not intended to imply that access to the listed documents is required to understand the contents of this analysis report. This analysis report defines and justifies values of mass loading, which is the total mass concentration of resuspended particles (e.g., dust, ash) in a volume of air. Measurements of mass loading are used in the air submodel of ERMYN to calculate concentrations of radionuclides in air surrounding crops and concentrations in air inhaled by a receptor. Concentrations in air to which the

  17. External exposure model in the RESRAD computer code.

    SciTech Connect

    Kamboj, S.; Yu, C.; Environmental Assessment

    2002-06-01

    An external exposure model has been developed for the RESRAD computer code that provides flexibility in modeling soil contamination configurations for calculating external doses to exposed individuals. This model is based on the dose coefficients given in the U.S. Environmental Protection Agency's Federal Guidance Report No. 12 (FGR-12) and the point kernel method. It extends the applicability of FGR-12 data to include the effects of different source geometries, such as cover thickness, source thickness, source area, and shape of contaminated area of a specific site. A depth factor function was developed to express the dependence of the dose on the source thickness. A cover-and-depth factor function, derived from this depth factor function, takes into account the dependence of dose on the thickness of the source region and the thickness of the cover above the source region. To further extend the model for realistic geometries, area and shape factors were derived that depend not only on the lateral extent of the contamination, but also on source thickness, cover thickness, and radionuclides present. Results obtained with the model generally compare well with those from the Monte Carlo N-Particle transport code.

  18. Angular resolution of air-shower array-telescopes

    NASA Technical Reports Server (NTRS)

    Linsley, J.

    1985-01-01

    A fundamental limit on the angular resolution of air shower array-telescopes is set by the finite number of shower particles coupled with the finite thickness of the particle swarm. Consequently the angular resolution which can be achieved in practice depends in a determinant manner on the size and number of detectors in an array-telescope, as well as on the detector separation and the timing resolution. It is also necessary to examine the meaning of particle density in whatever type of detector is used. Results are given which can be used to predict the angular resolution of a given instrument for showers of various sizes, and to compare different instruments.

  19. The Method of Selection of Major-Shower Meteors Revisited

    NASA Astrophysics Data System (ADS)

    Neslušan, L.; Svoreň, J.; Porubčan, V.

    2013-02-01

    We apply so-called break-point method to select the dense cores of 10 major meteor showers from the photographic, video, and radio-meteor databases. The major showers can well be selected from photographic and video data, in a lesser degree from radio data. The obtained mean characteristics of Quadrantids, Lyrids, η-Aquarids, α-Capricornids, δ-Aquarids N, δ-Aquarids S, Perseids, Orionids, Leonids, and Geminids are presented. A test to indicate the existence of a suspected shower in radio database is suggested.

  20. Detection of very inclined showers with the Auger Observatory

    SciTech Connect

    Nellen, Lukas; /Mexico U., ICN

    2005-07-01

    The Pierre Auger Observatory can detect air showers with high efficiency at large zenith angles with both the fluorescence and surface detectors. Since half the available solid angle corresponds to zeniths between 60 and 90 degrees, a large number of inclined events can be expected and are indeed observed. In this paper, we characterize the inclined air showers detected by the Observatory and we present the aperture for inclined showers and an outlook of the results that can be obtained in future studies of the inclined data set.

  1. A PROBABILISTIC POPULATION EXPOSURE MODEL FOR PM10 AND PM 2.5

    EPA Science Inventory

    A first generation probabilistic population exposure model for Particulate Matter (PM), specifically for predicting PM10, and PM2.5, exposures of an urban, population has been developed. This model is intended to be used to predict exposure (magnitude, frequency, and duration) ...

  2. Bremsstrahlung and pair creation: Suppression mechanisms and how they affect EHE air showers

    SciTech Connect

    Klein, S.R.

    1997-12-01

    Most calculations of air shower development have been based on the Bethe-Heitler cross sections for bremsstrahlung and pair production. However, for energetic enough particles, a number of different external factors can reduce these cross sections drastically, slowing shower development and lengthening the showers. Four mechanisms that can suppress bremsstrahlung and pair production cross sections are discussed, and their effect on extremely high energy air showers considered. Besides lengthening the showers, these mechanisms greatly increase the importance of fluctuations in shower development, and can increase the angular spreading of showers.

  3. ASSESSING POPULATION EXPOSURES TO MULTIPLE AIR POLLUTANTS USING A MECHANISTIC SOURCE-TO-DOSE MODELING FRAMEWORK

    EPA Science Inventory

    The Modeling Environment for Total Risks studies (MENTOR) system, combined with an extension of the SHEDS (Stochastic Human Exposure and Dose Simulation) methodology, provide a mechanistically consistent framework for conducting source-to-dose exposure assessments of multiple pol...

  4. An empirical assessment of exposure measurement error and effect attenuation in bi-pollutant epidemiologic models

    EPA Science Inventory

    Background: Using multipollutant models to understand combined health effects of exposure to multiple pollutants is becoming more common. However, complex relationships between pollutants and differing degrees of exposure error across pollutants can make health effect estimates f...

  5. An empirical assessment of exposure measurement errors and effect attenuation in bi-pollutant epidemiologic models

    EPA Science Inventory

    Using multipollutant models to understand the combined health effects of exposure to multiple pollutants is becoming more common. However, the complex relationships between pollutants and differing degrees of exposure error across pollutants can make health effect estimates from ...

  6. The time structure of hadronic showers in highly granular calorimeters with tungsten and steel absorbers

    NASA Astrophysics Data System (ADS)

    Adloff, C.; Blaising, J.-J.; Chefdeville, M.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Karyotakis, Y.; Koletsou, I.; Prast, J.; Vouters, G.; Repond, J.; Schlereth, J.; Xia, L.; Baldolemar, E.; Li, J.; Park, S. T.; Sosebee, M.; White, A. P.; Yu, J.; Eigen, G.; Thomson, M. A.; Ward, D. R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Arfaoui, S.; Benoit, M.; Dannheim, D.; Elsener, K.; Folger, G.; Grefe, C.; Ivantchenko, V.; Killenberg, M.; Klempt, W.; van der Kraaij, E.; Linssen, L.; Lucaci-Timoce, A.-I.; Münnich, A.; Poss, S.; Ribon, A.; Roloff, P.; Sailer, A.; Schlatter, D.; Sicking, E.; Strube, J.; Uzhinskiy, V.; Cârloganu, C.; Gay, P.; Manen, S.; Royer, L.; Cornett, U.; David, D.; Ebrahimi, A.; Falley, G.; Feege, N.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Karstensen, S.; Krivan, F.; Krüger, K.; Lu, S.; Lutz, B.; Morozov, S.; Morgunov, V.; Neubüser, C.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Terwort, M.; Fagot, A.; Tytgat, M.; Zaganidis, N.; Hostachy, J.-Y.; Morin, L.; Garutti, E.; Laurien, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Briggl, K.; Eckert, P.; Harion, T.; Schultz-Coulon, H.-Ch; Shen, W.; Stamen, R.; Chang, S.; Khan, A.; Kim, D. H.; Kong, D. J.; Oh, Y. D.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Wilson, G. W.; Kawagoe, K.; Miyazaki, Y.; Sudo, Y.; Ueno, H.; Yoshioka, T.; Dauncey, P. D.; Cortina Gil, E.; Mannai, S.; Baulieu, G.; Calabria, P.; Caponetto, L.; Combaret, C.; Della Negra, R.; Eté, R.; Grenier, G.; Han, R.; Ianigro, J.-C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Vander Donckt, M.; Zoccarato, Y.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Puerta-Pelayo, J.; Corriveau, F.; Bobchenko, B.; Chadeeva, M.; Danilov, M.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Rusinov, V.; Tarkovsky, E.; Kozlov, V.; Soloviev, Y.; Besson, D.; Buzhan, P.; Ilyin, A.; Kantserov, V.; Kaplin, V.; Popova, E.; Tikhomirov, V.; Gabriel, M.; Kiesling, C.; Seidel, K.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M. S.; Bonis, J.; Conforti di Lorenzo, S.; Cornebise, P.; Fleury, J.; Frisson, T.; van der Kolk, N.; Richard, F.; Pöschl, R.; Rouëné, J.; Anduze, M.; Balagura, V.; Becheva, E.; Boudry, V.; Brient, J.-C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Guliyev, E.; Haddad, Y.; Magniette, F.; Ruan, M.; Tran, T. H.; Videau, H.; Callier, S.; Dulucq, F.; Martin-Chassard, G.; de la Taille, Ch; Raux, L.; Seguin-Moreau, N.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Ghazlane, H.; Kotera, K.; Ono, H.; Takeshita, T.; Uozumi, S.; Chai, J. S.; Song, H. S.; Lee, S. H.; Götze, M.; Sauer, J.; Weber, S.; Zeitnitz, C.

    2014-07-01

    The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.

  7. Correlation of high energy muons with primary composition in extensive air shower

    NASA Technical Reports Server (NTRS)

    Chou, C.; Higashi, S.; Hiraoka, N.; Ozaki, S.; Sato, T.; Suwada, T.; Takahasi, T.; Umeda, H.

    1985-01-01

    An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in the range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep, Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed.

  8. CORSIKA implementation of heavy quark production and propagation in extensive air showers

    NASA Astrophysics Data System (ADS)

    Bueno, A.; Gascón, A.

    2014-02-01

    Heavy quarks are commonly produced in current accelerator experiments. Hence it is natural to think that they should be likewise created in collisions with larger center of mass energies like the ones involving ultra-high energy cosmic rays and atmospheric nuclei. Despite this fact, a detailed treatment of heavy hadrons is missing in Monte Carlo generators of Extensive Air Showers (EAS). It is a must to improve the description of how heavy flavors appear and evolve in atmospheric showers. With this goal in mind, we study two different models for heavy quark production in proton-air collisions. We also analyze a dedicated treatment of heavy hadrons interactions with atmospheric nuclei. This paper shows how those models have been implemented as new options available in CORSIKA, one of the most used EAS simulators. This new computational tool allows us to analyze the effects that the propagation of heavy hadrons has in the EAS development.

  9. APPLICATION OF THE EXPOSURE DOSE ESTIMATING MODEL (ERDEM) TO ASSESSMENT OF DERMAL EXPOSURE IN THE RAT TO MALATHION

    EPA Science Inventory

    APPLICATION OF THE EXPOSURE DOSE ESTIMATING MODEL (ERDEM) TO ASSESSMENT OF DERMAL EXPOSURE IN THE RAT TO MALATHION.
    Evans, M.V1., Power, F.W2., Dary, C.C2., Tornero-Velez, R2., and Blancato, J.N2.
    1 NHEERL, US EPA, ORD, ETD, RTP, NC; 2 NERL, US EPA, ORD, EDRB, LV, NV
    Re...

  10. MODELING POPULATION EXPOSURES TO OUTDOOR SOURCES OF HAZARDOUS AIR POLLUTANTS

    EPA Science Inventory

    Accurate assessment of human exposures is an important part of environmental health effects research. However, most air pollution epidemiology studies rely upon imperfect surrogates of personal exposures, such as information based on available central-site outdoor concentration ...

  11. Implementation and validation of a modeling framework to assess personal exposure to black carbon.

    PubMed

    Dons, Evi; Van Poppel, Martine; Kochan, Bruno; Wets, Geert; Int Panis, Luc

    2014-01-01

    Because people tend to move from one place to another during the day, their exposure to air pollution will be determined by the concentration at each location combined with the exposure encountered in transport. In order to estimate the exposure of individuals in a population more accurately, the activity-based modeling framework for Black Carbon exposure assessment, AB(2)C, was developed. An activity-based traffic model was applied to model the whereabouts of individual agents. Exposure to black carbon (BC) in different microenvironments is assessed with a land use regression model, combined with a fixed indoor/outdoor factor for exposure in indoor environments. To estimate exposure in transport, a separate model was used taking into account transport mode, timing of the trip and degree of urbanization. The modeling framework is validated using weeklong time-activity diaries and BC exposure as revealed from a personal monitoring campaign with 62 participants. For each participant in the monitoring campaign, a synthetic population of 100 model-agents per day was made up with all agents meeting similar preconditions as each real-life agent. When these model-agents pass through every stage of the modeling framework, it results in a distribution of potential exposures for each individual. The AB(2)C model estimates average personal exposure slightly more accurately compared to ambient concentrations as predicted for the home subzone; however the added value of a dynamic model lies in the potential for detecting short term peak exposures rather than modeling average exposures. The latter may bring new opportunities to epidemiologists: studying the effect of frequently repeated but short exposure peaks on long term exposure and health. PMID:24161448

  12. Benchmarking of computer codes and approaches for modeling exposure scenarios

    SciTech Connect

    Seitz, R.R.; Rittmann, P.D.; Wood, M.I.; Cook, J.R.

    1994-08-01

    The US Department of Energy Headquarters established a performance assessment task team (PATT) to integrate the activities of DOE sites that are preparing performance assessments for the disposal of newly generated low-level waste. The PATT chartered a subteam with the task of comparing computer codes and exposure scenarios used for dose calculations in performance assessments. This report documents the efforts of the subteam. Computer codes considered in the comparison include GENII, PATHRAE-EPA, MICROSHIELD, and ISOSHLD. Calculations were also conducted using spreadsheets to provide a comparison at the most fundamental level. Calculations and modeling approaches are compared for unit radionuclide concentrations in water and soil for the ingestion, inhalation, and external dose pathways. Over 30 tables comparing inputs and results are provided.

  13. Predictive Modeling of Terrestrial Radiation Exposure from Geologic Materials

    SciTech Connect

    Malchow, Russell L.; Haber, Daniel University of Nevada, Las Vegas; Burnley, Pamela; Marsac, Kara; Hausrath, Elisabeth; Adcock, Christopher

    2015-01-01

    Aerial gamma ray surveys are important for those working in nuclear security and industry for determining locations of both anthropogenic radiological sources and natural occurrences of radionuclides. During an aerial gamma ray survey, a low flying aircraft, such as a helicopter, flies in a linear pattern across the survey area while measuring the gamma emissions with a sodium iodide (NaI) detector. Currently, if a gamma ray survey is being flown in an area, the only way to correct for geologic sources of gamma rays is to have flown the area previously. This is prohibitively expensive and would require complete national coverage. This project’s goal is to model the geologic contribution to radiological backgrounds using published geochemical data, GIS software, remote sensing, calculations, and modeling software. K, U and Th are the three major gamma emitters in geologic material. U and Th are assumed to be in secular equilibrium with their daughter isotopes. If K, U, and Th abundance values are known for a given geologic unit the expected gamma ray exposure rate can be calculated using the Grasty equation or by modeling software. Monte Carlo N-Particle Transport software (MCNP), developed by Los Alamos National Laboratory, is modeling software designed to simulate particles and their interactions with matter. Using this software, models have been created that represent various lithologies. These simulations randomly generate gamma ray photons at energy levels expected from natural radiologic sources. The photons take a random path through the simulated geologic media and deposit their energy at the end of their track. A series of nested spheres have been created and filled with simulated atmosphere to record energy deposition. Energies deposited are binned in the same manner as the NaI detectors used during an aerial survey. These models are used in place of the simplistic Grasty equation as they take into account absorption properties of the lithology which the

  14. Interior view of shower room 216 with original marble surround ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view of shower room 2-16 with original marble surround and double sash windows, facing east. - Marine Barracks, Panama Canal, Barracks Building, 100' North of Thatcher Highway, Balboa, Former Panama Canal Zone, CZ

  15. Men's shower room at east end of the building ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Men's shower room at east end of the building - Fitzsimons General Hospital, Swimming Pool, Southeast corner of East Nineteenth Place (formerly East McAfee Avenue) & Wheeling Street (formerly South Van Valzah Street), Aurora, Adams County, CO

  16. 10. NEEDLE SHOWER IN COOLING ROOM. Hot Springs National ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. NEEDLE SHOWER IN COOLING ROOM. - Hot Springs National Park, Bathhouse Row, Fordyce Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

  17. 9. NEEDLE SHOWER IN MEN'S PACK ROOM. Hot Springs ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. NEEDLE SHOWER IN MEN'S PACK ROOM. - Hot Springs National Park Bathhouse Row, Maurice Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

  18. Test results of a shower water recovery system

    NASA Technical Reports Server (NTRS)

    Verostko, Charles E.; Price, Donald F.; Garcia, Rafael; Pierson, Duane L.; Sauer, Richard L.

    1987-01-01

    A shower test was conducted recently at NASA-JSC in which waste water was reclaimed and reused. Test subjects showered in a prototype whole body shower following a protocol similar to that anticipated for Space Station. The waste water was purified using reverse osmosis followed by filtration through activated carbon and ion exchange resin beds. The reclaimed waste water was maintained free of microorganisms by using both heat and iodine. This paper discusses the test results, including the limited effectiveness of using iodine as a disinfectant and the evaluation of a Space Station candidate soap for showering. In addition, results are presented on chemical and microbial impurity content of water samples obtained from various locations in the water recovery process.

  19. Interior view of bath 1 showing original tub and shower ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view of bath 1 showing original tub and shower stall, facing southwest. - Albrook Air Force Station, Field Officer's Quarters, West side of Dargue Avenue Circle, Balboa, Former Panama Canal Zone, CZ

  20. FACILITY 846, TOILET AND SHOWER WINGS, QUADRANGLE J, OBLIQUE VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 846, TOILET AND SHOWER WINGS, QUADRANGLE J, OBLIQUE VIEW FACING WEST. - Schofield Barracks Military Reservation, Quadrangles I & J Barracks Type, Between Wright-Smith & Capron Avenues near Williston Avenue, Wahiawa, Honolulu County, HI

  1. Determination of the structure of meteor showers from radar observations.

    NASA Astrophysics Data System (ADS)

    Kolomiets, S. V.; Milyutchenko, I. A.

    1995-08-01

    A method for the determination of the parameter s for meteor mass distribution and meteor shower number density from radar measurements of meteor quantities during shower activities is considered. The data from radar observations of η Aquarids and Orionids in Khar'kov in 1986 are analyzed with this method. For the duration of both showers, the maximum activity of the parameter s is found to be equal to 1.65. The dependencies of the number densities of the meteor showers and of the parameter s on the solar longitude and the time of observation are also derived. The mean number density of meteor bodies with M ≥ 10-3g is equal to 2.9×10-11m-2s-1 for the η Aquarids and 2.5×10-11m-2s-1 for the Orionids.

  2. "Shower head" water connection for servicing railroad locomotives, perspective view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "Shower head" water connection for servicing railroad locomotives, perspective view looking NW across ATSF railyard. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  3. 61. SOUTH PLANT ETHYLENE GENERATOR BUILDING, WITH EMERGENCY SHOWER AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. SOUTH PLANT ETHYLENE GENERATOR BUILDING, WITH EMERGENCY SHOWER AT LEFT FOREGROUND. VIEW TO WEST. - Rocky Mountain Arsenal, Bounded by Ninety-sixth Avenue & Fifty-sixth Avenue, Buckley Road, Quebec Street & Colorado Highway 2, Commerce City, Adams County, CO

  4. Martian Atmospheric Methane Plumes from Meteor Shower Infall: A Hypothesis

    NASA Astrophysics Data System (ADS)

    Fries, M.; Christou, A.; Archer, D.; Conrad, P.; Cooke, W.; Eigenbrode, J.; ten Kate, I. L.; Matney, M.; Niles, P.; Sykes, M.; Steele, A.; Treiman, A.

    2016-09-01

    Methane plumes in the martian atmosphere were previously reported, but their source remains a mystery. We hypothesize a meteor shower source, as we find a correlation between Mars/cometary orbit encounters and detections of plumes.

  5. 10. NEEDLE SHOWER IN WOMEN'S PACK ROOM. Hot Springs ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. NEEDLE SHOWER IN WOMEN'S PACK ROOM. - Hot Springs National Park, Bathhouse Row, Lamar Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

  6. AMBIENT PARTICULATE MATTER EXPOSURES: A COMPARISON OF SHEDS-PM EXPOSURE MODEL PREDICTIONS AND ESTIMATES DERIVED FROM MEASUREMENTS COLLECTED DURING NERL'S RTP PM PANEL STUDY

    EPA Science Inventory

    The US EPA National Exposure Research Laboratory (NERL) is currently refining and evaluating a population exposure model for particulate matter (PM), called the Stochastic Human Exposure and Dose Simulation (SHEDS-PM) model. The SHEDS-PM model estimates the population distribu...

  7. TREXMO: A Translation Tool to Support the Use of Regulatory Occupational Exposure Models.

    PubMed

    Savic, Nenad; Racordon, Dimitri; Buchs, Didier; Gasic, Bojan; Vernez, David

    2016-10-01

    Occupational exposure models vary significantly in their complexity, purpose, and the level of expertise required from the user. Different parameters in the same model may lead to different exposure estimates for the same exposure situation. This paper presents a tool developed to deal with this concern-TREXMO or TRanslation of EXposure MOdels. TREXMO integrates six commonly used occupational exposure models, namely, ART v.1.5, STOFFENMANAGER(®) v.5.1, ECETOC TRA v.3, MEASE v.1.02.01, EMKG-EXPO-TOOL, and EASE v.2.0. By enabling a semi-automatic translation between the parameters of these six models, TREXMO facilitates their simultaneous use. For a given exposure situation, defined by a set of parameters in one of the models, TREXMO provides the user with the most appropriate parameters to use in the other exposure models. Results showed that, once an exposure situation and parameters were set in ART, TREXMO reduced the number of possible outcomes in the other models by 1-4 orders of magnitude. The tool should manage to reduce the uncertain entry or selection of parameters in the six models, improve between-user reliability, and reduce the time required for running several models for a given exposure situation. In addition to these advantages, registrants of chemicals and authorities should benefit from more reliable exposure estimates for the risk characterization of dangerous chemicals under Regulation, Evaluation, Authorisation and restriction of CHemicals (REACH). PMID:27358294

  8. Validation of Aircraft Noise Models at Lower Levels of Exposure

    NASA Technical Reports Server (NTRS)

    Page, Juliet A.; Plotkin, Kenneth J.; Carey, Jeffrey N.; Bradley, Kevin A.

    1996-01-01

    Noise levels around airports and airbases in the United States arc computed via the FAA's Integrated Noise Model (INM) or the Air Force's NOISEMAP (NMAP) program. These models were originally developed for use in the vicinity of airports, at distances which encompass a day night average sound level in decibels (Ldn) of 65 dB or higher. There is increasing interest in aircraft noise at larger distances from the airport. including en-route noise. To evaluate the applicability of INM and NMAP at larger distances, a measurement program was conducted at a major air carrier airport with monitoring sites located in areas exposed to an Ldn of 55 dB and higher. Automated Radar Terminal System (ARTS) radar tracking data were obtained to provide actual flight parameters and positive identification of aircraft. Flight operations were grouped according to aircraft type. stage length, straight versus curved flight tracks, and arrival versus departure. Sound exposure levels (SEL) were computed at monitoring locations, using the INM, and compared with measured values. While individual overflight SEL data was characterized by a high variance, analysis performed on an energy-averaging basis indicates that INM and similar models can be applied to regions exposed to an Ldn of 55 dB with no loss of reliability.

  9. Estimation of exposure to toxic releases using spatial interaction modeling

    PubMed Central

    2011-01-01

    Background The United States Environmental Protection Agency's Toxic Release Inventory (TRI) data are frequently used to estimate a community's exposure to pollution. However, this estimation process often uses underdeveloped geographic theory. Spatial interaction modeling provides a more realistic approach to this estimation process. This paper uses four sets of data: lung cancer age-adjusted mortality rates from the years 1990 through 2006 inclusive from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) database, TRI releases of carcinogens from 1987 to 1996, covariates associated with lung cancer, and the EPA's Risk-Screening Environmental Indicators (RSEI) model. Results The impact of the volume of carcinogenic TRI releases on each county's lung cancer mortality rates was calculated using six spatial interaction functions (containment, buffer, power decay, exponential decay, quadratic decay, and RSEI estimates) and evaluated with four multivariate regression methods (linear, generalized linear, spatial lag, and spatial error). Akaike Information Criterion values and P values of spatial interaction terms were computed. The impacts calculated from the interaction models were also mapped. Buffer and quadratic interaction functions had the lowest AIC values (22298 and 22525 respectively), although the gains from including the spatial interaction terms were diminished with spatial error and spatial lag regression. Conclusions The use of different methods for estimating the spatial risk posed by pollution from TRI sites can give different results about the impact of those sites on health outcomes. The most reliable estimates did not always come from the most complex methods. PMID:21418644

  10. 'Stoffenmanager', a web-based control banding tool using an exposure process model.

    PubMed

    Marquart, Hans; Heussen, Henri; Le Feber, Maaike; Noy, Dook; Tielemans, Erik; Schinkel, Jody; West, John; Van Der Schaaf, Doeke

    2008-08-01

    In the scope of a Dutch programme to reinforce the working conditions policy on hazardous substances, an internet-based tool was developed to help small- and medium-sized companies to handle hazardous substances with more care. The heart of this tool, called the Stoffenmanager, is a risk banding scheme. It combines a hazard banding scheme similar to that of COSHH Essentials and an exposure banding scheme based on an exposure model originally presented by Cherrie et al. (1996) and further developed by Cherrie and Schneider (1999). The exposure model has been modified to allow non-expert users to understand and use the model. Exposure scores are calculated based on categorization of determinants of emission, transmission and immission. These exposure scores are assigned to exposure bands. The comparison of exposure bands and hazard bands leads to a risk band or priority band. Following the evaluation of the priority of tasks done with products, generic exposure control measures can be evaluated for their possibility to lower the risks. Relevant control measures can be put into an action plan and into workplace instruction cards. The tool has several other functionalities regarding registration and storage of products. The exposure model in the Stoffenmanager leads to exposure scores. These have been compared with measured exposure levels. The exposure scores correlated well with measured exposure levels. The development of the Stoffenmanager has facilitated a whole range of further developments of useful tools for small- and medium-sized enterprises. PMID:18587140

  11. CAMS newly detected meteor showers and the sporadic background

    NASA Astrophysics Data System (ADS)

    Jenniskens, P.; Nénon, Q.; Gural, P. S.; Albers, J.; Haberman, B.; Johnson, B.; Morales, R.; Grigsby, B. J.; Samuels, D.; Johannink, C.

    2016-03-01

    The Cameras for Allsky Meteor Surveillance (CAMS) video-based meteoroid orbit survey adds 60 newly identified showers to the IAU Working List of Meteor Showers (numbers 427, 445-446, 506-507, and part of 643-750). 28 of these are also detected in the independent SonotaCo survey. In total, 230 meteor showers and shower components are identified in CAMS data, 177 of which are detected in at least two independent surveys. From the power-law size frequency distribution of detected showers, we extrapolate that 36% of all CAMS-observed meteors originated from ∼700 showers above the N = 1 per 110,000 shower limit. 71% of mass falling to Earth from streams arrives on Jupiter-family type orbits. The transient Geminids account for another 15%. All meteoroids not assigned to streams form a sporadic background with highest detected numbers from the apex source, but with 98% of mass falling in from the antihelion source. Even at large ∼7-mm sizes, a Poynting-Robertson drag evolved population is detected, which implies that the Grün et al. collisional lifetimes at these sizes are underestimated by about a factor of 10. While these large grains survive collisions, many fade on a 104-y timescale, possibly because they disintegrate into smaller particles by processes other than collisions, leaving a more resilient population to evolve. The meteors assigned to the various showers are identified in the CAMS Meteoroid Orbit Database 2.0 submitted to the IAU Meteor Data Center, and can be accessed also at

  12. Microwave detection of air showers with the MIDAS experiment

    NASA Astrophysics Data System (ADS)

    Privitera, Paolo; Alekotte, I.; Alvarez-Muñiz, J.; Berlin, A.; Bertou, X.; Bogdan, M.; Boháčová, M.; Bonifazi, C.; Carvalho, W. R.; de Mello Neto, J. R. T.; Facal San Luis, P.; Genat, J. F.; Hollon, N.; Mills, E.; Monasor, M.; Reyes, L. C.; Rouille d'Orfeuil, B.; Santos, E. M.; Wayne, S.; Williams, C.; Zas, E.

    2011-03-01

    Microwave emission from Extensive Air Showers could provide a novel technique for ultra-high energy cosmic rays detection over large area and with 100% duty cycle. We describe the design, performance and first results of the MIDAS (MIcrowave Detection of Air Showers) detector, a 4.5 m parabolic dish with 53 feeds in its focal plane, currently installed at the University of Chicago.

  13. Influence of meteor showers on Earth's upper atmosphere temperature

    NASA Astrophysics Data System (ADS)

    Salivonov, A.; Kozak, L.

    2005-04-01

    The warming of night atmosphere of the Earth during action of meteor showers is analyzed. It was used a satellite measurements in Earth's upper atmosphere for the period of 1993 in height range 85-130 km. Temperature values were obtained with the help of device WINDII (Wind Imaging Interferometer) installed on the America-French satellite UARS (Upper Atmosphere Research Satellite). The most intensive meteor showers Perseids, Leonids, Orionids and Geminids were considered.

  14. Multi-Year CMOR Observations of the Geminid Meteor Shower

    NASA Technical Reports Server (NTRS)

    Webster, A. R.; Jones, J.

    2011-01-01

    The three-station Canadian Meteor Orbit Radar (CMOR) is used here to examine the Geminid meteor shower with respect to variation in the stream properties including the flux and orbital elements over the period of activity in each of the consecutive years 2005 2008 and the variability from year to year. Attention is given to the appropriate choice and use of the D-criterion in the separating the shower meteors from the sporadic background.

  15. Modelling and simulation of concrete leaching under outdoor exposure conditions.

    PubMed

    Schiopu, Nicoleta; Tiruta-Barna, Ligia; Jayr, Emmanuel; Méhu, Jacques; Moszkowicz, Pierre

    2009-02-15

    Recently, a demand regarding the assessment of release of dangerous substances from construction products was raised by European Commission which has issued the Mandate M/366 addressed to CEN. This action is in relation with the Essential Requirement No. 3 "Hygiene, Health and Environment" of the Construction Products Directive (89/106/EC). The potential hazard for environment and health may arise in different life cycle stages of a construction product. During the service life stage, the release of substances due to contact with the rain water is the main potential hazard source, as a consequence of the leaching phenomenon. The objective of this paper is to present the development of a coupled chemical-transport model for the case of a concrete based construction product, i.e. concrete paving slabs, exposed to rain water under outdoor exposure conditions. The development of the model is based on an iterative process of comparing the experimental results with the simulated results up to an acceptable fit. The experiments were conducted at laboratory scale (equilibrium and dynamic leaching tests) and field scale. The product was exposed for one year in two types of leaching scenarios under outdoor conditions, "runoff" and "stagnation", and the element release was monitored. The model was calibrated using the experimental data obtained at laboratory scale and validated against measured field data, by taking into account the specific rain water balance and the atmospheric CO2 uptake as input parameters. The numerical tool used in order to model and simulate the leaching behaviour was PHREEQC, coupled with the Lawrence Livermore National Laboratory (LLNL) thermodynamic data base. The simulation results are satisfying and the paper demonstrates the feasibility of the modelling approach for the leaching behaviour assessment of concrete type construction materials. PMID:19118868

  16. Investigation of meteor shower parent bodies using various metrics

    NASA Astrophysics Data System (ADS)

    Dumitru, B. A.; Birlan, M.; Nedelcu, A.; Popescu, M.

    2016-01-01

    The present knowledge of meteor showers identifies the small bodies of our Solar System as supply sources for meteor streams. Both comets and asteroids are considered as the origin of meteor showers. The new paradigm of "active asteroids" opens up a large field of investigation regarding the relationships between asteroids and meteors. Processes like ejection and disaggregation at impacts, rotational instabilities, electrostatic repulsion, radiation pressure, dehydration stress followed by thermal fractures, sublimation of ices are sources of matter loss from asteroids. Our objective is to find genetic relationships between asteroids and meteor showers using metrics based on orbital elements. For this objective we selected three metrics (Southworth and Hawkins, 1963; Asher et al. 1993, and Jopek, 1993, respectively), the recent MPC database and the more recent IAU meteor shower database. From our analysis, 41 of the meteor showers have probabilities of being produced (or to be fueled) by asteroids. Our sample of asteroids contains more than 1000 objects, all of them belonging to the Near-Earth Asteroid population. The systematic approach performed, based on the physical properties of our sample, reinforced the link between asteroids and their associated meteor shower.

  17. Cosmogenic Nuclides in Metal and Stone Separates of an Antarctic L5/LL5 Chondrite Shower with a Large Pre-Atmospheric Size: QUE 90201

    NASA Technical Reports Server (NTRS)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.; Masarik, J.; Leya, I.; Wieler, R.

    2002-01-01

    Based on cosmogenic radionuclides in stone and metal fractions, we identified six members of a large Antarctic L5/LL5 chondrite shower. The radionuclides suggest a pre-atmospheric radius of 100-200 cm and a cosmic-ray exposure age of at least 5 Myr. Additional information is contained in the original extended abstract.

  18. Models of unexplained symptoms associated with occupational and environmental exposures.

    PubMed Central

    Spurgeon, Anne

    2002-01-01

    Unexplained illnesses characterized by nonspecific, multisystem complaints are often attributed to occupational or environmental chemical exposures. This raises difficulties for the regulatory authorities, who are frequently unable to agree on the existence, nature, or source of such illnesses. It is proposed that many of these difficulties derive from an adherence to a traditional medical model of disease and that the application of a biopsychosocial approach would be more effective for both research and individual case management. A number of models derived from the field of health psychology are discussed in terms of their application to occupational and environmental syndromes. A specific example is described that relates to the health problems experienced by sheep farmers in the United Kingdom who are exposed to organophosphate-based pesticides. The source of their complaints and the responses of the health professionals and the regulatory authorities are discussed within the context of a biopsychosocial approach that focuses on illness rather than on organic disease as the unit of study and explores the interaction between the various physical and psychosocial variables involved. It is proposed that this approach, which is already well established in the fields of human and social sciences, should be adopted more readily by those concerned with occupational and environmental epidemiology. PMID:12194893

  19. Applicability of western chemical dietary exposure models to the Chinese population.

    PubMed

    Zhao, Shizhen; Price, Oliver; Liu, Zhengtao; Jones, Kevin C; Sweetman, Andrew J

    2015-07-01

    A range of exposure models, which have been developed in Europe and North America, are playing an increasingly important role in priority setting and the risk assessment of chemicals. However, the applicability of these tools, which are based on Western dietary exposure pathways, to estimate chemical exposure to the Chinese population to support the development of a risk-based environment and exposure assessment, is unclear. Three frequently used modelling tools, EUSES, RAIDAR and ACC-HUMANsteady, have been evaluated in terms of human dietary exposure estimation by application to a range of chemicals with different physicochemical properties under both model default and Chinese dietary scenarios. Hence, the modelling approaches were assessed by considering dietary pattern differences only. The predicted dietary exposure pathways were compared under both scenarios using a range of hypothetical and current emerging contaminants. Although the differences across models are greater than those between dietary scenarios, model predictions indicated that dietary preference can have a significant impact on human exposure, with the relatively high consumption of vegetables and cereals resulting in higher exposure via plants-based foodstuffs under Chinese consumption patterns compared to Western diets. The selected models demonstrated a good ability to identify key dietary exposure pathways which can be used for screening purposes and an evaluative risk assessment. However, some model adaptations will be required to cover a number of important Chinese exposure pathways, such as freshwater farmed-fish, grains and pork.

  20. Measurements of the muon content of air showers at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Valiño, I.; Pierre Auger Collaboration

    2015-08-01

    The Pierre Auger Observatory offers a unique window to study cosmic rays and particle physics at energies above 3 EeV (corresponding to a centre-of-mass energy of 75 TeV in proton-proton collisions) inaccessible to accelerator experiments. We discuss the different methods of estimating the number of muons in showers recorded at the Pierre Auger Observatory, which is an observable sensitive to primary mass composition and to properties of the hadronic interactions in the shower. The muon content, derived from data with these methods, is presented and compared to predictions from the post-LHC hadronic interaction models for different primary composition. We find that models do not reproduce well the Auger observations, displaying a deficit of muons at the ground. In the light of these results, a better understanding of ultra-high energy extensive air showers and hadronic interactions is crucial to determine the composition of ultra-high energy cosmic rays. We report on the upgrade plans of the Pierre Auger Observatory to achieve this science goal.

  1. Meteorite Shower in Park Forest, Illinois

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2004-08-01

    Steven Simon (University of Chicago) and seven colleagues from the University of Chicago, the Planetary Studies Foundation, Harper College, Pacific Northwest National Lab, and the Field Museum in Chicago have classified the meteorite fragments that fell on Chicago's southern suburbs on the night of March 26, 2003. Described as ".. the most densely populated region to be hit by a meteorite shower in modern times," the village of Park Forest is at the center of the strewnfield and fortuitously also happens to be home to the Simon family, who answered scores of phone calls from neighboring meteorite finders. No injuries were reported though plenty of roofs, windows, walls, and cars were hit, and the police department took individual fusion-crusted fragments into custody as evidence. Its chemical and mineralogical compositions establish the Park Forest meteorite as an L5 chondrite, one of the most primitive groups of known meteorites. It is a strongly shocked monomict breccia (a term applied to a breccia made of one kind of rock) with light-colored clasts in a very dark matrix. The team measured cosmic radionuclides in Park Forest and found nearly zero cobalt-56 and high cobalt-60, values that indicate a large preatmospheric mass. They estimate the meteoroid was at least 900 kilograms and possibly as large as 7000 kilograms before it broke apart in the atmosphere, of which only about 30 kilograms of fragments have been recovered.

  2. Periodic cometary showers: Real or imaginary?

    NASA Technical Reports Server (NTRS)

    Grieve, R. A. F.; Sharpton, V. L.; Goodacre, A. K.; Garvin, J. B.

    1985-01-01

    Since the initial reports in 1980, a considerable body of chemical and physical evidence has been accumulated to indicate that a major impact event occurred on earth 65 million years ago. The effects of this event were global in extent and have been suggested as the cause of the sudden demise or mass extinction of a large percentage of life, including the dinosaurs, at the end of the geologic time period known as the Cretaceous. Recent statistical analyses of extinctions in the marine faunal record for the last 250 million years have suggested that mass extinctions may occur with a periodicity of every 26 to 30 million years. Following these results, other workers have attempted to demonstrate that these extinction events, like that at the end of the Cretaceous, are temporally correlated with large impact events. A recent scenario suggests that they are the result of periodic showers of comets produced by either the passage of the solar system through the galactic plane or by perturbations of the cometary cloud in the outer solar system by a, as yet unseen, solar companion. This hypothesized solar companion has been given the name Nemesis.

  3. IN-RESIDENCE, MULTIPLE ROUTE EXPOSURES TO CHLORPYRIFOS AND DIAZINON ESTIMATED BY INDIRECT METHOD MODELS

    EPA Science Inventory

    One of the objectives of the National Human Exposure Assessment Survey (NHEXAS) is to estimate exposures to several pollutants in multiple media and determine their distributions for the population of Arizona. This paper presents modeling methods used to estimate exposure dist...

  4. ANALYSIS OF HUMAN ACTIVITY DATA FOR USE IN MODELING ENVIRONMENTAL EXPOSURES

    EPA Science Inventory

    Human activity data are a critical part of exposure models being developed by the US EPA's National Exposure Research Laboratory (NERL). An analysis of human activity data within NERL's Consolidated Human Activity Database (CHAD) was performed in two areas relevant to exposure ...

  5. Strategies for Controlling Item Exposure in Computerized Adaptive Testing with the Generalized Partial Credit Model

    ERIC Educational Resources Information Center

    Davis, Laurie Laughlin

    2004-01-01

    Choosing a strategy for controlling item exposure has become an integral part of test development for computerized adaptive testing (CAT). This study investigated the performance of six procedures for controlling item exposure in a series of simulated CATs under the generalized partial credit model. In addition to a no-exposure control baseline…

  6. UNCERTAINTY ANALYSIS OF TCE USING THE DOSE EXPOSURE ESTIMATING MODEL (DEEM) IN ACSL

    EPA Science Inventory

    The ACSL-based Dose Exposure Estimating Model(DEEM) under development by EPA is used to perform art uncertainty analysis of a physiologically based pharmacokinetic (PSPK) model of trichloroethylene (TCE). This model involves several circulating metabolites such as trichloroacet...

  7. Overview of EPA CSS Intramural Research on Life Cycle and Human Exposure Modeling

    EPA Science Inventory

    Improved human exposure modeling in life cycle assessmentsModeling and assessment for chemicals/products with less extensive dataMore rapid and higher throughput assessmentsLife Cycle-Human Exposure Modeling (LC-HEM) tool usable by Offices/Regions and by external stakeholders

  8. The Working Group on Meteor Showers Nomenclature: a History, Current Status and a Call for Contributions

    NASA Technical Reports Server (NTRS)

    Jopek, T. J.; Jenniskens, P. M.

    2011-01-01

    During the IAU General Assembly in Rio de Janeiro in 2009, the members of Commission 22 established the Working Group on Meteor Shower Nomenclature, from what was formerly the Task Group on Meteor Shower Nomenclature. The Task Group had completed its mission to propose a first list of established meteor showers that could receive officially names. At the business meeting of Commission 22 the list of 64 established showers was approved and consequently officially accepted by the IAU. A two-step process is adopted for showers to receive an official name from the IAU: i) before publication, all new showers discussed in the literature are first added to the Working List of Meteor Showers, thereby receiving a unique name, IAU number and three-letter code; ii) all showers which come up to the verification criterion are selected for inclusion in the List of Established Meteor Showers, before being officially named at the next IAU General Assembly.

  9. A study to improve the past orbit of comet C/1917 F1 (Mellish) on the basis of its observed meteor showers

    NASA Astrophysics Data System (ADS)

    Neslušan, L.; Vaubaillon, J.; Hajduková, M.

    2016-05-01

    Context. Periodic comets are known to be the parent bodies of meteoroid streams. The stream of a given comet can split into several filaments. These can be observed in the Earth's atmosphere as more than just a single meteor shower. One such comet is C/1917 F1 (Mellish), which associates at least two, possibly four, meteor showers that have been recorded in the meteor databases. In a recent study, the dynamical evolution of the C/1917 F1's theoretical stream was followed by only considering the gravitational perturbations. The properties of individual filaments of this stream, corresponding to the appropriate meteor showers, were not predicted perfectly. Aims: To reach better agreement between theory and observation, we repeatedly model the theoretical stream of C/1917 F1. In the modeling, we also include the Poynting-Robertson drag acting on meteoroids and assume an action of the non-gravitational effects on the parent comet dynamics. If success was achieved, the modeling could become a tool that would enable us to recover the past orbital history of the parent comet. Methods: Considering the nominal orbit, as well as several cloned orbits, of the comet C/1917 F1, we modeled its theoretical streams. The modeling was performed for several past perihelion passages. Each modeled stream consists of 10 000 test particles that are influenced by the Poynting-Robertson drag of various strengths. Results: We achieve a partial improvement in the prediction of the properties of all four meteor showers. The Poynting-Robertson drag helps to improve the match between the theory and observation of three of the four showers. However, when considering the nominal orbit of the parent comet, a perfect match seems to be impossible. A close match in the case of the most problematic shower is achieved using a cloned orbit, but this is not applicable to reality because the simultaneous predictions of the properties of the other three showers fail.

  10. THE CONTRIBUTION OF AMBIENT PM2.5 TO TOTAL PERSONAL EXPOSURES: RESULTS FROM A POPULATION EXPOSURE MODEL FOR PHILADELPHIA, PA

    EPA Science Inventory

    The US EPA National Exposure Research Laboratory (NERL) is currently developing an integrated human exposure source-to-dose modeling system (HES2D). This modeling system will incorporate population exposure modules that use a probabilistic approach to predict population exposu...

  11. SHEDS-PM: A POPULATION EXPOSURE MODEL FOR PREDICTING DISTRIBUTIONS OF PM EXPOSURE AND DOSE FROM BOTH OUTDOOR AND INDOOR SOURCES

    EPA Science Inventory

    The US EPA National Exposure Research Laboratory (NERL) has developed a population exposure and dose model for particulate matter (PM), called the Stochastic Human Exposure and Dose Simulation (SHEDS) model. SHEDS-PM uses a probabilistic approach that incorporates both variabi...

  12. MicroExposure Monte Carlo analysis modeling PCB exposures through fish ingestion from the Upper Hudson River

    SciTech Connect

    Ebert, E.S.; Price, P.S.; McCrodden, J.L.; Ducey, J.S.; Keenan, R.E.

    1995-12-31

    The risks associated with exposures to mixtures of polychlorinated biphenyls (PCBs) from the consumption of fish in the vicinity of Superfund sites traditionally have been evaluated by using simple algebraic equations to calculate the dose received by a highly successful angler. A Lifetime Average Daily Dose (LADD) is estimated using default assumptions concerning the quantity of fish consumed, an angler`s body weight, an angler`s exposure duration, and a static measure of PCB levels in fish. Recent changes in EPA`s policies and guidelines, however, have focused on improving the management of environmental risks by providing decision-makers with a distribution of possible risks rather than a single point estimate. MicroExposure Monte Carlo analysis is a recent development in probabilistic exposure assessment in which a LADD for a given angler is calculated as the sum of many individual doses received over the course of a lifetime from individual exposure events. Data on concentrations of PCBs in individual fish are thereby incorporated into the analysis as are other temporal changes in the various exposure parameters. In this paper, the MicroExposure Monte Carlo model is applied to characterize the distribution of PCB dose rates in a hypothetical population of recreational anglers who might potentially consume fish from the Upper Hudson River in the absence of a fishing ban. The analysis uses probabilistic techniques to account for temporal and age-related changes in exposure parameters and as a means of properly considering meal-to-meal variation in fish concentrations, cooking practices, and fish species.

  13. MIXED MODELS ANALYSIS OR URBANIZATION LEVEL ON CHLORPYRIFOS EXPOSURE

    EPA Science Inventory

    The National Human Exposure Assessment Survey (NHEXAS) pilot studies were conducted from 1995 through 1997 to examine human population exposure to a wide range of environmental contaminants. In one of the studies, NHEXAS-Maryland, a longitudinal design was used to repeatedly m...

  14. Exposure Modeling for Polychlorinated Biphenyls in School Buildings

    EPA Science Inventory

    There is limited research on characterizing exposures from PCB sources for occupants of school buildings. PCB measurement results from six schools were used to estimate potential exposure distributions for four age groups (4-5, 6-10, 11-14, 14-18 year-olds) using the Stochastic...

  15. CAREX Canada: an enhanced model for assessing occupational carcinogen exposure

    PubMed Central

    Peters, Cheryl E; Ge, Calvin B; Hall, Amy L; Davies, Hugh W; Demers, Paul A

    2015-01-01

    Objectives To estimate the numbers of workers exposed to known and suspected occupational carcinogens in Canada, building on the methods of CARcinogen EXposure (CAREX) projects in the European Union (EU). Methods CAREX Canada consists of estimates of the prevalence and level of exposure to occupational carcinogens. CAREX Canada includes occupational agents evaluated by the International Agency for Research on Cancer as known, probable or possible human carcinogens that were present and feasible to assess in Canadian workplaces. A Canadian Workplace Exposure Database was established to identify the potential for exposure in particular industries and occupations, and to create exposure level estimates among priority agents, where possible. CAREX EU data were reviewed for relevance to the Canadian context and the proportion of workers likely to be exposed by industry and occupation in Canada was assigned using expert assessment and agreement by a minimum of two occupational hygienists. These proportions were used to generate prevalence estimates by linkage with the Census of Population for 2006, and these estimates are available by industry, occupation, sex and province. Results CAREX Canada estimated the number of workers exposed to 44 known, probable and suspected carcinogens. Estimates of levels of exposure were further developed for 18 priority agents. Common exposures included night shift work (1.9 million exposed), solar ultraviolet radiation exposure (1.5 million exposed) and diesel engine exhaust (781 000 exposed). Conclusions A substantial proportion of Canadian workers are exposed to known and suspected carcinogens at work. PMID:24969047

  16. MODELING INHALATION AND MULTIMEDIA MULTIPATHWAY HUMAN EXPOSURES TO ENVIRONMENTAL POLLUTANTS

    EPA Science Inventory

    Estimation of exposures of children and adults to air toxics or multimedia pollutants require careful consideration of sources and concentrations of pollutants that may be present in different media, as well as various routes and pathways of exposures associated with age-specif...

  17. Evaluating environmental modeling and sampling data with biomarker data to identify sources and routes of exposure

    NASA Astrophysics Data System (ADS)

    Shin, Hyeong-Moo; McKone, Thomas E.; Bennett, Deborah H.

    2013-04-01

    Exposure to environmental chemicals results from multiple sources, environmental media, and exposure routes. Ideally, modeled exposures should be compared to biomonitoring data. This study compares the magnitude and variation of modeled polycyclic aromatic hydrocarbons (PAHs) exposures resulting from emissions to outdoor and indoor air and estimated exposure inferred from biomarker levels. Outdoor emissions result in both inhalation and food-based exposures. We modeled PAH intake doses using U.S. EPA's 2002 National Air Toxics Assessment (NATA) county-level emissions data for outdoor inhalation, the CalTOX model for food ingestion (based on NATA emissions), and indoor air concentrations from field studies for indoor inhalation. We then compared the modeled intake with the measured urine levels of hydroxy-PAH metabolites from the 2001-2002 National Health and Nutrition Examination Survey (NHANES) survey as quantifiable human intake of PAH parent-compounds. Lognormal probability plots of modeled intakes and estimated intakes inferred from biomarkers suggest that a primary route of exposure to naphthalene, fluorene, and phenanthrene for the U.S. population is likely inhalation from indoor sources. For benzo(a)pyrene, the predominant exposure route is likely from food ingestion resulting from multi-pathway transport and bioaccumulation due to outdoor emissions. Multiple routes of exposure are important for pyrene. We also considered the sensitivity of the predicted exposure to the proportion of the total naphthalene production volume emitted to the indoor environment. The comparison of PAH biomarkers with exposure variability estimated from models and sample data for various exposure pathways supports that both indoor and outdoor models are needed to capture the sources and routes of exposure to environmental contaminants.

  18. Uses and limits of empirical data in measuring and modeling human lead exposure.

    PubMed Central

    Mushak, P

    1998-01-01

    This paper examines the uses and limits of empirical data in evaluating measurement and modeling approaches to human lead exposure. Empirical data from experiment or observation or both have been used in studies of lead exposure. For example, experimental studies have elucidated and quantified physiologic or biokinetic parameters of lead exposure under controlled conditions. Observation, i.e., epidemiology, has been widely applied to study population exposures to lead. There is growing interest in the use of lead exposure prediction models and their evaluation before use in risk assessment. Empirical studies of lead exposure must be fully understood, especially their limits, before they are applied as "standards" or reference information for evaluation of exposure models, especially the U.S. Environmental Protection Agency's lead biokinetic model that is a focus of this article. Empirical and modeled datasets for lead exposure may not agree due to a) problems with the observational data or b) problems with the model; caution should be exercised before either a model or observational data are rejected. There are at least three sources of discordance in cases where there is lack of agreement: a) empirical data are accurate but the model is flawed; b) the model is valid but reference empirical data are inaccurate; or c) neither empirical data nor model is accurate, and each is inaccurate in different ways. This paper evaluates some of the critical empirical input to biokinetic models, especially lead bioavailability. Images Figure 3 PMID:9860906

  19. Showering behavior: implications for water and energy conservation

    SciTech Connect

    Rohles, F.H.; Konz, S.A.

    1982-01-01

    Three groups of subjects were selected to determine the amount and temperature of the water used when showering. The control group of 120 subjects (60 men and 60 women) was divided into four groups (15 men and 15 women) who, after showering, dressed in rooms whose temperatures were 18.3/sup 0/C (65 F) 21.1/sup 0/C (70 F) 23.9/sup 0/C (75 F) and 26.7/sup 0/C (80 F). The greatest amount of comfort after showering was experienced in the 26.7/sup 0/C (80 F) room. This group, who did not wash their hair while showering used a mean of 36 liters (9.2 gal) of water for their showers. A second group of subjects (12 men and 12 women), who did wash their hair, used 62 liters (16.4 gal); this represented an increase in water used by 78%. A third group (12 men and 12 women), who had their showers fitted with a shower head that restricted the flow-rate of water, used 24 liters (6.4 gal) or 30% less water. However, they set their water temperature at 41.1/sup 0/C (106 F) vs the 38.9/sup 0/C (102 F) setting of the other two groups. Implications of these findings are discussed in relation to both water and energy conservation and the amount of water used at different latitudes in the continental U.S. where the temperature of the water supply is different.

  20. On the age and parent body of the daytime Arietids meteor shower

    NASA Astrophysics Data System (ADS)

    Abedin, A.; Wiegert, P.; Pokorny, P.; Brown, P.

    2016-01-01

    The daytime Arietid meteor shower is active from mid-May to late June and is among the strongest of the annual meteor showers, comparable in activity and duration to the Perseids and the Geminids. Due to the daytime nature of the shower, the Arietids have mostly been constrained by radar studies. The Arietids exhibit a long-debated discrepancy in the semi-major axis and the eccentricity of meteoroid orbits as measured by radar and optical surveys. Radar studies yield systematically lower values for the semi-major axis and eccentricity, where the origin of these discrepancies remain unclear. The proposed parent bodies of the stream include comet 96P/Machholz and more recently the Marsden's group of sun-skirting comets. In this work, we present detailed numerical modelling of the daytime Arietid meteoroid stream, with the goal to identifying the parent body and constraining the age of the stream. We use observational data from an extensive survey of the Arietids by the Canadian Meteor Orbit Radar (CMOR), in the period of 2002-2013, and several optical observations by the SonotaCo meteor network and the Cameras for All-sky Meteor Surveillance (CAMS). Our simulations suggest that the age and observed characteristics of the daytime Arietids are consistent with cometary activity from 96P, over the past 12000 years. The sunskirting comets that presumably formed in a major comet breakup between 100 - 950 AD (Chodas and Sekanina, 2005), alone, cannot explain the observed shower characteristics of the Arietids. Thus, the Marsden sunskirters cannot be the dominant parent, though our simulations suggest that they contribute to the core of the stream.

  1. Ultra-High Energy Cosmic Rays: Composition, Early Air Shower Interactions, and Xmax Skewness

    NASA Astrophysics Data System (ADS)

    Stapleton, James

    The composition of Ultra-High Energy Cosmic Rays (UHECRs) is still not completely understood, and must be inferred from Extended Air Shower (EAS), particle cascades which they initiate upon entering the atmosphere. The atmospheric depth at which the shower contains the maximum number of particles ( Xmax) is the most composition-sensitive property of the air shower, but its interpretation is hindered by intrinsic statistical fluctuations in EAS development which cause distinct compositions to produce overlapping Xmax distributions as well as our limited knowledge at these energies of hadronic physics which strongly impacts the Xmax distribution's shape. These issues ultimately necessitate a variety of complementary approaches to interpreting UHECR composition from Xmax data. The current work advances these approaches by connecting X max skewness to the uncertainties above. The study of X max has historically focused only on the mean and standard deviation of its distribution, but skewness is shown here to be strongly related to both the statistical fluctuations in EAS development as well as the least-understood hadronic cross-sections in the air shower. This leads into a treatment of the Exponentially-Modified Gaussian (EMG) distribution, whose little-known properties make it very useful for Xmax analysis and for data analysis in general. A powerful method emerges which uses only descriptive statistics in a robust check for energy-dependent changes in UHECR mass or EAS development. The application of these analyses to X max data provides tantalizing clues concerning issues of critical importance, such as the relationship between Xmax and the 'ankle' break in the UHECR energy spectrum, or the inferred properties of the UHECR mass distribution and its strong dependence on hadronic model systematics.

  2. A likelihood method to cross-calibrate air-shower detectors

    NASA Astrophysics Data System (ADS)

    Dembinski, Hans Peter; Kégl, Balázs; Mariş, Ioana C.; Roth, Markus; Veberič, Darko

    2016-01-01

    We present a detailed statistical treatment of the energy calibration of hybrid air-shower detectors, which combine a surface detector array and a fluorescence detector, to obtain an unbiased estimate of the calibration curve. The special features of calibration data from air showers prevent unbiased results, if a standard least-squares fit is applied to the problem. We develop a general maximum-likelihood approach, based on the detailed statistical model, to solve the problem. Our approach was developed for the Pierre Auger Observatory, but the applied principles are general and can be transferred to other air-shower experiments, even to the cross-calibration of other observables. Since our general likelihood function is expensive to compute, we derive two approximations with significantly smaller computational cost. In the recent years both have been used to calibrate data of the Pierre Auger Observatory. We demonstrate that these approximations introduce negligible bias when they are applied to simulated toy experiments, which mimic realistic experimental conditions.

  3. Comparison of Modeling Approaches to Prioritize Chemicals Based on Estimates of Exposure and Exposure Potential

    EPA Science Inventory

    While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecologic...

  4. Chloramine-induced anaphylaxis while showering: a case report

    PubMed Central

    2012-01-01

    Introduction Sodium-N-chlorine-p-toluene sulfonamide, commonly known as chloramine-T, is a derivative of chlorine which is widely used as a disinfectant. For many years, chloramine-T has been described as a cause of immediate-type hypersensitivity, especially with regard to asthma and rhinitis, and as a cause of occupational dermatoses in cleaning personnel in hospitals, although no anaphylactic reaction has yet been reported. Hence, to the best of our knowledge we present the first case of anaphylaxis to chloramine-T with evidence of specific immunoglobulin E antibodies. Case presentation We describe the case of a 25-year-old Caucasian woman who was in good health and with a negative history for atopy, including no respiratory symptoms of rhinitis or asthma, and with no professional exposure to chloramine-T. She, while showering, applied a chloramine-T solution to a skin area with folliculitis on her leg, and within a few minutes developed generalized urticaria and angioedema, followed by vomiting and collapse with loss of consciousness. A skin prick test with a chloramine-T solution at 10mg/mL concentration was positive, and specific immunoglobulin E to chloramine-T was quantified at a value of 2.9 optical density as measured by the enzyme allergosorbent test technique. Conclusion The strict cause-effect relationship and the results of the skin test and the in vitro test make certain the causative role of chloramine-T in this case of anaphylaxis. This suggests that chloramine-T, based on its wide use as a disinfectant, should be considered a possible cause in anaphylaxis of unknown origin. PMID:23009577

  5. Combining regional- and local-scale air quality models with exposure models for use in environmental health studies.

    PubMed

    Isakov, Vlad; Touma, Jawad S; Burke, Janet; Lobdell, Danelle T; Palma, Ted; Rosenbaum, Arlene; Ozkaynak, Halûk

    2009-04-01

    Population-based human exposure models predict the distribution of personal exposures to pollutants of outdoor origin using a variety of inputs, including air pollution concentrations; human activity patterns, such as the amount of time spent outdoors versus indoors, commuting, walking, and indoors at home; microenvironmental infiltration rates; and pollutant removal rates in indoor environments. Typically, exposure models rely upon ambient air concentration inputs from a sparse network of monitoring stations. Here we present a unique methodology for combining multiple types of air quality models (the Community Multi-Scale Air Quality [CMAQ] chemical transport model added to the AERMOD dispersion model) and linking the resulting hourly concentrations to population exposure models (the Hazardous Air Pollutant Exposure Model [HAPEM] or the Stochastic Human Exposure and Dose Simulation [SHEDS] model) to enhance estimates of air pollution exposures that vary temporally (annual and seasonal) and spatially (at census-block-group resolution) in an urban area. The results indicate that there is a strong spatial gradient in the predicted mean exposure concentrations near roadways and industrial facilities that can vary by almost a factor of 2 across the urban area studied. At the high end of the exposure distribution (95th percentile), exposures are higher in the central district than in the suburbs. This is mostly due to the importance of personal mobility factors whereby individuals living in the central area often move between microenvironments with high concentrations, as opposed to individuals residing at the outskirts of the city. Also, our results indicate 20-30% differences due to commuting patterns and almost a factor of 2 difference because of near-roadway effects. These differences are smaller for the median exposures, indicating the highly variable nature of the reflected ambient concentrations. In conjunction with local data on emission sources

  6. Observing air showers from cosmic superluminal particles

    NASA Astrophysics Data System (ADS)

    Gonzalez-Mestres, Luis

    1998-06-01

    The Poincaré relativity principle has been tested at low energy with great accuracy, but its extrapolation to very high-energy phenomena is much less well established. Lorentz symmetry can be broken at Planck scale due to the renormalization of gravity or to some deeper structure of matter: we expect such a breaking to be a very high energy and very short distance phenomenon. If textbook special relativity is only an approximate property of the equations describing a sector of matter above some critical distance scale, an absolute local frame (the ``vacuum rest frame,'' VRF) can possibly be found and superluminal sectors of matter may exist related to new degrees of freedom not yet discovered experimentally. The new superluminal particles (``superbradyons,'' i.e. bradyons with superluminal critical speed) would have positive mass and energy, and behave kinematically like ``ordinary'' particles (those with critical speed in vacuum equal to c, the speed of light) apart from the difference in critical speed (we expect ci>>c, where ci is the critical speed of a superluminal sector). They may be the ultimate building blocks of matter. At speed v>c, they are expected to release ``Cherenkov'' radiation (``ordinary'' particles) in vacuum. Superluminal particles could provide most of the cosmic (dark) matter and produce very high-energy cosmic rays. We discuss: a) the possible relevance of superluminal matter to the composition, sources and spectra of high-energy cosmic rays; b) signatures and experiments allowing to possibly explore such effects. Very large volume and unprecedented background rejection ability are crucial requirements for any detector devoted to the search for cosmic superbradyons. Future cosmic-ray experiments using air-shower detectors (especially from space) naturally fulfil both requirements.

  7. Observing air showers from cosmic superluminal particles

    SciTech Connect

    Gonzalez-Mestres, Luis

    1998-06-15

    The Poincare relativity principle has been tested at low energy with great accuracy, but its extrapolation to very high-energy phenomena is much less well established. Lorentz symmetry can be broken at Planck scale due to the renormalization of gravity or to some deeper structure of matter: we expect such a breaking to be a very high energy and very short distance phenomenon. If textbook special relativity is only an approximate property of the equations describing a sector of matter above some critical distance scale, an absolute local frame (the 'vacuum rest frame', VRF) can possibly be found and superluminal sectors of matter may exist related to new degrees of freedom not yet discovered experimentally. The new superluminal particles ('superbradyons', i.e. bradyons with superluminal critical speed) would have positive mass and energy, and behave kinematically like 'ordinary' particles (those with critical speed in vacuum equal to c, the speed of light) apart from the difference in critical speed (we expect c{sub i}>>c, where c{sub i} is the critical speed of a superluminal sector). They may be the ultimate building blocks of matter. At speed v>c, they are expected to release ''Cherenkov'' radiation ('ordinary' particles) in vacuum. Superluminal particles could provide most of the cosmic (dark) matter and produce very high-energy cosmic rays. We discuss: a) the possible relevance of superluminal matter to the composition, sources and spectra of high-energy cosmic rays; b) signatures and experiments allowing to possibly explore such effects. Very large volume and unprecedented background rejection ability are crucial requirements for any detector devoted to the search for cosmic superbradyons. Future cosmic-ray experiments using air-shower detectors (especially from space) naturally fulfil both requirements.

  8. Evaluating indoor exposure modeling alternatives for LCA: A case study in the vehicle repair industry

    SciTech Connect

    Demou, Evangelia; Hellweg, Stefanie; Wilson, Michael P.; Hammond, S. Katharine; McKone, Thomas E.

    2009-05-01

    We evaluated three exposure models with data obtained from measurements among workers who use"aerosol" solvent products in the vehicle repair industry and with field experiments using these products to simulate the same exposure conditions. The three exposure models were the: 1) homogeneously-mixed-one-box model, 2) multi-zone model, and 3) eddy-diffusion model. Temporally differentiated real-time breathing zone volatile organic compound (VOC) concentration measurements, integrated far-field area samples, and simulated experiments were used in estimating parameters, such as emission rates, diffusivity, and near-field dimensions. We assessed differences in model input requirements and their efficacy for predictive modeling. The One-box model was not able to resemble the temporal profile of exposure concentrations, but it performed well concerning time-weighted exposure over extended time periods. However, this model required an adjustment for spatial concentration gradients. Multi-zone models and diffusion-models may solve this problem. However, we found that the reliable use of both these models requires extensive field data to appropriately define pivotal parameters such as diffusivity or near-field dimensions. We conclude that it is difficult to apply these models for predicting VOC exposures in the workplace. However, for comparative exposure scenarios in life-cycle assessment they may be useful.

  9. Modelling ecological and human exposure to POPs in Venice lagoon - Part II: Quantitative uncertainty and sensitivity analysis in coupled exposure models.

    PubMed

    Radomyski, Artur; Giubilato, Elisa; Ciffroy, Philippe; Critto, Andrea; Brochot, Céline; Marcomini, Antonio

    2016-11-01

    The study is focused on applying uncertainty and sensitivity analysis to support the application and evaluation of large exposure models where a significant number of parameters and complex exposure scenarios might be involved. The recently developed MERLIN-Expo exposure modelling tool was applied to probabilistically assess the ecological and human exposure to PCB 126 and 2,3,7,8-TCDD in the Venice lagoon (Italy). The 'Phytoplankton', 'Aquatic Invertebrate', 'Fish', 'Human intake' and PBPK models available in MERLIN-Expo library were integrated to create a specific food web to dynamically simulate bioaccumulation in various aquatic species and in the human body over individual lifetimes from 1932 until 1998. MERLIN-Expo is a high tier exposure modelling tool allowing propagation of uncertainty on the model predictions through Monte Carlo simulation. Uncertainty in model output can be further apportioned between parameters by applying built-in sensitivity analysis tools. In this study, uncertainty has been extensively addressed in the distribution functions to describe the data input and the effect on model results by applying sensitivity analysis techniques (screening Morris method, regression analysis, and variance-based method EFAST). In the exposure scenario developed for the Lagoon of Venice, the concentrations of 2,3,7,8-TCDD and PCB 126 in human blood turned out to be mainly influenced by a combination of parameters (half-lives of the chemicals, body weight variability, lipid fraction, food assimilation efficiency), physiological processes (uptake/elimination rates), environmental exposure concentrations (sediment, water, food) and eating behaviours (amount of food eaten). In conclusion, this case study demonstrated feasibility of MERLIN-Expo to be successfully employed in integrated, high tier exposure assessment. PMID:27432731

  10. Modelling ecological and human exposure to POPs in Venice lagoon - Part II: Quantitative uncertainty and sensitivity analysis in coupled exposure models.

    PubMed

    Radomyski, Artur; Giubilato, Elisa; Ciffroy, Philippe; Critto, Andrea; Brochot, Céline; Marcomini, Antonio

    2016-11-01

    The study is focused on applying uncertainty and sensitivity analysis to support the application and evaluation of large exposure models where a significant number of parameters and complex exposure scenarios might be involved. The recently developed MERLIN-Expo exposure modelling tool was applied to probabilistically assess the ecological and human exposure to PCB 126 and 2,3,7,8-TCDD in the Venice lagoon (Italy). The 'Phytoplankton', 'Aquatic Invertebrate', 'Fish', 'Human intake' and PBPK models available in MERLIN-Expo library were integrated to create a specific food web to dynamically simulate bioaccumulation in various aquatic species and in the human body over individual lifetimes from 1932 until 1998. MERLIN-Expo is a high tier exposure modelling tool allowing propagation of uncertainty on the model predictions through Monte Carlo simulation. Uncertainty in model output can be further apportioned between parameters by applying built-in sensitivity analysis tools. In this study, uncertainty has been extensively addressed in the distribution functions to describe the data input and the effect on model results by applying sensitivity analysis techniques (screening Morris method, regression analysis, and variance-based method EFAST). In the exposure scenario developed for the Lagoon of Venice, the concentrations of 2,3,7,8-TCDD and PCB 126 in human blood turned out to be mainly influenced by a combination of parameters (half-lives of the chemicals, body weight variability, lipid fraction, food assimilation efficiency), physiological processes (uptake/elimination rates), environmental exposure concentrations (sediment, water, food) and eating behaviours (amount of food eaten). In conclusion, this case study demonstrated feasibility of MERLIN-Expo to be successfully employed in integrated, high tier exposure assessment.

  11. Assessing exposure to allied ground troops in the Vietnam War: a quantitative evaluation of the Stellman Exposure Opportunity Index model.

    PubMed

    Ginevan, Michael E; Watkins, Deborah K; Ross, John H; O'Boyle, Randy A

    2009-06-01

    The Exposure Opportunity Index (EOI) is a proximity-based model developed to estimate relative exposure of ground troops in Vietnam to aerially applied herbicides. We conducted a detailed quantitative evaluation of the EOI model by using actual herbicide spray missions isolated in time and space. EOI scores were calculated for each of 36 hypothetical receptor location points associated with each spray mission for 30 herbicide missions for two time periods - day of herbicide application and day 2-3 post-application. Our analysis found an enormous range of EOI predictions with 500-1000-fold differences across missions directly under the flight path. This quantitative examination of the EOI suggests that extensive testing of the model's code is warranted. Researchers undertaking development of a proximity-based exposure model for epidemiologic studies of either Vietnam veterans or the Vietnamese population should conduct a thorough and realistic analysis of how precise and accurate the model results are likely to be and then assess whether the model results provide a useful basis for their planned epidemiologic studies.

  12. Assessing exposure to allied ground troops in the Vietnam War: a quantitative evaluation of the Stellman Exposure Opportunity Index model.

    PubMed

    Ginevan, Michael E; Watkins, Deborah K; Ross, John H; O'Boyle, Randy A

    2009-06-01

    The Exposure Opportunity Index (EOI) is a proximity-based model developed to estimate relative exposure of ground troops in Vietnam to aerially applied herbicides. We conducted a detailed quantitative evaluation of the EOI model by using actual herbicide spray missions isolated in time and space. EOI scores were calculated for each of 36 hypothetical receptor location points associated with each spray mission for 30 herbicide missions for two time periods - day of herbicide application and day 2-3 post-application. Our analysis found an enormous range of EOI predictions with 500-1000-fold differences across missions directly under the flight path. This quantitative examination of the EOI suggests that extensive testing of the model's code is warranted. Researchers undertaking development of a proximity-based exposure model for epidemiologic studies of either Vietnam veterans or the Vietnamese population should conduct a thorough and realistic analysis of how precise and accurate the model results are likely to be and then assess whether the model results provide a useful basis for their planned epidemiologic studies. PMID:19278712

  13. INTEGRATED PROBABILISTIC AND DETERMINISTIC MODELING TECHNIQUES IN ESTIMATING EXPOSURE TO WATER-BORNE CONTAMINANTS: PART 1 EXPOSURE MODELING

    EPA Science Inventory

    Exposure to contaminants originating in the domestic water supply is influenced by a number of factors, including human activities, water use behavior, and physical and chemical processes. The key role of human activities is very apparent in exposure related to volatile water-...

  14. A Neutron Burst Associated with an Extensive Air Shower?

    NASA Astrophysics Data System (ADS)

    Alves, Mauro; Martin, Inacio; Shkevov, Rumen; Gusev, Anatoly; De Abreu, Alessandro

    2016-07-01

    A portable and compact system based on a He-3 tube (LND, USA; model 25311) with an area of approximately 250 cm² and is used to record neutron count rates at ground level in the energy range of 0.025 eV to 10 MeV, in São José dos Campos, SP, Brazil (23° 12' 45" S, 45° 52' 00" W; altitude, 660m). The detector, power supply, digitizer and other hardware are housed in an air-conditioned room. The detector power supply and digitizer are not connected to the main electricity network; a high-capacity 12-V battery is used to power the detector and digitizer. Neutron counts are accumulated at 1-minute intervals continuously. The data are stored in a PC for further analysis. In February 8, 2015, at 12 h 22 min (local time) during a period of fair weather with minimal cloud cover (< 1 okta) the neutron detector recorded a sharp (count rate = 27 neutrons/min) and brief (< 1 min) increase in the count rate. In the days before and after this event, the neutron count rate has oscillated between 0 and 3 neutrons/min. Since the occurrence of this event is not related with spurious signals, malfunctioning equipment, oscillations in the mains voltage, etc. we are led to believe that the sharp increase was caused by a physical source such as a an extensive air shower that occurred over the detector.

  15. Prevention of intraoperative wound contamination with chlorhexidine shower and scrub.

    PubMed

    Garibaldi, R A

    1988-04-01

    In a prospective, controlled, clinical trial, we found that preoperative showering and scrubbing with 4% chlorhexidine gluconate was more effective than povidone-iodine or triclocarban medicated soap in reducing skin colonization at the site of surgical incision. Mean log colony counts of the incision site were one half to one log lower for patients who showered with chlorhexidine compared to those who showered with the other regimens. No growth was observed on 43% of the post shower skin cultures from patients in the chlorhexidine group compared with 16% of the cultures from patients who had povidone-iodine showers and 5% of those from patients who used medicated soap and water. The frequency of positive intraoperative wound cultures was 4% with chlorhexidine, 9% with povidone-iodine and 14% with medicated soap and water. This study demonstrates that chlorhexidine gluconate is a more effective skin disinfectant than either povidone-iodine or triclocarban soap and water and that its use is associated with lower rates of intraoperative wound contamination.

  16. Comparative analysis of showering protocols for mass-casualty decontamination.

    PubMed

    Amlot, Richard; Larner, Joanne; Matar, Hazem; Jones, David R; Carter, Holly; Turner, Elizabeth A; Price, Shirley C; Chilcott, Robert P

    2010-01-01

    A well-established provision for mass-casualty decontamination that incorporates the use of mobile showering units has been developed in the UK. The effectiveness of such decontamination procedures will be critical in minimizing or preventing the contamination of emergency responders and hospital infrastructure. The purpose of this study was to evaluate three empirical strategies designed to optimize existing decontamination procedures: (1) instructions in the form of a pictorial aid prior to decontamination; (2) provision of a washcloth within the showering facility; and (3) an extended showering period. The study was a three-factor, between-participants (or "independent") design with 90 volunteers. The three factors each had two levels: use of washcloths (washcloth/no washcloth), washing instructions (instructions/no instructions), and shower cycle duration (three minutes/six minutes). The effectiveness of these strategies was quantified by whole-body fluorescence imaging following application of a red fluorophore to multiple, discrete areas of the skin. All five showering procedures were relatively effective in removing the fluorophore "contaminant", but the use of a cloth (in the absence of instructions) led to a significant ( appox. 20%) improvement in the effectiveness of decontamination over the standard protocol (p <0.05). Current mass-casualty decontamination effectiveness, especially in children, can be optimized by the provision of a washcloth. This simple but effective approach indicates the value of performing controlled volunteer trials for optimizing existing decontamination procedures.

  17. Thickness of the particle swarm in cosmic ray air showers

    NASA Technical Reports Server (NTRS)

    Linsley, J.

    1985-01-01

    The average dispersion in arrival time of air shower particles detected with a scintillator at an impact parameter r is described with accuracy 5-10% by the empirical formula sigma = Sigma sub to (1+r/r sub t) sup b, where Sigma sub to = 2.6 ns, r sub t = 30m and b = (1.94 + or - .08) (0.39 + or - .06) sec Theta, for r 2 km, 10 to the 8th power E 10 to the 11th power GeV, and Theta 60 deg. (E is the primary energy and theta is the zenith angle). The amount of fluctuation in sigma sub t due to fluctuations in the level of origin and shower development is less than 20%. These results provide a basis for estimating the impact parameters of very larger showers with data from very small detector arrays (mini-arrays). The energy of such showers can then be estimated from the local particle density. The formula also provides a basis for estimating the angular resolution of air shower array-telescopes.

  18. Expected rates with mini-arrays for air showers

    NASA Technical Reports Server (NTRS)

    Hazen, W. E.

    1985-01-01

    As a guide in the design of mini-arrays used to exploit the Linsley effect in the study of air showers, it is useful to calculate the expected rates. The results can aid in the choice of detectors and their placement or in predicting the utility of existing detector systems. Furthermore, the potential of the method can be appraised for the study of large showers. Specifically, we treat the case of a mini-array of dimensions small enough compared to the distance of axes of showers of interest so that it can be considered a point detector. The input information is taken from the many previous studies of air showers by other groups. The calculations will give: (1) the expected integral rate, F(sigma, rho), for disk thickness, sigma, or rise time, t sub 1/2, with local particle density, rho, as a parameter; (2) the effective detection area A(N) with sigma (min) and rho (min) and rho (min) as parameters; (3) the expected rate of collection of data F sub L (N) versus shower size, N.

  19. Catalogue of Meteor Showers and Storms in Korean History

    NASA Astrophysics Data System (ADS)

    Ahn, Sang-Hyeon

    2004-03-01

    We present a more complete and accurate catalogue of astronomical records for meteor showers and meteor storms appeared in primary official Korean history books, such as Samguk-sagi, Koryo-sa, Seungjeongwon-ilgi, and Choson-Wangjo-Sillok. So far the catalogue made by Imoto and Hasegawa in 1958 has been widely used in the international astronomical society. The catalogue is based on a report by Sekiguchi in 1917 that is mainly based on secondary history books. We observed that the catalogue has a number of errors in either dates or sources of the records. We have thoroughly checked the primary official history books, instead of the secondary ones, in order to make a corrected and extended catalogue. The catalogue contains 25 records of meteor storms, four records of intense meteor-showers, and five records of usual showers in Korean history. We also find that some of those records seem to correspond to some presently active meteor showers such as the Leonids, the Perseids, and the ¥ç-Aquarids-Orionids pair. However, a large number of those records do not correspond to such present showers. This catalogue we obtained can be useful for various astrophysical studies in the future.

  20. Extreme atmospheric electron densities created by extensive air showers

    NASA Astrophysics Data System (ADS)

    Rutjes, Casper; Camporeale, Enrico; Ebert, Ute; Buitink, Stijn; Scholten, Olaf; Trinh, Gia

    2016-04-01

    A sufficient density of free electrons and strong electric fields are the basic requirements to start any electrical discharge. In the context of thunderstorm discharges it has become clear that in addition droplets and or ice particles are required to enhance the electric field to values above breakdown. In our recent study [1] we have shown that these three ingredients have to interplay to allow for lightning inception, triggered by an extensive air shower event. The extensive air showers are a very stochastic natural phenomenon, creating highly coherent bursts of extreme electron density in our atmosphere. Predicting these electron density bursts accurately one has to take the uncertainty of the input variables into account. To this end we use uncertainty quantification methods, like in [2], to post-process our detailed Monte Carlo extensive air shower simulations, done with the CORSIKA [3] software package, which provides an efficient and elegant way to determine the distribution of the atmospheric electron density enhancements. We will present the latest results. [1] Dubinova, A., Rutjes, C., Ebert, E., Buitink, S., Scholten, O., and Trinh, G. T. N. "Prediction of Lightning Inception by Large Ice Particles and Extensive Air Showers." PRL 115 015002 (2015) [2] G.J.A. Loeven, J.A.S. Witteveen, H. Bijl, Probabilistic collocation: an efficient nonintrusive approach for arbitrarily distributed parametric uncertainties, 45th AIAA Aerospace Sciences Meeting, Reno, Nevada, 2007, AIAA-2007-317 [3] Heck, Dieter, et al. CORSIKA: A Monte Carlo code to simulate extensive air showers. No. FZKA-6019. 1998.

  1. The activity of autumn meteor showers in 2006-2008

    NASA Astrophysics Data System (ADS)

    Kartashova, Anna

    2015-03-01

    The purpose of meteor observations in INASAN is the study of meteor showers, as the elements of the migrant substance of the Solar System, and estimation of risk of hazardous collisions of spacecrafts with the particles of streams. Therefore we need to analyze the meteor events with brightness of up to 8 m, which stay in meteoroid streams for a long time and can be a hazardous for the spacecraft. The results of our single station TV observations of autumn meteor showers for the period from 2006 to 2008 are presented. The high-sensitive hybrid camera (the system with coupled of the Image Intensifier) FAVOR with limiting magnitude for meteors about 9m. . .10m in the field of view 20 × 18 was used for observations. In 2006-2008 from October to November more than 3 thousand of meteors were detected, 65% from them have the brightness from 6m to 9m. The identification with autumn meteor showers (Orionids, Taurids, Draconids, Leonids) was carried out. In order to estimate the density of the influx of meteor matter to the Earth for these meteor showers the Index of meteor activity (IMA) was calculated. The IMA distribution for the period 2006 - 2008 is given. The distributions of autumn meteor showers (the meteors with brightness of up to 8 m) by stellar magnitude from 2006 to 2008 are also presented.

  2. A new tool for radiation exposure calculations in aircraft flights during disturbed solar activity periods

    NASA Astrophysics Data System (ADS)

    Paschalis, Pavlos; Tezari, Anastasia; Gerontidou, Maria; Mavromichalaki, Helen

    2016-04-01

    Galactic cosmic rays and solar energetic particles can penetrate the Earth's atmosphere and interact with its molecules, which can cause atmospheric showers of secondary particles that are detected by ground based neutron monitor detectors. The cascades are of great importance for the study of the radiation exposure of aircraft crews. A new Geant4 software application is presented based on DYASTIMA (Dynamic Atmospheric Shower Tracking Interactive Model Application), which calculates the effective dose that aviators may receive in different flight scenarios characterized by different altitudes and different flight routes, during quiet and disturbed solar and cosmic ray activity. The concept is based on Monte Carlo simulations by using phantoms for the aircraft and the aviator and experimenting with different shielding materials.

  3. Air Pollution Exposure Model for Individuals (EMI) in Health Studies

    EPA Science Inventory

    In health studies, traffic-related air pollution is associated with adverse respiratory effects. Due to cost and participant burden of personal measurements, health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect ...

  4. MODELING OF MACROSCALE AGRICULTURAL ELEMENTS IN PESTICIDE EXPOSURE

    EPA Science Inventory

    Yuma County, Arizona, is the site of year around agriculture. To understand the role of agricultural pesticide exposures experienced by children, urinary metabolite concentrations were compared with agricultural use of pesticides. The urinary metabolite and household data wer...

  5. Air Quality Modeling in Support of the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS)

    EPA Science Inventory

    A major challenge in traffic-related air pollution exposure studies is the lack of information regarding pollutant exposure characterization. Air quality modeling can provide spatially and temporally varying exposure estimates for examining relationships between traffic-related a...

  6. REAL-TIME MODELING OF MOTOR VEHICLE EMISSIONS FOR ESTIMATING HUMAN EXPOSURES NEAR ROADWAYS

    EPA Science Inventory

    The United States Environmental Protection Agency's (EPA) National Exposure Research Laboratory is developing a real-time model of motor vehicle emissions to improve the methodology for modeling human exposure to motor vehicle emissions. The overall project goal is to develop ...

  7. 78 FR 13338 - Exposure Modeling Public Meeting; Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-27

    ... AGENCY Exposure Modeling Public Meeting; Notice of Public Meeting AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: An Exposure Modeling Public Meeting (EMPM) will be held for one day on... Potomac Yard (North Building), Fourth Floor Conference Center (N-4830), 2777 S. Crystal Drive,...

  8. 77 FR 61604 - Exposure Modeling Public Meeting; Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-10

    ... AGENCY Exposure Modeling Public Meeting; Notice of Public Meeting AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: An Exposure Modeling Public Meeting (EMPM) will be held for one day on... Potomac Yard (South Building), Fourth Floor Conference Center (S-4370-80), 2777 S. Crystal...

  9. A Comparison of Exposure Control Procedures in CAT Systems Based on Different Measurement Models for Testlets

    ERIC Educational Resources Information Center

    Boyd, Aimee M.; Dodd, Barbara; Fitzpatrick, Steven

    2013-01-01

    This study compared several exposure control procedures for CAT systems based on the three-parameter logistic testlet response theory model (Wang, Bradlow, & Wainer, 2002) and Masters' (1982) partial credit model when applied to a pool consisting entirely of testlets. The exposure control procedures studied were the modified within 0.10 logits…

  10. A Comparison of Item Exposure Control Procedures with the Generalized Partial Credit Model

    ERIC Educational Resources Information Center

    Sanchez, Edgar Isaac

    2008-01-01

    To enhance test security of high stakes tests, it is vital to understand the way various exposure control strategies function under various IRT models. To that end the present dissertation focused on the performance of several exposure control strategies under the generalized partial credit model with an item pool of 100 and 200 items. These…

  11. Spallation backgrounds in Super-Kamiokande are made in muon-induced showers

    NASA Astrophysics Data System (ADS)

    Li, Shirley Weishi; Beacom, John F.

    2015-05-01

    Crucial questions about solar and supernova neutrinos remain unanswered. Super-Kamiokande has the exposure needed for progress, but detector backgrounds are a limiting factor. A leading component is the beta decays of isotopes produced by cosmic-ray muons and their secondaries, which initiate nuclear spallation reactions. Cuts of events after and surrounding muon tracks reduce this spallation decay background by ≃ 90 % (at a cost of ≃ 20 % deadtime), but its rate at 6-18 MeV is still dominant. A better way to cut this background was suggested in a Super-Kamiokande paper by Bays et al. [Phys. Rev. D 85, 052007 (2012)] on a search for the diffuse supernova neutrino background. They found that spallation decays above 16 MeV were preceded near the same location by a peak in the apparent Cherenkov light profile from the muon; a more aggressive cut was applied to a limited section of the muon track, leading to decreased background without increased deadtime. We put their empirical discovery on a firm theoretical foundation. We show that almost all spallation decay isotopes are produced by muon-induced showers and that these showers are rare enough and energetic enough to be identifiable. This is the first such demonstration for any detector. We detail how the physics of showers explains the peak in the muon Cherenkov light profile and other Super-K observations. Our results provide a physical basis for practical improvements in background rejection that will benefit multiple studies. For solar neutrinos, in particular, it should be possible to dramatically reduce backgrounds at energies as low as 6 MeV.

  12. The MIDAS experiment: MIcrowave Detection of Air Showers

    NASA Astrophysics Data System (ADS)

    Facal, Pedro; Bohacova, Martina; Monasor, Maria; Privitera, Paolo; Reyes, Luis C.; Williams, Cristopher

    2010-02-01

    Recent measurements suggest that extensive air showers initiated by high energy cosmic rays (above 1 EeV) emit signals in the microwave band of the EM spectrum caused by the collisions of the free-electrons with the atmospheric neutral molecules in the plasma produced by the passage of the shower. Such emission is isotropic and could allow the detection of air showers with 100% duty cycle and a calorimetric-like energy measurement - a significant improvement over current detection techniques. We have built a MIDAS prototype, which consists of a 4.5 m diameter antenna with a cluster of 55 feed-horns in the 4 GHz range, covering a 10^o x10^o field of view, with self-triggering capability. The details of the prototype and first results will be presented. )

  13. Comet showers as a cause of mass extinction

    NASA Technical Reports Server (NTRS)

    Hut, Piet; Alvarez, Walter; Elder, William P.; Kauffman, Erle G.; Hansen, Thor; Keller, Gerta; Shoemaker, Eugene M.; Weissman, Paul R.

    1987-01-01

    Three independent pieces of evidence supporting a connection between comet showers and clustering in terrestrial cratering and mass extinctions are presented. The temporal profile of a comet shower triggered by a star passing through the Oort cloud is calculated. Four weak peaks are found in the age of distribution of impact craters over the past 100 Myr, as well as two compact clusters of ages of impact glass broadly coincident with crater-age peaks. Recent paleontological observations are reviewed that indicate a stepwise character for some well-documented mass extinctions in the past 100 Myr which roughly coincide with three of the four peaks in crater ages and which have a duration compatible with comet shower predictions.

  14. Independent identification of meteor showers in EDMOND database

    NASA Astrophysics Data System (ADS)

    Rudawska, R.; Matlovič, P.; Tóth, J.; Kornoš, L.

    2015-12-01

    Cooperation and data sharing among national networks and International Meteor Organization Video Meteor Database (IMO VMDB) resulted in European viDeo MeteOr Network Database (EDMOND). The current version of the database (EDMOND 5.0) contains 144 749 orbits collected from 2001 to 2014. This paper presents the results obtained by a proposed new independent method of meteor showers identification, which is applied to the current version of the database (EDMOND 5.0). In the first step of the survey we used the DSH criterion to find groups around each meteor within the similarity threshold. Mean parameters of the groups were calculated and compared using a new function DX based on geocentric parameters (λ⊙, α, δ, and Vg). Similar groups were merged into final clusters (representing meteor showers), and compared with the IAU Meteor Data Center list of meteor showers.

  15. Clinical and pathological manifestations of cardiovascular disease in rat models: the influence of acute ozone exposure

    EPA Science Inventory

    This paper shows that rat models of cardiovascular diseases have differential degrees of underlying pathologies at a young age. Rodent models of cardiovascular diseases (CVD) and metabolic disorders are used for examining susceptibility variations to environmental exposures. How...

  16. USE OF PHARMACOKINETIC MODELS TO ASSESS OCCUPATIONAL AND RESIDENTIAL PESTICIDE EXPOSURE

    EPA Science Inventory

    Urinary biomarker measurements were analyzed using a dynamic pharmacokinetic model. The dynamic model provided the structure to link spot urine samples with corresponding exposure and absorbed dose. Data from both occupational and residential studies were analyzed. In the Agri...

  17. THE IMPORTANCE OF CONCURRENT MONITORING AND MODELING FOR UNDERSTANDING MERCURY EXPOSURE IN THE ENVIRONMENT

    EPA Science Inventory

    Understanding the cycling processes governing mercury exposure in the environment requires sufficient process-based modeling and monitoring data. Monitoring provides ambient concentration data for specific sample times and locations. Modeling provides a tool for investigating the...

  18. ADDRESSING HUMAN EXPOSURES TO AIR POLLUTANTS AROUND BUILDINGS IN URBAN AREAS WITH COMPUTATIONAL FLUID DYNAMICS MODELS

    EPA Science Inventory

    This paper discusses the status and application of Computational Fluid Dynamics (CFD) models to address challenges for modeling human exposures to air pollutants around urban building microenvironments. There are challenges for more detailed understanding of air pollutant sour...

  19. Aging comets and their meteor showers

    NASA Astrophysics Data System (ADS)

    Ye, Quan-Zhi

    2016-10-01

    Comets are thought to be responsible for the terrestrial accretion of water and organic materials. The aging of comets is one of the most critical yet poorly understood problems in planetary astronomy. Here we attack this problem by examining different parts of the cometary aging spectrum of Jupiter-family comets (JFCs), a group of comets that dominates the cometary influx in the near-Earth space, using both telescopic and meteor observations.We examine two representative JFCs and the population of dormant comets. At the younger end of the aging spectrum, we examine a moderately active JFC, 15P/Finlay, and review the puzzle of the non-detection of the associated Finlayid meteor shower. We find that, although having been behaved like a dying comet in the past several 102 years, 15P/Finlay does possess ability for energetic outbursts without a clear reason. Towards the more aged end of the spectrum, we examine a weakly active JFC, 209P/LINEAR. By bridging telescopic observations at visible and infrared wavelength, meteor observations and dynamical investigations, we find that 209P/LINEAR is indeed likely an aged yet long-lived comet. At the other end of the spectrum, we examine the population of dormant near-Earth comets, by conducting a comprehensive meteor-based survey looking for dormant comets that have recently been active. We find the lower limit of the dormant comet fraction in the near-Earth object (NEO) population to be 2.0 ± 1.7%. This number is at the lower end of the numbers found using dynamical and telescopic techniques, which may imply that a significant fraction of comets in the true JFC population are weakly active and are not yet detected.These results have revealed interesting diversities in dying or dead comets, both in their behaviors as well as their natures. An immediate quest in the understanding of cometary aging would be to examine a large number of dying or dead comets and understand their general characteristics.

  20. Development of Yangbajing air shower core detector for a new EAS hybrid experiment

    NASA Astrophysics Data System (ADS)

    Liu, Jin-Sheng; Huang, Jing; Chen, Ding; Zhang, Ying; Zhai, Liu-Ming; Chen, Xu; Hu, Xiao-Bin; Lin, Yu-Hui; Zhang, Xue-Yao; Feng, Cun-Feng; Jia, Huan-Yu; Zhou, Xun-Xiu; Danzengluobu; Chen, Tian-Lu; Li, Hai-Jin; Liu, Mao-Yuan; Yuan, Ai-Fang

    2015-08-01

    Aiming at the observation of cosmic-ray chemical composition in the “knee” energy region, we have been developing a new type of air-shower core detector (YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing (90.522° E, 30.102° N, 4300 m above sea level, atmospheric depth: 606 g/m2) in Tibet, China. YAC works together with the Tibet air-shower array (Tibet-III) and an underground water Cherenkov muon detector array (MD) as a hybrid experiment. Each YAC detector unit consists of lead plates of 3.5 cm thickness and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores. The burst size can be measured from 1 MIP (Minimum Ionization Particle) to 106 MIPs. The first phase of this experiment, named “YAC- I”, consists of 16 YAC detectors each with a size of 40 cm×50 cm and distributed in a grid with an effective area of 10 m2. YAC- I is used to check hadronic interaction models. The second phase of the experiment, called “YAC- II”, consists of 124 YAC detectors with coverage of about 500 m2. The inner 100 detectors of 80 cm×50 cm each are deployed in a 10×10 matrix with a 1.9 m separation; the outer 24 detectors of 100 cm×50 cm each are distributed around these to reject non-core events whose shower cores are far from the YAC- II array. YAC- II is used to study the primary cosmic-ray composition, in particular, to obtain the energy spectra of protons, helium and iron nuclei between 5×1013 eV and 1016 eV, covering the “knee” and also connected with direct observations at energies around 100 TeV. We present the design and performance of YAC- II in this paper. Supported by grants from the National Natural Science Foundation of China (11078002, 11275212, 11165013), the Chinese Academy of Sciences (H9291450S3, Y4293211S5) and the Knowledge Innovation Fund of Institute of High Energy Physics (IHEP), China (H95451D0U2, H8515530U1)

  1. Initiation-promotion model of tumor prevalence in mice from space radiation exposures.

    PubMed

    Cucinotta, F A; Wilson, J W

    1995-08-01

    Exposures in space consist of low-level background components from galactic cosmic rays (GCR), occasional intense-energetic solar-particle events, periodic passes through geomagnetic-trapped radiation, and exposure from possible onboard nuclear-propulsion engines. Risk models for astronaut exposure from such diverse components and modalities must be developed to assure adequate protection in future NASA missions. The low-level background exposures (GCR), including relativistic heavy ions (HZE), will be the ultimate limiting factor for astronaut career exposure. We consider herein a two-mutation, initiation-promotion, radiation-carcinogenesis model in mice in which the initiation stage is represented by a linear kinetics model of cellular repair/misrepair, including the track-structure model for heavy ion action cross-sections. The model is validated by comparison with the harderian gland tumor experiments of Alpen et al. for various ion beams. We apply the initiation-promotion model to exposures from galactic cosmic rays, using models of the cosmic-ray environment and heavy ion transport, and consider the effects of the age of the mice prior to and after the exposure and of the length of time in space on predictions of relative risk. Our results indicate that biophysical models of age-dependent radiation hazard will provide a better understanding of GCR risk than models that rely strictly on estimates of the initial slopes of these radiations.

  2. Initiation-promotion model of tumor prevalence in mice from space radiation exposures

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Wilson, J. W.

    1995-01-01

    Exposures in space consist of low-level background components from galactic cosmic rays (GCR), occasional intense-energetic solar-particle events, periodic passes through geomagnetic-trapped radiation, and exposure from possible onboard nuclear-propulsion engines. Risk models for astronaut exposure from such diverse components and modalities must be developed to assure adequate protection in future NASA missions. The low-level background exposures (GCR), including relativistic heavy ions (HZE), will be the ultimate limiting factor for astronaut career exposure. We consider herein a two-mutation, initiation-promotion, radiation-carcinogenesis model in mice in which the initiation stage is represented by a linear kinetics model of cellular repair/misrepair, including the track-structure model for heavy ion action cross-sections. The model is validated by comparison with the harderian gland tumor experiments of Alpen et al. for various ion beams. We apply the initiation-promotion model to exposures from galactic cosmic rays, using models of the cosmic-ray environment and heavy ion transport, and consider the effects of the age of the mice prior to and after the exposure and of the length of time in space on predictions of relative risk. Our results indicate that biophysical models of age-dependent radiation hazard will provide a better understanding of GCR risk than models that rely strictly on estimates of the initial slopes of these radiations.

  3. Initiation-promotion model of tumor prevalence in mice from space radiation exposures.

    PubMed

    Cucinotta, F A; Wilson, J W

    1995-08-01

    Exposures in space consist of low-level background components from galactic cosmic rays (GCR), occasional intense-energetic solar-particle events, periodic passes through geomagnetic-trapped radiation, and exposure from possible onboard nuclear-propulsion engines. Risk models for astronaut exposure from such diverse components and modalities must be developed to assure adequate protection in future NASA missions. The low-level background exposures (GCR), including relativistic heavy ions (HZE), will be the ultimate limiting factor for astronaut career exposure. We consider herein a two-mutation, initiation-promotion, radiation-carcinogenesis model in mice in which the initiation stage is represented by a linear kinetics model of cellular repair/misrepair, including the track-structure model for heavy ion action cross-sections. The model is validated by comparison with the harderian gland tumor experiments of Alpen et al. for various ion beams. We apply the initiation-promotion model to exposures from galactic cosmic rays, using models of the cosmic-ray environment and heavy ion transport, and consider the effects of the age of the mice prior to and after the exposure and of the length of time in space on predictions of relative risk. Our results indicate that biophysical models of age-dependent radiation hazard will provide a better understanding of GCR risk than models that rely strictly on estimates of the initial slopes of these radiations. PMID:7480628

  4. Estimating Margin of Exposure to Thyroid Peroxidase Inhibitors Using High-Throughput in vitro Data, High-Throughput Exposure Modeling, and Physiologically Based Pharmacokinetic/Pharmacodynamic Modeling.

    PubMed

    Leonard, Jeremy A; Tan, Yu-Mei; Gilbert, Mary; Isaacs, Kristin; El-Masri, Hisham

    2016-05-01

    Some pharmaceuticals and environmental chemicals bind the thyroid peroxidase (TPO) enzyme and disrupt thyroid hormone production. The potential for TPO inhibition is a function of both the binding affinity and concentration of the chemical within the thyroid gland. The former can be determined through in vitro assays, and the latter is influenced by pharmacokinetic properties, along with environmental exposure levels. In this study, a physiologically based pharmacokinetic (PBPK) model was integrated with a pharmacodynamic (PD) model to establish internal doses capable of inhibiting TPO in relation to external exposure levels predicted through exposure modeling. The PBPK/PD model was evaluated using published serum or thyroid gland chemical concentrations or circulating thyroxine (T4) and triiodothyronine (T3) hormone levels measured in rats and humans. After evaluation, the model was used to estimate human equivalent intake doses resulting in reduction of T4 and T3 levels by 10% (ED10) for 6 chemicals of varying TPO-inhibiting potencies. These chemicals were methimazole, 6-propylthiouracil, resorcinol, benzophenone-2, 2-mercaptobenzothiazole, and triclosan. Margin of exposure values were estimated for these chemicals using the ED10 and predicted population exposure levels for females of child-bearing age. The modeling approach presented here revealed that examining hazard or exposure alone when prioritizing chemicals for risk assessment may be insufficient, and that consideration of pharmacokinetic properties is warranted. This approach also provides a mechanism for integrating in vitro data, pharmacokinetic properties, and exposure levels predicted through high-throughput means when interpreting adverse outcome pathways based on biological responses. PMID:26865668

  5. Character of energy flow in air shower core

    NASA Technical Reports Server (NTRS)

    Mizushima, K.; Asakimori, K.; Maeda, T.; Kameda, T.; Misaki, Y.

    1985-01-01

    Energy per charged particle near the core of air showers was measured by 9 energy flow detectors, which were the combination of Cerenkov counters and scintillators. Energy per particle of each detector was normalized to energy at 2m from the core. The following results were obtained as to the energy flow: (1) integral frequency distribution of mean energy per particle (averaged over 9 detectors) is composed of two groups separated distinctly; and (2) showers contained in one group show an anisotropy of arrival direction.

  6. Test results on reuse of reclaimed shower water - A summary

    NASA Technical Reports Server (NTRS)

    Verostko, Charles E.; Garcia, Rafael; Sauer, Richard; Reysa, Richard P.; Linton, Arthur T.

    1989-01-01

    Results are presented from tests to evaluate a microgravity whole body shower and waste water recovery system design for possible use on the Space Station. Several water recovery methods were tested, including phase change distillation, a thermoelectric hollow fiber membrane evaporation subsystem, and a reverse osmosis dynamic membrane system. Consideration is given to the test hardware, the types of soaps evaluated, the human response to showering with reclaimed water, chemical treatment for microbial control, the procedures for providing hygienic water, and the quality of water produced by the systems. All three of the waste water recovery systems tested successfully produced reclaimed water for reuse.

  7. Detection of Upward Air Showers with the EUSO Experiments

    NASA Technical Reports Server (NTRS)

    Takahashi, Y.; Hillman, L.; Zuccaro, Al; Adams, J.; Cline, D.

    2003-01-01

    Upward-going showers in the atmosphere can be detected by an orbiting satellite with appropriate instrumentation. If the method only uses directional Cherenkov radiation, it is difficult to discriminate the red shower events from the background noises of very short pulse. A spectroscopic polychromatic optical design can intentionally blur the focusing of photons at shorter wavelengths (300 - 330 nm), spreading the image size to 2 x 2 or 3 x 3 pixels. False triggers due to random chance coincidence of noises can be drastically reduced with a spectroscopic polychromatic, refractive telescope.

  8. Modeling toxicity due to intermittent exposure of rainbow trout and common shiners to monochloramine

    SciTech Connect

    Meyer, J.S.; Gulley, D.D. . Dept. of Zoology and Physiology); Goodrich, M.S. ); Szmania, D.C.; Brooks, A.S. . Center for Great Lakes Studies)

    1995-01-01

    The authors evaluated the ability of three mathematical models to predict toxicity to common shiners and rainbow trout during intermittent (pulsed) exposures to monochloramine, based on data from continuous-exposure toxicity tests. If a power term for the exposure-water concentration was included in the models, a concentration x time (Cxt) model and the Mancini uptake-depuration model predicted pulse LC50s to within [+-]50% of the observed pulse LC50s, for the first four pulses in toxicity tests with 2-h pulse/22-h recovery cycles. Beyond the fourth pulse cycle, though, the pulse LC50s predicted using the Cxt model appeared to diverge considerably from the trend of the experimental pulse LC50s, partly because this model does not predict an incipient lethal level (C[sub ILL]) for either continuous or intermittent exposures. The Mancini model predicted the C[sub ILL] moderately well in the common shiner intermittent-exposure test but not in the rainbow trout intermittent-exposure test. The Breck three-dimensional damage-repair model did not predict pulse LC50 or C[sub ILL] values as well as did the other two models, probably because not enough partial-mortality data were available to parameterize the model adequately. Although the underlying processes appear to be more complex than what these simple models assume, the models may still be adequate for use in regulating a few pulse discharges of monochloramine.

  9. Modeling Of In-Vehicle Human Exposure to Ambient Fine Particulate Matter

    PubMed Central

    Liu, Xiaozhen; Frey, H. Christopher

    2012-01-01

    A method for estimating in-vehicle PM2.5 exposure as part of a scenario-based population simulation model is developed and assessed. In existing models, such as the Stochastic Exposure and Dose Simulation model for Particulate Matter (SHEDS-PM), in-vehicle exposure is estimated using linear regression based on area-wide ambient PM2.5 concentration. An alternative modeling approach is explored based on estimation of near-road PM2.5 concentration and an in-vehicle mass balance. Near-road PM2.5 concentration is estimated using a dispersion model and fixed site monitor (FSM) data. In-vehicle concentration is estimated based on air exchange rate and filter efficiency. In-vehicle concentration varies with road type, traffic flow, windspeed, stability class, and ventilation. Average in-vehicle exposure is estimated to contribute 10 to 20 percent of average daily exposure. The contribution of in-vehicle exposure to total daily exposure can be higher for some individuals. Recommendations are made for updating exposure models and implementation of the alternative approach. PMID:23101000

  10. Simulation of population-based commuter exposure to NO₂ using different air pollution models.

    PubMed

    Ragettli, Martina S; Tsai, Ming-Yi; Braun-Fahrländer, Charlotte; de Nazelle, Audrey; Schindler, Christian; Ineichen, Alex; Ducret-Stich, Regina E; Perez, Laura; Probst-Hensch, Nicole; Künzli, Nino; Phuleria, Harish C

    2014-05-12

    We simulated commuter routes and long-term exposure to traffic-related air pollution during commute in a representative population sample in Basel (Switzerland), and evaluated three air pollution models with different spatial resolution for estimating commute exposures to nitrogen dioxide (NO2) as a marker of long-term exposure to traffic-related air pollution. Our approach includes spatially and temporally resolved data on actual commuter routes, travel modes and three air pollution models. Annual mean NO2 commuter exposures were similar between models. However, we found more within-city and within-subject variability in annual mean (±SD) NO2 commuter exposure with a high resolution dispersion model (40 ± 7 µg m(-3), range: 21-61) than with a dispersion model with a lower resolution (39 ± 5 µg m(-3); range: 24-51), and a land use regression model (41 ± 5 µg m(-3); range: 24-54). Highest median cumulative exposures were calculated along motorized transport and bicycle routes, and the lowest for walking. For estimating commuter exposure within a city and being interested also in small-scale variability between roads, a model with a high resolution is recommended. For larger scale epidemiological health assessment studies, models with a coarser spatial resolution are likely sufficient, especially when study areas include suburban and rural areas.

  11. Simulation of Population-Based Commuter Exposure to NO2 Using Different Air Pollution Models

    PubMed Central

    Ragettli, Martina S.; Tsai, Ming-Yi; Braun-Fahrländer, Charlotte; de Nazelle, Audrey; Schindler, Christian; Ineichen, Alex; Ducret-Stich, Regina E.; Perez, Laura; Probst-Hensch, Nicole; Künzli, Nino; Phuleria, Harish C.

    2014-01-01

    We simulated commuter routes and long-term exposure to traffic-related air pollution during commute in a representative population sample in Basel (Switzerland), and evaluated three air pollution models with different spatial resolution for estimating commute exposures to nitrogen dioxide (NO2) as a marker of long-term exposure to traffic-related air pollution. Our approach includes spatially and temporally resolved data on actual commuter routes, travel modes and three air pollution models. Annual mean NO2 commuter exposures were similar between models. However, we found more within-city and within-subject variability in annual mean (±SD) NO2 commuter exposure with a high resolution dispersion model (40 ± 7 µg m−3, range: 21–61) than with a dispersion model with a lower resolution (39 ± 5 µg m−3; range: 24–51), and a land use regression model (41 ± 5 µg m−3; range: 24–54). Highest median cumulative exposures were calculated along motorized transport and bicycle routes, and the lowest for walking. For estimating commuter exposure within a city and being interested also in small-scale variability between roads, a model with a high resolution is recommended. For larger scale epidemiological health assessment studies, models with a coarser spatial resolution are likely sufficient, especially when study areas include suburban and rural areas. PMID:24823664

  12. Modeling Tribal Exposures to PCBs from Fish Consumption

    EPA Science Inventory

    Studies have shown that U.S. population continues to be exposed to polychlorinated biphenyls (PCBs), despite the ban ~40 years ago. Fish intake is a major pathway, especially, for high fish-consumption groups. Exposure assessment and risk management considerations for tribal fish...

  13. BAYESIAN HIERARCHICAL MODELING OF PERSONAL EXPOSURE TO PARTICULATE MATTER

    EPA Science Inventory

    In the US EPA's 1998 Baltimore Epidemiology-Exposure Panel Study, a group of 21 residents of a single building retirement community wore personal monitors recording personal fine particulate air pollution concentrations (PM2.5) for 27 days, while other monitors recorde...

  14. Bayesian Hierarchical Modeling of Cardiac Response to Particulate Matter Exposure

    EPA Science Inventory

    Studies have linked increased levels of particulate air pollution to decreased autonomic control, as measured by heart rate variability (HRV), particularly in populations such as the elderly. In this study, we use data obtained from the 1998 USEPA epidemiology-exposure longitudin...

  15. Modeling tribal exposures to methyl mercury from fish consumption

    EPA Science Inventory

    Exposure assessment and risk management considerations for tribal fish consumption are different than for the general U.S. population because of higher fish intake from subsistence fishing and/or from unique cultural practices. This research summarizes analyses of available data ...

  16. In-residence, multiple route exposures to chlorpyrifos and diazinon estimated by indirect method models

    NASA Astrophysics Data System (ADS)

    Moschandreas, D. J.; Kim, Y.; Karuchit, S.; Ari, H.; Lebowitz, M. D.; O'Rourke, M. K.; Gordon, S.; Robertson, G.

    One of the objectives of the National Human Exposure Assessment Survey (NHEXAS) is to estimate exposures to several pollutants in multiple media and determine their distributions for the population of Arizona. This paper presents modeling methods used to estimate exposure distributions of chlorpyrifos and diazinon in the residential microenvironment using the database generated in Arizona (NHEXAS-AZ). A four-stage probability sampling design was used for sample selection. Exposures to pesticides were estimated using the indirect method of exposure calculation by combining measured concentrations of the two pesticides in multiple media with questionnaire information such as time subjects spent indoors, dietary and non-dietary items they consumed, and areas they touched. Most distributions of in-residence exposure to chlorpyrifos and diazinon were log-normal or nearly log-normal. Exposures to chlorpyrifos and diazinon vary by pesticide and route as well as by various demographic characteristics of the subjects. Comparisons of exposure to pesticides were investigated among subgroups of demographic categories, including gender, age, minority status, education, family income, household dwelling type, year the dwelling was built, pesticide use, and carpeted areas within dwellings. Residents with large carpeted areas within their dwellings have higher exposures to both pesticides for all routes than those in less carpet-covered areas. Depending on the route, several other determinants of exposure to pesticides were identified, but a clear pattern could not be established regarding the exposure differences between several subpopulation groups.

  17. Bisphenol A exposure pathways in early childhood: Reviewing the need for improved risk assessment models.

    PubMed

    Healy, Bridget F; English, Karin R; Jagals, Paul; Sly, Peter D

    2015-01-01

    Bisphenol A (BPA) is a plasticiser found in a number of household plastics, electronics, and food-packaging materials. Over the past 5 years, several human epidemiological studies have reported a positive association between BPA exposure and adverse health outcomes in children, including obesity, asthma, preterm birth, and neuro-behavioural disturbances. These findings are in conflict with international environmental risk assessment models, which predict daily exposure levels to BPA should not pose a risk to child health. The aim of this review is to provide an overview of the evidence for different exposure sources and potential exposure pathways of BPA in early childhood. By collating the findings from experimental models and exposure associations observed in human bio-monitoring studies, we affirm the potential for non-dietary sources to make a substantial contribution to total daily exposure in young children. Infants and toddlers have distinctive exposure sources, physiology, and metabolism of endocrine-disrupting chemicals. We recommend risk-assessment models implement new frameworks, which specifically address exposure and hazard in early childhood. This is particularly important for BPA, which is present in numerous products in the home and day-care environments, and for which animal studies report contradictory findings on its safety at environmentally relevant levels of exposure. PMID:26350983

  18. Sub-luminal pulses from cosmic ray air showers

    NASA Technical Reports Server (NTRS)

    Linsley, J.

    1985-01-01

    Some of the signals produced by air showers in scintillators possess a distinctive feature, a sub-luminal pulse (SLP) following the normal one with a time delay of approximately 1.5 r/c. The average amplitude of the SLP corresponds to an energy deposit of about 50 MeV, three times as much as is deposited in a typical scintillator by vertical minimum ionizing muons. The SLP account for approximately 5% of the energy deposited in the atmosphere by IR showers with energy 10 to the 10th power GeV at impact parameters 1 km. Assuming that these pulses are due to neutrons travelling with a speed slightly less than c, they provide a unique means of estimating E sub h, the energy deposited by slow hadrons, in showers of this very high energy. On the other hand, if not allowed for properly, these pulses are liable to cause errors in estimating the impact parameters of large showers from pulse width observations.

  19. BATH 1 SHOWING THE SHOWER ENCLOSURE AND FLUSH DOOR OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    BATH 1 SHOWING THE SHOWER ENCLOSURE AND FLUSH DOOR OF LINEN CLOSET. VIEW FACING SOUTH - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, U-Shaped Three-Bedroom Duplex Type 4, Acacia Road, Birch Circle, Cedar Drive and Elm Drive, Pearl City, Honolulu County, HI

  20. Muon spectrum in air showers initiated by gamma rays

    NASA Technical Reports Server (NTRS)

    Stephens, S. A.; Streitmatter, R. E.

    1985-01-01

    An analytic representation for the invariant cross-section for the production of charged pions in gamma P interactions was derived by using the available cross-sections. Using this the abundance of muons in a gamma ray initiated air shower is calculated.

  1. Ritualized Embarrassment at "Coed" Wedding and Baby Showers.

    ERIC Educational Resources Information Center

    Braithwaite, Dawn O.

    1995-01-01

    Finds that women embarrassed men at "coed" wedding and baby showers by teasing and causing them to look unpoised, and that men used avoidance, humor, remediation, and justification strategies. Adds a new strategy, compliance, to previous frameworks to explain males' reaction to embarrassment. Discusses the importance of context and degree of…

  2. The fast simulation of electromagnetic and hadronic showers

    SciTech Connect

    Grindhammer, G.; Rudowicz, M.; Peters, S.; Max-Planck-Institut fuer Physik und Astrophysik, Muenchen . Werner-Heisenberg-Inst. fuer Physik)

    1989-10-01

    A program for the fast simulation of electromagnetic and hadronic showers using parameterizations for the longitudinal and lateral profile is described. The fluctuations and correlations of the parameters are taken into account in a consistent way. Comparisons with data over a wide energy range are made. 15 refs., 17 figs.

  3. Matching tree-level matrix elements with interleaved showers

    NASA Astrophysics Data System (ADS)

    Lönnblad, Leif; Prestel, Stefan

    2012-03-01

    We present an implementation of the so-called Ckkw-l merging scheme for combining multi-jet tree-level matrix elements with parton showers. The implementation uses the transverse-momentum-ordered shower with interleaved multiple interactions as implemented in P YTHIA8. We validate our procedure using e+e--annihilation into jets and vector boson production in hadronic collisions, with special attention to details in the algorithm which are formally sub-leading in character, but may have visible effects in some observables. We find substantial merging scale dependencies induced by the enforced rapidity ordering in the default P YTHIA8 shower. If this rapidity ordering is removed the merging scale dependence is almost negligible. We then also find that the shower does a surprisingly good job of describing the hardness of multi-jet events, as long as the hardest couple of jets are given by the matrix elements. The effects of using interleaved multiple interactions as compared to more simplistic ways of adding underlying-event effects in vector boson production are shown to be negligible except in a few sensitive observables. To illustrate the generality of our implementation, we also give some example results from di-boson production and pure QCD jet production in hadronic collisions.

  4. Facility 171 Interior view of second floor shower room, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Facility 171 - Interior view of second floor shower room, showing original tile and metal ventilation louvers - U.S. Naval Base, Pearl Harbor, Latrine Dry Dock No. 2 & Latrine Dry Dock No.3, Near Avenue G adjacent to Dry Dock No. 2 & Dry Dock No. 3, Pearl City, Honolulu County, HI

  5. Sub-luminal pulses from cosmic ray air showers

    NASA Astrophysics Data System (ADS)

    Linsley, J.

    1985-08-01

    Some of the signals produced by air showers in scintillators possess a distinctive feature, a sub-luminal pulse (SLP) following the normal one with a time delay of approximately 1.5 r/c. The average amplitude of the SLP corresponds to an energy deposit of about 50 MeV, three times as much as is deposited in a typical scintillator by vertical minimum ionizing muons. The SLP account for approximately 5% of the energy deposited in the atmosphere by IR showers with energy 10 to the 10th power GeV at impact parameters 1 km. Assuming that these pulses are due to neutrons travelling with a speed slightly less than c, they provide a unique means of estimating Eh, the energy deposited by slow hadrons, in showers of this very high energy. On the other hand, if not allowed for properly, these pulses are liable to cause errors in estimating the impact parameters of large showers from pulse width observations.

  6. Radio Detection of Air Showers with LOFAR and AERA

    NASA Astrophysics Data System (ADS)

    Hörandel, Jörg R.

    Radio detection of extensive air showers is a new method to measure the properties of high-energy cosmic rays. Recent results are reviewed from the LOFAR radio telescope and the Auger Engineering Radio Array (AERA) at the Pierre Auger Observatory.

  7. Interior of decontamination area and shower at south entry, wood ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior of decontamination area and shower at south entry, wood door frame and shelf brackets in view, view facing south-southeast - U.S. Naval Base, Pearl Harbor, Operations & Message Center, Behind Facility No. 1, corner of Avenue E & Seventh Street, connected to Facility Nos. 1B & 1D by wooden bridges, Pearl City, Honolulu County, HI

  8. Air shower detectors in gamma-ray astronomy

    SciTech Connect

    Sinnis, Gus

    2008-01-01

    Extensive air shower (EAS) arrays directly detect the particles in an EAS that reach the observation altitude. This detection technique effectively makes air shower arrays synoptic telescopes -- they are capable of simultaneously and continuously viewing the entire overhead sky. Typical air shower detectors have an effective field-of-view of 2 sr and operate nearly 100% of the time. These two characteristics make them ideal instruments for studying the highest energy gamma rays, extended sources and transient phenomena. Until recently air shower arrays have had insufficient sensitivity to detect gamma-ray sources. Over the past decade, the situation has changed markedly. Milagro, in the US, and the Tibet AS{gamma} array in Tibet, have detected very-high-energy gamma-ray emission from the Crab Nebula and the active galaxy Markarian 421 (both previously known sources). Milagro has discovered TeV diffuse emission from the Milky Way, three unidentified sources of TeV gamma rays, and several candidate sources of TeV gamma rays. Given these successes and the suite of existing and planned instruments in the GeV and TeV regime (AGILE, GLAST, HESS, VERITAS, CTA, AGIS and IceCube) there are strong reasons for pursuing a next generation of EAS detectors. In conjunction with these other instruments the next generation of EAS instruments could answer long-standing problems in astrophysics.

  9. Visual data of minor meteor showers limits of the method

    NASA Technical Reports Server (NTRS)

    Rendtel, Jurgen; Koschack, R.

    1992-01-01

    Visual meteor observations are carried out on a regular basis by many experienced observers worldwide, thus supplying information about activity of meteor showers. The limits of the method are determined by the accuracy of the detection of the meteor trail. This study shows that visual meteor observations provide reliable data for an observable hourly rate of greater than or equal to 3.

  10. A (revised) confidence index for the forecasting of meteor showers

    NASA Astrophysics Data System (ADS)

    Vaubaillon, J.

    2016-01-01

    A confidence index for the forecasting of meteor showers is presented. The goal is to provide users with information regarding the way the forecasting is performed, so several degrees of confidence is achieved. This paper presents the meaning of the index coding system.

  11. Clustering of Hadronic Showers with a Structural Algorithm

    SciTech Connect

    Charles, M.J.; /SLAC

    2005-12-13

    The internal structure of hadronic showers can be resolved in a high-granularity calorimeter. This structure is described in terms of simple components and an algorithm for reconstruction of hadronic clusters using these components is presented. Results from applying this algorithm to simulated hadronic Z-pole events in the SiD concept are discussed.

  12. Large Deviation Analysis of Rapid Onset of Rain Showers.

    PubMed

    Wilkinson, Michael

    2016-01-01

    Rainfall from ice-free cumulus clouds requires collisions of large numbers of microscopic droplets to create every raindrop. The onset of rain showers can be surprisingly rapid, much faster than the mean time required for a single collision. Large-deviation theory is used to explain this observation. PMID:26799046

  13. Radio Emission in Atmospheric Air Showers Measured by LOPES-30

    SciTech Connect

    Isar, P. G.

    2008-01-24

    When Ultra High Energy Cosmic Rays (UHECR) interact with particles in the Earth's atmosphere, they produce a shower of secondary particles propagating towards the ground. These relativistic particles emit synchrotron radiation in the radio frequency range when passing the Earth's magnetic field. The LOPES (LOFAR Prototype Station) experiment investigates the radio emission from these showers in detail and will pave the way to use this detection technique for large scale applications like in LOFAR (Low Frequency Array) and the Pierre Auger Observatory. The LOPES experiment is co-located and measures in coincidence with the air shower experiment KASCADE-Grande at Forschungszentrum Karlsruhe, Germany. LOPES has an absolute amplitude calibration array of 30 dipole antennas (LOPES-30). After one year of measurements of the single East-West polarization by all 30 antennas, recently, the LOPES-30 set-up was configured to perform dual-polarization measurements. Half of the antennas have been configured for measurements of the North-South polarization. Only by measuring at the same time both, the E-W and N-S polarization components of the radio emission, the geo-synchrotron effect as the dominant emission mechanism in air showers can be verified. The status of the measurements, including the absolute calibration procedure of the dual-polarized antennas as well as analysis of dual-polarized event examples are reported.

  14. Large Deviation Analysis of Rapid Onset of Rain Showers.

    PubMed

    Wilkinson, Michael

    2016-01-01

    Rainfall from ice-free cumulus clouds requires collisions of large numbers of microscopic droplets to create every raindrop. The onset of rain showers can be surprisingly rapid, much faster than the mean time required for a single collision. Large-deviation theory is used to explain this observation.

  15. Large Deviation Analysis of Rapid Onset of Rain Showers

    NASA Astrophysics Data System (ADS)

    Wilkinson, Michael

    2016-01-01

    Rainfall from ice-free cumulus clouds requires collisions of large numbers of microscopic droplets to create every raindrop. The onset of rain showers can be surprisingly rapid, much faster than the mean time required for a single collision. Large-deviation theory is used to explain this observation.

  16. DEVELOMENT AND EVALUATION OF A MODEL FOR ESTIMATING LONG-TERM AVERAGE OZONE EXPOSURES TO CHILDREN

    EPA Science Inventory

    Long-term average exposures of school-age children can be modelled using longitudinal measurements collected during the Harvard Southern California Chronic Ozone Exposure Study over a 12-month period: June, 1995-May, 1996. The data base contains over 200 young children with perso...

  17. USE OF PBPK MODELING TO ASSESS CYPERMETHRIN EXPOSURE IN YOUNG AFTER A RESIDENTIAL APPLICATION

    EPA Science Inventory

    PBPK modeling was used to interpret exposure to cypermethrin among children in a small community of Jacksonville,FL. Sock loadings of cypermethin were used as a measure of exposure to cypermethrin. Urinary markers served as a measure of absorbed dose. In a comparison of presum...

  18. OZONE-INDUCED RESPIRATORY SYMPTOMS: EXPOSURE-RESPONSE MODELS AND ASSOCIATION WITH LUNG FUNCTION

    EPA Science Inventory

    Ozone-induced respiratory symptoms are known to be functions of concentration, minute ventilation, and duration of exposure. The purposes of this study were to identify an exposure-response model for symptoms, to determine whether response was related to age, and to assess the re...

  19. EPA's SHEDS-multimedia model: children's cumulative pyrethroid exposure estimates and evaluation against NHANES biomarker data

    EPA Science Inventory

    The U.S. EPA's SHEDS-Multimedia model was applied to enhance the understanding of children's exposures and doses to multiple pyrethroid pesticides, including major contributing chemicals and pathways. This paper presents combined dietary and residential exposure estimates and cum...

  20. A DYNAMIC NONLINEAR MODEL OF OZONE-INDUCED FEV1 RESPONSE UNDER CHANGING EXPOSURE CONDITIONS

    EPA Science Inventory

    A Dynamic Nonlinear Model of Ozone-induced FEV1 Response under Changing Exposure Conditions. 1WF McDonnell, 2PW Stewart, 3MV Smith. 1Human Studies Division, NHEERL, U.S. EPA, RTP, NC. 2University of North Carolina, Chapel Hill, NC. 3ASI, Durham, NC.

    Ozone exposure result...

  1. A Comparison of Exposure Control Procedures in CATs Using the 3PL Model

    ERIC Educational Resources Information Center

    Leroux, Audrey J.; Lopez, Myriam; Hembry, Ian; Dodd, Barbara G.

    2013-01-01

    This study compares the progressive-restricted standard error (PR-SE) exposure control procedure to three commonly used procedures in computerized adaptive testing, the randomesque, Sympson-Hetter (SH), and no exposure control methods. The performance of these four procedures is evaluated using the three-parameter logistic model under the…

  2. A Comparison of Exposure Control Procedures in CATS Using the GPC Model

    ERIC Educational Resources Information Center

    Leroux, Audrey J.; Dodd, Barbara G.

    2016-01-01

    The current study compares the progressive-restricted standard error (PR-SE) exposure control method with the Sympson-Hetter, randomesque, and no exposure control (maximum information) procedures using the generalized partial credit model with fixed- and variable-length CATs and two item pools. The PR-SE method administered the entire item pool…

  3. A NEW METHOD OF LONGITUDINAL DIARY ASSEMBLY FOR HUMAN EXPOSURE MODELING

    EPA Science Inventory

    Human exposure time-series modeling requires longitudinal time-activity diaries to evaluate the sequence of concentrations encountered, and hence, pollutant exposure for the simulated individuals. However, most of the available data on human activities are from cross-sectional su...

  4. Ocular exposure to UV-B in sunlight: the Melbourne visual impairment project model.

    PubMed

    McCarty, C A; Lee, S E; Livingston, P M; Bissinella, M; Taylor, H R

    1996-01-01

    Quantification of ocular exposure to ultraviolet-B radiation (UV-B) has become an important public health issue, with reports that the ozone layer is being depleted worldwide. Ocular exposure to UV-B is determined by ambient UV-B levels, the duration of outdoor exposure, the proportion of ambient UV-B that reaches the eye, and the use of ocular protection. We have developed a simplified model for quantifying lifetime ocular UV-B exposure that can be used in large epidemiological surveys. Exposure to UV-B is assessed and quantified using a model based on personal exposure over the six summer months. Data available for a population-based sample of 1150 people in the age range 40-98 years revealed a distribution in average annual lifetime ocular UV-B exposure similar to that reported in a previous study on which this model is based, and also demonstrate that people can recall lifetime personal behaviour related to ocular protection. It takes 12 minutes on average to collect these data. This model can be employed by researchers worldwide for uniform assessment of ocular UV-B exposure.

  5. Performance of a microenviromental model for estimating personal NO2 exposure in children

    NASA Astrophysics Data System (ADS)

    Mölter, Anna; Lindley, Sarah; de Vocht, Frank; Agius, Raymond; Kerry, Gina; Johnson, Katy; Ashmore, Mike; Terry, Andrew; Dimitroulopoulou, Sani; Simpson, Angela

    2012-05-01

    A common problem in epidemiological studies on air pollution is exposure misclassification, because investigators often assume exposure is equivalent to outdoor concentrations at participants' homes or at the nearest urban monitor. The aims of this study were: (1) to develop a new microenvironmental exposure model (MEEM), combining time-activity data with modelled outdoor and indoor NO2 concentrations; (2) to evaluate MEEM against data collected with Ogawa™ personal samplers (OPS); (3) to compare its performance against datasets typically used in epidemiological studies. Schoolchildren wore a personal NO2 sampler, kept a time-activity diary and completed a questionnaire. This information was used by MEEM to estimate individuals' exposures. These were then compared against concentrations measured by OPS, modelled outdoor concentrations at the children's home (HOME) and concentrations measured at the nearest urban monitoring station (NUM). The mean exposure predicted by MEEM (mean = 19.6 μg m-³) was slightly lower than the mean exposure measured by OPS (mean = 20.4 μg m-³). The normalised mean bias factor (0.01) and normalised mean absolute error factor (0.25) suggested good agreement. In contrast, the HOME (mean = 31.2 μg m-³) and NUM (mean = 28.6 μg m-³) methods overpredicted exposure and showed systematic errors. The results indicate that personal exposure can be modelled by MEEM with an acceptable level of agreement, while methods such as HOME and NUM show a poorer performance.

  6. Studying permethrin exposure in flight attendants using a physiologically based pharmacokinetic model.

    PubMed

    Wei, Binnian; Isukapalli, Sastry S; Weisel, Clifford P

    2013-07-01

    Assessment of potential health risks to flight attendants from exposure to pyrethroid insecticides, used for aircraft disinsection, is limited because of (a) lack of information on exposures to these insecticides, and (b) lack of tools for linking these exposures to biomarker data. We developed and evaluated a physiologically based pharmacokinetic (PBPK) model to assess the exposure of flight attendants to the pyrethroid insecticide permethrin attributable to aircraft disinsection. The permethrin PBPK model was developed by adapting previous models for pyrethroids, and was parameterized using currently available metabolic parameters for permethrin. The human permethrin model was first evaluated with data from published human studies. Then, it was used to estimate urinary metabolite concentrations of permethrin in flight attendants who worked in aircrafts, which underwent residual and pre-flight spray treatments. The human model was also applied to analyze the toxicokinetics following permethrin exposures attributable to other aircraft disinsection scenarios. Predicted levels of urinary 3-phenoxybenzoic acid (3-PBA), a metabolite of permethrin, following residual disinsection treatment were comparable to the measurements made for flight attendants. Simulations showed that the median contributions of the dermal, oral and inhalation routes to permethrin exposure in flight attendants were 83.5%, 16.1% and 0.4% under residual treatment scenario, respectively, and were 5.3%, 5.0% and 89.7% under pre-flight spray scenario, respectively. The PBPK model provides the capability to simulate the toxicokinetic profiles of permethrin, and can be used in the studies on human exposure to permethrin.

  7. Exposure assessment at extremely low frequencies: Issues, instrumentation, modeling, and data

    NASA Astrophysics Data System (ADS)

    Sussman, Stanley S.

    1995-01-01

    Epidemiologic studies suggesting a possible link between exposure to ELF magnetic fields and increased cancer risk have spurred interest in the assessment of field levels and exposures in residences, the workplace, and other environments. Characteristics such as high degrees of spatial and temporal variability and the presence of multiple frequencies can complicate assessment strategies. Instrumentation development has proceeded rapidly, and a number of measurement systems of varying sophistication are now commercially available. For situations where measurement is not feasible or practical, computer modeling is expanding the scope of exposure estimation. Health-oriented studies and measurement surveys are adding to a growing database of field and exposure levels.

  8. ECOMORPH: A modelling approach to the physiological effects of contaminant exposure

    SciTech Connect

    Nogueira, A.J.A.; Soares, A.M.V.M.; Baird, D.J.

    1995-12-31

    Daphnia magna is both an ubiquitous filter feeder in freshwater ecosystems and a standard organism in ecotoxicology. Physiological effects of toxicants under chronic exposure have been extensively documented for Daphnia in the literature. In ecotoxicology, the usual individual test endpoints are growth, reproduction and survival. These are not always the direct result of exposure to a contaminant although they can be a side-effect of feeding depression. Thus, food deprivation experiments were used to identify and model key physiological processes under contaminant exposure. Insight from these experiments was used to develop an individual physiological model. The model was fully validated for D. magna using several classes of toxicants (including metals and organics). The model describes Daphnia growth, moulting, and reproduction dynamically while incorporating direct, non-lethal effects of toxicants. This ECOMORPH model is currently being developed for other organisms using the same structural framework, and can be used to predict the physiological effects of contaminant exposure.

  9. Comparison of screening-level and Monte Carlo approaches for wildlife food web exposure modeling

    SciTech Connect

    Pastorok, R.; Butcher, M.; LaTier, A.; Ginn, T.

    1995-12-31

    The implications of using quantitative uncertainty analysis (e.g., Monte Carlo) and site-specific tissue residue data for wildlife exposure modeling were examined with data on trace elements at the Clark Fork River Superfund Site. Exposure of white-tailed deer, red fox, and American kestrel was evaluated using three approaches. First, a screening-level exposure model was based on conservative estimates of exposure parameters, including estimates of dietary residues derived from bioconcentration factors (BCFs) and soil chemistry. A second model without Monte Carlo was based on site-specific data for tissue residues of trace elements (As, Cd, Cu, Pb, Zn) in key dietary species and plausible assumptions for habitat spatial segmentation and other exposure parameters. Dietary species sampled included dominant grasses (tufted hairgrass and redtop), willows, alfalfa, barley, invertebrates (grasshoppers, spiders, and beetles), and deer mice. Third, the Monte Carlo analysis was based on the site-specific residue data and assumed or estimated distributions for exposure parameters. Substantial uncertainties are associated with several exposure parameters, especially BCFS, such that exposure and risk may be greatly overestimated in screening-level approaches. The results of the three approaches are compared with respect to realism, practicality, and data gaps. Collection of site-specific data on trace elements concentrations in plants and animals eaten by the target wildlife receptors is a cost-effective way to obtain realistic estimates of exposure. Implications of the results for exposure and risk estimates are discussed relative to use of wildlife exposure modeling and evaluation of remedial actions at Superfund sites.

  10. A Comparison of Two Strategies for Building an Exposure Prediction Model.

    PubMed

    Heiden, Marina; Mathiassen, Svend Erik; Garza, Jennifer; Liv, Per; Wahlström, Jens

    2016-01-01

    Cost-efficient assessments of job exposures in large populations may be obtained from models in which 'true' exposures assessed by expensive measurement methods are estimated from easily accessible and cheap predictors. Typically, the models are built on the basis of a validation study comprising 'true' exposure data as well as an extensive collection of candidate predictors from questionnaires or company data, which cannot all be included in the models due to restrictions in the degrees of freedom available for modeling. In these situations, predictors need to be selected using procedures that can identify the best possible subset of predictors among the candidates. The present study compares two strategies for selecting a set of predictor variables. One strategy relies on stepwise hypothesis testing of associations between predictors and exposure, while the other uses cluster analysis to reduce the number of predictors without relying on empirical information about the measured exposure. Both strategies were applied to the same dataset on biomechanical exposure and candidate predictors among computer users, and they were compared in terms of identified predictors of exposure as well as the resulting model fit using bootstrapped resamples of the original data. The identified predictors were, to a large part, different between the two strategies, and the initial model fit was better for the stepwise testing strategy than for the clustering approach. Internal validation of the models using bootstrap resampling with fixed predictors revealed an equally reduced model fit in resampled datasets for both strategies. However, when predictor selection was incorporated in the validation procedure for the stepwise testing strategy, the model fit was reduced to the extent that both strategies showed similar model fit. Thus, the two strategies would both be expected to perform poorly with respect to predicting biomechanical exposure in other samples of computer users.

  11. Matching next-to-leading order predictions to parton showers in supersymmetric QCD

    DOE PAGESBeta

    Degrande, Céline; Fuks, Benjamin; Hirschi, Valentin; Proudom, Josselin; Shao, Hua-Sheng

    2016-02-03

    We present a fully automated framework based on the FeynRules and MadGraph5_aMC@NLO programs that allows for accurate simulations of supersymmetric QCD processes at the LHC. Starting directly from a model Lagrangian that features squark and gluino interactions, event generation is achieved at the next-to-leading order in QCD, matching short-distance events to parton showers and including the subsequent decay of the produced supersymmetric particles. As an application, we study the impact of higher-order corrections in gluino pair-production in a simplified benchmark scenario inspired by current gluino LHC searches.

  12. Matching next-to-leading order predictions to parton showers in supersymmetric QCD

    NASA Astrophysics Data System (ADS)

    Degrande, Céline; Fuks, Benjamin; Hirschi, Valentin; Proudom, Josselin; Shao, Hua-Sheng

    2016-04-01

    We present a fully automated framework based on the FEYNRULES and MADGRAPH5_aMC@NLO programs that allows for accurate simulations of supersymmetric QCD processes at the LHC. Starting directly from a model Lagrangian that features squark and gluino interactions, event generation is achieved at the next-to-leading order in QCD, matching short-distance events to parton showers and including the subsequent decay of the produced supersymmetric particles. As an application, we study the impact of higher-order corrections in gluino pair-production in a simplified benchmark scenario inspired by current gluino LHC searches.

  13. Higgs characterisation via vector-boson fusion and associated production: NLO and parton-shower effects

    NASA Astrophysics Data System (ADS)

    Maltoni, Fabio; Mawatari, Kentarou; Zaro, Marco

    2014-01-01

    Vector-boson fusion and associated production at the LHC can provide key information on the strength and structure of the Higgs couplings to the Standard Model particles. Using an effective field theory approach, we study the effects of next-to-leading order (NLO) QCD corrections matched to a parton shower on selected observables for various spin-0 hypotheses. We find that inclusion of NLO corrections is needed to reduce the theoretical uncertainties on the total rates as well as to reliably predict the shapes of the distributions. Our results are obtained in a fully automatic way via FeynRules and MadGraph5_aMC@NLO.

  14. Analysis of the relation between exposure parameters and critical dimension by response surface model

    NASA Astrophysics Data System (ADS)

    Sohn, Dong-Soo; Sohn, Young-Soo; Bak, Heungin; Oh, Hye-Keun

    2001-08-01

    It is important to know the relationship between the soft bake conditions and the Dill exposure parameters in order to control the lithographic process well. It has been reported that exposure parameter A can be significantly affected by the soft bake conditions, while the exposure parameters B and C show no dependency on the soft bake conditions. The exposure parameters have been considered less important in 193 nm chemically amplified resist (CAR) simulation. Since the critical dimension variation depends on the exposure parameters, if we know the relationship between them it would be helpful in developing resist and resist process. In this paper the profiles of a 193nm CAR were simulated with the various Dill exposure parameters and the results were analyzed by response surface model. The response surface methodology (RSM) approach was used to analyze the influence of independent factors on a dependent response, and to optimize each process. A method of steepest ascent was utilized to produce first-order models, which were verified by lack of fit testing. As optimum operation points were approached, a second-order model was fitted and analyzed. The Dill exposure parameter C affects critical dimension greatly whereas A and B have much less effect. Among parameters other than exposure parameters, PEB time and PEB temperature are great factors to affect critical dimension. Even small change of them can make great critical dimension changes. Process optimization for the target response value as well as process latitude was possible through the use of the response surface.

  15. Application of thermoluminescence for detection of cascade shower 2: Detection of cosmic ray cascade shower at Mount Fuji

    NASA Technical Reports Server (NTRS)

    Akashi, M.; Kawaguchi, S.; Watanabe, Z.; Misaki, A.; Niwa, M.; Okamoto, Y.; Fujinaga, T.; Ichimura, M.; Shibata, T.; Dake, S.

    1985-01-01

    The results of a thermoluminescence (TL) chamber exposed at Mt. Fuji during Aug. '83 - Aug. '84 are reported. The TL signal induced by cosmic ray shower is detected and compared with the spot darkness of X-ray film exposed at the same time.

  16. Combining Regional- and Local-Scale Air Quality Models with Exposure Models for Use in Environmental Health Studies

    EPA Science Inventory

    Population-based human exposure models predict the distribution of personal exposures to pollutants of outdoor origin using a variety of inputs, including: air pollution concentrations; human activity patterns, such as the amount of time spent outdoors vs. indoors, commuting, wal...

  17. A model to assess personal exposure to ELF magnetic fields from common household sources

    SciTech Connect

    Delpizzo, V. )

    1990-01-01

    Emission data are inadequate to characterize the contribution of a source to the total personal extremely-low-frequency (ELF) magnetic field exposure. In this paper, a simple model is proposed that takes into consideration the position of the subject with respect to the source and the duration of exposure. The magnetic field is spatially averaged over the whole body of the exposed subject and integrated over time. Exposure is regarded as significant if it approaches or exceeds 400 microT-h/year. By use of this method, the ELF magnetic fields generated by several household sources were compared with the levels of residential external sources, to assess their relative significance. Some common domestic electrical appliances are found to be responsible for an exposure comparable to that from power lines. When the model is used to assess exposure to electric blankets, apparently conflicting findings may be reconciled.

  18. The rat exposure test: a model of mouse defensive behaviors.

    PubMed

    Yang, Mu; Augustsson, Hanna; Markham, Chris M; Hubbard, David T; Webster, Dylan; Wall, Phillip M; Blanchard, Robert J; Blanchard, D Caroline

    2004-05-01

    In order to facilitate behavioral, and potentially pharmacological, analyses of risk assessment behaviors in mice, a rat exposure test (RET) was devised and evaluated. This test provides a home chamber connected via a tunnel to a rat (predator) exposure area. Familiar substrate is provided to permit burying, and mouse subjects are habituated to the apparatus prior to exposure to an amphetamine-activated rat. In comparison to toy-rat-exposed controls, rat-exposed BALB/c mice showed significantly more risk assessment [stretch attend posture (SAP) and stretch approach], freezing, and avoidance (time in the home chamber), and less time in contact with the wire mesh screen between itself and the threat stimulus. When BALB/c, C57BL/6, CD-1, and Swiss-Webster mice were compared in this test, the two inbred strains (BALB/c and C57BL/6) tended to show more extreme values of particular defensive behaviors, compared to the two outbred strains (Swiss-Webster and CD-1). C57BL/6 mice showed more avoidance and higher levels of SAP, freezing, and burying than BALB/c and more than one or both outbred strains as well. BALB/c mice showed little defensive burying, both in comparison to toy-exposed controls (Experiment 1), and in comparison to the three other strains in Experiment 2. These findings are somewhat at variance with characterizations of anxiety in C57BL/6 and BALB/c mice, based on tests utilizing novel areas and noxious stimuli, suggesting strain differences in defensiveness to such stimuli, compared to antipredator defense levels. Nonetheless, with the exception of burying in BALB/c mice, all strains showed all defensive behaviors measured to the rat stimulus. In particular, SAP levels were substantial in all strains tested, suggesting the usefulness of this test in assessment of the role of risk assessment in defense.

  19. Linkage of exposure and effects using genomics, proteomics and metabolomics in small fish models (presentation)

    EPA Science Inventory

    This research project combines the use of whole organism endpoints, genomic, proteomic and metabolomic approaches, and computational modeling in a systems biology approach to 1) identify molecular indicators of exposure and biomarkers of effect to EDCs representing several modes/...

  20. USING CMAQ FOR EXPOSURE MODELING AND CHARACTERIZING THE SUB-GRID VARIABILITY FOR EXPOSURE ESTIMATES

    EPA Science Inventory

    Atmospheric processes and the associated transport and dispersion of atmospheric pollutants are known to be highly variable in time and space. Current air quality models that characterize atmospheric chemistry effects, e.g. the Community Multi-scale Air Quality (CMAQ), provide vo...